CN113654079A - Combustion method for effectively reducing slagging and high-temperature corrosion of boiler hearth - Google Patents
Combustion method for effectively reducing slagging and high-temperature corrosion of boiler hearth Download PDFInfo
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- CN113654079A CN113654079A CN202110997273.8A CN202110997273A CN113654079A CN 113654079 A CN113654079 A CN 113654079A CN 202110997273 A CN202110997273 A CN 202110997273A CN 113654079 A CN113654079 A CN 113654079A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
- F23K3/02—Pneumatic feeding arrangements, i.e. by air blast
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L1/00—Passages or apertures for delivering primary air for combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel
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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
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Abstract
The invention provides a combustion method for effectively reducing slagging and high-temperature corrosion of a boiler hearth, which comprises the following steps: s1, dividing a boiler furnace into a main combustion area and a burnout area from bottom to top; s2, injecting two coal powder air flows with large concentration difference into the hearth; s3, spraying primary air and over-fire air through a hearth nozzle; and S4, spraying a primary amino reducing agent and a secondary amino reducing agent into the main combustion zone and the burnout zone respectively. The combustion method for effectively reducing the slagging and the high-temperature corrosion of the boiler furnace provided by the invention solves the problems that the prior art obtains a better low NOx emission effect, but the pulverized coal is combusted in a reducing atmosphere after the whole air quantity of a main combustion zone is reduced, the melting point of the ash of the coal ash is reduced, a combustor adopts a centralized arrangement mode, the combustion temperature of the pulverized coal is higher, the slagging condition of the water-cooled wall of the boiler furnace is worsened, and the high-temperature corrosion of the water-cooled wall is aggravated.
Description
Technical Field
The invention belongs to the technical field of electric power energy, and particularly relates to a combustion method for effectively reducing slagging and high-temperature corrosion of a boiler hearth.
Background
The electric power energy is mainly thermal power generation of coal, most of power coal in China is low-grade inferior coal, slagging of a hearth in the combustion process of a boiler is a problem which puzzles the operation of a power plant for a long time, at present, a burner is arranged in a centralized mode, the combustion temperature of pulverized coal is high, the slagging condition of a water-cooled wall of a hearth of the boiler is worsened, and high-temperature corrosion of the water-cooled wall is aggravated.
The existing technology obtains a good low NOx emission effect, but after the whole air quantity of a main combustion area is reduced, pulverized coal combustion is carried out under a reducing atmosphere, the melting point of coal ash is reduced, a burner adopts a centralized arrangement mode, the pulverized coal combustion temperature is higher, the slagging condition of a water cooling wall of a boiler hearth is worsened, and the high-temperature corrosion of the water cooling wall is aggravated.
Disclosure of Invention
In order to solve the technical problems, the invention provides a combustion method capable of effectively reducing slagging and high-temperature corrosion in a combustion area.
The invention is realized by adopting the following technical scheme:
a combustion method for effectively reducing slagging and high-temperature corrosion of a boiler furnace comprises the following steps:
s1, dividing a boiler furnace into a main combustion area and a burnout area from bottom to top;
s2, injecting two coal powder air flows with large concentration difference into the hearth;
s3, spraying primary air and over-fire air through a hearth nozzle;
and S4, spraying a primary amino reducing agent and a secondary amino reducing agent into the main combustion zone and the burnout zone respectively.
The invention has the further improvement that the main burning zone and the burnout zone in the S1 are limited by the injection port of the burnout air, and the temperature in the furnace chamber of the boiler is 1000-1300 ℃.
The further improvement of the invention is that the oxygen content in the hearth of S1 is 3.5-4.5 wt%, the excess air coefficient of the main combustion zone is 0.95, and the excess air coefficient of the burnout zone is 1.16-1.17.
The invention is further improved in that the dense-phase coal dust airflow in the S2 is emitted to the fire-facing side of the hearth, and the light-phase coal dust airflow is emitted to the back fire side of the hearth.
The invention is further improved in that the reference wind pressure of the primary wind in the S3 is 9.0-9.5 KPa, and the wind speed of the primary wind is 30-38 m/S.
The invention further improves that the primary air and the over-fire air in the S3 adopt horizontal thick and thin nozzles, and the air flow is parallel to the central axis of the hearth.
The further improvement of the invention is that the molar ratio of NH3 generated by the amino reducing agent injected into the main combustion zone in S4 to nitrogen oxides in flue gas of the main combustion zone is 0.5-1.1: 1, and the molar ratio of NH3 generated by the amino reducing agent injected into the burnout zone to nitrogen oxides in flue gas of the burnout zone is 0.6-1.5: 1.
In a further improvement of the invention, in the step S4, the primary combustion zone is injected with a primary amino reducing agent, and the burnout zone is injected with a secondary amino reducing agent.
The invention further improves that the solid particles of the primary amino reducing agent in S4 are ammonium bicarbonate particles, and the particle size is less than 1 mm.
The further improvement of the invention is that the secondary amino reducing agent sprayed into the burnout zone in S4 is an ammonia water solution with the mass concentration of 5-20% or an ammonium bicarbonate solution.
Compared with the prior art, the combustion method for effectively reducing the slagging and the high-temperature corrosion of the boiler furnace provided by the invention has the following beneficial effects:
the invention divides the boiler furnace from bottom to top into a main burning area and a burnout area, the main burning area and the burnout area in S1 are limited by the injection port of the burnout air, when the temperature in the furnace of the boiler is 1000-1300 ℃, the temperature in the furnace of the boiler is set to 1000-1300 ℃, the coking degree in the furnace is minimized, the oxygen content in the furnace in S1 is 3.5-4.5 wt%, the excess air coefficient of the main burning area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, the generation of NOx can be effectively reduced by finding the proper oxygen content in the furnace to be 3.5-4.5 wt%, so that the smoke temperature at the outlet of the furnace is kept in a lower range, the excess air coefficient of the main burning area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, two streams of coal dust air with larger concentration difference are injected into the furnace, the dense phase air stream in S2 is shot to the fire side, the light phase air stream is shot to the back of the furnace, the classification of primary air in the horizontal direction is realized by arranging dense-phase pulverized coal airflow to irradiate the fire side of a hearth and light-phase pulverized coal airflow to irradiate the fire side of the hearth, so that the structure of wind-coated powder is formed, slag bonding and high-temperature corrosion of a water-cooled wall can be effectively avoided, primary air and over-fire air are sprayed through a hearth nozzle, the reference wind pressure of the primary air in S3 is 9.0-9.5 KPa, the wind speed of the primary air is 30-38 m/S, the wind speed and the wind volume under the condition that the primary air pipe carries pulverized coal are measured to carry out pressure leveling, the wind pressure of the primary air is controlled to be 9.0-9.5 KPa as the reference wind pressure to carry out adjustment in normal operation, a curve that the wind speed in the primary air pipe changes along with the output of the pulverized coal preparation is drawn, the smoke temperature at the outlet of the hearth is controlled by adjusting the wind speed of the primary air to be 30-38 m/S, in the adjustment of actual operation, the proper oxygen content in the hearth is found to be 3.5-4.5 wt% through wind distribution adjustment, so as to keep the smoke temperature at the outlet of the hearth in a lower range, a horizontal thick and thin nozzle is adopted for primary air and overfire air in S3, the air flow is parallel to the central axis of the hearth, the air flow direction of the sprayed primary air coal dust is parallel to the central axis of a burner, the secondary air flow is favorable for dragging the coal dust layer to prevent the coal dust from falling into a bottom ash bucket, the carbon content of bottom slag is effectively reduced, the secondary air flow and the primary coal dust air flow are ensured to be mixed in time, the oil-free stable combustion capability and the coal dust combustion efficiency of a unit in a low-load operation stage are improved, a primary amino reducing agent and a secondary amino reducing agent are respectively sprayed into a main combustion zone and an overfire zone, the molar ratio of NH3 generated by the amino reducing agent sprayed into the main combustion zone in S4 to nitrogen oxides in the flue gas of the main combustion zone is 0.5-1.1: 1, the molar ratio of NH3 generated by the amino reducing agent sprayed into the overfire zone to nitrogen oxides in the overfire flue gas of the overfire zone is 0.6-1.5: 1, compared with the conventional air staged combustion technology, the method has the advantages that the main combustion area adopts weak reducing atmosphere, slag bonding is effectively avoided when brown coal is combusted, the primary amino reducing agent is sprayed into the main combustion area in S4, the secondary amino reducing agent is sprayed into the burnout area, the solid particles of the primary amino reducing agent in S4 are ammonium bicarbonate particles with the particle size smaller than 1mm, the secondary amino reducing agent is sprayed into the burnout area in S4 and is ammonia water solution with the mass concentration of 5-20% or ammonium bicarbonate solution, the amino reducing agent is sprayed into the main combustion area, NOx in flue gas is removed by utilizing the reducing component generated during combustion in coal powder reducing atmosphere and NH generated by decomposition of the amino reducing agent in a synergistic manner, the NOx concentration of the flue gas at the outlet of the main combustion area is reduced by the weak reducing atmosphere in the main combustion area and the feeding of the amino reducing agent, the method can effectively prevent slag bonding and high-temperature corrosion of a water cooled wall of a boiler at the early stage of ensuring low pollutant emission of the boiler, furnace grouped arrangement is favorable to reducing the heat load of the combustion area of the boiler, reduce the smoke temperature level of the combustion area of the boiler, can effectively reduce the slagging scorification of the combustion area and generate high temperature, the problem of the prior art that better low NOx emission effect is obtained is solved, but after the whole air quantity of the main combustion area is reduced, pulverized coal combustion is carried out under reducing atmosphere, the melting point of coal ash is reduced, the combustor adopts a centralized arrangement mode, the pulverized coal combustion temperature is higher, the slagging condition of the water-cooled wall of the boiler furnace is worsened, and the problem of the aggravation of the high-temperature corrosion of the water-cooled wall is solved.
Drawings
FIG. 1 is a schematic diagram of the operation of the combustion method for effectively reducing the slagging and the high-temperature corrosion of the boiler furnace provided by the invention.
Detailed Description
The invention is further described with reference to the following figures and embodiments.
Please refer to the working schematic diagram of the combustion method for effectively reducing the slag formation and the high temperature corrosion of the boiler furnace provided by the present invention. The combustion method for effectively reducing slagging and high-temperature corrosion of the boiler furnace comprises the following steps of S1, dividing the boiler furnace into a main combustion area and an burnout area from bottom to top; s2, injecting two coal powder air flows with large concentration difference into the hearth; s3, spraying primary air and over-fire air through a hearth nozzle; and S4, spraying a primary amino reducing agent and a secondary amino reducing agent into the main combustion zone and the burnout zone respectively.
In the specific implementation process, a boiler furnace is divided into a main combustion area and a burnout area from bottom to top, the main combustion area and the burnout area in S1 are defined by a jetting port of burnout air, when the temperature in the furnace of the boiler is 1000-1300 ℃, the temperature in the furnace of the boiler is set to be 1000-1300 ℃, so that the coking degree in the furnace is minimized, the oxygen content in the furnace in S1 is 3.5-4.5 wt%, the excess air coefficient of the main combustion area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, the proper oxygen content in the furnace is 3.5-4.5 wt%, so that the smoke temperature at the outlet of the furnace is kept in a lower range, the excess air coefficient of the main combustion area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, the generation of NOx can be effectively reduced, two streams of air streams with large concentration difference are injected into the furnace, and the dense-phase air stream in S2 is jetted to the fire side of the furnace, the light-phase pulverized coal airflow is shot to the back fire side of the hearth, the dense-phase pulverized coal airflow is shot to the fire side of the hearth, the light-phase pulverized coal airflow is shot to the back fire side of the hearth to realize classification of primary air in the horizontal direction, a structure of air-coated powder is formed, slag bonding and high-temperature corrosion of a water wall can be effectively avoided, primary air and over-fire air are injected through a hearth nozzle, the reference air pressure of the primary air in S3 is 9.0-9.5 KPa, the air speed of the primary air is 30-38 m/S, the air speed and the air volume under the condition that the primary air pipe carries pulverized coal are measured to carry out pressure leveling, the air pressure of the primary air is controlled to be 9.0-9.5 KPa as the reference air pressure to carry out adjustment in normal operation, a curve that the air speed in the primary air pipe changes along with the output of the pulverized coal is drawn, the air speed of the primary air is adjusted to be 30-38 m/S, the smoke temperature at the outlet of the hearth is controlled, in actual operation adjustment, the air distribution is carried out, and the appropriate oxygen content in the hearth to be 3.5-4.5 wt%, so as to keep the smoke temperature at the outlet of the hearth in a lower range, a horizontal thick and thin nozzle is adopted for primary air and overfire air in S3, the air flow is parallel to the central axis of the hearth, the air flow direction of the sprayed primary air coal dust is parallel to the central axis of a burner, the secondary air flow is favorable for dragging the coal dust layer to prevent the coal dust from falling into a bottom ash bucket, the carbon content of bottom slag is effectively reduced, the secondary air flow and the primary coal dust air flow are ensured to be mixed in time, the oil-free stable combustion capability and the coal dust combustion efficiency of a unit in a low-load operation stage are improved, a primary amino reducing agent and a secondary amino reducing agent are respectively sprayed into a main combustion zone and an overfire zone, the molar ratio of NH3 generated by the amino reducing agent sprayed into the main combustion zone in S4 to nitrogen oxides in the flue gas of the main combustion zone is 0.5-1.1: 1, the molar ratio of NH3 generated by the amino reducing agent sprayed into the overfire zone to nitrogen oxides in the overfire flue gas of the overfire zone is 0.6-1.5: 1, compared with the conventional air staged combustion technology, the method has the advantages that the main combustion area adopts weak reducing atmosphere, slag bonding is effectively avoided when brown coal is combusted, the primary amino reducing agent is sprayed into the main combustion area in S4, the secondary amino reducing agent is sprayed into the burnout area, the solid particles of the primary amino reducing agent in S4 are ammonium bicarbonate particles with the particle size smaller than 1mm, the secondary amino reducing agent is sprayed into the burnout area in S4 and is ammonia water solution with the mass concentration of 5-20% or ammonium bicarbonate solution, the amino reducing agent is sprayed into the main combustion area, NOx in flue gas is removed by utilizing the reducing component generated during combustion in coal powder reducing atmosphere and NH generated by decomposition of the amino reducing agent in a synergistic manner, the NOx concentration of the flue gas at the outlet of the main combustion area is reduced by the weak reducing atmosphere in the main combustion area and the feeding of the amino reducing agent, the method can effectively prevent slag bonding and high-temperature corrosion of a water cooled wall of a boiler at the early stage of ensuring low pollutant emission of the boiler, the grouped arrangement of the furnace chambers is beneficial to reducing the heat load of a combustion area of the boiler, reducing the smoke temperature level of the combustion area of the boiler and effectively reducing the slag bonding and high temperature generation of the combustion area.
In the S1, the main combustion area and the burnout area use the injection port of the burnout air as a boundary, the temperature in the hearth of the boiler is 1000-1300 ℃, and when the temperature in the hearth of the boiler is set to be 1000-1300 ℃, the coking degree in the hearth is minimized.
In the S2, the dense-phase coal powder airflow is emitted to the fire side of the hearth, the light-phase coal powder airflow is emitted to the back fire side of the hearth, and the dense-phase coal powder airflow is emitted to the fire side of the hearth and the light-phase coal powder airflow is emitted to the back fire side of the hearth, so that primary air classification in the horizontal direction is realized, a wind-coated powder structure is formed, and slag bonding and high-temperature corrosion of a water-cooled wall can be effectively avoided.
In the S1, the oxygen content in the hearth is 3.5-4.5 wt%, the excess air coefficient of the main combustion area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, and the proper oxygen content in the hearth is 3.5-4.5 wt% so as to keep the smoke temperature at the outlet of the hearth in a lower range, the excess air coefficient of the main combustion area is 0.95, and the excess air coefficient of the burnout area is 1.16-1.17, so that the generation of NOx can be effectively reduced.
In S4, the molar ratio of NH3 generated by the amino reducing agent sprayed in the main combustion zone to nitrogen oxides in flue gas of the main combustion zone is 0.5-1.1: 1, and the molar ratio of NH3 generated by the amino reducing agent sprayed in the burnout zone to nitrogen oxides in flue gas of the burnout zone is 0.6-1.5: 1.
In S4, the primary combustion zone sprays primary amino reducing agent, and the burnout zone sprays secondary amino reducing agent.
In the S4, the primary amino reducing agent solid particles are ammonium bicarbonate particles, and the particle size is less than 1 mm.
The secondary amino reducing agent which is sprayed into the burnout zone in the S4 is an ammonia water solution with the mass concentration of 5% -20% or an ammonium bicarbonate solution, the amino reducing agent is sprayed into the main combustion zone, NOx in the flue gas is removed by utilizing the reduction component generated during combustion in the coal powder reducing atmosphere and NH generated by decomposition of the amino reducing agent, and the NOx concentration of the flue gas at the outlet of the main combustion zone is reduced by the weak reducing atmosphere of the main combustion zone and the feeding of the amino reducing agent.
The method comprises the steps of S3, measuring the wind speed and the wind volume of primary wind under the condition that a primary wind pipe carries pulverized coal to level the pressure, controlling the wind pressure of the primary wind to be 9.0-9.5 KPa as the reference wind pressure to adjust in normal operation, drawing a curve of the change of the wind speed in the primary wind pipe along with the output of the pulverized coal, controlling the smoke temperature of a hearth outlet by adjusting the wind speed of the primary wind to be 30-38 m/S, and finding out the proper oxygen content in the hearth to be 3.5-4.5 wt% in the adjustment of actual operation through wind distribution adjustment so as to keep the smoke temperature of the hearth outlet in a lower range.
In the S3, the primary air and the over-fire air adopt horizontal thick and thin nozzles, the air flow is parallel to the central axis of the hearth, and the air flow direction of the sprayed primary air pulverized coal is parallel to the central axis of the burner, so that the secondary air flow is favorable for dragging the pulverized coal of the layer to prevent the pulverized coal from falling into a bottom ash bucket, the carbon content of bottom slag is effectively reduced, the timely mixing of the secondary air flow and the primary pulverized coal flow can be ensured, and the oil-throwing-free stable combustion capability and the pulverized coal combustion efficiency of the unit in the low-load operation stage are improved.
The working principle of the combustion method for effectively reducing the slagging and the high-temperature corrosion of the boiler furnace provided by the invention is as follows:
dividing a boiler hearth into a main combustion area and a burnout area from bottom to top, wherein the main combustion area and the burnout area in S1 are defined by a jetting port of burnout air, when the temperature in the boiler hearth is 1000-1300 ℃, the temperature in the boiler hearth is set to be 1000-1300 ℃, so that the coking degree in the hearth is minimized, the oxygen content in the hearth in S1 is 3.5-4.5 wt%, the excess air coefficient of the main combustion area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, by finding a proper oxygen content in the hearth to be 3.5-4.5 wt%, the smoke temperature at the outlet of the hearth is kept in a lower range, the excess air coefficient of the main combustion area is 0.95, the excess air coefficient of the burnout area is 1.16-1.17, the generation of NOx can be effectively reduced, two streams of coal dust with large concentration difference are injected into the hearth, the dense-phase coal dust stream in S2 is shot to the fire side, and the light-phase coal dust stream is shot to the back fire side of the hearth, the classification of primary air in the horizontal direction is realized by arranging dense-phase pulverized coal airflow to irradiate the fire side of a hearth and light-phase pulverized coal airflow to irradiate the fire side of the hearth, so that the structure of wind-coated powder is formed, slag bonding and high-temperature corrosion of a water-cooled wall can be effectively avoided, primary air and over-fire air are sprayed through a hearth nozzle, the reference wind pressure of the primary air in S3 is 9.0-9.5 KPa, the wind speed of the primary air is 30-38 m/S, the wind speed and the wind volume under the condition that the primary air pipe carries pulverized coal are measured to carry out pressure leveling, the wind pressure of the primary air is controlled to be 9.0-9.5 KPa as the reference wind pressure to carry out adjustment in normal operation, a curve that the wind speed in the primary air pipe changes along with the output of the pulverized coal preparation is drawn, the smoke temperature at the outlet of the hearth is controlled by adjusting the wind speed of the primary air to be 30-38 m/S, in the adjustment of actual operation, the proper oxygen content in the hearth is found to be 3.5-4.5 wt% through wind distribution adjustment, so as to keep the smoke temperature at the outlet of the hearth in a lower range, a horizontal thick and thin nozzle is adopted for primary air and overfire air in S3, the air flow is parallel to the central axis of the hearth, the air flow direction of the sprayed primary air coal dust is parallel to the central axis of a burner, the secondary air flow is favorable for dragging the coal dust layer to prevent the coal dust from falling into a bottom ash bucket, the carbon content of bottom slag is effectively reduced, the secondary air flow and the primary coal dust air flow are ensured to be mixed in time, the oil-free stable combustion capability and the coal dust combustion efficiency of a unit in a low-load operation stage are improved, a primary amino reducing agent and a secondary amino reducing agent are respectively sprayed into a main combustion zone and an overfire zone, the molar ratio of NH3 generated by the amino reducing agent sprayed into the main combustion zone in S4 to nitrogen oxides in the flue gas of the main combustion zone is 0.5-1.1: 1, the molar ratio of NH3 generated by the amino reducing agent sprayed into the overfire zone to nitrogen oxides in the overfire flue gas of the overfire zone is 0.6-1.5: 1, compared with the conventional air staged combustion technology, the method has the advantages that the main combustion area adopts weak reducing atmosphere, slag bonding is effectively avoided when brown coal is combusted, the primary amino reducing agent is sprayed into the main combustion area in S4, the secondary amino reducing agent is sprayed into the burnout area, the solid particles of the primary amino reducing agent in S4 are ammonium bicarbonate particles with the particle size smaller than 1mm, the secondary amino reducing agent is sprayed into the burnout area in S4 and is ammonia water solution with the mass concentration of 5-20% or ammonium bicarbonate solution, the amino reducing agent is sprayed into the main combustion area, NOx in flue gas is removed by utilizing the reducing component generated during combustion in coal powder reducing atmosphere and NH generated by decomposition of the amino reducing agent in a synergistic manner, the NOx concentration of the flue gas at the outlet of the main combustion area is reduced by the weak reducing atmosphere in the main combustion area and the feeding of the amino reducing agent, the method can effectively prevent slag bonding and high-temperature corrosion of a water cooled wall of a boiler at the early stage of ensuring low pollutant emission of the boiler, the grouped arrangement of the furnace chambers is beneficial to reducing the heat load of a combustion area of the boiler, reducing the smoke temperature level of the combustion area of the boiler and effectively reducing the slag bonding and high temperature generation of the combustion area.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A combustion method for effectively reducing slagging and high-temperature corrosion of a boiler hearth is characterized by comprising the following steps:
s1, dividing a boiler furnace into a main combustion area and a burnout area from bottom to top;
s2, injecting two coal powder air flows with large concentration difference into the hearth;
s3, spraying primary air and over-fire air through a hearth nozzle;
and S4, spraying a primary amino reducing agent and a secondary amino reducing agent into the main combustion zone and the burnout zone respectively.
2. The combustion method for effectively reducing slagging and high-temperature corrosion of the boiler furnace according to claim 1, wherein the main combustion zone and the burnout zone in S1 are defined by an injection port of the burnout air, and the temperature in the boiler furnace is 1000-1300 ℃.
3. The combustion method for effectively reducing slagging and high-temperature corrosion of a boiler furnace according to claim 1, wherein the oxygen content in the furnace in S1 is 3.5-4.5 wt%, the excess air coefficient of the main combustion zone is 0.95, and the excess air coefficient of the burnout zone is 1.16-1.17.
4. The combustion method for effectively reducing slagging and high temperature corrosion of a boiler furnace according to claim 1, characterized in that the rich phase pulverized coal stream in S2 is directed to the fire-facing side of the furnace, and the lean phase pulverized coal stream is directed to the back fire side of the furnace.
5. The combustion method for effectively reducing slagging and high-temperature corrosion of boiler furnace according to claim 1, wherein the reference wind pressure of the primary wind in S3 is 9.0-9.5 KPa, and the wind speed of the primary wind is 30-38 m/S.
6. The combustion method for effectively reducing slagging and high temperature corrosion of boiler furnace according to claim 1, characterized in that horizontal rich and lean nozzles are adopted for primary air and over-fire air in S3, and the air flow is parallel to the central axis of the furnace.
7. The combustion method for effectively reducing the slagging of the boiler furnace and the high-temperature corrosion according to claim 1, wherein the molar ratio of NH3 generated by the amino reducing agent injected into the main combustion zone in S4 to the nitrogen oxides in the flue gas of the main combustion zone is 0.5-1.1: 1, and the molar ratio of NH3 generated by the amino reducing agent injected into the burnout zone to the nitrogen oxides in the flue gas of the burnout zone is 0.6-1.5: 1.
8. The combustion method for effectively reducing the slagging and the high-temperature corrosion of the boiler furnace according to claim 1, wherein the primary amino reducing agent is injected into the main combustion zone in S4, and the secondary amino reducing agent is injected into the burnout zone.
9. The combustion method for effectively reducing the slagging and the high-temperature corrosion of the boiler furnace according to claim 8, wherein the solid particles of the primary amino reducing agent in S4 are ammonium bicarbonate particles with the particle size of less than 1 mm.
10. The combustion method for effectively reducing the slagging of the boiler furnace and the high-temperature corrosion according to claim 8, wherein the secondary amino reducing agent injected into the burnout zone in the S4 is an ammonia solution with the mass concentration of 5-20% or an ammonium bicarbonate solution.
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