optical dissolved oxygen technology

Better Optical DO Technology Reduces Power Plant Corrosion

In a power plant, it is essential to take control of dissolved oxygen (DO) to reduce corrosion levels and the resulting deposits of metal oxide corrosion in critical components. Measuring DO in power plants requires high-performing, reliable optical sensors to achieve successful management.

Strategies to Manage DO

Reducing and oxidizing are the two basic feedwater chemistry strategies used for managing DO in power plants.

Reducing conditions is the preferred strategy where copper alloys are in the feedwater. Technicians choose this strategy when they can’t maintain a high level of feedwater quality.

Oxidation is an option in situations where you have high-quality feedwater composed entirely of ferrous alloys.

Reduction is the right option when feedwater is poor quality and/or copper is detected. This strategy uses a combination of deaeration and a reducing agent such as hydrazine to lower the DO content. The result is a protective cuprous oxide layer over the copper alloy.

With lower DO levels, accuracy and reliability become critical considerations for managing the reducing feed agent feed. If the DO measurements are inaccurate, technicians may add too much reducing agent, and the situation would prove costly and wasteful. Adding too much reducing agent can produce conditions leading to accelerated corrosion and complete failure. Oxidation-reduction potential measurement is the right solution to monitor excessively reducing conditions in the power plant.
There are definite advantages to implementing oxidization for managing DO for power plants with all-ferrous feedwater. No reducing agent is needed. In addition, the mildly oxidized conditions are suitable for developing red ferric oxide hydrate over the blued steel magnetite layer. This combination results in a highly-durable, corrosion-resistant surface.

Optical Sensor Technology for PPB Levels

Design and measurement principle of the Pure Water Optical DO Sensor
Optical sensor technology for DO sensors was first introduced about 10 years ago. The sensors use a technology called fluorescence quenching to measure DO levels.
Fluorescence is where a material takes in light from a specific color and, after a time, emits some of it at a different wavelength. Fluorescence quenching is the rate of the diminution of fluorescence due to another material, called the quencher. In this case, the quencher is oxygen. The degree of quenching depends on the oxygen level in the sample. Quenching is measured by the time lapse between the light being absorbed and emitted.

DO sensors use this method to calculate the exact amount of oxygen in the sample provided.

Mettler-Toledo’s InPro 6800 Offers the Latest Technology

Mettler-Toledo’s InPro 6800 dissolved oxygen sensor is the smart choice when you need a high level of accuracy combined with a rapid response. Available with your choice of a watertight VP connector or a T-82 connector in straight or angled versions for maximum flexibility, the InPro 6800 can easily be sterilized using steam.
The dissolved oxygen membrane on these sensors is more resistant to fouling than similar products in its class. The InPro 6800 and similar products from Mettler-Toledo make an excellent choice when dealing with dirty DO applications.
Jasper Engineering is an authorized manufacturer’s representative for Mettler-Toledo. We would be happy to provide you with additional information about the InPro 6050 dissolved oxygen sensor.
For more information, call (800) 776-6184 or e-mail us at sales@jaspereng.com.