Search

CN-121977222-A - Powder preparation system and method suitable for medium-speed coal mill

CN121977222ACN 121977222 ACN121977222 ACN 121977222ACN-121977222-A

Abstract

The invention relates to the technical field of boiler transformation, in particular to a pulverizing system and a pulverizing method suitable for a medium-speed coal mill, wherein an outlet of the coal mill is divided into two paths, one path adopts direct-blowing pulverizing, the powder is directly supplied to a combustor to participate in combustion, and the other path adopts storage-type pulverizing, and the powder is stored after being separated by an air-powder separator; and at high load, the storage side rapidly supplements the powder for the boiler combustion, maintains the stable proportion of the air powder in the hearth, breaks through the limitation of the output of a pulverizing system on the variable load rate, simultaneously, the air-powder separator separates out the exhaust gas with the pulverized coal to remove dust, and the filtered fine pulverized coal is stored and participates in combustion when deep peak regulation is needed, thereby not only realizing the ladder utilization of the pulverized coal of the ventilation air, but also preventing the ventilation air from entering the hearth to cause combustion fluctuation. Solves the problem that the existing pulverizing system is difficult to consider the low-load stable operation and the stable combustion of the boiler during the deep peak shaving.

Inventors

  • MA WEIWEI
  • ZHOU KE
  • ZHANG PENG
  • LI MINGHAO
  • ZHOU JIE
  • CHENG RUISHEN
  • WANG YANZHI
  • YAN KE
  • LI YONG

Assignees

  • 西安热工研究院有限公司
  • 华能嘉祥发电有限公司

Dates

Publication Date
20260505
Application Date
20260327

Claims (10)

  1. 1. The coal pulverizing system suitable for the medium-speed coal pulverizer is characterized by comprising a coal feeder (4), wherein a coal feeding port of the coal feeder (4) is connected with the coal pulverizer (1), and the coal pulverizer (1) and the coal feeder (4) are both connected with a primary air duct (6) of a boiler; The coal dust outlet of the coal mill (1) is divided into two paths, one path is connected with a burner (18), the output end of the burner (18) is connected with a boiler furnace, the other path is sequentially connected with a wind-powder separator (9) and a coal storage bin (10), the coal dust outlet of the coal storage bin (10) is connected with the burner (18), the ventilation air outlet of the wind-powder separator (9) is connected with a cloth bag dust remover (15), the dust removing opening of the cloth bag dust remover (15) is connected with a fine coal powder bin (20), and the fine coal powder bin (20) is connected with a coal feeder (4).
  2. 2. The pulverizing system adapted to a medium speed coal pulverizer according to claim 1, wherein a centrifugal fan (11) is arranged between the wind-powder separator (9) and the bag-type dust collector (15), and a centrifugal fan outlet adjusting door (12) is arranged between the centrifugal fan (11) and the bag-type dust collector (15).
  3. 3. The milling system adapted to medium speed coal mills according to claim 1, characterized in that a bag house feeder (19) is arranged between the fine coal bin (20) and the coal feeder (4).
  4. 4. The coal pulverizing system adapted to the medium speed coal pulverizer according to claim 1, wherein a coal powder feeder (13) and a wind powder mixer (14) are sequentially arranged between the coal storage bin (10) and the burner (18), an air inlet of the wind powder mixer (14) is connected with a primary air duct (6) of the boiler, and an air inlet of the wind powder mixer (14) is provided with a wind powder mixer inlet regulating door (16).
  5. 5. The milling system adapted to medium speed coal mills according to claim 4, characterized in that a wind-powder mixer outlet distribution door (17) is provided between the wind-powder mixer (14) and the burner (18).
  6. 6. The coal pulverizing system adapted to medium speed coal pulverizer as defined in claim 1, wherein the coal pulverizer (1) coal pulverizer outlet is provided with a coal pulverizer separator (5).
  7. 7. The milling system adapted to medium speed coal mills according to claim 1, characterized in that a coal mill outlet to burner adjustment door (7) is provided between the coal mill (1) and the burner (18).
  8. 8. The milling system adapted to medium speed coal mills according to claim 1, characterized in that a coal mill outlet powder storage door (8) is arranged between the coal mill (1) and the wind-powder separator (9).
  9. 9. The coal pulverizing system adapted to a medium speed coal pulverizer as defined in claim 1, wherein the primary air inlet of the coal pulverizer (4) is provided with a coal pulverizer sealing door (3), and the primary air inlet of the coal pulverizer (1) is provided with a coal pulverizer primary air inlet door (2).
  10. 10. A coal pulverizing method using the coal pulverizing system adapted to the medium speed coal pulverizer as defined in any one of claims 1 to 9, comprising: when deep peak regulation is not needed, the coal feeder (4) feeds coal, and the pulverized coal ground by the coal mill (1) is sent to the air-powder separator (9) for air-powder separation; the coal dust separated by the wind-powder separator (9) is stored in a coal storage bin (10), and the ventilation air methane separated by the wind-powder separator (9) is sent to a bag-type dust remover (15) for dust removal; Releasing ventilation air methane meeting emission standards after dust removal, and storing coal dust filtered in the dust removal process of a bag-type dust remover (15) in a fine coal dust bin (20) to finish powder preparation; When deep peak regulation is needed, the pulverized coal in the coal storage bin (10) is firstly sent to the burner (18) to participate in combustion, meanwhile, the fine powder stored in the fine pulverized coal bin (20) and raw coal are fed to the coal mill (1) through the coal feeder (4), and the pulverized coal ground by the coal mill (1) is sent to the boiler hearth through the burner (18) to participate in combustion, so that powder making is completed.

Description

Powder preparation system and method suitable for medium-speed coal mill Technical Field The invention relates to the technical field of boiler transformation, in particular to a pulverizing system and method suitable for a medium-speed coal mill. Background In the great background of the accelerated transformation of global energy structures, the rapid development of clean energy presents unprecedented challenges to the traditional thermal power industry. With the continuous increase of the installed capacity of renewable energy sources such as wind energy, solar energy and the like, the inherent intermittence and fluctuation of the renewable energy sources bring great pressure to the stable operation of an electric power system. The grid requires more flexible regulation capability to balance supply and demand, ensuring the safety and reliability of power supply. In this context, how to improve flexibility through technical transformation in a thermal power plant is a focus of industry attention. The subcritical coal-fired generator set is taken as an important component of the thermal power industry, has huge installed capacity, and has about 30% higher energy storage capacity than that of a supercritical generator set of the same scale. The unit has remarkable advantages in the aspect of quick response to load change, and the drum furnace technology enables the energy storage capacity to be high, and can convert stored energy into electric energy for output in a short time. Along with the deep transformation of energy, how to further improve the flexibility of the energy transformation system so as to better adapt to the requirements of new energy access and power grid peak shaving becomes the key of the technical transformation of subcritical units. The prior art is mainly developed around key links such as a combustion system, a steam turbine system, a powder making system and the like, and aims to improve the flexibility and the operation efficiency of the unit through the technology. The modification of the coal pulverizing system is realized by improving the economy, the reliability and the adaptability to different coal types and loads of the coal pulverizing system, so that the stability and the efficiency of boiler combustion can be improved, the capability of the thermal power plant for treating various coal quality and load conditions can be increased, and meanwhile, the safety and the stability of operation and the energy conservation and emission reduction effects are improved. This means that by these technical improvements, it is possible to help the thermal power plant to better cope with the changing power demand, but also to achieve the environmental objectives and reduce the energy consumption. The medium-speed coal mill is coal milling equipment with the working rotation speed of 50-300 r/min, is widely applied to industries such as electric power, metallurgy, building materials, chemical industry and the like, and particularly plays an important role in a coal dust preparation system of a thermal power plant. The medium-speed coal mill drives the millstone to rotate through the motor, and raw coal enters the millstone from the central coal dropping pipe. Under the action of centrifugal force, raw coal is thrown between a grinding roller and a grinding disc, and crushed into coal dust under the extrusion and grinding actions. Simultaneously, hot air enters the coal mill from the side part, and the coal dust is synchronously dried in the crushing process. The air flow carries the pulverized coal to rise to the separator, coarse particles return to the millstone for regrinding, and qualified fine powder is sent into the boiler by the air flow for combustion. However, in the practical application process, when the peak shaving requirement is increased, the existing pulverizing system for the medium-speed coal mill has the problem of insufficient adjustment flexibility, and because the lowest stable combustion load of the original design burner is large, the coal mill has to be frequently started and stopped to adapt to load change when deep peak shaving operation is performed, so that equipment abrasion and maintenance cost are increased, and the increase of the number of fire extinguishment times of the boiler is caused due to unstable combustion. In order to solve the problem, the Chinese patent application with the authority of CN119879228B discloses a pulverizing system, a pulverizing method and a boiler of an external pulverizing bin, wherein an A side coarse powder separator is arranged on one side of a coal mill, a B side coarse powder separator is arranged on the other side of the coal mill, pulverized coal of the A side coarse powder separator sequentially enters the A side burner through a cyclone separator, a wind locking discharger and a wind powder mixer, the pulverized coal of the B side coarse powder separator directly enters the burner to realize two different operation m