Information about air dryers for ozone generatorss
Drying the supply air from an ozone generator is often seen as optional, when it is actually a necessity. Contrary to popular belief, dry air must flow through the ozone generator at all times, both when it is turned on and when it is turned off!! The latter is often forgotten.
Effect of moisture on ozone generation
Most people are aware that nitric acid is formed in an ozone generator when the supply air contains moisture. This only happens when the ozone generator is switched on. The moment the ozone generator is switched off, something else happens that is just as harmful. The moisture present in the air will condense inside of the ozone cell, making it moist and sticky. Dust and dirt particles in the air will then stick to the ozone cell. The second the ozone generator is switched on, the ozone cell heats up, then the pollution is practically baked into the ozone cell. The nitric acid that is formed when the generator is switched on again will then mix with this layer. The result is that the inside of the ozone cell is “coated” with a very aggressive layer of chemicals, which strongly damages the cell.
Manual air dryers
The most simple air dryers consist of a tube filled with silica gel. These dryers are widely used in the hobby sector. These dryers can work just fine if they are properly maintained. The maintenance interval usually varies from a few days to a few weeks at most. The maintenance interval is mainly determined by the amount of moisture in the air and by the type of silica gel that is used. There are many variants of silica gel available, each with specific properties, the most important of which is the dew point reduction. Industrial silica can achieve a dew point drop of -70°C. The cheap varieties achieve a dew point reduction of -10°C at most. You may wonder what this means in practice. For a high ozone yield and low maintenance it is important to achieve the lowest possible dew point. With a manual dryer, this has the disadvantage that the dryer requires a lot of maintenance. A 500 gram dryer with industrial silica will saturate much faster than the same dryer with cheap silica. After all, the cheap variant absorbs much less moisture from the passing air. Using a dryer filled with cheap silica reduces the formation of an aggressive deposit in the ozone cell. However, it has little influence on the ozone yield. To achieve a higher ozone yield, good quality silica will have to be used. In practice, this is often not workable due to the very high maintenance interval.
Advantages:
- Easy
- Cheap
Cons:
- A lot of maintenance
- Does not affect the ozone yield
- The drying granules often contain a lot of dust, which ends up in the ozone generator
Automatic air dryers
Automatic air dryers are available, the so-called automatically regenerating dryers. These dryers consist of 2 tubes filled with a desiccant. Air is drawn in through 1 of these tubes and pumped through the ozone generator. Over time, the desiccant will be saturated. At this point, the dryer switches to the other tube. The saturated tube is now heated, expelling the moisture from the desiccant. This process is continuously repeated. These dryers require little/no maintenance and can reach a dew point of -40°C depending on the model. Unfortunately, these dryers are quite expensive. However, it does provide a higher ozone yield and much less maintenance on the ozone generator.
Advantages:
- Dry air
- No/hardly maintenance
Cons:
- Relatively expensive
- Usually consumes as much energy as the ozone generator
Which air dryer is applicable in my situation
In general you can say that the manual dryer is only suitable for the hobby market. In all other situations an automatically regenerating dryer or an oxygen concentrator is a better alternative.
Air treatment
When treating large spaces with ozone, special ozone generators intended to use for large volumes are used. It is not possible to use a dryer with these ozone generators. When introducing ozone into air handling units, it is possible to work with ozone generators equipped with a dryer. Only an automatically regenerating dryer is applicable here.
Ponds and swimming pools
For ponds and private swimming pools, a manual dryer is a reasonable choice, an automatic dryer is a better alternative for a more discerning user.
Public swimming pools, zoos and amusement parks
In this industry, an oxygen concentrator is almost always the best choice. The only exception is a(relatively) small swimming pool, where an automatically regenerating dryer can sometimes be used.
Industry
The best choice is an oxygen concentrator with a matching ozone generator.
© Tol Watertechniek