Complete treatment of wet, sour, condensable hydrocarbon gases is now available in a single process unit.
Ifpexol, developed by the Institut Francais du Petrole with backing from the EC Thermie project, incorporates the freeze-point depression qualities of a methanol-based solvent. The single-solvent process allows the three types of gases to be removed efficiently in conventional cold processing equipment to any required gas specifications.
The system comprises two steps, IFPEX-1 and IFPEX-2. In the former step, a feed gas slipstream flows up a column in counter-current contact with a descending water-laden methanol stream from the cold separator. Solvent is stripped out of the water by this feed gas. At the same time, gas exiting the column contains sufficient solvent to prevent formation of hydrates during subsequent pipeline transport and cold processing.
Hydrocarbons, methanol and water condensed during the cold process are separated in the cold separator. The cold process restrains the temperature of the gas in accordance with the specified water/condensable hydrocarbon dewpoint.
The already-cold sour gas then passes up a second column where it comes into contact with a chilled solvent stream descending. Acid gases are absorbed in the methanol stream, allowing the exiting gas to meet sweet gas specifications. A conventional regeneration process desorbs the acid gas from the methanol which is recovered for recycling to the IFPEX-2 column.
Should any water accumulate in the IFPEX-2 methanol stream, it is removed through the slipstream that purges the water with methanol as the make-up stream for the IFPEX-1 step.
Copyright 1996 Offshore. All Rights Reserved.
