WO2023202053A1 - 煤粉深度低氧燃烧系统 - Google Patents

煤粉深度低氧燃烧系统 Download PDF

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WO2023202053A1
WO2023202053A1 PCT/CN2022/132032 CN2022132032W WO2023202053A1 WO 2023202053 A1 WO2023202053 A1 WO 2023202053A1 CN 2022132032 W CN2022132032 W CN 2022132032W WO 2023202053 A1 WO2023202053 A1 WO 2023202053A1
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Prior art keywords
boiler
pulverized coal
mixer
flue gas
combustion
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PCT/CN2022/132032
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English (en)
French (fr)
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张宇博
张良平
王春昌
杨辉
沈植
张海龙
付龙龙
刘超
刘兴
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西安热工研究院有限公司
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Publication of WO2023202053A1 publication Critical patent/WO2023202053A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D1/00—Burners for combustion of 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 
    • F23C7/00—Combustion apparatus characterised by arrangements for air supply
    • 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
    • F23C7/002—Combustion apparatus characterised by arrangements for air supply the air being submitted to a rotary or spinning motion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D1/00—Burners for combustion of pulverulent fuel
    • F23D1/02—Vortex burners, e.g. for cyclone-type combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
    • F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
    • 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
    • F23L15/00—Heating of air supplied for combustion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M5/00—Casings; Linings; Walls
    • F23M5/08—Cooling thereof; Tube walls

Definitions

  • the present disclosure belongs to the technical field of pulverized coal boilers for power stations, and specifically relates to a deep low-oxygen pulverized coal combustion system.
  • the pollutant control of coal-fired boiler generating units in China has reached the international leading level.
  • Most coal-fired thermal generating units have achieved ultra-clean emissions, that is, the nitrogen oxide concentration does not exceed 50 mg/Nm 3 under the condition of a reference oxygen content of 6%.
  • the concentration of sulfur dioxide shall not exceed 35 mg/Nm 3 and the concentration of smoke shall not exceed 5 mg/Nm 3 .
  • the main technologies for nitrogen oxide control include fuel-staged low-nitrogen combustion, air-staged low-nitrogen combustion, and post-combustion denitrification technology (SCR technology).
  • the existing air-staged low-nitrogen combustion completes the combustion process of pulverized coal fuel in stages, which mainly includes two types: (1) deflecting the secondary air jet axis to a certain angle towards the water-cooled wall or controlling the internal and external secondary air to form primary air coal Radial staged combustion with powder air flow inside and secondary air outside. (2) Set up a burnout air nozzle far above the main burner to deliver the combustion air into the furnace in stages during the burnout stage, so that the combustion process proceeds in stages along the furnace flue gas flow direction.
  • most coal-fired boiler units adopt the above two air-staged low-nitrogen combustion technologies.
  • the current common air-staged low-nitrogen combustion does not achieve low oxygen in the primary air, and the primary air rate is relatively high due to the output requirements of the pulverizing system.
  • the nitrogen oxides generated by the initial combustion of pulverized coal cannot be effectively controlled, and the main combustion can only be relied on.
  • the lower secondary air rate and higher burnout air rate in the zone are used to reduce the concentration of nitrogen oxides, which causes a serious oxygen-deficient reducing atmosphere in the main combustion zone and its reduction zone, resulting in serious high-temperature corrosion of the water wall, and also It is easy to cause slagging problems in the furnace.
  • the strong reducing atmosphere in the wall area of the water-cooled wall under low-nitrogen combustion technology is an important reason for severe high-temperature corrosion of the water-cooled wall of current coal-fired boilers.
  • the common shortcomings of this technology are that due to the high combustion air rate, the main combustion zone is overall lack of oxygen, resulting in delayed combustion, upward movement of the flame center, and increased smoke temperature at the furnace outlet, which may cause slagging in the screen superheater, Problems such as overheating of high-temperature heating surfaces.
  • the separated combustion air technology causes insufficient pressure in the burner secondary air box and unsatisfactory aerodynamic field, causing burner burnout to occur from time to time.
  • the cooling air volume of the internal and external secondary air is reduced by more than 20%.
  • the application of separated burnout air technology reduces the differential pressure between the central cooling air and the furnace from more than 400Pa to 0 ⁇ 300Pa, and the corresponding central cooling air volume is reduced by about 1/2. Its cooling effect and destructive effect on the central reflow area Weakened by about 50%. For standby burners under low-load operating conditions, the cooling air volume is significantly insufficient, causing the burner metal to overheat and even burn out.
  • the present disclosure provides a pulverized coal deep low-oxygen combustion system, including a cold air duct, a hot air duct, a boiler flue gas extraction fan, a mixer and a coal grinder; the inlet of the mixer includes a first inlet, a second inlet and a third inlet. three entrances;
  • the inlet of the boiler flue gas extraction fan is connected to the tail flue of the boiler.
  • a boiler main burner is installed on the furnace of the boiler; a pulverized coal burner nozzle is provided in the middle and lower part of the main burner of the boiler, and a secondary air nozzle is provided at the top; the secondary air
  • the nozzle and the combustion air nozzle are connected to the first inlet of the mixer through the hot air duct, the outlet of the boiler flue gas extraction fan is connected to the second inlet of the mixer, the cold air duct is connected to the third inlet of the mixer, and the outlet of the mixer It is connected with the inlet of the coal mill, and the outlet of the coal mill is connected with the nozzle of the pulverized coal burner.
  • the boiler is a tangentially fired boiler or a wall-type opposed fired boiler.
  • the boiler main burner is a once-through burner or a swirl burner.
  • the boiler flue gas extraction fan outlet is connected to the second inlet of the mixer through the boiler flue gas duct.
  • a boiler flue gas regulating valve is provided on the boiler flue gas pipe.
  • a hot air regulating valve is provided on the hot air duct.
  • a cold air regulating valve is provided on the cold air duct.
  • the mixer outlet pipe is provided with a mixed medium regulating valve, a mixed medium pressure measuring device, a mixed medium temperature measuring device and a mixed medium oxygen amount measuring device.
  • Figure 1 is a schematic diagram of the system of the present disclosure.
  • the numbers in the figure are: 1-hot air pipe, 2-hot air regulating valve, 3-cold air pipe, 4-cold air regulating valve, 5-boiler flue gas extraction fan, 6-boiler flue gas pipe, 7-boiler flue gas Regulating valve, 8-mixer, 9-mixed medium regulating valve, 10-mixed medium pressure measuring device, 11-mixed medium temperature measuring device, 12-mixed medium oxygen measuring device, 13-coal grinder, 14-boiler main Burner, 15-pulverized coal burner nozzle, 16-secondary air nozzle, 17-combustion air nozzle.
  • the present invention proposes a pulverized coal depth that can significantly inhibit the initial generation of nitrogen oxides in pulverized coal combustion. Low oxygen combustion system.
  • a pulverized coal deep hypoxic combustion system of the present disclosure includes a hot air pipe 1, a hot air regulating valve 2, a cold air pipe 3, a cold air regulating valve 4, a boiler flue gas extraction fan 5, and a boiler flue gas Pipeline 6, boiler flue gas regulating valve 7, mixer 8, mixed medium regulating valve 9, mixed medium pressure measuring device 10, mixed medium temperature measuring device 11, mixed medium oxygen content measuring device 12, coal grinder 13, boiler main combustion 14, pulverized coal burner nozzle 15, secondary air nozzle 16 and combustion air nozzle 17.
  • a combustion air nozzle 17 is arranged above the main burner 14 of the boiler.
  • the inlet of the boiler flue gas extraction fan 5 is connected to the tail flue of the boiler (such as the steering smoke chamber, the economizer outlet, the air preheater inlet or outlet, etc., which are determined by the pulverizing system).
  • the boiler is a four-corner tangential combustion boiler
  • the boiler main burner 14 is installed at the four corners of the furnace
  • the boiler main burner 14 is a once-through burner or a swirl burner. This disclosure takes the four-corner arrangement of the once-through burner as an example.
  • a pulverized coal burner nozzle 15 is provided in the middle and lower part of the main burner 14 of the boiler, and a secondary air nozzle 16 is provided at the top.
  • the inlet of the mixer 8 includes a first inlet, a second inlet and a third inlet; the secondary air nozzle 16 and the combustion air nozzle 17 are connected to the first inlet of the mixer 8 through the hot air duct 1, and the boiler flue gas extraction fan 5
  • the outlet is connected to the second inlet of the mixer 8 through the boiler flue gas pipe 6, and the flue gas extraction position can be selected at a suitable location behind the tail flue as needed.
  • the cold air pipe 3 is connected to the third inlet of the mixer 8, the outlet of the mixer 8 is connected to the inlet of the coal grinder 13 through the pipe, and the outlet of the coal grinder 13 is connected to the nozzle 15 of the pulverized coal burner.
  • the hot air pipe 1 is provided with a hot air regulating valve 2
  • the cold air pipe 3 is provided with a cold air regulating valve 4
  • the boiler flue gas pipe 6 is provided with a boiler flue gas regulating valve 7.
  • the pipeline between the outlet of the mixer 8 and the inlet of the coal mill 13 is provided with a mixed medium regulating valve 9, a mixed medium pressure measuring device 10, a mixed medium temperature measuring device 11 and a mixed medium oxygen amount measuring device 12.
  • the present disclosure is applicable to pulverized coal boilers using various combustion modes such as once-through burners or swirl burners.
  • This disclosure uses boiler flue gas, hot air, and cold air as the drying and carrying medium for pulverized coal to form a primary air-pulverized mixture that enters the pulverized coal burner to achieve deep low-oxygen and low-nitrogen combustion of pulverized coal and reduce the separation type burnout air. wind rate or cancel the separated burnout wind to eliminate or weaken its influence.
  • the primary air powder formed by the three media of boiler flue gas, hot air, cold air and dry pulverized coal can be flexibly adjusted according to the ignition and combustion characteristics of the pulverized coal to control the lower oxygen content of the primary air powder.
  • incorporating boiler flue gas can greatly reduce the oxygen content of primary air powder, enabling true anoxic combustion in the early stages of pulverized coal combustion, while ensuring that coal While the pulverized ignition is stable, the generation of nitrogen oxides in the early stage of combustion is effectively suppressed, and low-oxygen and low-nitrogen combustion is achieved from the source; due to the cancellation or significant reduction of the wind rate of the separated exhaust air, the pulverized coal in the entire area of the burner
  • the combustion products are mainly oxidizing atmosphere. Reducing the oxygen content of primary air powder can also alleviate the explosion-proof problem of the powder making system.
  • the oxygen content of the primary air powder can be adjusted by adjusting the flow rate of the boiler flue gas mixed in the range of 10% to 18% through the hot air regulating valve 2, the cold air regulating valve 4 and the boiler flue gas regulating valve 7.
  • the disclosed deep low-oxygen pulverized coal combustion system can significantly reduce the primary air rate and separated combustion air rate, increase the secondary air rate, and reduce the flame temperature, thereby simultaneously controlling nitrogen oxides and alleviating high-temperature corrosion of the water wall.
  • the formation of nitrogen oxides from pulverized coal combustion is mainly related to temperature, nitrogen concentration, and oxygen concentration. Due to the lower oxygen content and nitrogen concentration in the primary air, and the addition of flue gas, which can significantly reduce the flame temperature, the generation of nitrogen oxides will be significantly suppressed during the initial ignition and combustion stages of pulverized coal, achieving nitrogen reduction at the source. Oxide control. Post-combustion can appropriately increase the secondary air rate and reduce the burnout air rate, thereby greatly alleviating the reducing atmosphere in the main combustion zone of the furnace and its burnout air area, thereby significantly reducing the risk of high-temperature corrosion of the water wall.
  • the depth of the pulverized coal is low.
  • Oxygen and low-nitrogen combustion realizes initial nitrogen oxide control at the source, so the secondary air rate can be increased and the burnout air rate can be reduced in the later stage, thus greatly alleviating the water-cooled wall in the main combustion area of the furnace and its area with the burnout air
  • the reducing atmosphere on the wall can significantly reduce the risk of high-temperature corrosion of the water-cooled wall.
  • the amount of ammonia sprayed by the SCR system can be significantly reduced, which not only saves the amount of liquid ammonia or urea, but also reduces the air pre-heating caused by ammonia escape.
  • the risk of blockage caused by ammonia hydrogen sulfate deposition in the heater is eliminated, and the explosion-proof problem of the pulverizing system can be solved.
  • this disclosure is based on the original pulverizing system of the pulverized coal boiler. It only needs to add a flue gas extraction flue, a corresponding damper and a boiler flue gas extraction fan to reduce the oxygen concentration of the primary air powder.
  • the system is simple. , and easy to implement.
  • first and second are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as “first” and “second” may explicitly or implicitly include at least one of these features.
  • “plurality” means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.
  • connection In this disclosure, unless otherwise explicitly stated and limited, the terms “installation”, “connection”, “connection”, “fixing” and other terms should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. , or integrated; it can be mechanically connected, electrically connected or communicable with each other; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction between two elements, Unless otherwise expressly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this disclosure can be understood according to specific circumstances.
  • a first feature being “on” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features may be in indirect contact through an intermediary. touch.
  • the terms “above”, “above” and “above” the first feature is above the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature.
  • "Below”, “below” and “beneath” the first feature to the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature has a smaller horizontal height than the second feature.
  • the terms “one embodiment,” “some embodiments,” “example,” “specific examples,” or “some examples” or the like mean that a particular feature, structure, material, or other feature is described in connection with the embodiment or example.
  • Features are included in at least one embodiment or example of the disclosure.
  • the schematic expressions of the above terms are not necessarily directed to the same embodiment or example.
  • the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
  • those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification unless they are inconsistent with each other.

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Abstract

一种煤粉深度低氧燃烧系统，包括锅炉烟气抽取风机(5)和混合器(8)，锅炉主燃烧器(14)上方布置有燃尽风喷口(17)；锅炉烟气抽取风机(5)入口与锅炉的尾部烟道相连，锅炉主燃烧器(14)中下部设置有煤粉燃烧器喷口(15)，顶部设置有二次风喷口(16)；二次风喷口(16)与燃尽风喷口(17)经热空气管道(1)与混合器(8)的第一入口相连，锅炉烟气抽取风机(5)出口与混合器(8)的第二入口相连，冷空气管道(3)与混合器(8)的第三入口相连，混合器(8)的出口与磨煤机(13)入口相连，磨煤机(13)出口与煤粉燃烧器喷口(15)相连。

Description

煤粉深度低氧燃烧系统
相关申请的交叉引用
本申请基于申请号为202210416109.8、申请日为2022年4月20日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本申请作为参考。
技术领域
本公开属于电站煤粉锅炉技术领域，具体涉及一种煤粉深度低氧燃烧系统。
背景技术
目前我国燃煤锅炉发电机组的污染物控制已达到国际领先水平，大部分燃煤火力发电机组已实现超净排放，即在基准氧含量6％条件下氮氧化物浓度不超过50mg/Nm 3、二氧化硫浓度不超过35mg/Nm 3、烟尘浓度不超过5mg/Nm 3。氮氧化物控制的主要技术有燃料分级低氮燃烧、空气分级低氮燃烧、燃烧后脱硝技术(SCR技术)。
现有空气分级低氮燃烧是将煤粉燃料的燃烧过程分阶段完成，主要包括两种：(1)将二次风射流轴线向水冷壁偏转一定角度或控制内外二次风，形成一次风煤粉气流在内、二次风在外的径向分级燃烧。(2)在距主燃烧器上方较远位置处设置燃尽风喷口，将助燃空气在燃尽阶段分级送入炉内，使燃烧过程沿炉膛烟气流向分级分阶段进行。目前大部分燃煤锅炉机组均采用以上两种空气分级低氮燃烧技术。目前常见的空气分级低氮燃烧未实现一次风低氧，且由于制粉系统出力要求引起一次风率偏高，导致煤粉初始燃烧生成的氮氧化物得不到有效控制，只能靠主燃烧区的较低二次风率和较高的燃尽风率来降低氮氧化物浓度，由此引起主燃区及其还原区域内严重的缺氧还原性气氛，导致水冷壁高温腐蚀严重，也易引起炉膛结渣问题。低氮燃烧技术下水冷壁壁面区域强还原性气氛是引起目前燃煤锅炉水冷壁严重高温腐蚀的重要原因。其次该技术的常见缺点还有，由于较高的燃尽风率，主燃区整体缺氧，导致燃烧推迟、火焰中心上移，炉膛出口烟温升高，会引发屏式过热器结渣、高温受热面超温等问题。再者，分离型燃尽风技术引起燃烧器二次风箱压力不足、空气动力场不理想，使燃烧器烧损现象时有发生。如对于旋流燃烧器锅炉，在燃烧器风箱进口风门开度相同时，采用燃尽风技术后，内外二次风的冷却风量减少达20％以上。分离型燃尽风技术的应用，使得中心冷却风与炉膛差压由400Pa以上减小至0～300Pa，对应的中心冷却风量减少1/2左右，其冷却作用及其对中心回流区的破坏作用减弱约50％。对于低负荷运行工况下的备用燃烧器，其冷却风量显著不足，导致燃烧器金属超温、甚至烧损。
常见的SCR技术应用后，由于喷氨引起的氨逃逸及增加的三氧化硫转化，在回转式空气预热器和低温省煤器等锅炉排烟余热回收利用装置中产生硫酸氢氨沉积、堵塞和腐蚀，轻则增大锅炉烟道阻力、引风机耗电升高，严重时甚至导致引风机失速，机组非停。
现有空气分级低氮燃烧技术及SCR技术的应用，导致燃煤电站煤粉锅炉普遍出现严重 的水冷壁高温腐蚀和空气预热器和低温省煤器堵塞问题，严重影响锅炉机组的运行安全。
只有采取措施控制煤粉燃烧初期的氮氧化物生成量，才能从根本上解决燃尽风过度使用和SCR系统喷氨量带来的负面影响。
发明内容
本公开提供了一种煤粉深度低氧燃烧系统，包括冷空气管道、热空气管道、锅炉烟气抽取风机、混合器以及磨煤机；混合器的入口包括第一入口、第二入口和第三入口；
锅炉主燃烧器上方布置有燃尽风喷口；
锅炉烟气抽取风机入口与锅炉的尾部烟道相连，锅炉的炉膛上安装有锅炉主燃烧器；锅炉主燃烧器中下部设置有煤粉燃烧器喷口，顶部设置有二次风喷口；二次风喷口与燃尽风喷口经热空气管道与混合器的第一入口相连，锅炉烟气抽取风机出口与混合器的第二入口相连，冷空气管道与混合器的第三入口相连，混合器的出口与磨煤机入口相连，磨煤机出口与煤粉燃烧器喷口相连。
在一些实施例中，锅炉为四角切圆燃烧锅炉或墙式对冲燃烧锅炉。
在一些实施例中，锅炉主燃烧器为直流燃烧器或旋流燃烧器。
在一些实施例中，锅炉烟气抽取风机出口经锅炉烟气管道与混合器的第二入口相连。
在一些实施例中，锅炉烟气管道上设置有锅炉烟气调节阀。
在一些实施例中，热空气管道上设置有热空气调节阀。
在一些实施例中，冷空气管道上设置有冷空气调节阀。
在一些实施例中，混合器出口管道上设置有混合介质调节阀、混合介质压力测量装置、混合介质温度测量装置和混合介质氧量测量装置。
附图说明
图1为本公开的系统示意图。
图中标号，1-热空气管道、2-热空气调节阀、3-冷空气管道、4-冷空气调节阀、5-锅炉烟气抽取风机、6-锅炉烟气管道、7-锅炉烟气调节阀、8-混合器、9-混合介质调节阀、10-混合介质压力测量装置、11-混合介质温度测量装置、12-混合介质氧量测量装置、13-磨煤机、14-锅炉主燃烧器、15-煤粉燃烧器喷口、16-二次风喷口、17-燃尽风喷口。
具体实施方式
以下结合附图对本公开作进一步的详细说明。
针对目前电站煤粉锅炉燃尽风率高、水冷壁高温腐蚀、SCR喷氨量大、空预器堵塞等问题，本发明提出一种可明显抑制煤粉燃烧初始氮氧化物生成的煤粉深度低氧燃烧系统。
参见图1，本公开的一种煤粉深度低氧燃烧系统，包括热空气管道1、热空气调节阀2、冷空气管道3、冷空气调节阀4、锅炉烟气抽取风机5、锅炉烟气管道6、锅炉烟气调节阀7、混合器8、混合介质调节阀9、混合介质压力测量装置10、混合介质温度测量装置11、混合 介质氧量测量装置12、磨煤机13、锅炉主燃烧器14、煤粉燃烧器喷口15、二次风喷口16以及燃尽风喷口17。
锅炉主燃烧器14上方布置有燃尽风喷口17。
锅炉烟气抽取风机5入口与锅炉的尾部烟道(如转向烟室、省煤器出口、空气预热器入口或出口等部位，具体由制粉系统确定)相连，锅炉为四角切圆燃烧锅炉，炉膛四角安装有锅炉主燃烧器14，锅炉主燃烧器14为直流燃烧器或旋流燃烧器。本公开以直流燃烧器四角布置为例说明。
锅炉主燃烧器14中下部设置有煤粉燃烧器喷口15，顶部设置有二次风喷口16。
混合器8的入口包括第一入口、第二入口和第三入口；二次风喷口16与燃尽风喷口17经热空气管道1与混合器8的第一入口相连，锅炉烟气抽取风机5出口经锅炉烟气管道6与混合器8的第二入口相连，烟气抽取位置可根据需要在尾部烟道后合适部位选择。冷空气管道3与混合器8的第三入口相连，混合器8的出口经管道与磨煤机13入口相连，磨煤机13出口与煤粉燃烧器喷口15相连。
其中，热空气管道1上设置有热空气调节阀2，冷空气管道3上设置有冷空气调节阀4，锅炉烟气管道6上设置有锅炉烟气调节阀7。
混合器8的出口与磨煤机13入口之间的管道上设置有混合介质调节阀9、混合介质压力测量装置10、混合介质温度测量装置11和混合介质氧量测量装置12。
本公开适用于采用直流燃烧器或旋流燃烧器等各种燃烧方式的煤粉锅炉。
本公开采用锅炉烟气、热空气、冷空气共同作为煤粉干燥和携带介质，组成一次风粉混合物进入煤粉燃烧器，实现煤粉深度低氧、低氮燃烧，减小分离型燃尽风的风率或取消分离型燃尽风，以消除或减弱其影响。
锅炉烟气、热空气、冷空气三介质与干燥煤粉形成的一次风粉，可根据煤粉着火和燃烧特性灵活调整其比例，控制较低的一次风粉含氧量。与现有常见煤粉锅炉燃烧系统、空气分级低氮燃烧技术相比，掺入锅炉烟气可大大降低一次风粉含氧量，使煤粉燃烧初期实现真正意义的缺氧燃烧，在保证煤粉着火稳定的同时，有效抑制燃烧初期氮氧化物生成，从源头上实现低氧、低氮燃烧；由于取消或大幅减小了分离型燃尽风的风率，在燃烧器整个区域，煤粉燃烧产物以氧化性气氛为主。一次风粉含氧量降低还可同时缓解制粉系统的防爆问题。
一次风粉含氧量可通过热空气调节阀2、冷空气调节阀4和锅炉烟气调节阀7调整掺入锅炉烟气的流量在10％～18％范围内来调节。
本公开的煤粉深度低氧燃烧系统可显著降低一次风率和分离型燃尽风率、提高二次风率、降低火焰温度，达到同时控制氮氧化物、缓解水冷壁高温腐蚀的目的。
本公开的工作原理如下：
通过在一次风中掺入锅炉烟气降低一次风氧量实现煤粉深度低氧燃烧，达到控制煤粉燃烧初始氮氧化物浓度的目的。从锅炉尾部烟道合适部位抽取烟气，与现有热空气、冷空气混合后进入制粉系统，携带干燥煤粉作为一次风送入锅炉主燃烧器，从而在煤粉主燃烧器中形成深度低氧介质，由于煤粉气流初期燃烧阶段主要是一次风粉的着火燃烧，从而实现了煤粉 初始深度低氧燃烧。煤粉燃烧氮氧化物生成主要与温度、氮浓度、氧浓度有关。由于一次风中较低的含氧量和氮气浓度，加上烟气掺入可显著降低火焰温度，故在煤粉初始着火、燃烧阶段氮氧化物生成会显著受到抑制，在源头上实现了氮氧化物控制。后期燃烧可适当提高二次风率、降低燃尽风率，由此大大缓解炉膛主燃烧区及其与燃尽风区域的还原性气氛，从而显著降低水冷壁高温腐蚀风险。
本公开中通过设置锅炉烟气抽取风机、冷空气管道和热空气管道，通过抽取锅炉烟气，与热空气、冷空气混合介质干燥、携带煤粉直接进入煤粉燃烧器，实现煤粉深度低氧、低氮燃烧，在源头上实现了初始氮氧化物控制，所以后期可提高二次风率、降低燃尽风率，由此大大缓解炉膛主燃烧区及其与燃尽风区域的水冷壁壁面还原性气氛，从而显著降低水冷壁高温腐蚀风险；同时初始氮氧化物排放得到有效控制后，SCR系统喷氨量可大幅下降，不仅节省液氨或尿素用量，还能降低氨逃逸引起空气预热器硫酸氢氨沉积堵塞风险，并且可解决制粉系统的防爆问题。
进一步的，本公开是在煤粉锅炉原有制粉系统基础上，仅需增加烟气抽取烟道、相应的调节风门与锅炉烟气抽取风机等，以降低一次风粉的氧浓度，系统简单，且容易实施。
在本公开的描述中，需要理解的是，术语“中心”、“纵向”、“横向”、“长度”、“宽度”、“厚度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”“内”、“外”、“顺时针”、“逆时针”、“轴向”、“径向”、“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本公开和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本公开的限制。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本公开的描述中，“多个”的含义是至少两个，例如两个，三个等，除非另有明确具体的限定。
在本公开中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；可以是机械连接，也可以是电连接或彼此可通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系，除非另有明确的限定。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本公开中的具体含义。
在本公开中，除非另有明确的规定和限定，第一特征在第二特征“上”或“下”可以是第一和第二特征直接接触，或第一和第二特征通过中间媒介间接接触。而且，第一特征在第二特征“之上”、“上方”和“上面”可是第一特征在第二特征正上方或斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”可以是第一特征在第二特征正下方或斜下方，或仅仅表示第一特征水平高度小于第二特征。
在本公开中，术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本公开的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施 例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
尽管已经示出和描述了上述实施例，可以理解的是，上述实施例是示例性的，不能理解为对本公开的限制，本领域普通技术人员对上述实施例进行的变化、修改、替换和变型均在本公开的保护范围内。

Claims (8)

  1. 一种煤粉深度低氧燃烧系统，包括冷空气管道(3)、热空气管道(1)、锅炉烟气抽取风机(5)、混合器(8)以及磨煤机(13)；混合器(8)的入口包括第一入口、第二入口和第三入口；
    锅炉主燃烧器(14)上方布置有燃尽风喷口(17)；
    锅炉烟气抽取风机(5)入口与锅炉的尾部烟道相连，锅炉的炉膛上安装有锅炉主燃烧器(14)；锅炉主燃烧器(14)中下部设置有煤粉燃烧器喷口(15)，顶部设置有二次风喷口(16)；二次风喷口(16)与燃尽风喷口(17)经热空气管道(1)与混合器(8)的第一入口相连，锅炉烟气抽取风机(5)出口与混合器(8)的第二入口相连，冷空气管道(3)与混合器(8)的第三入口相连，混合器(8)的出口与磨煤机(13)入口相连，磨煤机(13)出口与煤粉燃烧器喷口(15)相连。
  2. 根据权利要求1所述的煤粉深度低氧燃烧系统，其中，锅炉为四角切圆燃烧锅炉或墙式对冲燃烧锅炉。
  3. 根据权利要求1或2所述的煤粉深度低氧燃烧系统，其中，锅炉主燃烧器(14)为直流燃烧器或旋流燃烧器。
  4. 根据权利要求1至3中任一项所述的煤粉深度低氧燃烧系统，其中，锅炉烟气抽取风机(5)出口经锅炉烟气管道(6)与混合器(8)的第二入口相连。
  5. 根据权利要求4所述的煤粉深度低氧燃烧系统，其中，锅炉烟气管道(6)上设置有锅炉烟气调节阀(7)。
  6. 根据权利要求1至5中任一项所述的煤粉深度低氧燃烧系统，其中，热空气管道(1)上设置有热空气调节阀(2)。
  7. 根据权利要求1至6中任一项所述的煤粉深度低氧燃烧系统，其中，冷空气管道(3)上设置有冷空气调节阀(4)。
  8. 根据权利要求1至7中任一项所述的煤粉深度低氧燃烧系统，其中，混合器(8)出口管道上设置有混合介质调节阀(9)、混合介质压力测量装置(10)、混合介质温度测量装置(11)和混合介质氧量测量装置(12)。
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