What are the applications and laws of wear-resistant thermocouples?

1, Application of Wear resistant Thermocouples

Wear resistant thermocouples are ideal temperature sensors used in high-temperature and wear-resistant environments in industries such as metallurgy, chemical engineering, cement plants, power plants, and fluidized bed boilers. The WR series wear-resistant thermocouple adopts plasma spray painting technology, wear-resistant protective tubes made of different materials such as high chromium cast iron and high-temperature alloy, specially designed and manufactured for measurement occasions in high, medium and low temperature wear-resistant environments, and can be applied to circulating fluidized beds, boiling furnaces, and cement rotary kiln tail chambers.

2, The laws of operation and application of wear-resistant thermocouples

1. Law of homogeneous conductor

A closed circuit is formed by welding two ends of the same homogeneous material (conductor or semiconductor), regardless of the conductor. How the cross-section and temperature are distributed will not generate contact potential, the temperature difference potential will cancel out, and the total potential in the circuit will be zero.

It can be seen that wear-resistant thermocouples are composed of two different homogeneous conductors or semiconductors. If the material of the hot electrode is uneven, an additional heating potential will be generated due to the existence of a temperature gradient.

2. Law of intermediate conductor

In the wear-resistant thermocouple circuit, an intermediate conductor (third conductor) is connected. As long as the temperature at both ends of the intermediate conductor is the same, the introduction of the intermediate conductor has no effect on the total potential of the wear-resistant thermocouple circuit. This is the law of intermediate conductor.

Application: According to the law of intermediate conductor, in the practical temperature measurement application of wear-resistant thermocouples, the form of hot end welding and cold end open circuit is often used. The cold end is connected to the display instrument through a connecting wire to form a temperature measurement system.

Some people are concerned that using copper wire to connect the cold end of the wear-resistant thermocouple to the instrument to read the mV value may cause additional measurement errors due to the contact potential generated at the connection between the wire and the wear-resistant thermocouple. According to this law, there is no such error!

3. Law of intermediate temperature

The thermoelectric potential between the two contacts of the wear-resistant thermocouple circuit (at temperatures T and T0) is equal to the algebraic sum of the thermoelectric potential of the wear-resistant thermocouple at temperatures T and Tn and at temperatures Tn and TO. Tn refers to the intermediate temperature.

Application: Due to the non-linear relationship between wear-resistant thermocouples E-T, when the cold end temperature is not 0 degrees Celsius, the actual thermoelectric potential E (t, t0) of the known circuit cannot be directly used to lookup the table to obtain the temperature value of the hot end; It is also not possible to use the actual thermoelectric potential E (t, t0) of the known circuit to directly look up the temperature value from the table, and add the cold end temperature for accuracy. The measured temperature value at the fixed heating end needs to be corrected according to the law of intermediate temperature. Beginners often do not correct according to the law of intermediate temperature!

4. Reference electrode law