Accurately detecting the acid dew point temperature in the flue gas is crucial during the operation of the heating furnace, and the acid dew point meter plays an irreplaceable role in it.

When a heating furnace burns sulfur-containing fuel, sulfur oxidation produces sulfur dioxide, which is further oxidized to sulfur trioxide. Sulfur trioxide combines with water vapor to form sulfuric acid vapor. When the temperature of the flue gas drops below the acid dew point temperature, sulfuric acid vapor will condense, causing serious low-temperature sulfuric acid dew point corrosion, scaling, blockage and other problems, affecting the operation safety and thermal efficiency of the heating furnace.

　　The working principle of the acid dew point meter is based on monitoring the relevant characteristics of sulfuric acid vapor.Taking the NP35A portable acid dew point meter as an example, its acid dew point probe is inserted directly into the boiler flue, and the detector on the probe includes a thermocouple and a platinum electrode. Thermocouples measure the surface temperature of detectors, while platinum electrodes measure the conductivity of acids deposited on the detector surface. By controlling the flow of cooling air to the detector element through an electric air pump, the rate of temperature drop on the surface of the element is strictly controlled to condense sulfuric acid vapor. The acid dew point temperature is determined based on the change in conductivity caused by condensation on the sensor surface (i.e. the change in current caused by the change in resistance). At the same time, the instrument can also measure parameters such as water dew point value, moisture content, dew point value, moisture content, and humidity value.

The acid dew point meter has many advantages. It can perform real-time online detection, such as the Nernst NP35A model, which allows operators to timely grasp the changes in the acid dew point temperature of flue gas, so as to quickly adjust the exhaust temperature of the heating furnace, control it within a range slightly higher than the acid dew point temperature, prevent corrosion, and improve operational thermal efficiency. Moreover, it has high measurement accuracy, with some instruments achieving an accuracy of ± 0.5 ℃ and a repeatability of ± 0.2%, providing users with reliable data. In addition, many models have automatic calibration function to ensure measurement accuracy, as well as multiple output control and alarm settings, which facilitate coordination with the control system and early warning of abnormal situations.

In summary, the acid dew point meter is a key equipment for monitoring the acid dew point temperature of flue gas during the operation and maintenance of heating furnaces, providing important support for ensuring the safe and efficient operation of heating furnaces.