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Utility Section - Society Of Textile Engineering

By Donald Jones,2014-09-30 07:13
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Utility Section - Society Of Textile Engineering

Engineering Department

    This section of Crescent Textile Mills includes the following divisions:

    ; Boiler House

    ; Compressor Unit

    ; Instrumentation and Calibration lab

    ; Mechanical Workshop

    ; Electric Distribution

    ; Power Generation Plant

    ; ISO

    ; Civil Department

     Boiler House:

     The Boiler House is another division of the Utility department . Its main purpose is to generate steam which is used in various departments of the Mill. The main components which are used in

    the generation of steam are :

    (1) Water Supply system

    (2) Feed Tank ( with water delivery system )

    (3) Boiler ( with Economizer in case of water tube boiler )

    (4) Fuel Delivery system (for boiler operation)

    (5) Steam Distribution system

     Water Supply and Feed Tank

    Water used for steam generation is `treated water i.e. its hardness ,TDS and other contaminations have been removed ( obtained from Water Section of CTM ) . The R.O. / Soft water is pumped to Feed Water Tank by multi-stage centrifugal pumps through piping system ( containing pressure and flow regulation valves operated manually or automatically ) .

    Feed Tank is a vessel containing water inlet and outlet system with a heating system .The main purpose of a feed tank is to heat water and raise its temperature nearly equal to its boiling point , so that a less quantity of heat is required to generate steam in the boiler . The Boiler House of CTM consist of two Feed tanks . Water is fed to these tanks from Water Section. In the tanks some chemicals are added which are :

    (1) Oxidizers, added to evolve excess of oxygen.

    (2) PH value maintainers (8 to 9 ppm ) .

    (3) Chemicals which don’t allow the suspended particles to settle

    down ( if any ).

    The water in the Feed Tank is heated by steam inside the tubes( generated in boiler ) , passing it through water or by waste gases of boiler ( i.e. Economizer which will be discussed latter ) . The water in the Feed Tank acquires a temperature nearly equal to 90 to o 95 ( C) after heating . Now this heated water is pumped to boilers by three 16-Stage centrifugal pumps by automatic valves .

Boilers types

    Boiler is a closed vessel whose main function is to generate steam . There are two main types of Boilers:

    (1) Water Tube Boiler

    (2) Fire Tube Boiler

    Boilers can be further classified depending upon their mode of operation , Fuel system , quality of steam they produce and the purpose for which steam is generated etc .

    The Boiler House of CTM consist of both Fire and Water Tube boilers .The specifications of these boilers are as :

    (1) Water Tube Boilers

     The `Boiler House` of CTM consist of one Water tube boiler . It is a brick type boiler ( usually water tube boilers are brick type ) . Its capacity of generating steam is 15 tons/hr and produces saturated steam at 50 psi pressure .It is operated manually .

    (2) Fire Tube Boilers

    The `Boiler House` of CTM contains two Fire tube boilers. These are package type horizontal boilers. These boilers are operated automatically. The capacity of generating steam for one is 15 tons/hr and for the other is 12 tons/hr ( produce saturated steam at 50 psi pressure ) .

Waste Heat Recovery Boilers

    The `Boiler House` of CTM also generates steam from the heat which is rejected by cooling water system of multi-cylinder engines of Power Generation unit . There are seven vertical type waste heat recovery boilers , which generates about 8 to 9 tons/hr of steam .

    Fuel Delivery system (for boiler operation)

    The fuel delivery system deals with the delivery of fuel to the boiler house of CTM . These Boilers can be operated on two types of fuel : (1) Natural Gas

    (2) Heavy Fuel Oil ( HFO )

Natural Gas

     Natural gas is supplied to the Mill by SNGPL . From the main line , natural gas is delivered to Boiler House by G.I. pipeline . The natural gas received at boiler house is having a pressure of about 20 to 22 psi . For boiler operation we need 2 to 3 psi of gas pressure , so we depressurize the natural gas by Regulator valves ( uses diaphragm and compression springs which forces the gas to slow down ) .

    To control the supply of gas to W.T. boiler mechanical operated valves are used .

    Solenoid valves are used to control the supply of gas for F.T. (automatic) boiler .

Heavy Fuel Oil (HFO)

     The HFO is reached in the Mill premises by oil tankers , where it is stored in large oil storage tanks . From these tanks oil is delivered to boiler house by small tanks ( mobile ) . In the Boiler House there are gear pumps which are used to pump HFO to boilers at pressure . These pumps also contains a system to heat oil ( in winter season ) and to filter the oil .

    We generally prefer to use natural gas as fuel of boiler instead of HFO , because natural gas is cheap as compared with HFO as 1 lb of natural gas produces 1000 BTU of heat and 1 lb of HFO produces 1700 BTU of heat but if prices are compared for 1 ton generation of steam 16 lit oil is used costing 600 Rs/-( approx.) whereas with gas this cost is nearly half . HFO is mainly used in a situation when there is a failure of gas delivery .

Steam Distribution system

    The steam distribution system deals with collection of steam and its distribution to different departments of Mill .

    Steam from waste heat recovery boilers installed at PG is brought to Boiler house by means of steam piping such pipelines are insulated so that the heat may not be wasted . The insulation material may be Thermo pore , cotton or any other material . The insulation material is packed in MS sheet .

    When the steam is reached at boiler house it is directed to steam distribution panel , from where it is sent to its application area . The steam distribution system also contains a system to recollect the non-consumed steam from the working areas . This non-consumed steam is converted into water ( when it loses heat ) and added again in Feed tank .

Usage of Steam

    The Boiler House of CTM produces saturated steam which is used in the following areas of Mill ;

    (1) Used in Spinning section for :

     Drawing the yarn ,

     To have desired level of moisture during process ,

     To wet the yarn for strengthening etc.

    (2) Used in Processing department for :

     Bleaching ,

     Drying and

     Finishing .

    (3) Also used for warming the departments in the winter season

(2)Water Section

    The Water section deals with the distribution of water to various divisions of the Mill as well as the residential area. Total consumption of water to Mill is 170 to 180 ton/hr (approx) . There are two main sources of raw water :

    1. Ground Water

    2. Canal Water

Treatments of Canal Water:

    The Canal water available , consists of contaminations like sand , soil & other organo metallic compounds. Now this water is filtered in two ways:

    1. By the addition of chemicals.

    2. By Filtration plants.

By the addition of chemicals :

    In this method two chemicals are added in the canal water , named as :

    ; Alum

    ; Megna flaw Lt-27

    These chemicals acts as precipitants and the contaminations settles down. After

    filtration this water is stored in open tanks. This filtered water can’t be

    drunk, because all the dissolved particles can`t be filtered.

     By Filtration plants :

     In this method water is filtered by means of plant called ` Sand

    Filtration Plant`. There are four filtration plants. Two`s capacity is 3360 m/hr and two`s capacity is 125 m/hr.

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Reciprocating Compressors

    Reciprocating compressors are also called Piston Compressors . They are positive displacement compressors involving piston motion in cylinder . In these compressors as piston moves down the air is sucked from air inlet . As the piston moves upwards the air trapped is compressed , after compression it is fed to air system form outlet . The Reciprocating compressors are may be of Single Acting or Double Acting type .

    In Single acting type one pulse of air is produced per piston stroke , whereas in case of Double acting type pulses of air are produced on both up and down strokes of piston .

    Multi-Stage Reciprocating Compressors are used where a high outlet pressure is required . In multi-stage compressors , between every stage Inter-Cooler is used to cool down the compressed air after every stage ( because compression causes an increase in temperature of fluid ) .

Screw Compressor

    The Rotary Screw compressor has two intermeshing rotary screws which rotate in opposite directions . as the screws rotate , air is drawn into the casing through the inlet port and into the space between the screws . Air is then trapped in a cavity between adjacent threads and the casing with the ends of cavity sealed by the screws intermeshing . As the screws rotate , the air is moved along the length of the screws and compressed as the space becomes progressively smaller . Compressed air then emerges from the discharge port .

Screw compressors may be Oil Flooded or Oil Free type .

    In Oil Flooded type oil is injected into the chamber to assist in sealing the clearance gaps between the screws and walls of the cylinder and between the screws . It also helps to dissipate the heat resulting from the compression of the air .

    With Oil Free type no internal air cooling takes place and air has to be cooled after it exits the compressor.

    Typically , single-stage rotary screw compressors can be used for 3pressure up to about 1000 kpa with flow rates of between 1.4 m/min 3and 60 m/min free air delivery .

Rotary Compressors

    The Rotary Vane Compressors have a rotor mounted eccentrically in a cylindrical chamber . The rotor has blades , the vanes , which are free to slide in radial slots . The rotation causes the vanes to be driven outwards against the walls of the cylinder . As the rotor rotates , air is

    trapped in the pockets formed by the vanes and as the rotor rotates so that the pockets become smaller and the air is compressed . Compressed pockets of air are thus discharged from discharge port. Oil is injected into the chamber to assist in sealing the clearance gaps between the vanes and walls of the cylinder and between the vanes and the rotor . It also helps to dissipate the heat resulting from the compression of the air.

    Single-stage Rotary Vane compressors typically can be used for pressures up to about 800 kpa with flow rates of the order of 0.3 33m/min to 30 m/min free air delivery .

    The air leaving the compressor can be hot and contain contaminations such as oil from compressor , moisture and dirt particles . So it is then passed through Air Treatment Chamber , which consist of following components :

    (1) After - Coolers

    (2) Dryers

    (3) Filters

    (4) Pressure Regulators

    After Coolers are heat exchangers similar to intercoolers . They can be either Air-Cooled or Water-Cooled .

    A Water Cooler consist of essentially of a series of pipes through which the cooling water flows , the air moving through the space round the pipes and so becoming cooled .

    The aim of Dryer is to reduce the amount of water vapours in the compressed air to a level which will prevent condensing out in the system supplied with the compressed air .

    There are three main types of Dryers :

     Chemical Absorption Dryer

    Adsorption Dryer

    Refrigeration Dryer

    Filters are used to remove dirt before the air enters a compressor . Such filters can be Dry Filters with replaceable cartridges or Wet Filters where air is bubbled through an oil bath and then passed through a wire mesh filter . The air particle become attached to the oil drops and are removed by the wire mesh .

    Generally the air pressure from the supply is set to be greater than that required for a pneumatic system and pressure regulation is used to keep the pressure constant regardless of the flow . a pressure

    reducing valve , termed as a Pressure Regulator , is used for this

    purpose. They occur in two basic forms:

    Non Relieving Pressure Regulator

    Relieving Pressure Regulator

    The Compressor House of C.T.M consist of following Compressors ( along it there specifications are also given ) .

    Capacity Cooling Type Model Maker Compress

    (mSystem or

     No.

    Air - Cooled Oil Flooded Sirius Comp air 1

    Screw 132/9a

    Air - Cooled Oil Flooded Sirius Comp air 2

    Screw 132/9a

    Air - Cooled Oil Flooded ESD 301 Kaeser 3

    Screw

    Air - Cooled Oil Flooded ESD 301 Kaeser 4

    Screw

    Air - Cooled Oil Flooded ESD 301 Kaeser 5

    Screw

    Water- Oil Free ZR 110/W Atlas 6

    Cooled Screw Copco Remarks Motor 9.0WorkinMotor Water- Centrifugal C15MX2-Ingersol 7 Rpm g Power /min) 3Cooled 2SH Rand Pressure (kw)

     (bar)

    Water- Centrifugal C15MX2-Ingersol 8 - 1500 9.0 132 22.7 Cooled 2SH Rand - 1500 9.0 132 22.7 - 1500 8.5 160 30.0 - 1500 8.5 160 30.0 - 1500 8.5 160 30.0 Dryer is vapor 2980 9.0 110 15.4 adsorption type

    Compressor & 2965 8.5 132 13.3 Dryer efficiency

    is low

    - 2965 8.5 132 13.3

     Usage of Compressed Air :

    Compressed Air has a wide application in a Textile Mill . In C.T.M. Compressed Air is used in the following departments :

     Used in Spinning division for Operation of different machines like

    o Air Jet spinning ( MJS ) .

    o Auto Cone Winder .

    ; For Splicing .

    ; Also used for cleaning of Machines .

     Used in Weaving division for Air Jet Weaving .

     Used in Processing for operation of Rollers and Dryers .

     Used for Sand Blasting .

     Also used for Air Signaling .

Instrumentation & Calibration Lab

    Unlike other Textiles Mills , Crescent Textile Mills have developed an Instrumentation & Calibration lab . This is a multi purpose lab comprising of two sections :

    (1) Instrumentation Section

    (2) Calibration Section

Instrumentation Section

    The Instrumentation Section is basically performing the duty of repair and maintenance of out - of - ordered electronic components of different machines. The lab deals with the faulty components , regarding to Semi conductor and Power Semi conductor devices . he lab has the facility to

    deal with all types of Electronic Cards ( for repair and maintenance ) .In the lab there are available all semi conductor devices as a stock for changeover during repairing. The lab is equipped with all types of analyzers like Oscilloscopes ( for wave analysis ) , Function generators ( for frequency analysis ) , Digital multi-meters , Tong testers etc . The lab has also the ability to produce Bye-pass components during failure of main components of a machine , i.e. it can make electronic cards / modules by it self also .

    In this way the Instrumentation lab is acting as a Booster for mass production . Because whenever there is a fault in an electronic component of machine it is sent to the lab in no time . the faulty component is repaired in minimum time . In this way precious time is saved . Whereas if there isn`t any such lab , a considerable time is taken during its transportation to repair centre , as well as economics is concerned .

Calibration Section

    The Calibration lab of C.T.M is one of its own kind in the textile industry in Pakistan . This lab has the facility to calibrate various types of instruments and measurers , like Vernier calipers , Micro meter screw gauges , Pressure gauges ( hydraulic and pneumatic ) , Temperature sensors , Humidity sensors ( Hygrometer ) , PH tester , TDS tester etc .

Mechanical Workshops:

    The Mechanical Workshops is one of the important departments of Engineering division of Crescent Textile Mills . Their main purpose is to provide Repair and Maintenance facilities to different departments of the Mill .

    Under Mechanical Workshop the following sub-divisions are working

    (1) Machine Shop ( main division )

    (2) Fitting Shop

    (3) Wielding Shop

    (4) Foundry

    (5) Casting

    (6) Carpentry and Painting Shop

    Among these the Machine Shop is the main shop performing multi functions.

Machine Shop

    Machine Shop is a multi tasking shop dealing with most of repair and maintenance work . In the machine shop of C.T.M. the following machines are installed :

    ; Lathe Machines

    ; Milling machines

    ; Shapers

    ; Grinding Machines

    ; Drilling Machines

Carpentry and Painting Shop

    In Carpentry shop wood is processed for required products . In CTM the main objective of carpentry shop is to make door , windows foundations of some machines , tables , chairs etc .

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