Ozone water treatment systems convert the oxygen in air or other feed gas into ozone and mixed it with water for the specific water treatment applications, e.g. disifection. Many applications are critical and reliability is important in the design of these systems.
There are a number of factors that can cause these an ozone water treatment system to fail. This article tries to group them into six basic categories based on my ten years of experience building and servicing this type of system. The typical failure mechanisms include:
• Back Flow of Water into the Generator
• Poor Feed Gas Quality
• Under sizing the system for the application
• Poor ozone transfer efficiency
• Ozone generator cooling issues
• Incorrect materials of construction
We will briefly discuss each here.
Back flow of water is possible since many application call for injecting ozone into a water system with higher pressure than the ozone generator, as a result, under the right conditions, water could flow into the generator. Because of the nature of the generator, this would result in sever damage and significant repair time. Well designed systems employ multiple barriers to prevent this condition including both passive devices and active controls.
The ozone generator requires a clean dry source of oxygen or air. Failure to deliver a high quality gas feed will result in both damage to the generator and a reduction in generator efficiency. Well designed systems employ gas dryers, filters and instruments to monitor gas quality with interlocks to shut down the system if poor gas quality is discovered.
If the ozone system is under designed, it will not have sufficient capacity to meet the requirements of the application. The sizing of the system will require laboratory and pilot studies prior to committing to a system size. It is usually not possible to predict without such studies the proper size of an ozone water treatment system.
Another design factor that must be considered is the efficiency of dissolving ozone into water for a given system. Only ozone that dissolves into water is useful for treatment. Since ozone has limited solubility in water, it is important to design the system to achieve a high degree of efficiency, normally greater than 90%. Well designed pilot studies can confirm the expected transfer efficiency.
Ozone generator output is a function of operating temperature. Whether cooled by water or air, the generator capacity declines with increasing cooling medium temperature. So, the design of the system must take into account ambient conditions on site.
The final area where problems occur is materials of construction. Ozone is a strong oxidizer and can damage materials not appropriate for the application. The incorrect materials will result in leaks and failure of various down stream equipment.
During the design or purchase of an ozone water treatment system, each of these factors should be carefully considered.
For more information on ozone water treatment system design visit www.SpartanWaterTreatment.com of contact us at info@spartanwatertreatment.com.