Fermentation method
View Patent ↗This invention relates to the integration of an ammonia production process with a fermentation process to produce products such as alcohols and/or acids in addition to ammonia. In a specific embodiment, a natural gas stream comprising methane is passed to a reforming zone to produce a substrate comprising CO and H 2 . The substrate is next passed to a bioreactor containing a culture of one or more microorganisms and fermenting the culture to produce one or more fermentation products comprising alcohols and/or acids and an exhaust stream comprising CO 2 , and H 2 . The exhaust stream can then be passed to a separation zone to remove at least a portion of the CO 2 and produce a purified exhaust stream comprising H 2 which is then passed to an ammonia production zone and is used to produce ammonia.
1. An integrated ammonia production and fermentation method for producing one or more products from a gas stream comprising methane, the method comprising;
a) converting at least a portion of a gas stream comprising methane to a substrate comprising CO, CO 2 and H 2 ;
b) passing at least a portion of the substrate to a bioreactor containing a culture of one or more carboxydotrophic bacteria, anaerobically fermenting at least a first portion of the substrate comprising CO and H 2 to produce one or more products comprising alcohols and/or acids and an exhaust gas stream comprising hydrogen and carbon dioxide;
c) passing a second portion of the substrate to a water gas shift reactor operated at conditions to produce an effluent stream comprising CO 2 and H 2 ;
d) passing the exhaust gas stream and the effluent stream of (c) to a separation zone operated at conditions to separate at least a portion of the CO 2 and produce a second effluent stream rich in H 2 and a CO 2 stream; and
e) passing the second effluent stream to an ammonia synthesis zone operated at conditions to produce ammonia.
2. The method of claim 1 wherein the gas stream is converted to a substrate stream comprising CO, CO 2 and H 2 by a steam reforming process.
3. The method of claim 2 wherein the substrate stream is passed into a secondary reformer, wherein at least a portion of methane remaining in the substrate stream is converted to CO, CO 2 and H 2 , prior to being passed to the bioreactor.
4. The method of claim 1 wherein the one or more products is selected from the group consisting of ethanol; 2,3-butanediol, and acetic acid.
5. The method of claim 1 wherein prior to passing the effluent stream to the ammonia synthesis zone, it is passed to a methanation zone to remove traces of CO.
6. The method according to claim 1 wherein the carboxydotrophic bacterium is selected from the group comprising Moorella, Clostridium, Ruminococcus, Acetobacterium, Eubacterium, Butyribacterium, Oxobacter, Methanosarcina, Methanosarcina , and Desulfotomaculum.
7. The method of claim 6 wherein the carboxydotrophic bacterium is Clostridium autoethanogenum.
8. An integrated ammonia production and fermentation method for producing one or more products from a gas stream comprising methane, the method comprising;
a) converting at least a portion of a gas stream comprising methane to a substrate comprising CO, CO 2 and H 2 ;
b) passing the substrate to a bioreactor containing a culture of one or more carboxydotrophic bacteria, anaerobically fermenting at least a portion of the substrate to produce one or more products comprising alcohols and/or acids and an exhaust gas stream comprising hydrogen and carbon dioxide;
c) passing the exhaust gas stream to a separation zone operated at conditions to separate at least a portion of the CO 2 and produce a second effluent stream rich in H 2 and a CO 2 stream; and
d) passing the second effluent stream to an ammonia synthesis zone operated at conditions to produce ammonia.
9. The method of claim 8 wherein the carboxydotrophic bacterium is selected from the group comprising Moorella, Clostridium, Ruminococcus, Acetobacterium, Eubacterium, Butyribacterium, Oxobacter, Methanosarcina, Methanosarcina , and Desulfotomaculum.
10. The method of claim 9 wherein the carboxydotrophic bacterium is Clostridium autoethanogenum.