In the pretreatment stage, the rich MEG—containing some dissolved gas and hydrocarbon liquids—is heated and passed through a three-phase separator vessel. The gas is flashed to flare and liquid hydrocarbons are sent to the condensate recovery system. The treated MEG is sent either to storage or the downstream process.
MEG regeneration is conducted in a reflux distillation column. For a slipstream process, the column operates off the low-pressure flare backpressure and is provided with a pump-around heating loop. For a full-stream system, the distillation column operates under vacuum conditions.
The lean MEG produced at the bottom of the column is pumped to storage for reuse. For the slipstream service, a portion of the lean MEG is sent for reclamation. The vaporized water passes overhead where it is condensed and collected in the reflux drum. A portion of the water is returned to the distillation column to provide reflux while the remainder is routed to water treatment. Residual hydrocarbons in the system are generally associated with this produced water stream, and we provide a wide range of water treatment systems capable of meeting local environmental legislation for discharge.
Flash separation (reclaimer)
In the flash separator, the rich MEG stream (full-stream reclamation) or lean MEG stream (slipstream reclamation), consisting of water and MEG with dissolved salts, is brought into contact with a hot recycled stream of concentrated MEG. The flash separator operates under vacuum conditions to maintain process temperatures below the degradation temperature of MEG. The feed MEG and water are vaporized and exit through the top of the flash separator. These vapors either pass to the MEG distillation column for regeneration (full-stream service) or are condensed and sent to lean MEG storage (slipstream service). The monovalent salt components, primarily sodium chloride, precipitate in the flash separator. They fall via gravity through a column of brine and are collected in the brine-filled salt tank.