Application: To recover ethane and higher components from natural gas streams. This process is especially adequate with lean and semi-lean gas streams.
The inlet gas is treated and conditioned to remove contaminants and water that cannot be processed cryogenically. The gas is partially condensed to knock out heavy hydrocarbons, and is sent to a cold separator. Removed liquids are sent to the demethanizer column, while the gas is sent to a turboexpander. The stream from the expander is sent to the demethanizer column. To increase the recovery level, a recycle/reflux stream is taken from the residue gas and is precooled, extracting refrigeration from the demethanizer column. The reflux is finally subcooled and sent to the top of the demethanizer.
This process is also adapted for the rejection of ethane and production of LPG and heavier streams. Recoveries for ethane product are 95+%. Energy consumption is between 50 and 70 HP/million scfd depending on gas conditions.
Operating conditions: Ample range of pressures and temperatures. Hydrocarbon liquid content less than 3.5 gal/thousand scf.
Licensors: Randall Gas Technologies, ABB Lummus Global Inc.