CN112013381B - Coupling double fluidized bed low-nitrogen combustion device and method - Google Patents
Coupling double fluidized bed low-nitrogen combustion device and method Download PDFInfo
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- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/005—Fluidised bed combustion apparatus comprising two or more beds
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
- C10J3/82—Gas withdrawal means
- C10J3/84—Gas withdrawal means with means for removing dust or tar from the gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
- F22B31/0007—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
- F22B31/08—Installation of heat-exchange apparatus or of means in boilers for heating air supplied for combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/008—Adaptations for flue gas purification in steam generators
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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
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/18—Details; Accessories
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0953—Gasifying agents
- C10J2300/0973—Water
- C10J2300/0976—Water as steam
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/16—Integration of gasification processes with another plant or parts within the plant
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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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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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Abstract
The invention discloses a coupling double fluidized bed low-nitrogen combustion device, which comprises a combustion unit, a gasification unit, a reburning denitration burnout zone and a tail flue, wherein the afterburning unit is connected with the tail flue; the inlet of the reburning denitration burnout area is respectively communicated with the outlet of the combustion unit and the outlet of the gasification unit; an outlet of the reburning denitration burnout area is communicated with an inlet of the tail flue; and at least one post-combustion air nozzle is arranged on the side wall of the reburning denitration burnout area. The invention also discloses a coupled double fluidized bed low-nitrogen combustion method, and by using the device, NOx generated in the flue gas of the combustion chamber and coal gas generated by the gasification chamber are subjected to denitration reduction reaction in a reburning denitration post-combustion zone, so that most of NOx in the flue gas is reduced, and low-nitrogen combustion is realized. The invention has the advantages that: the reducing agent is provided for the coal-fired combustion denitration reaction through the gasification of the solid wastes, so that the original emission concentration of NOx and the denitration cost are obviously reduced, and the resource utilization of the solid wastes is realized.
Description
Technical Field
The invention belongs to the technical field of clean and efficient combustion of coal, and particularly relates to a coupling double fluidized bed low-nitrogen combustion device and method.
Background
China is the largest coal producing country and consuming country in the world, and the coal yield reaches 37.5 hundred million tons in 2019, which accounts for 57.7 percent of primary energy consumption. From the energy resource and economic development level of China, coal is still the most main primary energy of China for a long time. According to statistics, 70 percent of the discharge amount of nitrogen oxides (NOx) in China comes from the combustion of coal, so the development of clean and efficient combustion technology of the coal is obviousIs particularly important and urgent. With the promulgation and implementation of the national emission Standard of atmospheric pollutants for thermal Power plants (GB 13223-2011), the emission of NOx is to be carried out at 100mg/m 3 The concentration standard of (A) is up to 50mg/m for the heavy spot area and even the strict requirement 3 This presents a significant challenge to the operation of coal-fired boilers. At present, the technical measures for reducing NOx emission of coal-fired boilers are mainly divided into three categories: (1) The in-furnace low-nitrogen combustion technology comprises a low NOx burner, an air classification and fuel classification technology, a thick and thin combustion technology, a flue gas recirculation technology and the like, for example, chinese patent 201610614713.6 discloses a flue gas recirculation low-nitrogen combustion method and a system for an industrial pulverized coal boiler, and the ignition stability of pulverized coal is improved on the premise that the same emission reduction effect can be obtained; however, the denitration efficiency of the in-furnace low-nitrogen combustion technology is only 10-30%, and the requirements of emission standards cannot be met. (2) Tail flue gas denitration technologies, including Selective Catalytic Reduction (SCR), selective Catalytic Reduction (SCR) and selective non-catalytic reduction (SNCR) combination, activated carbon denitration, and the like, although the denitration efficiency can reach 70 to 90%, a complicated flue gas denitration treatment system needs to be configured, an additional reducing agent and a catalyst need to be provided, the system is complicated, the investment, operation and maintenance costs are high, and secondary pollution, such as ammonia escape, is caused. (3) A novel hearth structure is developed, for example, a double-hearth pulverized coal gasification low-nitrogen combustion industrial boiler disclosed in Chinese patent CN201610745593.3 adopts a double-hearth structure, so that pulverized coal combustion has sufficient gasification space and burnout space, and NOx emission is reduced by improving bed temperature distribution uniformity; chinese patent CN201811603352.0 discloses a pulverized coal pre-pyrolysis low NOx boiler combustion system, which couples low NOx combustion technologies such as pulverized coal pre-combustion, gasification, flue gas recirculation and air classification, so that it exerts a synergistic denitration effect. But the novel hearth has a complex structure, high investment, development and operation cost and higher requirement on the stability of boiler operation.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a coupling double fluidized bed low-nitrogen combustion device and a coupling double fluidized bed low-nitrogen combustion method.
In order to achieve the above object, the present invention adopts the following technical solutions:
a coupling double fluidized bed low-nitrogen combustion device comprises a combustion unit, a gasification unit, a reburning denitration burnout area and a tail flue; the combustion unit and the gasification unit are arranged independently; the reburning denitration burnout area is provided with two inlets which are respectively communicated with the outlet of the combustion unit and the outlet of the gasification unit; an outlet of the reburning denitration burnout area is communicated with an inlet of the tail flue; and at least one post-combustion air nozzle is arranged on the side wall of the reburning denitration burnout area.
Preferably, two inlets of the reburning denitration burnout area are oppositely arranged, so that the substance flowing out of the gas-phase outlet of the combustion unit and the substance flowing out of the gas-phase outlet of the gasification unit enter the two inlets to form opposite contact.
Preferably, the combustion unit comprises a combustion chamber and a first cyclone separator; the gasification unit comprises a gasification chamber and a second cyclone separator; the inlet of the first cyclone separator is communicated with the outlet of the combustion chamber, the gas phase outlet of the first cyclone separator is the gas phase outlet of the combustion unit, and a first flue is arranged on the gas phase outlet of the first cyclone separator; the inlet of the second cyclone separator is communicated with the outlet of the gasification chamber, the gas phase outlet at the upper part of the second cyclone separator is the gas phase outlet of the gasification chamber, and a second flue is arranged on the gas phase outlet; the first flue outlet and the second flue outlet are two inlets of the reburning denitration burnout area.
Preferably, the first flue and the second flue are both horizontal flues, and the connection mode of the communication is rectangular, kidney-shaped or prismatic.
Preferably, the combustion unit further comprises a first return feeder, and the gasification unit further comprises a second single-side return feeder; the inlet of the first material returning device is communicated with the solid phase outlet at the lower part of the first cyclone separator; the outlet of the first material returning device is communicated with a material returning port of a rear wall at the lower part of the combustion chamber; and the inlet of the second single-side material returning device is communicated with the solid phase outlet at the lower part of the second cyclone separator through a vertical pipe, and the outlet of the second single-side material returning device is communicated with a material returning port at the lower part of the gasification chamber.
Preferably, the lower part of the tail flue is sequentially provided with a superheater, an economizer and an air preheater from top to bottom; the superheater outlet pipeline is communicated with a water vapor nozzle on the side wall of a second air chamber at the bottom of the gasification chamber; the outlet pipeline of the air preheater is communicated with an air inlet pipeline of an air chamber at the bottom of the gasification chamber; and an outlet below the reburning denitration burnout area is communicated with an inlet flue of the superheater.
Preferably, the excess air coefficient of the main combustion area of the combustion chamber is 1.0-1.05; the reaction temperature of the gasification chamber is 900-1000 ℃.
Preferably, the excess air coefficient of the reburning denitration burnout area is 1.05-1.15, the reaction temperature is 900-1100 ℃, the retention time of the flue gas is 0.5-1.5 s, the flow rate of the coal gas is not lower than that of the flue gas, and the proportion of the heat of the coal gas to the total input heat is 10-30%.
Preferably, the device also comprises a third cyclone separator and a third return feeder; the gas phase outlet at the upper part of the second cyclone separator is respectively communicated with the inlet of the second flue and the inlet of the third cyclone separator; a solid phase outlet at the lower part of the third cyclone separator is communicated with an inlet of a third material returning device, and a gas phase outlet at the upper part of the third cyclone separator is communicated with a tail gas pipeline; and the outlet of the third material returning device is communicated with the feeding port of the first coal feeder at the lower part of the combustion chamber.
Preferably, the gasification chamber is replaced by a pyrolysis chamber and the second single-sided return feeder is replaced by a second double-sided return feeder.
Preferably, the combustion chamber is a fluidized bed hearth or a pulverized coal hearth.
Preferably, the reaction temperature of the pyrolysis chamber is 550-650 ℃, and the proportion of the heat of the pyrolysis gas in the reburning denitration area to the total input heat is 10-25%.
The coupled double fluidized bed low-nitrogen combustion method using the coupled double fluidized bed low-nitrogen combustion device is characterized by comprising the following steps of:
providing a coupling double fluidized bed low-nitrogen combustion device;
feeding primary fuel from the lower part of the combustion unit, and performing combustion reaction under the action of primary hot air and secondary hot air;
feeding secondary fuel from the lower part of the gasification unit, and performing gasification reaction under the action of primary hot air and superheated steam gasification agent;
fourthly, carrying out denitration reduction reaction on NOx in the flue gas generated by the combustion unit and the coal gas generated by the gasification unit in the reburning denitration region, and reducing most of NOx in the flue gas into nitrogen;
fifthly, feeding the gasified bottom slag generated by the gasification unit into the lower part of the combustion unit for reburning under the conveying action of hot air;
sixthly, fully combusting and reacting unburned carbon residue particles and carbon monoxide gas in the reburning denitration burnout zone under the action of afterburning air; and the high-temperature flue gas leaves the reburning denitration burnout area, exchanges heat through the tail flue, and is subjected to dust removal, purification and evacuation.
Preferably, the fuel used by the combustion unit and the gasification unit comprises one or more of bituminous coal, lignite, anthracite, biomass, semi-coke/semi-coke, coal slurry, coal gangue, gasification fly ash or coal water slurry.
The invention has the advantages that:
(1) The reburning denitration area is arranged, and a large amount of cheap reducing agent (CH) generated by the fuel thermochemical conversion process is used 4 、H 2 CO, semicoke and the like) to carry out deep denitration reduction reaction on NOx generated in the fuel combustion process, and the original emission concentration of NOx, denitration investment and operation cost generated in the fuel combustion process of the system are obviously reduced.
(2) The first flue at the outlet of the combustion chamber and the second flue at the outlet of the gasification chamber are arranged in a hedging manner, so that the mixing strength of the flue gas flow and the coal gas flow is enhanced, the reduction efficiency of NOx in the flue gas is improved, and the original emission concentration of NOx is obviously reduced.
(3) The fuel of the combustion chamber and the gasification chamber can be the same fuel or different fuels, the gasification chamber adopts solid waste low-heat value fuel, a large amount of cheap reducing agents are provided for the combustion denitration reaction of the coal through the gasification of the solid waste, and the resource utilization of the solid waste is realized; the gasified ash slag generated in the gasification reaction process is returned to the combustion chamber for full combustion, the whole system does not generate solid waste and waste water, and the resource utilization of the solid waste is further improved.
(4) The combustion chamber and the gasification chamber are mutually independent, and the combustion chamber and the gasification chamber can be independently and accurately adjusted according to the requirements of reaction temperature and reaction atmosphere in each zone, so that the adjustment flexibility and the operation stability of the system are improved.
(5) By adding the post-combustion air, the CO and the carbon residue which are not completely reacted in the main combustion area and the denitration area are subjected to secondary full combustion reaction in the post-combustion high-temperature area, so that the combustion efficiency and the energy conversion efficiency of the system are ensured.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment 1 of a coupled dual fluidized bed low nitrogen combustion apparatus of the present invention;
FIG. 2 is a schematic diagram of three configurations of a reburning denitrification zone of the coupled dual fluidized bed low nitrogen combustion apparatus of FIG. 1;
FIG. 3 is a schematic structural diagram of embodiment 2 of the coupled dual fluidized bed low nitrogen combustion apparatus of the present invention;
FIG. 4 is a schematic structural diagram of embodiment 3 of the coupled dual fluidized bed low nitrogen combustion apparatus of the present invention;
FIG. 5 is a schematic structural diagram of embodiment 4 of the coupled dual fluidized bed low nitrogen combustion apparatus of the present invention.
The meanings indicated in the figures are: 1-a combustion chamber; 11-a first coal feeder; 12-a circulating semicoke feeding port; 2-a first cyclone separator; 21-a first flue; 3-a first material returning device; 4-a gasification chamber; 4' -a pyrolysis chamber; 41-a second coal feeder; 5-a second cyclone separator; 51-a second flue; 52-a third cyclone; 53-third return feeder; 6-a second single-side material returning device; 6' -a second bilateral return feeder; 7-a superheater; 8-a coal economizer; 9-an air preheater; a-a main combustion zone; b, a reburning denitration area; d-post-combustion burnout zone; c, a gasification zone; c1-a pyrolysis zone; PA-primary hot air; TA-post combustion air; EG-flue gas; SW-superheated steam; SC-semicoke; CG-gas; BS-bottom slag; v1, flue gas flow rate; v2-gas flow rate.
Detailed Description
The invention is further described in detail below with reference to the drawings and the embodiments.
Example 1
A coupling double fluidized bed low-nitrogen combustion device is shown in figure 1 and comprises a combustion unit, a gasification unit, a reburning denitration burnout zone and a tail flue; the combustion unit and the gasification unit are arranged independently; the reburning denitration burnout area is provided with two inlets which are respectively communicated with the outlet of the combustion unit and the outlet of the gasification unit; an outlet of the reburning denitration burnout area is communicated with an inlet of the tail flue; and at least one post-combustion air nozzle is arranged on the side wall of the middle lower part of the reburning denitration burnout area.
Wherein the combustion unit comprises a combustion chamber 1 (a circulating fluidized bed hearth), a first cyclone separator 2 and a first return feeder 3; the gasification unit comprises a gasification chamber 4, a second cyclone separator 5 and a second single-side material returning device 6; a feeding port of a first coal feeder 11 is arranged on the front wall of the lower part of the combustion chamber 1, a material returning port is arranged on the rear wall of the lower part, an outlet of the combustion chamber is arranged on the rear wall of the upper part, and a first air chamber is arranged at the bottom; an air inlet is formed in the side wall of the first air chamber; an inlet of the first cyclone separator 2 is communicated with an outlet of the combustion chamber at the upper part of the combustion chamber 1, and a gas phase outlet at the upper part of the first cyclone separator 2 is communicated with an inlet of the first flue 21; an inlet of the first material returning device 3 is communicated with a solid phase outlet at the lower part of the first cyclone separator 2 through a vertical pipe, and an outlet of the first material returning device 3 is communicated with a material returning port at the lower part of the rear wall of the combustion chamber 1; a feeding port of a second coal feeder 41 is arranged on the front wall of the lower part of the gasification chamber 4, a material return port is arranged on the rear wall of the lower part, an outlet of the gasification chamber is arranged on the rear wall of the upper part, and a second air chamber is arranged at the bottom; an air inlet and a water vapor nozzle are formed in the side wall of the second air chamber; an inlet of the second cyclone separator 5 is communicated with an outlet of the gasification chamber at the upper part of the gasification chamber 4, and a gas phase outlet at the upper part of the second cyclone separator 5 is communicated with an inlet of the second flue 51; an inlet of the second single-side material returning device 6 is communicated with a solid phase outlet at the lower part of the second cyclone separator 5 through a vertical pipe, and an outlet of the second single-side material returning device 6 is communicated with a material returning opening at the lower rear wall of the gasification chamber 4.
The lower part of the tail flue is sequentially provided with a superheater 7, an economizer 8 and an air preheater 9 from top to bottom; an outlet pipeline of the superheater 7 is communicated with a water vapor nozzle on the side wall of a second air chamber at the bottom of the gasification chamber 4; the outlet pipeline of the air preheater 9 is communicated with the air inlet pipeline of the air chamber at the bottom of the gasification chamber 4.
The upper part of the reburning denitration burnout zone is a reburning denitration zone B, and the lower part of the reburning denitration burnout zone is a post burnout zone D; combustion chamber 1 and vaporizer 4 are independent each other, and combustion chamber 1 and vaporizer 4 can carry out accurate regulation alone according to each district's reaction temperature and the demand of reaction atmosphere, have improved the stability of the regulation flexibility and the operation of system.
The outlet of the first flue 21 and the outlet of the second flue 51 are two inlets of the reburning denitration burnout area, the first flue 21 and the second flue 51 are both horizontal flues, and the outlet of the first flue 21 and the outlet of the second flue 51 are arranged in a hedging manner; the first flue 21 at the outlet of the circulating fluidized bed combustion chamber 1 and the second flue 51 at the outlet of the gasification chamber 4 are arranged in a hedging mode, so that the mixing strength of the flue gas flow and the coal gas flow is enhanced, the reduction efficiency of NOx in the flue gas is improved, and the original emission concentration of NOx is obviously reduced.
An outlet below the reburning denitration burnout area B is communicated with an inlet flue of the superheater 7, and a rear burning air nozzle is arranged on the side wall of the middle lower part; by adding the post-combustion air TA, the CO and the carbon residue which are not completely reacted in the main combustion area A and the reburning denitration area B of the combustion chamber 1 are subjected to secondary sufficient combustion reaction in a post-combustion high-temperature area, so that the combustion efficiency and the energy conversion efficiency of the system are ensured.
And the post-combustion air nozzles of the reburning denitration burnout area are arranged along the peripheral direction of the side wall of the reburning denitration burnout area, and the number of the post-combustion air nozzles is more than or equal to 1.
As shown in FIG. 2, the connection mode of the first flue 21 outlet and the second flue 51 outlet is rectangular, kidney-shaped or prismatic.
The fuels of the combustion chamber 1 and the gasification chamber 4 comprise one or more of bituminous coal, lignite, anthracite, biomass, semicoke, coal slime, coal gangue, gasification fly ash or coal water slurry; the fuel of the combustion chamber 1 and the gasification chamber 4 can be the same fuel or different fuels, the gasification chamber 4 adopts solid waste low-heat value fuel, and a large amount of cheap reducing agents are provided for the combustion denitration reaction of coal by gasifying the solid waste in the gasification zone C of the gasification chamber 4, so that the resource utilization of the solid waste is realized.
The excess air coefficient of the main combustion area A of the combustion chamber 1 is 1.0-1.05.
The excess air coefficient of the reburning denitration burnout area is 1.05-1.15, the reaction temperature is 900-1100 ℃, the flue gas retention time is 0.5-1.5 s, the gas flow rate V2 is not lower than the flue gas flow rate V1, and the proportion of the gas heat to the total input heat is 10-30%.
The reaction temperature of the gasification chamber 4 is 900 ℃ to 1000 ℃.
The coupled double fluidized bed low-nitrogen combustion method using the coupled double fluidized bed low-nitrogen combustion device comprises the following steps of:
step one, providing a coupled double fluidized bed low-nitrogen combustion device;
feeding primary fuel from the lower part of the combustion chamber 1, and performing combustion reaction under the action of primary hot air PA and secondary hot air;
feeding secondary fuel from the lower part of the gasification chamber 4, and performing gasification reaction under the action of primary hot air PA and superheated steam SW gasifying agent;
step four, NOx in the flue gas generated by the combustion chamber 1 and coal gas generated by the gasification chamber 4 are subjected to denitration reduction reaction in the reburning denitration zone B, and most of NOx in the flue gas is reduced into nitrogen;
step five, the gasification bottom slag BS generated by the gasification chamber 4 is conveyed to the lower part of the combustion chamber 1 for reburning under the hot air conveying action; the gasified ash slag generated in the gasification reaction process is returned to the combustion chamber for full combustion, so that the whole system does not generate solid waste and wastewater, and the resource utilization of the solid waste is further improved;
sixthly, fully combusting the carbon residue particles which are not combusted completely in the reburning denitration area B and carbon monoxide gas under the action of afterburning air TA; the high-temperature flue gas leaves the post-combustion burnout zone D, exchanges heat with the superheater 7, the economizer 8 and the air preheater 9 in sequence, and is subjected to dust removal, purification and evacuation;
through TA classification of post-combustion air, a high-temperature low-oxygen environment with the temperature of 900-1000 ℃ and the temperature of alpha = 0.95-1.05 is provided at the upper part of a post-combustion burnout zone D, and the reduction reaction rate and the NOx reduction rate are improved; and through the injection of post-combustion air TA, a high-temperature oxidizing atmosphere (900-1000 ℃, alpha = 1.05-1.15) is provided, so that the sufficient combustion of carbon residue and CO is ensured, the combustion efficiency of the system is improved, and the high-efficiency ultralow-nitrogen combustion target is realized.
In the present embodiment of the present invention,the primary fuel is subjected to combustion reaction in the main combustion area A through a first coal feeder 11 under the action of primary hot air PA, combustion products after the combustion reaction are subjected to gas-solid separation through a first cyclone separator 2, and flue gas after the gas-solid separation enters a reburning denitration burnout area B from the upper part of the first cyclone separator 2; the secondary fuel enters the gasification chamber 4 through a second coal feeder 41, hot air preheated by the air preheater 9 and superheated steam heated by the superheater 7 are used as gasification agents, the secondary fuel is subjected to gasification reaction, the gasified product enters a second cyclone separator 5 for gas-solid separation, and the reducing gas CH in the separated coal gas 4 、H 2 CO and the like enter the upper part of the reburning denitration burnout zone B to denitrate and reduce NOx generated in the combustion chamber 1 into N 2 。
According to the invention, a large amount of cheap reducing agents are generated in the coal gasification process, the reaction temperature and the reaction atmosphere are controlled in a subarea manner through the reburning denitration burnout area of the tail flue of the coupling combustion chamber 1 and the gasification chamber 4, the low-cost efficient ultralow-nitrogen combustion is realized, the original emission concentration of NOx generated in the combustion process is greatly reduced, and no solid waste or wastewater is discharged in the whole system.
Example 2
Example 3
And a part of the semicoke SC discharged from the second double-side material returning device 6' returns to the pyrolysis zone C1 of the pyrolysis chamber 4' to continuously participate in the pyrolysis reaction, and the other part of the semicoke SC discharged from the second double-side material returning device 6' returns to the middle lower part of the combustion chamber 1 through the circulating semicoke feeding port 12 under the conveying action of primary hot air PA discharged from the air preheater 9 to be used as reburning fuel, so that the NOx generated by bottom combustion is subjected to a first-stage denitration reduction reaction. Flue gas from the first cyclone separator 2 and pyrolysis gas from the second cyclone separator 5 are intensively mixed in the reburning denitration area B to generate a second-stage denitration reduction reaction.
And a part of high-temperature flue gas EG at 800-950 ℃ from the reburning denitration burnout zone provides a heat source required by the pyrolysis reaction for the pyrolysis chamber 4'.
The reaction temperature of the pyrolysis chamber 4' is 550-650 ℃, and the proportion of the heat of the pyrolysis gas in the reburning denitration area B to the total input heat is 10-25%.
Example 4
On the basis of the first embodiment, the fluidized bed furnace chamber is changed into a pulverized coal furnace chamber, the coal feeder 10 is communicated with the coal mill 9 through a pipeline, the coal mill 9 is communicated with the fuel nozzle A of the main combustion area through a pipeline, and the slag discharge port at the bottom of the gasification chamber is communicated with the feed port of the coal mill 9 through a pipeline.
It should be noted that the above-mentioned embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the protection scope of the present invention.
Claims (13)
1. A coupling double fluidized bed low-nitrogen combustion device is characterized by comprising a combustion unit, a gasification unit, a reburning denitration burnout zone and a tail flue; the combustion unit and the gasification unit are arranged independently; the reburning denitration burnout zone comprises a reburning denitration zone and a post-burning burnout zone; the reburning denitration area is provided with two inlets which are respectively communicated with the outlet of the combustion unit and the outlet of the gasification unit; an outlet of the reburning denitration burnout area is communicated with an inlet of the tail flue; the side wall of the post-combustion burnout area is provided with at least one post-combustion air nozzle; and the two inlets of the reburning denitration area are oppositely arranged, so that the substance flowing out of the gas-phase outlet of the combustion unit and the substance flowing out of the gas-phase outlet of the gasification unit enter the two inlets to form opposite contact.
2. A combustion unit according to claim 1, characterized in that the combustion unit comprises a combustion chamber (1) and a first cyclone (2); the gasification unit comprises a gasification chamber (4) and a second cyclone separator (5); an inlet of the first cyclone separator (2) is communicated with an outlet of the combustion chamber (1), a gas phase outlet of the first cyclone separator (2) is a gas phase outlet of the combustion unit, and a first flue (21) is arranged on the gas phase outlet; an inlet of the second cyclone separator (5) is communicated with an outlet of the gasification chamber (4), a gas phase outlet at the upper part of the second cyclone separator (5) is a gas phase outlet of the gasification chamber, and a second flue (51) is arranged on the gas phase outlet; and the outlet of the first flue (21) and the outlet of the second flue (51) are two inlets of the reburning denitration area.
3. The combustion device as claimed in claim 2, wherein the first flue (21) and the second flue (51) are horizontal flues, and the connection mode of the flues is rectangular, kidney-shaped or prismatic.
4. The combustion device according to claim 3, wherein the combustion unit further comprises a first return feeder (3), the gasification unit further comprises a second single-sided return feeder (6); an inlet of the first material returning device (3) is communicated with a solid phase outlet at the lower part of the first cyclone separator (2); the outlet of the first material returning device (3) is communicated with a material returning port of the rear wall at the lower part of the combustion chamber (1); an inlet of the second single-side material returning device (6) is communicated with a solid phase outlet at the lower part of the second cyclone separator (5) through a vertical pipe, and an outlet of the second single-side material returning device (6) is communicated with a material returning opening at the lower part of the rear wall of the gasification chamber (4).
5. The combustion device as claimed in claim 4, wherein the lower part of the tail flue is provided with a superheater (7), an economizer (8) and an air preheater (9) in sequence from top to bottom; an outlet pipeline of the superheater (7) is communicated with a water vapor nozzle on the side wall of an air chamber at the bottom of the gasification chamber (4); the outlet pipeline of the air preheater (9) is communicated with an air inlet pipeline of an air chamber at the bottom of the gasification chamber (4); and an outlet below the reburning denitration burnout area is communicated with an inlet flue of the superheater (7).
6. The combustion unit according to any of the claims 2 to 5, characterised in that the combustion chamber (1) has a main combustion zone excess air ratio of 1.0-1.05; the reaction temperature of the gasification chamber (4) is 900-1000 ℃.
7. The combustion device as claimed in claim 6, wherein the excess air coefficient of the reburning denitration burnout zone is 1.05-1.15, the reaction temperature is 900-1100 ℃, the flue gas residence time is 0.5-1.5 s, the gas flow rate is not lower than the flue gas flow rate, and the proportion of the gas heat to the total input heat is 10-30%.
8. The combustion unit according to any of the claims 2 to 4, further comprising a third cyclone (52) and a third return feeder (53); the gas phase outlet at the upper part of the second cyclone separator (5) is respectively communicated with the inlet of a second flue (51) and the inlet of a third cyclone separator (52); a solid phase outlet at the lower part of the third cyclone separator (52) is communicated with an inlet of a third material returning device (53), and a gas phase outlet at the upper part of the third cyclone separator (52) is communicated with a tail gas pipeline; the outlet of the third material returning device (53) is communicated with the feeding port of the first coal feeder (11) at the lower part of the combustion chamber (1).
9. The combustion unit according to any of claims 2 to 4, characterized in that the gasification chamber (4) is replaced by a pyrolysis chamber (4 ') and the second single-sided return feeder (6) is replaced by a second double-sided return feeder (6').
10. A combustion unit according to any one of claims 2-4, characterized in that the combustion chamber (1) is a fluidized bed furnace or a pulverized coal furnace.
11. The combustion apparatus as claimed in claim 9, wherein the reaction temperature of the pyrolysis chamber is 550 to 650 ℃, and the heat of the pyrolysis gas in the reburning denitration region accounts for 10 to 25% of the total input heat.
12. A coupled dual fluidized bed low nitrogen combustion method of coupled dual fluidized bed low nitrogen combustion apparatus, characterized in that the combustion apparatus of any of claims 1 to 11 is used, the method comprising the steps of:
providing a coupling double fluidized bed low-nitrogen combustion device;
feeding primary fuel from the lower part of the combustion unit, and performing combustion reaction under the action of primary hot air and secondary hot air;
feeding secondary fuel from the lower part of the gasification unit, and performing gasification reaction under the action of primary hot air and superheated steam gasification agent;
fourthly, carrying out denitration reduction reaction on NOx in the flue gas generated by the combustion unit and the coal gas generated by the gasification unit in the reburning denitration region, and reducing most of NOx in the flue gas into nitrogen;
fifthly, feeding the gasified bottom slag generated by the gasification unit into the lower part of the combustion unit for reburning under the conveying action of hot air;
sixthly, fully combusting and reacting unburned carbon residue particles and carbon monoxide gas in the reburning denitration burnout zone under the action of afterburning air; and the high-temperature flue gas leaves the reburning denitration burnout area, exchanges heat through the tail flue, and is subjected to dust removal, purification and evacuation.
13. The method of claim 12, wherein the fuel used in the combustion unit and the gasification unit comprises one or more of bituminous coal, lignite, anthracite, biomass, semi-coke/semi-coke, coal slurry, coal gangue, gasification fly ash, or coal water slurry.
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