Hydrocarbon Water Wash Process

• The skimmed hydrocarbon stream from D-340 and the water from the bottom of T-340 go to M-350 (Water Wash Static Mixer).
• P-350A/B (Water Wash Circulation Pumps) circulate a water wash stream from the bottom of D-350 (Water Wash Settler).
• The water wash stream is heated in the shell side of E-350 (Water Wash Heater) by 100 psig steam on the tube side.
• The heated water wash stream joins the three-phase stream before being routed to and mixing in M-350.
• The resulting three-phase stream from M-350 goes to the bottom of T-350.
• In T-350, the vapor hydrocarbon separates from the liquid phases and rises through the packed bed.
• The vapor hydrocarbon is scrubbed with process water to remove any entrained caustic and/or aluminates and minimize liquid hydrocarbon.
• The scrubbed vapor hydrocarbon is routed to the shell side of E-351 (Water Wash Vapor Cooler) and cooled by cooling water on the tube side.
• Cooling in E-351 condenses the water in the vapor hydrocarbon prior to routing to D-360.
• E-351B (Water Wash Vapor Cooler) is used when E-351 is out of service for cleaning.
• The two liquid phases drop into D-350 and separate.
• Most of the water is recycled by P-350A/B to mix with the hydrocarbon again.
• Wastewater flows to D-353 before being drained to the Oily Water Sewer (OWS).
• Skimmed hydrocarbon is routed to the Debutenizer System.

Equipment Details

• P-350A/B (Water Wash Circulation Pumps) are single-stage centrifugal pumps driven by 25 HP 1750 RPM horizontally-mounted, induction electric motors
• P-350 A/B recirculate the water wash stream.
• Normally, one pump is in service and the other is on standby.
• E-350 (Water Wash Heater) is a shell and tube exchanger that heats circulating water on the shell side using 100 psig steam on the tube side.
• M-350 (Wash Water Static Mixer) has 2 carbon steel fixed elements.
• M-350 mixes the circulating process water with the hydrocarbon stream from D-340.
• T-350 (Water Wash Vapor Scrubber) is 2’D x 23’L.
• T-350 separates the vapor from the two liquid phases.
• The three-phase stream enters the side bottom of T-350.
• Fresh process water enters the side top of the scrubber.
• Overhead vapor exits from the top, and the two liquid phases exit from the bottom, going directly into D-350.
• E-351 (Water Wash Vapor Cooler) is a shell and tube exchanger that cools overhead vapor on the shell side with cooling water on the tube side.
• E-351 condenses water in the vapor before it's routed to D-360.
• E-351B (Water Wash Vapor Cooler) is a hairpin heat exchanger.
• E-351B cools the T-350 overhead vapor stream while E-351 is out of service.
• The process side of E-351B remains blinded and hydrocarbon-free when out of service to prevent contamination and thermal over-pressurization.
• D-350 (Water Wash Settler) is 7’D x 28’L and separates the two liquid phases into a recycled water stream and a skimmed hydrocarbon stream.
• A skim system removes any rag layer developed at the interface.
• The skim system has a skim pan that spans across the drum at 42-44% of the range of the interface float column
• The rag layer is periodically removed to D-353.
• D-353 (Wastewater Degassing Drum) is 3’D x 8’L.
• D-353 receives wastewater, separates the hydrocarbon vapor from the wastewater, and routes the hydrocarbon vapor to the LP Flare before the wastewater goes to the Oily Water Sewer.
• The liquid seal in D-353 must be maintained at all times.
• Failure to maintain the liquid seal will result in hydrocarbon vapor being released to the atmosphere.