Cooling system is the heart of a brewery in which there are many areas requiring refrigeration such as:
Rapid cooling of wort:
Rapid cooling of flower material behind whirlpool from 96 ÷ 980C to 6 ÷ 80C is a significantly important step. The required time is 30 ÷ 45 minutes. If notrapidly cooled, especially in the temperature range of 50 to 20 ° C, it will promote the growth of harmfulmicrobial groups to beer fermentation. This may reduce the quality of beer. The most popular cooling method in our country is toexchange heat between beer and cold water of 20C through plate heat exchanger.
Process of beer fermentation and preservation
The characteristic of beer fermentation is that it must be maintained at low temperature.
The first stage of fermentation is the main stage. At this stage, the substrate consumption is strong and a large amount of sugar is converted into alcohol and CO2. The product of fermentation process is new beer which has opaque colour with specific smell and taste. However, the product of this stage cannot be used yet. The temperature in the main fermentation process is from 7 ÷ 90C and fermentation time is about 7 days.
After the main fermentation process, secondary fermentation- and brewing stage will be processed. This process is slow, consuming a small amount of sugar. At this stage,beer isfiltered and has smoother flavour. The product of the secondary fermentation is a mild alcoholic beverage with CO2, aroma, mild sweetness and bitterness. This is the product of complex biochemical process that takes place in the long-time low-temperature heating environment. The temperature in the secondary fermentation stage is from 2 ÷ 30C in 14 days. Total fermentation time is about 21 days.
Beer after secondary fermentation will befiltered to remove yeast to clarify beer. Before filtering, beer temperature will be lowered from 0 to -10C. During filtering, lost CO2 will be added along withantioxidant additives and stabilizers.The product of this filtration process is called fresh beer (bright beer) which is stored in tanks and prepared for bottling process (includingpasteurizing, labeling, printing andfilling intotanks).
Production of carbonated water
Carbonated water is used for the purpose of mixing beer during the filtration process to adjust the sugar required by the technology of level for each beer’s type making. With a strict requirement for quality, the production of carbonated water consumes a significant share of energy in breweries.
Initially the water supplied from the brewing tank will be run through a heat exchanger, exchanging temperature with steamto raise the temperature from ambient temperature to 800C then going into degassing tank. At the top of the tank, the water will be poured from high position to make gas molecules in the water separate easily. At the bottom of the tank, 6 bars blown from the bottom push oxygen out. The water from the bottom of degassing tank will be pumped back into the heat exchanger with the water inlet (with lowering the temperature from 800C to 500C). Water, subsequently, is exchanged with Glycol-40C to cool down from 500C to 3 – 40C and put into an anaerobic tank.
CO2 recovery system
Cooling energy uses CO2 recovering system to condense CO2 into liquid before entering containers.
Other cooling energy consumption areas
In other areas, there is a need for refrigeration such as: hopping room, ferment preserving room, beer filtering room etc.
LAYERED REFRIGERANT TECHNOLOGY system PROCESS
On NH3 refrigerant side: After passing the compressor, NH3 refrigerant is pressurized to Pk pressure (corresponding to the condensing temperature of 35-37 degrees Celsius) and then goes to the condenserin which NH3 gas is condensed into liquid and led to a high pressure container From a high-pressure liquid tank,NH3 is released into a low pressure tank at Po pressure(corresponding to the evaporating temperature (-7) – (- 8) degree Celsius). A low pressureliquid NH3 is delivered to the evaporator plate by gravity method. Liquid NH3 in evaporator cools Glycol then is brought to low pressure tank. NH3 gas in lower tank isdrawn to the suction head of the refrigeration compressor and compressed to the pressure of Pk to complete a closed cycle.
On Glycol refrigerant side: -4-degree Glycol is pumped to areas to cool the technological process then is directed to the tank containing hot glycol (about 1 degree Celsius). Glycol will then be pumped to evaporator to be cooled down to 4-degree and poured to a 4-degree Glycol tank to continue cooling, which ends a closed loop.