The previous brewery savings article discussed the importance of equipping hot and cold liquor tanks to save energy and reduce emissions. For small to medium size breweries, it may be more cost effective to focus on these tanks only. However, for breweries with a production of 10 million liters per year or more, it may be more feasible to consider the implementation of an energy recovery system during the construction phase.
First, let's examine the operating principles of hot and cold liquor tanks. These tanks can serve as part of the energy recovery system discussed in this article.
The whole brewery energy recovery system typically consists of a hot liquor tank, cold liquor tank, plate changer, underback, kettle steam condenser and energy storage tank.
The amount of hot water produced by exchanging heat can sometimes exceed the brewery's needs. In order to fulfill their needs, the brewery requires high-temperature water that can be used for heating with minimal energy consumption. In addition, any excess hot water is stored in an energy storage tank divided into high and extra-high temperature zones. The temperature of the water in the high-temperature zone is approximately 78°C, while the extra-high-temperature zone has a temperature of around 97°C. Due to the relationship between the density and temperature of the water, a thermocline is naturally formed in the vessel. This results in a high-temperature zone in the lower half and an extra-high-temperature zone in the upper half, which may be incompatible with each other. The ratio of 97°C superheated water and 78°C hot water in the energy storage tank can be adjusted according to specific requirements. Depending on the structure of the storage tank, the height of the mixing section may also vary.
How the energy recycle system works?
When wort boils, it produces vapor that contains a significant amount of heat. Evaporating 100L of water generates enough heat energy to raise the temperature of 800 liters of water to 80°C. In small-scale breweries, the vapor is condensed using tap water, and the resulting condensate is collected for wastewater discharge. However, this process can be a significant waste of energy in large breweries.
A heat exchanger will be installed in the condenser that is connected to the brew kettle. Vapor from the brew kettle enters the condenser's tube heat exchanger, where it is condensed by 78°C high-temperature water to about 85°C. The high-temperature water flows in the opposite direction and is heated to 97°C. It then enters the upper part of the energy storage tank. Then, using the 12°C cold water from the cold liquor tank, the 85°C condensate is cooled to 30°C. At the same time, the 12°C cold water is heated to 80°C and returned to the hot liquor tank.
Superheated water (97°C) from top of energy storage tank is used to heat 72 °C wort from the underback to 95 °C via plate heat exchanger, thus reducing thermal energy required for boil. The superheated water, which has now cooled down to 78 °C, is then transferred to the lower half of the energy storage tank.
Tiantai offers a range of methods aimed at establishing a sustainable future for our customers. The technology reduces the primary energy consumption of the brewery to produce hot water and reduces the heating time to boil the wort by 70%, thereby reducing operating costs and CO2 emissions.
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