Gas horsepower

Aeroderivative gas turbines eonsist of two basie eomponents an aireraft-derivative gas generator, and a free-power turbine. The gas generator serves as a produeer of gas energy or gas horsepower. The gas generator is derived... 

The gas horsepower is calculated using the companion head and efficiency. 

Figure 1. Gas horsepower for single-stage propane refrigeration system.

Figure 9. Gas horsepower for two-stage propylene refrigeration system.

Figure 17. Gas horsepower for three-stage ethane refrigeration system.

HP = Gas horsepower W = Flow, Ib/min Hpoiy = Polytropic head Had = Adiabatic head Ep = Polytropic efficiency Ea = Adiabatic efficiency... 

Power requirements and discharge temperatures are calculated using the same relationships as used with the other rotary compressors already discussed. The efficiency is. 80 for air service and pressure in the 30 psig range. The mechanical losses are higher than the other rotaries. The mechanical loss is variable and dependent on gas, lubrication, and other factors. For an estimate, use. 15 of the gas horsepower. This approxuna tion should be close enough for an estimate. 

Figure 11 -35. Gas horsepower for single-stage propylene refrigeration system. (Excerpted by special permission Mehra, Y. R. Chemical Engineering, Jan. 15,1979. McGraw-Hill, Inc., New York. All rights reserved.)...

This is approximately correct because the mechanical losses in the compressor are only about 1-3%. The head determined from Figure 12-67 can be used for the polytropic gas horsepower relation given previously. 

This compares with 1,339 bhp calculated by the gas horsepower relation. The values should agree exacdy, and the difference may lie in the reading of charts to determine the polytropic head. Using the bhp calculated with the adiabatic efficiency, e. ... 

To the gas horsepower is added bearing and oil seal losses. Use 50 hp in lieu of manufacturer s data for large machines. 

Example. A 50 ton two-stage propane refrigeration system has a 40°F evaporator temperature and a 120°F refrigerant condensing temperature. Find the gas horsepower requirement and condenser duty. 

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