| abstract |
The present invention describes a process for separation and purification of a fermentation gas product from a fermenter off-gas containing fermentation product, volatile impurity, bio-product impurity 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 impurity, bio-byproduct impurity 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 impurity, bio-byproduct impurity and water through the membrane, resulting in an product rich retentate stream. The fermentation gas product is separated from the fermenter off-gas in a single membrane stage to produce purity purified retentate stream. in accordance with this embodiment of the invention, the fermenter off-gas ( 2 ), comprising the fermentation gas product, volatile impurities, bio-byproduct impurities and water, passes through a blower ( 201 ) that transports it to a gas holder ( 202 ), in order to smooth the process fluctu ations. Stream ( 11 ) exits the gas holder ( 202 ) and is compressed in a multi-stage compressor ( 203 ), from which bio-byproduct and water are removed through stream ( 4 ). The compressed stream ( 12 ) enters the membrane module ( 204 ), which permeates the volatile impurities, disposing them in stream ( 13 ). The process may be still conducted in a 2 -stage membrane system in accordance with the present invention. |