LNG liquefaction, the real C3MR cascade

Natural gas precooled by a closed propane loop, then liquefied against a closed mixed-refrigerant loop in a multi-stream cryogenic exchanger.

Multi-stream enthalpy-based exchanger closure•Closed propane precool + mixed-refrigerant loops•Real C3MR cascade — the dominant world LNG process•Whole-train models at real capacity: 4.4 and 5.3 Mtpa•Mercury and mol-sieve guard beds, tank boil-off, driver derate•CO2 freeze-out limit, and CO2 compressed to 200 bar for reinjection

Natural gas

Propane precooler

C3 JT valve

C3 compressor

C3 condenser

Main cryogenic exchanger

MR compressor

MR aftercooler

LNG JT valve

Flash drum

LNG

Boil-off gas

The actual dark-mode canvas (simplified for this preview — the real flowsheet's exact refrigerant charges are set via tear specs): natural gas precooled by a closed propane loop, then liquefied to ~120 K against a closed mixed-refrigerant loop.

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Multi-stream exchanger, not a simple two-stream HX

Every hot and cold stream in the cryogenic bundle closes one shared enthalpy balance — the same free-stream closure a real APCI C3MR main exchanger runs, not a chain of two-stream heat exchangers.

\sum_i \dot n_{i,hot}\bigl(h_{i,hot,in} - h_{i,hot,out}\bigr) = \sum_j \dot n_{j,cold}\bigl(h_{j,cold,out} - h_{j,cold,in}\bigr)

h_{in} = h_{out} \quad \text{(isenthalpic JT throttle, every refrigerant letdown valve)}

T_{NG,\,out} \approx 120\text{ K}, \qquad T_{LNG} \approx 115\text{ K at storage pressure}

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Multi-stream LNG exchanger

Enthalpy-based free-stream closure across every hot/cold stream in one cryogenic bundle.

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Throttle valve

Isenthalpic Joule-Thomson expansion — the same relation cryogenic JT liquefaction relies on.

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Compressor

Polytropic compression to pipeline/process pressure.

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Heater / cooler

Duty- or outlet-condition-specified energy-balance stage.

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Flash drum

Single-stage vapor-liquid equilibrium split at a fixed temperature/pressure.

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Live plant integration

Stream MCHE approach temperatures and refrigerant compressor discharge from your train's OPC-UA server into this flowsheet's twin comparison — deviations from the solved exchanger duty are flagged automatically.

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✓Multi-stream enthalpy-based exchanger closure
✓Closed propane precool + mixed-refrigerant loops
✓The dominant real-world LNG process (APCI C3MR)

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LNG liquefaction, the real C3MR cascade

Multi-stream exchanger, not a simple two-stream HX

Unit ops shipped for this vertical

Try it yourself

Ready to modernize your LNG and natural gas simulations?

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