Cryogenic fractionation columns that split methane-rich residue gas overhead from ethane-plus NGL bottoms — engineered around turboexpander-driven refrigeration for maximum hydrocarbon recovery.
A demethanizer tower is the fractionation column at the heart of NGL recovery — it takes chilled, dehydrated feed gas and separates it by true distillation into a methane-rich residue gas overhead and an ethane-plus liquid (NGL) bottoms product. What makes it different from a conventional distillation column is the refrigeration source: rather than a fired reboiler alone, the feed is typically cooled by near-isentropic expansion across a turboexpander, dropping temperatures to −100°F to −150°F while extracting shaft work used to recompress the residue gas.
Fintelius engineers every demethanizer around the actual recovery target — feed composition, desired ethane recovery percentage, and available refrigeration — then fabricates the column, feed arrangement, and side-reboiler system to hit it, whether the unit ships as a standalone column or a fully modularized, skid-mounted plant.
Every demethanizer follows the same disciplined path through design and fabrication.
Feed composition, volume, pressure, and target ethane/NGL recovery rate set the process cycle and column sizing basis.
ISS, GSP, or RSV cycle is selected, defining how turboexpander duty, feed splits, and reflux are arranged around the column.
Shell is rolled and fitted with cryogenic sieve or valve trays, feed nozzles, and side-reboiler connections.
Welds are radiographed and ultrasonically tested; materials and welds are qualified for cryogenic service temperatures.
The complete tower is hydrostatically tested, insulated, and prepared for shipment as a standalone column or modular skid.
Pre-cooled feed splits, with turboexpander-cooled feed routed to the column top — a straightforward configuration for moderate recovery targets.
Split flow directs part of the feed to a top condenser and part to the expander, typically achieving 85–92% C2 recovery.
Adds a residue-gas recycle compressor to boost reflux, reaching the highest recovery range at roughly 92–98% C2.
Extreme temperature spread across the column drives design decisions a warm-service tower never has to make.
Typically 20–30 actual trays in a 10–15 m column, engineered for reliable operation at cryogenic temperatures with roughly 65% typical tray efficiency.
Column top and feed nozzles engineered around the near-isentropic expansion duty that supplies the tower's primary refrigeration.
Two or three side reboilers integrated with the warm-end feed-gas chiller, rather than a single bottom reboiler, to minimize cold-end exergy loss.
A dedicated overhead condenser generates reflux liquid for GSP and similar configurations requiring enhanced separation.
C1/C2 relative volatility varies from roughly 5.5 at the cold top to 3.0 at the warm bottom — tray count and feed point are set against this profile.
Shell, tray, and nozzle materials qualified for the column's coldest operating temperature, typically down to −150°F.
Rolled shell and formed heads engineered for the column's diameter, height, and cryogenic-service wall thickness.
Sieve or valve trays fitted and leveled to the process design across the full tray count.
Feed, reflux, overhead, bottoms, and multiple side-reboiler nozzles with reinforcement pads.
Skirt and anchor bolt design engineered for combined dead load, wind, seismic, and thermal contraction at cryogenic temperature.
Multi-layer insulation packages minimizing heat ingress and preventing external icing across the cold section of the tower.
Stress-relief heat treatment for thick-walled sections per code requirements.
Weld integrity verification across all shell, tray-support, and nozzle welds before hydrostatic test.
Full-vessel pressure testing to design specification prior to dispatch.
Complete modularized plant packages integrating the column with turboexpander, compression, and heat-exchange equipment for wellsite or midstream deployment.
Primary NGL recovery from wellhead and gathered gas ahead of residue-gas sales-line delivery.
Central processing plants fractionating gathered gas into methane residue and NGL products for downstream fractionation.
Skid-mounted units delivering NGL recovery capability directly at the wellsite where full plant infrastructure isn't justified.
Ethane and heavier NGL recovery supplying feedstock to downstream petrochemical cracking operations.
Reducing downstream compression duty by extracting recoverable liquids before residue gas reaches sales compression.
Upgrading existing lean-oil or JT-valve recovery systems to true cryogenic fractionation for higher recovery and lower fuel consumption.