Medium-speed coal mill and medium-speed coal milling method suitable for high-moisture lignite

Abstract

The invention discloses a medium-speed coal mill and a medium-speed coal milling method suitable for high-moisture lignite. The medium-speed coal mill comprises a hot air door, a milling device, a coarse powder separator, a pre-drying device and a coal feeder, wherein the outlet of the hot air door is divided into two paths, one path is communicated with the air inlet of the pre-drying device, and the other path is communicated with the air inlet of the milling device; the outlet of the coal feeder is communicated with the lignite inlet of the pre-drying device; and the outlet of the pre-drying device and an opening positioned at the bottom of the coarse powder separator are both positioned just above the milling device. The medium-speed coal mill and medium-speed coal milling method which are disclosed by the invention can complete the milling of the high-moisture lignite.

Description

technical field [0001] The invention relates to a coal grinding equipment and method, in particular to a medium-speed coal mill suitable for high-moisture lignite and a method. Background technique [0002] Lignite is a resource with high moisture content, high ash content, low calorific value, and low ash melting point, accounting for 13% of the country's coal reserves. Lignite is cheap and has low industrial utilization value, so it is more suitable as thermal coal for thermal power plants. [0003] In the past, power plants mainly used fan coal mills to grind lignite, and the capacity of the units was relatively small. Due to the low output of fan coal pulverizers, it cannot be applied to large-capacity thermal power generation units. At present, medium-speed coal pulverizers are generally used for grinding lignite in large thermal power generation units. Common medium-speed pulverizers have the following problems in grinding lignite: [0004] 1) Due to the high moistu...

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Problems solved by technology

[0004] 1) Due to the high moisture content of lignite, the existing medium-speed pulverizers for grinding lignite generally have the problem that the outlet temperature of the pulverizer is too low, which limits the output of the pulverizer;

[0005] 2) Due to the high grindability and low density of lignite, the use of ordinary medium-speed coal mills to grind lignite is prone to problems that the air volume does not match the coal volume, and the coal fineness is not easy to control;

[0006] 3) Large air volume is required for grinding lignite. For this reason, the coal mill needs to choose a larger model, which will inevitably cause a large waste of coal mill grinding output, and the power consumption of the coal mill will also increase. If you choose a smaller model, There will be problems such as severe wear of the coal mill;

As a special coal type, lignite has its unique physical characteristics. It is necessary to fully understand and understand the characteristics of lignite, and conduct simulation tests on the test bench. Developed a special medium-speed coal mill suitable for high-moisture lignite, but none of the existing technologies can grind high-moisture lignite

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