The electric heating rotary kiln, also known as electric rotary kiln, is rotary kiln equipment that uses resistance material as an electric heating element for heating. Electric heating is generally used in indirect heating rotary kilns. The electric rotary kiln is important equipment for roasting metal oxides or chemical products in the non-ferrous metallurgy and chemical industries.
Heating Device of Electric Heating Rotary Kiln
Electric heating rotary kiln heated by alloy furnace wire heater
The heating elements of the electric rotary kiln use nickel-chromium alloy (1Cr18Ni9Ti or Cr25Ni20Si2) or iron-chromium aluminum alloy (0Cr13A14 or 0Cr25A15) to make spiral heating elements, which are generally installed on both sides and bottom of the electric heating rotary kiln. There are four groups of heating elements in the electric heating rotary kiln, that is, four heating temperature control zones, and the temperature of each zone can be set separately. Its rated heating power can reach 300 kW, which can meet the heating requirements of electric heating rotary kiln, and the power will be reduced after the stable operation of the equipment. The advantages of the electric rotary kiln heating device are that the heating is uniform and the thermal efficiency is high.
Electric heating rotary kiln with silicon carbide rod
Another type of electric heating rotary kiln heating furnace uses silicon carbide (SiC) as the heating element. There are two rows of silicon carbide rods, 24 in each row. A total of 48 silicon carbide rods are electrified to generate heat to heat the kiln pipe, and the heat is transferred to the material through the pipe wall. The temperature of the electric heating rotary kiln is controlled in three stages, and the temperature inside the furnace body structure is measured and controlled by three thermocouples. By increasing or decreasing the number of 48 silicon carbide rods energized, the temperature required for the oxidation and roasting of the material can be adjusted and controlled to realize automatic temperature control.
As the heating element, the silicon carbide rod is only arranged at the bottom of the electric heating rotary kiln. Although this arrangement is single-sided radiation heat transfer, because the kiln pipe rotates at a uniform speed, the heating of the electric rotary kiln is still very uniform. As the heating element of the electric heating rotary kiln, silicon carbide rods are easy to repair and replace without affecting the thermal efficiency of the rotary kiln and normal working conditions.
Working Process of Electric Heating Rotary Kiln
The complete system of electric heating rotary kiln consists of feeding device, kiln body, discharging device, electric heating device, control unit, etc. The electric heating device heats the surrounding environment of the materials in the kiln to gradually increase the temperature. When the temperature measured by the thermocouple reaches the requirement, the temperature will not continue to rise, and the material can be discharged after the reaction time reaches the specified value, and the whole process is safe and efficient.
- The feeding system is usually equipped with a screw feeder for quantitative conveying. According to the characteristics of the material, it can be divided into a single screw, double screw, and shaftless screw.
- The heating kiln generally includes a pre-heating zone and a high-temperature heating zone. There are multiple temperature zones in the pre-heating zone and the high-temperature heating zone, where the temperature of each temperature zone can be set separately, and the temperature of each zone of the equipment is required by the process.
- The heating kiln body has a certain inclination angle, the feed end is high, and the discharge end is low. The material rotates with the furnace tube, passes through various heating temperature zones from the feed end, and is discharged from the discharge end.
- The heating resistance wire is arranged at the bottom of the kiln body to indirectly heat the material.
- The cooler is usually a drum cooler, the material passes through the inside of the cylinder, and the outside is sprayed with water to indirectly cool the material to meet the discharge temperature requirements.
Advantages of Electric Heating Rotary Kiln
Compared with gas-fired rotary kiln and oil-fired rotary kiln, electric power used by electric rotary kilns is the cleanest energy source. Electric energy can be easily connected to the factory and supplied to the electric heating rotary kiln along with the power supply line.
The advantages in the production process of the electric rotary kiln are also obvious.
- High thermal efficiency, no smoke, no ash, and slag to take away obvious heat.
- It is easy to automatically control the conditions, the kiln temperature control accuracy is high, and it is suitable for the narrow pre-firing temperature process.
- In addition, the electric rotary kiln does not need to build fuel storage and transportation station, which simplifies the work of fuel procurement, transportation, and safety management. During the production process, the corrosion of the kiln body due to SO2 gas and environmental pollution problems can be avoided. Therefore, the electric heating rotary kiln is more economical than the gas fuel rotary kiln and the oil fuel rotary kiln.
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