PROCESSES FOR ENHANCING THE PERFORMANCE OF LARGE-SCALE, STIRRED TANK ANAEROBIC FERMENTORS AND APPARATUS THEREFOR
First Claim
1. A process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide and hydrogen in an aqueous menstruum containing microorganisms suitable for converting said substrate to oxygenated organic compound in a deep, continuously stirred tank reactor comprising:
- a) maintaining under continuous mechanical stirring in a reactor an aqueous menstruum containing said microorganisms, said aqueous menstruum being under anaerobic fermentation conditions, and said aqueous menstruum having an upper portion with a head space above the upper portion and a lower portion and having a depth of at least 10 meters in said reactor; and
b) continuously supplying gas feed comprising said gas substrate to said aqueous menstruum by injection using in a motive liquid to form a stable gas-in-liquid dispersion in the aqueous menstruum, bioconverting carbon monoxide and hydrogen and carbon dioxide to oxygenated organic compound and providing off-gas from the aqueous menstruum in the head space,c) withdrawing from the head space of said reactor at least a portion of the off-gas; and
d) admixing at least a portion of the withdrawn off-gas with the gas substrate in an amount sufficient to (i) achieve a conversion efficiency of the total moles of carbon monoxide and hydrogen in the gas substrate to oxygenated organic compound of at least about 80 percent and (ii) attenuate the risk of carbon monoxide inhibition of the microorganism used for the bioconversion,wherein the mechanical stirring is at a rate sufficient to provide relatively uniform liquid phase composition within the aqueous menstruum without unduly adversely affecting the gas-in-liquid dispersion.
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Abstract
Processes and apparatus are disclosed for the low energy, anaerobic bioconversion of hydrogen and carbon monoxide in a gaseous substrate stream to oxygenated organic compounds such as ethanol by contact with microorganisms in a deep, stirred tank fermentation system with high conversion efficiency of both hydrogen and carbon monoxide. Gas feed to the reactor is injected using a motive liquid to form a stable dispersion of microbubbles thereby reducing energy costs, and a portion of the off-gases from the reactor are recycled to (i) achieve a conversion of the total moles of carbon monoxide and hydrogen in the gas substrate to oxygenated organic compound of at least about 80 percent and (ii) attenuate the risk of carbon monoxide inhibition of the microorganism used for the bioconversion.
8 Citations
20 Claims
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1. A process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide and hydrogen in an aqueous menstruum containing microorganisms suitable for converting said substrate to oxygenated organic compound in a deep, continuously stirred tank reactor comprising:
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a) maintaining under continuous mechanical stirring in a reactor an aqueous menstruum containing said microorganisms, said aqueous menstruum being under anaerobic fermentation conditions, and said aqueous menstruum having an upper portion with a head space above the upper portion and a lower portion and having a depth of at least 10 meters in said reactor; and b) continuously supplying gas feed comprising said gas substrate to said aqueous menstruum by injection using in a motive liquid to form a stable gas-in-liquid dispersion in the aqueous menstruum, bioconverting carbon monoxide and hydrogen and carbon dioxide to oxygenated organic compound and providing off-gas from the aqueous menstruum in the head space, c) withdrawing from the head space of said reactor at least a portion of the off-gas; and d) admixing at least a portion of the withdrawn off-gas with the gas substrate in an amount sufficient to (i) achieve a conversion efficiency of the total moles of carbon monoxide and hydrogen in the gas substrate to oxygenated organic compound of at least about 80 percent and (ii) attenuate the risk of carbon monoxide inhibition of the microorganism used for the bioconversion, wherein the mechanical stirring is at a rate sufficient to provide relatively uniform liquid phase composition within the aqueous menstruum without unduly adversely affecting the gas-in-liquid dispersion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for anaerobic bioconversion of a gas substrate comprising carbon monoxide and hydrogen in an aqueous menstruum containing microorganisms suitable for converting said substrate to oxygenated organic compound comprising:
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a) a deep, continuously-stirred tank reactor having a height of at least 10 meters and at least one mechanical stirrer, said tank reactor being adapted to contain under anaerobic fermentation conditions an aqueous menstruum and defining a head space adapted to receive off-gas from the aqueous menstruum; b) at least one injector in the tank reactor adapted to provide a gas-in-liquid dispersion; c) a gas feed supply line in fluid communication with said injector adapted to provide fresh gas feed containing said substrate; d) a motive liquid supply line adapted to provide liquid to said injector, said motive liquid supply line being in fluid communication with the stirred tank reactor to obtain at least a portion of the motive liquid to said injector; e) an off-gas exhaust line from the head space of the tank reactor; and f) a recycle off-gas line in fluid communication between the off-gas exhaust line and the gas feed supply line adapted to provide recycle off-gas for admixture with gas substrate. - View Dependent Claims (19, 20)
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Specification