ENERGY CONSERVATION IN THE SPINNING INDUSTRY: MUST FOR SURVIVAL

R.Senthil Kumar, Senior Lecturer, Deptt. of Textile Technology, Kumaraguru College of Technology


ABSTRACT:

Textile industry is the second largest industry in the world next to agriculture. In India, the textile industry contributes substantially to the foreign exchange earned by the country. The Indian textile industry is estimated at $52 billion. In the XI Five Year Plan, textile industry was expected to grow at 16% per annum and attain a size of $115bn by 2012. The need of energy conservation has assumed paramount importance due to the rapid growth of industries causing substantial energy consumptions in textile operations. Global energy crisis, as well as high cost of fuels resulted in more activities to conserve energy to maximum extent. The textile industry retains a record of the lowest efficiency in energy utilization and is one of the major energy consuming industries. About 34% of energy is consumed in spinning, 23% in weaving, 38% in chemical processing and another 5% for miscellaneous purposes. The emphasis on awareness about the energy conservation is essential in the present circumstances. In order to promote energy conservation in spinning industry, this paper analyzes in detail the actual conditions of energy consumption in each department and measures for energy conservation in each area of spinning industry.


MANUFACTURING COST OF YARN IN SPINNING MILL:
In today's competitive market, competing with other manufacturers depends on producing high quality yarns with reasonable costs. The cost of yarn consists of several factors such as raw material, energy or power, labour, capital etc. The cost of yarn excluding raw material is termed manufacturing cost.

Table 1. Manufacturing cost of 20 Tex cotton combed yarn in various countries

The share of the factors in manufacturing cost changes according to the yarn properties, machine operational properties and economical situation of the spinning mill. Raw material (fibre) forms nearly half of the yarn's total cost and other cost factors such as labor, energy, capital cost of machines, auxiliary material cost and waste make up the remaining part. After raw material, capital and energy costs have the highest proportions in the total. Energy is necessary for each step of spinning processes to drive machines, air conditioning and lighting, but the highest energy consumption occurs during the spinning process in spinning machines.
ENERGY DISTRIBUTION IN VARIOUS MACHINES IN SPINNING PROCESS:

Fig 1 Energy distribution in different machines of spinning process

Energy is generally used for operating machines, air conditioning and illuminating the atmosphere where yarns are manufactured in spinning mills. In addition to these, compressors which provide compressed air to the spinning line use energy. Ring spinning system consumes more energy than any other spinning systems. Energy consumed to drive the spindle will constitute nearly 85% of the total power consumption in the ring frame machine. It will depend upon the details such as yarn count, package size and spindle speed. The remaining energy is consumed by drafting and lifter mechanism.
MAJOR AREAS TO CONSERVE ENERGY IN YARN MANUFACTURING PROCESS:
• Ring frame
• Humidification process
• Electrical distribution network
• Lighting systems
• Compressed air distribution
RING FRAME:
• In ring spinning frame, spindles consume about 30% of the energy consumption. Lighter (from 320 g to 265 g) and lower wharve diameter (from 25 mm/ 22.5mm to 18.8mm) spindles consume about 10% less energy with lower speed operation of tin roller shaft.
• Rewound motors reduce motor efficiency. No load tests should be conducted on motors during energy audits. These no load tests are an indication of the rewinding quality of the motors. Typically, the no load current of a motor is about 35-40% of the full load current.
• To improve the efficiency of motor for the given motor & load characteristics, it is advisable to bring down the motor body temperature for better efficiency.
• During a typical energy audit, the operating parameters of the motors like operating current, voltage, power factor and the running kW is measured using sophisticated instruments.

HUMIDIFICATION SYSTEM:

Humidification system creates amiable atmosphere to the machines and operatives.
Automatic humidification system consumes 25% to 35% of the total mill power.

• Usage of High Efficiency FRP fans (properly sized to the air throw & CFM specifications and installed correctly) instead of M.S. or Aluminum blades consume less power input for the given air output.

• Supply Air System:
 Attic Ventilation is to be provided to reduce transmitted heat through the roof.
 False ceiling is to be insulated.
 False ceiling height should be minimum 4.25 meter (14 ft.) from floor level to improve the uniform air circulation.
 V-Shape fresh air filter can be provided for reducing fluff accumulation inside the supply air system.
 Sufficient size of fresh air damper will improve plant efficiency.

• Return Air System :
 Return air trenches should be designed with minimum corners and bends and should be given a smooth finish to reduce air-resistance.
 Rotary return air drum filters with effective suction fan for continuous fluff removal will help to keep the return air filters clean and reduce air
resistance, thereby reducing power consumption of return air fan motor.


• Under deck Insulation :
 Generally, industrial roofing is of asbestos cement sheets or metal sheets (GI / Aluminum) and under deck insulation with minimum 50 mm thick resin bonded glass wool of 32 kg/m3 density is necessary to reduce the heat gain through the roof and minimize the attic temperature rise within the false ceiling.

• Use of PVC air inlet louvers and eliminators :
 With PVC blades and moderate air velocity (not exceeding 600 fpm for low velocity air washer system and not exceeding 1200 fpm for high velocity air washer system) are desirable to reduce the air resistance in the air washer with consequent reduction in design static pressure for supply air fan selection so as to reduce fan motor power consumption.

• Use of variable speed drive:
 Use of variable speed drive (inverter control) on air washer water circulation-cum-spray pumps, helps to achieve power saving on part load operations. However, variable speed drive for fan motors is generally not adopted since any reduction in air flow can slow down the removal of fluff and other waste materials and contaminate the department causing quality deterioration of the yarns / fabrics inside.

ELECTRICAL DISTRIBUTION NETWORK:
• Cable Losses:
 The cable losses are directly proportional to the length. The losses are proportional to the square of current. Hence for energy efficient electrical design the main concept in the mind should be that there will be minimum cable length. Hence the selection of panel board position and main panel room and transformer location is very important.

• Power Factor:
 By incorporating automatic PF control panels to achieve maximum power factor.

LIGHTING:
Lighting system constitutes about 4% of the energy consumption in mill. Electricity saving fluorescent lamps, with 70-80 lux/watt, have much higher luminous efficiency than tungsten ones with 10-15 lux/watt. The effectiveness of illumination is also affected by various other factors such as the layout of the working area, the colour of the interior and the distance of the light source to the illuminated area. Other lighting saving measures may include turning off lights, computers and printers when not in use, particularly after office hours. In one plant, this has helped to reduce lighting bills by around 15% a year.
Table 2 : Lamp Characteristics from Energy star Upgrade Manual for Buildings,Dec2004


 Standard illumination level in preparatory section is 40-50 lux and in ring frame section is 75-100 lux and in winding section is 100-125 lux.
 LT servo stabilizer of suitable capacity is recommended in the main lighting feeder with the set voltage of around 200V. This measure ensures a saving of about 10%.
 The conventional copper ballasts can be replaced with electronic ballasts to save about 20% of energy.



COMPRESSED AIR SYSTEM:

One of the important ancillary section in modern spinning mill. This section consumes nearly 6% of the total mill energy consumption. Due to highly automated machines we require high air requirement satisfied by centrifugal compressor.

• We can expect up to 5% of energy saving by centralizing compressor of higher capacity and higher efficiency. This is due to lesser friction losses.
• Use of required pipe size, minimum right angle bends, reduces friction loss.
• The design should ensure that the pressure drop should not be more than 0.5 Kg/cm2 (7 Psi) in the longest line.
• Clogging of filters create chocking of filter leads to drop in suction pressure which reduces compressor efficiency.
• Avoid placing the compressor in hot environment which rises the inlet air temperature increases the energy consumption.
• Moisture in compressed air leads to corrosion in pipe lines increases internal resistance creates more pressure drop affects efficiency of compressor.
• Maintain proper tension of the driving belt which saves sufficient amount of energy.
• The components of the compressor such as piston, piston rings, bearings and valve gears to be maintained with proper lubrication.
• Excess friction due to worn out parts or lack of grease leads to higher power consumption.
• The oil level in the compressor is to be maintained properly.
• The compressed air pipeline system should not have any air leakages.
• Pressure guns to be provided to avoid wastage of compressed air.
• When the compressed air pipelines were not maintained properly, a maximum of 15% of power loss has been noticed in the mills.

CONCLUSION:
The energy cost in increasing at a faster pace and is the largest conversion cost accounting for about 10% of the sales and almost 5 times the net profit margin of a spinning mill. The three major factors for energy conservation are high capacity utilization, fine tuning of equipment and technology upgradation.With more and more utilization of electrical energy and faster growth of industries, the impetus of energy conservation is increasing by leaps and bounds. Today, energy conservation is a must for survival: that is a much more powerful imperative. As prices - for materials and finished products - are increasingly dictated by global markets, what remains within our control is conversion cost and energy costs are perhaps our greatest opportunity for cost reduction in the country today.
REFERENCES:
1. http://www.energymanagertraining.com/textiles/pdf/Energy%20savings%20audit%20in%20textile%20industry.pdf.
2. Second stage energy conservation experience with a textile industry – C.Palanichamy and N.SundarBabu,Energy Policy, Volume 33, Issue 5, March 2005, Pages 603-609.
3. Handy manual-Output of seminar on Energy Conservation I Textile Industry.
4. An Investigation on Energy Consumption in Yarn Production with Special Reference to Ring Spinning- Erdem Koc,Emel Kaplan, Cukurova University, Turkey.
5. Energy Conservation –Time to get specific II edition A CII study conducted by Forbes Marshall.
6. Humidification for Textiles Mills by M.M.Roy,Air conditioning and Refrigeration journal , January-March 2005.
7. SITRA Energy Audit –Implementation Strategy in Textile Mills ,K.R Chandran and P.Muthukumarasamy, SITRA Coimbatore-14 (website).


Author Profile:
R.Senthil Kumar,
Senior Lecturer,
Department of Textile Technology,
Kumaraguru College of Technology,
Saravanampatty post,
Coimbatore – 641006.
Tamil Nadu, India.
sen29iit@yahoo.co.in
mobile No: 9677468590