As gas-liquid mixture enters the screw bore, the twin screws convey the mixed stream axially — the sealed screw cavities progressively compress the gas phase as discharge pressure builds along the screw length. Liquid film on screw flanks and bore walls provides sealing between axial stages — gas compression is cushioned by the liquid film rather than dry compression. At 95% GVF (5% liquid), the liquid forms a thin continuous film that seals the running clearance — the pump continues to deliver the gas-dominant mixture to the required discharge pressure. Liquid flushing of screw flanks is used at very high GVF (>95%) to maintain sealing film.
Challenges
GVF Transition Shock (Liquid Slug After High-GVF Operation)
Sudden liquid slug at high GVF causes hydraulic shock — instantaneous torque spike and potential screw contact.
Dry Running at 100% GVF (No Liquid Film for Lubrication or Sealing)
At 100% gas, no liquid film is present — screws must be lubricated and sealed by external flush fluid.
Temperature Rise from Adiabatic Gas Compression at High GVF
Gas compression generates significant heat at high GVF and high pressure ratio — product and pump temperature can exceed limits.
Pressure Pulsation at Low-GVF (Gas Pocket Collapse on Liquid Fill):
Gas bubbles collapsing at discharge create pressure spikes — cavitation-like damage on screw surfaces.
Seal Failure from Alternating Gas-Liquid Exposure (Seal Face Liftoff on Gas Phase)
Mechanical seal faces lift off on dry-gas phase then slam on liquid phase — cyclic loading causes premature face failure.
Solutions
- Slug Detection (Differential Pressure Rate-of-Change Sensor) + VFD Deceleration: Rapid dP/dt increase triggers VFD deceleration — absorbs liquid slug energy before screw contact.
- Liquid Injection Flush at Screw Bore (5–10% of Flow as Seal/Lube Fluid): Dedicated liquid injection at suction maintains minimum film at any GVF including 100% — prevents dry running.
- Inter-Stage Cooling via Jacketed Casing (Water or Process Fluid Coolant): Jacket cooling at each screw stage limits bulk gas temperature rise — keeps casing and product within limits.
- Suction-Side Degasser (Hydrocyclone) Removes Free Gas Before Pump at >95% GVF: Degasser separates excessive gas before pump — limits pump inlet GVF to <95% for stable operation.
- Gas-Loaded Double Mechanical Seal (API 682 Plan 52, N₂ Buffer Gas): N₂ buffer maintains constant face pressure regardless of process GVF — eliminates liftoff on gas phase.
Applications
- Oil & Gas (Upstream): Wellhead multiphase boosting — transfers well stream direct to pipeline without separation.
- Oil & Gas (Midstream): Multiphase pipeline booster stations — maintains flow to processing facility from remote wells.
- Petrochemical: Flare gas recovery pumping — captures vent and relief gases for recompression.
- Chemical: Process vent handling, two-phase reactor discharge pumping — mixed gas-liquid stream conveyance.
- Power & Utilities: Condensate-gas mixture transfer from steam traps and condensers to recovery headers.
Models & Capacities
Type 1D — Multiphase / Gas-Liquid Twin Screw Pump: Models & Capacities | ||||||||||||
Model | Scale | Total Inlet Flow [m³/h] | Screw Ø [mm] | Max GVF [%] | Speed [RPM] | Max Suction Press. [bar] | Max Discharge Press. [bar] | Max Liquid Viscosity [cP] | Liquid Flush Required | Motor [kW] | L×W×H [mm] |  |
TSP-MP-063 | Pilot | 1–20 | Ø63 | 97 | 200–1,800 VFD | 10 | 30 | 10,000 | Yes (>80% GVF) | 2.2 | 850×380×450 |  |
TSP-MP-100 | Pilot | 5–60 | Ø100 | 97 | 200–1,800 VFD | 20 | 40 | 10,000 | Yes (>80% GVF) | 4.0 | 1,050×450×540 |  |
TSP-MP-125 | Production | 10–120 | Ø125 | 97 | 200–1,600 VFD | 30 | 50 | 10,000 | Yes (>80% GVF) | 7.5 | 1,260×540×650 |  |
TSP-MP-160 | Production | 20–250 | Ø160 | 97 | 200–1,450 VFD | 40 | 60 | 10,000 | Yes (>80% GVF) | 11 | 1,520×650×780 |  |
TSP-MP-200 | Production | 50–500 | Ø200 | 97 | 200–1,200 VFD | 50 | 70 | 10,000 | Yes (>80% GVF) | 18.5 | 1,820×780×940 |  |
TSP-MP-250 | Production | 100–1,000 | Ø250 | 97 | 150–1,000 VFD | 60 | 80 | 10,000 | Yes (>80% GVF) | 30 | 2,200×940×1,130 |  |
TSP-MP-315 | Large Prod | 200–2,000 | Ø315 | 97 | 120–800 VFD | 70 | 90 | 10,000 | Yes (>80% GVF) | 45 | 2,650×1,130×1,360 |  |
TSP-MP-400 | Large Prod | 400–4,000 | Ø400 | 97 | 100–650 VFD | 80 | 100 | 10,000 | Yes (>80% GVF) | 75 | 3,200×1,360×1,640 |  |
TSP-MP-500 | Large Prod | 700–7,000 | Ø500 | 97 | 80–500 VFD | 80 | 100 | 10,000 | Yes (>80% GVF) | 132 | 3,850×1,630×1,970 |  |