Distillation is the process of heating a mixture of two or more components to a temperature between their boiling points in order to separate it into its original state.
For example, at atmospheric pressure, water boils at 212°F, while ethanol boils at approximately 176°F. If a mixture of water and ethanol is heated to around 195°F, the ethanol will boil and turn into steam, which can then be collected and condensed. The water will separate and remain in liquid form.
In order to obtain alcohol with the desired flavor and aroma, spirits must undergo distillation to separate the alcohol and water in the fermentation broth. This is achieved through the use of a device called a still. There are two types of stills:
Pot Distillers/Potstill Distillators
A pot distiller, also known as a potstill distillator, is typically made of copper. Copper is traditionally used because it is a good conductor of heat and can remove sulfur from the distillate. The classic pot still consists of various components, with the bottom portion called the kettle where the fermentation broth is heated. The broth evaporates, and the steam travels through the swan-shaped neck to reach the worm, which is a spiral copper tube connected to the condenser where the steam is condensed back into a liquid form.
Typically, aged spirits such as whiskey, tequila, and rum, as well as craft spirits, are produced using a pot still. The pot still also helps to add congeners to the spirits, creating aromas and flavors.
Modern pot stills are descendants of early distillation devices.
One notable example is the historic whiskey pot distiller at Jameson Middleton Distillery in Cork, Ireland.
The largest pot still ever used is located in the Old Middleton Winery in County Cork, Ireland. Built in 1825, it has a capacity of 143,740 liters (31,618 British gallons), but is no longer in use. As of 2014, the largest pot still currently in use is situated at the neighboring New Middleton Distillery in County Cork, Ireland, with a capacity of 75,000 liters (16,000 British gallons).
Components of a Traditional Pot Still:
The components of a traditional pot still include:
- Pot – where the wash is heated
- Swan neck – where steam rises and flows back
- Lyne Arm – transfers steam to the condenser
- Condenser – cools steam to produce distillate
The materials used for pot stills are stainless steel or red copper for the pot body, copper for the swan neck, and copper for all parts that come into direct contact with the wine.
Column Distillers/Shelf Distillers
Column distillers, also known as shelf distillers or continuous distillers, are a relatively modern design used for extracting pure alcohol directly from fermentation. They are commonly used in industrial and large-scale commercial alcohol production.
A column distiller is made of stainless steel or copper and features a tall column structure connected to the top of the boiling kettle, allowing for the extraction of purer steam. Perforated plates are used to divide the column into multiple chambers. The distiller is constantly heated at the bottom, so when the fermentation broth is poured from the cooler top and encounters steam, it evaporates and sends the alcohol back to the top. As the alcohol-carrying vapor passes through the perforated plate, it condenses the heavier particles. Only the alcohol-carrying vapor continues to rise to the top and passes through the pipe connected to the condenser, where it is condensed into the desired liquid.
Within the column, as the liquid flows down, the steam comes into contact with it multiple times, facilitating the key process of component separation. This is due to the conversion of molecules between the gas phase and liquid phase, driven by energy release and the use of free energy.
Column distillers are used to extract white or neutral spirits, such as vodka, gin, and white rum.
Main Components of a Column Distiller
A column distiller consists of several components, each serving a specific purpose in heat transfer or material separation:
- Vertical housing for separation of liquid components
- Tower internal components, such as trays/plates and/or packing to enhance component separation
- Reboiler, which provides the necessary vaporization for the distillation process
- Condenser, used to cool and condense the steam leaving the top of the tower
- Reflux tank, which contains the condensed vapor from the top of the tower, allowing the liquid (reflux) to be recycled back into the tower
The materials used for column distillers are stainless steel or red copper for the pot body, copper for the swan neck, and copper for the distillation column. All parts that come into direct contact with the wine are made of copper.
Pot Distillers vs. Column Distillers: Differences in Material
The two main types of materials used in constructing pot stills and column stills are copper and stainless steel. The majority of distillers today are made from one of these materials, so the choice ultimately comes down to personal preference. It should be noted that while most pot stills are entirely made of copper, column stills can sometimes have a stainless steel lower portion with a copper upper portion, as copper has the important property of removing sulfur from the spirit.
While stainless steel distillers are durable, easy to clean, and less expensive than copper distillers, they do not conduct heat as well and do not remove sulfides from the wash. Sulfur is naturally produced during the fermentation process and can result in an unpleasant taste. Therefore, it is preferable to remove it.
This is where copper shines. Copper is more popular than stainless steel for several reasons and has been the preferred choice for still construction for centuries. One major advantage is its ability to improve the flavor of alcohol by removing sulfur during distillation. Copper also aids in breaking down compounds that are crucial for producing high-quality, flavorful spirits. Additionally, copper is an excellent conductor of heat, further enhancing its superiority over stainless steel.
It is difficult to determine which type of still is better. The choice between a pot still and a column still depends on individual needs. If you are uncertain, you can consult us, and we will do our best to provide you with guidance based on your requirements.
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