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Eleven stages · three products
From raw well gas to three finished products. Follow the train from inlet separation to export compression, drop into the NGL branch, or trace any product back to the wellhead.
Stage 01 · First, take out what isn’t gas
Removes entrained liquids and solids from the rich inlet gas
Rich gas arriving from DPS & BBS may still carry entrained liquids, condensate, and trace solids. The inlet separator is a vertical two-phase vessel that slows the stream down so gravity can pull these liquids and solids out, sending a clean gas stream onward to compression. Stable separation here protects every downstream unit from liquid carryover and fouling.
Stage 02 · Bringing the field up to plant pressure
Boosts feed gas to plant operating pressure
The inlet compressors raise the feed gas to the plant’s operating pressure, with interstage coolers and scrubbers knocking out the liquids that condense as the gas is compressed and cooled. A steady discharge pressure gives the treating units a constant, predictable feed.
Stage 03 · A few micrograms would wreck the cold end
Protects downstream equipment — particularly the aluminium internals of exchangers and columns — from mercury attack
Trace mercury occurs naturally in many gas fields, and even a few micrograms per cubic metre will attack the brazed-aluminium heat exchangers of the cryogenic unit, as well as the aluminium trays and packing in the columns, causing amalgam corrosion and embrittlement. The gas flows through fixed beds of sulphur-impregnated adsorbent, where mercury is captured as stable mercuric sulphide. Placing the unit early in the train protects every exchanger and column downstream.
Stage 04 · Taking the sour out, one bed at a time
Removes H₂S using solid beds in a lead-lag configuration
Hydrogen sulphide (H₂S) makes gas corrosive, toxic, and unsaleable if left untreated. The gas passes through fixed beds of solid adsorbent in a lead-lag configuration: the lead vessel removes the bulk of the H₂S, while the lag vessel safeguards downstream equipment and ensures the sweetened gas meets the sales gas specification of maximum 5 ppmv H₂S. Once a bed’s media is fully spent, it is replaced.
Stage 05 · Bone dry, or the cold end turns to ice
Dries the gas so no ice or hydrates can form in the cold section
Any water vapour left in the sweetened gas would form ice and gas hydrates the moment temperatures drop in the cryogenic section, plugging exchangers and valves. The gas therefore passes through twin molecular-sieve adsorber beds: one dries the gas while the other regenerates. When a bed’s media becomes saturated, a portion of dry gas is heated and flowed from bottom to top to drive off the trapped water; toward the end of the cycle, the heater is bypassed so the bed cools back to operating temperature before switching back into service.
Stage 06 · Minus 110 °C, and the liquids appear
Chills gas to ≈ −110 °C to condense LPG & NGL
The heart of LPG and NGL recovery. Dry, sweet gas is cooled to roughly −110 °C through a chiller, exchangers, and a turbo-expander, which extracts work from the gas while dropping its temperature to maximise liquid recovery.
Stage 07 · The final split: gas up, liquids down
Separates lean gas from C3+ liquid in a packed column
With the gas now chilled, it’s ready for its final split. The cooled gas enters the de-ethanizer, a packed column that separates methane and ethane (lean gas) overhead from the heavier C3+ liquid, which flows to the debutanizer for separation into LPG and NGL.
Stage 08 · Back to pressure, and out to the grid
Restores lean gas to pipeline pressure for export and plant fuel/utilities use
The lean residue gas leaving the cryogenic unit is at low pressure after expansion. The export compressors restore it to sales-pipeline pressure, with after-coolers bringing it back to specification temperature. A regulated slipstream is drawn off as fuel gas to supply the gas plant, power plant, DPS, and BBS, and the remainder passes through the Gas LACT unit for custody transfer metering into the sales-gas pipeline.
Stage 09 · One clean cut makes two products
Separates C3+ liquid into LPG and NGL
The C3+ liquid stream from the de-ethanizer is a mix of propane, butane, and heavier gasoline-range liquids. The debutanizer is a distillation column that makes one clean cut: propane and butane vapours rise overhead, are condensed and become LPG, while the pentane-plus C5+ bottoms leave as a stabilised natural gas liquid (NGL) suitable for blending into crude oil.
Stage 10 · Held under its own pressure, ready for the trucks
Pressurised bullet tanks buffering LPG for dispatch
LPG is held as a liquid under its own vapour pressure in pressurised bullet tanks. Storage buffers the difference between steady production and batch offtake, and each tank carries relief, deluge, and gas-detection systems. Product is loaded onto road tankers for delivery to market, with each shipment weighed on a weighbridge to confirm the dispatched quantity.
Stage 11 · Blended into crude, and worth more for it
Holds stabilised NGL for export to DPS to enhance crude quality
Stabilised pentane-plus liquids are held in low-pressure storage before export to DPS, where they are pumped into the crude-oil stream to enhance its API gravity, adding volume and value to the blend.
Tracing
Lean, dry, sweet natural gas metered into the sales-gas pipeline.
To sales gas pipeline
Its route through the plant
Tracing
Liquefied petroleum gas — a propane–butane mix — dispatched by road tanker.
To LPG road tankers
Its route through the plant
Tracing
Stabilised natural-gas liquids blended into the crude-oil export stream.
Blended with crude to enhance API
Its route through the plant
End of the train
One rich gas stream arrives from the fields. Eleven stages later it leaves as three finished products, each to its own destination.
To sales gas pipeline
Lean, dry, sweet natural gas metered into the sales-gas pipeline.
To LPG road tankers
Liquefied petroleum gas — a propane–butane mix — dispatched by road tanker.
Blended with crude to enhance API
Stabilised natural-gas liquids blended into the crude-oil export stream.
