CN-122015082-A - Composite combustion device and method for fuel decoupling grading microfluidization layer combustion

CN122015082ACN 122015082 ACN122015082 ACN 122015082ACN-122015082-A

Abstract

The invention provides a composite combustion device and a method for fuel decoupling grading microfluidization layer combustion, wherein the composite combustion device comprises a layer combustion furnace and a pyrolysis reactor, the fuel decoupling grading refers to converting fine coal particles into pyrolysis gas and high-temperature semicoke through the cyclone pyrolysis reactor, the pyrolysis gas is introduced from the upper part of a main hearth to reduce nitrogen oxides generated by coal layer combustion in a bed area, the high-temperature semicoke is transmitted to the upper surface of the bed layer through a pipeline to assist in igniting the coal layer, the microfluidization layer combustion refers to adopting particle size-grade distributed coal to be combined with front air distribution in primary air, fine particle coal in the bed layer is in a microfluidization combustion state in a large particle coal gap, the combustion and burnout of a bed coal sample are enhanced, the carbon content of bottom slag is reduced, the coupling of a three-hearth structure is adopted to enhance the combustion of fluidization and gas phase components, and the carbon content of the fly ash is further reduced, and through the combustion-chamber combustion composite 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 oxides is reduced.

Inventors

LI SONGGENG
DING GUANGCHAO
Ding Guangjie
ZHU LIANG
ZHANG HONGYAN

Assignees

中国科学院过程工程研究所
新疆煤炭清洁燃烧与储能研发中心有限公司
和布克赛尔蒙古自治县华源热力有限公司

Dates

Publication Date: 20260512
Application Date: 20260323

Claims (10)

1. A fuel decoupling graded microfluidization layer combustion composite combustion device, which is characterized by comprising a layer combustion furnace and a pyrolysis reactor; The grate-fired furnace comprises a furnace chamber and a grate bed region, wherein the furnace chamber comprises a main furnace chamber, a second furnace chamber and a third furnace chamber which are sequentially arranged along the material flow direction, the tops of the main furnace chamber and the second furnace chamber are communicated, the bottoms of the second furnace chamber and the third furnace chamber are communicated, the grate bed region is positioned below the main furnace chamber, and a first solid phase inlet is formed in the side wall of the grate bed region; The gas phase outlet of the pyrolysis reactor is connected with the gas phase inlet of the main hearth, and the solid phase outlet of the pyrolysis reactor is connected with the second solid phase inlet of the grate bed zone; the bottom of the grate bed zone is provided with a primary air inlet, and the top of the hearth is provided with a secondary air inlet; And a fly ash recycling system is arranged at the joint of the two hearths and the three hearths, and a material outlet of the fly ash recycling system is connected with a third solid phase inlet of the fire grate bed zone.
2. The composite combustion apparatus according to claim 1, wherein a fold flame angle is provided at a top of a furnace wall separating the main furnace and the two furnaces; Preferably, the included angle between the membrane water-cooled wall surface in the folded flame angle and the vertical direction is 50-80 degrees, preferably 65-75 degrees.
3. The composite combustion apparatus according to claim 1 or 2, wherein the junction of the two hearths and the three hearths is of an inverted triangle structure; Preferably, the angle of the inverted triangle is 45-75 °.
4. A composite combustion apparatus according to any one of claims 1 to 3, wherein the pyrolysis reactor comprises a cyclone pyrolysis reactor; Preferably, the pyrolysis reactors may be uniformly arranged in the width direction of the grate-fired furnace in 3 to 9, preferably 5 to 7; preferably, a solid phase outlet of the pyrolysis reactor is connected with a discharge pipeline, and the inner diameter of the discharge pipeline is 30-50mm.
5. The composite combustion apparatus according to any one of claims 1 to 4, wherein the primary air supply means comprises a bellows.
6. A composite combustion method of fuel decoupling and staged microfluidization layer combustion, characterized in that the composite combustion method is carried out in a composite combustion device according to any one of claims 1 to 5.
7. The composite combustion method of claim 6, wherein the composite combustion method comprises the steps of: The fine particle coal enters the pyrolysis reactor under the air condition and is converted into pyrolysis gas and high-temperature semicoke through self-heating pyrolysis, the pyrolysis gas enters the main hearth through the gas phase inlet and is mixed with smoke generated in the fire grate bed zone, the high-temperature semicoke is conveyed to the fire grate bed zone through the second solid phase inlet and is mixed with the coal in the bed zone introduced by the first solid phase inlet to carry out microfluidization layer combustion enhanced combustion, the generated smoke sequentially flows through the main hearth, the second hearth and the third hearth under the action of primary air and secondary air, and unburned fly ash returns to the high-temperature zone above the fire grate bed zone again after being circulated to the fly ash recirculation system, so that further combustion is realized.
8. The composite combustion method according to claim 6 or 7, wherein the fine particle coal has an average particle diameter of <3mm; Preferably, the bed zone coal comprises large particle coal and small particle coal; preferably, the large particle coal has an average particle size >3mm; preferably, the average particle size of the small particle coal is less than or equal to 3mm; Preferably, the mass ratio of the small particle coal in the bed zone coal is 10-30%; preferably, the coal feeding amount of the pyrolysis reactor accounts for 10-30% of the total coal feeding amount of the grate-fired furnace.
9. The composite combustion method according to any one of claims 6 to 8, wherein the temperature of the autothermal pyrolysis is 400-600 ℃; preferably, the autothermal pyrolysis has an air equivalence ratio of 0.2 to 0.35.
10. The composite combustion method according to any one of claims 6 to 9, wherein the air supply amount in the middle front part of the primary air is 40 to 60% of the total amount of the primary air; preferably, the secondary air volume accounts for 10% -25% of the total air volume; Preferably, the wind speed of the secondary wind is 15-25m/s.

Description

Composite combustion device and method for fuel decoupling grading microfluidization layer combustion Technical Field The invention relates to the technical field of industrial grate-fired furnace combustion, in particular to a fuel decoupling graded microfluidization grate-fired composite combustion device and method. Background The actual energy structure in China is distributed in a way of 'mainly using coal and complementarily providing multiple functions', and the resource utilization of the coal resource is still in continuous occupation in a long time in the future. The layer combustion furnace in China is quite extensive in the use of industrial boilers, and accounts for 63-65% of the total number of the industrial boilers. However, the actual operating efficiency of the traditional grate-fired furnace is lower (< 80%), mainly because large-particle coal on the grate cannot be fully burned out, and the combustible content of slag and fly ash is higher. In addition, the emission of the original NO x of the industrial grate-fired furnace coal is high, NO x in the flue gas is removed through SNCR, SCR and other modes at present, and the treatment cost of the boiler combustion flue gas is high. Therefore, it is important to explore a novel efficient low-pollution combustion mode of the industrial grate-fired furnace, so that the novel efficient low-pollution combustion mode has huge energy saving and emission reduction potential, and can meet the national environmental protection and energy policy requirements. At present, the layer-by-layer combustion enhancement technology of the layer-combustion hearth layer is widely applied, and the thermal efficiency of the boiler can be improved by combining with the compound combustion technology of other modes. Patent CN202010773236.4 discloses a combustion method of a microfluidization layer combustion boiler, by adjusting the air supply quantity at the bottom of a hearth, fuel in the hearth is in a fluidization suspension state for combustion, specifically, large particles are in a microsuspension layer combustion state, small particles are in a fluidization combustion state, the combustion speed is greatly improved, the heat transfer of a radiation heating surface is enhanced, the layer combustion efficiency is improved, and the carbon content of ash slag is reduced, however, the patent does not define a coal sample coal distribution mode of large and small particles, a specific fluidization state and an air distribution mode, and meanwhile, the problem of high carbon content of fly ash is urgent to design a proper hearth space structure to optimize the fly ash for combustion. Therefore, in order to better realize the high-efficiency combustion of high-proportion cheap fine coal in the grate-fired furnace, and simultaneously reduce the original NO x emission of the coal and the sulfur inhibition in the furnace, the design of the high-efficiency low-pollution grate-fired-chamber-fired composite combustion mode is important for the grate-fired furnace application. Disclosure of Invention In view of the problems of high carbon content in the bottom slag and fly ash of the existing industrial coal-fired grate-fired furnace, low operating thermal efficiency and high original emission of NO x, the invention provides a fuel decoupling graded microfluidization grate-fired composite combustion device and a method, which are expected to realize the efficient combustion and the low emission of NO x of the grate-fired furnace at the same time. To achieve the purpose, the invention adopts the following technical scheme: in a first aspect, the present invention provides a fuel-decoupled staged microfluidized layered combustion apparatus comprising a layered combustion furnace and a pyrolysis reactor; The grate-fired furnace comprises a furnace chamber and a grate bed region, wherein the furnace chamber comprises a main furnace chamber, a second furnace chamber and a third furnace chamber which are sequentially arranged along the material flow direction, the tops of the main furnace chamber and the second furnace chamber are communicated, the bottoms of the second furnace chamber and the third furnace chamber are communicated, the grate bed region is positioned below the main furnace chamber, and a first solid phase inlet is formed in the side wall of the grate bed region; The gas phase outlet of the pyrolysis reactor is connected with the gas phase inlet of the main hearth, and the solid phase outlet of the pyrolysis reactor is connected with the second solid phase inlet of the grate bed zone; the bottom of the grate bed zone is provided with a primary air inlet, and the top of the hearth is provided with a secondary air inlet; And a fly ash recycling system is arranged at the joint of the two hearths and the three hearths, and a material outlet of the fly ash recycling system is connected with a third solid phase inlet of the fire grate bed zone. The invention provides m