CN110252051B - Method for dedusting, desulfurizing and denitrating boiler flue gas and removing dioxin - Google Patents

Method for dedusting, desulfurizing and denitrating boiler flue gas and removing dioxin Download PDF

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Publication number
CN110252051B
CN110252051B CN201910445960.1A CN201910445960A CN110252051B CN 110252051 B CN110252051 B CN 110252051B CN 201910445960 A CN201910445960 A CN 201910445960A CN 110252051 B CN110252051 B CN 110252051B
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flue gas
basalt fiber
filter cartridge
fiber filter
shell
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CN110252051A (en
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董统玺
于宪河
高长龙
于长海
王明仁
陈亮
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Shandong Zhongqi Environmental Protection Equipment Manufacturing Co ltd
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Shandong Zhongqi Environmental Protection Equipment Manufacturing Co ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D46/00Filters, i.e. particle separators or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2411Filter cartridges
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/74General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86Catalytic processes
    • B01D53/8621Removing nitrogen compounds
    • B01D53/8625Nitrogen oxides
    • B01D53/8628Processes characterised by a specific catalyst
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/74General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86Catalytic processes
    • B01D53/8621Removing nitrogen compounds
    • B01D53/8625Nitrogen oxides
    • B01D53/8631Processes characterised by a specific device
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/74General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86Catalytic processes
    • B01D53/8659Removing halogens or halogen compounds
    • B01D53/8662Organic halogen compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/74General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86Catalytic processes
    • B01D53/88Handling or mounting catalysts
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2251/00Reactants
    • B01D2251/60Inorganic bases or salts
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2257/00Components to be removed
    • B01D2257/40Nitrogen compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2257/00Components to be removed
    • B01D2257/60Heavy metals or heavy metal compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2257/00Components to be removed
    • B01D2257/60Heavy metals or heavy metal compounds
    • B01D2257/602Mercury or mercury compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2258/00Sources of waste gases
    • B01D2258/02Other waste gases
    • B01D2258/0283Flue gases
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y02A50/2351Atmospheric particulate matter [PM], e.g. carbon smoke microparticles, smog, aerosol particles, dust

Abstract

The invention discloses a method for dedusting, desulfurizing, denitrating and removing dioxin from boiler flue gas, which comprises the following steps: leading out flue gas with the temperature of 250-350 ℃ from a boiler, spraying 600-700-mesh bicarbonate into the flue gas, and reacting; adding a reducing agent into the reacted flue gas, and then feeding the flue gas into a denitration composite dust removal device for denitration, dioxin removal and dust removal; the denitration composite dust removal device comprises a shell, a partition plate and a plurality of basalt fiber filter cartridges, wherein the partition plate is arranged on the cross section of the shell and divides the shell into a first chamber and a second chamber; each basalt fiber filter cartridge is a hollow pipe body, and a catalyst is bonded on the basalt fiber cotton; each basalt fiber filter cartridge is installed on the partition plate and integrally located in the first cavity, and an opening of each basalt fiber filter cartridge is communicated with the second cavity.

Description

Method for dedusting, desulfurizing and denitrating boiler flue gas and removing dioxin
Technical Field
The invention belongs to the technical field of flue gas dust removal, desulfurization and denitrification, and particularly relates to a method for removing dust, desulfurization and denitrification and removing dioxin from boiler flue gas.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
China is a big agricultural country, has rich biomass raw materials and can be used for the power generation industry in large quantity; the discharge amount of nitrogen and sulfur oxides in the flue gas is large, but the treatment force is not enough, so that the serious ecological problem is caused. Therefore, how to treat nitrogen and sulfur oxides in flue gas and reduce the harm to the environment is urgent.
The traditional desulfurization, denitrification and dust removal modes are mostly wet flue gas process/dry flue gas process and cloth bag dust removal process. The wet process product is liquid or sludge, is difficult to treat, has serious equipment corrosivity, requires reheating of the flue gas after washing, and has high energy consumption, large occupied area and high investment and operation cost. Calcium sulfite and calcium sulfate generated after sulfur dioxide is absorbed by adopting a calcium-based desulfurizer are easy to form scaling and blocking phenomena in a desulfurizing tower and a pipeline due to low solubility. The dry process has low desulfurization efficiency, low utilization rate of the absorbent, serious phenomena of abrasion and scaling, high difficulty in equipment maintenance, low stability and reliability of equipment operation and short service life, and limits the application of the method.
The simultaneous flue gas desulfurization and denitration technology mainly comprises three types, wherein the first type is a combined technology of flue gas desulfurization and flue gas denitration; the second type is the simultaneous removal of SO by using an adsorbentXAnd NOX(ii) a And the third type is to modify the existing flue gas desulfurization system (such as adding a denitration agent into a desulfurization solution) and add a denitration function.
Adding a metal catalyst by a wet method: over 90 percent of SO can be removed by wet desulphurization2However, since NO has a low solubility in water, it has little effect on NO removal. Some metal catalysts, such as Fe (11) -EDTA, etc., can react rapidly with dissolved NOx, and have the effect of promoting NOx absorption. A company in America adopts 6 percent of magnesia reinforced lime as a desulfurizer, and adds Fe (II) -EDTA into desulfurization solution to carry out pilot-scale research of simultaneous desulfurization and denitrification, thereby realizing the denitrification rate of more than 60 percent and the desulfurization rate of about 99 percent. The disadvantage of wet FGD metal catalyst adding processThe main points are that the catalyst is lost in the reaction, the recycling of the catalyst is difficult, and the operation cost is very high.
The bag-type dust collector is a dry dust filter. It is suitable for trapping fine, dry, non-fibrous dust. The filter bag is made of woven filter cloth or non-woven felt, the dust-containing gas is filtered by the filtering action of the fiber fabric, after the dust-containing gas enters the bag type dust collector, dust with large particles and large specific gravity falls into the dust hopper due to the sedimentation of the gravity, and when the gas containing fine dust passes through the filter material, the dust is blocked, so that the gas is purified. However, the inventors have found that bag-type dust collectors have many disadvantages, such as: firstly, in the daily operation of the bag type dust collector, the normal operation condition and the working performance of equipment are influenced due to certain changes of the operation condition or certain faults, and the operation stability is poor; secondly, the device cannot adapt to the high-temperature and acid-base corrosion environment of the biomass power plant; and combustion, explosion and fire accidents easily occur to the bag type dust collector.
In addition, for certain flue gas containing a large amount of dioxin, such as flue gas of a garbage boiler, the method for removing the dioxin is generally to use an activated carbon adsorption bag-type dust remover, but the activated carbon adsorption has the following disadvantages: 1) the activated carbon needs to be provided with an expensive injection device, and the removal efficiency is influenced by the fluctuation of feeding work; 2) the active carbon adsorbs dioxin, and only transfers the dioxin into fly ash, so that the total amount is not reduced; 3) the adsorption efficiency of the active carbon has close relation with factors such as the specific surface area of the active carbon, the mixing degree of the flue gas and the like, and the process is difficult to control stably and completely; 4) the fly ash contains dioxin, and the dioxin needs to be sent to a dangerous waste treatment plant for retreatment to prevent the dioxin from escaping again; 5) because of the existence of carbon, the hidden danger of fire hazard generated naturally in the dust collector is increased; 6) the active carbon has the adsorption function but not the decomposition function, and the working personnel are in the dangerous environment.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention aims to provide a method for dedusting, desulfurizing and denitrating boiler flue gas and removing dioxin. The method can effectively remove pollutants such as dust particles, sulfides, nitric oxides, dioxin and the like in the flue gas, and can be widely applied to biomass boilers, garbage boilers, coking furnaces, hazardous waste incinerators and the like.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a method for dedusting, desulfurizing, denitrating and removing dioxin from boiler flue gas comprises the following steps:
leading out flue gas with the temperature of 250-350 ℃ from a boiler, spraying 600-700-mesh bicarbonate into the flue gas, and reacting;
adding a reducing agent into the reacted flue gas, and then feeding the flue gas into a denitration composite dust removal device for denitration, dioxin removal and dust removal;
the denitration composite dust removal device comprises a shell, a partition plate and a plurality of basalt fiber filter cartridges, wherein the partition plate is arranged on the cross section of the shell and divides the shell into a first chamber and a second chamber;
each basalt fiber filter cartridge is a hollow pipe body, the wall of the pipe body is of a filter cartridge structure formed by binding basalt fiber cotton, a catalyst is bound on the basalt fiber cotton, one end of the basalt fiber cotton is sealed, and the other end of the basalt fiber cotton is open;
each basalt fiber filter cartridge is mounted on the partition plate and integrally positioned in the first cavity, and an opening of each basalt fiber filter cartridge is communicated with the second cavity;
the flue gas added with the reducing agent enters from the flue gas inlet, flows into the second chamber after being filtered and subjected to catalytic reaction, and flows out from the flue gas outlet.
600-700 mesh particle size is about 20-30 μm, the superfine powder sodium bicarbonate particles have huge specific surface area, and are quickly decomposed into fresh sodium carbonate under heat in reasonable smoke temperature, the sodium carbonate generated after decomposition has high surface activity and strong capability of reacting with acid substances, and the sodium carbonate quickly reacts with the acid substances in the smoke such as SO2、SO3HF, HCl, etc. Such as sodium sulfite and sodium sulfate, by reacting with SOx in the flue gas. Control system desulfurization by regulating additionThe amount of the agent (sodium bicarbonate) is used for controlling the emission value of the flue gas desulfurization. The reaction process of desulfurization takes place in two links, firstly the contact process of desulfurizer and flue gas in the desulfurization reactor, secondly be stained with the desulfurizer that attaches on the basalt fiber cartridge filter outside of denitration composite dust collector behind and not completely react and continue the contact reaction with the flue gas, reduce the concentration of sulfur dioxide in the flue gas, reduce ABS (ammonium bisulfate)'s production simultaneously.
After a reducing agent is added into the desulfurized flue gas, the flue gas enters the denitration composite dust removal device, in the process that the flue gas flows from the first chamber to the second chamber through the basalt fiber filter cartridge, dust in the flue gas is filtered by the basalt fiber filter cartridge, the filtered flue gas enters the basalt fiber filter cartridge, contacts with a catalyst on the wall of the basalt fiber filter cartridge, and is subjected to catalytic reaction, denitration and dioxin removal. The dust forms a dust layer with a certain thickness on the outer wall of the basalt fiber filter cylinder, and can poison heavy metal arsenic (As), selenium (Se) and mercury (Hg) in the smoke and alkali metal Na2O、K2And O and the like are intercepted, so that the toxic action of the substances on the catalyst is reduced, the service life of the catalyst is prolonged, and the catalyst can keep high-efficiency activity for a long time.
The basalt fiber filter cartridge can also intercept the bicarbonate desulfurizer, and continuously react with sulfur dioxide in the flue gas to improve the removal efficiency of the sulfur dioxide.
The denitration principle is as follows:
4NO+4NH3+O2→4N2+6H2o; or
4NO+2(NH2)2CO+O2→4N2+4H2O+2CO2
The dioxin removal principle is as follows:
C12HnCl8-nO2+(9+0.5n)O2→(n-4)H2O+12CO2+(8-n)HCl。
in some embodiments, the bicarbonate is sodium bicarbonate or slaked lime.
In some embodiments, the quality of bicarbonate added in each cubic meter of flue gas is adjusted according to different components of the flue gas, so as to ensure the thorough removal of sulfur dioxide in the flue gas.
In some embodiments, the reducing agent is ammonia or urea, and the catalyst in the catalyst layer is a vanadium-titanium-tungsten based catalyst or a vanadium-titanium based catalyst.
Furthermore, the mass of the reducing agent added in each cubic meter of flue gas is adjusted according to different components of the flue gas.
In some embodiments, the basalt fiber filter cylinder has an outer diameter of 150mm-152mm, an inner diameter of 104mm-110mm, an outer diameter of 190mm-196mm of a flange face, a height of 30mm +/-2 mm of the flange face, a length of 2.95m-3m and a weight of 12.5 +/-1 Kg; the filtration area is more than or equal to 1.4m2Density of 0.4g/dm3(ii) a The diameter of the basalt fiber is 2-3 mm.
In some embodiments, the basalt fiber filter cartridge is prepared by a method comprising:
chopping basalt fibers, and carrying out ball milling until the length-diameter ratio of the fibers is 30-100;
mixing basalt fibers with an inorganic binder to prepare uniform slurry;
injecting the material into a die, carrying out suction filtration molding, drying, and loading a catalyst to obtain the basalt fiber filter cartridge.
Further, the inorganic binder is silica sol or aluminum dihydrogen phosphate. These two inorganic binders do not cause catalyst poisoning.
In some embodiments, a blowback nozzle is arranged in each basalt fiber filter cartridge and is connected with a compressed air source.
Compressed air source provides compressed air for the blowback shower nozzle, utilizes compressed air to carry out the blowback to the basalt fiber cartridge filter that the deposit has the dust layer, can blow off filterable dust to improve the filter effect to the flue gas, guarantee the smooth and easy circulation of flue gas.
Furthermore, the back-blowing nozzle is arranged along the axial direction of the basalt fiber filter cartridge, and a plurality of groups of nozzles are arranged along the axial direction of the back-blowing nozzle.
The plurality of groups of nozzles are arranged, so that the positions of the basalt fiber filter cartridge can be subjected to back flushing cleaning, and the dust layer deposited on the basalt fiber filter cartridge is cleaned through back flushing.
Furthermore, the pressure of the back blowing air is 0.5-0.7MPa, and the back blowing air is subjected to pulse blowing.
In some embodiments, the bottom of the shell is of an inverted cone structure, and the lowest part of the shell is provided with an ash discharge port.
The dust blown down by back blowing falls into the inverted cone structure and is smoothly discharged through the dust discharge port.
In some embodiments, a baffle is provided at the rear of the boiler, and the economizer and the air preheater are provided downstream of the baffle.
Further, the clean flue gas discharged from the second chamber of the shell is conveyed to the downstream of the partition plate again, flows through the coal economizer and the air preheater and is discharged from a chimney.
Because the temperature of the flue gas after desulfurization and denitration is still very high, waste heat recovery is carried out through the economizer and the air preheater, and the waste of heat can be effectively prevented. Clean flue gas is sent back to the economizer, and the waste heat recovery heating surface at the tail part does not deposit dust or corrode, so that the working condition of the heating surface is thoroughly improved, and the heat exchange effect is improved. Greatly reduces the increase of the power consumption of the induced draft fan caused by the increase of the ash blocking resistance, and greatly reduces the times of blowing out and cleaning ash of the boiler.
The invention has the beneficial effects that:
1. biomass boiler flue gas is matched with a basalt fiber filter cartridge for dry desulfurization and high-temperature passing through catalyst, NOXThe reduction rate reaches more than 95 percent, and the desulfurization efficiency is improved; emission parameters: dust is less than or equal to 10mg/m3The minimum can reach 5mg/m3;NOx≤50mg/m3; SO2<35mg/m3Dust removal, desulfurization, denitration, dioxin removal and ultra-clean emission of flue gas are realized.
2. The problem of poisoning failure of the flue gas SCR denitration catalyst is solved, the catalyst is inert to all chemicals, and chemical poisoning can be prevented; the method makes it possible that flue gas of biomass boilers, garbage boilers, other industrial kilns and the like cannot realize SCR conventional denitration.
3. The catalyst is evenly distributed on the filter cylinder, the contact reaction area of the catalyst and the denitration agent (ammonia water or urea solution) and the flue gas is large, the reaction time is long, the ammonia escape is less, and the denitration efficiency is greatly improved.
4. The basalt fiber filter cartridge has the advantages of high temperature resistance, corrosion resistance, long service life, low resistance loss, high dust removal efficiency and the like; based on the mechanism of surface filtration, dust-containing gas with strong adhesion is treated, and blockage is not easy to generate.
5. The basalt fiber filter cartridge is matched with dry desulfurization (sodium bicarbonate or calcium hydroxide), and a filter cake layer can be formed on the surface of the filter cartridge by a desulfurizing agent, so that the desulfurization efficiency is improved;
after the flue gas at the temperature of 6.250-350 ℃ is dedusted, desulfurized and denitrated, the waste heat recovery heating surface at the tail part is free of dust accumulation and corrosion, the working condition of the heating surface is thoroughly improved, and the heat exchange effect is improved.
7. The low-temperature heating surface is added to the boiler, the exhaust gas temperature can be reduced by 50-70 ℃, and the thermal efficiency of the boiler is improved by 3-5%.
8. The heated surface of the tail part of the boiler after the high-temperature composite filter cartridge is free from dust accumulation and corrosion, the power consumption increase of a draught fan caused by the increase of the dust blocking resistance is greatly reduced, and the boiler shutdown and ash removal times are greatly reduced.
9. The basalt fiber filter cartridge can also remove dioxin in flue gas.
10. The basalt fiber filter cartridge is matched with dry desulphurization (sodium bicarbonate or calcium hydroxide), and water does not participate in the reaction, so that smoke plume generated by wet desulphurization is avoided.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a schematic structural diagram of a denitration composite dust removing apparatus according to an embodiment of the present invention;
fig. 2 is a schematic view illustrating the basalt fiber filter cartridge filtering exhaust gas according to an embodiment of the present invention.
In the figure: 1-a flue gas outlet, 2-a shell, 3-a main pipe, 4-a partition plate, 5-a pipe body wall, 6-a back-blowing spray head and 7-a flue gas inlet.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example 1
This example was carried out in a biomass power generation boiler, and the main raw material was biomass, and the exhaust gas mainly contained smoke, sulfur oxides, nitrogen oxides, and the like. According to the biomass test report, the sulfur content of the biomass used in the embodiment is 0.32%, and the ash content is 7.11%. According to the calculation: SO (SO)2The yield was 458.88t/a (129.6kg/h), the yield was 466.4mg/m3(ii) a In order to meet the standard limit requirements of the emission standard of atmospheric pollutants for boilers, the alkali consumption for desulfurization is 287t/a, and the lime amount is 202 t/a. According to the biomass test report, the nitrogen content of the biomass used in the project is 0.22%. According to calculation, NOXThe yield was 281.06t/a (79.4kg/h), the yield was 285.7mg/m3. In order to meet the standard limit requirement of the emission Standard of atmospheric pollutants for boilers, the embodiment needs to reduce the amount of nitrogen oxide in flue gas by more than 90 percent and control NOx to be less than or equal to 50mg/Nm3
The boiler economizer is directly improved, and heated flue gas is led out from the economizer part, and the flue gas temperature is 350 ℃.
The denitration composite dedusting device is shown in a structural schematic diagram in fig. 1 and comprises a shell 2, a partition plate 4 and a plurality of basalt fiber filter cartridges, wherein the partition plate 4 is arranged on the cross section of the shell 2 and divides the shell 2 into a first chamber and a second chamber, a flue gas inlet 7 is arranged on the side wall of the shell 2 of the first chamber, and a flue gas outlet 1 is arranged on the side wall of the shell of the second chamber;
each basalt fiber filter cartridge is a hollow pipe body, the wall of the pipe body is of a filter cartridge structure formed by binding basalt fiber cotton, a catalyst is bound on the basalt fiber cotton, one end of the basalt fiber cotton is sealed, and the other end of the basalt fiber cotton is open;
each basalt fiber filter cartridge is arranged on the partition plate 4 and integrally positioned in the first chamber, and an opening of each basalt fiber filter cartridge is communicated with the second chamber;
the basalt fiber filter cartridge has the outer diameter of 150mm-152mm, the inner diameter of 104mm-110mm, the outer diameter of a flange surface of 190mm-196mm, the height of the flange surface of 30mm +/-2 mm, the length of 2.95m-3m and the weight of 12.5 +/-1 Kg; the filtration area is more than or equal to 1.4m2Density of 0.4g/dm3(ii) a The diameter of the basalt fiber is 2-3 mm.
A back-blowing nozzle 6 is arranged in each basalt fiber filter cartridge, and the back-blowing nozzle 6 is connected with a compressed air source through a header pipe 3.
The preparation process of the basalt fiber filter cartridge comprises the following steps:
(1) treating basalt fiber cotton: firstly, chopping basalt fibers, ball-milling the chopped basalt fibers in a ball-milling tank for a certain time, and controlling the length-diameter ratio of the fibers to be 30-100 through the time. In order to better improve the bonding of the fibers to the binder and catalyst, a certain amount of surface modifier is generally added.
(2) Selection of inorganic adhesive: in consideration of the possibility that sodium ions in water glass may poison the catalyst and reduce the catalyst effect, the bonding is performed using an alkali-free inorganic binder such as silica sol or aluminum dihydrogen phosphate. According to relevant theoretical research and practical experiments, the content of the bonding agent such as silica sol is generally not higher than 1%.
(3) Mixing the ground basalt short fiber and an inorganic binder under a high-speed stirring state to prepare uniform slurry, injecting the slurry into a die for rapid suction filtration molding after the slurry is uniformly dispersed, removing moisture, demolding and drying a wet blank formed by suction filtration molding, and performing low-temperature treatment to obtain the basalt short fiber composite filter cartridge.
(4) Compounding a vanadium-titanium catalyst: the process of the basalt fiber pipe containing the vanadium-titanium catalyst is basically the same as that of the common basalt fiber pipe, and only the vanadium-titanium catalyst is uniformly added in a wet process and then stirred at a high speed, wherein the content of the catalyst is related to the process.
The inlet and the outlet of the flue gas system are both provided with a flue gas online continuous detection system, and the inlet and the outlet are respectively monitored: SO (SO)2、O2Temperature, pressure, flow, dust. The desulfurization reactor is designed with a high-efficiency device for spraying and uniformly distributing sodium-based dry powder, the temperature of flue gas discharged by a boiler is adjusted by hot flue gas, the flue gas temperature is 320 ℃, and the flue gas flow is 41.3 ten thousand meters3H, feeding into a desulfurization reactor, and spraying dry sodium bicarbonate (NaHCO)3Baking soda) ultrafine particle (ground into 20-30 μm, 600-mesh and 700-mesh) powder, wherein the baking soda particle of the ultrafine powder has huge specific surface area, is rapidly decomposed into fresh sodium carbonate under heat at reasonable flue gas temperature, and the sodium carbonate generated after decomposition has high surface activity and strong capability of reacting with acidic substances such as SO in the flue gas rapidly2、SO3HF, HCl, etc. Such as sodium sulfite and sodium sulfate, by reacting with SOx in the flue gas. The control system controls the emission value of flue gas desulfurization by adjusting the amount of the added desulfurizing agent (sodium bicarbonate).
As shown in fig. 2, after ammonia gas is added to the desulfurized flue gas, the flue gas flows into the denitration composite dust removal device, flows into the denitration composite dust removal device from a flue gas inlet, is filtered by the tube body wall 5, flows through the catalyst layer 6, and is subjected to catalytic reaction in the catalyst layer 6 to remove nitrogen oxides and dioxin in the flue gas. Then flows into the second chamber and out through the flue gas outlet 1.
After the device runs for a period of time, the compressed air source provides pulse backflushing air flow to backflush the basalt fiber filter cartridge, and the pressure of the compressed air is 0.7 MPa.
The flue gas after desulfurization and denitrification reaches the standard.
Example 2
The inlet and the outlet of the flue gas system are both provided with a flue gas online continuous detection system, and the inlet and the outlet are respectively monitored: SO (SO)2、O2Temperature ofPressure, flow, dust. The desulfurization reactor is designed with a high-efficiency device for spraying and uniformly distributing sodium-based dry powder, the flue gas discharged from a boiler is subjected to temperature regulation by hot flue gas, the flue gas temperature is 300 ℃, and the flue gas enters the desulfurization reactor and is sprayed with dry sodium bicarbonate (NaHCO)3Baking soda) ultrafine particle (600-650 mesh) powder, the baking soda particle of the ultrafine powder has huge specific surface area, is rapidly decomposed into fresh sodium carbonate when heated at reasonable flue gas temperature, and the sodium carbonate generated after decomposition has high surface activity, has strong capability of reacting with acid substances, and rapidly reacts with the acid substances in the flue gas such as SO2、SO3HF, HCl, etc. Such as sodium sulfite and sodium sulfate, by reacting with SOx in the flue gas. The control system controls the emission value of flue gas desulfurization by adjusting the amount of the added desulfurizing agent (sodium bicarbonate).
After urea is added into the desulfurized flue gas, the flue gas flows into the denitration composite dust removal device, flows into the denitration composite dust removal device from a flue gas inlet, flows through the catalyst layer 6 after being filtered by the tube body wall 5, and is subjected to catalytic reaction in the catalyst layer 6 to remove nitrogen oxides and dioxin in the flue gas. Then flows into the second chamber and out through the flue gas outlet 1.
After the device runs for a period of time, the compressed air source provides pulse backflushing air flow to backflush the basalt fiber filter cartridge, and the pressure of the compressed air is 0.7 MPa. The treated smoke reaches the standard.
The treated flue gas returns to the tail part of the boiler again, and is discharged through a chimney after passing through the economizer and the air preheater for waste heat recovery.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (6)

1. A method for dedusting, desulfurizing, denitrating and removing dioxin from boiler flue gas is characterized by comprising the following steps: the method comprises the following steps:
leading out flue gas with the temperature of 250-350 ℃ from a boiler, spraying 600-700-mesh bicarbonate into the flue gas, and reacting;
adding a reducing agent into the reacted flue gas, and then feeding the flue gas into a denitration composite dust removal device for denitration, dioxin removal and dust removal;
the denitration composite dust removal device comprises a shell, a partition plate and a plurality of basalt fiber filter cartridges, wherein the partition plate is arranged on the cross section of the shell and divides the shell into a first chamber and a second chamber;
each basalt fiber filter cartridge is a hollow pipe body, the wall of the pipe body is of a filter cartridge structure formed by binding basalt fiber cotton, a catalyst is bound on the basalt fiber cotton, one end of the basalt fiber cotton is sealed, and the other end of the basalt fiber cotton is open;
each basalt fiber filter cartridge is mounted on the partition plate and integrally positioned in the first cavity, and an opening of each basalt fiber filter cartridge is communicated with the second cavity;
the flue gas added with the reducing agent enters from a flue gas inlet, flows into the second chamber after being filtered and subjected to catalytic reaction, and flows out from a flue gas outlet;
the bicarbonate is sodium bicarbonate;
the reducing agent is ammonia gas or urea, and the catalyst is a vanadium-titanium-tungsten catalyst or a vanadium-titanium catalyst;
and a partition plate is arranged at the tail part of the boiler, the economizer and the air preheater are arranged at the downstream of the partition plate, and the clean flue gas discharged from the second chamber of the shell is conveyed to the downstream of the partition plate again and is discharged from a chimney after flowing through the economizer and the air preheater.
2. The method of claim 1, wherein: the basalt fiber filter cartridge has an outer diameter of 150mm-152mm, an inner diameter of 104mm-110mm, and a filter area of more than or equal to 1.4m2The diameter of the basalt fiber is 2-3 mm.
3. The method of claim 1, wherein: the preparation method of the basalt fiber filter cartridge comprises the following steps:
chopping basalt fibers, and carrying out ball milling until the length-diameter ratio of the fibers is 30-100;
mixing basalt fibers with an inorganic binder to prepare uniform slurry;
and injecting the slurry into a mold, carrying out suction filtration molding, drying, and loading a catalyst to obtain the basalt fiber filter cartridge.
4. The method of claim 3, wherein: the inorganic binder is silica sol or aluminum dihydrogen phosphate.
5. The method of claim 1, wherein: a back-blowing nozzle is arranged in each basalt fiber filter cartridge and is connected with a compressed air source;
furthermore, the back-blowing nozzle is arranged along the axial direction of the basalt fiber filter cartridge, and a plurality of groups of nozzles are arranged along the axial direction of the back-blowing nozzle;
the pressure of the back blowing air is 0.5-0.7MPa, and the back blowing air is subjected to pulse blowing.
6. The method of claim 5, wherein: the bottom of the shell is of an inverted cone structure, and the bottommost part of the shell is provided with an ash discharge port.
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