It saves the equipment such as air compressor, cooler, oil and water separator, air storage tank and general filter etc. in the air purification system and reduces the area occupied in the factory building. The investment of factory fermentation equipment can be reduced for about 30%. For example, in producing yeast by self-priming fermentation tank, the output of yeast per liter can reach 30~50 g. The fermentation period of yeast isshort, the yeast density in fermentation liquid is high and the waste after yeast is separated is few. The equipment has simple structure and high oxygen dissolution effect with convenient operation.