Systems / Vacuum tower revamp and fuel gas
Unlock hidden capacity in existing assets.
Minox converts vacuum and fuel-gas deaerators to closed-loop nitrogen stripping. The tower shell stays, oxygen drops below 10 ppb, the scavenger goes to back-up, and the work is done during a turnaround.
100%
higher throughput, up to
<10 ppb
oxygen performance
0
oxygen scavenger required
Lower OPEX
and energy consumption
~7 months
fast, cost-effective retrofit
The revamp
Same tower. New way to remove oxygen
Most vacuum towers are limited by the vacuum system, not by the vessel. Take the vacuum out, and the same shell can treat more water to a lower oxygen spec.
[01]
Challenge
A vacuum tower needs two or three vacuum stages, ejectors and vacuum pumps with standby. Air leaks into the vacuum, so oxygen stalls at 50–80 ppb and a scavenger must be dosed all the time. Throughput is capped by the vacuum system.
[02]
Solution
Keep the shell and nozzles. Replace the internals with one packed bed and add the Minox closed nitrogen loop: an eductor, a heater and a catalytic deoxidiser. Nitrogen strips the oxygen, is cleaned, and goes round again.
[03]
Operation
The tower runs at slight positive pressure, so air stays out. The loop runs on pressure from the existing booster pumps. The scavenger stays connected, as back-up only.
Before and after
What stays and what you gain
Same tower, new way to remove oxygen. Before: two vacuum stages and a vacuum package. After: one packed bed and the Minox nitrogen loop.
Existing tower, nozzles and manways reused
Minimal hot work on the vessel
Below 10 ppb O₂, without chemicals
Vacuum pumps and ejectors decommissioned
Lower OPEX and power demand
Methanol or hydrogen as reactant
How the revamp works
Three steps inside the same shell
Conventional vacuum deaeration
Seawater trickles down through packed beds while vacuum pulls the dissolved oxygen out of the water.
- Two vacuum stages, each a separate section of the tower
- Vacuum package with ejector and vacuum pumps, plus standby units
- Oxygen scavenger chemical removes what the vacuum leaves behind
- Air leaking into the vacuum limits how low oxygen can go
Shown with two vacuum stages, the most common arrangement. Some towers use three.
Summary
Vacuum tower vs. Skyfri Minox
Lead time about 7 months. Installed during turnaround. Existing tower reused.
Two conversions
Vacuum towers and fuel-gas towers
Vacuum towers
Rebuilt to run at slight positive pressure with nitrogen stripping.
More water through the same tower, oxygen below 10 ppb, and the vacuum package taken out of service.
Fuel-gas towers
Gas treatment
→
Regenerated nitrogen (≥ 99.995 %) replaces fuel gas as stripping gas.
No flaring, no corrosion inhibitor, and the hazard of stripping with fuel gas is removed.
For the engineers
What the project team asks first
[01]
What pressure does the tower run at?
Normally 1–3 barg; anything from 0 to 4 barg is doable. Minox sets the optimum for each project, balancing the upstream lift pumps against the downstream boosters.
[02]
Which utilities are needed?
Nitrogen make-up, instrument air and a small methanol feed. Motive water comes from the existing booster pumps and equalises to tower pressure after the eductor.
[03]
Is there a nitrogen purity requirement?
No. Even instrument air can be used. The catalyst removes oxygen in the make-up gas; lower purity only adds a little methanol.
[04]
What does the study cover?
Internals configuration of the existing column, reuse of distributors and support plates, the methanol supply system, and power and utility tie-ins.
References
Revamps delivered
Start with a study
Tell us the tower, the capacity and the next turnaround
Send the tower data sheet or P&ID. We come back with a revamp concept, an oxygen guarantee and a lead time that fits your shutdown window.