Wort cooling method

Wort cooling has one-stage cooling mode and two-stage cooling mode. Generally, the two-stage cooling method is more common. In terms of energy saving and control, one-stage cooling is preferred.

The two-stage plate heat exchanger is composed of front and rear sections, and a middle plate is installed between the two sections. Cold water is used for cooling in the first stage, and refrigerant is used for cooling in the latter stage. The cooling water temperature in the front section is required to be below 20°C. After the front section is cooled, the temperature of the wort is required to drop to 40°C~50°C; Reduce to fermentation temperature. Remarks: The water after heat exchange in the previous stage can be used as feed water.

The plate heat exchanger has a resistance of 0.25~0.35MPa, and both wort and coolant need to be pumped in, and the wort at 90°C~95°C flowing out of the rotary sedimentation tank is directly cooled to the fermentation temperature. The cooling time is best controlled within 1h to match the production capacity of the rotary sedimentation tank. Therefore, the production capacity of the plate heat exchanger is required to be larger.

After the plate heat exchanger is used, it must be fully circulated with hot water and hot alkaline water for washing and sterilization to prevent scaling and affect the heat exchange effect.

In the one stage of cooling, the brewing water is first cooled to 3°C~4°C by ammonia direct cooling (this water is commonly known as ice water), and then a one-time heat exchange is performed with the hot wort in the plate heat exchanger, and the wort is cooled to the fermentation temperature. At the same time, the ice water is heated to about 75 ℃ ~ 80 ℃. Remarks: This water can be used directly as washing dregs water.

The technical points of one-stage cooling and the preparation of ice water：

A. The inlet temperature of wort is about 95℃.

B. The cooling time is best controlled within 1h, too long cooling time will affect the utilization rate of the rotary sedimentation tank and the quality of the wort.

C. The pumping pressure of wort and ice water is 0.1~0.15MPa

D. The consumption ratio of wort and ice water is 1:(1.2~1.4).

E. The temperature of water for cleaning and sterilization is 85℃~90℃; the temperature of washing with alkaline water is 75℃~80℃.

F. The time for circulating cleaning and sterilization with a pump is 20~30min

G. Cooling medium—ice water temperature 3℃~4℃

Preparation of ice water: The brewing water is pumped to the ammonia evaporator, where it is cooled to 3°C to 4°C, and stored in an ice water tank for later use. The ammonia evaporator adopts a multi-pass heat exchanger with a tube-sheet structure. The inside of the tube is a water channel, and the refrigerant evaporates between the tubes. Ice water should be prevented from freezing when preparing ice water, the flow rate of water in the pipe should be greater than 0.8m/s, and the evaporation pressure of ammonia should be controlled within the range of 0.2~0.3MPa.