WO2021043241A1 - 燃烧器底置煤粉锅炉及其控制方法 - Google Patents

燃烧器底置煤粉锅炉及其控制方法 Download PDF

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Publication number
WO2021043241A1
WO2021043241A1 PCT/CN2020/113400 CN2020113400W WO2021043241A1 WO 2021043241 A1 WO2021043241 A1 WO 2021043241A1 CN 2020113400 W CN2020113400 W CN 2020113400W WO 2021043241 A1 WO2021043241 A1 WO 2021043241A1
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Prior art keywords
secondary air
furnace
burner
pipe
internal
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PCT/CN2020/113400
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English (en)
French (fr)
Inventor
朱建国
李百航
李诗媛
高鸣
满承波
吕清刚
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中国科学院工程热物理研究所
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Priority to US17/640,636 priority Critical patent/US20230022074A1/en
Publication of WO2021043241A1 publication Critical patent/WO2021043241A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
    • F23C5/08—Disposition of burners
    • F23C5/10—Disposition of burners to obtain a flame ring
    • F23C5/12—Disposition of burners to obtain a flame ring for pulverulent fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
    • F23C5/08—Disposition of burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/18—Details; Accessories
    • F23C10/20—Inlets for fluidisation air, e.g. grids; Bottoms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C1/00—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air
    • F23C1/12—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air gaseous and pulverulent fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C7/00—Combustion apparatus characterised by arrangements for air supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/10007—Spouted fluidized bed combustors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Definitions

  • the embodiments of the present invention relate to the field of boilers, in particular to a pulverized coal boiler and a control method thereof.
  • Boiler vibration risk the main reason is the deterioration of pulverized coal combustion stability and the continuous fluctuation of pressure in the furnace, especially during low-load operation, the temperature level in the furnace is low, the flame of pulverized coal combustion cannot continue to spread, and the risk of boiler vibration Increase
  • the original NOx emission level of pulverized coal combustion is high: the original NOx emission level is more than 200mg/m 3 , the tail denitrification cost is high, and there is a risk of secondary pollution.
  • the mainstream industrial pulverized coal boilers mainly include horizontal pulverized coal boilers and vertical pulverized coal boilers. Compared with horizontal pulverized coal boilers, the flow field in vertical pulverized coal boilers is easier to organize and the boiler has higher thermal efficiency.
  • Chinese patent ZL201710425369.0 discloses a vertical pulverized coal boiler with a burner at the bottom, which uses a secondary air distribution pipe arranged on the entire cross section of the bottom of the furnace to provide secondary air.
  • the air supply is even and almost There is no entrainment and backflow, and the speed difference across the cross section of the furnace is very small, so the dispersed air and powder mixture flows upward as a whole, thus changing the conventional air-drum powder combustion method.
  • the invention realizes that the air-powder mixture flows upward and horizontally in the entire furnace space as a whole without a backflow zone in the furnace, avoids the accumulation and agglomeration of pulverized coal particles in the furnace, and improves the operation stability of the system.
  • the present invention provides a pulverized coal boiler with a bottom burner, including:
  • At least one burner is arranged at the bottom of the furnace, each burner has a burner nozzle, through the burner nozzle, primary air carries pulverized coal upward into the furnace;
  • the secondary air distribution device is arranged at the bottom of the furnace around the burner and is used to inject secondary air upwards,
  • the secondary air distribution device includes an internal secondary air distribution device and an external secondary air distribution device;
  • the internal secondary air distribution device includes an internal secondary air header and an internal secondary air pipe.
  • the internal secondary air pipe is connected to the internal secondary air header and is provided with a plurality of internal secondary air headers located in the furnace.
  • a wind outlet, at least a part of the inner secondary air outlets among the plurality of inner secondary air outlets are arranged adjacent to the burner nozzle;
  • the external secondary air distribution device includes an external secondary air header and an external secondary air pipe.
  • the external secondary air pipe is connected to the external secondary air header and is provided with a plurality of external secondary air boxes located in the furnace. Wind vent
  • the inner secondary air header is independent of the outer secondary air header.
  • the inner secondary air pipe is an annular pipe arranged around the burner nozzle.
  • the inner secondary air header is arranged below the burner nozzle adjacent to the burner nozzle or arranged around the burner nozzle.
  • the outer secondary air pipes are arranged parallel to each other or extend opposite to each other in the axial direction.
  • the inner secondary air pipe is provided with branch pipes, the branch pipes extend from the inner secondary air pipe, and the at least a part of the inner secondary air outlets are respectively arranged in the branch pipes.
  • the inner secondary air pipe includes two inner secondary air pipes respectively arranged on both sides of the burner nozzle; the branch pipe is arranged between the two inner secondary air pipes and the inner secondary air pipe The extension direction is located on both sides of the burner nozzle.
  • each inner secondary air pipe is provided with two branch pipes, and the inner secondary air outlets on the four branch pipes of the two inner secondary air pipes are arranged around the burner nozzle; or two branch pipes It is connected between the two inner secondary air pipes, the burner nozzle is located between the two branch pipes, and the inner secondary air outlet on the two branch pipes is arranged around the burner nozzle.
  • the inner secondary air pipe and the outer secondary air pipe are arranged parallel to each other.
  • the boiler further includes an air supply control device for controlling the air supply ratio of the internal secondary air to the external secondary air. Further optionally, the air supply control device separately controls the internal secondary air and the external secondary air.
  • the height of the internal secondary air outlet is lower than the height of the burner nozzle.
  • the air outlet angle of the internal secondary air outlet is inclined toward the burner nozzle.
  • the burner is a preheating burner.
  • the invention also relates to a control method of a pulverized coal boiler, including the steps:
  • the secondary air distribution device arranged around the burner at the bottom of the furnace injects the secondary air upwards into the furnace
  • the secondary air distribution device includes an internal secondary air distribution device and an external secondary air distribution device;
  • the internal secondary air distribution device includes an internal secondary air header and a burner nozzle set adjacent to the burner
  • the outer secondary air distribution device includes an outer secondary air header and an outer secondary air pipe, the inner secondary air header is independent of the outer secondary air header;
  • the method also includes the step of separately controlling the air volume entering the inner secondary air header and the outer secondary air header.
  • the method includes the steps of: controlling the equivalent ratio of the internal secondary air to 0.1 to 0.3; and controlling the equivalent ratio of the external secondary air to 0.3 to 0.6, and the secondary air of the external secondary air and the internal secondary air
  • the total equivalent ratio is 0.7 to 0.9.
  • the method further includes the step of increasing the air volume of the inner secondary air header to strengthen the mixing of the secondary air with the pulverized coal carried by the primary air of the burner.
  • the method further includes the step of reducing the proportion of the internal secondary air and increasing the proportion of the external secondary air, so as to reduce the temperature of the furnace center.
  • Fig. 1 is a schematic front view of a pulverized coal boiler according to an exemplary embodiment of the present invention
  • Figure 2 is a schematic structural diagram of a pulverized coal boiler according to an exemplary embodiment of the present invention, showing a secondary air distribution device;
  • Fig. 3 is a schematic structural diagram of a pulverized coal boiler according to an exemplary embodiment of the present invention, showing a secondary air distribution device;
  • Figure 4 is a partial schematic front view of the pulverized coal boiler in Figure 3;
  • Figure 5 is a schematic structural diagram of a pulverized coal boiler according to an exemplary embodiment of the present invention, showing a secondary air distribution device and two burner nozzles;
  • Fig. 6 is a schematic structural diagram of an expansion shield according to an exemplary embodiment of the present invention.
  • Figures 1 to 5 show schematic diagrams of a pulverized coal boiler according to an exemplary embodiment of the present invention.
  • the vertical pulverized coal boiler with the burner at the bottom includes: the furnace 11; the burner 31, which is arranged at the bottom of the furnace 11; the burner nozzle 32, which communicates with the burner 31, extends upward from the outside of the furnace bottom It enters the inner cavity of the furnace and is suitable for passing the mixture of primary air and pulverized coal into the furnace 11; the secondary air header 21 is arranged at the bottom of the furnace 11 or the side near the bottom; it communicates with the secondary air header and is connected to the secondary air header.
  • the secondary air pipe 22 extending from the box to the inside of the furnace, each secondary air pipe is provided with a plurality of hoods 23,
  • the secondary air pipe is divided into an inner secondary air pipe 22a and an outer secondary air pipe 22b.
  • the inner secondary air pipe 22a is the secondary air pipe adjacent to the burner nozzle 32, and the rest are the outer secondary air pipe 22b.
  • the inner and outer secondary air pipes are respectively communicated with different secondary air headers.
  • the inner secondary air header and the outer secondary air header are independent of each other, so that the air volume in the wind box can be individually controlled.
  • the burner nozzle 32 and the secondary air duct 23 do not overlap.
  • the air outlet on the secondary air pipe may be a direct air outlet, or may be provided with a hood 23 as described above.
  • the secondary air outlets are approximately evenly distributed at the bottom of the furnace.
  • the furnace is also provided with a tertiary air inlet 13. It is arranged on the side wall in the middle of the furnace 11 and is suitable for passing tertiary air into the furnace 11 to burn out the fuel.
  • the tertiary air nozzles can be arranged oppositely or tangentially on the front and rear walls of the furnace.
  • the burner nozzle 32 may be one or more.
  • the furnace 11 may be a square columnar structure, and the side walls are enclosed by four membrane walls, including a front wall, a rear wall, a left side wall, and a right side wall.
  • the furnace 11 may also be a cylindrical structure or other columnar structures.
  • the vertical pulverized coal boiler includes a furnace 11, which provides a space for fuel combustion; a burner 31, arranged at the bottom of the furnace 11; a burner nozzle 32, which communicates with the burner 31, extends upward from the outside of the furnace bottom to enter
  • the inner cavity of the furnace is suitable for passing the mixture of primary air and pulverized coal into the furnace 11; the secondary air header 21 placed outside the lower part of the furnace 11;
  • the secondary air pipe close to the burner nozzle is the inner secondary air pipe 22a, and the rest are the outer secondary air pipe 22b; the inner secondary air pipe 22a is arranged close to the combustion A branch pipe 24 connected to the inner secondary air pipe 22a on one side of the nozzle 32; a hood 23 provided on the secondary air pipe 22 and the branch pipe 24.
  • One of the secondary air headers is only connected to the inner secondary air pipe 22a, and the other is connected to the outer secondary air pipe 22b.
  • the secondary air pipe 22 can adopt the form of passing through the furnace as shown in FIG. 2.
  • the intersection of the end of the secondary air pipe 22 near the secondary air header 21 and the side wall of the boiler 11 can be fixedly connected and sealed by welding or other methods.
  • One end is overlapped with the boiler 11 or connected in other non-fixed ways;
  • the expansion shield 12 is arranged outside the furnace, and surrounds the secondary air pipe passing through the furnace and forms a sealed expansion shield 12 in the furnace (see Figure 6). 12 provides sufficient expansion space for the secondary air pipe, which can be sealed by welding or the like to prevent gas from entering or flowing out of the furnace 11 from the expansion shield 12.
  • the secondary air duct 22 may also extend from the bottom of the furnace into the furnace, bend horizontally, and continue to extend in the horizontal direction, wherein the length of the secondary air duct 22 extending horizontally is slightly smaller than the side length of the furnace section.
  • the height of the air outlet of the hood 23 provided on the inner secondary air pipe 22a and the branch pipe 24 on the horizontal plane is lower than the outlet of the burner nozzle 32, which is beneficial to reduce the secondary air The effects of fire.
  • the number of secondary air ducts 22, the diameter/section width of the secondary air duct, and the air outlet section size of the air cap provided on the secondary air duct can be determined according to the size of the cross-sectional area of the furnace 11 and the resistance calculation.
  • FIGS 3 and 4 show another exemplary embodiment of the present invention.
  • the boiler includes three secondary air headers 21, of which one secondary air header 21 is only connected to the inner secondary air pipe 22a through a rigid pipe, and the inner secondary air pipe 22a is a "return".
  • the outer secondary air pipes basically cover the entire furnace bottom section and leave an expansion gap between each other.
  • the two external secondary air headers and the two connected sets of external secondary air pipes are at the same height.
  • the inner secondary air duct and the outer secondary air duct do not overlap.
  • by separately controlling the air volume of the secondary air header connected to the inner secondary air pipe 22a and the outer quadratic square pipe 22b separate control of the secondary air volume close to and away from the burner nozzle 3 is achieved.
  • the inner secondary air duct 22a of the "return"-shaped structure may also be a circular ring structure.
  • the air outlet angle of the inner secondary air pipe 22a and/or the air cap 23 on the branch pipe 24 can be biased toward the burner nozzle, thus enhancing the mixing of the internal secondary air and the fuel carried by the primary air .
  • each preheating burner nozzle is equipped with an internal secondary air that is blended with preheating fuel and is controllable, and an external secondary air is set outside the internal secondary air. wind.
  • the number of inner secondary air chambers is the same as the number of nozzles of the preheating burner, and the number of outer secondary air chambers may be only one or multiple, all of which fall within the protection scope of the present invention.
  • the air distribution structure of the secondary air can be flexibly adjusted according to the number of burners and the number of burner nozzles.
  • the primary air and preheating fuel are sprayed from the nozzle 32 of the preheating burner, and the injection speed is between 10-30m/s.
  • the internal secondary air is sprayed from the internal secondary air distribution device 4, and the internal secondary air is injected The speed is between 10 and 30m/s.
  • the inner secondary air closely surrounds the periphery of the preheating burner nozzle to speed up the mixing with the primary air.
  • the outer secondary air can be sprayed out by the distributed hood 23, and the outer secondary air exits the air.
  • Uniform, full-section air supply mode can delay the rapid mixing and reaction of a large amount of secondary air and preheated fuel, weaken the high temperature area of preheated fuel combustion, and at the same time, supply secondary air at the bottom to prevent coal particles from being deposited at the bottom of the furnace. Deposition.
  • the speed of the three air jets in the furnace is related to the section of the furnace, and is generally between 10 and 20m/s.
  • the entire furnace below the tertiary air nozzle is a uniform reducing atmosphere, and above the tertiary air nozzle 13 is the burnout area.
  • the preheating fuel is a mixture of high-temperature coal gas and high-temperature coke.
  • the high-temperature gas is the gas produced by the reaction of pulverized coal and primary air during the preheating process of pulverized coal
  • the high-temperature coke is the solid matter converted after the reaction of pulverized coal during the preheating of pulverized coal.
  • the ratio of the internal secondary air is related to the composition of the preheated fuel, the temperature of the preheated fuel and the furnace temperature. If the preheated fuel gas has a high calorific value, the preheated fuel will ignite quickly. In order to control the heat release rate of the preheated fuel, the internal combustion heat can be reduced. The proportion of the secondary air or increase the injection speed of the internal secondary air. The equivalent ratio of the internal secondary air is generally between 0.1 and 0.3.
  • the external secondary air needs to be organically combined with the internal secondary air.
  • the internal secondary air mainly ensures the rapid ignition and stable combustion of the fuel.
  • the external secondary air provides combustion-supporting gas for the uniform combustion of the fuel in the entire space of the furnace to ensure the combustion share of the fuel.
  • the ratio of the external secondary air is higher than that of the internal secondary air, and the air volume ratio of the external secondary air to the internal secondary air can be controlled to be 5:1 ⁇ 2:1.
  • the total equivalent ratio of the secondary air can be controlled between 0.7 and 0.9.
  • the furnace temperature is controlled between 1000 and 1200°C to achieve stable, high-efficiency and low-nitrogen combustion of the preheated fuel.
  • the secondary air at the bottom of the furnace is provided with internal secondary air and external secondary air surrounding the nozzle of the preheating burner, and the air volume of the internal secondary air and the air volume of the external secondary air can be independently controlled.
  • the internal secondary air is the control air and regulating air for the stable combustion of the fuel
  • the external secondary air is the main air for fuel combustion, which has the dual functions of adjusting the furnace temperature and controlling the atmosphere in the furnace.
  • the entire furnace below the tertiary air nozzle is a reducing atmosphere, that is, the air equivalent coefficient below the tertiary air nozzle is less than 1.0.
  • the rapid mixing and contact of the preheating fuel and the secondary air can be realized, and the preheating fuel can be avoided due to the slow mixing of the preheating fuel with the secondary air or the cooling effect of the furnace water wall.
  • Hot fuel extinguishes or burns unsteadily and the amount of internal secondary air is related to the composition of the preheated fuel, the temperature of the preheated fuel and the furnace temperature.
  • the external secondary air is the main air used for fuel combustion. After the preheated fuel and the internal secondary air undergo gasification reaction, the furnace temperature will increase, and the gasified gas and ungasified coke will expand outward from the center.
  • the external secondary air contacts, because the entire section of the furnace bottom adopts a hood to supply air, the flow field in the furnace is uniform, and the material after the preheated fuel reacts with the internal secondary air reacts in the entire furnace space, and because of the air equivalent below the furnace tertiary air nozzle The ratio is less than 1.0, and there is no oxygen-rich atmosphere below the furnace tertiary air nozzle.
  • the precipitation of nitrogen-containing substances is strengthened.
  • the precipitated nitrogen-containing substances are uniformly reduced under the furnace tertiary air nozzle. In a neutral atmosphere, it is easy to convert to nitrogen, which reduces the nitrogen oxide emission level of the preheated fuel combustion.
  • the internal secondary air surrounds the preheated fuel
  • the internal secondary air can also be supplied in the form of a hood, which speeds up the mixing of the preheated fuel and the internal secondary air, and ensures the rapid ignition of the preheated fuel And stable combustion, the external secondary air ensures uniform flow field and composition in the furnace.
  • the main space of the furnace below the tertiary air nozzle of the furnace is a reducing atmosphere, and the local oxygen-enriched atmosphere is small, which reduces the nitrogen oxide emission level of the preheated fuel combustion.
  • the "inner” in the “internal secondary air” is relative to the “outer” in the “outer secondary air”.
  • the secondary air outlet connected to the air header is closer to the burner nozzle than the secondary air outlet connected to another separate secondary air header.
  • the outer secondary air outlets can be arranged in a decentralized manner, for example, they can be evenly distributed like a lattice as shown in the figure, or they can surround the inner two air outlets.
  • the annular arrangement of the secondary air distribution device(s) are all within the protection scope of the present invention.
  • the secondary air header may be arranged at the bottom of the furnace, and communicate with the secondary air pipe arranged in the lower part of the furnace through several upward pipes.
  • adjacent secondary air ducts that penetrate the furnace can share an expansion shield.
  • the secondary air pipe 22 is provided with air distribution holes instead of the hood, and the air distribution holes may be symmetrically arranged on the downward side of the secondary air pipe along the center line of the vertical direction of the secondary air pipe section. These are all within the protection scope of the present invention.
  • the present invention proposes a pulverized coal boiler with a bottom burner, including:
  • At least one burner is arranged at the bottom of the furnace, each burner has a burner nozzle, through the burner nozzle, primary air carries pulverized coal upward into the furnace;
  • the secondary air distribution device is arranged at the bottom of the furnace around the burner and is used to inject secondary air upwards,
  • the secondary air distribution device includes an internal secondary air distribution device and an external secondary air distribution device;
  • the internal secondary air distribution device includes an internal secondary air header and an internal secondary air pipe.
  • the internal secondary air pipe is connected to the internal secondary air header and is provided with a plurality of internal secondary air headers located in the furnace.
  • a wind outlet, at least a part of the inner secondary air outlets among the plurality of inner secondary air outlets are arranged adjacent to the burner nozzle;
  • the external secondary air distribution device includes an external secondary air header and an external secondary air pipe.
  • the external secondary air pipe is connected to the external secondary air header and is provided with a plurality of external secondary air boxes located in the furnace. Wind vent
  • the inner secondary air header is independent of the outer secondary air header.
  • the present invention also proposes a control method for a pulverized coal boiler, which includes the steps:
  • the secondary air distribution device arranged around the burner at the bottom of the furnace injects the secondary air upwards into the furnace
  • the secondary air distribution device includes an internal secondary air distribution device and an external secondary air distribution device;
  • the internal secondary air distribution device includes an internal secondary air header and a burner nozzle set adjacent to the burner
  • the outer secondary air distribution device includes an outer secondary air header and an outer secondary air pipe, the inner secondary air header is independent of the outer secondary air header;
  • the method also includes the step of separately controlling the air volume entering the inner secondary air header and the outer secondary air header.
  • the fuel such as preheating fuel
  • it can be quickly and timely mixed with the secondary air, which shortens the ignition time of the preheated fuel, strengthens the combustion stability of the preheated fuel, and avoids or reduces Preheated fuel ignition deflagration tendency and combustion process boiler vibration problems.
  • the advance conversion of nitrogenous substances in the blending of the preheated fuel and the internal secondary air is accelerated, and the main area below the tertiary air nozzle of the furnace
  • the local oxygen-enriched area is basically eliminated, the reduction degree of nitrogenous substances is increased, and the NOx emission level of the preheated fuel combustion is reduced.
  • the internal and external secondary air is separately controlled, that is, the secondary air is divided into zones, which can improve the flexibility of the boiler control, which is beneficial to strengthen the mixing of the fuel carried by the primary air and the secondary air and ensure the stability of ignition and combustion. , And help control the temperature distribution and flow field distribution in the furnace.

Abstract

一种燃烧器底置的煤粉锅炉及煤粉锅炉的控制方法。其中煤粉锅炉包括炉膛（11），至少一个底置燃烧器（31）和二次风布风装置。每个燃烧器（31）具有燃烧器喷口（32），一次风携带煤粉通过燃烧器喷口（32）向上进入炉膛（11），二次风布风装置围绕燃烧器（31）设置在炉膛（11）底部，用于向上喷射二次风。二次风布风装置包括内二次风布风装置和外二次风布风装置。内二次风布风装置包括内二次风集箱与内二次风管（22a）。内二次风管（22a）与内二次风集箱相连且设置有位于炉膛（11）内的多个内二次风出风口，至少一部分内二次风出风口邻近燃烧器喷口（32）布置。外二次风布置装置包括外二次风集箱与外二次风管（22b），外二次风管（22b）与外二次风集箱相连且设置有位于炉膛（11）内的多个外二次风出风口。内二次风集箱独立于外二次风集箱。

Description

燃烧器底置煤粉锅炉及其控制方法 技术领域
本发明的实施例涉及锅炉领域，尤其涉及煤粉锅炉及其控制方法。
背景技术
我国在用燃煤工业锅炉达46.7万台，年消耗原煤约7亿吨，占全国煤炭消耗总量的18％以上。工业锅炉是重要的热能动力设备，广泛应用于工厂动力、建筑采暖、人民生活等各个方面。2015年，国家能源局印发了《煤炭清洁高效利用行动计划(2015-2020)》，要大力推动高效煤粉工业锅炉技术发展和市场应用。
但现有燃煤工业锅炉存在如下技术缺陷：
(1)煤粉点火时刻存在爆燃倾向：主要原因是给入炉膛的煤粉多为冷煤粉，煤粉在炉膛内需要经历预热、挥发分析出和着火阶段，点火时刻炉膛温度偏低，点火时间长，增大爆燃倾向；
(2)锅炉存在振动风险：主要原因是煤粉燃烧稳定性恶化，炉内压力持续波动，特别是低负荷运行时，炉内温度水平偏低，煤粉燃烧的火焰不能持续传播，锅炉振动风险增大；
(3)煤粉燃烧的NOx原始排放水平高：NOx原始排放水平多在200mg/m 3以上，尾部脱硝费用较高，且存在二次污染风险。
主流的工业煤粉锅炉主要有卧式煤粉锅炉和立式煤粉锅炉两种，与卧式煤粉锅炉相比，立式煤粉锅炉炉内的流场更便于组织，锅炉热效率较高。
此外，中国专利ZL201710425369.0公开了一种燃烧器底置的立式煤粉锅炉，采用设置于炉膛底部的整个横截面上的二次风布风管来提供二次风，供风均匀，几乎不出现卷吸、回流，炉膛横截面上各处的速度差很小，因此形成弥散的风粉混合物整体向上流动，从而改变了常规的风包粉燃烧方式。该发明实现了风粉混合物在全炉膛空间内整体向上平推流动，炉膛 内不出现回流区，避免了煤粉颗粒在炉膛内积聚、结团，提高了系统运行稳定性。
但是，上述专利中存在二次风不易实现分区控制，炉膛温度和污染物控制手段较弱的问题。
发明内容
为缓解或解决煤粉锅炉上述问题中的至少一个方面，提出本发明。
根据本发明的实施例的一个方面，本发明提出一种燃烧器底置的煤粉锅炉，包括：
炉膛；
至少一个燃烧器，设置在炉膛底部，每个燃烧器具有燃烧器喷口，通过所述燃烧器喷口，一次风携带煤粉向上进入所述炉膛；
二次风布风装置，围绕所述燃烧器设置在炉膛底部，用于向上喷射二次风，
其中：
所述二次风布风装置包括内二次风布风装置和外二次风布风装置；
所述内二次风布风装置包括内二次风集箱与内二次风管，所述内二次风管与内二次风集箱相连且设置有位于炉膛内的多个内二次风出风口，所述多个内二次风出风口中的至少一部分内二次风出风口邻近所述燃烧器喷口布置；
所述外二次风布风装置包括外二次风集箱与外二次风管，所述外二次风管与外二次风集箱相连且设置有位于炉膛内的多个外二次风出风口；
所述内二次风集箱独立于外二次风集箱。
在一个实施例中，内二次风管为围绕燃烧器喷口设置的环形管。可选的，所述内二次风集箱在燃烧器喷口下方邻近燃烧器喷口设置或者围绕燃烧器喷口设置。可选的，外二次风管彼此之间平行布置或者在轴向上彼此相对延伸。
可选的，所述内二次风管设置有分支管，所述分支管自所述内二次风管延伸，且所述至少一部分内二次风出风口分别设置于所述分支管。
可选的，所述内二次风管包括分别设置于燃烧器喷口两侧的两个内二 次风管；分支管设置在两个内二次风管之间且在内二次风管的延伸方向上位于燃烧器喷口的两侧。进一步可选的，每一个内二次风管设置有两个分支管，两个内二次风管的四个分支管上的内二次风出风口围绕燃烧器喷口设置；或者两个分支管连接在两个内二次风管之间，燃烧器喷口位于所述两个分支管之间，且两个分支管上的内二次风出风口围绕燃烧器喷口设置。
可选的，所述内二次风管与所述外二次风管彼此平行布置。
可选的，所述锅炉还包括供风控制装置，用于控制内二次风与外二次风的供风比例。进一步可选的，所述供风控制装置对内二次风与外二次风分开控制。
可选的，在本发明的技术方案中，所述内二次风出风口的高度低于燃烧器喷口的高度。
可选的，在本发明的技术方案中，所述内二次风出风口的出风角度朝向燃烧器喷口倾斜。
可选的，所述燃烧器为预热燃烧器。
本发明还涉及一种煤粉锅炉的控制方法，包括步骤：
通过设置在炉膛底部的至少一个燃烧器，向炉膛内向上喷射煤粉燃料；和
通过围绕燃烧器设置在炉膛底部的二次风布风装置向炉膛内向上喷射二次风，
其中：
所述二次风布风装置包括内二次风布风装置和外二次风布风装置；所述内二次风布风装置包括内二次风集箱与邻近燃烧器的燃烧器喷口设置的内二次风管，所述外二次风布风装置包括外二次风集箱与外二次风管，所述内二次风集箱独立于外二次风集箱；且
所述方法还包括步骤：分别控制进入到内二次风集箱和外二次风集箱中的风量。
可选的，所述方法包括步骤：控制内二次风的当量比为0.1～0.3；和控制外二次风当量比为0.3～0.6，且外二次风与内二次风的二次风总当量比为0.7～0.9。
可选的，所述方法还包括步骤：提高内二次风集箱的风量以强化二次 风对燃烧器的一次风携带煤粉的掺混。
可选的，所述方法还包括步骤：降低内二次风比例且提高外二次风比例，以用于降低炉膛中心温度。
附图说明
以下描述与附图可以更好地帮助理解本发明所公布的各种实施例中的这些和其他特点、优点，图中相同的附图标记始终表示相同的部件，其中：
图1为根据本发明的一个示例性实施例的煤粉锅炉的示意性主视图；
图2为根据本发明的一个示例性实施例的煤粉锅炉的结构示意图，示出了二次风布风装置；
图3为根据本发明的一个示例性实施例的煤粉锅炉的结构示意图，示出了二次风布风装置；
图4为图3中的煤粉锅炉的局部示意性主视图；
图5为根据本发明的一个示例性实施例的煤粉锅炉的结构示意图，示出了二次风布风装置以及两个燃烧器喷口；
图6根据本发明的一个示例性实施例的膨胀防护罩的结构示意图。
具体实施方式
下面通过实施例，并结合附图，对本发明的技术方案作进一步具体的说明。在说明书中，相同或相似的附图标号指示相同或相似的部件。下述参照附图对本发明实施方式的说明旨在对本发明的总体发明构思进行解释，而不应当理解为对本发明的一种限制。
图1-图5示出了本发明的示例性实施例的煤粉锅炉的示意性图。
如图1-5所示，燃烧器底置的立式煤粉锅炉包括：炉膛11；燃烧器31，布置在炉膛11底部；燃烧器喷口32，与燃烧器31相通，从炉膛底部外侧向上延伸进入到炉膛内腔并适于将一次风和煤粉的混合物通入炉膛11内；二次风集箱21，布置在炉膛11底部或靠近底部的侧面；与二 次风集箱相通、由集箱向炉膛内部延伸的二次风管22，每个二次风管上设置多个风帽23，
其中：
所述二次风管分为内二次风管22a和外二次风管22b，内二次风管22a为与燃烧器喷口32紧邻的二次风管，其余为外二次风管22b，内、外二次风管分别与不同的二次风集箱相通。换言之，在本发明的实施例中，内二次风集箱与外二次风集箱彼此独立，以便于对风箱中的风量进行单独控制。
如本领域技术人员能够理解的，在炉膛11中部截面的俯视图中，燃烧器喷口32和二次风管23不重合。
如本领域技术人员能够理解的，二次风管上的出风口可以是直接出风喷口，也可以是如上所述的设置有风帽23。如本领域技术人员能够理解的，二次风出风口大致均匀的分布于炉膛底部。
在图1中，炉膛还设置有三次风入口13。其布置在炉膛11中部侧壁，适于向炉膛11内通入三次风，用于将燃料燃尽。三次风喷口可在炉膛前后墙呈对冲布置或四角呈切圆布置。
如图2-5中所示，燃烧器喷口32可为一个或多个。
炉膛11可为方形柱状结构，侧壁为四片膜式壁围合，包括前墙、后墙、左侧墙和右侧墙，炉膛也可为圆柱形结构或其他柱状结构。
下面参照附图示例性的具体描述本发明。
如图2所示，立式煤粉锅炉包括炉膛11，提供燃料燃烧的空间；燃烧器31，布置在炉膛11底部；燃烧器喷口32，与燃烧器31相通，从炉膛底部外侧向上延伸进入到炉膛内腔并适于将一次风和煤粉的混合物通入炉膛11内；置于炉膛11下部外侧的二次风集箱21；与二次风集箱相通的、自二次风集箱向炉膛内延伸的若干根二次风管22，其中，靠近燃烧器喷口的二次风管为内二次风管22a，其余为外二次风管22b；设置在内二次风管22a靠近燃烧器喷口32一侧并与内二次风管22a相连通的分支管24；设置在二次风管22和分支管24上的风帽23。其中一个二次风集箱仅与内二次风管22a相连，另一个与外二次风管22b相连，通过单独控制进入两个二次风集箱的风量，实现靠近和远离燃烧器喷口32的二次 风量的分别控制，从而实现锅炉内流场的优化。
二次风管22可采用如图2所示的贯穿炉膛形式，二次风管22靠近二次风集箱21的一端与锅炉11侧壁相交处可采用焊接或其他方式固定连接且密封，另一端与锅炉11搭接或采用其他非固定方式连接；设置在炉膛外部、将从炉膛穿出的二次风管包围并于炉膛形成密封的膨胀防护罩12(参见图6)，该膨胀防护罩12为二次风管提供充足的膨胀空间，可以采用焊接等方式密封，防止气体从该膨胀防护罩12进入或流出炉膛11。
二次风管22也可以从炉膛底部延伸进入炉膛后水平弯折，并继续沿水平方向延伸，其中，水平延伸的二次风管22长度略小于炉膛的截面边长。
在本发明的一个实施例中，设置在内二次风管22a和分支管24上的风帽23的出风口在水平面上的高度低于燃烧器喷口32的出口，如此有利于减少二次风对着火的影响。
可以根据炉膛11横截面积的大小，根据阻力计算，确定二次风管22的数目和二次风管的直径/截面宽度以及设置在二次风管上的风帽的出风口截面尺寸等。
图3和图4示出了本发明的另一个示例性实施例。在该实施例中，锅炉包括三个二次风集箱21，其中一个二次风集箱21通过一个刚性管道仅与内二次风管22a相连，所述内二次风管22a为“回”形结构，将燃烧器喷口32环绕在中间，如图3所示，另外两个二次风集箱21分别与两组外二次风管22b相连，两组外二次风管22b分别自炉膛边缘向炉膛中心延伸，并与另外一组外二次风管相靠近，外二次风管将整个炉底截面基本覆盖，并相互之间留有膨胀间隙。两个外二次风集箱及其连接的两组外二次风管处在同一高度。在俯视图中，内二次风管和外二次风管不相重合。在实际运行中，通过单独控制与内二次风管22a和外二次方管22b相连的二次风集箱的风量，实现靠近和远离燃烧器喷口3的二次风量的分别控制。
如本领域技术人员能够想到的，“回”形结构的内二次风管22a也可以为圆环形结构。
在本发明的一个实施例中，内二次风管22a和/或分支管24上的风帽23的出风角度可偏向燃烧器喷口，如此，强化内二次风与一次风携带燃 料的掺混。
如本领域技术人员能够想到的，在锅炉容量较大或其他必要的情况下，锅炉底部可以布置多个燃烧器喷口(对应一个或多个燃烧器)，如图5所示，炉膛设置了2个(也可更多个)预热燃烧器喷口，每个预热燃烧器喷口外围设置了加强与预热燃料掺混且可控的内二次风，内二次风外设置了外二次风。内二次风室数量与预热燃烧器喷口数量相同，外二次风室可仅为一个，也可以为多个，均在本发明的保护范围之内。二次风布风结构可以根据燃烧器数目、燃烧器喷口数目灵活调整。
下面说明根据本发明的示例性实施例的煤粉锅炉的操作或者运行。
一次风和预热燃料从预热燃烧器喷口32喷出，其喷射速度为10～30m/s之间，内二次风经从内二次风布风装置4喷出，内二次风喷射速度为10～30m/s之间，内二次风紧密围绕在预热燃烧器喷口外围，加快与一次风的掺混，外二次风可由分布的风帽23喷出，外二次风出风均匀，全截面供风方式可延缓大量二次风与预热燃料的快速掺混和反应，削弱预热燃料燃烧的高温区域，同时，底部供入二次风，可防止煤粉颗粒在炉底的沉积。
炉膛三次风喷射速度与炉膛断面有关，一般为10～20m/s之间。炉膛三次风喷口以下整体为均匀还原性气氛，三次风喷口13以上为燃尽区域。预热燃料为高温煤气和高温焦炭的混合物质，高温煤气是煤粉预热过程中煤粉与一次风反应转化生成的气体，高温焦炭是煤粉预热中煤粉反应后转化的固体物质。内二次风的比率与预热燃料成分、预热燃料温度和炉膛温度有关，若预热燃料煤气热值高，则预热燃料着火迅速，为控制预热燃料燃烧热量释放速率，可减少内二次风比例或提高内二次风喷射速度。内二次风的当量比一般为0.1～0.3之间。外二次风需要与内二次风有机组合，内二次风主要保证燃料的快速点火和稳定燃烧，外二次风为燃料在炉膛全空间内的均匀燃烧提供助燃气体，保障燃料的燃烧份额和热量释放，外二次风比例高于内二次风，外二次风外二次风与内二次风的风量之比可控制为5:1～2:1，内二次风和外二次风总当量比可控制为0.7～0.9之间。预热燃料燃烧过程中，控制炉膛温度在1000～1200℃之间，实现预热燃料的稳定、高效和低氮燃烧。
在上述实施例中，炉膛底部二次风设置了围绕预热燃烧器喷口的内二次风和外二次风，内二次风风量和外二次风风量均可单独控制。内二次风是燃料稳定燃烧的控制风和调节风，外二次风是燃料燃烧的主要用风，具有调整炉膛温度和控制炉内气氛的双重作用。炉膛三次风喷口以下整体为还原性气氛，即三次风喷口以下的空气当量系数小于1.0。
通过围绕预热燃烧器喷口的内二次风，可实现预热燃料与二次风的快速掺混和接触，避免预热燃料因与二次风掺混过慢或炉膛水冷壁的降温效果导致预热燃料熄火或燃烧不稳定，内二次风风量大小与预热燃料成分、预热燃料温度和炉膛温度有关。
外二次风是燃料燃烧的主要用风，预热燃料与内二次风发生气化反应后，炉膛温度升高，气化后的气体和未气化的焦炭等从中心向外扩展后与外二次风接触，因炉底整个断面采用风帽供风，炉内流场均匀，预热燃料与内二次风反应后的物质在全炉膛空间内反应，且由于炉膛三次风喷口以下空气当量比小于1.0，炉膛三次风喷口以下无富氧气氛，再结合预热燃料与内二次风反应过程中，强化了含氮物质的析出，析出的含氮物质在炉膛三次风喷口下整体均匀还原性气氛中，易于向氮气发生转化，降低了预热燃料燃烧的氮氧化物排放水平。
在本发明的实施例中，内二次风围绕在预热燃料外围，内二次风也可以风帽形式供风，加快预热燃料与内二次风的掺混，保障预热燃料的快速着火和稳定燃烧，外二次风保障炉内流场和组分均匀，炉膛三次风喷口以下炉膛主要空间为还原性气氛，局部富氧气氛小，降低预热燃料燃烧的氮氧化物排放水平。
一般情况下，提高内二次风比例，强化二次风与一次风携带的煤粉的掺混作用，可使煤粉着火迅速、稳定燃烧；炉膛中心温度偏高时(如达到燃料灰熔点温度)，可通过降低内二次风比例、提高外二次风比例的方式调整炉膛截面温度分布。
需要指出的是，在本发明中，“内二次风”中的“内”是相对于“外二次风”中的“外”而言，这里的“内”表示与一个单独的二次风集箱相连的二次风出风口比与另一个单独的二次风集箱相连的二次风出风口离燃烧器喷口更近。
还需要指出的是，在本发明中，外二次风出风口(喷口或者风帽)可以为分散式布置，例如可以是如图所示的类似于点阵的均匀散布，也可以是环绕内二次风布风装置的(多个)环形布置，这些均在本发明的保护范围之内。
在可选的实施例中，可以将二次风集箱布置在炉膛底部，并通过数个向上的管道和布置在炉膛下部的二次风管相通。
在可选的实施例中，邻的贯穿炉膛的二次风管可以共用一个膨胀防护罩。
在可选的实施例中，二次风管22上设置布风孔代替风帽，可以将布风孔沿二次风管截面竖直方向的中心线对称布置在二次风管朝下一侧，这些均在本发明的保护范围之内。
基于以上，本发明提出了一种燃烧器底置的煤粉锅炉，包括：
炉膛；
至少一个燃烧器，设置在炉膛底部，每个燃烧器具有燃烧器喷口，通过所述燃烧器喷口，一次风携带煤粉向上进入所述炉膛；
二次风布风装置，围绕所述燃烧器设置在炉膛底部，用于向上喷射二次风，
其中：
所述二次风布风装置包括内二次风布风装置和外二次风布风装置；
所述内二次风布风装置包括内二次风集箱与内二次风管，所述内二次风管与内二次风集箱相连且设置有位于炉膛内的多个内二次风出风口，所述多个内二次风出风口中的至少一部分内二次风出风口邻近所述燃烧器喷口布置；
所述外二次风布风装置包括外二次风集箱与外二次风管，所述外二次风管与外二次风集箱相连且设置有位于炉膛内的多个外二次风出风口；
所述内二次风集箱独立于外二次风集箱。
相应的，本发明也提出了一种煤粉锅炉的控制方法，包括步骤：
通过设置在炉膛底部的至少一个燃烧器，向炉膛内向上喷射煤粉燃料；和
通过围绕燃烧器设置在炉膛底部的二次风布风装置向炉膛内向上喷射二次风，
其中：
所述二次风布风装置包括内二次风布风装置和外二次风布风装置；所述内二次风布风装置包括内二次风集箱与邻近燃烧器的燃烧器喷口设置的内二次风管，所述外二次风布风装置包括外二次风集箱与外二次风管，所述内二次风集箱独立于外二次风集箱；且
所述方法还包括步骤：分别控制进入到内二次风集箱和外二次风集箱中的风量。
在本发明中，燃料(例如预热燃料)喷入炉膛后，因可与二次风快速、及时掺混，缩短了预热燃料着火时间，强化了预热燃料燃烧稳定性，避免或者减少了预热燃料点火爆燃倾向和燃烧过程发生锅炉振动问题。
在本发明中，通过内二次风和外二次风的有机组合及联合控制，加快预热燃料与内二次风掺混中含氮物质的提前转化，并使炉膛三次风喷口以下主要区域为整体均匀还原性气氛，基本消除局部富氧区域，加大含氮物质的还原程度，降低预热燃料燃烧的NOx排放水平。
本发明中，采用内外二次风分别控制，即二次风分区控制的方式，可以提高锅炉控制的灵活性，有利于强化一次风携带的燃料与二次风的掺混和保证着火和燃烧的稳定，以及有利于控制炉膛内的温度分布和流场分布。
尽管已经示出和描述了本发明的实施例，对于本领域的普通技术人员而言，可以理解在不脱离本发明的原理和精神的情况下可以对这些实施例进行变化、要素组合，本发明的范围由所附权利要求及其等同物限定。

Claims (17)

  1. 一种燃烧器底置的煤粉锅炉，包括：
    炉膛；
    至少一个燃烧器，设置在炉膛底部，每个燃烧器具有燃烧器喷口，通过所述燃烧器喷口，一次风携带煤粉向上进入所述炉膛；
    二次风布风装置，围绕所述燃烧器设置在炉膛底部，用于向上喷射二次风，
    其中：
    所述二次风布风装置包括内二次风布风装置和外二次风布风装置；
    所述内二次风布风装置包括内二次风集箱与内二次风管，所述内二次风管与内二次风集箱相连且设置有位于炉膛内的多个内二次风出风口，所述多个内二次风出风口中的至少一部分内二次风出风口邻近所述燃烧器喷口布置；
    所述外二次风布风装置包括外二次风集箱与外二次风管，所述外二次风管与外二次风集箱相连且设置有位于炉膛内的多个外二次风出风口；
    所述内二次风集箱独立于外二次风集箱。
  2. 根据权利要求1所述的锅炉，其中：
    内二次风管为围绕燃烧器喷口设置的环形管。
  3. 根据权利要求2所述的锅炉，其中：
    所述内二次风集箱在燃烧器喷口下方邻近燃烧器喷口设置或者围绕燃烧器喷口设置。
  4. 根据权利要求2所述的锅炉，其中：
    外二次风管彼此之间平行布置或者在轴向上彼此相对延伸。
  5. 根据权利要求1所述的锅炉，其中：
    所述内二次风管设置有分支管，所述分支管自所述内二次风管延伸，且所述至少一部分内二次风出风口分别设置于所述分支管。
  6. 根据权利要求5所述的锅炉，其中：
    所述内二次风管包括分别设置于燃烧器喷口两侧的两个内二次风管；
    分支管设置在两个内二次风管之间且在内二次风管的延伸方向上位于燃烧器喷口的两侧。
  7. 根据权利要求6所述的锅炉，其中：
    每一个内二次风管设置有两个分支管，两个内二次风管的四个分支管上的内二次风出风口围绕燃烧器喷口设置；或者
    两个分支管连接在两个内二次风管之间，燃烧器喷口位于所述两个分支管之间，且两个分支管上的内二次风出风口围绕燃烧器喷口设置。
  8. 根据权利要求1所述的锅炉，其中：
    所述内二次风管与所述外二次风管彼此平行布置。
  9. 根据权利要求1所述的锅炉，还包括：
    供风控制装置，用于控制内二次风与外二次风的供风比例。
  10. 根据权利要求9所述的锅炉，其中：
    所述供风控制装置对内二次风与外二次风分开控制。
  11. 根据权利要求1-10中任一项所述的锅炉，其中：
    所述内二次风出风口的高度低于燃烧器喷口的高度。
  12. 根据权利要求1-10中任一项所述的锅炉，其中：
    所述内二次风出风口的出风角度朝向燃烧器喷口倾斜。
  13. 根据权利要求1-12中任一项所述的锅炉，其中：
    所述燃烧器为预热燃烧器。
  14. 一种煤粉锅炉的控制方法，包括步骤：
    通过设置在炉膛底部的至少一个燃烧器，向炉膛内向上喷射煤粉燃料；和
    通过围绕燃烧器设置在炉膛底部的二次风布风装置向炉膛内向上喷射二次风，
    其中：
    所述二次风布风装置包括内二次风布风装置和外二次风布风装置；所述内二次风布风装置包括内二次风集箱与邻近燃烧器的燃烧器喷口设置的内二次风管，所述外二次风布风装置包括外二次风集箱与外二次风管，所述内二次风集箱独立于外二次风集箱；且
    所述方法还包括步骤：分别控制进入到内二次风集箱和外二次风集箱 中的风量。
  15. 根据权利要求14所述的方法，还包括步骤：
    控制内二次风的当量比为0.1-0.3；和
    控制外二次风当量比为0.3-0.6，且外二次风与内二次风的二次风总当量比为0.7-0.9。
  16. 根据权利要求14所述的方法，还包括步骤：
    提高内二次风集箱的风量以强化二次风对燃烧器的一次风携带煤粉的掺混。
  17. 根据权利要求14所述的方法，还包括步骤：
    降低内二次风比例且提高外二次风比例，以用于降低炉膛中心温度。
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