Infrared thermometers are widely used in refractory material factories due to their high temperature measurement accuracy. In key tunnel kilns, there are many temperature measurement points inside. Infrared thermometer has the characteristics of multiple temperature measurement points and long continuous working time. If the temperature parameters are not well controlled, it will bring significant economic losses to the production enterprise. Therefore, selecting appropriate temperature measurement methods is an important link to ensure the normal operation of the kiln. There are two traditional temperature measurement methods for tunnel kilns: one is to use thermocouples for temperature measurement. The characteristic of this method is high temperature measurement accuracy, which can be connected to a recorder or control system for closed-loop control. Its disadvantage is short service life, especially in high-temperature kilns above 1300 degree where the electric coupling consumption is extremely high, the price is also very expensive, and the equipment operation cost is high; The first method is an optical pyrometer, which measures temperature based on the color of the object being measured. As it does not directly contact the high-temperature area, it has a long service life, but the measurement accuracy is low, there is no electrical signal output, it cannot be automatically recorded, and there are also human factors that affect its authenticity. The application of HD series infrared thermometer can effectively overcome the above shortcomings. This instrument has high measurement accuracy (up to ± 0.5 percent ), and can output electrical signals like thermocouples for automatic recording and control. It also has advantages such as long service life (more than five years), simple operation, and small human error. Therefore, the HD series infrared thermometer is an ideal temperature measuring instrument for high-temperature tunnel kilns. In the application of HD series infrared temperature detectors in tunnel kilns, according to different user requirements, there are two commonly used methods: single point temperature measurement and multi-point switching temperature measurement. The introduction is as follows:
The temperature measurement unit collects temperature. Connect the 4-20MA analog signals output from each unit's instrument box to a multi-point recorder or control actuator, and communicate with computers, printers, and other devices through RS-232 ports for data. The temperature measurement unit in this system is usually selected with high accuracy.
Switching temperature measurement system: This system processes signals by connecting the infrared probe signals installed at each temperature measurement point to an HDMU-2 multi-point thermometer. And respectively output 1-5V temperature signals corresponding to each temperature measurement point for recording by multi-point recorders. At the same time, temperature data can also be directly input to a computer through the RS232 port for analysis and processing by the computer. It can also be directly printed out by connecting to a printer.
Among the above two solutions, the single point temperature measurement system has an independent temperature measurement and signal processing system for each temperature measurement point, and its output analog and digital signals are real-time continuous signals with fast response speed. It can serve as a real-time control signal for the control execution mechanism to achieve closed-loop control. The multi-point switching temperature measurement system, although its output analog signal is also continuous, has a certain lag with the real-time temperature value, so it can only be used for data acquisition and recording, and should not be used as a control signal. Its advantage is good cost-effectiveness, which can reduce equipment costs in situations where the usage requirements are not too high.
In other refractory kilns, such as inverted flame kilns and edge kilns, due to the limited number of temperature measurement points, single point temperature measurement schemes are more commonly used. There are also devices that use the HDIR-3 handheld infrared thermometer, but this instrument can only measure the temperature of the kiln intermittently, and each measurement record requires manual operation, which cannot achieve automatic continuous measurement.
