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TIPS FOR ENERGY SAVING IN INDUSTRIAL EQUIPMENTS

By Russell Burns,2014-12-28 09:58
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TIPS FOR ENERGY SAVING IN INDUSTRIAL EQUIPMENTS

    Tips for Energy Saving in Industrial Equipments

    The industrial sector alone accounts for about 50% of the commercial energy. It uses both, the thermal and electrical energy in various equipments like boilers, compressors, furnaces, diesel generating engines, motors, pumps, refrigeration etc. Here are tips for energy saving through these equipments.

Electrical Energy General

    The industrial sector consumes about 33 per cent of the total electrical energy consumed in the country.

Tips for electrical energy saving:

     Improve power factor by installing capacitors to reduce KVA demand charges and

    also line losses within plant.

     Improvement of power factor from 0.85 to 0.96 will give 11.5% reduction of peak KVA

    and 21.6% reduction in peak losses. This corresponds to 14.5% reduction in average

    losses for a load factor of 0.8.

     Avoid repeated rewinding of motors. Observations show that rewound motors

    practically have an efficiency loss of upto 5%. This is mainly due to increase in no

    load losses. Hence use such rewound motors on low duty cycle applications only.

     Use of variable frequency drives, slip power recovery systems and fluid couplings for

    variable speed applications such as fans, pumps etc. helps in minimizing

    consumption.

Compressed air:

    Compressed air is used in almost all types of industries and accounts for a major share of Electricity used in some of the plants. It is utilized for a variety of end uses such as pneumatic tools and equipment, instrumentation, conveying, etc. and is preferred in Industries because of its convenience and safety. Normally, the compressed air factor is an overlooked area in most of the industries, though it is a costly source of power, about 7 to 10 times the cost of electricity. Given this economics, better maintenance practices and elimination of wastage would help in improving the performance of compressed air systems.

Tips for energy saving:

     Compressed air is very energy intensive. Only 5% of electrical energy is converted to

    useful energy. Use of compressed air for cleaning is rarely justified.

     Ensure low temperature of inlet air. Increase in inlet air temperature by 3?C increases

    power consumption by 1%.

     It should be examined whether air at lower pressure can be used in the process.

    Reduction in discharge pressure by 10% saves energy consumption upto 5%.

     A leakage from a ?” diameter hole from a compressed air line working at a pressure 2of 7kg/cm can drain almost Rs. 2500 per day.

     Air output of compressors per unit of electricity input must be measured at regular

    intervals. Efficiency of compressors tends to deteriorate with time.

Cooling towers:

    A cooling tower is a specialized heat exchanger in which two fluids (air and water) are brought into direct contact with each other to effect the transfer of heat. In a spray filled towers, this is accomplished by spraying a flowing mass of water into a rain - like pattern, through which an

    upward moving mass flow of cool air is induced by the action of a fan. There are two basic types of cooling towers, direct (or open) and indirect (or closed).

Tips for energy saving:

     Replacement of inefficient aluminum or fabricated steel fans by moulded FRP fans

    with aerofoil designs results in electricity savings in the range of 15-40%.

     A study on a typical 20 ft. diameter fan revealed that replacing wooden blade drift

    eliminators with newly developed cellular PVC drift eliminators reduces the drift

    losses from 0.01-0.02% with a fan power energy saving of 10%.

     Install automatic on-off switching of cooling tower fans and save upto 40% on

    electricity costs.

     Use of PVC fills in place of wooden bars results in a saving in pumping power of upto

    20%.

Electric motors:

     The electric motors are used to provide motive power to equipment such as compressors, pumps, blowers, etc. It is important that the industrial users define their need accurately to enable proper selection of a motor for a particular application. Of the total electricity consumed in the industrial sector, electric motors account for approximately 70%.

     The motors are classified under DC (direct current), AC (alternating current) synchronous, and AC induction (squirrel cage or wound rotor type) types. The AC induction is additionally distinguished as single or polyphase. Most of the power consumed by motors in the industry is accounted for by polyphase (three-phase) AC induction motors. Of the three-phase induction motors, the squirrel cage motor is most popularly used because of its relatively low capital and maintenance costs, and rugged design.

Tips for energy saving:

     The motors should be energy efficient.

     Convert delta to star connection for lightly loaded motors.

     Install soft start-cum-energy saver for lightly loaded motors.

     In case of centrifugal-blower pump, install variable voltage frequency (VVVF) drives for

    speed control of motors.

     Install multi speed motor.

     Optimize operating voltage level of motor for lightly loaded motors

     Replace eddy current controls with variable frequency drives for varying speed driven

    equipment?

     Provide interlock for electric motor to avoid idle running

     Replace motor generating sets with thyristor drives.

     Avoid frequent rewinding of motors. Greater the number of rewind, lesser the efficiency.

     Carry out preventive maintenance and condition monitoring schedule regularly.

Advantages of Energy Efficient Motors

     Reduced operating costs

     Less heat losses

     Extended winding lifespan

     Extended lubricating grease service life

     Lower noise levels than other motors

     Reduced energy costs. The higher purchase price investment pays off.

     Reduce emission of CO2 and NOx greenhouse gasses from power stations for positive

    environmental effect.

Lighting:

    A lumen is the measurement of light output from a lamp, often called a tube or a bulb. All lamps are rated in lumens. For example, a 100-W incandescent lamp produces about 1750 lumens. The distribution of light on a horizontal surface is called its illumination, which is measured in foot-candles or lux. A foot-candle of illumination is a lumen of light distributed over 2one-square-foot (0.09 m) area. Another lighting term is efficacy, which is the ratio of light output from a lamp to the electric power it consumes and is measured in LPW (lumens per watt).

    Lighting uses can be divided into three categories: ambient, task, and accent. Ambient lighting provides security and safety, as well as general illumination for performing daily activities. The goal of task lighting is to provide enough illumination so that tasks can be completed accurately. The idea here is not to illuminate the entire area. Accent lighting illuminates walls to blend more closely with naturally bright areas like ceilings and windows.

Tips for energy saving:

     Use of electronic ballast in place of conventional choke saves energy upto 20%.

     Use of CFL lamp in place of GLS lamp can save energy upto 70%.

     Clean the lamps and fixtures regularly. Illumination levels fall by 20-30% due to collection

    of dust.

     Use of 36W tube light instead of 40 W tube light saves electricity by 8 to 10%.

     Use of sodium vapour lamps for area lighting in place of mercury vapour lamps saves

    electricity upto 40%.

Pumps:

    Most of the industrial processes in and out of plants involve transportation of fluids and the pump is the only mechanical means available to facilitate this transportation. Work has to be done by a prime mover in order to enable the pump to discharge its functions, because the pump is incapable of transporting the fluid on its own. The prime mover can either be an electric motor, a diesel engine, on a steam/gas turbine. All prime movers consume energy, either in the form of electric power or precious petroleum products like diesel, oil or gas, to impart working capacity to the pump.

Tips for energy saving:

     Select a pump of the right capacity in accordance with the requirement. Improper

    selection of pumps can lead to large wastage of energy. A pump with 85% efficiency at

    rated flow may have only 65% efficiency at half the flow.

     Matching of the motor with the appropriate-sized pump.

     Use of throttling valves instead of variable speed drives to change flow of fluids is a

    wasteful practice. Throttling can cause wastage of power to the tune of 50 to 60%.

     It is advisable to use a number of pumps in series and parallel to cope with variations in

    operating conditions by switching on or off pumps rather than running one large pump

    with partial load.

     Void valves in the pipe line throttle wastes energy. A positive displacement pump with

    variable speed drive is recommended.

     Proper installation of the pump system, including shaft alignment, coupling of motor and

    pump is a must. Drive transmission between pumps and motors is very important. Loose

    belts can cause energy loss upto 15-20%.

     Modern synthetic flat belts in place of conventional V-belts can save 5% to 10% of energy.

     Properly organized maintenance is very important. Efficiency of worn out pumps can drop

    by 10-15% unless maintained properly.

Refrigeration and Air-Conditioning:

    Refrigeration is the process of removing heat at a low temperature level and rejecting it at a relatively higher temperature level. Refrigeration is accomplished by various methods, such as the vapour compression system, absorption system, and steam jet refrigeration cycle. The most commonly used systems are the vapour compression and absorption systems. Further, even out of above two, the vapour compression system is more widely used.

    The items required for the make-up of a complete refrigeration and air-conditioning system are refrigerating equipment, fans, pumps, cooling towers, filters, air-handling units, and ducting. Depending upon the process, all or some of the items mentioned may be required.

Tips for energy saving: