Oil & Gas Operations challenge
Separation, compression, custody transfer, line pack and volume correction.
Oil & Gas · Professional Microtool
Compressor Power Calculator
Head · Gas power · Discharge temperature
Estimate gas power, adiabatic head and discharge temperature for a compression duty, and see what splitting the ratio across stages saves — in power and in heat.
Start from an example: 10 MMSCFD of natural gas, 20 to 70 bar a, two stages →
Full output
- —Gas power
- —Discharge temperature
- —Ratio per stage
- —Overall ratio
- —Adiabatic head
- —Mass flow
- —Specific power
Gas power against discharge pressure
The ratio enters through an exponent, so the curve flattens as pressure rises: the first few bar of a duty cost far more than the last few. That is also why raising suction pressure is usually worth more than any other change.
Keep it
Both carry the figures you entered, in the part of the address that is never sent to a server. Share only where that is appropriate. To keep a copy for a project file, print the page — it lays itself out as a document.
Need machine selection rather than a screening figure?
We can work from real gas composition, vendor curves and the full operating envelope, and integrate the result into your process and monitoring systems.
Calculation basis 5 steps · view the method →
Ratio per stage = (discharge ÷ suction) raised to 1/stages—Adiabatic head per stage = Z·R·T₁·k/(k−1)·[ratio^((k−1)/k) − 1], summed over the stages—Mass flow = standard flow × density at 0 °C and 101.325 kPa—Gas power = mass flow × head ÷ adiabatic efficiency—Discharge temperature = suction + ideal rise ÷ efficiency—
Assumptions & limitations Screening estimate for preliminary sizing and staging comparison · 7 assumptions →
This is a screening calculation using adiabatic head with perfect intercooling and constant gas properties. It is not a machine selection: it excludes real-gas behaviour beyond a single Z, interstage pressure drop and cooler approach, valve and recycle losses, mechanical and driver losses, side streams, and the manufacturer's actual performance map. Confirm with a process simulation and the vendor's curves before committing to a machine.
- Adiabatic (isentropic) head with a single efficiency; polytropic analysis will differ, more so at high ratio.
- Perfect intercooling: every stage is assumed to start at the suction temperature, and interstage pressure drop is ignored.
- The total ratio is split equally between stages, which is optimal only for identical stages.
- Gas properties — k, Z and molecular weight — are treated as constant across the whole machine.
- Standard flow is converted at 0 °C and 101.325 kPa; MMSCFD is taken at 60 °F and 14.696 psia and converted to that basis.
- Mechanical, bearing, seal and driver losses are excluded, as are recycle and anti-surge flows.
- Volumetric efficiency, valve losses and clearance effects of reciprocating machines are not modelled.
Worked examples
- 10 MMSCFD of natural gas, 20 to 70 bar a, two stages
Open with these figures → - The same duty squeezed into a single stage
Open with these figures →
About this tool
Compression cost is set by the pressure ratio, and not in proportion to it: the ratio enters through an exponent, so the second half of a duty is cheaper than the first, and splitting it across stages with intercooling is cheaper still. This tool makes that trade visible before anyone opens a vendor selection. Written for process, facilities and rotating-equipment engineers.
Go deeper
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