Pulverizing system and process for reducing ash and improving quality of circulating materials in medium-speed coal mill in coal-fired power plant

Abstract

The invention discloses a pulverizing system and process for reducing ash and improving quality of circulating materials in a medium-speed coal mill in a coal-fired power plant. Starting from the angle of characteristic particle sizes of the circulating materials and qualified pulverized coal in the pulverizing system, the grading particle size of a built-in pulverized coal classifier of the coalmill is optimized, and secondary grading operation of an external cyclone classifier is matched, so that the discharge of the circulating materials in the coal mill is realized; mineral components continuously accumulated in the circulating materials are removed through a pulsating airflow separation bed, so that the internal circulation ratio of the coal mill is reduced while the quality of the qualified pulverized coal is ensured to be improved. By means of the process, the multiple purposes of improving the quality of the qualified pulverized coal, improving the combustion efficiency of a boiler, reducing pollutant emission and the like can be achieved, the internal circulation ratio of a mill can be effectively reduced, equipment abrasion and energy consumption are reduced, and finally, all-in-one integration of grinding, grading and sorting of a coal grinding and pulverizing system of the power plant is achieved.

Description

technical field [0001] The invention relates to a pulverizing system and process for reducing ash and improving the quality of circulating materials in a medium-speed coal pulverizer of a coal-fired power plant, so as to realize reducing ash and improving the quality of coal during the grinding process and before combustion. [0002] technical background [0003] Most of the coal used in power plants is low-quality raw coal with high ash content, which has high gangue content, large ash discharge, low calorific value and poor grindability. Raw coal needs to be ground many times to meet the particle size requirements of qualified coal powder, resulting in the quality of the circulating material inside the mill being much greater than the output of the coal mill. According to research, the circulation rate in the mill (the ratio of the mass flow rate of the circulating material to the output of the mill) is as high as 8 to 10 times. A large amount of coal-based minerals with h...

AI Technical Summary

Problems solved by technology

However, since the interior of the coal mill is a high-temperature and high-pressure closed operating system, if the interception sampling of circulating materials is to be realized in the mill, it is necessary to complete the dynamic balance of pressure and temperature inside and outside the sampling node, and to simultaneously adjust the working parameters of other parts of the mill , leading to greater difficulty in the diversion operation of circulating materials under actual working conditions

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