Optimization And Transformation of Fast Opening High-pressure Membrane Filter Press System in Coal Washing Plant

De watering machine,Filter press is a commonly used tail coal processing and dewatering machine in coal washing plants at present, which has the advantages of strong processing capacity, good dewatering effect, low noise, and low energy consumption. The fine coal slurry (particle size below 0.25mm) of Huipo Bottom Coal Washing Plant is dehydrated using XAGZ450/2000-U quick opening membrane filter press, and the products produced are transported outside by belt conveyor. The quick opening diaphragm filter press machine has a certain degree of blockage during use, which affects the filtration effect of fine coal slurry. Therefore, targeted optimization of the quick opening diaphragm filter press system is carried out in the article to improve the treatment effect of fine coal slurry to a certain extent. Overview of Coal Washing Plant and Usage of Filter Press: The Huipo Bottom Coal Washing Plant is a pithead type coal washing plant built to support the Huipo Bottom Mine, with a design capacity of 1.5 million tons per year. The raw coal for washing comes from the Huipo Bottom Mine. Adopting a combined process of desliming and non pressure feeding, three product heavy medium, TPS separator, and flotation. The dehydration of flotation clean coal in the factory is completed by two XAGZ450/2000-U quick opening diaphragm filter presses. Due to the multiple working steps, complex programs, and multiple control points of the quick opening diaphragm filter press, the equipment has been operating with high failure efficiency and low dewatering capacity for flotation clean coal, resulting in high water content efficiency of clean coal. Therefore, it is necessary to upgrade and optimize the existing equipment. The structure of the XAGZ450/2000-U quick opening membrane filter press used in the Huipo Bottom Coal Washing Plant consists of a main engine, auxiliary engines, valves, pipelines, etc Install a filter machine in a sealed pressurized chamber, and transport the fallen material generated after pressure filtration using a scraper conveyor. Install a discharge device at the machine head position. The turbid liquid formed during the pressure filtration process is pumped into the filter tank through the feed pump. Under the pressure of the pressurized chamber, the liquid produced by filtration flows out, and the solid particles form a filter cake that rotates with the filter disc. Then, they are transported to the discharge device through a scraper conveyor at the distribution valve position. When a certain amount of material accumulates in the discharge device, it will be intermittently discharged outside the filter machine, and the entire pressure filtration process can be fully automated.

The working principle of the dewatering filter press is that when filtration begins, the coal slurry is pushed by the feed pump and enters each filter chamber through the feed inlet in the middle of the two side thrust filter press plates. The coal slurry is separated into solid and liquid by the pressure of the feed filter press pump. Due to the action of the filtering medium, solids larger than the gaps in the filter cloth remain in the filter chamber to form a filter cake; The filtrate and a small amount of extremely fine coal slurry smaller than the gap of the filter cloth are discharged through the drain valve and recycled. In use, if it is necessary to filter and form a filter cake with low moisture content, high-pressure compressed air can be introduced into the air inlet in the upper right corner of the push up plate to press the filter press cake and further reduce its moisture content; High pressure air can also be introduced from the feeding port in the center of the compression plate end, passing through the filter cake layer and allowing the intermediate air to flow through, further squeezing out excess moisture from the filter cake.

Analysis of Problems in On site Application: During the on-site application of the quick opening diaphragm filter press, it was found that in case of emergency shutdown of the equipment or failure of the belt conveyor transporting clean coal, it is necessary to promptly discharge the materials from the quick opening diaphragm filter press. However, due to the high liquid level in the feeding cylinder of the quick opening diaphragm filter press, the filter machine has difficulty discharging materials, which can easily cause the main shaft of the filter machine to become blocked. If material discharge is forced, there may be a situation of overflow from the feeding drum. When the quick opening diaphragm filter press cannot be used normally, the coal slurry in the concentration tank will not be discharged in a timely manner, affecting the normal production of the coal washing plant.

Research on System Optimization: During normal use of the filter machine, it was found that the liquid level in the feeding cylinder is often above 50%. If the material cannot be discharged normally, it is very easy for the program to cause blockage. Therefore, the article considers optimizing the filter system from aspects such as the feeding process and spindle speed.

4.1 Optimization of Spindle Speed: In general, the reasonable range for setting the spindle speed of the filter is 0.87-1.5r/min. When dewatering fine coal slurry on site, the filter speed is set to 1.01r/min. From previous research results, it has been found that the speed of the filter machine has an impact on the moisture content of the product, the number of coal slurry plates, and the moisture content of the product. The lower the spindle speed, the fewer coal slurry plates there are, and the lower the moisture content of the product, making it more prone to stalling; The higher the rotational speed, the higher the moisture content of the product. If the rotational speed exceeds a certain value, the moisture content of the product will not meet the requirements. Based on the above analysis and previous research results, it has been decided to increase the spindle speed of the filter from 1.01r/min to 1.30r/min to ensure efficient operation of the filter.

4.2 Optimization of Material Discharge Process: When the liquid level in the feeding cylinder is below 20%, the bottom flow pump will automatically load the material. When the liquid level is above 80%, the bottom flow pump will stop working. If there is an urgent need to stop coal slurry or coal during the pressure filtration process, the bottom flow pump will still automatically operate based on the liquid level height of the feeding cylinder. Generally, the liquid level height in the feeding cylinder is between 60-80%. At this time, the slurry tank material flows into the feeding cylinder. When the inflow exceeds 40% of the liquid level, the feeding cylinder will overflow. If the material in the slurry tank cannot be quickly emptied, the filter machine is extremely prone to rotational blockage during subsequent operation. If the material in the slurry tank can be emptied, there will be no rotational blockage. The problem of material emptying in the slurry tank can be solved by modifying the feeding method of the quick opening diaphragm filter press slurry tank. At present, there are two main methods for discharging the slurry tank of the quick opening membrane filter press: reducing the liquid level height in the feeding cylinder to ensure sufficient space for storing materials. However, when the liquid level in the slurry feeding cylinder drops too much, there is a problem of frequent starting of the bottom flow pump, which is not conducive to the efficient development of coal washing work; If the decrease in liquid level height is too small, it will not effectively increase storage space, and the material in the feeding cylinder will still overflow. Targeted improvements can be made to the discharge system to temporarily store the slurry tank materials in other locations. The specific improvement method is to optimize the layout of the discharge pipeline, so that the materials in the slurry tank can be discharged into the protection box and then flow back to the concentration tank; Use a bottom flow pump to pump the material from the concentration tank to the upper feeding cylinder, thereby achieving cyclic feeding. After the above improvements, the discharge of materials in the slurry tank will not affect the liquid level height in the feeding drum, effectively solving the problem of overflow in the feeding drum.

Analysis of the transformation effect: Optimization of the spindle speed and discharge process of the fast opening diaphragm filter press in the Huipo Bottom Coal Washing Plant. After optimization, the moisture content of the products produced by the filter press is within a reasonable range. At the same time, the material discharge path in the slurry tank is transferred from the original feeding drum to the concentration tank, effectively avoiding overflow problems in the feeding drum. During on-site renovation and optimization, flange connections are used for material discharge pipelines. Even if the pipelines are severely worn or blocked, they can be disassembled and replaced in a timely manner. After on-site application, investigate the working condition of the modified quick opening diaphragm filter press. On site inspection found that when there is an emergency shutdown of coal slurry or coal in the coal washing plant, the materials in the slurry tank can be discharged into the protection box to achieve timely emptying of the materials. The problem of filter spindle blockage has increased from an average of once every 3 months before the renovation to once every 9 months. Through optimization, the occurrence rate of filter spindle blockage has been effectively reduced. By optimizing, the annual investment can be reduced by about 103000 yuan, which not only reduces the labor intensity of operators but also shortens the equipment maintenance time, and can to some extent improve the economic benefits of the coal washing plant. At the same time, through upgrading and transformation, the moisture content of the product has been reduced, the usage of tap water has been lowered, and a significant amount of social costs have been saved. Reduced the labor intensity of the operators, from the original four person position, now only two people are needed. Greatly reducing the pollution of coal slurry to the surrounding environment and the noise pollution of flotation workshops, bringing significant social benefits.

Conclusion: This article optimizes the XAGZ450/2000-U quick opening diaphragm filter press system used for fine coal slurry in the Huipo Bottom Coal Washing Plant. Specifically, the spindle speed is optimized from 1.01r/min to 1.30r/min. The produced products not only meet the requirements for moisture content but also improve the operational efficiency of the filter press; Optimize the discharge process of the slurry tank, specifically by discharging the materials in the slurry tank into a protective box and then flowing back to the concentration tank, in order to avoid the problem of material overflow caused by the flow of materials into the feeding cylinder in the slurry tank and reduce the occurrence rate of main shaft blockage in the filter. After on-site application, the occurrence rate of filter clogging increased from 3 months to 9 months, and it is expected to save about 300000RMB in annual costs, effectively reducing the number of filter spindle clogging and improving the comprehensive start-up rate of coal washing equipment. After the formal application of the fast opening diaphragm filter press in the Huipo Bottom Coal Washing Plant, it has saved a lot of operating costs for the plant due to its advantages of fast filtration and discharge speed, low moisture content in the filter cake, large processing capacity, and high degree of automation. At the same time, the machine has strong adaptability to the particle size composition of the feed and has broad development prospects in processing materials with high viscosity, fine particle size, and high concentration.