UTILITIES USED IN TEXTILE INDUSTRY

UNIVERSITY OF KARACHICHEMICAL ENGINEERING

UTILITY DEFINITION:Utility provide services to industry processes.

UTILITIES SECTION:

UTILITIES SECTIONUtilities section is the

department which supply

Electricity Steam Water Compressed air

1.ELECTRICITY:Electricity is used to run the machine in industry. It is

power source for machinery.

2.STEAM:Steam is the vaporized state of water which contains heat

energy and transfer that energy into a variety of processes in textile industry.

Boilers are the common installation in utility plants to produce steam.

Applications in textile industry:In textile industry Steam is used for fiber production,

weaving , dyeing , drying , printing, heating the equipment and maintaining the temperature of system.

BOILER:A boiler is basically a closed vessel into which water is heated until the water is converted into steam at required pressure.

Classification of Boilers: Boilers can be classified as follows: 1. According to relative position of water and hot gases 2. According to geometric orientation of boiler3. According to location of furnace4. According to method of water circulation5. According to working pressure6. According to mobility of boiler 7. According to number of tubes in the boiler

1.According to relative position of water and hot gases a) Fire tube boilers; If the hot gases of combustion from the furnace

pass through the tubes and water is surrounding the tubes is called fire tube boilers.

b) Water tube boiler; If the water passes through the tubes and hot gases surrounding the tubes is called water tube boiler. Water Tube Boiler Fire Tube Boilers

2.According to geometric orientation of boiler a. Horizontal boiler; If the axis of boiler is horizontal is called

Horizontal boiler. b. Vertical boiler; If the axis of boiler is vertical then it is called

vertical boiler. c. Inclined boiler; If the axis of boiler is inclined then it is called

inclined boiler.3.According to location of furnace d. Externally fired boilers; In this boiler the furnace is placed outside

the boiler shell. Generally water tube boilers are externally fired. e. Internally fired boilers; In this boiler the furnace is placed inside

the boiler shell. Generally fire tube boilers are internally fired. 4.According to method of water circulation f. Natural circulation boilers; In this boiler, water flow take place

naturally, by density difference of water. The flow of water and steam are set up due to density difference resulting from difference in temperature.

g. Forced circulation boilers; In this boiler, water flow takes place by a pump.

5.According to working pressure a. High pressure boiler; The working pressure of this boiler

is higher than 25 bar. b. Medium pressure boiler; The range of working pressure

of this boiler is between 10 bar to 25 bar. c. Low pressure boiler; The range of working pressure is

between 3.5 to 10 bar. 6.According to mobility of boiler d. Stationary boiler; This boiler cannot be moved easily

from one place to another place. This are used in power generation or process heating in industries.

e. Mobile boiler; It is easily moved. 7.According to numbers of tubes in the boiler f. Single tube boiler; This boiler having only one fire or

water tube for circulation of hot gases or water. g. Multi-tube boiler ; This boiler having two or more fire or

water tubes for the circulation of hot gases or water.

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3.WATER :The textile industry consumes large amount of water in its varied processing operations. In textile wet processing, water is used mainly for two purposes.Firstly, as a solvent for processing chemicals and Secondly , as a washing and rinsing medium. The quantity of water required for textile processing varies from

mill to mill depending on fabric produce, process, equipment type and dyestuff.

The longer the processing sequences, the higher will be the quantity of water required.

Bulk of the water is utilized in washing at the end of process. In the mechanical processes of spinning and weaving, water

consumed is very small as compared to textile wet processing operations, where water is used extensively.

Water consumption in Textile industry

COOLING TOWER:A Cooling tower is a heat rejection device which

removes waste heat to the atmosphere through the cooling of a water stream to a lower temperature.

Cooling towers use the evaporation of water toremove process heat and cool the working fluid.

Cooling towers remove excess heat from large structures; heat that is the product of machinery, processed material, and mechanical processes.

The main purpose of cooling towers is to cool the circulating water used in these structures.

Classification Of Cooling TowerOn the basis of air flow:1.Natural draft No external mean required to force or draw air through the tower.2.Mechanical draftUses power-driven fan motors to force or draw air through the tower.i. Induced draftii. Forced draftOn the basis of air-to-water flow1.Cross flow 2.Counter flow

Mechanical draft:It is divided into two types:

i) In induced draft cooling towers, the fan is mounted at the top of the tower and is used to "pull" air through the tower.

ii) In forced draft cooling towers, the fan is mounted on the side of the tower and is used to "push" air through the tower.

On the basis of air-to-water flowi) In cross flow cooling towers, the air enters the side of the tower and travels perpendicularly to the water stream.

ii) In counter flow cooling towers, the air enters at the bottom of the tower and travels up in the opposite direction of the water stream. The induced draft counter flow cooling tower is

probably the most common.

4.COMPRESSED AIR: Compressed air is a form of stored energy that is used to

operate machinery, equipment, or processes. Air compressor , used to produce compressed air.

Application In Textile Industry:  Compressed air is used mainly as a motive force to actuate

the process control valves and machines in a textile mill. It is also used for loom jet weaving, spinning , texturizing.

AIR COMPRESSOR A compressor is a machine that is used to increase the

pressure of a gas.

Compressor

Positive displacement

Reciprocating Centrifugal Axial

Dynamic

Rotary

Classification Of Air Compressor

1.Positive-displacement Compressor In the positive-displacement type, a given quantity of air is trapped in a compression chamber and the volume it occupies is mechanically reduced, causing a corresponding rise in pressure prior to discharge.

a. Reciprocating Compressor A piston, driven through a crankshaft and connecting rod by an electric motor, reduces the volume in the cylinder occupied by the air or gas , compressing it to a higher pressure.

b. Rotary compressorRotary compressors have rotors in place of pistons

and give a continuous discharge. The most common type of rotary compressor is

screw-type.Rotary screw compressor consists of two

intermeshing rotors, screw-rotors mesh, trapping air, and reducing the volume of the air along the rotors to the air discharge point resulting in increased pressure.

2.Dynamic Compressors These compressors raise the pressure of air by imparting

velocity energy and converting it to pressure energy. a. Centrifugal Compressor The centrifugal-type is the most common and is widely used

for industrial compressed air. A centrifugal air compressor has a continuously flowing air stream which has velocity energy, imparted to it by an impeller. Approximately one half of the pressure energy is developed in the impeller with the other half achieved by converting the velocity energy to pressure energy as the air speed is reduced in a diffuser and volute.

B. Axial Compressors Axial compressors consist of a rotor with multiple rows of

blades and a matching stator with rows of stationary vanes.

The rotating blades impart velocity energy, primarily in an axial plane. The stationary vanes then act as a diffuser to convert the residual velocity energy into pressure energy.

BOILER WATER TREATMENTThe primary function of a boiler water treatment

program is to keep heat transfer surfaces free from scale and deposition.

 Boiler deposits are problematical, as they typically contain undesirable levels of metal oxides, mineral scale, sludge, or various combinations.

Boiler water treatment is used to remove suspended solid , dissolved solid and dissolved gases.

The steps that are used to purify water before it goes to boiler are:

1. Filtration to remove suspended solid2. Reverse osmosis to remove dissolved solid3. Deaeration to remove dissolved gasses1.Carbon filterA pressure vessel, filter bed of various sizes of gravel,

sand, and anthracite coal is usually sufficient to reduce suspended solids to acceptable levels.

It remove some particles that cloud the water, reduce nasty chlorine residue and can even help to reduce odors, thus improving the general taste and clarity of water.

2.Reverse osmosis RO involves separating water from a

solution of dissolved solids by forcing the water through a semi-permeable membrane.

3.DeaeratorTo reduce corrosive dissolved gases we use a deaerator.

Deaerators exploit the physical properties of temperature and pressure to drive off dissolved gases.

The water introduced in a deaerator is sprayed in to the tank just to remove the dissolved corrosive gasses( Hydrogen (H2S) ,Carbon dioxide (CO2), Oxygen (O2))properly.

The water inside the deaeration tank is heated to 100 centigrade temperature but the pressure is also exerted to stop boiling phenomenon.

Once the gasses are forced out of solution they are vented off.

Now , treated water can be supplied into boiler.

Gasses vent off