Patent ID: 8535919

Claim:
A process for converting a feed gas stream comprising feed gas components of CO, CO 2 , and H 2 into a liquid product by contact with an aqueous fermentation liquid wherein the liquid product reduces the surface tension of the fermentation liquid, said process comprising: a) retaining a portion of the aqueous fermentation liquid in a fermentation vessel; b) producing said liquid product by contact of the feed gas stream with microorganisms suspended in the aqueous fermentation liquid and retained in the fermentation vessel; c) withdrawing aqueous fermentation liquid containing the liquid product from said fermentation vessel at a withdrawal point on said fermentation vessel to provide a withdrawn aqueous liquid; d) recovering the liquid product from the withdrawn aqueous fermentation liquid of step c) in a separation zone to recover the liquid product and to recover aqueous fermentation liquid; e) returning a first portion of the recovered aqueous fermentation liquid from step d) to the fermentation vessel and passing a second portion of the recovered aqueous fermentation liquid from step d) to a recycle loop that continuously circulates a recycle liquid therein; f) recovering an off-gas stream from a gas phase located at an upper portion of the fermentation vessel; g) passing the off-gas stream and the recycle liquid of step e) to a first gas-liquid injector located at a first elevation and discharging a first gas and liquid mixture from the first gas-liquid injector into the recycle liquid of step (e); h) pumping the recycle liquid from the first gas liquid injector downward for a distance of at least 10 meters to a gas separation tank located at a second elevation, recovering a diluent gas from the gas separation tank and passing the recycle liquid from the gas separation tank back into the recycle loop; i) pumping the recycle liquid from the gas separation tank upward in the recycle loop to a stripping vessel, recovering a CO 2 containing gas from the stripping vessel and passing the recycle liquid from the stripping vessel back into the recycle loop and to the first injector of step g), j) pumping at least one of the first portion of aqueous fermentation liquid from step (e) and a stream of aqueous fermentation liquid withdrawn from the fermentation vessel together with the diluent gas of step h) to a second gas-liquid injector and discharging a second gas and liquid mixture into a lower portion of the fermentation vessel at discharge point located on the fermentation vessel at a third elevation that is below the first elevation of step g) and above the second elevation of step h); and, k) adding at least a portion of the feed gas stream by at least one of: direct addition to the fermentation vessel; addition to the off-gas stream of step f); and, addition to the diluent gas for injection into the fermentation vessel with the diluent gas as described in step h).