The Ozmotics Insider

Many configurations had been developed and tried and there may be further variations in the design of a turn-key ozone injection skid but in general the principle is fairly similar. Here we will attempt to outline the major components of the system.

Ozone injection skid – The process explained:

Step 1 – The Air Dryer

Using the corona discharge ozone generator and the oxygen concentrator (oxygen fed  ozone generator), the ozone injection skid typically follows the line process by which the ambient air is first circulated through the air dryer (the ambient air must be sufficiently dry and free of moisture in order to be used as a feed for the oxygen concentrator).

Step 2 – The Oxygen Concentrator

The Pressure Swing Adsorption (PSA) oxygen concentrator is commonly used to generate the high concentration oxygen feed that is required for the production of the ozone. To learn more about the pressure swing adsorption principle and understand how the PSA concentrator is used to efficiently and economically purify and concentrate the oxygen from the ambient air we invite you to read this article:

http://www.ozmoticsinsider.com/2008/10/pressure-swing-adsorption-psa-%e2%80%93-the-typical-layout-of-the-psa-oxygen-concentrator/

It is recommended to plan for the future and always install the larger oxygen concentrator unit than the immediate demand of the ozone generator equipment. While with some insightful planning and design (building a modular rack that can hold multiple ozone generator units) one can make the system expandable for the future growth and demand if the oxygen concentrator cannot produce enough oxygen gas feed as required by the expanded system, the entire concentrator will need to be replaced. Therefore it is always better to plan for a larger oxygen concentrator unit than what the immediate ozone generator input requirement directs.

Step 3- The Ozone Generator

The corona discharge generator is typically recommended for higher capacity ozone production since it can produce more ozone at a higher concentration compared to UV ozone generators. The corona discharge ozone generator is also typically smaller and more compact therefore more practical to use in the engineering design of an ozone injection skid.

The modular design is highly recommended for the planning and integration of the ozone generator meaning that multiple smaller capacity ozone generator units are preferred over a single larger capacity ozone generator unit.

By installing high quality ozone generators in multiple unit configurations, even if the single ozone generator cell is to fail, the other cells will still continue generating the ozone therefore allowing for the uninterrupted and continued ozonation operation.

Step 4 – Static Mixer and Venturi Injector

The efficiency of ozone to react with the water or other intended substance is strongly correlated with the contact area between the ozone and the substance you’re treating.

For aqueous ozone injecting applications (injecting the ozone in water or other liquid solutions), two methods are commonly used. The first method using an air stone diffuser will generate larger ozone gas bubbles therefore decreasing the available contact area of ozone to water. As such an air diffuser is not recommended in the design of the ozone injection system.

The Venturi injector is capable of diffusing the ozone gas as a much smaller bubbles therefore cumulatively increasing the contact area of ozone to the water or other liquid medium where ozone is to be injected. As such more ozone is used in the process and less residual ozone ends up escaping the system therefore lowering the production demand as well as the size of the ozone destruct equipment (used to destroy any escaped ozone from the contact chamber).

Step 5 – Contact tank

The ozone is typically mixed with water in a higher concentration than required (concentrated mix) and let to dissolve inside a contact tank. The contact tank will usually be designed with the obstacles (baffle) to allow the water to flow longer inside the tank before it exits and therefore allowing higher concentration of ozone to be dissolved in the water or other liquid used as the solvent.

Step 6 – Ozone destruct unit

Ozone destruct unit is used to destroy any unused ozone escaping from the contact tank. The destruct unit is usually a chamber in which a catalyst is packed (a catalyst will help break out ozone back into the oxygen before it is vacated to the outside of the contact tank. To ensure that no moisture enters the catalyst chamber, a water trap is typically installed in between the contact tank and the ozone destruct unit (to trap and collect any moisture escaping from the contact tank.

Step 7 – Ozone mixing chamber

The ozone mixing chamber is typically an external tank where the untreated water is mixed with the water from the smaller contact tank (where the higher than required concentration of ozone is dissolved to create a concentrated mix of water and ozone).

By mixing the high concentration of the dissolved ozone from the contact tank with the untreated water the diluted equilibrium of the desired ozone concentration is achieved in the entire body of the water (or other liquid to be ozonated). By increasing or decreasing the flow of water from the contact tank, the concentration of the ozone in the mixing chamber can be achieved.

Step 8 – Ozone Injection Skid Architecture Design (Conclusion)

This two step approach (ozonating only the part of the entire flow to a higher concentration and than mixing the high concentration of the ozonated liquid with the main body of the liquid to be treated), is far more economical than utilizing the single step inline ozonation where the entire body of the water (or other liquid to be ozonated) is ozonated. By requiring to ozonate only a portion of the flow to be treated, the size and capacity of the infrastructure (pumps needed to maintain the flow and pressure, injectors, pipes carrying liquid, etc.) is greatly reduced while still being able to treat the entire flow in general. The savings in the material are complimented by the savings in the real estate needed to install the ozone injection equipment (much smaller skids comparing to the similar capacity inline ozone injection skids).

The description offered in this article is a simplified description of the principle used to inject the ozone into the water or other liquids to be treated. The complete turn-key ozone injection skid has many more components than what has been explained in this article. Pumps, dissolved ozone monitoring probes, ORP meter, safety monitoring probes (to detect any accidental leak of ozone out of the skid, etc. can be further found inside the engineered turn-key ozone injection skid.

If you require additional information on the engineering and design of the turn-key ozone injection skid or need help sizing a unit please contact your Ozmotics representative at 1-877-386-3763.

BTEX is a common acronym used to describe benzene, toluene ethyl benzene, and xylenes. BTEX compounds are some of the most commonly VOC (volatile organic compounds) found in petroleum derivatives such as gasoline and are often found as a persistent contaminants in the areas prone to gasoline and gasoline derivative spills (old gas stations, gasoline storage yards, refineries, etc.).

The inherent danger of BTEX is that toluene, ethyl benzene, and xylenes are very toxic substances with the documented history of harmful effects on the central nervous system. Because of the solubility of the majority of the BTEX components they are also prone to leaching into the underground waterways therefore polluting much wider area than the original contamination site. As such the decontamination of soils and ground water contaminated with the BTEX traces is strongly recommended.

Ozone is well known oxidizer able to decompose most of the complex organic substances to the less harmful basic elements from which the complex substance is derived. In case of the BTEX, this is the hydrogen and carbon. Through further reaction the hydrogen is used to create water and the carbon is either left in its pure state or further synthesized in carbon dioxide.

In-Situ soil and ground water remediation – Ozone Sparging.

In-situ ozonation of the BTEX contaminated soil and ground water has shown promising results in removing BTEX without the need to remove the contaminated soil for off-site remediation. Also referred to as “ozone sparging” the technology involves injecting the ozone deep inside the contaminated ground where it comes into the contact with the BTEX contaminants therefore starting the process of the decomposition.

In documented research studies and reviews of the data from projects where the ozone sparging has been successfully used for the soil and water remediation, the contamination of BTEX in the soil and surrounding ground water has been successfully reduced by as much as 90% within the first five weeks of the treatment and as much as 98% + reduced by the week seven or eight of the treatment.

Ozone for soil and ground water remediation – Conclusion.

Because the soil does not have to be removed or decontaminated off-site and because the ozone leaves virtually no byproduct traces (unlike chemical treatment), the in-situ ozone sparging is both an economical (saves money) and effective solution (98% or higher contaminant removal rate) for soil and ground water remediation of sites contaminated with the BTEX and other petroleum derivatives).

Therefore the in-situ ozone sparging is highly recommended in treatment of the BTEX and petrol derivative contaminated soil and ground water.

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

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 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.