CN114543081A - System for reducing nitrogen oxides of biomass-fired circulating fluidized bed - Google Patents

System for reducing nitrogen oxides of biomass-fired circulating fluidized bed Download PDF

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Publication number
CN114543081A
CN114543081A CN202210278691.6A CN202210278691A CN114543081A CN 114543081 A CN114543081 A CN 114543081A CN 202210278691 A CN202210278691 A CN 202210278691A CN 114543081 A CN114543081 A CN 114543081A
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China
Prior art keywords
pipeline
air
recirculation
communicated
recirculating
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CN202210278691.6A
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Chinese (zh)
Inventor
张艳伟
蔡晓锋
林欣
吕岩岩
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Shanghai Industrial Boiler Research Institute Co ltd
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Shanghai Industrial Boiler Research Institute Co ltd
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Priority to CN202210278691.6A priority Critical patent/CN114543081A/en
Publication of CN114543081A publication Critical patent/CN114543081A/en
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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
    • F23C10/02—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed
    • F23C10/04—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone
    • F23C10/08—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases
    • F23C10/10—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases the separation apparatus being located outside the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B80/00—Combustion apparatus characterised by means creating a distinct flow path for flue gases or for non-combusted gases given off by the fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B80/00—Combustion apparatus characterised by means creating a distinct flow path for flue gases or for non-combusted gases given off by the fuel
    • F23B80/02—Combustion apparatus characterised by means creating a distinct flow path for flue gases or for non-combusted gases given off by the fuel by means for returning flue gases to the combustion chamber or to the combustion zone
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00—Arrangements of devices for treating smoke or fumes
    • F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00—Arrangements of devices for treating smoke or fumes
    • F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
    • F23J15/022—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material for removing solid particulate material from the gasflow
    • F23J15/027—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material for removing solid particulate material from the gasflow using cyclone separators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00—Arrangements of devices for treating smoke or fumes
    • F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)

Abstract

The invention discloses a system for reducing nitrogen oxides of a biomass-fired circulating fluidized bed.A recirculating main pipeline is communicated with a flue gas outlet main pipeline of the biomass-fired circulating fluidized bed; one end of the recirculation primary air distribution pipeline is communicated with the recirculation main pipeline, and the other end of the recirculation primary air distribution pipeline is communicated with the primary fluidizing air chamber inlet at the bottom of the hearth through an air preheater; one end of the recirculation secondary air branch pipeline is communicated with the recirculation main pipeline, and the other end of the recirculation secondary air branch pipeline is communicated with a secondary air inlet in the middle of the hearth through an air preheater; one end of the recirculation denitration system branch pipeline is communicated with the recirculation main pipeline, and the other end of the recirculation denitration system branch pipeline is communicated with the denitrification device; the primary air pipeline is communicated with a recirculation primary air branch pipeline and a recirculation secondary air branch pipeline respectively after passing through an air preheater; the reburning air conveying pipeline is communicated with a reburning air inlet at the upper part of the hearth after sequentially passing through the air preheater and the reburning air layering pipeline. The system can reduce the generation of NOx, improve the efficiency of the boiler, reduce the consumption of fuel, increase the peak regulation capacity of the boiler and reduce the operation cost.

Description

System for reducing nitrogen oxides of biomass-fired circulating fluidized bed
Technical Field
The invention relates to the technical field of controlling emission of nitrogen oxides by a biomass-fired circulating fluidized bed boiler, in particular to a system for reducing nitrogen oxides of a biomass-fired circulating fluidized bed.
Background
The biomass fuel is a renewable carbon source, has the characteristics of wide source, good combustion performance, less harmful gas emission, relatively low price and the like, and basically realizes CO2Zero emission, reduced particulate matter emission, obviously improved combustion characteristics and obviously improved utilization efficiency. Therefore, with the stricter environmental protection policy of the country, the biomass fuel is one of effective ways for realizing energy conservation and emission reduction instead of other fossil fuels. The understanding of biomass has been misleading for many years, with the exception of the most significant CO for biomass fuels2Due to the zero emission characteristic, biomass fuels are generally considered to have a low nitrogen content.
In practice, most biomass has a nitrogen content of 0.5% to 5% higher than that of coal. The biomass fuel inevitably emits nitrogen oxides in the combustion process, and more researches show that the nitrogen oxides emitted by the biomass in the combustion process cannot be ignored. However, the biomass boiler is influenced by factors such as fuel characteristics, and the like, and has low smoke temperature and high content of alkali metal and fly ash. If the selective catalytic reduction method (SCR) and the selective non-catalytic reduction method (SNCR) deep denitration method commonly used on a coal-fired unit is adopted, the catalytic reaction temperature is not enough, the problems of catalyst poisoning, blockage and abrasion of a denitration device and the like are easy to occur, and finally the NOx emission exceeds the standard.
Currently, methods for controlling NOx emissions can be divided into pre-combustion denitration, in-combustion denitration, and flue gas denitration. The flue gas denitration is the most efficient denitration technology, but the denitration cost is high, and the process is complex. Denitration in combustion is a preferred method of reducing boiler nitrogen oxides with certainty in terms of economy. Most of the NOx is formed in the combustion stage, which oxidizes the reducing gasThe atmosphere has a large impact on fuel nitrogen conversion. Under reducing atmosphere, most of the fuel nitrogen is converted into N2But also increases the generation amount of CO, increases the usage amount of fuel, has lower boiler efficiency and increases the operating cost of the boiler.
Disclosure of Invention
The invention aims to provide a system for reducing nitrogen oxides of a biomass-fired circulating fluidized bed, which can reduce the generation of NOx, improve the efficiency of a boiler, reduce the consumption of fuel, increase the peak shaving capacity of the boiler and reduce the operation cost.
In order to achieve the above object, the present invention provides a system for reducing nitrogen oxides in a circulating fluidized bed combusting biomass, the system comprising: a flue gas recirculation system and a flue gas reburning system; wherein the flue gas recirculation system comprises: the main recirculating pipeline is communicated with a main flue gas outlet pipeline of the boiler and is used for leading out low-oxygen and low-temperature flue gas in the main flue gas outlet pipeline; one end of the recirculation primary air branch pipeline is communicated with the recirculation main pipeline, and the other end of the recirculation primary air branch pipeline is connected with the air outlet preheater end of the primary air pipeline and then communicated with the primary fluidization air chamber inlet at the bottom of the hearth; one end of the recirculation secondary air branch pipeline is communicated with the recirculation main pipeline, and the other end of the recirculation secondary air branch pipeline is communicated with a secondary air inlet in the middle of the hearth; one end of the recirculation denitration system branch pipeline is communicated with the recirculation main pipeline, and the other end of the recirculation denitration system branch pipeline is communicated with a denitrification device; the primary air pipeline is communicated with the recirculation primary air branch pipeline after passing through the air preheater; the flue gas reburning system comprises: the reburning air conveying pipeline is communicated with a reburning air inlet at the upper part of the hearth after sequentially passing through the air preheater and the reburning air layering pipeline.
Preferably, install recirculation fan on the main pipeline of recirculating, recirculation fan is used for carrying out the pressure boost to the low oxygen low temperature flue gas in the main pipeline of recirculating.
Preferably, the recirculation fan is arranged at the rear end of the induced draft fan; and the recirculation main pipeline is positioned at the front end of the recirculation fan, the recirculation primary air branch pipeline, the recirculation secondary air branch pipeline, the recirculation denitration system branch pipeline and the reburning air layered pipeline are respectively provided with an electric adjusting baffle.
Preferably, at least one filter is arranged on the outlet pipeline of the fourth electric adjusting baffle on the recycling denitration system branch pipeline.
Preferably, be provided with first governing valve on the entry pipeline of recirculation trunk line, be provided with the second governing valve on the reburning wind layering pipeline, be provided with the third governing valve on the secondary air of recirculating branch pipeline, be provided with the fourth governing valve on the primary air of recirculating branch pipeline, be provided with the fifth governing valve on the exit pipeline of recirculation trunk line, be provided with the sixth governing valve on the denitration system of recirculating branch pipeline.
Preferably, the secondary air inlet is provided with a secondary air supply pipeline; the secondary air supply pipeline comprises: the main pipeline is communicated with the recirculation secondary air branch pipeline, and the branch pipeline is communicated with one side of the main pipeline; a first U-shaped pipeline which bypasses from the front side of the hearth is communicated between the main pipeline and the branch pipeline, and a second U-shaped pipeline which bypasses from the rear side of the hearth is communicated between the branch pipeline and the branch pipeline; the first U-shaped pipeline is provided with a plurality of first air supply pipes extending into the hearth from the front side of the hearth in an arrayed mode, and the second U-shaped pipeline is provided with a plurality of second air supply pipes extending into the hearth from the rear side of the hearth in an arrayed mode.
Preferably, a temperature sensor, a pressure sensor and an air gauge are arranged on the recirculation primary air branch pipeline, the recirculation secondary air branch pipeline, the recirculation denitration system branch pipeline and the reburning air layering pipeline, and a temperature sensor and a pressure sensor are arranged on the recirculation main pipeline.
Preferably, stainless steel expansion joints are arranged on the recycling primary air branch pipeline, the recycling secondary air branch pipeline, the recycling denitration system branch pipeline and the reburning air layering pipeline.
Preferably, the system further comprises: cyclone, dust remover and set up the desulphurization unit in burning living beings circulating fluidized bed flue, desulphurization unit's entry pipeline connects the outlet duct of draught fan, the entry pipeline of draught fan is connected the outlet duct of dust remover, the entry pipeline of dust remover is connected cyclone's gas outlet pipeline, cyclone's entry pipeline with furnace's exhanst gas outlet is connected.
Preferably, the desulfurization device is a semi-dry desulfurization device or a wet desulfurization device, and the dust remover is a cyclone separator, a bag-type dust remover or an electric bag dust remover.
According to the technical scheme, the system can reduce the generation of NOx, improve the efficiency of the boiler, reduce the consumption of fuel, increase the peak regulation capacity of the boiler and reduce the operation cost.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram of the overall structure of a preferred embodiment of the system of the present invention;
FIG. 2 is a schematic structural view of a preferred embodiment of a secondary air supply line;
fig. 3 is a schematic perspective view of a preferred embodiment of a secondary air supply line.
Description of the reference numerals
1-hearth; 1 a-a dense phase zone; 1 b-dilute phase zone; 2-a dust removal device; 3-an air preheater; 4-a draught fan; 5-a chimney; 6-recirculation fan; 7-a dust remover; 8-a primary air fan; 9-reburning air blower; 10 a-first regulating valve; 10 b-a second regulating valve; 10 c-a third regulating valve; 10 d-a fourth regulating valve; 10 e-a fifth regulating valve; 10 f-sixth regulating valve; 11-recirculating primary air distribution pipes; 12-recirculating secondary air distribution pipes; 12 a-main line; 12-b branch pipelines; 12 c-a first U-shaped pipe; 12 d-a second U-shaped pipeline; 12 e-a first air supply duct; 12 f-a second air supply pipe; 13-reburning the air stratified pipeline; 14-a denitrification unit; 15-a recirculating main conduit; 16-a reburning air delivery duct; 17-a fluidizing air chamber; 18-a recycling denitration system branch pipeline; 19-a filter; 20-electrically adjusting the baffle; 21-a temperature sensor; 22-a pressure sensor; 23-a wind gauge; 24-primary air duct.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
In the present invention, unless otherwise specified, directional words included in terms such as "upper, lower, left, right, front, rear, inner, and outer" and the like merely represent the directions of the terms in a normal use state or are colloquially known by those skilled in the art, and should not be construed as limiting the terms.
Referring to fig. 1, a system for reducing nitrogen oxides in a circulating fluidized bed combusting biomass is shown, the system comprising: a flue gas recirculation system and a flue gas reburning system; wherein the flue gas recirculation system comprises: the recirculation main pipeline 15 is communicated with a flue gas outlet main pipeline of the boiler, and is used for leading out low-oxygen and low-temperature flue gas in the flue gas outlet main pipeline; one end of the recirculation primary air distribution pipeline 11 is communicated with the recirculation main pipeline 15, and the other end of the recirculation primary air distribution pipeline 11 is connected with the outlet air preheater end of a primary air pipeline 24 and then communicated with the inlet of a primary fluidizing air chamber 17 at the bottom of the hearth 1; one end of the recirculation secondary air branch pipeline 12 is communicated with the recirculation main pipeline 15, and the other end of the recirculation secondary air branch pipeline 12 is communicated with a secondary air inlet in the middle of the hearth 1; one end of the recirculation denitration system branch pipeline 18 is communicated with the recirculation main pipeline 15, and the other end of the recirculation denitration system branch pipeline 18 is communicated with the denitrification device 14; the primary air pipeline 24 is communicated with the recirculation primary air branch pipeline 11 after passing through the air preheater 3; the flue gas reburning system comprises: the reburning air conveying pipeline 16 and the reburning air layering pipeline 13 are sequentially communicated with a reburning air inlet at the upper part of the hearth 1 through the air preheater 3 and the reburning air layering pipeline 13 by the reburning air conveying pipeline 16.
Through the implementation of the technical scheme, the system is externally connected with a recirculation main pipeline 15 on a main pipeline of a flue gas outlet of a boiler, the recirculated main pipeline enters an air preheater 3 and then is shunted to a recirculation primary air branch pipeline 11 and a recirculation secondary air branch pipeline 12 to form a primary loop and a secondary loop, in addition, the reburning air passes through a reburning air conveying pipeline 16, passes through the air preheater 3 and then enters a hearth 1 through a reburning air layering pipeline 13, the primary air, the secondary air and the reburning air can be adjusted through air volume, the generation amount of NOx is reduced, and the active collaborative NO removal of the compound secondary air staged combustion and the volatile component reburning is realizedXThe technology integration of the utility model can reduce the NOx emission of the biomass-fired circulating fluidized bed boiler, and the concentration of carbon monoxide in the hearth 1 can be reduced by configuring reburning air, thereby improving the efficiency of the boiler, reducing the fuel consumption, increasing the peak regulation capacity of the boiler and reducing the operation cost.
The document shows that the content of volatile components in the biomass fuel is high, the conversion rate of fuel nitrogen into nitrogen oxides is high, the nitrogen oxides are mainly generated in a concentrated manner in transition regions of a dense-phase region 1a, the dense-phase region 1a and a dilute-phase region 1b, the generation amount of the nitrogen oxides depends on the reaction atmosphere, and the higher the content of oxygen in the air distribution is, the larger the generation amount of the nitrogen oxides is. Therefore, a recirculation fan 6 is installed on a recirculation main pipeline 15, the recirculation main pipeline 15 leads out low-oxygen and low-temperature flue gas in a flue gas outlet main pipeline, and after the low-oxygen and low-temperature flue gas is led out, firstly, in order to reduce the oxygen content of a dense-phase area 1a of a hearth 1, the low-oxygen and low-temperature flue gas is pressurized and conveyed, mixed with primary air heated by an air preheater 3 and then conveyed to an inlet of a primary fluidizing air chamber 17 at the bottom of the hearth 1, namely, the fluidizing air chamber 17 of the dense-phase area 1a enters the hearth 1; in the second aspect, in order to reduce the oxygen amount in the transition areas of the dense-phase area 1a and the dilute-phase area 1b of the furnace 1, the low-oxygen and low-temperature flue gas is pressurized and conveyed to the secondary air inlet in the middle of the furnace 1, wherein the secondary air inlet in the middle of the furnace 1 is the transition area between the dense-phase area 1a and the dilute-phase area 1b of the furnace 1; in the third aspect, the low-oxygen and low-temperature flue gas is pressurized and conveyed, and is connected with the SNCR pipeline in the denitrification device 14 through the recycling denitrification system branch pipeline 18 to serve as compressed gas of a denitrification spray gun, so that the total air volume in the hearth 1 can be reduced. In addition, a primary air blower 8 is installed on the primary air pipeline 24 and used for introducing air and properly mixing the low-oxygen and low-temperature flue gas as required. In addition, the reburning air conveying pipeline 16 is provided with a reburning air fan 9 for introducing air, and the air is pressurized by the reburning air fan 9, enters the air preheater 3 through the reburning air conveying pipeline 16 for preheating, and is sent to the upper part of the hearth 1 through the reburning air layered pipeline 13.
Because the oxygen content of the primary air and the secondary air is less, the lower part of the biomass reburning chamber 1 is in anoxic combustion, a large amount of carbon monoxide can be generated in flue gas, in order to reduce the content of the carbon monoxide in the flue gas, the system is provided with reburning air, the air enters the air preheater 3 through the reburning air conveying pipeline 16 after being pressurized by the reburning air blower 9, is preheated and then is conveyed to the upper part of the chamber 1 through the reburning air layering pipeline 13, the carbon monoxide in the flue gas can be combusted by using the reburning air, the consumption of fuel is reduced, the operation cost is reduced, the temperature of the upper part of the chamber 1 can be increased, and the temperature reaches the temperature window of the denitrifying agent.
In this embodiment, the recirculation fan 6 is installed on the recirculation main pipe 15, and the recirculation fan 6 is used for pressurizing and conveying the low-oxygen and low-temperature flue gas in the recirculation main pipe 15. The low-oxygen and low-temperature flue gas is pressurized and conveyed by the recirculation fan 6.
In this embodiment, the recirculation fan 6 is disposed at the rear end of the induced draft fan 4, and the front end of the induced draft fan 4 is provided with a dust collector 7; the low-oxygen low-temperature flue gas is pressurized and then dedusted through the deduster 7, so that the dedusting effect is improved, of course, a plurality of dedusters 7 can be arranged, for example, one deduster 7 is arranged on a rear end pipeline of the recirculation fan 6, so that further dedusting is facilitated; in addition, electric adjusting baffles 20 are arranged on the recirculation main pipeline 15 at the front end of the recirculation fan 6, on the recirculation primary air branch pipeline 11, on the recirculation secondary air branch pipeline 12, on the recirculation denitration system branch pipeline 18 and on the reburning air layering pipeline 13, and are used for adjusting the low-oxygen low-temperature flue gas flow rate and reducing the generation amount of NOx through the proper low-oxygen low-temperature flue gas flow rate.
In this embodiment, at least one filter 19 is disposed on the outlet pipe of the fourth electrically-operated adjusting damper 20 on the recirculation denitration system branch pipe 18. The low-oxygen and low-temperature flue gas in the branch pipeline 18 of the recirculation denitration system is filtered by arranging the filter 19, and the filter 19 can be arranged in a plurality of or only one according to the requirement.
In this embodiment, a first regulating valve 10a is provided on an inlet pipeline of the main recirculation pipeline 15, a second regulating valve 10b is provided on the reburning air layered pipeline 13, a third regulating valve 10c is provided on the secondary recirculation air layered pipeline 12, a fourth regulating valve 10d is provided on the primary recirculation air layered pipeline 11, a fifth regulating valve 10e is provided on an outlet pipeline of the main recirculation pipeline 15, and a sixth regulating valve 10f is provided on the recirculation denitration system layered pipeline 18. The first regulating valve 10a, the second regulating valve 10b, the third regulating valve 10c, the fourth regulating valve 10d, the fifth regulating valve 10e and the sixth regulating valve 10f are arranged for isolating the low-oxygen and low-temperature flue gas at corresponding positions so as to overhaul the flue gas recirculation system.
In this embodiment, as shown in fig. 2-3, the secondary air inlet is provided with a secondary air supply line; the secondary air supply pipeline comprises: a main pipeline 12a communicated with the recirculation secondary air distribution pipeline 12, and a branch pipeline 12b communicated with and arranged at one side of the main pipeline 12 a; a first U-shaped pipeline 12c bypassing the front side of the hearth 1 is communicated between the main pipeline 12a and the branch pipeline 12b, and a second U-shaped pipeline 12d bypassing the rear side of the hearth 1 is communicated between the branch pipeline 12b and the branch pipeline 12 b; a plurality of first air supply pipes 12e extending into the hearth 1 from the front side of the hearth 1 are arranged on the first U-shaped pipeline 12c, and a plurality of second air supply pipes 12f extending into the hearth 1 from the rear side of the hearth 1 are arranged on the second U-shaped pipeline 12 d.
Through the implementation of the technical scheme, the number of the secondary air nozzles is increased, so that the reduction of the NOx emission concentration is facilitated, the position of the secondary air port is improved, the downward inclination angle of the secondary air port is reduced, the secondary air is delayed from entering, the retention time of flue gas in a reduction zone is prolonged, and the reduction of the NOx emission concentration is facilitated. A plurality of first U-shaped pipelines 12c and a plurality of second U-shaped pipelines 12d may be respectively provided, and each first U-shaped pipeline 12c or each second U-shaped pipeline 12d is provided with a plurality of first air supply pipes 12e and a plurality of second air supply pipes 12 f.
In this embodiment, a temperature sensor 21, a pressure sensor 22, and an air gauge 23 are provided on the recirculation primary air branch duct 11, the recirculation secondary air branch duct 12, the recirculation denitration system branch duct 18, and the recirculation air stratification duct 13, and a temperature sensor 21 and a pressure sensor 22 are provided on the recirculation main duct 15. Through the arrangement, the temperature and the pressure of the corresponding positions, and the temperature, the pressure and the air volume can be monitored, and through the monitoring of the data, the data support for adjusting the low-oxygen and low-temperature smoke gas flow through the electric adjusting baffle 20 is provided.
In this embodiment, stainless steel expansion joints are disposed on the recirculation primary air branch pipe 11, the recirculation secondary air branch pipe 12, the recirculation denitration system branch pipe 18, and the reburning air layering pipe 13.
In this embodiment, the system further comprises: cyclone 2, dust remover 7 and set up the desulphurization unit in burning living beings circulating fluidized bed flue, desulphurization unit's entry pipeline connects the outlet duct of draught fan 4, the entry pipeline of draught fan 4 connects the outlet duct of dust remover 7, the entry pipeline of dust remover 7 connects the gas outlet pipeline of cyclone 2, cyclone's entry pipeline with the exhanst gas outlet of furnace 1 connects.
The flue gas that the exhanst gas outlet of furnace 1 discharges passes through denitrification facility 14 earlier, and the fuel and the bed material that flow along with the flue gas in the furnace are sent back to furnace through cyclone 2 again, and remaining flue gas is introduced to chimney 5 through draught fan 4 after 7 dust removals of dust remover, is provided with the flue in the chimney 5, is provided with desulphurization unit in the flue. And the access position of the main recirculation pipeline 15 is between the inlet pipeline of the desulfurization device and the outlet pipeline of the induced draft fan 4, and low-oxygen and low-temperature flue gas is introduced through the position.
In this embodiment, the desulfurization apparatus is a semi-dry desulfurization apparatus or a wet desulfurization apparatus.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims (10)

1. A system for reducing nitrogen oxides in a circulating fluidized bed combusting biomass, the system comprising: a flue gas recirculation system and a flue gas reburning system; wherein,
the flue gas recirculation system comprises:
the main recirculating pipeline (15), the main recirculating pipeline (15) is communicated with the main flue gas outlet pipeline of the boiler and is used for leading out the low-oxygen and low-temperature flue gas in the main flue gas outlet pipeline;
the recycling primary air distribution pipeline (11), one end of the recycling primary air distribution pipeline (11) is communicated with the recycling main pipeline (15), and the other end of the recycling primary air distribution pipeline is connected with an air outlet preheater end of a primary air pipeline (24) and then communicated with an inlet of a primary fluidizing air chamber (17) at the bottom of the hearth (1);
one end of the recirculation secondary air branch pipeline (12) is communicated with the recirculation main pipeline (15), and the other end of the recirculation secondary air branch pipeline (12) is communicated with a secondary air inlet in the middle of the hearth (1);
one end of the recycling denitration system branch pipeline (18) is communicated with the recycling main pipeline (15), and the other end of the recycling denitration system branch pipeline (18) is communicated with the denitrification device (14);
the primary air pipeline (24) is communicated with the recirculation primary air branch pipeline (11) after passing through the air preheater (3);
the flue gas reburning system comprises:
the reburning air conveying pipeline (16) and the reburning air layering pipeline (13) are sequentially communicated with a reburning air inlet at the upper part of the hearth (1) after passing through the air preheater (3) and the reburning air layering pipeline (13).
2. The system for reducing nitrogen oxides in a circulating fluidized bed combusting biomass according to claim 1, wherein the main recirculating pipeline (15) is provided with a recirculating fan (6), and the recirculating fan (6) is used for pressurizing and conveying low-oxygen and low-temperature flue gas in the main recirculating pipeline (15).
3. The system for reducing the nitrogen oxides in the circulating fluidized bed burning biomass according to claim 2, wherein the recirculation fan (6) is arranged at the rear end of the induced draft fan (4);
the recycling main pipeline (15) is located at the front end of the recycling fan (6), the recycling primary air branch pipeline (11), the recycling secondary air branch pipeline (12), the recycling denitration system branch pipeline (18) and the reburning air layering pipeline (13) are all provided with electric adjusting baffles (20).
4. The system for reducing nitrogen oxides in a circulating fluidized bed burning biomass according to claim 3, wherein at least one filter (19) is arranged on the outlet pipeline of the fourth electrically-operated adjusting baffle (20) on the recirculating denitration system branch pipeline (18).
5. The system for reducing the nitrogen oxides in the biomass-fired circulating fluidized bed according to any one of claims 1 to 4, wherein a first regulating valve (10a) is arranged on an inlet pipeline of the main recirculating pipeline (15), a second regulating valve (10b) is arranged on the reburning air layering pipeline (13), a third regulating valve (10c) is arranged on the secondary recirculating air layering pipeline (12), a fourth regulating valve (10d) is arranged on the primary recirculating air layering pipeline (11), a fifth regulating valve (10e) is arranged on an outlet pipeline of the main recirculating pipeline (15), and a sixth regulating valve (10f) is arranged on the recirculating denitration system layering pipeline (18).
6. The system for reducing nitrogen oxides in a circulating fluidized bed combusting biomass according to claim 1, wherein the secondary air inlet is provided with a secondary air supply pipeline;
the secondary air supply pipeline comprises: a main pipeline (12a) communicated with the recirculation secondary air distribution pipeline (12), and a branch pipeline (12b) communicated with one side of the main pipeline (12 a);
a first U-shaped pipeline (12c) bypassing the front side of the hearth (1) is communicated and arranged between the main pipeline (12a) and the branch pipeline (12b), and a second U-shaped pipeline (12d) bypassing the rear side of the hearth (1) is communicated and arranged between the branch pipeline (12b) and the branch pipeline (12 b);
a plurality of first air supply pipes (12e) extending into the hearth (1) from the front side of the hearth (1) are arranged on the first U-shaped pipeline (12c), and a plurality of second air supply pipes (12f) extending into the hearth (1) from the rear side of the hearth (1) are arranged on the second U-shaped pipeline (12 d).
7. The system for reducing the nitrogen oxides in the biomass-fired circulating fluidized bed according to claim 1, wherein a temperature sensor (21), a pressure sensor (22) and an air gauge (23) are arranged on the recirculating primary air branch pipeline (11), the recirculating secondary air branch pipeline (12), the recirculating denitration system branch pipeline (18) and the recirculating air layering pipeline (13), and a temperature sensor (21) and a pressure sensor (22) are arranged on the recirculating main pipeline (15).
8. The system for reducing the nitrogen oxides in the biomass-fired circulating fluidized bed according to claim 1, wherein stainless steel expansion joints are arranged on the recirculating primary air branch pipeline (11), the recirculating secondary air branch pipeline (12), the recirculating denitration system branch pipeline (18) and the reburning air layering pipeline (13).
9. The system for reducing nitrogen oxides in a circulating fluidized bed combusting biomass of claim 1, further comprising: cyclone (2), dust remover (7) and set up the desulphurization unit in burning biomass circulating fluidized bed flue, desulphurization unit's entry pipe connection draught fan (4) outlet conduit, the entry pipe connection of draught fan (4) the outlet conduit of dust remover (7), the entry pipe connection of dust remover (7) the gas outlet pipeline of cyclone (2), the entry pipeline of cyclone (2) with the exhanst gas outlet of furnace (1) is connected.
10. The system for reducing the nitrogen oxides in the circulating fluidized bed of the fuel biomass according to claim 9, wherein the desulfurization device is a semi-dry desulfurization device or a wet desulfurization device, and the dust remover (7) is a cyclone separator, a bag-type dust remover or an electric bag dust remover.
CN202210278691.6A 2022-03-21 2022-03-21 System for reducing nitrogen oxides of biomass-fired circulating fluidized bed Pending CN114543081A (en)

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Application Number Priority Date Filing Date Title
CN202210278691.6A CN114543081A (en) 2022-03-21 2022-03-21 System for reducing nitrogen oxides of biomass-fired circulating fluidized bed

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210278691.6A CN114543081A (en) 2022-03-21 2022-03-21 System for reducing nitrogen oxides of biomass-fired circulating fluidized bed

Publications (1)

Publication Number Publication Date
CN114543081A true CN114543081A (en) 2022-05-27

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Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
CN (1) CN114543081A (en)

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