How to choose the flow direction of rotary dryer correctly? -Henan Red Star

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How to choose the flow direction of rotary dryer correctly?

Rotary Dryer It is a kind of drying equipment with large production capacity, wide application range, small liquid resistance, large allowable fluctuation range and convenient operation. In the dryer, the flow direction of wet material and heat carrier can be divided into two types: parallel flow and counter flow, and there are also reverse flow and parallel flow. So how to choose the right flow direction?

 dryer

Concurrent flow

The moving direction of the material is the same as that of the heat carrier. During the drying process, the material with high moisture content meets the heat carrier with low moisture content at the inlet, where the drying driving force is large. At the outlet, the material with lower moisture content contacts with the heat carrier with higher moisture content, and the drying driving force is small. Therefore, the characteristic of parallel flow is that the driving force gradually decreases along the direction of material movement. In the drying stage, the driving force of drying is reduced to very small, so the drying speed is very slow, which affects the production capacity.

The parallel flow mode is applicable to the drying of the following materials:

① When the humidity is high, the material is allowed to dry quickly without cracking or coking.

② After drying, the material can not withstand high temperature, that is, the product will decompose and oxidize when meeting high temperature.

③ The hygroscopicity of the dried materials is very small, otherwise the dried materials will absorb moisture from the heat carrier and reduce the product.

Against the Current

The moving direction of material is opposite to that of heat carrier. At the entrance, the material with high humidity contacts with the heat carrier with high humidity and low temperature, and at the outlet, the material with low humidity contacts with the heat carrier with high humidity and low humidity, so the drying driving force of each part in the dryer is not different, and the distribution is relatively uniform.

The countercurrent mode is suitable for drying the following materials:

① When the material is in high humidity, rapid drying is not allowed, so as to avoid cracking and other phenomena.

② The dried materials can be resistant to high humidity without decomposition and oxidation.

③ The material with higher moisture absorption and drying property.

④ It requires high drying speed and high drying degree.

The disadvantage of countercurrent flow direction is that the humidity of the material at the inlet is low, while the humidity of the heat carrier is very high. When contacting, the water vapor in the heat carrier will cool and condense on the material, which will increase the humidity of the material and prolong the drying time, which will affect the production capacity.

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