The Ozmotics Insider

Corona discharge ozone generators typically fall into the two categories ( based on the feed gas used to generate the ozone). While some require purified oxygen, others claim to be able to operate using an ambient air feed. What are the main differences between the two and which one is the right choice for you?

Oxygen Fed Ozone Generators:

Oxygen fed ozone generators typically require an additional component called the oxygen concentrator.

The ambient atmospheric air is composed of approximately 78% nitrogen, 21% oxygen, 0.9% argon and the rest being the trace amounts of elements such as hydrogen, helium, etc. By removing the nitrogen from the air and feeding the pure oxygen (typically about 95% purity), the ozone generator is capable of producing more ozone using the same gas feed throughput compared  to ambient air fed generators.

Ambient Air Fed Ozone Generators:

The advantage of the ambient air fed ozone generators is that they are smaller, less complex and more portable. Because they do not need the oxygen concentrator as a major component, they are also cheaper to manufacture. But there are also several shortfalls of the ambient air fed ozone generator in addition to the efficiency. These include maintenance considerations and humidity.

Maintenance Considerations:

Since ambient air fed ozone generators intake air that is composed of 78% nitrogen, there is no way to stop the formation of the nitrogen oxide byproduct that will deposit on the surfaces inside the generators (corona plates, etc.). Therefore ambient fed ozone generators require much higher degrees of maintenance which in most cases involve fairly complex procedures such as tearing down your ozone generator to clean the corona plates.

While some people are OK with this shortfall, others prefer a more maintenance-free approach. Depending on how you feel about tearing down your ozone generator and re-assembling it, you may or may not want to look at purchasing the ambient air fed ozone generator.

There may also be some health hazards associated with the cleaning process of the nitrous oxides inside the ozone generators since the nitrous oxides are known to react with the water forming the highly corrosive nitric acid. Therefore the appropriate protective wear is highly recommended when servicing or cleaning the nitrogen oxide deposits inside your ozone generator.

Humidity:

Ambient air fed ozone generators must be fed with relatively dry air. The nitrous oxide dissolves in water to form nitric acid. Nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid that can cause severe burns (source: http://en.wikipedia.org/wiki/Nitric_acid ). Therefore the humidity must be eliminated from the feed air before it enters the ozone generator.

The air dryer is usually incorporated into the oxygen concentrator design so in most cases you do not need to worry about having it if you are using the oxygen fed ozone generator.

Conclusion:

While air fed ozone generators are typically less expensive they require a lot more maintenance than the oxygen fed ozone generators. However because of the extra added oxygen concentrator unit, the oxygen fed ozone generators are typically larger, bulkier and more expensive to initially purchase.

Selecting the proper model and proper technology would require understanding the application where the ozone generator will be installed, inherent health risks associated with the technology as well as maintenance preferences of the end-user and operator that will be using the technology.

A proper research and planning is usually recommended before deciding which unit and what technology to select and purchase.

In order to yield the higher volume ozone output typically required for the industrial ozone applications, your ozone generator must be designed to accept a gas feed containing a significantly higher concentration of oxygen than what is readily available om the ambient air.

Since the typical composition of ambient air is 21% oxygen and 78% nitrogen, the most economical way to increase the concentration of oxygen in ambient air is to remove the nitrogen component from it.

As a side benefit of removing the nitrogen from the ozone generator gas feed source, the nitrogen oxide and the nitric acid byproduct is also removed effectively reducing the amount of maintenance and scheduled service work typically required to remove such byproducts from inside the ozone generator corona discharge chambers.

The Pressure Swing Adsorption (PSA) Process

The Pressure Swing Absorption (PSA) Process

The PSA oxygen process uses a special material called zeolite to remove the nitrogen from the ambient air. Zeolite is used as it absorbs the nitrogen when subjected to a high pressure while releasing the absorbed nitrogen when the pressure drops.

The PSA process works by feeding the ambient air into a pressurized chamber containing zeolite. The nitrogen is absorbed by the zeolite while the oxygen is further passed through to the storage tank. When the zeolite is saturated where it can no longer effectively absorb the nitrogen, the chamber is depressurized. When the chamber is in the depressurized state, the nitrogen is released by the zeolite medium and vacates the system. The chamber is than re-pressurized and the cycle is repeated over and over generating purified oxygen for the oxygen fed ozone generator or any other application requiring the high purity oxygen gas feed.

Because of this simple design principle the PSA generators require very little maintenance and as such are a favorite choice for the on-site commercial and industrial oxygen purification process (the oxygen is purified on-site versus transported from outside in bottles therefore lowering the total operating cost of the process).

PSA Oxygen Concentrators and Ozone Generators

PSA Oxygen Concentrators usually go hand-in-hand with any ozone generator application where the gas feed is oxygen and not ambient air.

The output of the PSA oxygen generator is measured in the SCFH (standard cubic feet per hour). While the overall principle remains the same for all manufacturers, different manufacturers will use different designs resulting in different footprints as well as different capacities from one manufacturer to another as well as from one model to another.

To select a proper oxygen concentrator for your ozone generator application you will need to know the requirements of your ozone generator. It is typically recommended that you size your oxygen concentrator slightly larger than the current intake requirement of your ozone generator. While ozone generators can be engineered to be expandable (modular design, simply add extra ozone generator unit to your application), expanding the production capacity of the oxygen concentrator is a much harder task to accomplish and usually requires replacing the entire oxygen concentrator assembly.

If you have an application that requires an oxygen concentrator and need help sizing a unit please contact our Ozmotics representative at 1-877-386-3763.