Guidelines for Energy Auditing of Coal & Ash Handling Plants

1. Guidelines for Energy Auditing ofCoal & Ash Handling Plants Surender Kumar Deputy Director,NPTI

2. Coal Handling Plant – Energy Audit Methodology Major Equipments used are Crushers Conveyers Feeders Tipplers Stacker Reclaimers

3. Measurement and Observations to Be Made • Drive speed, belt speed ,roller condition, belt condition and belt loading with respect to design. • Power consumption of equipments load & unload condition • Loss of energy in the coal in stock yard due to spontaneous combustion • Equipments operations and throughput comparison with design conditions • Unit load of plant • Instrument used and frequency of measurement.

4. Measurement and Evaluation Measure the power input i.e. electrical parameters such as kW, kVA, Current, Voltage, power factor, for all drives for no load and load conditions -Coal throughput rate: Study track hopper management/ coal unloading. It is also desired to study time-motion study. Note the coal throughput using coal totalisers or other alternative methods.

5. Steps Involved • Data Collection • Observations and Analysis of • Drives Speed • Belt Tension • Roller Conditions • Belt Conditions • Belt Loading • Energy Conservation Measures

6. Steps Involved • Evaluation of specific energy consumption and capacity utilisation • Comparing design and PG values of • Overall CHP • Stage wise • Equipment wise - conveyor belts,paddle feeders, crushers, vibro feeders, belt feeders,wagon tippler, stacker, stacker,reclaimer ….

7. Data Collection • Design details of overall CHP • Capacity,specific power consumption etc • Process flow diagram • Track hoppers • Number , length , capacity, power, layout etc. • Paddle feeders • Number, capacity, travel, speed ,power • Wagon tippler • Number , type,capacity,maximum weight,time cycle, motor rating

8. Data Collection • Crushers • Number, type, capacity, coal size at inlet and outlet, motor rating, power consumption, number of vibrating feeders • Coal Design parameters and sizes • Belt Conveyors • Capacity , number, speed, width, motor rating power consumption • Stacker Reclaimer • Quantity, capacity, travel speed. Number of buckets and length of boom, motor rating • Other equipments • Vibrating feeders, dust suppression system pumps , belt feeders, dust extraction fans etc

9. Evaluation of Equipment Loading and Specific Energy Consumption • For direct bunkering , reclaiming and stacking use the table for power consumption and throughput Direct Bunker in Design capacity Average capacity tph Hrs operation

10. Key Specification parameters to be measured stream wise

11. Production and Operating Data

12. Coal Parameters

13. Major Performance Parameters • Calculation of Specific Energy Consumption Calculate kWH /MT for existing operations i.e. bunkering, stacking, and reclaiming both activity wise & equipment wise for last one year. Based on energy meter reading & coal receipt data, calculate month wise kWh / MT for last one year. Plot kWh/MT on Y-axis & months on X-axis.

14. Major Performance parameters • Coal Sample Analysis • Send 2-3 samples of coal taken from the belts feeding to the crushers for sieve analysis to determine extent of coal particles below 20 mm size and above 200 mm size or design size which ever is applicable. This analysis will help in optimising crusher operation • Lub Oil Inspection • Performance of Crushers If significant quantity of coal >20 mm size is observed on down side of crusher then it may led to substantial decrease in mill performance

15. Identification of Energy Conservation Possibilities • Performance improvement options: • Possibilities in Improving the throughput this is a major energy saving area which offers substantial saving at minimum investment. • Reducing the idling time. • Increasing the loading. • Modifications and changes in coal feeding circuits. • Need for automation and controls. • Identification of combination of various least power consuming equipments and recommending merit order operation. • Use of natural daylight through conveyor galleries and use of fire resistant translucent sheet.

16. Identification of Energy conservation possibilities • Maximum Mechanical Handling • : Minimum Bulldozing: • Sequence of coal handling operations like receipt, unloading, stacking and reclaiming and the selection of machinery is to be made in such a way that all the handling operations are accomplished without the use of semi mechanized means like bulldozers which are more energy intensive equipments. • However Principal of “FIRST IN FIRST OUT” is to be adopted for coal receipt & consumption and at any time coal need not to be stocked in yard for more than incubation period (duration between coal mined and getting self ignited)

17. Ash Handling Plant –Audit Methodology

18. The major energy consumers in ash handling plant are ash water pumps and ash slurry series pumps. • The contribution of wet ash handling plant in auxiliary power consumption varies between 1.5 to 2%. • Many systems have dry ash handling plant.

19. Major Objectives • Evaluation of ash water ratio • Analysis of higher consumption of water if any • Comparison of the ash water ratio with design value, P.G. Test value and previous energy audit values • Equipments performance

20. Instruments Required

21. Steps Involved • Data collection 1) line diagram 2) detailed specification pertaining to type,handling capacity,design ash %ash collection rates,fly ash and bottom ash extraction capacities,operating hours,design bulk densities

22. Steps Involved 3) PG test values/design values of coal parameters, ash generation, ash to water ratio, slurry velocities, no.of pumps involved. 4) Energy Consumption details 5) Water consumption details 6) Performance characteristics curves of all pumps, if in parallel then curve for parallel operation.

23. Operating parameters to be monitored • Water supply rate • Water velocity • Discharge • Head • Valve position • Temperature • Operating hours and schedule • Pressure drop in system • Pump/motor speed • Load of the plant • Discharge throttle valve position • Flow control frequency • % loading of pump on flow and head • % loading on motor

24. Performance Parameters for Pumps

25. Hydraulic power in KW = ( Q(m3/s)*total head (m)*density (kg/m3) ------------------------------------------------------ 1000 • Measurement of Electrical parameters and motor loading • Ash water and ash slurry water pressure and flow measurement.

26. Observations • Suction abstractions • Impeller pitting • Shaft alignment • Throttle control • Re-circulation • Clearances • Bearing condition • Inter-stage leakages

27. Motor Loading Parameters

28. Evaluation of ash to water ratio

30. While conducting the energy audit of the pumping, the following aspects need to be explored in detail for Optimisation / improving the ash to water ratios • Possibilities of reducing the operating hours of the AHP • Adequacy of pipe sizes • Improvement of pumping systems and drives. • Use of energy efficient pumps

31. Replacement of inefficient pumps • Use of high efficiency motors • High Performance Lubricants: The low temperature fluidity and high temperature stability of high performance lubricants can increase energy efficiency by reducing frictional losses. • Booster pump application

32. Thank you ..