Fermentation hydrocarbon gas products separation via membrane

Abstract

Disclosed herein is a process for separation and purification of a fermentation gas product from a fermenter off-gas containing a fermentation product, volatile impurities, bio-product impurities and water, based on a membrane system. In one preferred embodiment of the present invention, the process of separating and purifying a fermentation product from a fermenter off-gas, containing the fermentation product, volatile impurities, bio-byproduct impurities and water, comprises the steps of: (a) compressing the fermenter off-gas and feeding it into a membrane module, and (b) selectively permeating the volatile impurities, bio-byproduct impurities and water through the membrane, resulting in a product rich retentate stream. The fermentation gas product is separated from the fermenter off-gas in a single membrane stage to produce a purified retentate stream. In accordance with this embodiment of the invention, the fermenter off-gas (), comprising the fermentation gas product, volatile impurities, bio-byproduct impurities and water, passes through a blower () that transports it to a gas holder (), in order to smooth the process fluctuations. Stream () exits the gas holder () and is compressed in a multi-stage compressor (), from which bio-byproduct and water are removed through stream (). The compressed stream () enters the membrane module (), which permeates the volatile impurities, disposing them in stream (). The process may be still conducted in a 2-stage membrane system in accordance with the present invention.