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CN-122015080-A - Ultra-low load stable combustion system and method for pulverized coal boiler

CN122015080ACN 122015080 ACN122015080 ACN 122015080ACN-122015080-A

Abstract

The invention discloses an ultralow-load stable combustion system and method of a pulverized coal boiler, comprises a pulverized coal concentration separator device, an oxygen preparation device, an oxygen storage tank, a heater, a concentrated pulverized coal burner, a light pulverized coal burner and an oxygen-enriched combustion-supporting air nozzle. The inlet of the pulverized coal concentration separator device is connected with a primary air pulverized coal feeding pipeline, the concentrated powder outlet of the pulverized coal concentration separator device is connected with a concentrated pulverized coal burner through a first pipeline, and the dilute powder outlet of the pulverized coal concentration separator device is connected with a dilute pulverized coal burner through a second pipeline; the oxygen preparation device is connected with an oxygen storage tank, the oxygen storage tank is connected with a heater, and the heater is connected with an oxygen-enriched combustion-supporting air nozzle arranged above the concentrated coal powder burner. The method comprises the steps of separating primary air into concentrated coal powder and light coal powder, sending the concentrated coal powder into a concentrated coal powder burner, sending the light coal powder into a light coal powder burner, preparing high-concentration oxygen, heating, spraying the high-concentration oxygen above the concentrated coal powder burner, and maintaining stable combustion when the load of a boiler is lower than 20%. The invention realizes continuous and stable combustion of the load of the boiler below 20 percent.

Inventors

  • XU YINGHUI
  • LIU KAI
  • NIU QINGDE
  • ZHANG YUE
  • ZHANG CHANG

Assignees

  • 中节环立为（武汉）能源技术有限公司

Dates

Publication Date
20260512
Application Date
20260306

Claims (10)

  1. 1. An ultra-low load stable combustion system of a pulverized coal boiler, which is characterized by comprising: the inlet of the pulverized coal concentration separator device (2) is connected with the primary air powder feeding pipeline (1) and is used for separating pulverized coal in primary air into concentrated pulverized coal and dilute pulverized coal; An oxygen production device (9) for producing high-concentration oxygen; An oxygen storage tank (10) connected to the oxygen production device (9) for storing oxygen; A heater (12) connected to the oxygen tank (10) for heating oxygen; the concentrated pulverized coal burner (6) is connected with a concentrated pulverized coal outlet (23) of the pulverized coal concentration separator device (2) through a first pipeline (3); The light coal powder burner (7) is connected with a light coal powder outlet (22) of the coal powder concentration separator device (2) through a second pipeline (4); The oxygen-enriched combustion-supporting air nozzle (8) is designed into a whole with the burner combustion-supporting secondary air nozzle, is connected with the heater (12) and is arranged above the concentrated coal powder burner (6) and is used for spraying the heated pure oxygen and the heated secondary air to improve the oxygen quantity and the temperature of the combustion-supporting secondary air adjacent to the burner, and the oxygen concentration of the combustion-supporting secondary air is adjusted through the valve (14) arranged on the secondary air channel and the pure oxygen pipeline adjusting valve (13) corresponding to the valve to improve the combustion-supporting capability.
  2. 2. The pulverized coal boiler ultra-low load stable combustion system according to claim 1, characterized in that the pulverized coal concentrating separator device (2) comprises: A primary air inlet connecting pipe (21), a concentrated powder outlet (23), a light powder outlet (22), a separation elbow (24), a separator outer cylinder (25), a separator inner cylinder (26) and an arc-shaped guide plate (27); the primary air inlet connecting pipe (21) and the separating elbow (24) are eccentrically arranged; the bending angle of the separation elbow (24) is 45-90 degrees.
  3. 3. The ultra-low load stable combustion system of pulverized coal boiler according to claim 2, characterized in that the separator inner cylinder (26) is parallel but not collinear with the center line of the separator outer cylinder (25).
  4. 4. The ultra-low load stable combustion system of the pulverized coal boiler according to claim 2, wherein the bending radius of the separation elbow (24) is 1.25-1.5 times of the radius of the outer cylinder (25) of the separator.
  5. 5. The ultra-low load stable combustion system of pulverized coal boiler according to claim 2, characterized in that the ratio of the maximum spacing to the minimum spacing between the separator inner cylinder (26) and the outer cylinder (25) is 2:1.
  6. 6. The ultra-low load stable combustion system of the pulverized coal boiler according to claim 2, characterized in that the arc-shaped guide plate (27) is connected with the inner cylinder (26) of the separator, wherein the inner side of the separation elbow (24) has the same bending radius but is not concentric.
  7. 7. The ultra-low load stable combustion system of the pulverized coal boiler according to claim 1 is characterized in that the primary air powder feeding pipeline (1) is provided with 4-6 layers, two layers of primary air powder feeding pipelines (1) are provided with pulverized coal concentration separators (2), and a second pipeline (4) connected with a concentration powder outlet (22) is provided with an electric adjustable shrinkage cavity (5).
  8. 8. The ultra-low load stable combustion system of the pulverized coal boiler according to claim 1, wherein an electric regulating valve (11) is arranged on a pipeline between the oxygen storage tank (10) and the heater (12), and the heater (12) is an explosion-proof heater.
  9. 9. The ultra-low load stable combustion system of the pulverized coal boiler according to claim 1, wherein the lean pulverized coal burner (7) is arranged separately from the rich pulverized coal burner (6), and the pure oxygen combustion-supporting air nozzles (8) are uniformly arranged above the rich pulverized coal burner (6).
  10. 10. An ultra-low load stable combustion method for a pulverized coal boiler, which is applied to a system as claimed in any one of claims 1 to 9, and is characterized by comprising the following steps: S1, introducing primary air into a pulverized coal concentration separator device (2) to separate into concentrated pulverized coal and dilute pulverized coal; S2, feeding the concentrated coal powder into a concentrated coal powder burner (6), and feeding the light coal powder into a light coal powder burner (7); S3, preparing high-concentration oxygen through an oxygen preparation device (9), and storing the high-concentration oxygen in an oxygen storage tank (10); s4, after the oxygen is heated by a heater (12), spraying the heated pure oxygen and hot secondary air, and improving the oxygen content and temperature of the combustion-supporting secondary air adjacent to the burner; and S5, when the boiler load is lower than 20%, the stable combustion of the concentrated pulverized coal burner (6) is maintained, and the ultra-low load stable combustion is realized.

Description

Ultra-low load stable combustion system and method for pulverized coal boiler Technical Field The invention relates to the technical field of pulverized coal boiler combustion, in particular to an ultralow-load stable combustion system and method for a pulverized coal boiler under a deep peak-shaving working condition. Background In recent years, with the development of new energy power generation technology driven by China, the proportion of clean energy sources such as wind power, photovoltaic, hydropower, nuclear power and the like in an electric power structure rises year by year, the utilization hours of a thermal power unit continuously decline, and partial load operation becomes normal. Meanwhile, in order to ensure safe and stable operation of the power grid, particularly under the condition of large fluctuation of new energy power generation output, a large thermal power generating unit is required to have stronger deep peak regulation capability so as to adapt to the load change requirement of the power grid. One of the key technical difficulties in realizing deep peak shaving of coal-fired units is the stable combustion capability under low load. When the boiler load is reduced to below 30% or even below 20%, the hearth temperature is obviously reduced, the coal powder is difficult to catch fire, the flame stability is poor, flameout or unstable combustion is easily caused, and fire or explosion accidents of the hearth can be caused when the flame stability is serious, so that the safe operation of the unit is threatened. The traditional low-load stable combustion technology such as micro-oil ignition, plasma ignition and the like improves the ignition capability to a certain extent, but under the condition of ultralow load (such as below 20 percent), continuous and stable combustion is still difficult to maintain, and the problems of complex system, high operation cost, poor adaptability to coal quality and the like exist. Therefore, the invention provides the ultralow-load stable combustion system and the ultralow-load stable combustion method for the pulverized coal boiler based on the combination of pulverized coal concentration separation and oxygen-enriched combustion supporting, which are used for remarkably improving the combustion stability under low load by improving the concentration of pulverized coal entering a combustor, the concentration of combustion supporting wind oxygen and the temperature on the premise of not changing the main body structure and the pulverizing system of the existing boiler, so that the continuous and stable operation of the boiler under the load of below 20 percent is realized. Disclosure of Invention The invention aims to overcome the defects of poor combustion stability and easy flameout of a boiler in ultralow-load operation in the prior art, and provides an ultralow-load stable combustion system and method for a pulverized coal boiler, which realize continuous stable combustion under the load of below 20 percent by a technical means of combining pulverized coal concentration and separation with oxygen-enriched combustion supporting. In order to achieve the above purpose, the present invention provides the following technical solutions: An ultra-low load stable combustion system of a pulverized coal boiler, comprising: the inlet of the pulverized coal concentration separator device is connected with a primary air powder conveying pipeline and is used for separating pulverized coal in primary air into concentrated pulverized coal and dilute pulverized coal; An oxygen preparation device for preparing high-concentration oxygen; The oxygen storage tank is connected with the oxygen preparation device and is used for storing oxygen; the heater is connected with the oxygen storage tank and is used for heating oxygen; The concentrated coal powder burner is connected with a concentrated coal powder outlet of the coal powder concentrating separator device through a pipeline; The light coal powder burner is connected with a light coal powder outlet of the coal powder concentration separator device through a pipeline; The oxygen-enriched combustion-supporting air nozzle is designed into a whole with the combustion-supporting secondary air nozzle of the burner, is connected with the heater, is arranged above the concentrated pulverized coal burner and is used for spraying heated pure oxygen and hot secondary air, so that the oxygen content and the temperature of the combustion-supporting secondary air adjacent to the burner are improved, and the oxygen concentration of the combustion-supporting secondary air is regulated through a regulating valve arranged on the secondary air channel and a pure oxygen pipeline regulating valve corresponding to the regulating valve, so that the combustion-supporting capacity is improved. Further, the pulverized coal concentration separator device comprises: The primary air inlet is connected with the pipe, the separating elbow, the ou