boiler auxillaries in a coal fired power plant

Analysis of BOILER AUXILIARIES

Fuel Preparation & Transportation Circuit

Fuel Oil Circuit DM Water Circuit

Cooling Water Circuit Air Circuit

Steam Circuit Condensate Circuit

Flue Gas Circuit Ash Evacuation circuit

Electrical circuit

Thermal Power Plant Layout COAL, AIR AND FLUE GAS CIRCUITS

BUNKER

FEEDER

In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder.

The thermal efficiency of boiler depends on the specific coal consumption and is usually expressed as MT of coal burnt per MU of energy produced. The micro processor based gravimetric feeder control system continuously weighs the weight of coal fed to pulveriser proportional to the changing demand. The rate of coal fed signal is used to maintain the excess air quantity at the optimum level to make the combustion process efficient. The secondary purpose of a gravimetric feeder is to give the total coal weight of coal fed during an interval of time.

Coal Feeder Introduction

Technical Details of Coal Feeder

Technical Details

Application Coal Feeder

Coal Feeder type Gravimetric Feeder

No /Boiler Six

Feeder Size 36” Feeder inlet

Capacity (T/Hr) 17 TPH (min.) 85 TPH (max.)

Center Distance 7’

Gear Ratio-main drive 128:1

Gear Ratio-COC drive 1039.9:1

Working pressure 500 mmWC

Head Pulley assembly

Main drive motor with gear box

Clean Out Conveyor System

Belt Take-up Pulley Assembly

Weigh Span Roller Assembly

Weigh Sensing System Assembly

Inlet Span Roller Assembly

Tension Roll Assembly

Coal On Belt Alarm Assembly

Belt & Belt scraper

Main Constituents

Constructional feature of Coal Feeder


Contd….

* Belt & Drive System The feeder belt is supported by a machined drive pulley near the outlet, a slotted take-up pulley and six belt support rollers at the inlet end, a weighted idler in the middle of the feeder. A counterweighted scraper with replaceable rubber blade continuously cleans the carrying surface of the belt after the coal is delivered to the outlet.

* Clean Out Conveyor (COC) System Two strands of malleable iron drag chain with alternately- spaced wing links are used to automatically clean coal from the bottom pan of the feeder. The cleanout conveyor is driven by drive. It is recommended that the cleanout conveyor be operated continuously. Shear pin in the gearbox limits the output torque to prevent mechanical overload and damage.

Main Components

Constructional feature of Coal Feeder Belt & Drive System


* Feed Rate Sensing Procedure

The feeder weighing signal is generated by two load cells which support a

weighing roller. Located on each side of the weighing roller are two weigh span

rollers, which accurately define a given length of belt on which the coal is weighed.

Each load cell is scaled into a signal, which represents grains of coal per

centimeters of belt. This weight data contributes to the feed rate formula from

which the feeder is operated

Weight (gm/cm) X Belt speed (cm./sec.)= Feed rate (gm/sec.)

Main Components

Constructional feature of Coal Feeder Feed Rate Sensing Procedure

Bowl Mill is employed to pulverize the pre-crushed raw coal to required fineness before it is admitted in to the boiler furnace for combustion. Crushed raw coal at a controlled rate is feed into the revolving bowl of the Bowl Mill. Centrifugal force feeds the coal uniformly over the replaceable grinding ring where independently spun rolls exert the required grinding pressure.

Coal Mills Introduction

Technical Details of Coal Mill

Contd….

Technical Details

Application Coal Mill

Mill type XRP 903

No /Boiler Six

Type of Drive Planetary Gear Box

Capacity (T/Hr) 50.8

Max Coal Feed size (mm) 50

Mill Speed (rpm) 47.5

Technical Details of Coal Mill

Technical Details

Motor Make BHEL Bhopal

Motor Speed (rpm) 981

Motor Rating (KW) 450

Gear Box Lubrication 150 LPM FOLS (Servo Mesh SP 320)

Journal assembly Lubrication Servo Mesh SP 680

Journal Upper Bearing HH249949 Assly 90026 (Timken)

Journal Lower Bearing EE350750 / 351687 (Timken)

Mill – Motor Coupling Flexible (Bibby & Gear combination)

Technical Details of Bowl Mill- XRP 903

Coal Mill Designation

XRP 903

X - 3 Phase 50Hz Supply R - Raymond (Inventor of the mill) P - Pressurized 90 - Nominal Dia of the Bowl (in Inch) 3 - No of Grinding Rolls

Planetary Gear Box.

Bowl & Bowl hub assembly.

Scraper & guard assembly.

Journal assembly.

Separator top assembly.

Classifier Assembly.

Mill Discharge Valve (MDV)

Center feed pipe

Lube oil skirt.

Seal air header & pipings.

Main Constituents

Constructional feature of Coal Mill

Planetary Gear Box


Mill Side and Liner Body


Mill Separator Body


Exploded Bowl Hub Assembly


Bowl Hub Assembly


Classifier Assembly


Journal Opening Cover


Journal Shaft Assembly


Journal Assembly


Arrangement of MDV


Mill Discharge Valve


Hot Air

Gate

Cold Air

Inspection Door Coal

Mill

Hot Air Duct

Scraper

Housing

Hot Air Damper

Gear

Housing

Grinding

Chamber

Discharge

System

Classifying

System

Coal from bunker

Grinding

Rolls

Coal discharge

Air flow

Classification of

desired fineness

Coal

Pulverized Coal

Dropping of

undesired coarse

Coal

Boben Anto C

PRIMARY AIR

(Air for drying & Transportation of Pulverized Coal)

The air used to convey and dry the

pulverized coal is referred to as primary air.

Two primary air fans supply the air to the

pulveriser to assure proper drying in the

pulverisers and to transport the pulverized

coal from pulveriser to coal burners. The

temperature of the primary air to mills will

be controlled depending upon the moisture

content in coal.

Contd….

The tempering air (cold air) tapped before

the air heater is used to control the air

temperature at mill inlet. The primary air

fan is modulated to maintain a pre

determined pressure in the pulveriser hot

air header pressure. The mill air flow is

maintained by adjusting the hot air

regulating damper while the mill outlet

temperature is maintained by adjusting the

cold air regulating damper.

PRIMARY AIR

(Air for drying & Transportation of Pulverized Coal)

Design Features - Variable pitch profiled blades Hydraulic servo control Single & two stages Bearings Antifriction tailor-made bearing housings

Main constituents

Suction chamber

Impeller housing

OGV & Diffuser

Impeller (blade bearing assly)

Blades (Al. alloy / cast iron)

Shaft (solid) with bearing assly

Servo-motor

(PA Fan) Axial Reaction Fans

Technical Details of PA Fan –one eg:

Contd….

Technical Details

Application Primary Air Fan

Fan type PAF 17/11.8-2 (TLT Design)

No /Boiler Two

Medium Atmospheric Air

Capacity (m3/s) 101

Total head (mmWC) 1370

Fan Speed (rpm) 1490

Technical Details of PA Fan

Technical Details



Motor Volts (volt) 6600

Fan Lubrication 15 LPM FOLS (SP 68)

Fan Regulation Blade Pitch Control

Bearing 7034 B.MP.UA (03 Nos.)

Bearing NU 230E.M1.C3 (02Nos.)

Servo Motor 336-50

Fan – Motor Coupling Regiflex, Spacer Type

Technical Details of PA Fan

PA Fan Designation

PAF 17 / 11.8 - 2 PAF - Primary Air Fan 17 - Impeller tip diameter in Decimeter 11.8 - Hub diameter in Decimeter 2 - Double stage

Constructional feature of PA Fan

Contd….


Contd….

The P A Fan consists of the following Components :-

Stator consisting of Suction Box, Fan housing, Outlet Guide Vane

housing with guide vanes and Diffuser.

Rotor consisting of shaft, two impeller with 24 blades (PA Fan) the

Blade Bearing Assembly, the Hydraulic Blade Adjustment Device

(Servo Motor) and Shaft with Bearing Assembly (Anti- friction

bearings)


Contd….


Contd….

Suction Box and Fan Housing, Outlet Guide Vane housing and

diffuser are flexibly connected via expansion joints.

Fan and Outlet guide vane housings are horizontally split, in order to

facilitate access of the rotor for dismantling and assembly.

Those parts of the Hydraulic impeller blade adjustment system unit

which are arranged in the guide vane and diffuser cores are

accessible through manual door.

STATOR :


Contd….

STATOR :

Fan Housing

Suction Box Fan Housing

Outlet Guide Vane housing

Diffuser


Contd….

The rotor assembly consists of a main bearing assembly and two impeller with 24 blades each, the blade bearing assemblies, the hydraulic impeller blade adjustment system.

* Shaft With Bearing Assembly

The main bearing, a compact unit, is centered and screwed in the lower half of the fan housing.

The Shaft with Bearing Assembly is accommodated with 02 Cylindrical Roller bearing (NU 230 E M1 C3) and 03 Angular Contact ball bearings (7034 B MP UA).

ROTOR ASSEMBLY (PA Fan):


Contd….

Shaft with Bearing Assembly


Contd….

* Impeller Assembly

The impeller consist of a hub, a supporting disk, a solid load ring for taking

up the centrifugal forces and a guide ring. Hub and fan shaft are connected

by interference fit and secured with a key.

* Hydraulic Blade Adjustment Device

The blades will be adjusted and kept in position during operation by the

hydraulic impeller blade adjustment system.


Contd….

Impeller Assembly


Contd….

Hydraulic Blade Adjustment Device (Servo Motor)


Contd….

* Adjusting Shaft (Setting Shaft)

The mechanical connection between the hydraulic impeller blade

adjustment device and the respective components outside of the fan

housing is attained via an indicator shaft and a setting shaft. An external

actuator (Power Cylinder) effects the hydraulic impeller blade adjustment

device via the setting shaft.


Contd….

Power Cylinder & Setting Shaft


Contd….

FAN ACCESSORIES

* Regiflex Coupling

The fan shaft is connected to the motor shaft by means of Regiflex coupling

while the distance between the shaft ends is bridged by an intermediate

shaft which is a part of the coupling assembly.

* Drive Motor

Constant speed synchronous induction motors drive these fans.


Contd….

OIL CIRCULATION UNIT

The oil unit (having capacity of 35 Bar and 15 LPM) consists of an oil tank,

two pumps (one standby), filters, oil coolers and other necessary fittings

and instruments. A pressure relief valve maintains the pressure in the

system for fan bearing lubrication (5 Bar) and Servo motor control (28 Bar).

The lubricating oil is fed through a pressure compensated flow-regulating

valve.

Constructional feature of PA Fan Oil Circulation Unit:

Contd….

The total air flow through the unit is

handled by two numbers of axial reaction

forced draft fans and two numbers of axial

reaction primary air fans. The flue gas

produced in the furnace from combustion

of fuel is evacuated by two numbers of

radial double suction induced draft fans.

Correct amount of air is the most essential ingredient for Combustion. More air or less air both makes the combustion process inefficient.

COMBUSTION AIR (Secondary Air)

Design Features - Variable pitch profiled blades Hydraulic servo control Single & two stages Bearings Antifriction tailor-made bearing housings

Main constituents

Suction chamber

Impeller housing

OGV & Diffuser

Impeller (blade bearing assly)

Blades (Al. alloy / cast iron)

Shaft (solid) with bearing assly

Servo-motor

(FD Fan) Axial Reaction Fans -one eg

Technical Details of FD & PA Fan

Contd….

Technical Details

Application Forced Draft Fan

Fan type FAF 17/9.5-1 (TLT Design)

No /Boiler Two

Medium Atmospheric Air

Capacity (m3/s) 107


Fan Speed (rpm) 1490

Technical Details of FD & PA Fan

Technical Details





Fan Regulation Blade Pitch Control

Bearing 7226 B.MP.UA (02 Nos.)

Bearing NU 226E.M1.C3 (01 No.)

Servo Motor 200-50

Fan – Motor Coupling Regiflex, Spacer Type

Technical Details of FD Fan

FD Fan Designation

FAF 17 / 9.5 - 1 FAF - Forced Draft Fan 17 - Impeller tip diameter in Decimeter 9.5 - Hub diameter in Decimeter 1 - Single stage

Constructional feature of FD Fan

Contd….


Contd….

The F D Fan consists of the following Components :-

Stator consisting of Suction Box, Fan housing, Outlet Guide Vane

housing with guide vanes and Diffuser.

Rotor consisting of shaft, one impeller with 18 blades (FD Fan) the

Blade Bearing Assembly, the Hydraulic Blade Adjustment Device

(Servo Motor) and Shaft with Bearing Assembly (Anti- friction

bearings)


Contd….


Contd….

Suction Box and Fan Housing, Outlet Guide Vane housing and

diffuser are flexibly connected via expansion joints.

Fan and Outlet guide vane housings are horizontally split, in order to

facilitate access of the rotor for dismantling and assembly.

Those parts of the Hydraulic impeller blade adjustment system unit

which are arranged in the guide vane and diffuser cores are

accessible through manual door.

STATOR :


Contd….

STATOR :

Fan Housing Suction Box Fan Housing

Outlet Guide Vane housing

Diffuser


Contd….

The Rotor Assembly consists of a Shaft with bearing assembly and one impeller with 18 blades, the blade bearing assemblies, the hydraulic impeller blade adjustment device.

* Shaft with Bearing Assembly (FD Fan)

The shaft with bearing assembly, a compact unit, is centered and screwed in the lower half of the fan housing.

The shaft with bearing assembly is accommodated with 01 Cylindrical Roller bearing and 02 Angular Contact ball bearings.

ROTOR ASSEMBLY (FD Fan):


Contd….

Shaft with Bearing Assembly


Contd….

* Impeller Assembly

The impeller consist of a hub, a supporting disk, a solid load ring for taking

up the centrifugal forces and a guide ring. Hub and fan shaft are connected

by interference fit and secured with a key.

* Hydraulic Blade Adjustment Device

The blades will be adjusted and kept in position during operation by the

hydraulic impeller blade adjustment system.


Contd….

Impeller Assembly


Contd….

Hydraulic Blade Adjustment Device (Servo Motor)

Rotor Assembly

Blade Bearing Assembly

Mounting of the Adjusting Lever

Completely mounted Blade Shaft

Assembly of the Adjusting Lever

Adjusting Lever with Thrust Device

Rotor adjustment in final positions

Blades

opened

Blades

closed

Hydraulic Impeller Blade Adjustment System

Legend

1. Blade position 6. Adjusting lever

2. Feedback rod 7. Pressure oil

3. Control head 8. Return oil

4. Adjusting cylinder 9. Leackage oil

5. Piston 10. Local indication

11. Actuator


Contd….

* Adjusting Shaft (Setting Shaft)

The mechanical connection between the hydraulic impeller blade

adjustment device and the respective components outside of the fan

housing is attained via an indicator shaft and a setting shaft. An external

actuator (Power Cylinder) effects the hydraulic impeller blade adjustment

device via the setting shaft.


Contd….

Power Cylinder & Setting Shaft


Contd….

FAN ACCESSORIES

* Regiflex Coupling

The fan shaft is connected to the motor shaft by means of Regiflex coupling

while the distance between the shaft ends is bridged by an intermediate

shaft which is a part of the coupling assembly.

* Drive Motor

Constant speed synchronous induction motors drive these fans.


Contd….

Intermediate shaft & Coupling:


Contd….

OIL CIRCULATION UNIT

The oil unit (having capacity of 35 Bar and 15 LPM) consists of an oil tank,

two pumps (one standby), filters, oil coolers and other necessary fittings

and instruments. A pressure relief valve maintains the pressure in the

system for fan bearing lubrication (5 Bar) and Servo motor control (28 Bar).

The lubricating oil is fed through a pressure compensated flow-regulating

valve.

Constructional feature of FD Fan Oil Circulation Unit:

Contd….

The flue gas produced in the furnace as a result of combustion, travels upward in the furnace, across the horizontal pass and downward through the second pass of the boiler to the air preheaters. In the air heaters, the residual heat of the flue gas is utilized to preheat the secondary and primary air. The dust laden flue gas then passes through the ESP for dust removal. Induced draft fans (Radial 2 Nos.) are provided to evacuate the flue gas from furnace to chimney. The FD fans and ID fans are capable of maintaining balanced draft conditions in the furnace over the entire load range of the boiler.

Air Pre Heater

An air heater is an important Boiler auxiliary, which primarily preheats the combustion air for rapid and efficient combustion in the furnace. The air heater recovers the waste heat from the outgoing flue gas of a Boiler and transfers the same to the combustion air.

Types of Air Hater: • Recuperative Type Air Heater • Tubular Air Heater • Plate Type Air Heater • Regenerative Air Heater • Ljungstrom Air Heater

• Bi-Sector • Tri-Sector

Constructional Feature of Air Preheater

Here a matrix is rotated at 2 to 3 rpm and alternatively passes through the gas and air passes .the heating elements pick up the heat from the flue gas and same elements gives the heat to the air when they move through the air pass. The air heater can be bisector or tri-sector. In tri-sector air heater, there will be provision for heating the primary and secondary air streams separately. This facilitates to handle cold air to the primary air fan.

Ljungstrom Air Heater

Air Preheater - Designation Make : BHEL Heater Size : 27.5 VITM 2000 Type : Rotary Regenerative tri-sector Total Nos / Boiler : 02 Total Heating Surface : 20613 m2 (each)

Gear Box Reduction Ratio : 110:01

Technical Details of Air Preheater

27.5 - Size of Air Heater VI - Vertical Inverted TM - Tri-sector, Modular Rotor 2000 - Element Depth in mm

Sector Arrangements

Constructional feature of Air Preheater

Contd….

Constructional Feature of Air Preheater

Rotor

Bearing

Housing

Connecting plates

Sealing arrangements

Drive units

Cleaning devices

Safety devices


Contd….

* Rotor

This is the hearts of the equipment which contains heating elements. The rotor have a rotor post at the centre and a shell which is connected to the rotor post by number of radial or diaphragm plates. These plates divide into number of sector and these sectors are further divided into compartments by division plates. The heating element basket are packed into these compartment . A pin rack is located the outside of the rotor to allow into be rotated by the drive mechanism.

* Rotor Post

This is a cylindrical shell with two end plated welded to it. At both ends trunnion will be connected to serve the purpose of the shaft and to accommodate the bearing on them. The end plates otherwise called headers will supports the modules that are to be assembled to them .the top header will have numbers of holes on its peripheral edge to assembled modules through the horizontal locating pins.

MAIN COMPONENTS

Rotor



Contd….

* Modules

Modules are nothing but cylindrical segments made out of two diaphragm plates and one shell plate (division plate). The diaphragm plates will be stayed with the cross plates to maintain their shapes. Inside these modules heat transfer profiles of sufficient area are packed, the outer shell will be mounted with pin racks for the engagements of drive units. At the extreme edges of these segments lug plates are provided to get the modules assembled to the rotor post to form a rotor.

* Bearings

Both the extended ends of the rotor post are mounted with bearing assembly. The bearings are of spherical roller types to take care of even slightest axial shift if takes place. The bearing at the cold end is called as support bearing and at the hot end is guide bearing. These bearing are housed inside the fabricated bearing housing with the oil sump inside.

MAIN COMPONENTS


Contd….

* Bearings

To dissipate then and there the heat generated in the bearing assembly lubricating oil circulation units with the necessary heat exchanger, oil filters and oil pumps are provided separately for each bearing.

* Heating Elements

The heating elements packed in reversible containers called baskets, and are placed in the rotor in three tiers, Hot, Intermediate and Cold. The heating elements in hot end and intermediate layer are having a profile called double undulated (DU). They made of carbon steel. The cold end heating elements are made of corten steel, which has resistance to corrosion. The undulations in the heating elements cause turbulence to the gas and air for efficient heat transfer. The notches are for maintaining the spacing between the elements and minimizing the pressure drop across the air heater.

MAIN COMPONENTS

Heating Elements



Contd….

* Connecting Plates

The connecting plates at the hot and cold ends connect the air heater to the gas and air ducts. They mainly consists of centre section to house the bearing and sector plates for providing sealing between the air and gas stream .further these form the bifurcation plates of the main pedestal.

* Sealing Arrangements

It is an implied requirement that the rotating parts should have some working clearance between their static parts to avoid any interference between them. Here, in air pre heaters, rotors are constructed to have higher clearances to take care of their thermal expansion and these gaps are closed with the flexible seal leaves . These seals are classified the following three major types. 1) Radial seals 2) Axial seals 3) Bypass seals The main purpose of these seals is to reduce the leakage of air into gas stream in radial, axial and circumferential directions respectively.

MAIN COMPONENTS

Gas & Air Leakages paths


Sealing Arrangements



Contd….

* Cleaning Device

The heat transfer matrix should be kept in a clean state to avoid the increase in fouling potentials and aerodynamic resistance. Also any un-burnt fuel deposits on these matrix may lead to a fire. So an on load cleaning facility by steam soot blowing is provided in the air pre heater to clean the heat transfer matrix during the operation itself. Also an off load cleaning can be effected with the water –washing nozzle through which high pressure water can be injected.

* Drive Units

The drive mechanism consists of an electric motor connected to a gear reduction unit through a pinion. The pinion meshes with a pin rack on the rotor, which allows the rotor to rotate at a slow speed. Air motor /DC motor is also provided to the drive arrangement, which will drive the rotor in emergencies like electric motor failure. Hand cranking in provided for uniform cooling after tripping in case air motor/DC motor also fail.

MAIN COMPONENTS

Constructional feature of Air Preheater AIR PREHEATER (schematic)

RADIAL SEAL

AXIAL

SEAL

BYPASS SEAL

COLD END

HOT END

HOT INTERMEDIATE

It is a device to precipitate suspended dust particles from the flue gas by ionizing the particles in an electric field and collecting them subsequently on oppositely charged electric plates. The dust laden flue gas enters the ESP through the perforated gas distributor to the parallel arrays of discharge electrodes spaced alternately with collecting electrodes.

Electro Static Precipitator (ESP) Introduction

Technical Details of ESP

Contd….

Technical Details

Application Electro Static Precipitator

Type of ESP FAA-8X45M-2X116150-2

No / Unit Two

No of Gas Path / ESP Two

No of Field in each Path Eight

No of Collecting Electrode / Field 59(row)x6(nos)=354

No of Collecting Electrode / ESP 5664

Technical Details of ESP: eg

Contd….

Technical Details

Total Height of Collecting Electrode 15 Meter

Emitting Electrode Spiral wire (Ø 2.7 mm) with Hook

No of Emitting Electrode / Field 58

Total No of Emitting Electrode / ESP 50112

Collecting Rapping Mechanism Geared Motor at Bottom

Emitting Rapping Mechanism Geared Motor at Top

HV Rectifier Rating 95 KV DC (PEAK), 1200mA DC (MEAN)

Technical Details of ESP

Technical Details

No of Ash Hoppers / ESP 32

Ash Holding Capacity of Hopper

No of Heater / ESP 384

Max. Hopper Temperature 120 0 C

Frequency of Rapping 15 Rap / Hr. - 01 Rap / Hr.

Efficiency of ESP 99.94%

Outlet Dust Concentration <50 mg/Nm³

Discharge electrodes

Collection electrodes

High voltage electrical systems

Rappers

Hoppers

Shell

Main Constituents

Constructional feature of ESP


Contd….

* Discharge Electrodes The discharge electrodes are thin, round wires varying from 0.25 cm in diameter. The discharge electrodes are hung vertically, supported at the top by a frame and held tight at bottom. The wires are usually made from high-carbon steel, stainless steel, copper, titanium alloy, and aluminum.

* Collection Electrodes Most precipitators use plate collection electrodes because these units treat large gas volumes and are designed to achieve high collection efficiency. The plates are made of carbon steel, stainless steel or an alloy steel. Plates are usually 15.2 m high & 0.75 m in width.

Main Components

Constructional feature of ESP Discharge & Collecting Electrodes


Contd….

* High-voltage equipment High-voltage equipment determines and controls the strength of the electric field generated between the discharge and collection electrodes. Power supply sets consisting of three components:

a step-up transformer, a high-voltage rectifier, and Control metering and protection circuitry (automatic circuitry).

These power sets are also commonly called transformer-rectifier (T-R) sets . In a T-R set, the transformer steps up the voltage from 400 volts to approximately 50,000 volts. This high voltage ionizes gas molecules that charge particles in the flue gas. The rectifier converts alternating current to direct current required for electrical precipitation. Most modern precipitators use solid-state silicon rectifiers and oil-filled, high-voltage transformers

Main Components

Constructional feature of ESP High Voltage Equipments


Contd….

* Rappers

Dust deposits are generally dislodged by mechanical impulses, or vibrations,

imparted to the electrodes. Collection electrodes are rapped by hammer.

* Hammer

Rapper system uses hammers mounted on a rotating shaft. As the shaft rotates, the

hammers drop (by gravity) and strike anvils that are attached to the collection

plates. The frequency of rapping can be changed by adjusting the speed of the

rotating shafts.

Main Components

Constructional feature of ESP Rappers & Hammers


Contd….

* Shell

The shell structure encloses the electrodes and supports the precipitator

components in a rigid frame to maintain proper electrode alignment and

configuration. The outer sheet or casing wall is usually made of low-carbon or

mild-grade steel that is 0.5 to 0.6 cm thick. Collection plates and discharge

electrodes are normally attached to the frame at the top so that the elements hang

vertically due to gravity allowing the elements to expand or contract with

temperature changes without binding or distorting.

Main Components

Constructional feature of ESP ESP Shell


Contd….

* Hopper

When the electrodes are rapped, the dust falls into hoppers and is stored

temporarily before it is convey through pipeline or reused in the process. An

inspection door is provide on each hopper. Hoppers are usually designed with a 50

to 70° (60° is common) slope to allow dust to flow freely. Thermostatically

controlled heating element are arranged at the bottom portion of the hopper to

ensure free flow of ash.

Main Components

Constructional feature of ESP ESP Hopper

Design features - Single & Double suction (NDV & NDZV) Controls - Inlet Damper, Inlet Guide Vane Speed control (Hyd. Coupling / VFD) Bearings - Antifriction / Sleeve

Main constituents

Suction chamber

Spiral casing (wear liners)

Impeller (wear liners)

Shaft (hollow / solid)

Bearing pedestal

Bearings & Housing

(ID Fan) Radial Fans: one eg

ID Fan - Designation

NDZV 33 SIDOR NDZV - Radial, Double suction, Simply supported design, Backward curved bladed Fan 33 - Impeller tip diameter in Decimeter SIDOR - Impeller type

Technical Details of ID Fan


Technical Details

Application Induced Draft Fan

Fan type NDZV 33 S

No /Boiler Two

Medium Flue Gas

Capacity (m3/s) 265


Fan Speed (rpm) 710

Contd….


Technical Details





Fan Regulation Inlet Guide Vane & Hydraulic Coupling

DE & NDE Bearing 8” RTL Water Cooled (Dodge / Marmec Make)

IGV Control By Power Cylinder

Hydraulic Coupling SVNL 1210

Connecting Coupling Metaflex coupling

Double Inlet

Support Bearings

Impeller

Hollow Shaft

Single Outlet

Constructional Feature of ID Fan

Constructional feature of ID Fan

Spiral Casing consisting of suction chamber Fan housing, Inlet Guide

Vane.

Rotor Assembly consisting of Shaft, Impeller blades with wear liner

plates and Conical cover plate.

Bearings Sleeve bearing of Dodge make (8” RTL Type) is used to

support rotor assembly at two ends.

MAIN COMPONENTS


IGV

Spiral Casing

Liners

SPIRAL CASING


Impeller

Shaft

Conical Cover

Plate

ROTOR ASSEMBLY


Journal Portion

Impeller Mounting

Flange

SHAFT


Impeller wear

liner

IMPELLER ASSEMBLY

Conical Cover


Lub oil Inlet

Cooling Water Inlet

Oil Level Indicator

SLEEVE BEARING

Any further analysis contact

[email protected]

boiler auxillaries in a coal fired power plant

Engineering