04102023CHAPTER 12 FURNACE amp KILNS 1

FURNACE amp KILNS

04102023CHAPTER 12 FURNACE amp KILNS 2

FURNACE

bull A furnace is a device used for heating The name derives from Latin fornax oven

bull It is essentially a thermal enclosure and is employed to process raw materials at high temperatures both in solid state and liquid state

04102023CHAPTER 12 FURNACE amp KILNS 3

The principle objectives are

a) To utilize heat efficiently so that losses are minimum and

b) To handle the different phases (solid liquid or gaseous) moving at different velocities for different times and temperatures such that erosion and corrosion of the refractory are minimum

04102023CHAPTER 12 FURNACE amp KILNS 4

bull Furnaces are usually made of either insulating firebrick or firebrick covered with refractory material The charge or inlet material is introduced by chutes conveyors or pipes The furnace can run in batch mode or in continuous mode The charge moves through the furnace on skids or rolls or by gravity rotation slope or mechanical pushers such as screws

04102023CHAPTER 12 FURNACE amp KILNS 5

bull Furnaces can be direct fired over fired under fired or side fired In direct fired furnaces the heat is produced on the inside of the furnace chamber In over under and side fired furnaces heat is produced in a chamber in the respective area and flows throughout the furnace

04102023CHAPTER 12 FURNACE amp KILNS 6

TYPES CLASSIFICATION CLASSES

1 Combustion Furnace

2 Electric Furnace

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 2

FURNACE

bull A furnace is a device used for heating The name derives from Latin fornax oven

bull It is essentially a thermal enclosure and is employed to process raw materials at high temperatures both in solid state and liquid state

04102023CHAPTER 12 FURNACE amp KILNS 3

The principle objectives are

a) To utilize heat efficiently so that losses are minimum and

b) To handle the different phases (solid liquid or gaseous) moving at different velocities for different times and temperatures such that erosion and corrosion of the refractory are minimum

04102023CHAPTER 12 FURNACE amp KILNS 4

bull Furnaces are usually made of either insulating firebrick or firebrick covered with refractory material The charge or inlet material is introduced by chutes conveyors or pipes The furnace can run in batch mode or in continuous mode The charge moves through the furnace on skids or rolls or by gravity rotation slope or mechanical pushers such as screws

04102023CHAPTER 12 FURNACE amp KILNS 5

bull Furnaces can be direct fired over fired under fired or side fired In direct fired furnaces the heat is produced on the inside of the furnace chamber In over under and side fired furnaces heat is produced in a chamber in the respective area and flows throughout the furnace

04102023CHAPTER 12 FURNACE amp KILNS 6

TYPES CLASSIFICATION CLASSES

1 Combustion Furnace

2 Electric Furnace

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 3

The principle objectives are

a) To utilize heat efficiently so that losses are minimum and

b) To handle the different phases (solid liquid or gaseous) moving at different velocities for different times and temperatures such that erosion and corrosion of the refractory are minimum

04102023CHAPTER 12 FURNACE amp KILNS 4

bull Furnaces are usually made of either insulating firebrick or firebrick covered with refractory material The charge or inlet material is introduced by chutes conveyors or pipes The furnace can run in batch mode or in continuous mode The charge moves through the furnace on skids or rolls or by gravity rotation slope or mechanical pushers such as screws

04102023CHAPTER 12 FURNACE amp KILNS 5

bull Furnaces can be direct fired over fired under fired or side fired In direct fired furnaces the heat is produced on the inside of the furnace chamber In over under and side fired furnaces heat is produced in a chamber in the respective area and flows throughout the furnace

04102023CHAPTER 12 FURNACE amp KILNS 6

TYPES CLASSIFICATION CLASSES

1 Combustion Furnace

2 Electric Furnace

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 4

bull Furnaces are usually made of either insulating firebrick or firebrick covered with refractory material The charge or inlet material is introduced by chutes conveyors or pipes The furnace can run in batch mode or in continuous mode The charge moves through the furnace on skids or rolls or by gravity rotation slope or mechanical pushers such as screws

04102023CHAPTER 12 FURNACE amp KILNS 5

bull Furnaces can be direct fired over fired under fired or side fired In direct fired furnaces the heat is produced on the inside of the furnace chamber In over under and side fired furnaces heat is produced in a chamber in the respective area and flows throughout the furnace

04102023CHAPTER 12 FURNACE amp KILNS 6

TYPES CLASSIFICATION CLASSES

1 Combustion Furnace

2 Electric Furnace

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 5

bull Furnaces can be direct fired over fired under fired or side fired In direct fired furnaces the heat is produced on the inside of the furnace chamber In over under and side fired furnaces heat is produced in a chamber in the respective area and flows throughout the furnace

04102023CHAPTER 12 FURNACE amp KILNS 6

TYPES CLASSIFICATION CLASSES

1 Combustion Furnace

2 Electric Furnace

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 6

TYPES CLASSIFICATION CLASSES

1 Combustion Furnace

2 Electric Furnace

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 7

Table 1 Classification of Combustion Furnaces

Classification Method Types and Examples

Type of fuel used

Combustion Type1048707 Oil-fired1048707 Gas-fired1048707 Coal-fired

Mode of charging materials

Intermittent BatchPeriodical1048707 Forging1048707 Re-rolling (batchpusher)1048707 PotContinuous1048707 Pusher1048707 Walking beam1048707 Walking hearth1048707 Continuous recirculating bogie furnaces1048707 Rotary hearth furnaces

Mode of heat transfer

Radiation (open fire place)Convection (heated through medium)

Mode of waste heat recovery

RecuperativeRegenerative

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 8

TYPICAL FURNACE SYSTEM i Forging Furnaces

The forging furnace is used for preheating billets and ingots to attain a lsquoforgersquo temperature The furnace temperature is maintained at around 1200 to 1250degC

ii Rerolling Mill Furnace

a Batch type A box type furnace is employed for batch type rerolling mill The furnace basically used for heating up scrap small ingots and billets weighing 2 to 20 kg for rerolling

b Continuous Pusher Type The process flow and operating cycles of a continuous pusher type is the same as that of the batch furnace

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 9

iii Continuous Steel Reheating Furnaces

The main function of a reheating furnace is to raise the temperature of a piece of steel typically to between 900degC and 1250degC until it is plastic enough to be pressed or rolled to the desired section size or shape

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 10

ELECTRIC FURNACE

bull A chamber heated by electric current is known as Electric Furnace Electric furnaces are cheaper than oil fired furnaces and gas fired furnaces

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 11

ELECTRIC FURNACE

bull Operating Principle

Steel scrap and a small amount of carbon and limestone are dropped into the electric furnace through the open roof The roof is then closed and the electrodes are lowered Power is turned on and within a period of about two hours the metal melts The current is then shut off the electrodes are raised the furnace is tilted and the molten metal is poured into a ladle which is a receptacle used for transferring and pouring molten metal

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 12

ELECTRIC FURNACE

Fig 1 Schematic illustration of types of Electric Furnaces (a) direct arc (b) indirect arc and (c) induction

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 13

COMPONENTS amp PARTS

Figure 2 Typical Furnace Components

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 14

APPLICATION AND USES

bull High temperatures soften melt and anneal the metals Heating can also cause the absorption of carbon Furnaces are used in various stages of heat treatment as shown in the table below for steel treatment

Treatmentheat-treatingannealinghardeningheatingreheating

Temperature Rangeup to 1200degF1200-1600degF1500-1600degFup to 2300degFup to 2300degF

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 15

APPLICATION AND USES

bull Furnaces are also used to melt glass coke coal distill zinc and many other processes Hearth furnaces can be used to remove hazardous waste They are also used in the microelectronics industry in semiconductor wafer production

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 16

KILNS

bull A kiln is a thermally insulated chamber a type of oven that produces temperatures sufficient to complete some process such as hardening drying or chemical changes

bull Kilns are furnaces used for ceramic or brick heating causing moisture and organic materials to evaporate Kilns are heated by horizontal space burners with gas liquid or solid fuel

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 17

TYPES CLASSIFICATION CLASSES

1 In using an intermittent kiln the ware to be fired is loaded into the kiln The kiln is closed and the internal temperature increased according to a schedule After the firing is completed both the kiln and the ware are cooled

Kilns in this type include

bull Clamp kiln

bull Skove kiln

bull Scotch kiln

bull Down-Draft kiln

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 18

2 A continuous kiln sometimes called a tunnel kiln is a long structure in which only the central portion is directly heated From the cool entrance ware is slowly transported through the kiln and its temperature is increased steadily as it approaches the central hottest part of the kiln From there its transportation continues and the temperature is reduced until it exits the kiln at near room temperature

Kilns in this type include

bull Hoffman kiln

bull Bullrsquos Trench kiln

bull Habla (Zig-Zag) kiln

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 19

Ceramic Kilns

bull Kilns are an essential part of the manufacture of all ceramics which require heat treatment often at high temperatures During this process chemical and physical reactions occur that permanently alter the unfired body In the case of pottery clay materials are shaped dried and then fired in a kiln

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 20

bull Wood Drying Kiln

A variety of wood drying kiln technologies exist today

1 Conventional wood dry kilns - are either package-type (side loader) or track-type (tram) construction

2 Dehumidification kilns - Heat comes primarily from an integral dehumidification unit that also removes humidity

3 Solar kilns - are conventional kilns typically built by hobbyists to keep initial investment costs low

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 21

bull Rotary Kilns

- is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process Materials produced using rotary kilns includebull Cement

bull Lime

bull Refractories

bull Metakaolin

bull Titanium dioxide

bull Alumina

bull Vermiculite

bull Iron ore pellet

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 22

OPERATING PRINCIPLE

bull The kiln is a cylindrical vessel inclined slightly to the horizontal which is rotated slowly about its axis The material to be processed is fed into the upper end of the cylinder As the kiln rotates material gradually moves down towards the lower end and may undergo a certain amount of stirring and mixing Hot gases pass along the kiln sometimes in the same direction as the process material (co-current) but usually in the opposite direction (counter-current) The hot gases may be generated in an external furnace or may be generated by a flame inside the kiln Such a flame is projected from a burner-pipe (or firing pipe) which acts like a large bunsen burner

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 23

COMPONENTS amp PARTS

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 24

APPLICATION amp USES

bull Tunnel kilns are used to vitrify clay bricks particulate solids and large solid objects They are also used to sinter capacitors soft ferrite composite materials and capacitors used in computers and cellular telephones also Rotary kilns are used to make cement and to calcine small waste stone and free-flowing granular solids Downdraft kilns are used to produce brick pipe tile and stoneware while updraft kilns are used for pottery burning

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25

04102023CHAPTER 12 FURNACE amp KILNS 25

Other uses of kiln include

bull To dry green lumber so it can be used immediately

bull Drying wood for use as firewood

bull Heating wood to the point of pyrolysis to produce charcoal

bull For annealing fusing and deforming glass or fusing metallic oxide paints to the surface of glass

bull For cremation (at high temperature)

bull Drying of tobacco leaves

bull Drying malted barley for brewing and other fermentations

bull Drying hops for brewing (known as a hop kiln or oast house)

bull Drying corn (grain) before grinding or storage sometimes called a corn kiln corn drying kiln

bull Smelting ore to extract metal

bull Heating limestone with clay in the manufacture of Portland cement

bull Heating limestone to make quicklime or calcium oxide

• FURNACE amp KILNS
• FURNACE
• Slide 3
• Slide 4
• Slide 5
• TYPES CLASSIFICATION CLASSES
• Slide 7
• Typical Furnace System
• Slide 9
• Electric Furnace
• Electric Furnace (2)
• Electric Furnace (3)
• COMPONENTS amp PARTS
• APPLICATION AND USES
• APPLICATION AND USES (2)
• KILNS
• TYPES CLASSIFICATION CLASSES (2)
• Slide 18
• Slide 19
• Slide 20
• Slide 21
• Operating Principle
• COMPONENTS amp PARTS (2)
• APPLICATION amp USES
• Slide 25