C - like Condenser and Subcooler
What is a condenser?
A condenser is a component, usually made of elemental copper, which is part of the distillation equipment. The condenser is connected to the end of the Lyne arm of the still. The German term for a condenser is Kondensator.
What is the function of a condenser?
The condenser is responsible for re-liquefying the vapors generated by heating the liquid in the stills during distillation.
What does the condenser at St. Kilian look like?
The condenser at St. Kilian has a long, cylindrical shape and is mounted vertically, i.e. upright, at the end of the Lyne arm of the wash still as well as the spirit still. Inside this cylinder are many thin copper tubes arranged in a bundle. As a result, this type of distillation condenser is also called a shell-and-tube condenser. The common name in English is "shell and tube condenser".
How does the condenser work?
Cooling water flows from the bottom to the top through the many small copper tubes in the shell-and-tube condenser. If the distillation vapor enters at the uppermost part of the condenser, it is cooled by the action of the cooling water and liquefies again. The vapor thus condenses on the cooled copper tubes and runs along them on the outside as a liquid film, following gravity down to the exit of the condenser. As a result, the distillate again has long contact with copper (large copper surface), which has an additional cleaning effect and thus leads to a lighter spirit containing fewer sulfur compounds.
What temperature should the spirit be after condensation?
At St. Kilian, we aim for a temperature of the distillate of about 20°C. The reason for this is that we are dealing with flammable alcohols (mainly ethanol) and you can get problems with an explosive atmosphere at a higher temperature. Therefore, the 20°C is authoritative for us to keep. In addition, our alcohol gauge is calibrated to 20°C. If the temperature is too low or too high, it would deliver incorrect readings.
What is a subcooler?
The subcooler at St. Kilian is a plate heat exchanger measuring approximately 40 cm x 30 cm x 15 cm, which is operated by a refrigeration machine and is located behind the condenser.
What is the purpose of the subcooler?
The subcooler serves as an additional cooling source for cooling the distillation vapors and ensures that the temperature of the distillate is maintained at around 20°C.
When is the subcooler used?
Especially in the warm to hot summer months, the ambient temperature in the distillation plant is very high. As a result, we no longer have as much cooling energy in the air and our recooling plant, which supplies the condensers with cooling water, no longer brings up the necessary cooling temperature required for condensation. In this case, the downstream subcoolers ensure that the temperature of the condensed liquid reaches the 20°C mark again.
Is a subcooler always in operation?
No. Because in the cold winter months, we have enough cooling energy in the air and the recooling plant, which supplies the shell and tube condenser with cooling liquid, applies the necessary cooling energy so that the temperature of the condensed liquid is in the desired range.