Proper cleaning of fermenter

The dirt on the fermenter wall is a mixture of inorganic matter and organic matter, which is difficult to clean with a single cleaning agent. If the fermenter is cleaned using only caustic soda, it only serves to remove organic matter. Only when the cleaning temperature reaches 80 ℃ above, can have better cleaning effect; When cleaning with a single nitric acid, it has a certain effect on inorganic substances, but has almost no effect on organic matter. Therefore, alkaline cleaning solution and acid cleaning solution are needed for fermenter cleaning. The fermenter is cleaned before sterilization. Only when the dirt inside the tank is thoroughly cleaned can it be considered effective sterilization.

A common cleaning method used in modern breweries is cleaninginplace (CIP), which is to clean and sterilize equipment and pipes under closed conditions without removing parts or fittings of the equipment. Large containers such as fermenters cannot be cleaned by filling them with cleaning solution. In situ cleaning of the fermenter is carried out through the scrubber cycle. There are two types of scrubber: stationary wash ball and rotary jet. The cleaning solution is sprayed through the scrubber onto the inner surface of the tank and then flows down the tank wall. Generally, the cleaning solution will form a film that adheres to the walls of the tank. This mechanical effect is very small, cleaning effect depends mainly on the chemical action of the cleaning agent.

The action radius of the fixed spherical scrubber is 2m. For the horizontal fermenter, multiple scrubbers must be installed. The pressure of washing liquid at the nozzle outlet of the scrubber shall be 0.2~0.3MPa; For the vertical fermenter and the pressure measuring point at the outlet of the washing pump, it is necessary to consider not only the pressure loss caused by pipe resistance, but also the influence of height on the cleaning pressure. When the pressure is too low, the washing radius is small, the flow rate is insufficient, the spray cleaning liquid can not cover the tank wall; When the pressure is too high, the cleaning liquid will form fog, which can not form water film along the tank wall, or spray the cleaning liquid rebound, reducing the cleaning effect.

The cleaning equipment is dirty and the tank diameter is large (d> 2m), the rotary jet scrubber is generally used. By increasing the outlet pressure of the scrubber (0.3~0.7MPa), the washing radius is increased, the mechanical action of washing is enhanced, and the scaling effect is increased. Compared with ball scrubber, rotary jet scrubber can use lower cleaning fluid flow. When the washing medium passes through, the scrubber uses the recoillation of the fluid to rotate, and the washing and flow air are carried out alternately, thus improving the cleaning effect.

As previously stated in the estimation of cleaning fluid flow, fermenter cleaning requires a certain flushing intensity and flow. In order to ensure that the thickness of the fluid flow layer is sufficient to form continuous turbulence, it is necessary to pay attention to the flow rate of the cleaning pump.