(435d) Comparison of Cost and Design between Stirred Tank Reactors and Bubble Column Reactors

Fermentation is a bioprocessing technique that is utilized in multiple applications. During the mass transfer portion of the fermentation process, Bubble Column Reactors (BCRs) and Stirred Tank Reactors (STRs) are widely used. Interest in determining the best economic reactor solution is being expressed in the industry. Manufacturers of both STRs and BCRs are looking for ways to gain market share with process-proven and cost-efficient solutions.

An investigation into the overall running and capital costs between the optimal BCR conditions and the optimal STR conditions is being conducted. This investigation will compare BCRs versus STRs at a standard tank volume with low and high oxygen uptick rates. The low and high oxygen uptick rates will cater specifically to BCR or STR standard designs.

Determining the optimum Oxygen Transfer Rate (OTR) in investigations between a BCR and STR is required to assist with selecting the proper sizing for each reactor. OTR determination is measured in the lab scale using two oxygen probes located at the bottom tangent line of the vessel, and 1” below the liquid surface, at the top of the vessel, a dissolved oxygen meter to measure the oxygen in the fluid, and a methodology of stripping the oxygen from the fluid.

OTR is just one consideration when choosing between a BCR and STR. A second consideration is overall blend time. Blend time is measured in the lab scale by using two to four conductivity probes and a saturated salt solution. By reviewing the blend time and OTR results together, the proper sizing for each specified case can be determined.

Looking at the compressor size, agitator requirements, and power consumption are a few of the driving factors that push industry personnel into a BCR or STR. Startup versus long-term costs is also a contributing factor. This investigation will look at all the contributing factors when running low and high oxygen uptick rate cases and review whether the standard choices for these cases are practically sound.