(1) The fermentation process will produce a large amount of organic matter such as protein, hop resin, polysaccharide, yeast, and inorganic matter such as calcium oxalate and sulfate. After the fermentation tank is emptied, the organic matter and inorganic dirt will adhere to the tank wall, showing a yellowish-brown color. . When the amount of tartar is large, the surface appears white, just like the epidermis of the saline-alkali ground, the inorganic and organic matter are intertwined with each other.
The use of caustic soda during cleaning only has an effect on removing organic matter. Only when the cleaning temperature reaches above 80 °C will it have a better cleaning effect. When cleaning, a single nitric acid is used for cleaning, which only has a certain effect on inorganic substances and is almost ineffective on organic substances. The contamination on the wall of the fermentation tank is a mixture of inorganic and organic substances, which is difficult to clean with a single cleaning agent. Therefore, some breweries will carry out a major cleaning of the fermentation tank every year to thoroughly clean the fermentation tank.
(2) Part of the anti-corrosion layer on the wall of the fermentation tank is damaged. After repairing, the surface finish is obviously reduced, which makes it difficult to clean the dirt on the tank wall. The wear or blockage of the tank washer or the washer ball results in incomplete cleaning of some fermenters and a lot of dirt accumulation. Many factors will cause the fermentation tank to produce a lot of dirt after several years of use. For example, a certain amount of dirt has accumulated on the tank wall, which is difficult to completely remove by conventional cleaning processes. Therefore, every 4 to 5 years, it is a better method to use the off-season of production to carry out deep cleaning of the fermentation tank.
The outstanding difference between the fermenter and other industrial equipment is that the requirements for purebred cultivation are high, almost reaching a very demanding level. Therefore, the rigor of the fermentation tank and the high reliability of the operation are the distinguishing features of the fermentation industry. In order to obtain greater economic benefits in the modern fermentation industry, fermentation tanks tend to be larger and more automated.