Role Of Compressed Air System In Textile Industries

 Compressor used in Textile Industry Optimization of Air System  Minimizing Compressed Air Cost...  Compressed air, also referred to as the "4th Utility" after electricity, water & s

Role of Compressed Air System

in Textile Industries

UNIVERSITY OF KARACHI

CHEMICAL ENGINEERING

AELYA SHAH

 Compressor used in Textile Industry

 Optimization of Air System

 Minimizing Compressed Air Cost

 Compressed air, also referred to as the

"4th Utility" (after electricity, water & steam) is one of the major energy consumption utility in any industry

 Various estimates indicate that about 5,000 MW is consumed nation wide by the

4,000-compressors and its related accessories &

support systems

 It is a well-known fact that of the life cycle cost of any compressor, 85-90% is towards energy and only 10-15% towards initial investment & maintenance.

 Hence, the design and selection of the right

compressor assumes great significance while

setting up your air system It is very important on the part of each one of us using compressed air to

understand a simple fact that "Air is free but

compressed air is not!"

Use of Compressed Air in

Textile Industry

In Textile manufacturing units, generally

following Compressed air powered pneumatic systems are used:

 Spinning machine (for control purpose through valves and cylinders)

 Loom Jet Weaving (for the insertion of weft)

 Winding machine (for the purpose of splicing of yarn)

Use of Compressed Air in

 Sewing Needle

 Conveying

Applications

Compressed Air System

The compressed air system mainly consists of:

•Supply side

•Distribution &

•Demand side

 Compressed air systems consist of a supply side,which includes compressors and air treatment

 and a demand side, which includes distribution and storage systems and end-use equipment

 A properly managed supply side will result in

clean, dry, stable air being delivered at the

appropriate pressure in a dependable, cost-effective manner

 A properly managed demand side minimizes

wasted air and uses compressed air for

appropriate applications

Compressed Air System

compressed air sub system

As such the compressed air system has following six major sub systems

 The compressed air generated by compressor

is stored in the Air-receiver of sufficient capacity

to smoothen fluctuations in the supply of

compressed air vis-a-vis demand from

individual consumption points (machines)

The air receiver helps also in cooling of air and this facilitates removal of much of the moisture

in the air which is harmful for the pneumatic

system

Air-receiver

 For large users/bigger compressors air dryer units are provided.

 The air dryer units of two types are

normally employed in the mills

1.heatless dryer

2.refrigerated air dryer

Air-dryer

 Although, the refrigerated air dryer has

higher initial cost, it has less operational cost than the heatless type This is because in

heatless dryer about 10-12% of compressed air is lost in purging thereby wasting costly electrical energy

 The air dryer helps in making the

compressed air almost 100% dry – which is essential for some machines such as Air jet looms

Air-dryer

 As regards air distribution network, it

should be ensured that pressure drop should not be more than 0.5 kg/cm2in the longest line

 The pipe sizes are to be decided based on this consideration Also the pipe lines should

be of minimum length with less bends and fittings

 This will ensure minimum wastage of

electrical power

Air distribution

 For the proper and trouble free operation

of pneumatic systems provided for the

machines, it is essential to ensure filteration, pressure regulation and lubrication of the

compressed air

 The filteration is ensured by providing

filters in the pipe line after the air receiver These can remove dust particles upto 5

micron size

Air filter

 Pressure regulation i.e maintaining the desired air pressure for the machines used

is achieved by the use of air pressure

regulator

Pressure regulation

 For reducing friction and wear

and tear and preventing corrosion,

proper lubrication of compressed

air is necessary This is achieved by

the ‘oil-fog’ air line lubricator

Lubrication

TYPES OF COMPRESSOR:

Positive-Displacement

Compressors

 In the positive-displacement type, a given quantity of air or gas is trapped in a

compression chamber and the volume which

it occupies is mechanically reduced, causing

a corresponding rise in pressure prior to

discharge At constant speed, the air flow

remains essentially constant with variations

in discharge pressure

Reciprocating compressors

 It work like bicycle

pumps 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

 Double-acting reciprocating compressors

are generally water-cooled and with

multi-stage versions are usually considered to be the most efficient air compressors (100 hp to 250 hp) These however, come with high initial &

installation costs and higher maintenance as

Screw compressors

 Screw compressors are available as

oil-flooded (lubricated) single or multistage

(generally from 15 hp to 500 hp) but have lower operating efficiencies at part-loads and also

high unload power, which could become the

key factors in reducing your operating

efficiencies However, incorporating VFD

(variable frequency drive) or HPM motor

(hybrid permanent magnet) would make these compressors efficient throughout the operating range

 Advantages of the rotary screw compressor include smooth, pulse-free air output in a

compact size with high output volume over a long life

Dynamic compressors

 Dynamic compressors impart velocity energy

to continuously flowing air or gas by means of impellers rotating at very high speeds The

velocity energy is changed into pressure energy both by the impellers and the discharge volutes

or diffusers

 In the centrifugal-type dynamic

compressors, the shape of the impeller blades determines the relationship between air flow

and the pressure (or head) generated

Centrifugal compressors

 A centrifugal air compressor has a

continuously flowing air stream which has

velocity energy, or kinetic energy, imparted to it

by an impeller, or impellers, which rotate at

speeds that can exceed 50,000 revolutions per minute (rpm)

 Three stage centrifugal compressors

available in the market would give much higher efficiencies generally 10-15% more than the two stage positive displacement types

 Moreover, features like 100% oil-free air,

constant pressure, high turndown abilities with good part-load efficiencies, nil wear & tear,

much lower maintenance costs have made this compressor very popular with all users

 These are available from 250 hp to 5,000 hp and upward as well

Compressor used in Textile

Industry:

 Reciprocating type of compressors were normally in use in the textile industry

 However, of late screw compressors are being

preferred as these are more energy efficient as compared

to reciprocating compressors

 For very high capacity requirements centrifugal

compressors are used In fact, for many large textile

units who have been using positive displacement

technology for the last 5-10 years or above can ideally

look to incorporate the centrifugal technology, which will have payback of less than 2 years in most cases.

Capacity range of air

compressors

The compressor capacity is stated in terms of cfm i.e cubic feet per minute of air (being compressed or free air

delivery) Capacity range of air compressors normally used

in the industry is as follows:

Type of Air Compressor Capacity Range (cfm)

Reciprocating Compressor, Single

Stage

Upto 50 cfm Reciprocating, Two Stage 50-600 cfm

Screw Compressors 150-2500cfm

Centrifugal Compressors 2000-4000cfm

Optimization of Air System

The six steps to optimize an air system are

2 Establish the leakage in your system and

proactively manage the same

3 Analyse the System Capacitance & optimize the same

4 Track the pressure profiles across the plant

to match the supply & demand and also

minimise the pressure drops

Minimizing Compressed Air Cost

 Compressed air cost can be minimize

broadly in two ways

1 By minimizing wasteful consumption of

compressed air i.e by preventing

compressed air leakages

2 By improving the efficiency of

compressors