ABSTRACT
Temperature measurement is required in the control of several types of equipment, such as a cement kiln, spray dryer, or powder calcinator. The temperature sensors are classified in two groups: thermal contact and radiation thermometers. The temperature of powder stored in a vessel will be measured by use of a thermal contact thermometer. It also includes thermocouples, electric-resistance thermometers, thermistors, and transistor thermometers. Thermocouples are composed of two different types of metal wires connected at both ends, making a loop. One of the ends is called the hot junction (sensing point) and the other the reference junction (or cold junction). Electric-resistance thermometers utilize the characteristic of metals that the electric resistance of conductors increases with an increase in ambient temperature. All objects emit thermal radiation energy depending on their temperature. Therefore, the temperature of particles can be estimated by detecting the thermal radiation energy. Radiation thermometers need no thermal contact with particles.
