HEAT EXCHANGER USED IN BIOPROCESS INDUSTRY

SHALINI KASUHIKB.Tech (BT)4th Year

HEAT EXCHANGER

They are piece of equipment for efficient heat transfer.

Media may be separated by a solid wall or they may be in direct contact.

They may be used in powerplant

petroleum refineries sewage treatment air conditioning……etc example of Heat exchanger is found in an Internal

combustion engine.

TYPES OF HEAT EXCHANGERS

•Shell and tube exchangers.•Double pipe exchanger.•Plate heat exchangers.•Plate-fin exchangers.•Spiral heat exchangers.•Air cooled: cooling and condenser.•Agitated vessels.•Fired and heaters.

SHELL AND TUBE HEAT EXCHANGER

•Common type of heat exchanger in oil refineries and other large chemical processes.

• It consists of shell(a large pressure vessel) and a set of tubes inside the shell known as tube bundle.

•One fluid runs through the tube and another fluid flows over the tube to transfer the heat between the two fluids.

FEATURES :configuration gives a large surface area in a small volume.A good shape for pressure operation.Well- established fabrication techniques.It can be easily cleaned.

•U-TUBE HEAT EXCHANGER

STRAIGHT-TUBE HEAT EXCHANGER

ONE PASS TUBE-SIDE TWO PASS TUBE-SIDE

DOUBLE-PIPE HEAT EXCHANGER

•It is made up of concentric inner and outer pipe(sleeve pipe).

•Cold and hot liquid respectively flows in the gap of inner pipe and sleeve pipe and hence exchange the heat at same time.

•Inner pipe- use U-tube to connect. outer pipe-use direct pipe to connect both ends.

FEATURES:Structure is simple and heat transmission is large.Easy to clean and convenient to assemble and disassemble.Flow rate is appropriate and it is possible to have backwash.

PLATE HEAT EXCHANGER

•Use metal plates to transfer heat between two fluids.

•Fluids are exposed to much larger surface area because fluid spread out over the plates.

this facilitates the transfer of heat. increase the speed of temperature change.

GASKETED-PLATE HEAT EXCHANGER

•Consists of a stack of closely spaced thin plates clamped together in a frame.

•Thin gaskets seals the plates round their edges.

•These exchangers are used in food and beverage industries as they can be readily taken part in cleaning and inspection.

FEATURES:Plate thickness -0.5 to 3mm.Gap between plates-1.5 to 5mm.Plate surface area range-0.03 to 1.5mm.Plate width: length ratio-2 to 3mm.Maximum flow rate of fluid is limited –2500m3/h.

•Plate –heat exchanger

CONTINUE……..

ADVANTAGES….. DISADVANTAGES….

• Plates are attractive when material cost is high.

• They are easy to maintain.• Low approach

temperature can be used (as low as 1 degree C).

• They are more flexible.• They are suitable for high

viscous material.

• They are not in good shape to resist pressure (not suitable for < than 30 bar).

• Selection of suitable gasket is critical.

PLATE-FIN EXCHANGERSPlate-fin exchangers consist essentially of plates separated by

corrugated sheets, which form the fins. • They are made up in a block and are often referred to as matrix

exchangers; • They are usually constructed of aluminum and joined and sealed by

brazing. • The main application of plate-fin exchangers has been in the

cryogenics industries,• such as air separation plants, where large heat transfer surface areas

are needed.• They are now finding wider applications in the chemical processes

industry, where large surface area, compact, exchangers are required. Their compact size and low weight have lead to some use in off-shore applications.

SPIRAL HEAT EXCHANGER

•They are considered as plate heat exchanger in which plates are formed into a spiral.

•Channels are formed between the plates through which fluid flows.

• It is made up of long sheets-150-1800mm wide. and gap between sheets- 4-20mm.•Channels are closed by gasketed-end plates

bolted to an outer case.• inlet and outlet nozzles are fitted to the case

and connect to channels.

AIR COOLED:COOLERS AND CONDENSERS• Air-cooled exchangers should be considered when cooling water

is in short supply or expensive. They can also be competitive with water-cooled units even when water is plentiful. Frank (1978) suggests that in moderate climates air cooling will usually be the best choice for minimum process temperatures above 650 c, and water cooling for

• minimum processes temperatures below50 C. Between these temperatures a detailed

• economic analysis would be necessary to decide the best coolant. Air-cooled exchangers are used for cooling and condensing.

• Air-cooled exchangers consist of banks of finned tubes over which air is blown or drawn

• by fans mounted below or above the tubes (forced or induced draft).

AGITATED VESSELS Only small rates of heat

transfer is required.Storage vessels is used to maintaining the temperature of the liquids.It is also used to promote heat transfer in vessels.

FIRED HEATERS These are considered

when cooling water is in short supply or expensive.

These are used when high temperature and high flow rates are required.

Capacity of these heaters are

3 to 100MW. These heaters are

directly heated by the products of combustion of a fuel.

APPLICATIONS………

Process feed-stream heaters; 60% of the feed vaporized.

Reboilers for the columns used small size direct-fired units.

Steam boilers.

Reformers for hydrogen production.