What is the difference between the actual and theoretical heating principles of air heaters?
Air heaters use metal to generate eddy currents in an alternating magnetic field to generate heat, and are usually used in metal heat treatment. The principle is that when a thick metal is in an alternating magnetic field, a current is generated due to electromagnetic induction. When a thick metal generates a current, the current will form a spiral flow path inside the metal, so that the heat generated by the current flow is absorbed by the metal itself, which will cause the metal to heat up quickly. The electric air heater is mainly used to heat the required air flow from the initial temperature to the required air temperature, up to 850 ℃. It has been widely used in many scientific research and production laboratories such as aerospace, weapon industry, chemical industry and universities. Especially suitable for automatic temperature control and large flow high temperature combined system and accessory test. So what is the difference between actual and theoretical air heating principles?
Advantage
(1) Through continuous circulation of working medium, the flue gas is cooled, and the air heating effect is good, without using steam. The power consumption of the electric air heater circulation pump is only 10kW, which is extremely small compared to the heat power recovered from the flue gas.
(2) The air heater system operates at low pressure, the medium is hot water, and the temperature is low.
(3) Increase the wall temperature, reduce the corrosion of flue gas, and prevent ash blocking. No soot blower is required.
(4) Compared with the air heater heat pipe type, only a circulation pump is provided. Although it consumes a certain amount of electrical energy, it is convenient to operate, safe and reliable.
(5) The air heater is easy to set and arrange, without the need to modify the flue duct. Due to the thermal power requirements of the heat pipe of the electric air heater, the air duct where the heater is located is generally required to be higher than the flue duct. The forced circulation system of the electric air heater can choose the layout position according to the site conditions. The difference in pipeline resistance caused by the combination of different positions is solved by selecting a reasonable air electric heater circulation pump head.
(6) The power of air electric heater circulation pump is 10kW, which is equivalent to 4kg / h of standard coal, and its heat is equivalent to the enthalpy of steam of 30kg.
The power of the air heater is determined according to the calculation of the air volume and temperature rise. Under the premise that the air volume and temperature rise have met the needs, it is not appropriate to use too large air volume and excessive temperature rise. The power of the heater is too large, increasing energy consumption. Excessive air volume and temperature rise are not necessary. Comprehensive consideration, reasonable design, and determination of appropriate parameters are required. When using an air heater, only the outlet pipe of the electric heater is insulated, and no heat treatment is performed on the surface of the heater itself. The comparison data shows that adding a heat insulation layer on the surface of the air heater can reduce energy consumption by 5% to 10%. For long-term operation, the energy consumption saved is very considerable. Install insulation.
