Upon entering MEG Feed stream to the Regeneration System, caustic is added to adjust the pH to approximately 10.5-11.5 and then is pre-heated via the Rich/Lean Glycol Exchanger. The pre-heated and pH adjusted Rich MEG feed stream then passes enters the Glycol Flash Drum.
In the Glycol Flash Drum, hydrocarbon impurities are separated and removed from the process. The Rich MEG exits the vessel and undergoes additional filtration through the Rich Glycol Filter and Charcoal Filter. The Rich Glycol Filter is capable of removing particles down to 10 micron size while the Charcoal Filter removes any dissolved hydrocarbons. The combination of these two filters will greatly reduce the chance of foaming from occurring in the Still Column. The salty Rich MEG Feed stream is then pre-heated via the Rich/Lean Glycol Exchanger.
The Still Column consists of a lower sump section and an upper packed column section. Liquid MEG solution is continuously pumped from the bottom of the sump section through the Regenerator Circulation Heater by the centrifugal Regenerator Circulation Pump.
Upon entering the Still Column, the hot MEG/water solution flashes, and the vapor phase, consisting mainly of water, flows upward into the packed section of the vessel while the residual liquid droplets of concentrated MEG fall into the liquid pool in the base of the column.
Water vapor rising from the sump area is distilled to a purity containing less than 150 MEG as it passes through the packing in the upper section of the Still Column.
A small flow of overhead condensate is refluxed to the top of the packing, under automatic flow control, to minimize MEG losses from the column.
The water vapor rising from the packing then exits the Still Column and flows to the External Reflux Condenser and then to the Reflux Drum. The Reflux Pump is used to reflux this overhead condensate and/or to transfer the water to the battery limit.