Gas-fed fermentation reactors, systems and processes

A process for stimulating production of biomass comprising:

• flowing through a loop section of a loop reactor, a multi-phase mixture of a gas and a liquid culture medium, the multi-phase mixture containing a biomass, the loop section including a loop section centerline and a portion sloped upward in the direction of flow of the multi-phase mixture in the loop section;
• introducing nutrients into the multi-phase mixture;
• introducing methane and oxygen into the multi-phase mixture;
• passing the multi-phase mixture of a gas and a liquid culture medium through a first non-vertical pressure reduction zone of the loop reactor, the first non-vertical pressure reduction zone of the loop reactor including a control valve and an eccentric expander;
• separating the multi-phase mixture of a gas and a liquid culture medium into a gas phase and a liquid phase downstream of the first non-vertical pressure reduction zone;
• flowing the gas phase and the liquid phase separated from the multi-phase mixture of a gas and a liquid culture medium into a gas/liquid separation vessel through an inlet to the gas/liquid separation vessel, the inlet to the gas/liquid separation vessel including a centerline;
• and
• removing the liquid phase from an outlet of the gas/liquid separation vessel and delivering the removed liquid phase to an inlet of the loop section, a vertical distance between a centerline of the loop section at the inlet of the loop section and the centerline of the inlet to the gas/liquid separation vessel being less than 8 meters.