LNG BOG Compressor - Shaft Power
Adiabatic shaft-power estimate for a boil-off gas (BOG) compressor handling methane from atmospheric tank vapour to the DF-engine supply pressure.
Adiabatic discharge temperature
232.0K
Adiabatic gas power
126.4kW
Shaft power
168.5kW
Formula, assumptions, and limits
k≈1.31 and cp≈2.22 kJ/kg·K for methane at cryogenic suction. Re-heaters often add 50–60 K to suction to improve compressor life. For two-stage machines apply formula per stage with inter-cooling.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| BOG mass flow | kg/s | tank BOR × volume × density | |
| Specific heat at constant pressure | kJ/kg·K | NIST REFPROP | |
| Suction temperature | K | suction RTD | |
| Isentropic exponent | - | NIST (methane) | |
| Adiabatic efficiency | - | machine data sheet |