Problems and improvement measures of active iron powder drying system Henan Hongxing


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Problems and improvement measures of active iron powder drying system

For the comprehensive utilization of sludge, the Red Star factory has carried out the technological research on the separation of activated iron powder for chemical industry by using coarse-grained sludge. utilize Ball mill Magnetic separator table dryer The iron powder in the sludge can be purified to more than 88% grade by grinding, beneficiation and drying. It can be used as reducing agent for titanium dioxide production and high value-added application of iron and steel sludge resources. However, in the process of iron powder drying, the drying pipeline is frequently blocked due to the large water content; the failure rate of the crusher is high, which has a great impact on the production. In order to solve this problem, the pre dryer system was reformed, The drying efficiency is improved The continuous and stable operation of drying system is ensured.

 Active iron powder drying system

1、 Problems in drying system

1. Bend wear

The elbow of the main pipe of the dryer will be worn out if it is used less than two times in total. The application of steel plate patch can prolong the service life for 2 days, which will affect the normal production of the system. After replacing the wear-resistant elbow, the situation is improved, but the wear problem can not be seen from the equipment. The main reason of wear is that the active iron of 0.600-0.125 mm fine iron particles suddenly changes direction in the process of high-speed movement with air flow, which causes the adjustment impact of iron particles on the outward direction. In addition to the serious wear of the elbow, the discharge pipe of the dried iron powder also showed great wear.

2. Powder hanging in pipeline

Because the inlet temperature of iron powder is only about 180 ℃ in the drying process, the iron powder can not be dried in time in the process of high-speed flow of materials and hot air, so that part of the iron powder is attached to the inner wall of the pipeline. After a long time, the iron powder on the inner wall of the pipeline thickens and blocks the pipeline, and the hot air and iron powder pass through are limited, which reduces the drying efficiency and affects the normal operation of the system. Especially when the active iron separation process is changed and the screw classifier replaces the shaker, the wall hanging is more serious due to the increase of iron powder, which can last for 3 in the early stage and can only support 1 at present.

3. The wall material damages the crusher

The wall hanging of iron powder not only affects the drying efficiency, but also limits the heat and iron powder throughput. The thick wall hanging materials fall off after being impacted by air flow or heat expansion and cold contraction, and the falling wall hanging materials are relatively hard. They fall into the high-speed rotating disintegrator from the upper part of the pipeline, which damages the rotating cage. The cage, which was remapped, has been damaged many times. According to preliminary statistics, more than 85% of the equipment downtime is due to the broken wall material.

4. Low drying efficiency

The set temperature of drying system is 160 ℃ and low temperature zone is 70 ℃. In use, because the moisture content of iron powder is more than 30%, it becomes fluid. When the amount of iron powder entering the drying system increases, the temperature of drying airflow will drop, and the production line will be forced to reduce efficiency or even shut down.

2、 Improvement measures

The dissociation and separation process of active iron powder is fully analyzed. On the basis of continuous test and improvement, the mechanical pre dewatering and the structure transformation of the crusher are adopted, and the drying system is adjusted to meet the needs of the drying system.

1. Drying pre dehydration

The moisture content of the active iron produced by the active iron production line is 30% - 40%, which is mixed with the raw materials to form a fluid state. After entering the drying system, the humidity in the pipeline will increase, the drying burden will be heavier, and the drying efficiency will be affected. Therefore, the amount of iron powder entering the drying system should be pre dehydrated. When the active iron production line works, the output is 1.5t/h. In order to ensure the continuity of dehydration and drying in the production line, continuous dehydration is adopted for pre dehydration.

The pre dewatering structure consists of a rack and a dehydration device installed on the rack. The dehydration device is a mesh belt structure. The mesh belt is 0.074mm screen, which can not only carry and transport materials, but also separate materials from water. The mesh belt has two opposite layers, the upper layer is the load layer, the transport device uses spring support, and the vibration motor is installed on the support of the transport device. When working, the transport device vibrates under the action of vibration motor. The material to be dehydrated falls onto the mesh belt through the feed inlet and moves forward with the mesh belt. During the operation, the material and water are separated, and the mesh belt vibration will accelerate the dehydration. When the material carried by the mesh belt reaches the drum, the material will fall off under the action of self weight. The vibration of the transport device is conducive to the separation of the material and the mesh belt, and the purified water falls to the bottom water collecting tank and can be reused.

2. Improvement of disintegrator

Through the analysis of the structure and working process of the crusher, it is found that the span of the main breaking arm is large, and the iron bracket falls on the high-speed running scattering arm, which causes deformation or interruption of the breaking arm and causes equipment failure. Therefore, a supporting disc is added in the middle of the arm to support it from the back to increase the strength of the arm.

3. Installation pneumatic vibration

In order to reduce the sticking on the pipe wall, pneumatic vibration is installed on the pipeline, and the pipe is knocked regularly to remove the newly formed wall sticking material, so as to avoid the iron bracket caused by bonding, so as to damage the squirrel cage and break the arm.

4. Use of dryer

Temperature control: in order to increase the output, the inlet temperature should be increased as much as possible. If the outlet temperature is too high, it will cause waste, and at the same time, the quality of the materials to be dried will decline, and the color of the materials will turn black seriously. In order to ensure the normal operation of the production line, the temperature in the high temperature zone of the dryer system is controlled at 180 ℃ and the temperature in the low temperature zone is controlled above 80 ℃.

Feeding quantity control: before the material enters the drying system, it must be lumpy to facilitate the normal feeding and the normal operation of the dryer. In order to ensure drying, the uniformity of materials entering the drying system should be controlled.

After the implementation of the above improvement measures, the improvement is obvious. The mesh belt type mechanical pre dewatering is adopted to reduce the water volume to 10% ~ 15%; the disc is added in the middle of the breaking arm to increase its strength, reduce the frequency of damage and effectively reduce the failure rate of the equipment. Through the process improvement, the drying output is increased from 1.5t/h to 2.5t/h, the product is stable and the production line runs continuously and stably.

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