The difference between box furnace direct heating and indirect heating
The difference between box furnace direct heating and indirect heating.
Joule heat generated by the current conductor as a heat source box furnace . Box furnaces are divided into two types, direct heating box furnaces and indirect heating box furnaces, according to the electric heat generation method.In the direct heating resistance furnace, the current passes directly through the material. Because the electric heating power of the industrial resistance furnace is concentrated on the material itself, the material heats up quickly and is suitable for processes that require rapid heating, such as the heating of forging blanks. This kind of resistance furnace can heat the material to a very high temperature. For example, the carbon material graphitization electric furnace can heat the material to more than 2500°C. The direct heating resistance furnace can be made into a vacuum resistance heating furnace or a protective gas resistance heating furnace. In powder metallurgy, it is often used for sintering tungsten, tantalum, niobium and other products.
When using this kind of furnace for heating, you should pay attention to:
①In order to make the material heated evenly, the conductive cross section and conductivity of each part of the material are required to be the same;
②The resistance of the material itself is quite small, and the working current is quite large to achieve the required electric heating power The power transmission electrode should be in good contact with the material to avoid arcing to burn the material, and the resistance of the power transmission bus should be small to reduce circuit loss;
③When supplying AC power, a short network should be reasonably configured to avoid excessive inductance and power factor Too low. The low thermal benefit of resistance furnace is his shortcoming.
