Monitoring moisture on the inlet to an ozone generator

Measurements that matter.

Summary:

Ozone is a common disinfectant in water and wastewater treatment plants. Ozone generators are used to produce the ozone on-site. Moisture measurement is a key measurement in the oxygen fed into the ozone generator.

Application:

Ozone generators convert oxygen from either an air source or a pure oxygen source into ozone. This is done by applying a large amount of power to the system. The presence of moisture can cause arcing or sparking in the ozone generator, which is detrimental to the operation and health of the generator.

The source gas is expected to be dry going into the generator; but, leaks in the system can allow ambient moisture to enter. Monitoring for moisture is the proper preventative maintenance.

Solution:

The choice of moisture analyzer technology is based on the customer need. A simple aluminum oxide moisture analyzer is ideal, as it can monitor the moisture content from ambient down to the low ppm values of moisture typically found in these applications. These systems can be provided cleaned for oxygen service with little difficulty and at little expense to the customer. An annual calibration at the vendor’s nearest calibration facility ensures that the sensor is providing accurate measurements. Having a spare sensor on hand is inexpensive and allows for verification when readings appear higher than expected.

The moisture measurement system is comprised of an aluminum oxide sensor mounted in a sample system that draws a small amount of the oxygen past the sensor. The display package drives the measurement and can be equipped with alarm contacts to help indicate an alarm condition. The analog output can provide a constant reading back to the control room.

Tunable diode laser hygrometers may be used, but at a higher base expense. Providing these cleaned for oxygen service will also increase the total up-front purchase price. Savings can be realized over the life of the analyzer, as no regular maintenance of calibration is required.

It is critical to quality to choose a manufacturer who has decades’ experience with recommending and providing the appropriate technology and with sample system design. Choosing the appropriate materials and providing a complete package ensures analyzer performance and minimizes uncertainty in the measurement integrity.