The cryogenic air separation equipment achieves the separation of air components at low temperatures, and has high requirements for the water content of the gas entering the distillation tower for separation. Therefore, the configuration of high-performance trace water analyzers is crucial for the continuous, safe, and stable operation of the air separation equipment. At present, trace water analyzers widely used in the air separation industry can be divided into three types according to different measurement principles: electrolytic, capacitive, and cold mirror. Today, we will introduce the application and maintenance of one type of cold mirror micro water analyzer in air separation equipment.

The measurement principle of the cold mirror micro water analyzer (dew point meter) is that when the measured gas enters the measuring room of the instrument, it passes over the cold mirror surface. When the temperature of the mirror surface is higher than the dew point temperature of the moisture, the mirror surface is in a dry state. At this time, the light emitted by the light source in the photoelectric dew detection device is almost reflected on the mirror surface. The photoelectric sensor senses and outputs a photoelectric signal, which is compared, amplified, and driven by the control circuit to cool the mirror surface. When the mirror surface temperature drops to the moisture dew point temperature, dew (frost) begins to form on the mirror surface, the light shines on the mirror surface and diffuse reflection occurs, and the reflection signal sensed by the photoelectric sensor weakens accordingly. This change is compared and amplified by the control circuit, and then the thermoelectric pump excitation is adjusted to reduce its cooling power appropriately. Maintain the mirror temperature at the dew point temperature of the sample gas. The mirror temperature is sensed by a platinum resistance temperature sensor closely attached to the cold mirror surface, and the resistance value of the platinum resistance is measured and converted into the dew point value.

The method of measuring gas water content using a cold mirror micro water analyzer is the most accurate and reliable, and is widely used for measuring trace water in air separation equipment. At present, the price of cold mirror micro water analyzer (dew point analyzer) is relatively high and requires experienced personnel to operate and maintain it.