Brief introduction to biological fermentation tank

Biological fermentation tanks are widely used in dairy products, beverage bioengineering, pharmaceuticals, fine chemicals and other industries. In terms of biological fermentation tank, the commonly used fermentation tank equipment is mechanical stirring fermentation, and its sterilization effect directly affects whether the fermentation can be carried out normally. Its working principle is: use the air nozzle to spray high-speed air, and the air is dispersed in the liquid in the form of bubbles. On the ventilation side, the average density of the liquid decreases. On the non-aerated side, the liquid density is high, so there is a density difference between the liquid on the aerated side and the liquid on the aerated side, thus forming a liquid circulation in the fermentation tank. There are many kinds of biological fermentation tanks, including internal circulation pipe, external circulation pipe, tension pipe and vertical baffle. The external circulation pipe is designed outside the tank body, and there are two internal circulation pipes inside the tank body. In the biological fermentation tank, the liquid level in the tank is not higher than the outlet of the circulating pipe and not lower than the outlet of the circulating pipe. The biological fermentation tank has the advantages of low energy consumption and less liquid frying. Under the same energy consumption, its oxygen transfer capacity is much higher than that of ordinary fermented cans.

Let's talk about the main advantages of the biological fermentation tank: 1. The biological fermentation tank has simple structure, simple basic principle, and lower energy consumption than the slurry reactor with stirring paddle; 2. Relying on gas to produce directional circulation instead of centrifugal pump mechanical equipment, its flow form is determined, the liquid circulation is strong, and there are no moving parts inside, so it is important to use small shear stress and uniform energy dissipation for shear sensitive materials; 3. Compared with the traditional fermentation tank, the flow range of gas and liquid in the biological fermentation tank is much larger. 4. The gas supply efficiency of the biological fermentation tank is high. The gas supply in the riser can be greater than that in the bubble reactor, which is conducive to the aerobic reaction; 5. The fluidization effect can be solid particles, even the heavier particles can remain completely suspended.

Of course, the biological fermentation tank also has some disadvantages: 1. The biological fermentation tank needs very large air throughput; 2. Poor mixing and contact between phases; 3. When the circulating organisms and operating conditions change, the amount of substrate, nutrients and oxygen cannot be consistent; 4. Mixing and ventilation are coupling problems. It is difficult to improve mixing conditions without changing ventilation.

Sterilization method of biological fermentation tank: 1. Before sterilization of biological fermentation tank, the air filter connected to biological fermentation tank shall be sterilized with steam and dried with air. At the same time of sterilization of the real tank, discharge and flush the sewage in the transmission pipeline, then pump the prepared culture medium into the fermentation tank, and start the stirrer for sterilization. 2. Sterilization of biological fermentation tank: first open each exhaust valve, and introduce steam into jacket or coil for preheating. When the oil tank temperature rises to 80~90, remove the exhaust valve and slowly turn it down. Then the steam is directly introduced into the fermentation tank from the air inlet, air outlet and sampling port to raise the temperature of the tank to 118~120, and maintain the tank pressure of the fermentation tank within the range of 0.09~0.1Mpa (gauge pressure) for about 30 minutes. 3. Sterilization of empty fermentation tank refers to sterilization of fermentation tank. Generally, keep the tank pressure at 0.15~0.2Mpa and the tank temperature at 125~130 for 30~45 min; The total steam pressure shall not be lower than 0.3~0.35Mpa, and the service steam pressure shall not be lower than 0.25~0.3MPa. 4. In-situ sterilization refers to the sterilization without changing the tank structure in production, which generally adopts online steam sterilization. Offline sterilization can be understood as taking down the fermentation tank for sterilization, and the small fermentation tank can be moved to the sterilization tank for sterilization.