Coal and ammonia / methane coupled reburning low nitrogen combustion device, method and system

Abstract

The present invention discloses a low-nitrogen combustion device, method and system for coupling reburning of coal and ammonia / methane. The low-nitrogen combustion device comprises a boiler, wherein the combustion chamber of the boiler is divided into a main combustion zone, a reburning zone, a burnout zone and a NOx zone along the direction of flue gas flow. x The boiler side wall is embedded with the main combustion burner at the position corresponding to the main combustion zone, the reburning burner at the position corresponding to the reburning zone, the burnout air nozzle at the position corresponding to the burnout zone, and the NO x The reduction zone is embedded with an ammonia injection device; the main combustion burner is used to pass coal powder and air for combustion, and the reburning burner is used to pass CH4 and NH3 for combustion. Among them, the main combustion zone fuel is coal powder, and the reburning zone fuel is a mixture of CH4 and NH3. The ammonia injection device is used to inject NO x The reduction zone sprays a mixture of ammonia and air as a reducing agent to reduce NO x NO in the reduction zone x The fuel in the main combustion zone accounts for 70-85wt% of the total fuel, which can improve the fuel combustion efficiency and reduce the NO in the tail gas. x concentration.

Description

Technical Field

[0001] The present invention belongs to the technical field of boilers, and in particular relates to a coal and ammonia / methane coupled reburning low-nitrogen combustion device, method and system. Background Art

[0002] In recent years, ammonia has received more and more attention as a zero-carbon fuel, but pure ammonia, coal, methane and ammonia coupled combustion is one of the research hotspots. Although the mixed combustion of the three can reduce carbon emissions, pure ammonia is difficult to ignite. Fuels such as coal and methane can promote the ignition of ammonia and promote its full combustion, but ammonia is a fuel rich in nitrogen, which easily produces a large amount of nitrogen oxides during the combustion process. Therefore, how to ensure that less nitrogen oxides are generated during the coupled combustion of coal, methane and ammonia is one of the research focuses. In view of the shortcomings of the coupled combustion of coal, methane and ammonia, a method of coupling reburning of coal and NH3 / CH4 to control low NO x There is an urgent need for devices, methods and systems for (nitrogen oxides) generation. Summary of the Invention

[0003] In order to solve the above technical problems, one of the purposes of the present invention is to provide a method for controlling NO in the coupled combustion process of coal, CH4 and NH3. x The generation of NO generated during the combustion process x A low nitrogen combustion unit with coal and ammonia / methane coupled reburning with optimized content.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a coal and ammonia / methane coupled reburning low nitrogen combustion device, comprising a boiler with an exhaust gas discharge port, wherein the combustion chamber of the boiler is divided into a main combustion zone, a reburning zone, a burnout zone and a NO x reduction zone;

[0005] The side wall of the boiler is embedded with a main combustion burner at a position corresponding to the main combustion zone, the side wall of the boiler is embedded with a reburning burner at a position corresponding to the reburning zone, the side wall of the boiler is embedded with a burnout air nozzle at a position corresponding to the burnout zone, and the side wall of the boiler is embedded with a NO x An ammonia spraying device is embedded in the reduction zone;

[0006] The main combustion burner is used to introduce pulverized coal and air and burn in the main combustion zone; the reburning burner is used to introduce a mixed gas of NH3 and CH4 as fuel and burn in the reburning zone, wherein the main combustion zone fuel is pulverized coal, and the reburning zone fuel is a mixed gas of CH4 and NH3; the ammonia injection device is used to inject NO x The reduction zone sprays a mixture of ammonia and air to remove the NO x NO in the reduction zone x Perform reduction processing;

[0007] The main combustion zone fuel accounts for 70-85 wt% of the total fuel, wherein the total fuel is the sum of the main combustion zone fuel and the reburning zone fuel;

[0008] The ratio of CH4 to NH3 in the reburning zone fuel is β, where

[0009] Among them, C CH4 represents the mass fraction of methane in the fuel in the reburning zone, C NH3 Represents the mass fraction of ammonia in the fuel in the reburning zone.

[0010] In the above technical solution, the excess air coefficient of the main combustion zone is 1.1-1.5; the excess air coefficient of the reburning zone is 0.75-0.85; and the excess air coefficient of the burnout zone is 1.1-1.3.

[0011] The ammonia content in the mixed gas sprayed by the ammonia spraying device in the above technical solution is 3-8% by volume.

[0012] In the above technical solution, the β value is 0.5-1.

[0013] The combustion temperature of the reburning zone in the above technical solution is 1200-1400℃; the NO x The reduction zone is located above the burnout zone at a temperature of 850-1100°C.

[0014] In addition, the present invention also provides a method for optimizing the ratio of coal, CH4 and NH3 in the fuel to ensure that the combustion efficiency in the boiler remains at a high level, so that the initial NO at the exhaust outlet is reduced. x The content is at a low level, thereby reducing NO x Treatment costs in the reduction area.

[0015] In order to achieve the above object, the technical solution of the present invention is as follows: A combustion method corresponding to the above combustion device comprises the following steps:

[0016] Step 1: When pulverized coal and NH3 / CH4 are injected into the boiler through the main combustion burner and the afterburning burner for combustion, overburn air is injected through the overburn air nozzle;

[0017] Step 2: Real-time monitoring of NO at the exhaust outlet x Concentration, when NO x Concentration below 150 mg / m 3 or higher than 200 mg / m 3 When the NO content of the tail gas outlet is adjusted, the ratio of the reburning zone fuel to the total fuel amount and / or the β value of the reburning zone fuel is adjusted. xConcentration higher than 150 mg / m 3 , but less than 200mg / m 3 ;

[0018] Step 3: Ammonia injection device to NO x The reduction zone sprays a mixture of ammonia and air, and adjusts the injection amount of the mixed gas to make the NO x Concentration less than 50 mg / m 3 .

[0019] In the above technical solution, in step 2, when the NO x Concentration higher than 200 mg / m 3 When the NO content of the exhaust port is adjusted, the ratio of the reburning zone fuel to the total fuel amount is increased and / or the β value of the reburning zone fuel is reduced. x Concentration less than 200 mg / m 3 , but higher than 150mg / m 3 ; When the NO x Concentration below 150 mg / m 3 When the NO content of the exhaust port is adjusted, the ratio of the reburning zone fuel to the total fuel amount is reduced and / or the β value of the reburning zone fuel is increased. x Concentration higher than 150 mg / m 3 , but less than 200mg / m 3 .

[0020] In the above technical solution, when the NO x Concentration higher than 200 mg / m 3 The specific steps of step 2 are as follows: first increase the proportion of reburning zone fuel to the total fuel by 1wt%, if the NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the amount of fuel in the reburning zone is increased by 1 wt%, the NO x The concentration is continuously below 200 mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the proportion of the reburning zone fuel to the total fuel cannot be adjusted to reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 When the β value of the fuel in the reburning zone is lower than 1%, if the exhaust gas outlet is NO x Concentration decreased by 10 mg / m3 Above, but still higher than 200mg / m 3 When the β value of the fuel in the reburning zone is reduced by 1%, the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 If the following is true, proceed directly to step 3.

[0021] In the above technical solution, when the NO x Concentration below 150 mg / m 3 The specific steps of step 2 are as follows: first reduce the proportion of reburning zone fuel to the total fuel by 1wt%, if the NO x Concentration increased by 10 mg / m 3 Above, but still below 150mg / m 3 When the amount of fuel in the reburning zone is less than 1wt%, the proportion of fuel in the reburning zone to the total fuel will continue to decrease by 1wt% until the NO x Concentrations consistently above 150 mg / m 3 , but less than 200mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the proportion of the reburning zone fuel to the total fuel cannot be adjusted to reduce the NO x Concentration increased by 10 mg / m 3 Above or cannot be NO x Concentration increased to 150 mg / m 3 If the β value of the fuel in the reburning zone is increased by 1%, if the NO x Concentration increased by 10 mg / m 3 Above, but still below 150mg / m 3 When the β value of the fuel in the reburning zone is increased by 1%, the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration increased by 10 mg / m 3 Above or cannot be NO x Concentration increased to 150 mg / m 3 If the following is true, proceed directly to step 3.

[0022] The present invention also provides a combustion system, comprising a real-time monitoring device, an online analysis module, an optimization guidance module and the combustion device as described above, wherein the real-time monitoring device is used to monitor the NO x concentration, the online analysis module is used to analyze and judge the monitoring results of the real-time monitoring device, and the optimization guidance module is used to give instructions for adjusting the proportion of the reburning zone fuel to the total fuel amount, adjusting the β value, or directly injecting ammonia from the ammonia injection device according to the analysis results of the online analysis module.

[0023] The beneficial effect of the present invention is that the present invention can be used to monitor the real-time NO x The concentration provides optimization guidance for fuel distribution in the main combustion zone and reburning zone, based on the historical operation data of the boiler and NO x Real-time emission concentration to determine target NO x Concentration is 150-200 mg / m 3 By adjusting the fuel ratio of the boiler (adjusting the proportion of the reburning zone fuel to the total fuel amount and the β value), the NO x The concentration reaches 150-200 mg / m 3 When the ammonia spraying device is used to spray a mixture of ammonia and air to the NO x NO in the reduction zone x In addition, the fuel in the boiler can be fully burned to ensure high combustion efficiency, while the NO x Lower concentration, reducing NO x Reduction treatment costs; adding NH3 during the combustion process can achieve low-carbon combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a simplified structural diagram of a coal and ammonia / methane coupled reburning low-nitrogen combustion device according to an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the structure of a single angle furnace in an embodiment of the present invention;

[0026] Figure 3 Schematic diagram of the connection between the real-time monitoring device, the online analysis module and the optimization guidance module in an embodiment of the present invention.

[0027] In the figure: 1 boiler, 11 main combustion zone, 12 reburning zone, 13 burnout zone, 14 NO xReduction zone, 15 main combustion burner, 16 afterburning burner, 17 burnout air nozzle, 18 ammonia injection device, 19 tail gas discharge port, 2 coal feeding system, 3 methane supply system, 31 first valve, 4 ammonia supply system, 41 second valve, 42 third valve, 5 first mixing device, 6 second mixing device, 7 primary air fan, 8 fan, 9 real-time monitoring device. DETAILED DESCRIPTION

[0028] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0029] like Figure 1 As shown, the present invention provides a coal and ammonia / methane coupled reburning low nitrogen combustion device, comprising a boiler 1 with an exhaust gas discharge port 19, wherein the combustion chamber of the boiler 1 is divided into a main combustion zone 11, a reburning zone 12, a burnout zone 13 and a NO x reduction zone 14;

[0030] A main combustion burner 15 is embedded on the side wall of the boiler at a position corresponding to the main combustion zone, a reburning burner 16 is embedded on the side wall of the boiler at a position corresponding to the reburning zone, and an overburning air nozzle 17 is embedded on the side wall of the boiler at a position corresponding to the burnout zone (the overburning air nozzle injects overburning air into the boiler to ensure that the pulverized coal, CH4 and NH3 fed from the main combustion zone and the reburning zone are fully burned). x An ammonia injection device 18 is embedded in the reduction zone;

[0031] The main combustion burner is used to introduce pulverized coal and air (provided by the primary air blower 7) and burn in the main combustion zone (the pulverized coal is carried by the primary air through the main combustion burner into the boiler, so that the pulverized coal is fully burned). The reburning burner is used to introduce a mixed gas of CH4 and NH3 as fuel and burn in the reburning zone, so that the reburning zone is in a reducing atmosphere, so that the mixed gas of NH3 and CH4 participates in the combustion reaction while reducing part of the NO generated during the combustion process. x The ammonia injection device is used to inject the NO x The reduction zone sprays a mixture of ammonia and air (provided by fan 8) as a reducing agent to reduce the NO x NO in the reduction zone x Perform reduction treatment (to reduce NO at the exhaust outlet) x content);

[0032] The fuel in the main combustion zone is pulverized coal, and the fuel in the reburning zone is a mixture of CH4 and NH3;

[0033] The main combustion zone fuel accounts for 70-85 wt% of the total fuel, wherein the total fuel is the sum of the main combustion zone fuel and the reburning zone fuel;

[0034] The ratio of CH4 to NH3 in the reburning zone fuel is β, where

[0035] Among them, C CH4 represents the mass fraction of methane in the fuel in the reburning zone, C NH3 Represents the mass fraction of ammonia in the fuel in the reburning zone.

[0036] The excess air coefficient of the main combustion zone in the above technical solution is 1.1-1.5 (which can make the coal powder burn fully and generate a large amount of NO during the combustion process). x ).

[0037] The excess air coefficient of the reburning zone in the above technical solution is 0.75-0.85 (so that a reducing atmosphere is formed in the reburning zone inside the boiler to ensure that NH3 and CH4 are burned while reducing part of the NO generated in the main combustion zone). x ).

[0038] The excess air coefficient of the burnout zone in the above technical solution is 1.1-1.3 (to ensure complete combustion).

[0039] The ammonia content in the mixed gas sprayed by the ammonia spraying device in the above technical solution is 3-8% by volume.

[0040] In the above technical solution, the β value is 0.5-1.

[0041] The combustion temperature of the reburning zone in the above technical solution is 1200-1400℃, and the excess air coefficient is preferably 0.75-0.85, so as to ensure that the reburning zone is in a high-temperature reducing atmosphere. CH4 and NH3 in this zone can participate in the combustion reaction as fuel and can also act as reducing agents to reduce part of the NO generated in the main combustion zone. x Reduction, reduction of NO x Net production during combustion.

[0042] The NO x The reduction zone is located above the burnout zone at a temperature of 850-1100°C.

[0043] The present invention also provides a combustion method for the above combustion device, comprising the following steps:

[0044] Step 1: When the main burner and the afterburner burner on the boiler are burning, overburn air is injected through the overburn air nozzle;

[0045] Step 2: Use real-time monitoring device 9 (flue gas analyzer) to monitor the NO in the tail gas outlet in real time. x Concentration, when NO x Concentration below 150 mg / m 3 or higher than 200 mg / m 3 When the NO content of the tail gas outlet is adjusted, the ratio of the reburning zone fuel to the total fuel amount and / or the β value of the reburning zone fuel is adjusted. x Concentration higher than 150 mg / m 3 , but less than 200mg / m 3 ;

[0046] Step 3: Ammonia injection device to NO x The reduction zone sprays a mixture of ammonia and air, and adjusts the injection amount of the mixed gas to make the NO x Concentration less than 50 mg / m 3 .

[0047] In the above technical solution, in step 2, when the NO x Concentration higher than 200 mg / m 3 When the NO content of the exhaust port is adjusted, the ratio of the reburning zone fuel to the total fuel amount is increased and / or the β value of the reburning zone fuel is reduced. x Concentration less than 200 mg / m 3 , but higher than 150mg / m 3 ; When the NO x Concentration below 150 mg / m 3 When the NO content of the exhaust port is adjusted, the ratio of the reburning zone fuel to the total fuel amount is reduced and / or the β value of the reburning zone fuel is increased. x Concentration higher than 150 mg / m 3 , but less than 200mg / m 3 .

[0048] In the above technical solution, when the NO x Concentration higher than 200 mg / m 3 The specific steps of step 2 are as follows: first increase the proportion of reburning zone fuel to the total fuel by 1wt%, if the NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the amount of fuel in the reburning zone is increased by 1 wt%, the NOx The concentration is continuously below 200 mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the proportion of the reburning zone fuel to the total fuel cannot be adjusted to reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 When the β value of the fuel in the reburning zone is lower than 1%, if the exhaust gas outlet is NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the β value of the fuel in the reburning zone is reduced by 1%, the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 If the following is true, proceed directly to step 3.

[0049] When the NO x Concentration below 150 mg / m 3 The specific steps of step 2 are as follows: first reduce the proportion of reburning zone fuel to the total fuel by 1wt%, if the NO x Concentration increased by 10 mg / m 3 Above, but still below 150mg / m 3 When the amount of fuel in the reburning zone is less than 1wt%, the proportion of fuel in the reburning zone to the total fuel will continue to decrease by 1wt% until the NO x Concentrations consistently above 150 mg / m 3 , but less than 200mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the proportion of the reburning zone fuel to the total fuel cannot be adjusted to reduce the NO x Concentration increased by 10 mg / m 3 Above or cannot be NO x Concentration increased to 150 mg / m 3 If the β value of the fuel in the reburning zone is increased by 1%, if the NO x Concentration increased by 10 mg / m 3 Above, but still below 150mg / m 3When the β value of the fuel in the reburning zone is increased by 1%, the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration increased by 10 mg / m 3 Above or cannot be NO x Concentration increased to 150 mg / m 3 If the following is true, proceed directly to step 3.

[0050] like Figure 3 As shown, the present invention also provides a combustion system, including a real-time monitoring device 9, an online analysis module, an optimization guidance module and the combustion device as described above, wherein the real-time monitoring device 9 is used to monitor the NO x The online analysis module is used to analyze and judge the monitoring results of the real-time monitoring device 9, and the optimization guidance module is used to give instructions for adjusting the proportion of the reburning zone fuel to the total fuel amount, adjusting the β value, or directly injecting ammonia from the ammonia injection device according to the analysis results of the online analysis module. The online analysis module and the optimization guidance module (both of which are programs in the computer) work together to complete the logical judgment and instruction sending in the following method (based on the NO at the exhaust outlet) x Concentration higher than 200 mg / m 3 For example):

[0051] When the real-time monitoring device 9 monitors the NO x Concentration higher than 200 mg / m 3 When the online analysis module obtains and analyzes the data, the optimization guidance module issues an instruction to increase the proportion of reburning zone fuel to the total fuel by 1wt%. After the instruction is completed, if the real-time monitoring device 9 detects NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the online analysis module obtains and analyzes the data, the optimization guidance module issues an instruction to continue increasing the proportion of the reburning zone fuel to the total fuel by 1wt%. This process is repeated until the real-time monitoring device 9 detects NO at the exhaust outlet. x The concentration is continuously below 200 mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, the online analysis module will obtain and analyze the data, and the optimization guidance module will issue a prompt that the adjustment is completed; if the adjustment of the proportion of the reburning zone fuel to the total fuel volume cannot reduce the NO xConcentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 When the value of β in the fuel of the reburning zone is less than 1%, the optimization guidance module will issue an instruction to reduce the β value of the fuel in the reburning zone by 1%. After the instruction is completed, if the real-time monitoring device 9 detects NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the online analysis module obtains and analyzes the data, the optimization guidance module issues an instruction to continue reducing the β value of the fuel in the reburning zone by 1%. This process is repeated until the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 After more than 60 seconds, the optimization guidance module will issue a prompt that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 When the following is true, the optimization guidance module issues an instruction to directly proceed to step 3 (wherein, the optimization guidance module also has an information feedback function. After the instruction is issued, the operator can feedback the instruction completion information to the optimization guidance module after completing the corresponding instruction).

[0052] The system can conveniently realize human-computer interaction, that is, the real-time monitoring device 9 processes the real-time detection data and informs the operator of the generated operation instructions to perform corresponding operations, thereby improving its automation.

[0053] Example 1

[0054] See Figure 2 As shown, this embodiment proposes a coal and ammonia / methane coupled reburning low-nitrogen combustion device, which specifically includes: a single-angle furnace (i.e., boiler 1), a coal feeding system 2, a methane supply system 3, an ammonia supply system 4, a first mixing device 5, a second mixing device 6, a main combustion burner 15, a reburning burner 16, a burnout air nozzle 17, and an ammonia injection device 18.

[0055] In this embodiment, the single angle furnace is 5m high, of which the main combustion zone, reburning zone and burnout zone are all 1.5m high, and the NO x The reduction zone is 0.5m.

[0056] The main combustion burner is arranged at a position corresponding to the main combustion zone on the side wall of the single-angle furnace, and is used to introduce primary air and pulverized coal supplied by the coal feeding system.

[0057] The reburner is installed on the side wall of the single-angle furnace at a location corresponding to the reburning zone. The two inlets of the first mixing device are connected to the methane supply system and the ammonia supply system, respectively. The outlet of the first mixing device is connected to the reburner, and is used to mix methane and ammonia before feeding them to the reburner. A first valve 31 is provided at the outlet of the methane supply system, a second valve 41 is provided at the connection between the ammonia supply system and the second mixing device, and a third valve 42 is provided at the connection between the ammonia supply system and the first mixing device.

[0058] One inlet of the second mixer is connected to the ammonia supply system, and the other inlet is connected to the air outlet of the fan 8 (pumping out air). The outlet of the second mixer is connected to the ammonia injection device. The second mixer is used to mix ammonia and air and then send them to the ammonia injection device.

[0059] Coal powder equivalent to 80wt% of the total fuel amount is carried by the primary air into the single-angle furnace from the left side of the single-angle furnace (x=0m, x is the coordinate of the flue gas flow direction of the single-angle furnace). At the same time, the amount of primary air carrying the coal powder is adjusted to ensure that the excess air coefficient in this area is 1.2, so that the coal powder can be fully burned in the main combustion area of ​​the single-angle furnace.

[0060] At x=1.5m, CH4 and NH3 equivalent to 20wt% of the total fuel are fed into the single-angle furnace through the reburning burner, wherein CH4 accounts for 70wt% of the fuel in the reburning zone and NH3 accounts for 30wt% of the fuel in the reburning zone, ensuring that the temperature range of this zone is about 1200-1400℃ and the excess air coefficient is 0.8, thereby ensuring that the reburning zone is in a high-temperature reducing atmosphere. CH4 and NH3 in this zone not only participate in the combustion reaction as fuel, but also act as reducing agents to reduce part of the NO generated in the main combustion zone. x Reduction, thereby reducing NO x Net production during combustion.

[0061] At x=3m, after the burnout air is sent in through the burnout air nozzle, the excess air coefficient in the burnout zone is guaranteed to be 1.2, ensuring complete combustion of the fuel and improving combustion efficiency.

[0062] Novaplus MRU multifunctional flue gas analyzer (real-time monitoring device 9) was used to measure the flue gas at x = 4.5m online to obtain NO x After the concentration is reached, the ammonia-nitrogen molar ratio is 1.5 (the amount of ammonia injected is proportional to the amount of NO in the flue gas). x The area is sprayed with ammonia gas diluted with air to a volume concentration of 5%, and the temperature of the area is kept between 850-1100 ° C to remove the remaining NO x Fully reduce the NO xIt was found that the above method made NO x Emission concentration is less than 50mg / m 3 , in line with national emission standards.

[0063] It should be noted that the above detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0064] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0065] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the present application described herein can, for example, be implemented in an order other than that illustrated or described herein.

[0066] Also, when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementations.

[0067] In addition, the terms "comprises" and "having" and any variations thereof are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0068] For ease of description, spatially relative terms, such as "on," "above," "on the upper surface of," and "upper," may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0069] For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above" can encompass both an orientation of "above" and "below." The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0070] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A coal and ammonia / methane coupled reburning low nitrogen combustion device, characterized in that: The boiler comprises a tail gas discharge port, wherein the combustion chamber of the boiler is divided into a main combustion zone, a reburning zone, a burnout zone and a NO x reduction zone; The side wall of the boiler is embedded with a main combustion burner at a position corresponding to the main combustion zone, the side wall of the boiler is embedded with a reburning burner at a position corresponding to the reburning zone, the side wall of the boiler is embedded with a burnout air nozzle at a position corresponding to the burnout zone, and the side wall of the boiler is embedded with a NO x An ammonia spraying device is embedded in the reduction zone; The main combustion burner is used to introduce pulverized coal and air and burn in the main combustion zone; the reburning burner is used to introduce a mixed gas of CH4 and NH3 as fuel and burn in the reburning zone, wherein the main combustion zone fuel is pulverized coal and the reburning zone fuel is a mixed gas of CH4 and NH3; the ammonia injection device is used to inject NO x The reduction zone sprays a mixture of ammonia and air to remove the NO x NO in the reduction zone x Perform reduction processing; The main combustion zone fuel accounts for 70-85 wt% of the total fuel, wherein the total fuel is the sum of the main combustion zone fuel and the reburning zone fuel; The ratio of CH4 to NH3 in the reburning zone fuel is β, where Among them, C CH4 represents the mass fraction of methane in the fuel in the reburning zone, C NH3 Indicates the mass fraction of ammonia in the fuel in the reburning zone; The combustion method comprises the following steps: Step 1: When pulverized coal and NH3\CH4 are injected into the boiler through the main combustion burner and the afterburning burner for combustion, overburn air is injected through the overburn air nozzle; Step 2: Real-time monitoring of NO at the exhaust outlet x Concentration, when NO x Concentration below 150 mg / m 3 or higher than 200 mg / m 3 When the NO content of the tail gas outlet is adjusted, the ratio of the reburning zone fuel to the total fuel amount and / or the β value of the reburning zone fuel is adjusted. x Concentration higher than 150 mg / m 3 , but less than 200mg / m 3 ; Step 3: Ammonia injection device to NO x The reduction zone sprays a mixture of ammonia and air, and adjusts the injection amount of the mixed gas to make the NO x Concentration less than 50 mg / m 3 ; In step 2, when the NO x Concentration higher than 200 mg / m 3 When the NO content of the exhaust port is adjusted, the ratio of the reburning zone fuel to the total fuel amount is increased and / or the β value of the reburning zone fuel is reduced. x Concentration below 200 mg / m 3 , but higher than 150mg / m 3 ; When the NO x Concentration below 150 mg / m 3 When the NO content of the exhaust port is adjusted, the ratio of the reburning zone fuel to the total fuel amount is reduced and / or the β value of the reburning zone fuel is increased. x Concentration higher than 150 mg / m 3 , but less than 200mg / m 3 ; When the NO x Concentration higher than 200 mg / m 3 The specific steps of step 2 are as follows: first increase the proportion of reburning zone fuel to the total fuel by 1wt%, if the NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the amount of fuel in the reburning zone is increased by 1 wt%, the NO x The concentration is continuously below 200 mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the proportion of the reburning zone fuel to the total fuel cannot be adjusted to reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 When the β value of the fuel in the reburning zone is lower than 1%, if the exhaust gas outlet is NO x Concentration decreased by 10 mg / m 3 Above, but still higher than 200mg / m 3 When the β value of the fuel in the reburning zone is reduced by 1%, the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration decreased by 10 mg / m 3 Above or cannot be NO x The concentration was reduced to 200 mg / m 3 If the following is true, proceed directly to step 3.

2. The coal and ammonia / methane coupled reburning low nitrogen combustion device according to claim 1 is characterized in that: The excess air coefficient of the reburning zone is 0.75-0.85; the excess air coefficient of the main combustion zone is 1.1-1.5; and the excess air coefficient of the burnout zone is 1.1-1.

3.

3. The coal and ammonia / methane coupled reburning low nitrogen combustion device according to claim 1 is characterized in that: The ammonia content in the mixed gas sprayed from the ammonia spraying device is 3-8% by volume.

4. The coal and ammonia / methane coupled reburning low nitrogen combustion device according to claim 1, characterized in that: The β value is 0.5-1.

5. The coal and ammonia / methane coupled reburning low nitrogen combustion device according to any one of claims 1 to 4, characterized in that: The combustion temperature of the reburning zone is 1200-1400°C; the NO x The reduction zone is located above the burnout zone at a temperature of 850-1100°C.

6. The coal and ammonia / methane coupled reburning low nitrogen combustion device according to any one of claims 1 to 5, characterized in that: When the NO x Concentration below 150 mg / m 3 The specific steps of step 2 are as follows: first reduce the proportion of reburning zone fuel to the total fuel by 1wt%, if the NO x Concentration increased by 10 mg / m 3 Above, but still below 150mg / m 3 When the amount of fuel in the reburning zone is less than 1wt%, the proportion of fuel in the reburning zone to the total fuel will continue to decrease by 1wt% until the NO x Concentrations consistently above 150 mg / m 3 , but less than 200mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the proportion of the reburning zone fuel to the total fuel cannot be adjusted to reduce the NO x Concentration increased by 10 mg / m 3 Above or cannot be NO x Concentration increased to 150 mg / m 3 If the β value of the fuel in the reburning zone is increased by 1%, if the NO x Concentration increased by 10 mg / m 3 Above, but still below 150mg / m 3 When the β value of the fuel in the reburning zone is increased by 1%, the NO x Emission concentration is less than 200mg / m 3 , but higher than 150mg / m 3 If the adjustment exceeds 60 seconds, it is considered that the adjustment is completed; if the adjustment of the β value in the fuel in the reburning zone cannot reduce the NO x Concentration increased by 10 mg / m 3 Above or cannot be NO x Concentration increased to 150 mg / m 3 If the following is true, proceed directly to step 3.

7. A combustion system, characterized in that: The invention comprises a real-time monitoring device (9), an online analysis module, an optimization guidance module and a combustion device according to any one of claims 1 to 6, wherein the real-time monitoring device (9) is used to monitor the NO x concentration, the online analysis module is used to analyze and judge the monitoring results of the real-time monitoring device (9), and the optimization guidance module is used to give instructions for adjusting the proportion of the reburning zone fuel to the total fuel amount, instructions for adjusting the β value, or instructions for directly injecting ammonia from the ammonia injection device based on the analysis results of the online analysis module.

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