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Closed Cooling Systems and their Challenges
More and more we receive inquiries regarding Closed Cooling Systems. This refers to a closed loop for the water used during cooling to minimize water use. The reasons for these requests and wish to minimize water use are varied, but can be for economic reasons (to save money), for ecological reasons (environmental awareness) or practical reasons (a local water shortage).
Before we discuss the systems and their challenges, let us first look at what is required of a cooling system.
Why do we need a Cooling System in a Distillery?
During distillation, energy is added to a mash in the form of heat, thereby bringing the mash to a boil, causing rapid evaporation, so the separation of the different components within the fermentation can be accomplished. However to return these vapors to a liquid form, condensation, the energy that was added to the fermentation needs to be removed through cooling. This is done through the use of cold water which absorbs the energy from the hot vapors, and with the energy removed, it returns to a liquid state.
As the cold water absorbs the energy from the vapors it heats up, and if the temperature increases too much, it will no longer be able to absorb energy from the vapors, therefore the cold water needs to flow continuously to carry away the absorbed heat and allow condensation of all the vapors. Failure to condense the vapors fully will result not only in a loss of alcohol, but can be dangerous as these vapors are not only flammable, but explosive as well.
How much Water does a Still use during a Distillation Run?
A continuous flow of water through even a small alembic still can add up quite quickly to tens if not hundreds of liters of water. (i.e. a 1000 lt tank will easily heat to 50 degrees Celsius during a 100 liter distilling run). Plate Column Stills which require continuous water flow through both the main reflux and spirit condenser uses even more water. Up to a couple of thousand liters during a 5 to 6 hour spirit run on a large still. Cooling systems can also be expanded to include cooling for fermentation containers.
How do I make a Closed Loop Cooling System?
Let us say we want to create a closed loop system for a 100 liter Plate Column Still. We take a 3000 lt Plastic JoJo Tank and using a small pump we circulate the water from the tank through the main reflux and spirit condenser. On such a volume we should be able to cool an entire run, but all the water in the tank will have heated up, and can take up to 6 or 7 days to lose the transferred heat. This means that if we were to use this method to cool our still, we would only be able to distill once every week.
For a commercial operation, this is not practical.
To cool the water in the closed system we therefore need to use a condenser or chiller unit (which can be quite expensive – tens of thousands of Rands), or multiple water tanks (which will also be expensive and take up more floor space).
How do Home Distillers Cool their Stills?
Smaller distillers or Home distillers have come up with some innovative solutions to this problem, for instance using a swimming pool as cooling water reservoir. The large volume and larger surface area for heat exchange allows rapid heat transfer, with the added benefit of heating your swimming pool for no additional cost.
For the very small scale Home distiller using a 5 or 10 lt Alembic still, a 200 lt plastic barrel of water can be used, along with an aquarium pump. For more effective cooling, empty 2 lt plastic bottles filled with water can be frozen and placed in the water inside the barrel to make the system more efficient.
Keep on Distilling !!!