CN114923168A - Self-stabilized low-nitrogen-oxide four-corner tangential boiler and combustion method - Google Patents
Self-stabilized low-nitrogen-oxide four-corner tangential boiler and combustion method Download PDFInfo
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- CN114923168A CN114923168A CN202210536041.7A CN202210536041A CN114923168A CN 114923168 A CN114923168 A CN 114923168A CN 202210536041 A CN202210536041 A CN 202210536041A CN 114923168 A CN114923168 A CN 114923168A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
- F23C5/08—Disposition of burners
- F23C5/10—Disposition of burners to obtain a flame ring
- F23C5/12—Disposition of burners to obtain a flame ring for pulverulent fuel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C7/00—Combustion apparatus characterised by arrangements for air supply
- F23C7/02—Disposition of air supply not passing through burner
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Abstract
The invention provides a self-stable combustion low-nitrogen oxide four-corner tangential boiler system and a combustion method, wherein the four-corner tangential boiler system comprises an entrained-flow bed gasification furnace and a four-corner tangential boiler, the four-corner tangential boiler comprises a burner nozzle, and the burner nozzle comprises a primary air nozzle; the entrained-flow bed gasification furnace is communicated with the tangential firing boiler at four corners through a synthesis gas channel, synthesis gas outlets and primary air nozzles are distributed on the four corners of the tangential firing boiler at four corners, the synthesis gas channel is connected with the synthesis gas outlets, and the heights of the synthesis gas outlets and the primary air nozzles are the same; the central lines of the synthetic gas outlet and the primary air nozzle are respectively tangent to one or more imaginary tangential circles in the four-corner tangential boiler, and the diameter of the synthetic gas outlet corresponding to the imaginary tangential circles is smaller than that of the primary air nozzle corresponding to the imaginary tangential circles. The four-corner tangential boiler system provided by the invention has the advantages of good combustion stabilizing effect at low load, low emission concentration of nitrogen oxides and good burnout performance.
Description
Technical Field
The invention relates to the technical field of boiler combustion, in particular to a self-stabilized low-nitrogen oxide four-corner tangential boiler and a combustion method.
Background
Based on the characteristics of 'more coal, lean oil and less gas' of the energy structure in China, the main energy supply status of coal is kept unchanged for a long time. The coal consumption of the thermal power generation at present accounts for more than 60 percent of the total coal consumption of China. The burners of the four-corner tangential boiler are arranged at four corners of a tangent plane of a hearth, a rotating aerodynamic field is formed in the furnace through jet flows at the four corners, a rotating stable combustion area is formed in the furnace, the hearth is high in fullness degree/combustion efficiency, and therefore the four-corner tangential boiler is generally applied to a thermal power plant.
However, the four-corner tangential boiler in the prior art has the problems of poor stable combustion at low load, incapability of realizing flexible peak regulation, high and best nitrogen oxide emission concentration and the like, is not beneficial to realizing carbon peak reaching and carbon neutralization, and is easy to cause great pollution to the environment.
Disclosure of Invention
The invention aims to provide the four-corner tangential boiler which has good stable combustion effect at low load, low nitrogen oxide emission concentration and good burnout performance.
In order to solve the problems, the invention provides a corner tangential boiler system capable of realizing self-stable combustion and low nitrogen oxide, which comprises an entrained flow gasifier and a corner tangential boiler, wherein the corner tangential boiler comprises a burner nozzle, and the burner nozzle comprises a primary air nozzle; the entrained-flow bed gasifier is communicated with the tangential firing boiler through a synthesis gas channel, synthesis gas outlets and the primary air nozzles are distributed on four corners of the tangential firing boiler, the synthesis gas channel is connected with the synthesis gas outlets, and the synthesis gas outlets and the primary air nozzles are the same in height; the central lines of the synthetic gas outlet and the primary air nozzle are respectively tangent to one or more imaginary tangent circles in the four-corner tangential boiler, and the diameter of the synthetic gas outlet corresponding to the imaginary tangent circle is smaller than that of the primary air nozzle corresponding to the imaginary tangent circle.
Preferably, the side surface of the synthesis gas outlet is provided with a rectangular protrusion, the side surface of the primary air nozzle is provided with a rectangular recess, and the synthesis gas outlet and the primary air nozzle are mutually embedded through the rectangular protrusion and the rectangular recess.
Preferably, the synthetic gas export with contained angle between the central line of a wind spout is alpha, in a wind spout the quantity of rectangle concave recess is n, the degree of depth of rectangle concave recess is h, the thickness of rectangle concave recess is b, just the rectangle concave recess is in evenly distributed on the wind spout, the area of synthetic gas export is A 1 The area of the primary air nozzle is A 2 The area of the rectangular recess is A 3 (ii) a When burning coal type V daf When more than 20%, alpha is 0-6 deg., n is 0, 1 or 2, b is 20-30 mm, h is 1-1.5 b, A 1 ＝0.35～0.5A 2 ，A 3 ＝0～5％A 2 (ii) a When burning coal, V is less than or equal to 10% daf Not more than 20%, alpha is 5-9 deg., n is 2 or 3, b is 25-35 mm, h is 1.5-2.5 b, A 1 ＝0.4～0.5A 2 ，A 3 ＝3～15％A 2 (ii) a When burning coal type V daf <10% of the total of a, 5 to 12 °, 3 or 4 for n, 25 to 35mm for b, 2.5 to 4b for h, A 1 ＝0.4～0.5A 2 ，A 3 ＝10～22％A 2 。
Preferably, the self-stable combustion low-nitrogen oxide four-corner tangential boiler system further comprises a radiation waste boiler and a slag pool, the entrained flow gasifier is sequentially connected with the radiation waste boiler and the slag pool from top to bottom, and the radiation waste boiler is communicated with the four-corner tangential boiler through the synthesis gas channel.
Preferably, the height of the entrained-flow gasifier is H 1 The height of the radiation waste pot is H 2 And H is 1 ＝0.2～0.35H 2 。
Preferably, the burner nozzle further comprises a secondary air nozzle when burning coal V daf When the air flow rate is more than or equal to 10%, the primary air nozzles and the secondary air nozzles are arranged in an equal air distribution mode, and the primary air nozzles and the secondary air nozzles are arranged alternately; when burning coal type V daf And when the air flow rate is less than 10%, primary air is intensively arranged, and the primary air nozzles are intensively arranged together.
Preferably, water-cooled walls are distributed around the four-corner tangential boiler.
According to the invention, the pulverized coal is gasified into the crude synthesis gas through the entrained-flow bed gasification furnace, the crude synthesis gas and the primary air pulverized coal airflow entering the primary air nozzle are simultaneously sprayed into the four-corner tangential boiler, so that the crude synthesis gas and the primary air pulverized coal airflow are fully mixed, the ignition is rapidly finished, and the stable combustion is finally realized, and after the high-temperature crude synthesis gas sprayed in the synthesis gas channel and the primary air pulverized coal airflow with higher oxygen content sprayed in the primary air nozzle are mixed in the four-corner tangential boiler, the high-temperature crude synthesis gas can be rapidly ignited, and the primary air pulverized coal airflow is also ignited, so that the ignition of the primary air pulverized coal airflow sprayed in the primary air nozzle is not influenced by the temperature of a hearth, and the low-load stable combustion can be realized; the synthetic gas outlets and the primary air nozzles are distributed at four corners of the boiler with four tangential corners, and the central lines of the synthetic gas outlets and the primary air nozzles are respectively tangent to one or more imaginary tangential circles in a boiler furnace, when the coarse synthetic gas and primary air pulverized coal airflow sprayed from one corner are combusted, the airflow of the adjacent corners at the downstream can be ignited, and finally the airflow at the four corners is all ignited with each other; in addition, the primary air pulverized coal airflow sprayed from the primary air nozzle is ignited by the crude synthesis gas, so that the combustion time of the primary air pulverized coal airflow is longer, the proportion of fire coal is reduced by mixing the primary air pulverized coal airflow with the crude synthesis gas, and the burnout property is improved.
Another object of the present invention is to provide a combustion method of the above four-corner tangential boiler system for self-stabilized combustion of low nitrogen oxides, wherein a entrained-flow gasifier is used to generate a crude synthesis gas, the crude synthesis gas is injected into the four-corner tangential boiler through a synthesis gas channel, a primary air pulverized coal gas flow is injected into the four-corner tangential boiler through a primary air nozzle, and the crude synthesis gas and the primary air pulverized coal gas flow are simultaneously injected into the four-corner tangential boiler.
Preferably, the rough jointThe resultant gas comprises CO and H 2 、O 2 、CO 2 、H 2 O and ash, wherein the CO and the H are in volume fraction 2 85-88% of the total weight of the composition, and O 2 The ratio is less than 0.5%.
Preferably, the mass ratio of the raw synthesis gas to the primary air pulverized coal flow is 0.4-0.45: 1.
Compared with the prior art, the combustion method provided by the invention has the same beneficial effect as a four-corner tangential filtration system for self-stabilized combustion of low nitrogen oxides, and the description is omitted.
Description of the drawings:
FIG. 1 is a schematic structural diagram of a corner tangential boiler system for self-stabilized combustion of low NOx in an embodiment of the present invention;
FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;
FIG. 3 is a schematic diagram of the mutual engagement structure of the syngas outlet and the primary air nozzle in the embodiment of the invention:
FIG. 4 is a schematic structural diagram of a synthesis gas outlet and a primary air nozzle in the embodiment of the invention;
FIG. 5 is a schematic view showing the structure of a gasification furnace in the prior art.
Description of reference numerals:
1. an entrained flow gasifier; 2. a boiler with four tangential corners; 21. a boiler furnace; 22. a burner nozzle; 221. a primary air nozzle; 2211. a rectangular recess; 222. a secondary air nozzle; 3. a syngas channel; 31. a syngas outlet; 311. a rectangular protrusion; 4. radiating the waste boiler; 5. a slag pool; 6. a gasification chamber; 7. a quench chamber; 71. a chilling water pipe; 711. a quench ring.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments thereof are described in detail below.
It should be noted that the features in the embodiments of the present invention may be combined with each other without conflict. The terms "comprising", "including", "containing" and "having" are intended to be non-limiting, i.e., that other steps and other ingredients can be added which do not affect the result. The above terms encompass the terms "consisting of … …" and "consisting essentially of … …". Materials, equipment and reagents are commercially available unless otherwise specified.
As shown in fig. 1 and fig. 2, the embodiment of the invention provides a corner tangential boiler system for self-stabilized combustion of low nitrogen oxides, comprising an entrained flow gasifier 1 and a corner tangential boiler 2, wherein the corner tangential boiler 2 comprises a burner nozzle 22, and the burner nozzle 22 comprises a primary air nozzle 221; the entrained-flow gasifier 1 is communicated with the four-corner tangential boiler 2 through a synthesis gas channel 3, synthesis gas outlets 31 and the primary air nozzles 221 are distributed at four corners of the four-corner tangential boiler 2, the synthesis gas channel 3 is connected with the synthesis gas outlets 31, and the synthesis gas outlets 31 and the primary air nozzles 221 are the same in height; the central lines of the synthetic gas outlet 31 and the primary air nozzle 221 are respectively tangent to one or more imaginary tangential circles in the four-corner tangential boiler 2, and the diameter of the synthetic gas outlet 31 corresponding to the imaginary tangential circles is smaller than that of the primary air nozzle 221 corresponding to the imaginary tangential circles.
The four-corner tangential boiler 2 comprises a boiler furnace 21 and a burner nozzle 22, the burner nozzle 22 comprises a primary air nozzle 221, the primary air nozzle 221 is suitable for spraying mixed gas of pulverized coal and air, a synthetic gas outlet 31 is suitable for spraying crude synthetic gas generated by the entrained-flow bed gasification furnace 1, and a plurality of synthetic gas outlets 31 and a plurality of primary air nozzles 221 are distributed at four corners of the boiler furnace 21 of the four-corner tangential boiler 2.
It should be understood that the syngas channel 3 is connected to a plurality of syngas outlets 31 distributed at four corners of the corner tangential firing boiler 2 and uniformly sprays the raw syngas generated in the entrained-flow gasifier 1 through the plurality of syngas outlets 31.
Illustratively, the diameter of the imaginary circle of tangency for the syngas outlet 31 is 0.6-1 m, and the diameter of the imaginary circle of tangency for the primary air nozzle 221 is 1-1.5 m.
The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention can improve the self-stabilizing combustion performance. The method comprises the following specific steps:
of boilers with tangential four corners in the prior artThe burners are direct-current burners, the burners are distributed at four corners of the hearth, and airflow sprayed by the four burners forms an imaginary tangent circle at the center of the hearth. The boiler with tangential circle at four corners can select bituminous coal, lean coal or anthracite as fuel, wherein V of the bituminous coal daf Volatile component more than 20%, V less than 10% of lean coal daf V of anthracite coal less than or equal to 20 percent daf The ignition temperature of the bituminous coal is less than 10 percent, the ignition temperature of the bituminous coal is 400-550 ℃, the lithofacies structures of the lean coal and the anthracite are compact and stable, the porosity is small, the reactivity is low, the ignition temperature is higher, the ignition distance is longer, and the ignition temperature of the gas is 450-750 ℃.
Illustratively, the airflow ejected by the four burners forms an imaginary tangent circle with the diameter of 0.6-1.5 m at the center of the hearth. The ignition distance is 0.7-1.2 m when bituminous coal is used, 1-1.4 m when lean coal is used, and 1.5-1.7 m when anthracite coal is used. When the boiler is in high-load operation, the flue gas temperature of a hearth is 1200-1400 ℃, and after primary air pulverized coal airflow enters the hearth, the primary air pulverized coal airflow is heated by high-temperature flame coming from an adjacent upstream corner and is rapidly heated to the ignition temperature; when the boiler is operated at 40-50% of rated load, the average temperature of the hearth is lower, the flame temperature is reduced by 230-300 ℃, and after primary air pulverized coal airflow enters the hearth, high-temperature flame coming from an adjacent upstream corner is used for heating, so that the problems of slowing down the process of being heated to ignition temperature, unstable ignition and poor stable combustion performance can be caused. In the prior art, the four-corner tangential boiler has different minimum stable combustion loads of different coal types, when bituminous coal is used, the minimum stable combustion load is 40-45% of the rated load, when lean coal is used, the minimum stable combustion load is 45% of the rated load, and when anthracite coal is used, the minimum stable combustion load is 50% of the rated load. Along with the further reduction of load, furnace temperature reduces gradually, and the steady burning performance is progressively worsened, is less than after minimum steady burning load, appears flame-out accident easily. Therefore, the combustion stabilizing load of the four-corner tangential boiler in the prior art is high, and the peak regulation requirement that the combustion stabilizing load is 10-30% required for realizing carbon peak reaching and carbon neutralization cannot be met.
The embodiment of the invention provides a four-corner cut for self-stabilized combustion of low nitrogen oxideThe circular boiler system comprises an entrained-flow bed gasification furnace 1 and a four-corner tangential circular boiler 2, the entrained-flow bed gasification furnace 1 can gasify coal and a gasifying agent into crude synthesis gas, the crude synthesis gas generated by the entrained-flow bed gasification furnace 1 has high temperature which can reach 900-950 ℃, the ignition temperature is low and is 600-700 ℃, in addition, the gasification process is carried out under the anoxic condition, wherein O is 2 When the content of the raw synthesis gas and the primary air coal dust airflow sprayed out from the primary air nozzle 221 enter the boiler furnace 21 at the same time and are fully mixed, the oxygen content in the raw synthesis gas is rapidly increased by air brought in the primary air coal dust airflow, and the ignition point of the raw synthesis gas is 600-700 ℃ due to the fact that the temperature of the raw synthesis gas is 900-950 ℃, the oxygen content is increased, the raw synthesis gas can be rapidly ignited, the temperature is increased to 1300-1400 ℃, the burning raw synthesis gas heats the primary air coal dust airflow, the primary air coal dust airflow is ignited, and stable combustion is finally achieved. According to the four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides, provided by the embodiment of the invention, the primary air pulverized coal airflow is ignited by the crude synthesis gas, the primary air pulverized coal airflow is ignited by means of mixing of the crude synthesis gas and the primary air pulverized coal airflow, and is irrelevant to the temperature in a boiler hearth, so that the deep peak regulation requirement of 10-30% of rated load can be met when bituminous coal, lean coal and anthracite are selected as fire coal, and the self-stabilizing combustion performance is good.
The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention can reduce NO x (nitrogen oxide) emission concentration. The method comprises the following specific steps:
NO produced by burning of corner tangential boiler x Two main types, one is thermal NO x About 20-25%, and the other is fuel type NO x And accounts for about 75-80%. Fuel type NO x In addition, volatile NO can be classified x And NO of coke type x In which volatile NO is present x The amount of the coke-type NOx is about 60-80% of the fuel-type NOx, and the amount of the coke-type NOx is about 20-40% of the fuel-type NOx. Therefore, the key to controlling NOx emission levels from a corner-cut boiler combustion is to suppress fuel-type NO x . To influence the fuel type NO x Emission levels are mainly due to: excess air coefficient, furnace atmosphere and retention of primary air pulverized coal airflowTime. The excess air coefficient of the primary air pulverized coal airflow refers to the ratio of the primary air quantity to the theoretical air quantity required by combustion, the smaller the excess air coefficient of the primary air pulverized coal airflow is, the smaller the fuel type NO x The lower the production amount; the furnace atmosphere comprises an oxidizing atmosphere and a reducing atmosphere, wherein the HCN in the volatile N can form NCO after encountering oxygen, in the oxidizing atmosphere, the NCO can be further oxidized into NO, in the reducing atmosphere, the NCO can react to generate NH, the NH can be further oxidized into NO in the oxidizing atmosphere, and can also carry out reduction reaction with the generated NO in the reducing atmosphere to reduce the NO into N 2 (ii) a NH in volatile N 3 Can be further oxidized to NO in an oxidizing atmosphere, and can be reduced to N by a reduction reaction with the generated NO in a reducing atmosphere 2 (ii) a Therefore, the stronger the oxidizing atmosphere, the fuel type NO x The higher the emission concentration, the stronger the reducing atmosphere, the fuel type NO x The lower the emission concentration; accordingly, the longer the residence time in the oxidizing atmosphere, the fuel type NO x The higher the amount of formation, the longer the residence time of the reducing atmosphere, and the fuel type NO x The lower the production.
(1) The four-corner tangential boiler system capable of self-stably burning low nitrogen oxides provided by the embodiment of the invention can form strong reducing atmosphere in the center of the boiler furnace and inhibit NO x Generating:
in the prior art, the four-corner tangential boiler forms a reducing atmosphere mainly comprising coal incomplete combustion products CO at the center of a hearth to inhibit NO x But the concentration of CO is low and the reducing atmosphere is not strong. When the bituminous coal is set off, the volatile content of the bituminous coal is high, so that the ignition performance is good, and NO is contained x Low amount of generated NO at the furnace outlet x The discharge concentration can be controlled to be 600-900 mg/m 3 (in 6% O) 2 Reduced value); when burning lean coal, the poor coal has low volatile content, slightly poor fire-catching property and NO x High production of NO at the furnace outlet x The discharge concentration can be controlled to be 700-100 mg/m 3 (ii) a When burning anthracite, because of low volatile content, poor ignition performance and NO x Highest amount of NO produced at furnace outlet x Energy of discharged concentrationCan be controlled at 800-1100 mg/m 3 。
In the corner tangential boiler system for self-stabilized combustion of low nitrogen oxides provided by the embodiment of the invention, the entrained-flow bed gasifier 1 generates crude synthesis gas which contains a large amount of reducing gas, and because the diameter of the imaginary tangential circle corresponding to the synthesis gas outlet 31 is smaller than that of the imaginary tangential circle of the primary air nozzle 221, the unburned crude synthesis gas forms strong reducing atmosphere in the central area of the boiler furnace 21, so that the volatile N is inhibited from being converted into NO x Conversion is favorable for reducing NO into N by volatile N 2 (ii) a The crude synthesis gas is high-temperature and extremely flammable gas, the combustion speed is higher compared with that of coal dust in primary air coal dust airflow, oxygen is consumed rapidly due to ignition and combustion of the crude synthesis gas, so that local oxygen deficiency is higher, and coal dust is incompletely combusted to form a stronger reducing atmosphere.
(2) The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the invention can prolong the retention time of primary air pulverized coal airflow in reducing atmosphere and reduce NO x Generating:
in the prior art, a direct-current burner is adopted in a four-corner tangential boiler, and illustratively, when soft coal is used, the ignition distance is 0.7-1.2 m, when lean coal is used, the ignition distance is 1-1.4 m, and when anthracite coal is used, the ignition distance is 1.5-1.7 m; the four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention adopts the method that the crude synthesis gas generated by the entrained-flow bed gasifier 1 heats the primary air coal dust airflow sprayed out from the primary air nozzle, so that the primary air coal dust airflow is ignited and combusted at a position 0.4-0.5 m away from the primary air nozzle 221, the ignition distance is shortened by more than 0.2m, namely compared with the prior art, the primary air coal dust airflow in the embodiment of the invention stays more than 0.2m in the strong reducing atmosphere, and therefore, the four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides is beneficial to inhibiting volatile N from flowing to NO x Conversion is also facilitated to reduce NO to N by volatile N 2 While also inhibiting coke type NO x And (4) generating.
(3) The four-corner tangential boiler system capable of realizing self-stable combustion and low nitrogen oxide provided by the invention can reduce the excess air coefficient of the primary air pulverized coal airflow and inhibit NO x Generation of (1):
in the prior art, because a direct-current burner is adopted in a four-corner tangential boiler, in order to fully combust primary air pulverized coal airflow, a higher excess air coefficient and correspondingly NO of the primary air pulverized coal airflow need to be adopted x The emission concentration of (2) is also higher; the four-corner tangential boiler system capable of self-stably burning low nitrogen oxides provided by the embodiment of the invention adopts a mode of mixing the crude synthesis gas generated by the entrained-flow gasifier 1 and the primary air pulverized coal gas flow sprayed from the primary air nozzle 221, so that the excess air coefficient is reduced, and the suppression of the volatile component N to NO is facilitated x Conversion while also favoring inhibition of coke-type NO x Thereby making total fuel type NO x The product concentration is reduced.
The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention can improve the burnout performance of coal dust in primary air coal dust airflow and ash in crude synthesis gas. The method comprises the following specific steps:
(1) the four-corner tangential boiler system capable of self-stably burning low nitrogen oxides provided by the embodiment of the invention can reduce the ignition distance of primary air pulverized coal airflow, thereby improving burnout:
when the four-corner tangential boiler in the prior art runs at low load, the temperature of smoke in the boiler is 230-300 ℃ lower than that of the boiler at high load, the combustion is unstable and the burnout performance is poor, particularly in consideration of the running economy of the boiler, when hard-to-burn coal such as anthracite, lean coal and the like or the hard-to-burn coal is selected as fuel, the hard-to-burn coal has compact and stable lithofacies structure, small porosity and lower reactivity and is more difficult to burn out. For example, a four-corner tangential boiler in the prior art adopts a direct-current burner, and primary air pulverized coal airflow sprayed by the burner is heated by high-temperature flame from an upstream adjacent corner, so that the heating and the ignition are slow; the ignition distance is 0.7-1.2 m when bituminous coal is used, 1-1.4 m when lean coal is used, and 1.5-1.7 m when anthracite coal is used.
The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention adopts a mode that high-temperature crude synthesis gas generated by the entrained-flow bed gasification furnace 1 heats primary air coal dust airflow, so that the primary air coal dust airflow is ignited and combusted at a position 0.4-0.5 m away from the primary air nozzle 221, compared with the prior art, the ignition distance is reduced by more than 0.2m, the combustion process of the primary air coal dust airflow is carried out by more than 0.2m than the original combustion process, the combustion time of the primary air coal dust airflow is longer, and the combustion is facilitated.
(2) The four-corner tangential boiler system capable of realizing self-stable combustion and low nitrogen oxide provided by the embodiment of the invention can reduce the proportion of coal combustion, and is beneficial to improving burnout property:
the four-corner tangential boiler in the prior art does not comprise an entrained-flow bed gasification furnace 1, namely, the coal is combusted only by primary air pulverized coal airflow sprayed by a combustor, and the proportion of the coal is 100%. The four-corner tangential boiler system capable of self-stably burning low nitrogen oxides provided by the embodiment of the invention adopts a mixed burning mode of crude synthesis gas and primary air pulverized coal gas flow, wherein the crude synthesis gas belongs to extremely combustible gas, and the proportion of burning coal in the burning process is reduced, so that the burning is more favorable.
(3) The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention can improve the combustion rate of pulverized coal, and is beneficial to improving burnout property:
the faster the burning rate of the pulverized coal, the better the burnout performance. In the prior art, primary air pulverized coal airflow ejected by a direct-current burner of a boiler with four tangential corners is heated by high-temperature flame coming from an adjacent upstream corner, and the primary air pulverized coal airflow is heated to be above the ignition temperature and then is ignited; the four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxide provided by the embodiment of the invention adopts the entrained-flow bed gasification furnace 1 to generate the crude synthesis gas, and heats the primary air pulverized coal airflow by means of the high-temperature crude synthesis gas, and because the crude synthesis gas outlet 31 and the primary air nozzles 221 are both positioned at the four corners of the boiler furnace 21, the crude synthesis gas can be quickly mixed with the primary air pulverized coal airflow to heat the primary air pulverized coal airflow and quickly catch fire. The combustion rate of the pulverized coal is in an exponential power relation with the temperature, the higher the temperature is, the higher the combustion rate of the pulverized coal is, for example, when the temperature of the pulverized coal is increased from 1000 ℃ to 1100 ℃, the combustion rate of the pulverized coal is increased by about 3 times. Therefore, the four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention can improve burnout performance by increasing the combustion rate of pulverized coal.
(4) The four-corner tangential boiler system capable of self-stably burning low nitrogen oxides provided by the embodiment of the invention can strengthen the falling of the burnt ash shell of the coal dust particles, and improve the burnout property of the coal dust in the primary air coal dust airflow:
the ash of the raw synthesis gas generated by the entrained-flow gasifier 1 in the self-stabilized low-nitrogen-oxide-content corner-cut-circle boiler system provided by the embodiment of the invention contains solid particles, and when the raw synthesis gas and the primary air pulverized coal gas flow are violently mixed and combusted, the ash solid particles carried in the raw synthesis gas can collide with an ash shell generated after the pulverized coal particles in the primary air pulverized coal gas flow are combusted to fall off, so that the combustion in the pulverized coal particles is facilitated, and the burnout performance is improved.
(5) The self-stabilized combustion low-nitrogen oxide four-corner tangential boiler system provided by the embodiment of the invention has the advantages that the primary air pulverized coal airflow is closer to the wall surface and stays in the boiler for a longer time, and the burnout of pulverized coal in the primary air pulverized coal airflow is improved:
the diameter of the imaginary tangent circle corresponding to the synthesis gas outlet 31 in the self-stabilized low-nitrogen oxide four-corner tangent circle boiler system provided by the embodiment of the invention is smaller than that of the imaginary tangent circle corresponding to the primary air nozzle 221, so that primary air pulverized coal airflow sprayed by the primary air nozzle 221 is closer to the wall surface, a weak reducing or weak oxidizing region is formed in the region close to the wall surface, the oxygen content is higher than that of the central region of the boiler furnace 21, the combustion of pulverized coal is facilitated, the burnout performance of the pulverized coal is improved, and the slag bonding of the wall surface is prevented; after the raw synthesis gas is sprayed into the boiler furnace 21 and combusted, primary air pulverized coal airflow flame sprayed from the upstream primary air nozzle 221 can be impacted, airflow mixing is enhanced, unburned pulverized coal particles are favorably ignited, and burnout performance is improved.
In addition, the diameter of the virtual tangent circle corresponding to the primary air nozzle 221 is larger, so that the length of the trajectory of the pulverized coal in the primary air pulverized coal airflow rotating and rising in the boiler furnace 21 is long, the time of staying in the boiler is longer, and the burnout property can also be improved.
(7) The four-corner tangential boiler system capable of self-stably burning low nitrogen oxides provided by the embodiment of the invention can enhance the falling of the burnt ash shell of the ash particles in the crude synthesis gas by improving the oxygen supply amount, and improve the burnout property of the ash in the crude synthesis gas:
the ash in the crude synthesis gas produced by the traditional gasification process has the combustible content of 40-50%, is difficult to be recycled, and causes the waste of coal resources, and the ash is mainly piled up or buried, so that the serious environmental pollution and the waste of land resources are caused.
In the traditional gasification process, in order to cause explosion caused by combustion of the raw synthesis gas due to overhigh wall surface oxygen content, the gasification process needs to be carried out under an anoxic condition, and the ratio of the oxygen supply amount in the traditional gasification furnace to the oxygen amount required by complete combustion of coal is 0.5-0.6, so that the coal is not fully combusted in the gasification furnace, and the combustible content in fly ash can reach 40-50%.
According to the corner tangential boiler system with the self-stable combustion and the low nitrogen oxide, provided by the embodiment of the invention, the crude synthesis gas generated by the entrained-flow bed gasification furnace 1 is introduced into the corner tangential boiler 2 to be combusted together with the primary air pulverized coal airflow sprayed out from the primary air nozzle 221, the ratio of the oxygen supply amount in the corner tangential boiler 2 to the oxygen amount required by complete combustion of coal is 1.1-1.2, which is far higher than that of the traditional gasification process, due to sufficient oxygen supply amount, the combustible of fly ash in the crude synthesis gas introduced into the corner tangential boiler 2 can be reduced from 40-50% to 4-5%, the reduction range is 87.5-92%, and the burnout property of the crude synthesis gas is obviously improved.
In addition, the raw synthesis gas generated by the entrained-flow gasifier 1 in the self-stabilized low-nitrogen-oxide-content boiler system provided by the embodiment of the invention contains solid particles, and when the raw synthesis gas and the primary air pulverized coal gas flow are mixed vigorously and combusted, the ash solid particles carried in the raw synthesis gas can collide with an ash shell generated after the combustion of the pulverized coal particles in the primary air pulverized coal gas flow to fall off, so that the combustion of the interior of the ash particles in the raw synthesis gas is facilitated, and the burnout property of the raw synthesis gas is improved.
As shown in fig. 3 and 4, the syngas outlet 31 is laterally provided with a rectangular protrusion 311, the primary air nozzle 221 is laterally provided with a rectangular recess 2211, and the syngas outlet 31 and the primary air nozzle 221 are engaged with each other through the rectangular protrusion 311 and the rectangular recess 2211.
Specifically, an included angle between the syngas outlet 31 and a central line of the primary air nozzle 221 is α, the number of the rectangular recesses 2211 in the primary air nozzle 221 is n, the depth of the rectangular recess 2211 is h, the thickness of the rectangular recess 2211 is b, the rectangular recesses 2211 are uniformly distributed on the primary air nozzle 221, and the area of the syngas outlet 31 is a 1 The area of the primary air nozzle 221 is A 2 The area of the rectangular recess 2211 is A 3 (ii) a When the burning coal is bituminous coal, i.e. V daf When more than 20%, alpha is 0-6 deg., n is 0, 1 or 2, b is 20-30 mm, h is 1-1.5 b, A 1 ＝0.35～0.5A 2 ，A 3 ＝0～5％A 2 (ii) a When the burning coal is lean coal, namely V is more than or equal to 10% daf Not more than 20%, alpha is 5-9 deg., n is 2 or 3, b is 25-35 mm, h is 1.5-2.5 b, A 1 ＝0.4～0.5A 2 ，A 3 ＝3～15％A 2 (ii) a When the burning coal is anthracite, i.e. V daf <10% of alpha is 5-12 deg., n is 3 or 4, b is 25-35 mm, h is 2.5-4 b, A 1 ＝0.4～0.5A 2 ，A 3 ＝10～22％A 2 。
The angle between the syngas outlet 31 and the center line of the primary air nozzle 221 is α, and when the position of the primary air nozzle 221 is unchanged, the larger α is, the smaller the diameter of the imaginary circle of tangency corresponding to the syngas outlet 31 is, the more raw syngas is unburned in the center of the boiler furnace 21, and the stronger the reducing atmosphere is. When the burning coal is bituminous coal, i.e. V daf >When the concentration is 20 percent, alpha is 0-6 degrees, so that a strong enough reducing atmosphere can be formed in the center of the hearth, and NO is added x The discharge concentration can be controlled to be 300-500 mg/m 3 (6％O 2 Reduced value); when the burning coal is lean coal, namely V is more than or equal to 10% daf When the content is less than or equal to 20 percent, alpha is 5-9 degrees and NO is selected x The discharge concentration can be controlled to be 300-500 mg/m 3 (6％O 2 Reduced value); when the burning coal is anthracite, i.e. V daf <When 10 percent, alpha is 5-12 degrees, enough strong reducing atmosphere can be formed in the center of the boiler furnace, and NO is added x The discharge concentration can be controlled to be 300-500 mg/m 3 (6％O 2 Reduced value). Under the strong reducing atmosphere, the method is favorable for inhibiting volatile N from converting to NO x Conversion and is beneficial to reducing NO into N by volatile N 2 (ii) a Meanwhile, the volatile matter consumes a large amount of oxygen, which is favorable for inhibiting coke type NO x Thereby generating total fuel type NO x The product concentration is reduced.
The rectangular recess 2211 of the primary air nozzle 221 is beneficial to enhancing the mixing of primary air pulverized coal airflow and crude synthesis gas, and obviously, the larger the number n of the recesses is, the larger A is 3 Occupy A 2 The larger the proportion is, the better the mixing effect is, and the stronger the ignition capability of the burning crude synthesis gas to the primary air pulverized coal flow is. When the burning coal is bituminous coal, i.e. V daf >When 20%, n is 0, 1 or 2, b is 20-30 mm, h is 1-1.5 b, A 3 ＝0～5％A 2 The ignition requirement can be met, and the ignition distance of the primary air pulverized coal airflow is 0.4-0.5 m; when the burning coal is lean coal, namely V is more than or equal to 10% daf When the content is less than or equal to 20 percent, n is 2 or 3, b is 25-35 mm, h is 1.5-2.5 b, A 3 ＝3～15％A 2 The ignition requirement is met, and the ignition distance of the primary air pulverized coal airflow is 0.4-0.5 m; when the burning coal is anthracite, i.e. V daf <When 10%, n is 3 or 4, b is 25-35 mm, h is 2.5-4 b, A 3 ＝10～22％A 2 The mixing effect is best, the ignition requirement of the anthracite coal dust can be met, and the ignition distance of primary air coal dust airflow is 0.4-0.5 m. Finally, stable combustion is realized.
The four-corner tangential boiler system capable of self-stably burning low nitrogen oxides further comprises a radiation waste pot 4 and a slag pool 5, the entrained flow gasifier 1 is sequentially connected with the radiation waste pot 4 and the slag pool 5 from top to bottom, and the radiation waste pot 4 is communicated with the four-corner tangential boiler 2 through the synthesis gas channel 3. The temperature of the crude synthesis gas generated in the entrained flow gasifier 1 can be properly reduced in the radiation waste boiler 4, the slag pool 5 is used for containing slag generated in the crude synthesis process, and the radiation waste boiler 4 is communicated with the four-corner tangential boiler 2 through the synthesis gas channel 3, so that the crude synthesis gas after being properly cooled can be introduced into the four-corner tangential boiler 2.
Wherein the height of the entrained-flow gasifier 1 is H 1 The height of the radiation waste pot 4 is H 2 And H is 1 ＝0.2～0.35H 2 . The temperature of the radiation waste boiler can be controlled to be about 950 ℃ by controlling the heights of the entrained-flow bed gasification furnace 1 and the radiation waste boiler 4.
Illustratively, the height of the radiation waste heat boiler 4 is 5-7 m.
In addition, the burner nozzle 22 further comprises a secondary air nozzle 222 for burning coal V daf When the air flow rate is more than or equal to 10%, the primary air nozzles 221 and the secondary air nozzles 222 are arranged in an equal air distribution mode, and the primary air nozzles 221 and the secondary air nozzles 222 are arranged at intervals; when burning coal type V daf When the air flow rate is less than 10%, primary air is intensively arranged, and the primary air nozzles 221 are intensively arranged together.
Illustratively, when burning coal type V daf When the air flow rate is more than or equal to 10 percent, the primary air nozzles 221 and the secondary air nozzles 222 adopt a II-I-II arrangement mode; when burning coal type V daf When the concentration is less than 10%, adopting a II-I-II arrangement mode; wherein, I represents a primary air nozzle 221, II represents a secondary air nozzle 222, the primary air nozzle 221 ejects primary air pulverized coal airflow, namely mixed airflow of pulverized coal and air, and the secondary air nozzle 222 ejects air.
It should be understood that, when the burner nozzle 22 includes a plurality of layers of primary air nozzles 221, the syngas outlet 31 is correspondingly disposed in a plurality of layers, and the syngas channel 3 is connected to the plurality of layers of syngas outlets 31, so that the raw syngas generated in the entrained-flow gasifier 1 is uniformly sprayed through the plurality of syngas outlets 31.
The four-corner tangential boiler 2 is distributed with water-cooled walls around and is provided with a convection heating surface in the 2 flues of the four-corner tangential boiler. The water-cooled walls are steel pipes arranged around the four-corner tangential boiler 2, the convection heating surfaces are steel pipes arranged in a flue of the four-corner tangential boiler 2, and water circulates inside the steel pipes.
As shown in figure 2, the entrained-flow gasifier in the prior art comprises a gasification chamber 6, a chilling chamber 7 and a slag pool, wherein the chilling chamber 7 is internally provided with a chilling water pipe 71 and a chilling ring 711, after high-temperature crude synthesis gas generated by the gasification chamber 6 enters the chilling chamber 7, chilling water at 180-200 ℃ is ejected from the chilling ring 711 and mixed into the crude synthesis gas, so that the temperature of the crude synthesis gas is reduced to 200-220 ℃, then the crude synthesis gas and the vaporized chilling steam enter a subsequent purification process through a synthesis gas channel, and are further cooled to about 130 ℃ in the subsequent purification process.
That is to say, in the gasification process in the prior art, the high-temperature crude synthesis gas is subjected to chilling and subsequent purification processes to obtain a mixture working medium with the temperature of about 100 ℃ and the pressure of 0.7-0.8 MPa, the quality of the working medium is low, and heat energy in the high-temperature crude synthesis gas is not utilized, so that heat energy generated in the gasification furnace is lost.
The four-corner tangential boiler system capable of self-stabilizing combustion of low nitrogen oxides provided by the embodiment of the invention removes the chilling chamber and does not adopt a chilling mode to treat the crude synthesis gas. And introducing the high-temperature crude synthesis gas into a four-corner tangential boiler 2 to be coupled with primary air pulverized coal gas flow for combustion, and raising the temperature to 1300-1400 ℃. On the one hand, high temperature flame heats through the water to the water-cooling wall to radiation heat transfer form and water-cooling wall carry out heat exchange, make the water in the water-cooling wall turn into steam output, and on the other hand, the water in the high temperature flue gas heating convection heat transfer face carries out heat exchange with the convection heat transfer face with the convection heat transfer form, makes the water in the convection heat transfer face turn into steam output equally, and the final working medium that obtains is high temperature high pressure steam, and steam quality is high, easy to use.
Another embodiment of the present invention provides a combustion method of the above four-corner tangential boiler system for self-stabilized combustion of low nitrogen oxides, wherein a coarse synthesis gas is generated through the entrained-flow gasifier 1, the coarse synthesis gas is injected into the four-corner tangential boiler 2 through the synthesis gas channel 3, a primary air pulverized coal gas flow is injected into the four-corner tangential boiler 2 through the primary air nozzle 221, and the coarse synthesis gas and the primary air pulverized coal gas flow are simultaneously injected into the four-corner tangential boiler 2.
Wherein the raw synthesis gas comprises CO and H 2 、O 2 、CO 2 、H 2 O and ash, wherein, in volume fraction, the CO and the H 2 85-88% of the total weight of the composition, and O 2 The ratio is less than 0.5%, the content of combustible substances in ash is 45-0-50%, and the mass ratio of the crude synthesis gas to the primary air pulverized coal airflow is 0.4-0.45: 1.
The ignition temperature of the crude synthesis gas is 600-700 ℃, and CO and H are 2 Belongs to reducing gas, can form reducing atmosphere in a boiler hearth, is extremely easy to burn, and is beneficial to reducing NO x Discharging and improving burnout.
The mass ratio of the crude synthesis gas to the primary air pulverized coal airflow is 0.4-0.45: 1, when the two are mixed, the excess air index of the primary air pulverized coal airflow is reduced to 0.25-0.3, and reduction of the excess air coefficient is beneficial to inhibiting volatile N from being converted into NO x Conversion and inhibition of coke-type NO x And (4) generating. In addition, the fire coal proportion can be reduced, and the burnout property can be improved.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are examples of experimental procedures not specified under specific conditions, generally according to the conditions recommended by the manufacturer.
Examples
The gas production amount is 80000Nm 3 The self-stable combustion low-nitrogen oxide four-corner tangential boiler system comprises an entrained-flow bed gasifier 1 and a 600Mwe four-corner tangential boiler 2, coal for combustion is lean coal, the structure of the system is shown in figures 1-4, the system comprises the entrained-flow bed gasifier 1, a radiation waste boiler 4, a slag bath 5 and the four-corner tangential boiler 2, the entrained-flow bed gasifier 1, the radiation waste boiler 4 and the slag bath 5 are sequentially connected up and down, the four-corner tangential boiler 2 comprises a boiler furnace 21 and a burner nozzle 22, and the burner nozzle 22 comprises a primary air nozzle 221 and a secondary air nozzle 222; wherein, radiation is useless pot 4 and is passed through synthetic gas passageway 3 and four corners tangential boiler 2 intercommunication, and synthetic gas passageway 3 is connected with a plurality of synthetic gas export 31 of distributing on boiler furnace 21 four angles, and a plurality of synthetic gas exports 31 and a plurality of once wind spout 221 distribute on boiler furnace 21 four angles, and the central line of synthetic gas export 31 and once wind spout 221 respectively with pot 21 four anglesOne or more imaginary tangent circles in the furnace hearth 21 are tangent, wherein the diameter of the syngas outlet 31 corresponding to the imaginary tangent circle is smaller than the diameter of the primary air nozzle 221 corresponding to the imaginary tangent circle.
The side of the synthesis gas outlet 31 is provided with a rectangular protrusion 311, the side of the primary air nozzle 221 is provided with a rectangular recess 2211, and the synthesis gas outlet 31 and the primary air nozzle 221 are mutually embedded through the rectangular protrusion 311 and the rectangular recess 2211. The included angle between the central lines of the synthesis gas outlet 31 and the primary air nozzle 221 is alpha, the number of the rectangular recesses 2211 in the primary air nozzle 221 is n, the depth of the rectangular recesses 2211 is h, the thickness of the rectangular recesses 2211 is b, the rectangular recesses 2211 are uniformly distributed on the primary air nozzle 221, and the area of the synthesis gas outlet 31 is A 1 The area of the primary air nozzle 221 is A 2 The rectangular recess 2211 has an area A 3 α is 5 to 9 °, n is 2 or 3, b is 25 to 35mm, h is 1.5 to 2.5b, A 1 ＝0.4～0.5A 2 ，A 3 ＝3～15％A 2 。
Wherein the height of the entrained-flow gasifier 1 is H 1 The height of the radiation waste pot 4 is H 2 ，H 1 ＝0.2～0.35H 2 . The primary air nozzles 221 and the secondary air nozzles 222 are arranged in an equal air distribution type of II-I-II, and water cooling walls are distributed around the four-corner tangential boiler 2.
The entrained-flow bed gasification furnace 1 generates crude synthesis gas, the crude synthesis gas is directly sprayed into the boiler furnace 21 through the synthesis gas channel 3, and the crude synthesis gas and primary air coal dust airflow in the primary air nozzle 221 are simultaneously sprayed into the boiler furnace 21 to enter. Wherein the raw synthesis gas comprises CO and H 2 、O 2 、CO 2 、H 2 O and ash, wherein, in volume fraction, CO and H 2 85-88% of O 2 The ratio is less than 0.5%, the content of combustible substances in ash is 45-50%, and the mass ratio of the crude synthesis gas to the primary air pulverized coal airflow is 0.4-0.45: 1.
The combustible content in fly ash generated by the corner tangential boiler 2 is 4%, the combustible content in ash in the crude synthesis gas is 4%, and NO of the corner tangential boiler x The discharge concentration is 220mg/m 3 (6％O 2 Reduced value), minimum no oil input and stable combustion loadThe temperature is reduced to 30 percent, and no accident occurs in two years of operation.
In the prior art, in the traditional 600Mwe four-corner tangential boiler, the coal used for combustion is also lean coal, the combustible content in the generated fly ash reaches 12 percent, and NO is not added x The discharge amount is about 980mg/m 3 (6％O 2 A reduced value), the minimum fuel-injection-free stable-combustion load is 45%, and two fire-extinguishing accidents occur in a low-load operation period within one year of operation, so that the furnace needs to be stopped and re-ignited, and great economic loss is caused.
The gas production in the prior art is 80000Nm 3 The/h gasification furnace adopts a chilling mode to treat the crude synthesis gas, the combustible content in the crude synthesis gas is about 45 percent, about 3.1 ten thousand tons of coal are not fully utilized in one year, and the temperature of the crude synthesis gas is rapidly reduced to 215 ℃ after being chilled, so that heat energy waste is caused, and the heat energy loss is large.
Compared with the combustible content in the fly ash in the four-corner tangential boiler in the prior art, the four-corner tangential boiler system and the combustion method for self-stabilized combustion of low nitrogen oxide provided by the embodiment of the invention can reduce the combustible content by about 67%, which is equivalent to save 37500 tons of standard coal in one year, the combustible content in the fly ash of the crude synthesis gas can reduce by 91% compared with the prior art gasification furnace, which is equivalent to save 28500 tons of fire coal in one year, and NO x The emission concentration is obviously reduced, the lowest stable combustion load rate is reduced, no accident happens when the fuel is operated for two years, the fuel has good self-stable combustion performance, and great economic benefit is generated.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the disclosure, and these changes and modifications are intended to fall within the scope of the invention.
Claims (10)
1. The utility model provides a self-stabilizing low nitrogen oxide's corner tangential boiler system, characterized by, include entrained-flow gasifier (1) and corner tangential boiler (2), the corner tangential boiler (2) includes combustor spout (22), the combustor spout (22) includes primary air spout (221); the entrained-flow bed gasification furnace (1) is communicated with the four-corner tangential boiler (2) through a synthesis gas channel (3), synthesis gas outlets (31) and the primary air nozzles (221) are distributed on four corners of the four-corner tangential boiler (2), the synthesis gas channel (3) is connected with the synthesis gas outlets (31), and the synthesis gas outlets (31) and the primary air nozzles (221) are the same in height; the central lines of the synthetic gas outlet (31) and the primary air nozzle (221) are respectively tangent to one or more imaginary tangent circles in the four-corner tangential boiler (2), and the diameter of the synthetic gas outlet (31) corresponding to the imaginary tangent circle is smaller than that of the primary air nozzle (221) corresponding to the imaginary tangent circle.
2. The corner-cut boiler system with self-stabilized combustion and low NOx of claim 1, wherein the side of the syngas outlet (31) is provided with a rectangular protrusion (311), the side of the primary air nozzle (221) is provided with a rectangular recess (2211), and the syngas outlet (31) and the primary air nozzle (221) are embedded with each other through the rectangular protrusion (311) and the rectangular recess (2211).
3. The corner-cut boiler system with self-stabilized combustion and low NOx of claim 2, characterized in that the included angle between the syngas outlet (31) and the center line of the primary air nozzle (221) is α, the number of the rectangular recesses (2211) in the primary air nozzle (221) is n, the depth of the rectangular recesses (2211) is h, the thickness of the rectangular recesses (2211) is b, and the rectangular recesses (2211) are evenly distributed on the primary air nozzle (221), the area of the syngas outlet (31) is A 1 The area of the primary air nozzle (221) is A 2 The area of the rectangular recess (2211) is A 3 (ii) a When burning coal type V daf When the alpha is more than 20 percent, the alpha is 0-6 degrees, the n is 0, 1 or 2, the b is 20-30 mm, the h is 1-1.5 b, A 1 ＝0.35～0.5A 2 ，A 3 ＝0～5％A 2 (ii) a When burning coal, V is less than or equal to 10% daf Not more than 20%, alpha is 5-9 deg., n is 2 or 3, b is 25-35 mm, h is 1.5-2.5 b, A 1 ＝0.4～0.5A 2 ，A 3 ＝3～15％A 2 (ii) a When burning coal type V daf <10% of alpha is 5-12 deg., n is 3 or 4, b is 25-35 mm, h is 2.5-4 b, A 1 ＝0.4～0.5A 2 ，A 3 ＝10～22％A 2 。
4. The self-stable combustion low nitrogen oxide tetragonal tangential boiler system according to claim 1, further comprising a radiation waste pot (4) and a slag bath (5), wherein the entrained flow gasifier (1) is sequentially connected with the radiation waste pot (4) and the slag bath (5) from top to bottom, and the radiation waste pot (4) is communicated with the tetragonal tangential boiler (2) through the syngas channel (3).
5. The corner-cut boiler system for self-stabilized combustion of low NOx according to claim 4, wherein the height of the entrained-flow gasifier (1) is H 1 The height of the radiation waste pot (4) is H 2 And H is 1 ＝0.2～0.35H 2 。
6. The corner-cut boiler system with self-stabilized combustion and low NOx of claim 1, wherein the burner ports (22) further comprise overfire air ports (222) for V-shaped combustion of coal daf When the air flow rate is more than or equal to 10%, the primary air nozzles (221) and the secondary air nozzles (222) are arranged in an equal air distribution mode, and the primary air nozzles (221) and the secondary air nozzles (222) are arranged at intervals; when burning coal type V daf If the air flow rate is less than 10%, primary air is intensively arranged, and the primary air nozzles (221) are intensively arranged together.
7. The self-stabilized low NOx corner-cut boiler system according to claim 1, wherein water-cooled walls are distributed around the corner-cut boiler (2).
8. The combustion method of the self-stable combustion low-nitrogen oxide tetragonal tangential boiler system according to any one of claims 1-7, characterized in that raw synthesis gas is generated through an entrained flow gasifier (1), the raw synthesis gas is injected into the tetragonal tangential boiler (2) through a synthesis gas channel (3), primary air pulverized coal gas is injected into the tetragonal tangential boiler (2) through a primary air nozzle (221), and the raw synthesis gas and the primary air pulverized coal gas are simultaneously injected into the tetragonal tangential boiler (2).
9. The combustion method of claim 8, wherein the raw syngas comprises CO, H 2 、O 2 、CO 2 、H 2 O and ash, wherein the CO and the H are in volume fraction 2 85-88% of the total weight of the composition, and O 2 The ratio is less than 0.5%.
10. The combustion method according to claim 8, wherein the mass ratio of the raw synthesis gas to the primary air pulverized coal stream is 0.4-0.45: 1.
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