Under limited conditions, pulverized coal is heated in isolation from air to obtain water, carbon hydroxide and hydrocarbons. The volatile content of pulverized coal is one of the main indicators to measure the quality of pulverized coal. Pulverized coal with good quality has a high volatile content.
Adding pulverized coal to green molding sand for cast iron can prevent sand adhering defects on the surface of castings, improve the surface finish of castings, reduce sand inclusion defects, and improve the collapsibility of molding sand.
For green ductile iron castings, it can effectively prevent subcutaneous blowholes. Circular vortex burners can be used, and the air does not need to be preheated. Nowadays, LM vertical pulverizers are mostly used for pulverized coal processing machines, The problems of pulverized coal fineness and output are effectively solved. The characteristics of the pulverizer are briefly introduced below.
1. Due to the difference of coal quality and boiler's requirements on coal particle size, it is generally 200 meshes, and the passing rate is about 90%. The grinding equipment should be able to adjust the fineness.
2. Generally, the coal contains more than 15% moisture lignite, even up to 45%. Therefore, the grinding equipment must be suitable for high moisture, and it is better to dry the materials at the same time of grinding without having to set up a separate dryer to increase the drying process.
3. The coal contains flammable volatile water and the coal itself is combustible, so flame retardant and explosion-proof measures must be taken during grinding.
4. Coal contains hard impurities that are difficult to grind, It is required to adapt to hard impurities that are difficult to grind during grinding.
5. The dry powder must meet the needs of pneumatic conveying.
At present, the power plant uses ball mill, Raymond mill and other equipment for coal grinding. Due to the mechanical collision between the steel ball and the cylinder liner, and between the steel balls, the rotation of the cylinder does not directly affect the material grinding, so the ball mill has the defects of low grinding efficiency, large wear, and large noise, which is not suitable for the fly ash with strong corrosion.
Raymond mill generally has a small processing capacity. Its working principle is to use the centrifugal force generated by the rotating spindle to make the grinding roller swing to the inner wall of the grinding ring, so that the material is crushed between the grinding roller and the inner wall of the grinding ring, and then the fine powder is blown to the collector for collection by the air blower. Its main disadvantages are high power consumption, low output, large media wear and serious dust pollution.
SMMVIK Machinery has introduced the LM vertical mill in view of the shortcomings of existing pulverized coal grinding equipment, which has great advantages in the process of pulverized coal grinding. You are welcome to consult, and we look forward to your arrival.
