4. Pump Efficiency: Where, Hydraulic power, P h (kW) = Q x (h d - h s ) x x g / 1000 Q = Volume flow rate (m 3 /s), = density of the fluid (kg/m 3 ), g = acceleration due to gravity (m/s 2 ), (h d - h s ) = Total head in metres
5. As run Trials for Determination of Pump Efficiency To determine the pump efficiency, three key parameters are required: Flow, Head and Power . Of these, flow measurement is the most crucial parameter as normally accurate online flow meters are hardly available, in majority of pumping systems. The following methods can be adopted to assess the flow depending on the availability and site conditions.
9. 3-Tank filling method: In open flow systems such as water getting pumped to an overhead tank or a sump, the flow can be measured by noting the difference in tank levels for a specified period during which the outlet flow from the tank is stopped. The internal tank dimensions should be preferable taken from the design drawings, in the absence of which direct measurements may be resorted to.
10. 4-Installation of an on-line flow meter: If the application to be measured is going to be critical and periodic then the best option would be to install an on-line flow meter which can get rid of the major problems encountered with other types.
12. ILLUSTRATIVE EXAMPLE: BOILER FEED PUMP Sl. No. Item Ref. Units Design Unit # 1 Unit # 2 Unit # 3 Unit # 4 BFP # 1 BFP # 2 BFP # 3 BFP # 4 1 Unit Load MW 60 52 56 55 60.1 2 Grid frequency Hz 50 49.39 49.75 51.34 49.47 3 BFP flow TPH 308 225 235 255 246 4 Suc. Pressure Kg/Cm 2 5.5 6.2 6.8 5.8 5 Disch. Pressure Kg/Cm 2 148.2 136.7 135 127.0 6 Boiler Drum Pr. Kg/Cm 2 100 81 85 81 89 7 Total head Kg/Cm 2 112.5 142.7 130.5 128.2 121 8 Suction temp. O C 175 151 158.4 157 155 9 Liquid density Kg/m 3 0.9047 0.91 0.905 0.905 0.91 10 BFP Amps A 270 263.60 247.20 253.60 244.80 11 BFP motor power KW 1305.5 1268.88 1211.99 1225.77 1214.10 12 Liquid KW KW 1043.67 874.93 835.48 890.83 812.46 13 Combined Eff.* % 73.60 68.95 68.93 72.67 66.9 14 % Load on motor % 97.2 92.8 93.9 93.0 15 % Load on flow % 73.05 76.30 82.79 79.87 16 % Load on head % 126.84 115.97 113.96 107.73 17 SEC kWh/T 4.2386 5.6395 5.1574 4.8070 4.9354
13. ILLUSTRATIVE EXAMPLE:CEP Performance & Valve Loss S. No. Item Reference Units Rated Unit-1 Unit-2 Unit-3 1. Unit load MW 200 197 211 196 2. Frequency Hz 50 49.5 49.74 49.53 3. CEP flow M 3 /hr 610 510 5.17 525 4. Suction pressure MWC - 3.1 3.3 3.8 5. Discharge pressure MWC - 215.3 215.3 210.3 6. Total head developed MWC 190 211.7 211.7 206.5 7. Density @ 40 0 C Kg/m 3 0.9922 0.9922 0.9922 0.9922 8. Liquid power of pump kW 313.36 247.67 295.92 293.11 9. Power input to motor kW 433.66 414.04 444.15 450.50 10. Motor efficiency % 92.7 92.7 92.7 92.7 11. System efficiency (pump & motor) % 72.3 66.36 66.6 65.1 12. CEP efficiency (pump) % 78 71.56 71.80 70.19
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15. Fans – Purpose of the As run performance Tests : The purpose of such tests is to determine, under actual operating conditions, the volume flow rate, the power input and the total pressure rise across the fan. These test results will provide actual value for the flow resistance of the air duct system, which can be compared with the value specified by supplier.
16. Performance Terms and Definitions Fan Efficiency: The air power static divided by impeller power Static Pressure: The absolute pressure at a point minus the reference atmospheric pressure. Dynamic Pressure: The rise in static pressure which occurs when air moving with specified velocity at a point is bought to rest without loss of mechanical energy. It is also known as velocity pressure. Total Pressure : The sum of static pressures and dynamic pressures at a point. Fan Shaft Power: The mechanical power supplied to the fan shaft Motor Input Power: The electrical power supplied to the terminals of an electric motor drive
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