The implementation of energy conservation programmes in spinning mills has gained wide acceptance in the back-ground of the rising cost of energy. With more and more utilisation of electrical energy and faster growth of industry, the impetus on energy conservation is increasing by leaps and bounds. The pressure of energy bill and pressure on the total available energy is very much needed for further development.
The most important thing is conversion of electrical energy into mechanical energy.
Normally the conversion efficiency is 85%. But even 1% increase in this figure will reduce the energy bill by millions of rupees. Today 85% of the industrial loads are driven by electric motors. Out of this induction motor itself constitutes 30o of the total drive system. So the thrust has been given on the loss minimization control of induction motor drives and energy saving to the maximum level possible extent in a spinning mill using systematic approach.
The three major factors for energy conservation are high capacity utilisation, fine-tuning of equipment and technology upgradation. In this paper it is decided to apply the above three concepts to the maximum extent.
The methodology adopted for conducting the detailed energy audit is as follows:
· Basic data collection on list of power consuming equipment, production capacities of the major equipment and operating parameters.
· Measurement o) operating parameters of various equipment to estimate their operating efficiency.
· Analysis of data collected and measurements to develop specific energy saving proposals.
· Presentation on the findings of the detailed energy audit.
Description of plant
· Yarn manufacturing operation using state-of-the-art textile equipment.
· Daily spinning capacity is 10,000 kg of yarn and number of spindles are 45,072.
· Operating hours per day is 24 hours and operating days per year is 356.
· Electrical energy and liquid fuels are used.
· Major energy sources are electricity and HSD.
· Break-up of the energy consumption:
Source Quantity Rupees
Electricity 92 49 253 3 42 22 236
HSD 3698836 11836274
· Contract demand with TNEB is for 1800 KVA per month.
Major consumption points:
* Humidification plant
* Blow room
* Heating lamps
Here the cottons (or other fibres), which are received in bales, are opened up mechanically. The fibres from different bales are blended at this stage. Air current is blown in order to separate cotton fibres and to remove dust, sand, dirt, leaves and seed particles. The output from this section is in the form of lap or sheet is fed directly for the carding stage.
This process forms a thin web of fibre, which is condensed into a rope called slivers. The carding machine essentially consists of a series of cylinders, which have wires mounted on them and which rotate counter to each other. This action results in the complete opening of the fibre tufts, thus cleaning the fibre thoroughly. Certain extent of parallelisation of fibres also takes place at this stage in addition to increasing the uniformity per unit length.
This process is only used for processing long staple fibre to make finer yarn counts. Several carded slivers are drafted together to form a small lap. These laps are taken into the comber, where the fibres are combed through final metal teeth. Combing also includes fibre alignment. The combed fibre is again condensed into sliver and taken to the draw frame.
In this process, carded or combed sliver is drawn in order to impart uniformity and parallelise the fibres in the longitudinal direction. Depending on the count for the yarn to be spun a sliver may be drawn once, twice or thrice.
This is a conventional spinning process for medium and fine counts. The drawn sliver is fed to a "speed frame", then to an inter and finally to the "ring frame". In the ring frame the roving (the output of the speed frame) passes through gear driven drafting rolls, a yarn guide and through a rotating c-shaped traveler before being wound on the bobbin which is mounted on a rotating spindle.
The bobbins from the ring frame are small in size and hold too low a quantity of yarn to facilitate continuous running of subsequent machines. Hence, this yarn is wound into larger packages conical or cylindrical.
Energy audit process
The energy audit process follows:
· Identification of machines is done by measuring power rating of the load and type of load.
· Information about machines includes method of power transmission, loading sequence sources of energy wastage and method of control.
· Energy vs power rated is used for selection of machines for detailed energy audit.
· For creation of methods for conservation following points were considered: Alternate to reduce/avoid energy losses.
· Alternate to reduce down time.
· Alternate to optimum selection.
Power consumption in a spinning mill
The goal in the analysis of data was to be able to show what has been occurring in their areas. This data help them to recognise that they could do something that would make their area more energy efficient.
The spinning operation uses 45.45% of total energy. The second largest use of energy (12.5%) is humidification plant. The heating lamp used 9.67% of the total energy, carding used 7.54% energy and winding used 6.29%. The remaining energy was used by drawing, simplex, doubling, lighting and others.
Energy factors in the selection of electric motors
Choosing a motor most suitable for a particular application is based on many factors including the requirements of the driven equipment, service conditions, motor efficiency and motor power factor. In the textile sector, electrical motors consume about 90 to 95% of total electric power. Good energy management is the application of the motor and its components that results in the least consumption of energy.
Findings and recommendations
· Spinning department consumes 45% power and hence various steps are proposed to reduce the power consumption.
· The second largest energy consumption is by humidification plants and about 12.3% these plants are running round the clock.
· Total lighting consumption of the plant is 1.65%; most of the fittings are tubelights.
The loading at various departments and how these deviate from SITRA standard (60- 80%) load. The yarn waste as per cent of yarn production should not exceed 0.25% and sweep waste with 1.5%. Considerable environmental and energy savings can be made by reuse of these waste materials. Such usage conserves both energy and resources by reducing the need for quarrying of new raw material and associated processing and transport cost.
Observe the basic condition of machine and number load power of all ring frames with standard power consumption. Machines consuming more power were attended.
Spindle of ring frames consumes 45% of power. A number of manufacturers have nowadays developed energy saving spindles having less weight and small wharf diameter. It was observed that 10 to 19% saving of energy is possible by using energy saving spindles.
Spindle is the high consumer of energy and the effect of the weight of the tape on energy consumption is more. Economics of SITRA energy saving tape with respect to the least expensive laminated is brought out. The SITRA energy saving tape gives a good return energy saving of 41.21% per tape compared to the least expensive laminated synthetic TAPE.(11)
Replacing conventional air washers with fabric cell type air washers will reduce the power consumption of the pumps. (TERI suggested savings for pumps using fabric cell type air washers in place of conventional air washers).
Total load lighting of the plant is 200 KW. Most of the fittings are twin tube lights. By the use of lighting voltage controller transformers, the voltage is reduced to 220V from 245V.