Coal pulverizing system and method suitable for high-moisture coal types

Abstract

The invention discloses a coal pulverizing system and method suitable for high-moisture coal types. The coal pulverizing system comprises a primary air fan, an air preheater, a hot primary air pipe, acold primary air pipe, a hot air adjusting door, a cold air adjusting door, a heating device, a coal mill, a controller, a hot primary air quantity measuring device, a coal mill outlet temperature measuring device and a primary air pulverized coal pipe. Cold air at an outlet of the primary air fan is divided into two paths: one path directly enters an inlet pipeline of the coal mill through the cold primary air pipe, and the other path enters the air preheater to be heated, the heated hot primary air is reheated by the heating device and then enters the inlet pipeline of the coal mill to be mixed with the cold primary air, and the mixed hot air enters the coal mill to dry pulverized coal, so that the purpose of improving the drying output of the coal mill is achieved. The system can effectively improve the temperature of the hot primary air, improve the drying output of the coal mill, enhance the adaptability of the coal mill to coal moisture, prevent pulverized coal condensation andpipe blockage caused by over-low outlet temperature of the coal mill, enable a unit to burn high-moisture coal, reduce the unit price of standard coal, reduce the operating cost, facilitate safe and stable operation of the unit and achieve good economic benefits.

Description

【Technical field】 [0001] The invention belongs to the technical field of pulverizing systems in thermal power plants, and relates to a pulverizing system and method suitable for high-moisture coal. 【Background technique】 [0002] my country is rich in coal resources, and thermal power generation still occupies a dominant position in the energy power generation market. With the rapid growth of my country's economy, the consumption of coal will increase, the supply of coal will become increasingly tense, and the price of coal will continue to rise . In recent years, due to excess coal-fired unit assembly capacity, continuous rise in coal prices, and continuous reduction in power generation utilization hours, coal-fired power plants have reduced profits or even lost money. Some power plants have begun to blend economical coals with high moisture content and low calorific value. [0003] The primary air temperature at the outlet of the air preheater of the bituminous coal-fired...

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Problems solved by technology

[0003] The primary air temperature at the outlet of the air preheater of the bituminous coal-fired boiler unit is generally designed at 280°C-320°C. To meet the drying demand, when the cold air door of the coal mill is fully closed, the drying capacity of the hot primary air is still insufficient, resulting in insufficient drying output of the coal mill, which affects the load capacity of the boiler

[0004] In order to increase the drying output of the coal mill, it can be appropriately alleviated by increasing the primary air volume, but it cannot be solved fundamentally. Moreover, the primary air rate of the boiler is too high and the secondary air rate is low, resulting in poor combustion air distribution in the furnace. A series of problems, such as overheating of the heating surface, high power consumption of the primary fan, and increased wear of the primary air duct, seriously affect the safe and stable operation of the unit

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