HYDROCARBON RECOVERY IN THE FISCHER-TROPSCH PROCESS
The invention provides an improved hydrocarbon recovery process of the Fischer-Tropsch process overhead stream using a scrubber system. Described is a process for recovering Fischer-Tropsch hydrocarbons from a reactor exit gas produced from a Fischer-Tropsch synthesis operation. The process includes (a) passing the reactor exit gas to a gas/liquid contactor; and (b) withdrawing a lean tail gas stream, a light hydrocarbon stream, and a water stream from the scrubber.
1 . A process for recovering Fischer-Tropsch hydrocarbons from a reactor exit gas produced: from a Fischer-Tropsch synthesis operation which comprises:
(a) passing the reactor exit gas to a gas/liquid contactor;
(b) withdrawing a lean tail gas stream, a light hydrocarbon stream, and a water stream from the scrubber.
2 . The process of claim 1 further comprising, recycling at least a portion of the water stream back to the gas/liquid contactor.
3 . The process of claim 1 further comprising, recycling at least a portion of the light hydrocarbon stream back to the gas/liquid contactor.
4 . The process of claim 1 further comprising, recycling at least a portion of the water stream and at least a portion of the light hydrocarbon stream back to the gas/liquid contactor.
5 . The process of claim 1 , wherein the reactor exit gas stream comprises methane and heavier hydrocarbons up to C 18 , carbon oxides, hydrogen, nitrogen and water vapor.
6 . The process of claim 1 , wherein the light hydrocarbon stream comprises C 1 to C 40 hydrocarbons.
7 . The process of claim 1 , wherein the percent recovery of light hydrocarbons from the FTR reactor exit gas is ≧90%.
8 . The process of claim 1 , wherein the gas/liquid contactor is operated at a temperature and pressure so that the light hydrocarbon stream contains at least 90% of the hydrocarbons present in the reactor exit gas.
9 . The process of claim 1 , wherein the operating temperature of the gas/liquid contactor is above 2° C. and the operating pressure of the scrubber is lower than the pressure of the FTR.
10 . The process of claim 2 , wherein the recycled water is cooled prior to entering the gas/liquid contactor.
11 . The process of claim 10 , wherein the water is cooled to a temperature of above 2° C.
12 . The process of claim 1 , wherein the gas/liquid contactor is packed with random or structured packing.
13 . The process of claim 1 , wherein the Fischer-Tropsch synthesis reaction is carried out in a slurry-type reactor.
14 . The process of claim 1 , wherein the light hydrocarbon stream is sent to an upgrading operation.
15 . The process of claim 1 , wherein the gas/liquid contactor is a scrubber.