Composite combustion device and method for fuel decoupling staged micro-fluidized layer combustion

Abstract

The invention provides a compound combustion device and method for fuel decoupling staged micro-fluidization grate-firing. The compound combustion device comprises a grate-firing furnace and a pyrolysis reactor. The fuel decoupling classification refers to that fine coal particles are converted into pyrolysis gas and high-temperature semi-coke through a cyclone pyrolysis reactor, the pyrolysis gas is introduced from the upper part of a main hearth to be used for reducing nitrogen oxide generated by combustion of a coal bed in a bed layer area, and the high-temperature semi-coke is conveyed to the upper surface of a bed layer through a pipeline to assist in igniting the coal bed; micro-fluidized bed combustion refers to that particle size distribution coal distribution is combined with primary air middle-front part air distribution, fine-particle coal in a bed layer is in a micro-fluidized combustion state in gaps of large-particle coal, combustion and burnout of a bed layer coal sample are enhanced, and the carbon content of bottom slag is reduced; the three-hearth structural design is adopted, fly ash return is coupled, fluidized fly ash and gas-phase components are intensified to be burnt out, and then the carbon content of the fly ash is reduced; through the layer combustion-chamber combustion combined combustion method, the incomplete combustion heat loss of the layer combustion furnace can be effectively reduced, the boiler efficiency is improved, and the original emission of nitrogen oxide is reduced.

Description

Technical Field

[0001] This invention relates to the field of industrial stoker combustion technology, and in particular to a composite combustion device and method for fuel decoupling and staged microfluidic stoker combustion. Background Technology

[0002] my country's actual energy structure is characterized by a "coal-dominated, multi-energy complementary" distribution. Coal resources, facing both opportunities and challenges, will continue to play a dominant role in resource utilization for a considerable period. Stove-fired boilers are widely used in industrial boilers in my country, accounting for 63-65% of the total number of industrial boilers. However, the actual operating efficiency of traditional stove-fired boilers is relatively low (<80%), mainly due to the incomplete combustion of large coal particles on the grate, resulting in high combustible content in slag and fly ash. Furthermore, the initial NO₂ from coal burned in industrial stove-fired boilers... x High emissions mean that NO is currently removed from flue gas using methods such as SNCR and SCR. x Boiler combustion flue gas treatment costs are high. Therefore, exploring new, efficient, and low-pollution combustion methods for industrial stoker furnaces is particularly important, as it not only has enormous potential for energy conservation and emission reduction but also meets the requirements of national environmental protection and energy policies.

[0003] Currently, layered combustion enhancement technology in stoker-fired boilers is widely used, and combined with other composite combustion technologies, it can improve boiler thermal efficiency. Patent CN202010773236.4 discloses a micro-fluidized stoker-fired boiler combustion method. By adjusting the airflow at the bottom of the furnace, the fuel inside the furnace is made to undergo fluidized suspension combustion. Specifically, large particles are in a micro-suspended stoker-fired state, while small particles are in a fluidized combustion state, significantly increasing the combustion speed, enhancing heat transfer on the radiant heating surface, improving stoker-fired efficiency, and reducing the carbon content of ash. However, this patent does not specify the coal distribution method for large and small coal particles, the specific fluidization state, or the air distribution method. Furthermore, to address the issue of high carbon content in fly ash, it is urgent to design a suitable furnace space structure to optimize fly ash burnout. In addition, the coal mining process yields large quantities of finely crushed coal at relatively low prices.

[0004] Therefore, in order to achieve efficient combustion of a high proportion of inexpensive fine coal in a stoker furnace, while reducing the initial NO content of the coal... x For the application of stoker furnaces, it is crucial to design an efficient and low-pollution combined combustion method for stoker combustion, including emission control and in-furnace sulfur suppression. Summary of the Invention

[0005] Given the high carbon content, low thermal efficiency, and NO content in the bottom ash and fly ash of existing industrial coal-fired stoker furnaces, x To address the issue of high initial emissions, this invention provides a composite combustion device and method for fuel decoupling and staged microfluidic stoker combustion, which is expected to simultaneously achieve high-efficiency combustion and low NOx emissions in stoker combustion furnaces. x emission.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a composite combustion device for fuel decoupling staged microfluidic stoker combustion, the composite combustion device comprising a stoker furnace and a pyrolysis reactor;

[0008] The stoker furnace includes a furnace chamber and a grate bed zone. The furnace chamber includes a main furnace chamber, a second furnace chamber, and a third furnace chamber arranged sequentially along the material flow direction. The tops of the main furnace chamber and the second furnace chamber are connected, and the bottoms of the second furnace chamber and the third furnace chamber are connected. The grate bed zone is located below the main furnace chamber, and a first solid phase inlet is provided on the side wall of the grate bed zone.

[0009] The gas phase outlet of the pyrolysis reactor is connected to the gas phase inlet of the main furnace, and the solid phase outlet of the pyrolysis reactor is connected to the second solid phase inlet of the grate bed zone.

[0010] The bottom of the grate bed is provided with a primary air inlet, and the top of the furnace is provided with a secondary air inlet;

[0011] A fly ash recirculation system is provided at the connection between the second and third furnace chambers, and the material outlet of the fly ash recirculation system is connected to the third solid phase inlet of the grate bed zone.

[0012] This invention proposes microfluidized stoker combustion for enhanced combustion in the bed and furnace space zones, cyclone pyrolysis fuel staging, and multi-furnace space coupled fly ash return. It employs a three-furnace structure design with coupled fly ash return to enhance the combustion of fluidized fly ash and gas phase components. The stoker-chamber combustion composite combustion method effectively reduces heat loss from incomplete combustion in stoker furnaces, lowers fly ash carbon content, improves boiler efficiency, and reduces NO. x The original emissions.

[0013] The fly ash recirculation system of the present invention includes a silo pump, a high-pressure gas storage tank, a feed valve, a pressurizing valve, a conveying valve (main gas), a vent valve, a pressure transmitter, a level monitor, etc. A deposited fly ash feed pipeline and a desulfurizing agent feed pipeline are provided above the silo pump. Each of the deposited fly ash feed pipeline and the desulfurizing agent feed pipeline is equipped with a valve. The outlet pipeline of the high-pressure gas storage tank is divided into two branches, both connected to the silo pump. One branch has one valve, and the other branch has two valves. A pipeline is led out between the two valves to the ash storage silo and the main body of the stoker furnace. Preferably, the fly ash recycling ratio accounts for 30%-60% of the mass of deposited fly ash.

[0014] As a preferred technical solution of the present invention, the top of the furnace wall of the main furnace and the second furnace is provided with a flame deflector.

[0015] This invention sets the free space of the stoker furnace as a three-furnace structure, sets a flame deflector in the main furnace, and sets secondary air at the top of the main furnace to enhance the turbulence inside the furnace and increase the combustion residence time of fine coal particles.

[0016] Preferably, the angle between the membrane water-cooled wall surface and the vertical direction in the flame deflector angle is 50-80°, for example, it can be 50°, 55°, 60°, 65°, 70°, 75° or 80°, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 65-75°.

[0017] As a preferred technical solution of the present invention, the connection between the second and third furnace chambers is an inverted triangular structure.

[0018] This invention sets the connection between the second and third furnace chambers as an inverted triangular structure, which is conducive to the deposition of large fly ash particles. At the same time, the fly ash recirculation system circulates unburned fly ash and appropriate high-temperature desulfurizing agent to the upper surface of the grate bed, increasing the residence time of fly ash in the high-temperature zone. This is used to achieve inertial collision separation and efficient combustion of large fly ash particles in the flue gas, while also achieving efficient synchronous desulfurization in the furnace.

[0019] Preferably, the angle of the inverted triangle structure is 45-75°, for example, it can be 45°, 50°, 55°, 60°, 65°, 70° or 75°, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] As a preferred embodiment of the present invention, the pyrolysis reactor includes a cyclone pyrolysis reactor.

[0021] Preferably, 3-9 pyrolysis reactors can be evenly arranged along the width of the stoker furnace, for example, 3, 4, 5, 6, 7, 8 or 9, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 5-7.

[0022] Preferably, the solid phase outlet of the pyrolysis reactor is connected to a discharge pipe, the inner diameter of which is 30-50 mm.

[0023] In this invention, high-temperature semi-coke is transported to the front arch of the firebed by gravity and loosening air through pipes with an inner diameter of 30-50mm under each pyrolysis reactor to accelerate coal seam ignition.

[0024] As a preferred technical solution of the present invention, the primary air supply device includes a wind box.

[0025] In a second aspect, the present invention provides a composite combustion method for fuel decoupling staged microfluidic laminar combustion, wherein the composite combustion method is carried out in the composite combustion apparatus described in the first aspect.

[0026] As a preferred technical solution of the present invention, the composite combustion method includes the following steps:

[0027] Fine-particle coal enters the pyrolysis reactor under air conditions and is converted into pyrolysis gas and high-temperature semi-coke through autothermal pyrolysis. The pyrolysis gas enters the main furnace through the gas phase inlet and mixes with the flue gas generated in the grate bed zone. The high-temperature semi-coke is transported to the grate bed zone through the second solid phase inlet and mixes with the bed zone coal introduced by the first solid phase inlet for micro-fluidized stoker combustion. Under the action of the primary and secondary air, the generated flue gas flows sequentially through the main furnace, the second furnace, and the third furnace. Unburned fly ash is recycled to the fly ash recirculation system and then returns to the high-temperature zone above the grate bed zone for further combustion.

[0028] The fuel decoupling and grading method described in this invention refers to sending the pyrolysis gas generated from coal pyrolysis into the upper part of the furnace through a cyclone pyrolysis reactor to form a local reduction zone, which is used to reduce the NO produced by the combustion of coal samples in the bed. x To achieve NO x Raw emissions are reduced by 40-60%.

[0029] As a preferred embodiment of the present invention, the average particle size of the fine coal particles is <3mm.

[0030] Preferably, the coal in the bed zone includes both large-particle coal and small-particle coal.

[0031] Preferably, the average particle size of the large coal particles is >3 mm.

[0032] Preferably, the average particle size of the small coal particles is ≤3mm.

[0033] The hot fluidization number of the small-particle coal described in this invention is 1-3.

[0034] Preferably, the mass percentage of the small coal particles in the coal in the bed zone is 10-30%, for example, it can be 10%, 15%, 20%, 25% or 30%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the coal feed rate of the pyrolysis reactor accounts for 10-30% of the total coal feed rate of the stoker furnace, for example, it can be 10%, 15%, 20%, 25% or 30%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] This invention achieves microfluidic laminar combustion of coal samples in the bed zone by optimizing the particle size distribution of coal samples coupled with air distribution. It utilizes the microfluidization and scouring effect of small fine coal particles to promote the ignition and burnout of the coal bed.

[0037] As a preferred technical solution of the present invention, the temperature of the self-heating pyrolysis is 400-600℃, for example, it can be 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the air equivalent ratio of the self-heating pyrolysis is 0.2-0.35, for example, it can be 0.2, 0.23, 0.26, 0.29, 0.32 or 0.35, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] As a preferred technical solution of the present invention, in the primary air, the air volume supplied in the middle and front part is 40-60% of the total primary air volume, for example, it can be 40%, 44%, 48%, 52%, 56% or 60%, etc., but is not limited to the listed values. Other unlisted values ​​within the value range are also applicable.

[0040] The air distribution optimization described in this invention refers to using independent air boxes in the bed zone of a stoker furnace and adjusting the air supply ratio of each air box to achieve a front-middle air distribution method. Preferably, the air supply volume in the front-middle section accounts for 40-60% of the total primary air volume. For example, six independent air chambers are set up, and the corresponding air distribution ratios of each air chamber account for 15%, 25%, 25%, 15%, 10%, and 10% of the primary air volume, respectively.

[0041] Preferably, the secondary air volume accounts for 10%-25% of the total air supply volume, for example, it can be 10%, 13%, 16%, 19%, 22% or 25%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] The secondary air described in this invention is arranged in a uniform manner at the middle section of the top of the furnace.

[0043] Preferably, the wind speed of the secondary wind is 15-25 m / s, for example, it can be 15 m / s, 17 m / s, 19 m / s, 21 m / s, 23 m / s or 25 m / s, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] The specific composite combustion method of this invention includes: using a cyclone pyrolysis reactor to autothermally pyrolyze a portion of <3mm fine coal particles under a small amount of air, thereby decomposing them into high-temperature pyrolysis gas and high-temperature semi-coke. The high-temperature pyrolysis gas from the cyclone outlet is piped into the upper part of the main furnace to form a local reduction zone. Under the action of the pyrolysis gas (CO, H2, CH4, NH3, tar vapor, etc.), the coal bed in the bed region is burned to generate NO. x It is reduced to N2, thereby reducing NO, a pollutant from coal combustion.x The original emissions are collected; simultaneously, high-temperature pyrolysis semi-coke is transported through pipelines to the upper surface of the coal seam in front of the bed to assist in accelerating the ignition of the coal seam; the grate bed zone achieves micro-fluidized stoker combustion of the coal sample through coal sample particle size distribution coupled with air distribution optimization, utilizing the micro-fluidization and scouring effect of small fine coal particles to promote the ignition and burnout of large coal particles; for the combustion of the gas-solid phase in the furnace space of the stoker combustion furnace, its free space is set as a three-furnace structure, and a water-cooled wall flame deflector is set in the main furnace, and secondary air is set at the top of the main furnace to enhance the turbulence inside the furnace. This increases the residence time of fine coal particles, thereby enhancing the combustion of the gas-solid phase within the furnace space. To achieve integrated dust removal within the furnace and further reduce the carbon content of fly ash, the connection between the second and third furnace chambers is designed as an inverted triangular structure. This utilizes inertial collision interception to deposit large fly ash particles in the flue gas, effectively achieving efficient dust removal within the furnace. Simultaneously, the unburned fly ash and high-temperature desulfurizing agent are circulated to the rear arch of the main furnace through a fly ash recirculation system, increasing the residence time of fly ash in the high-temperature zone, achieving complete combustion of fly ash, and simultaneously achieving in-furnace desulfurization of the flue gas.

[0045] The high-temperature desulfurizing agent of the present invention can be any one or a combination of at least two of CaO, limestone or dolomite, with a temperature range of 800-950℃ and an in-furnace desulfurization efficiency of 40-60%.

[0046] The fuel decoupling and staged microfluidic stoker-chamber combustion composite combustion method described above is suitable for application in industrial coal-fired stoker furnaces, industrial biomass boilers, etc.

[0047] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0048] (1) In this invention, a cyclone pyrolysis reactor is used to convert some of the fine coal particles <3mm into high-temperature semi-coke and pyrolysis gas. The high-temperature semi-coke is transported to the bed to assist in the combustion of the coal bed. At the same time, the pyrolysis gas fed into the main furnace is rich in reducing gases and NH3, which can effectively reduce the NO produced by the combustion of the coal bed. x It can achieve NO x Primary emissions are reduced by 40-60%, resulting in a reduction of pollutant emissions;

[0049] (2) The bed zone adopts decoupled microfluidic combustion technology, which utilizes the microfluidic effect of 10-30% fine coal particles to enhance the ignition of large coal particles and significantly improve the combustion rate of the coal bed. As combustion progresses, fine coal particles enter the furnace space zone to increase the porosity of the coal bed, while continuously flushing out large coal particles to enhance the burnout of the large coal particles, thus achieving a bottom ash carbon content of <8%;

[0050] (3) Through the design of the three-furnace space and the flame deflector angle, the combustion path of unburned fine coal entering the furnace can be increased by more than two times. At the same time, combined with the fly ash recirculation system, the unburned fly ash and desulfurizing agent are recycled to the main furnace for re-combustion, which can further improve the problem of high carbon content in fly ash and complete in-furnace desulfurization at the same time, so as to reduce the carbon content of fly ash to below 6% and the in-furnace desulfurization efficiency >50%;

[0051] (4) The composite combustion method of the stoker furnace proposed in this invention can simultaneously reduce the carbon content of bottom ash and fly ash, reduce the heat loss from incomplete combustion in the boiler, and significantly improve the boiler thermal efficiency to over 87%. At the same time, through fuel decoupling and grading, inertial collision deposition of fly ash particles in the furnace, and in-furnace calcium injection, efficient combustion of coal and low NO2 in the furnace can be achieved. x -Integrated operation of sulfur suppression and dust removal reduces the operating costs of subsequent SCR denitrification, bag filter dust collection and external wet desulfurization. Attached Figure Description

[0052] Figure 1 A schematic diagram of the fuel decoupling staged microfluidic laminar combustion composite combustion method provided by the present invention;

[0053] Figure 2 A schematic diagram of the microfluidized stoker coal distribution method in the stoker furnace bed provided by the present invention;

[0054] Figure 3 This is a schematic diagram of the fly ash recycling and reburning conveying system provided by the present invention;

[0055] Among them, 1-layer combustion furnace grate; 2-primary air chamber; 3-coal hopper; 4-cyclone pyrolysis reactor; 5-main furnace; 6-secondary air nozzle; 7-flame deflector; 8-secondary furnace; 9-fly ash circulation nozzle; 10-tail flue of the third furnace. Detailed Implementation

[0056] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0057] It should be clarified that any use of the process provided in the embodiments of the present invention or any substitution or change of conventional data falls within the protection and disclosure scope of the present invention.

[0058] Example 1

[0059] This embodiment provides a composite combustion device for fuel decoupling staged microfluidic stoker combustion. The composite combustion device includes a stoker furnace and a cyclone pyrolysis reactor 4. Five pyrolysis reactors 4 are evenly arranged along the width direction of the stoker furnace.

[0060] The stoker furnace includes a furnace chamber and a grate bed zone. The furnace chamber includes a main furnace chamber 5, a second furnace chamber 8, and a third furnace chamber 10 arranged sequentially along the material flow direction. The main furnace chamber 5 and the second furnace chamber 8 are connected at the top, and the top of the furnace wall is provided with a 70° flame deflector angle 7. The second furnace chamber 8 and the third furnace chamber 10 are connected at the bottom, and the connection is an inverted triangular structure. The grate bed zone is located below the main furnace chamber 5. The side wall of the grate bed zone is provided with a first solid phase inlet coal hopper 3, and the stoker furnace grate 1 is provided inside.

[0061] The gas phase outlet of the cyclone pyrolysis reactor 4 is connected to the gas phase inlet of the main furnace 5, and the solid phase outlet of the cyclone pyrolysis reactor 4 is connected to the second solid phase inlet of the grate bed zone.

[0062] The bottom of the grate bed area is provided with 8 independent primary air chambers 2, and the top of the furnace is evenly arranged with 7 secondary air nozzles 6;

[0063] A fly ash recirculation system is provided at the connection between the second furnace 8 and the third furnace 10, such as... Figure 3 As shown, the fly ash recirculation system includes a silo pump, a high-pressure gas storage tank, a feed valve, a pressurizing valve, a conveying valve (main gas), a venting valve, a pressure transmitter, a material level monitor, etc. The material outlet of the fly ash recirculation system is connected to the third solid phase inlet fly ash circulation nozzle 9 of the grate bed zone.

[0064] Example 2

[0065] This embodiment provides a composite combustion device for fuel decoupling and staged microfluidic laminar combustion. The only difference between the composite combustion device and Embodiment 1 is that the top of the furnace wall separating the main furnace and the secondary furnace is not provided with a flame deflector. All other aspects are the same as in Application Example 1.

[0066] Comparative Example 1

[0067] This comparative example provides a composite combustion device for fuel decoupling staged microfluidic stoker combustion. The only difference between the composite combustion device and Example 1 is that the composite combustion device does not have a pyrolysis reactor and only includes a stoker furnace. All other aspects are the same as in Example 1.

[0068] Application Example 1

[0069] This application example provides a hybrid combustion method for fuel decoupling and staged microfluidic laminar combustion. The hybrid combustion method is performed in the hybrid combustion apparatus provided in Example 1, and includes the following steps:

[0070] Fine-grained bituminous coal with a particle size of <3mm enters the pyrolysis reactor under air conditions. It undergoes self-heating pyrolysis by introducing air with an equivalent ratio of 0.30 into the bottom of the cyclone pyrolysis reactor, converting it into pyrolysis gas and high-temperature semi-coke. The cyclone pyrolysis temperature is stabilized at 500℃.

[0071] Pyrolysis gas is introduced into the side wall of the main furnace through a pipeline and mixed with the flue gas generated in the grate bed zone. High-temperature pyrolysis semi-coke is transported to the upper surface of the coal bed in the bed zone through a 40mm inner diameter pipeline to accelerate the ignition of the coal bed. The coal particle size range in the bed zone is 0-30mm, of which small coal particles <3mm account for 30% of the coal feed in the bed zone. The coal feed of the pyrolysis reactor accounts for 30% of the total coal feed of the stoker furnace. Under the action of the primary and secondary air, the generated flue gas flows sequentially through the main furnace, the second furnace, and the third furnace.

[0072] The primary air system is divided into eight independent air chambers. The opening of each air chamber is adjusted so that the air distribution ratios are 10%, 16%, 25%, 18%, 10%, 10%, 6%, and 5% respectively, forming a mid-front air distribution method. This ensures that the thermal fluidization number of fine coal particles in the gaps between large coal particles is between 1 and 3, and that the fine coal particles are evenly distributed in the gaps between the large coal particles. Preheated hot air is blown in from the bottom of each air chamber of the grate, causing the fine coal particles to form a micro-fluidized combustion state. The secondary air volume accounts for 15% of the total air supply volume, and the air velocity is set to 20 m / s.

[0073] After unburned fly ash is recycled to the fly ash recirculation system, it returns to the grate bed area and periodically releases the deposited fly ash into the silo pump at a cycle of 30 minutes. Through the silo pump system, 40% of the deposited fly ash is sent back to the rear arch of the furnace under the action of high-pressure air. The connecting pipes are evenly distributed, and the remaining fly ash is directly transported to the ash storage silo to achieve in-furnace dust removal, reduce the processing load of the subsequent bag filter, and achieve further combustion.

[0074] Application Example 2

[0075] This application example provides a composite combustion method for fuel decoupling and staged microfluidic laminar combustion. The only difference between this composite combustion method and Application Example 1 is that the coal type is changed to Shenmu bituminous coal, while the rest is the same as Application Example 1.

[0076] Application Example 3

[0077] This application example provides a composite combustion method for fuel decoupling and staged microfluidic stoker combustion. The only difference between this composite combustion method and Application Example 1 is that the coal type is changed to lignite, while the rest is the same as Application Example 1.

[0078] Application Example 4

[0079] This application example provides a composite combustion method for fuel decoupling and staged microfluidic laminar combustion. The only difference between this composite combustion method and Application Example 1 is that the mass fraction of small particulate coal samples in the bed feed is changed to 40%, while the rest are the same as in Application Example 1.

[0080] Application Example 5

[0081] This application example provides a composite combustion method for fuel decoupling and staged microfluidic laminar combustion. The only difference between this composite combustion method and Application Example 1 is that the coal in the bed zone consists entirely of large-particle coal and does not contain small-particle coal. All other aspects are the same as in Application Example 1.

[0082] Application Example 6

[0083] This application example provides a composite combustion method for fuel decoupling staged microfluidic laminar combustion. The composite combustion method is carried out in the composite combustion device provided in Example 2, and the remaining process parameters are the same as in Application Example 1.

[0084] Comparative Application Example 1

[0085] This application example provides a composite combustion method of fuel decoupled staged microfluidic stoker combustion, which is carried out in the composite combustion device provided in Comparative Example 1, and the process parameters in the stoker furnace are the same as those in Application Example 1.

[0086] Performance testing

[0087] The composite combustion method provided in the application example was tested, and after stable operation, samples were taken and measured for bottom ash, fly ash, thermal efficiency, and NO. x The emission results are shown in Table 1.

[0088] Table 1

[0089]

[0090] As shown in Table 1, this invention employs a particle size distribution of coal combined with pre-primary air distribution, resulting in a micro-fluidized combustion state of fine coal particles within the gaps between larger coal particles in the bed. This enhances the combustion and burnout of the bed coal sample, reducing the carbon content of the bottom ash. Simultaneously, a three-furnace structure design coupled with fly ash return enhances the burnout of fluidized fly ash and gaseous components, further reducing the carbon content of the fly ash. Through the stoker-chamber combustion composite combustion method proposed in this invention, the heat loss from incomplete combustion in stoker furnaces can be effectively reduced, boiler efficiency improved, and NOx levels reduced. x The original emissions.

[0091] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A composite combustion device for fuel decoupling staged microfluidic laminar combustion, characterized in that, The composite combustion device includes a stoker furnace and a pyrolysis reactor; The stoker furnace includes a furnace chamber and a grate bed zone. The furnace chamber includes a main furnace chamber, a second furnace chamber, and a third furnace chamber arranged sequentially along the material flow direction. The tops of the main furnace chamber and the second furnace chamber are connected, and the bottoms of the second furnace chamber and the third furnace chamber are connected. The grate bed zone is located below the main furnace chamber, and a first solid phase inlet is provided on the side wall of the grate bed zone. The gas phase outlet of the pyrolysis reactor is connected to the gas phase inlet of the main furnace, and the solid phase outlet of the pyrolysis reactor is connected to the second solid phase inlet of the grate bed zone. The bottom of the grate bed is provided with a primary air inlet, and the top of the furnace is provided with a secondary air inlet; A fly ash recirculation system is provided at the connection between the second and third furnace chambers, and the material outlet of the fly ash recirculation system is connected to the third solid phase inlet of the grate bed zone.

2. The composite combustion device according to claim 1, characterized in that, The top of the furnace wall separating the main furnace chamber and the second furnace chamber is provided with a flame deflector. Preferably, the angle between the membrane water-cooled wall surface and the vertical direction in the flame deflector is 50-80°, and more preferably 65-75°.

3. The composite combustion device according to claim 1 or 2, characterized in that, The connection between the second and third furnace chambers is an inverted triangular structure. Preferably, the angle of the inverted triangular structure is 45-75°.

4. The composite combustion device according to any one of claims 1 to 3, characterized in that, The pyrolysis reactor includes a cyclone pyrolysis reactor; Preferably, 3-9 pyrolysis reactors are evenly arranged along the width of the stoker furnace, and more preferably 5-7. Preferably, the solid phase outlet of the pyrolysis reactor is connected to a discharge pipe, the inner diameter of which is 30-50 mm.

5. The composite combustion device according to any one of claims 1 to 4, characterized in that, The primary air supply device includes a bellows.

6. A composite combustion method for fuel decoupling and staged microfluidic laminar combustion, characterized in that, The composite combustion method is performed in the composite combustion apparatus as described in any one of claims 1 to 5.

7. The composite combustion method according to claim 6, characterized in that, The composite combustion method includes the following steps: Fine-particle coal enters the pyrolysis reactor under air conditions and is converted into pyrolysis gas and high-temperature semi-coke through autothermal pyrolysis. The pyrolysis gas enters the main furnace through the gas phase inlet and mixes with the flue gas generated in the grate bed zone. The high-temperature semi-coke is transported to the grate bed zone through the second solid phase inlet and mixes with the bed zone coal introduced by the first solid phase inlet for micro-fluidized stoker combustion. Under the action of the primary and secondary air, the generated flue gas flows sequentially through the main furnace, the second furnace, and the third furnace. Unburned fly ash is recycled to the fly ash recirculation system and then returns to the high-temperature zone above the grate bed zone for further combustion.

8. The composite combustion method according to claim 6 or 7, characterized in that, The average particle size of the fine coal is <3mm; Preferably, the coal in the bed zone includes large-particle coal and small-particle coal; Preferably, the average particle size of the large coal particles is >3 mm; Preferably, the average particle size of the small coal particles is ≤3mm; Preferably, the small-particle coal accounts for 10-30% of the total mass of the coal in the bed zone; Preferably, the coal feed rate of the pyrolysis reactor accounts for 10-30% of the total coal feed rate of the stoker.

9. The composite combustion method according to any one of claims 6 to 8, characterized in that, The temperature of the self-heating pyrolysis is 400-600℃; Preferably, the air equivalence ratio of the self-heating pyrolysis is 0.2-0.

35.

10. The composite combustion method according to any one of claims 6 to 9, characterized in that, In the primary airflow, the air volume supplied to the front and middle sections accounts for 40-60% of the total primary airflow. Preferably, the secondary air volume accounts for 10%-25% of the total air supply volume; Preferably, the wind speed of the secondary wind is 15-25 m / s.

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