Basic structure and performance of conical fermenter
1. Features
(1) It has a cone bottom with an angle between 60° and 90°, and it is convenient to recover yeast after (main) fermentation. In order to ensure good filterability of beer, yeast strains with good coagulation performance are mostly used.
(2) The tank body is equipped with a cooling jacket, and the cooling capacity can meet the cooling requirements of the process. The cylindrical part of the tank is equipped with 2~3 sections of cooling jacket, and the cone part is equipped with a section of cooling jacket. This structure is conducive to the settlement and preservation of yeast.
(3) The conical tank is a closed tank, which can recover CO2, and can also be used for CO2 washing; it can be used as a fermentation tank and a wine storage tank.
(4) The natural convection of the liquor in the fermenter is relatively strong. The higher the tank, the stronger the convection. The convection intensity is related to the shape of the tank, the size of the capacity and the control of the cooling system.
(5) The conical tank has a considerable height, and the yeast with strong cohesion is easier to precipitate, while the yeast with poor cohesion needs to use other means to separate the yeast.
(6) Conical bottom tanks are not only suitable for bottom fermentation, but also for top fermentation. Conical bottom fermentation tanks have been used in many breweries to produce wheat beer fermented above.
2. Structure and size
The size of the conical tank was not strictly regulated in the past, the height can reach 40m, and the diameter can exceed 10m. With the continuous improvement of fermentation theory and continuous improvement of brewing technology, in order to meet the requirements of beer quality, the conical tank must be carefully designed and manufactured according to certain specifications. If the height of the conical tank is too large, the convection of the fermentation broth is too strong, and it is easy to form agitation and fermentation. Therefore, the liquid level in the tank is an important parameter, which not only affects the composition of fermentation by-products, but also affects the activity and physiological metabolism of yeast. Tank height and diameter-to-height ratio should be determined according to process requirements. Practice has proved that the highest liquid level of wort in the conical fermentation tank is 5m; the height of the wort liquid level in the conical wine storage tank can be determined according to the actual situation, because the decomposition of diacetyl in the post-ripening process has been completed, which has little impact on fermentation .
3. Production materials and inner wall requirements
The conical tank was originally made of carbon steel plate, but it is easy to rust, so it must be treated with anti-corrosion paint. During use, such large tanks should be checked frequently to prevent the anti-corrosion coating from falling off, and the anti-corrosion coating should be updated regularly. Today's fermentation tanks are mostly made of stainless steel. The smoothness of the inner surface of the conical tank is very important. The inner surface should be as smooth and smooth as possible, and there should be no gaps when inspected with a microscope.
4. Thermal insulation effect
In order to reduce the cost of civil engineering, the conical tanks are mostly placed in the open air. Therefore, the fermenter should be well insulated to reduce the cooling consumption in production. The insulation materials used require low thermal conductivity, low density, low water absorption, and are not easy to burn.
Styrofoam is the best insulation material, but it is more expensive. The price of polyamide resin is relatively cheap, and it can be foamed and sprayed on site, which is convenient for construction, but it is flammable. The insulation thickness of the two materials should be 15~20cm. Expanded perlite is easy to absorb water and has poor thermal insulation performance, but its price is low, and the appropriate thickness is 20~25cm. Of course, the type and thickness of the insulation material also depends on the local temperature and climate conditions. An outer protective layer is required on the outside of the thermal insulation material, which is generally made of aluminum alloy plate or thin stainless steel plate.
5. Pressure performance and safety issues
The conical fermenter must be able to withstand a certain pressure. The temperature and pressure used are different, and the requirements for the wall thickness of the fermenter are also different. Generally speaking, the pressure on the head and the bottom of the cone of the fermenter is greater; the pressure on the lower part of the cylinder is greater than that on the upper part of the cylinder. The parts under high pressure should have high compressive strength, so the thickness of the tank wall should be increased accordingly.
During the use of the conical tank, attention should be paid to the safety of the fermenter to prevent damage to the tank due to overpressure and vacuum. Many breweries are accustomed to using hot water to clean their fermenters or steam to sterilize them, which can be dangerous. Under normal pressure, 1m3 steam weighs 560g, but 1m3 water weighs 1 ton. If the steam is condensed, the steam will shrink to 1/1786 of the original volume. When it shrinks, it will cause a negative pressure phenomenon, which seriously threatens the safety of the tank. In addition, when the feeding speed of the fermentation tank is too fast and the air intake is insufficient; When washing with water, the carbon dioxide in the tank is absorbed by the lye and the volume shrinks. After washing with hot lye and then washing with cold water, the phenomenon of vacuuming the tank is prone to occur. Therefore, it is recommended that the temperature when cleaning the fermenter should not exceed 40°C. Once a vacuum is formed, it will cause damage to the tank. Therefore, positive and negative pressure safety valves should be set according to the requirements of the working pressure.
The above is the relevant knowledge about the fermenter. If you have any needs, please feel free to contact Tiantai!
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