C – for Condenser and Subcooler

What is a condenser?

A condenser is a component, usually made of elemental copper, which is part of the distillation plant. The condenser is connected to the end of the still's lyne arm. The German term for a condenser is Kondensator.

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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 vertically attached to the end of the lyne arm of both the wash and spirit stills. Inside this cylinder are many thin copper tubes arranged in a bundle. This type of distillation cooler is therefore also called a shell and tube condenser.

How does the condenser work?

Cooling water flows from bottom to top through the many small copper pipes in the shell and tube condenser. When the distillation vapor enters the uppermost part of the condenser, it is cooled by the effect of the cooling water and re-liquefied. The vapor thus condenses on the cooled copper pipes and flows down them as a liquid film, following gravity, to the outlet of the condenser. This means that the distillate has prolonged contact with copper (large copper surface), which has an additional purifying effect and thus leads to a lighter spirit containing fewer sulfur compounds.

What temperature should the spirit have after condensation?

At St. Kilian, we aim for a distillate temperature of about 20°C. The reason for this is that we are dealing with flammable alcohols (mainly ethanol) and a higher temperature can lead to problems with an explosive atmosphere. Therefore, 20°C is crucial for us to maintain. In addition, our alcohol hydrometer is calibrated to 20°C. This would provide incorrect readings at temperatures that are too low or too high.

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 unit and is installed 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 distillate temperature of approximately 20°C is maintained.

When is the subcooler used?

Especially in the warm to hot summer months, the ambient temperature in the distillation plant is very high. This means we don't have as much cooling energy in the air, and our recooling unit, which supplies the condensers with cooling water, no longer provides the necessary cooling temperature 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 unit, which supplies the shell and tube condenser with cooling liquid, provides the necessary cooling energy so that the temperature of the condensed liquid is within the desired range.