Cold liquor tank
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In the brewery industry liquor is a term used to refer to water for use in the brewing process. A Cold Liquor Tank is therefore a tank filled with cold process water as seen in breweries. These tanks are often needed because breweries operate as batch production processes rather than continuous processes. This means the production rates of water (liquor) are often insufficient for the point loading requirements of the processes. Cold liquor tanks are used as buffer storage for this purpose such that water production rates are sufficient on average.
The specific use case for a Cold Liquor Tank as opposed to other tanks holding the same quality of water in a brewery is that it holds the water which will be used to cool wort after it has been through the "copper" vessel (a copper vessel is a boiling vessel used to break open complex chains into simpler sugar chains). The wort temperature needs to be reduced to a temperature suitable for yeast to consume the sugars and produce alcohol via the fermentation process.
The cold liquor is referred to as hot liquor after it has been used to cool the wort and is then fed back into the brewing process earlier in the brewery. The hot liquor is stored in hot liquor tanks before usage.
Wort Cooler[edit]
The wort cooler is a heat exchanger used for cooling wort down to a temperature suitable for fermentation and is usually a two stage plate heat exchanger design. These can either use three or four fluids referred to as either secondary or ternary plate heat exchanger systems.
The two stages of the heat exchangers are the initial wort-cold liquor stage and the final wort-refrigerant stage. From cold liquor in the 10-20°C range, the initial stage can create hot liquor in the 80-92°C range which is a useful product stream in an industrial environment. Plate heat exchangers like other heat exchangers are not 100% efficient. The resulting wort from the first stage will therefore not be at the required wort temperature which is also in the 10-20°C range. A secondary stage is therefore needed to trim the wort temperature down to the desired wort temperature. The exact temperatures will vary for a given brewery and a given yeast.
The difference between a secondary and ternary heat exchanger is that a secondary heat exchanger will do the heat transfer between the product and the cooling medium (wort-refrigerant) and a ternary heat exchanger will do the heat transfer using an intermediary fluid (Wort-intermediary-refrigerant). The decision for this is based on the safety and quality control procedures within an individual brewery for a given heat exchanger. This is because the refrigerants used are often poisonous or harmful to humans though there are refrigerants which are safe for human consumption such as high percentage (40-60%) alcohol solutions.
The first stage is ground water and it running back to HLT to next sparge. Glycol serves as a secondary cooling system and its back to glycol container. Valves on both channels, and a temp exploration right after the heat exchanger. Heats up your water for your next brew without using any extra power, reuses your water you would use from a CLT, and saves you the space of a whole tank.
Water (liquor) quality[edit]
The quality of the water used for this application in cold liquor tanks can differ drastically between breweries across the world.
The volumes of water involved often require a large supply of water which will dictate the source of water. Typically this will be ground water drawn up from below the brewery though it might also be a river water source where this is not a viable solution. A public utility water supply might also be one source though often chemicals are added which can present a challenge to its usage.
Depending on the source of the water it will go through different processes to make it suitable for use. This can involve filtration systems like membrane filtration which can produce water too pure for the process. If this is the case often additives will be added back into the water to produce an environment suitable for good yeast propagation or for a desirable taste in the finished product.
A town in the United Kingdom called Burton-upon-Trent has ground water which was known to produce good flavoured beers and as such the term "Burtonification" has been used to describe the process of producing water to a similar quality as the ground water of the town. This is only one example of a water quality target that might be used by an individual brewery for their desired flavour profile in the end product.
Primary purpose of the CLT’s[edit]
Because of the batch nature of brewing processes it would be costly to purchase equipment which can make water at the rate of point usage in comparison to making suitable water continuously at a lower rate which is a sufficient overall volume for the usage when it is needed. One aspect that helps with this assessment is that there are other processes in a brewery which require water. One such process is blending high concentration beer down to the sales concentration after it has been filtered. If all of these point uses were to coincide the required production would be at significant excess to the possible production rate. For this reason there are buffer tanks throughout a brewery at different qualities for different purposes. The DeAerated Water (DAW) or DeAerated Liquor (DAL) tank is another example of this and all of these tanks combined help to level out the water production demand.
Temperature[edit]
The storage temperature and usage of the hot liquor tanks is something which is an important balance within a brewery. This is particularly the case where the brewery does not operated 24/7. Many breweries operate 24/6 or some other variation which leaves the generated hot liquor to sit and cool down over the period of plant downtime. This reduction in temperature can cause the brewhouse to struggle when starting back up as they try to reach the desired temperatures. For this reason the temperature recovery within the system is an important and well monitored condition of the brewery. Steam coils within the hot liquor tank can be used to maintain the temperature during downtimes. Other methods of maintaining the temperature are recirculation loops through steam plate heat exchangers. Hot liquor tanks are often double skinned insulated vessels.
The temperature of the cold liquor tank is the other side of this equation where the temperature being higher is bad for the heat exchanger efficiency but good for the overall temperature of hot liquor generated within the wort cooler. Keeping the tanks cool also helps to reduce the refrigerant usage as the wort can be lowered to a temperature closer to the required temperature for the yeast with just the cold liquor. Typically a brewery will prefer the lower temperature cold liquor as refrigeration costs can be quite high. To achieve this cold liquor tanks are usually placed in cold areas of the plant away from heat generating equipment. Cold liquor tanks are typically single skinned vessels with no insulation.
Frequency level of the cooling capacity of the beer helps to recommend the appropriate volume and cooling methods. It can contain 1000+ litre and when water can be passed through the heat exchanger and when it run hot liquid tank temperature near about 70 to 80-degree Celsius. It's a typical process and its help continuous brewing without any break and no need waiting for gain actual temperature.
Features of cold liquor tanks[edit]
- 12 Gauge 304L Stainless Steel Construction
- Double Walled and Insulated
- 1 1/2" Polyurethane Lining
- Internal Welds Ground to a Healthful Food Grade Finish
- Exterior Polished to #4 Brushed Finish
- Flat Bottom with 1 1/2" TC Center Drain
- Dome Top with 18" Round Manway
- 1 1/2" TC Water Inlet Port
- 1 1/2" TC Water Return Port
- 1 1/2" TC Temperature Port
- Removable Level Gauge
- Water Re-Circulation Assembly
Sizes of CLT’s[edit]
There are several sizes of CLT's and HLT's for commercial use purpose but the size of the tanks totally depends on the production and brewing system with water at the quantity and temperature needed. 2.5x is the proper size of CLT's.SW = Single Wall,J/I = Jacketed and Insulated,
- 4 bbl (SW) (J/I)
- 5 bbl (SW) (J/I)
- 7 bbl (SW) (J/I)
- 10 bbl (SW) (J/I)
- 15 bbl (J/I)
- 20 bbl (J/I)
- 30 bbl (J/I)
Automation of the CLT’s[edit]
All tanks remain consistent with stainless steel piping and automated valves the brewer can only recirculate, radiation or pass it to the brewhouse without transmitting the platform. Put the tanks in “auto” mode and they are at temp when they hit the brewery!