Due to the difference in the quality of the coal and the boiler used, there is a certain difference in the particle size requirements of the coal. Usually, the screening rate of the 200 mesh screen is 90%, and the grinding equipment can be adjusted to fineness; the coal is usually It is not very boring material. Usually, coal will be rich in more than 15% water, lignite and even up to 45%, so it is necessary for coal grinding equipment to get used to high moisture materials, and Canon can dry the materials together in the grinding. It is not necessary to set the dryer to add the drying process alone; the coal is rich in flammable evaporated water, and the coal itself is combustible, so it is necessary to have a flame retardant and explosion-proof method when grinding; the coal is rich in hard It is difficult to grind impurities. In the process of grinding, it is required to get used to hard impurities that are difficult to grind; it is necessary to grind dry powder to get used to the demand of pneumatic transportation. At present, the power mill grinding coal mostly uses traditional ball mills and other equipment. We all know more about these equipments, so I won't go into details here. Vertical large-scale thermal power plant vertical roller mill is mainly suitable for processing various non-flammable and explosive mineral products with Mohs hardness below 9 and 3, humidity below 6%, in metallurgy, building materials, chemical industry, mining and expressway construction. , water conservancy and hydropower and other industries have a wide range of applications, processing quartz, feldspar, calcite, limestone, talc, ceramics, marble, granite, dolomite, bauxite, iron ore, barite, bentonite, coal gangue, Ideal for coal and other materials, the finished product fineness can be adjusted from 0,613 mm to 0,033 mm. Working principle of vertical grinding in large thermal power plants:
In the main machine of the vertical roller mill of the power plant, the grinding roller assembly is suspended on the grinding roller hanger through the cross-arm shaft, the grinding roller hanger is fixedly connected with the main shaft and the blade holder, and the pressure spring is pressed on the outer end surface of the cantilever of the grinding roller bearing chamber. With the cross-arm shaft as the fulcrum, the grinding roller is pressed tightly on the inner surface of the grinding ring. When the main motor drives the main shaft to rotate through the transmission device, the blade mounted on the blade holder rotates synchronously with the grinding roller. The inner circle of the grinding ring rotates around its own axis while rolling. The motor drives the analyzer to rotate through the transmission. The higher the impeller speed, the finer the sorted powder. In order to ensure that the mill works under negative pressure, the increased air flow is discharged into the bag filter through the residual air pipe between the fan and the main engine, and is purified and discharged into the atmosphere. The air-selected airflow of the high-pressure suspension roller coal mill is circulated and flowed in the fan--milling--cyclone-fan, so it has less dust than the high-speed centrifugal pulverizer, and the operation workshop is clean and the environment is free from pollution. Large-scale thermal power plant vertical grinding performance characteristics:
1. Unique design. In the grinding chamber of the main machine, a pressurizing device of 1500kg-2000kg is designed on the upper part of the plum blossom frame. Under the same power, the output is increased by 10-30%, the grinding pressure of the grinding device is increased by 800-1500kgf, and the fineness of the finished product is fine. 1000 mesh.
2. The material has strong applicability and can be used for various materials with Mohs hardness below 9 and 3.
3. The dust removal effect fully meets the national standards.
4. The grinding roller device adopts high quality and efficient processing technology, and the overlapping multi-stage sealing ensures a good sealing effect.
5, the grinding roller, grinding ring replacement cycle is long, eliminating the shortcomings of the centrifugal crusher wearing parts replacement cycle is short.
6. The grinding device adopts overlapping multi-stage sealing and has good sealing performance.
Many power plants have selected or switched to the more advanced vertical roller mill (also known as vertical roller mill) system for coal powder preparation for energy conservation and environmental protection needs. The vertical grinding coal system is usually composed of a vertical grinding machine, fine powder collecting equipment, fans, pipes and the like. The operation process is that the raw coal enters the vertical roller mill and is then brought into the classifier by air (or hot air). The fine coal powder is collected by the fine powder collecting equipment and then put into the coal powder storage or pulverized coal conveying equipment.