GAS COMPRESSORS | OPERATING EFFICIENCY |
Centrifugal | 70% |
Screw | 75% |
Reciprocating | 80% |
PUMPS | |
Centrifugal | 65% |
Reciprocating | 85% |
Rotary | 75% |
Typical Turndown Performance
LOAD | 100% | 75% | 50% | 40% |
Efficiency of Gas Turbine (3MW) | 28% | 26% | 21% | 18% |
Efficiency of Gas Recip Engine (2MW) | 38% | 36% | 32% | 30% |
Motor (300kW) | 94% | 94% | 93% | 92% |
Guideline for Driver Performance
Model | Type | Manufacturer | Power (HP) | Power (MW) | Efficiency (%) |
Saturn 20 | Open Cycle Turbine | Solar | 1,590 | 1.2 | 25 |
Centaur 40 |
Open Cycle Turbine | Solar | 4,700 | 3.5 | 28 | |
Centaur 50 | Open Cycle Turbine | Solar | 6,130 | 4.6 | 29 |
Taurus 60 | Open Cycle Turbine | Solar | 7,700 | 5.7 | 30 |
Taurus 70 | Open Cycle Turbine | Solar | 10,915 | 8.1 | 34 |
Mars 90 | Open Cycle Turbine | Solar | 13,220 | 9.9 | 32 |
Mars 100 | Open Cycle Turbine | Solar | 15,900 | 11.9 | 32 |
Titan 120 | Open Cycle Turbine | Solar | 20,500 | 15.3 | 35 |
Titan 250 | Open Cycle Turbine | Solar | 30,000 | 22.4 | 40 |
501-KC5 | Open Cycle Turbine | Rolls Royce / Siemens | 5,500 | 4.1 | 30 |
501-KC7 | Open Cycle Turbine | Rolls Royce / Siemens | 7,200 | 5.4 | 32 |
Avon 200 - 2648 | Open Cycle Turbine | Rolls Royce / Siemens | 21,923 | 16.3 | 31 |
Avon 200 - 2656 | Open Cycle Turbine | Rolls Royce / Siemens | 22,807 | 17 | 32 |
RB211 GT62 DLE | Open Cycle Turbine | Rolls Royce / Siemens | 41,084 | 30.6 | 39 |
Trent 60 | Open Cycle Turbine | Rolls Royce / Siemens | 72,679 | 54.2 | 44 |
Trent 60 - ISI | Open Cycle Turbine Water Injection | Rolls Royce / Siemens | 82,877 | 61.8 | 40 |
P9390GSI | Gas Engine Rich Burn | G.E Waukesha | 1,980 | 1.5 | 33 |
P48 GL | Gas Engine Lean Burn | G.E Waukesha | 1,065 | 0.8 | 37 |
AT 27 GL | Gas Engine Lean Burn | G.E Waukesha | 3,130 | 2.3 | 38 |
Small Electric Motor | Induction Motor | Various | 3 | 0.022 | 80 |
Large Electric Motor | Induction Motor | Various | > 400 | > 0.3 | 94 |
Large Electric Motor - VSD | Variable Speed Motor | Various | > 400 | > 0.3 | 91 |
Mathematics used to calculate gas compressor efficiency
First calculate the theoretical discharge temperature:
T2C = T1 * ((P2 / P1) ^ ((k - 1) / k))
Where:
T1 = Suction Temperature
P1 = Suction Pressure
P2 = Discharge Pressure
k = Ratio of Specific Heats
Next use theoretical discharge temperature and the actual measured discharge temperature to calculate the efficiency
isentropic efficiency = (T2C - T1) / (T2 - T1)
Where:
T2C = Calculated Discharge Temperature
T2 = Measured Discharge Temperature
T1 = Suction Temperature
ISENTROPIC & POLYTROPIC EFFICIENCY
ISENTROPIC (ADIABATIC) – No heat added or removed
POLYTROPIC – Heat leaves and enters
Empirical field experience has demonstrated that compression in positive displacement compressors (reciprocating and screw) closely follows a reversible adiabatic process (constant entropy). In dynamic compressors (centrifugal and axial) a Polytropic process is a more accurate method.
Air compressors efficiency is almost always stated on an isentropic basis. The Isentropic model has been used in the rotor.zone application primarily because it gives more reliable results in field tests.