|
|
|
|
|
|
|
|
Materials of components in rotary drum dryers
|
|
The material selection of the components of the drum should be determined according to factors such as nature of feedstocks, stress, wear and tear of components, and processing conditions.
The materials of the cylinder should be selected in terms of strength, wear resistance, corrosion resistance, and thermal conductivity, etc. The cast cylinder generally adopts HT200; when the pressure is high, high-strength metamorphic gray cast iron (HT250, HT300, QT400, etc.) or cast steel can be used. The strength of cast steel is higher, but the castability and wear resistance are not as good as cast iron.
When selecting gray cast iron as the drum material, the coordination between working pressure and drum diameter should be considered. When the diameter of the cylinder is less than or equal to 1000mm, the working pressure in the cylinder shall be kept less than or equal to 0.6MPa; when the diameter of the cylinder is greater than 1000 ~ 2000mm, the working pressure shall be less than or equal to 0.3MPa.
In addition to the above, the cast steel cylinder shall display good thermal conductivity and corrosion resistance, so that it can suit for low pressure and low temperature in hot water heating conditions and where it requires the final product to be without iron.
A wide range of materials are used for welded cylinders. For non-corrosive materials, Q235a, 16MnR, 20R and other materials can be used. For corrosive materials that require clean products, 2Cr13 and other materials can be used. The cylinder used for textile drying can be built with copper plate of fast heat transfer.
The material of the end cap and the end shaft are mainly selected by the strength and wear resistance. For integral casting structure,HT200, QT400 cast iron and ZG200-400, ZG230-450 cast steel are commonly used. The material of welded structure can be consistent with the cylinder. The end shaft part is usually processed out of high-quality steel rods or forgings such as 25, 35, and 45.
|
|
|
|
|
|
|
|
|
|
