The height-diameter ratio of the fermentation tank is generally between 1.7 and 2.5.
A large ratio is beneficial to heat transfer and dissolved oxygen, and its agitation shear force is large.
The stirring device of the fermentation tank includes mechanical stirring and non-mechanical stirring.
But achieving both goals at the same time is sometimes contradictory.
For example, to achieve the mixing function, a large diameter agitator and low speed operation are required; while to improve the effect of dispersing the bubbles, multiple blades, a small diameter agitator and a high rotation speed operation are required.
The input power of the motor is determined by the form of the agitator and other fermenter components.
In order to improve the efficiency of mixing, heat transfer and mass transfer, four baffles are often installed in the bioreactor.
The width of the baffle is 10% ~ 12% of the diameter of the fermentation tank. The wider the baffle, the better the mixing effect.
In the aerobic fermenter, the compressed air in the sterile air system is injected into the fermenter through the air distributor. Air distributors are divided into single-hole tubular type and multi-hole tubular type.
They are installed differently, but are generally installed at the bottom of the mixer. Care should be taken to prevent the pores from being blocked by bacteria or solid particles in the fermentation broth.
The upper limit of the air velocity is that the agitator can effectively disperse the air, which is related to the shape and speed of the agitator.