Detailed introduction
　　Liquid fermentation is the process of fermentation using liquid as medium. The liquid fermentation tank is the tank to realize the liquid fermentation process. The volume of liquid fermentation tank is from small to large. It can be a double fermentation tank or a triple fermentation tank. The common fermentation tank is from 5L to 100000L. Wine fermentation, beer fermentation and milk fermentation belong to liquid fermentation. The liquid fermenter has the advantages of simple operation, high efficiency and cost saving.
　　The liquid fermentation tank is generally a fully sealed, vertical and clean container with functions of sterilization, cooling, heat preservation and stirring. The liquid fermentation tank is equipped with a jacket, which can be heated or cooled by heating or cooling medium respectively, so that the fermentation liquid can be fully dissolved oxygen and allocated by the operation of the agitator. The jacket forms vary according to the size of the liquid fermentation tank. There are many forms, such as standard jacket type, Miller plate type, half tube type, snake tube or tube type in the tank. Generally, small-scale liquid fermentation tanks adopt standard jacket type, while large-scale liquid fermentation tanks mostly adopt Miller plate type, semi-tubular type and tubular type. The key control of fermentation tank is temperature, so the heat transfer area must be sufficient to achieve the fermentation control temperature and good constant temperature control. The configuration of liquid fermentation tank system mainly includes transmission device, mechanical seal device, temperature control device, spotlight, sight mirror, mixing device, manhole feeding and opening, steam inlet, condensate outlet, material outlet, sewage outlet, sampling port, 360 degree universal cleaning ball, etc. Most of the liquid fermentation will produce foam, so liquid fermentation tanks need to set up defoaming paddles. The commonly used forms of defoaming paddles are sawtooth type, comb type and orifice plate type. The aperture of orifice plate type is about 10-20 mm. The length of defoamer is about 0.65 times the diameter of tank. Whether the liquid fermentor needs ventilation or not depends on the product and strain of fermentation, such as the common anaerobic fermentation tank for ethanol, acetone, butanol, lactic acid and other fermentation; the aerobic fermentation tank for the production of antibiotics, enzymes, yeast, amino acids, vitamins and other fermentation. Wine fermentation tank and beer fermentation tank belong to facultative anaerobic fermentation tank.