Oil & Gas Operations challenge
Separation, compression, custody transfer, line pack and volume correction.
Oil & Gas · Interactive Engineering Model
Compressor Power Calculator
Head · Gas power · Discharge temperature
Change the duty and the number of stages and see what each costs — gas power, adiabatic head and discharge temperature, and what splitting the ratio across stages saves in both power and heat.
Volumetric flow at standard or normal conditions, as gas is contracted. Actual volume at suction is much smaller.
Absolute pressure at the compressor inlet, not gauge.
Absolute pressure required at the outlet. The ratio to suction is what sets the power.
Compression stages with intercooling between them. Splitting the ratio cuts both power and discharge temperature.
Start from an example: 10 MMSCFD of natural gas, 20 to 70 bar a, two stages →
Advanced parameters5
- —Gas power
- —Gas power
- —Discharge temperature
- —Ratio per stage
- —Overall ratio
- —Adiabatic head
- —Mass flow
- —Specific power
Move a parameter and the train answers: the pressure each stage adds, how hot the gas gets doing it, and what the shaft has to pay.
The link carries the figures you entered, in the part of the address that is never sent to a server.
Change one assumption at a time. The model updates from the same calculation used for the reported result.
Try this
Keep the same suction and discharge conditions. Compare one-stage compression with multiple stages and watch both power and discharge temperature.
How the model works
- The ratioCompression is paid for in pressure ratio, not pressure difference. The ratio enters the work through an exponent, which is why a duty that starts higher costs so much less than one that ends lower.
- The stagesThe train splits the ratio equally between its stages. Each stage does the same work, and the pressure climbs in equal steps rather than in one leap.
- The heatSqueezing gas heats it. Between stages it is cooled back to the suction temperature, so the next stage starts cold — that is what keeps the discharge temperature off the metal's limit, and it lowers the work as well.
- The shaftThe shaft pays for the gas and for the machine: the work the gas needs, plus everything the efficiency wastes. The waste does not disappear — it arrives as heat in the gas leaving.
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 →
What this model reveals
Compression is paid for in pressure ratio, not pressure difference, and the ratio enters the work through an exponent. Splitting that ratio across stages, with the gas cooled between them, lowers both the work and the temperature the metal sees. The model shows the stages, the heat each one adds, the cooling that takes it back out, and what the same duty would cost in a single stage.
Go deeper
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