US 12,065,636 B2
High hydrogen utilization and gas recycle
Gary J. Smith, North Yorkshire (GB); Paul S. Pearlman, Thornton, PA (US); and Gregory S. Kirby, Avondale, PA (US)
Assigned to INV NYLON CHEMICALS AMERICAS, LLC, Wilmington, DE (US)
Filed by INV NYLON CHEMICALS AMERICAS, LLC, Wilmington, DE (US)
Filed on Apr. 1, 2019, as Appl. No. 16/372,106.
Claims priority of provisional application 62/650,590, filed on Mar. 30, 2018.
Claims priority of provisional application 62/650,575, filed on Mar. 30, 2018.
Prior Publication US 2019/0316072 A1, Oct. 17, 2019
Int. Cl. C12M 1/00 (2006.01); C12M 1/34 (2006.01); C12P 7/625 (2022.01)
CPC C12M 29/24 (2013.01) [C12M 41/32 (2013.01); C12M 41/34 (2013.01); C12P 7/625 (2013.01)] 20 Claims
 
1. A method for recycling an off-gas stream in a gas fermentation biosynthetic system, the method comprising:
introducing a supply gas to a culture of a chemoautotrophic organism in a gas fermentation reactor system, wherein the organism is capable of synthesis of one or more biosynthetic products, wherein the concentration of hydrogen in the supply gas is from 86.5% to 95% (v/v), the concentration of carbon dioxide in the supply gas is from 1% to 4% (v/v), the concentration of oxygen in the supply gas is greater than 7.4%, and the concentration of nitrogen in the supply gas is less than 5% (v/v), wherein the concentrations of one or more target components in the supply gas are each independently within a target concentration range, and wherein the one or more target components are selected from the group consisting of hydrogen, carbon dioxide, and oxygen;
maintaining a gaseous oxygen concentration in a headspace of the gas fermentation reactor system at 3.5% to 4.5%;
producing, with the culture, an off-gas;
forming a recycle gas from at least a portion of the off-gas, wherein the recycle gas comprises at least 50% (v/v) of the off-gas produced with the culture;
measuring the concentrations of each of the one or more target components in the recycle gas;
calculating an amount of each of the one or more target components to be combined with the recycle gas to form the supply gas having concentrations of the one or more target components within the target concentration ranges; and
introducing the recycle gas and one or more supplemental gas streams comprising the calculated amounts of each of the one or more target components to the culture, wherein at least one of the one or more supplemental gas streams has a hydrogen concentration that is greater than 50%, less than a hydrogen concentration of the supply gas, and has an absolute difference in hydrogen concentration from the supply gas of 10% or more;
wherein the method has a total hydrogen conversion rate of 96% or more of the hydrogen in the supply gas.