Three compressor overhauls in eighteen months traced to sub-micron aerosol carryover that the existing knock-out drum could never have removed.
- Measured carryover after commissioning
- 0.08 ppmw
- Compressor overhauls in 20 months since
- 0
- Installation inside planned shutdown
- 11 days
- Payback against deferred production
- 7 months
The challenge
The platform had suffered three unplanned compressor overhauls in eighteen months, each costing several weeks of deferred production. The operator suspected element quality. Sampling showed something else entirely: the existing vessel was a gravity knock-out drum being asked to remove aerosols below 3 µm — a duty no gravity separator can perform at any element quality.
How we approached it
- 01Isokinetic sampling at the compressor suction quantified actual carryover at 42 ppmw against a specification of 0.5 ppmw.
- 02Gas density was recalculated at true operating conditions, revealing the existing vessel was running at 2.3 times the critical Souders-Brown velocity.
- 03A two-stage coalescer was sized for the correct velocity, then modelled in CFD to confirm drainage back to the sump at minimum turndown.
- 04Deck loading and available footprint were verified against the platform structural drawings before fabrication released.
What we delivered
A SEPRA-C vertical coalescer in duplex 2205, sized to hold gas velocity at 0.6 times the Souders-Brown critical value across the full turndown range, with a two-stage element set and an instrumented liquid sump discharging to the closed drain header. Installed inside an eleven-day shutdown window.
The diagnosis was the valuable part. We had been replacing elements for a year and a half in a vessel that was never going to work. They told us that in the first meeting, with the numbers to back it.
Project facts
- Client
- Confidential — North Sea operator
- Industry
- Oil & Gas
- Location
- North Sea, United Kingdom
- Year
- 2025
Measured results
- 0.08 ppmw
- Measured carryover after commissioning
- 0
- Compressor overhauls in 20 months since
- 11 days
- Installation inside planned shutdown
- 7 months
- Payback against deferred production
What went in
Other programmes
Next step
Tell us what is in the stream.
Flow rate, contaminant, target rating, chemistry and available pressure. Six inputs, and our engineers return a staged design with the sizing basis attached — typically inside 48 hours.
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