Air treatment refers to the equipment and processes used to clean up compressed air to make it suitable for whatever application it is being used in. In all breweries, from startup nano sized up to major production breweries, clean and dry air is needed. The typical uses of compressed air around a brewery falls into these categories:
- Keg washing
- Canning/bottling lines
- Pneumatic controls on a brewhouse
- Sterile air for yeast brink agitation
- General shop air around the brewery
For most of these uses clean, dry air is a must. But what do we actually mean when we say clean and dry air?
When air leaves the compressor, it is typically hot and saturated with condensate. How hot and how saturated will depend on the compressor making the air (check our previous blog post here about different types of compressors). We’ll first discuss drying the air and then we’ll talk about cleaning it up.
Compressed Air Dryers
There are a number of different types of compressed air dryers available but the ones most commonly found in breweries are refrigerated dryers. These use a refrigeration circuit to cool the air down and get it to around a 38°F dewpoint. This means that down to that temperature, no more water will condense out of the air. Lower than 38°F and you will see condensation. Since most breweries keep their room temperature above that, this should be adequate.
There are three different types of refrigerated dryer available:
- Non cycling refrigerated dryer
- Cycling Refrigerated Dryer
- High Inlet Temperature Refrigerated Dryer
Non cycling dryers will run all the time, constantly cooling the air. These are the least expensive kind of dryer but less energy efficient than a cycling dryer. A cycling dryer will cool a thermal mass inside the dryer and then switch off, relying on the cooled mass to cool the air as it passes over it. They save energy on cooling but you will see dewpoint swings as the mass warms up and then is cooled down again.
A high inlet temperature dryer is used when the compressor making the air does not have any aftercooler. You typically see this on piston compressors and due to the lack of aftercooler the air entering the dryer is at a much higher temperature than is appropriate for a standard refrigerated dryer (>150°F). These dryers have an aftercooler built into them and will take that hot air and cool it down before it gets to the refrigeration circuit.
Why is dry air important?
When air is saturated with condensate it can lead to trouble down the line. Your keg washer sensors can fail, it can cause issues with your canning and bottling line, and dirty air should never be used to purge your keg after a washing cycle. For the longevity of your equipment and for overall cleanliness and sanitation, you really should use dry air around the brewery.