-Regeneration Unit
Rich (and wet) Glycol is flashed to 65 psig through LCV, and is preheated through the shell side of the Glycol Overhead Condenser. Then, it is further preheated in the Cold Glycol/Glycol Exchanger to 200F before entering Glycol Flash Drum for phase separation. In the Flash Drum, flashed gas is vented to LP flare header at 45 psig backpressure. Entrained liquid hydrocarbons is skimmed into a bucket, and later drained to Closed Drain Header. Separated Rich Glycol flows further to the Reboiler via the filter sets.
Rich glycol passes through Wet Glycol Filter to remove 99% of particle 5 microns and larger. Each filter is designed for 100% flowrate (One Duty, One Stand-by). Then, it flows to Glycol Carbon Filter to remove degradation products and contaminants. Note that, carbon filter is designed for 25% of total glycol flow only, other 75% is by-passed. Then, it flows under Glycol Flash Drum level control to the Hot Glycol/Glycol exchanger and then into Glycol Still Column at approx. 325F.
Glycol Still Column is filled with Random Packing and mounted on top of the Reboiler . Hot Rich Glycol flows down the column against rising vapors from the Reboiler and becomes progressively leaner in Water (i.e. drier). The vapor, on the other hands, are cooled by the Rich Glycol and by the Glycol Overhead Condenser above, become partially condensed, and form a reflux stream in the Still Column. Non-condensed vapor (consist mainly water steam and BTEX vapor) left at the top and is routed to the BTEX Recovery unit.The Glycol Reboiler is heated by a Hot Oil Exchanger (U-tube bundle) and produces TEG of about 99.5% weight purity at 395ºF. In order to achieve this purity and keep Glycol Circulation rate low, Stripping Column containing Random Packing is provided.
The Lean TEG, leaving the Reboiler via an Overflow Nozzle so that the hot oil bundle is adequately submerged at all time, is contacted with Stripping Gas in the Stripping Column . The stripping Gas is supplied from the Fuel Gas Distribution System.
From bottom of Stripping Column , Lean TEG is cooled in Hot Glycol/Glycol exchanger & Cold Glycol/Glycol Exchanger to 198F and routed to the Glycol Surge Tank that acts as a reservoir and allows continuous pumping. Lean TEG is pumped by Glycol Circulation Pump up to the top of the Contactor via Glycol Cooler. Flow control of Lean TEG is provided by a spill back line and control valve downstream of the Circulation Pumps.
The Glycol cooler ensures the final Lean TEG cooling so that the glycol temperature is approx. 10F higher than Gas temperature. This prevents hydrocarbons in the gas to condense and cause foaming.
TEA/MEA amine is used for pH control and is injected to the system via Glycol Conditioning Pump (P-1275). This chemical reacts with acid components that are generated by Glycol degradation.