CN111821856A - Industrial flue gas denitration method - Google Patents

Industrial flue gas denitration method Download PDF

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Publication number
CN111821856A
CN111821856A CN202010745037.2A CN202010745037A CN111821856A CN 111821856 A CN111821856 A CN 111821856A CN 202010745037 A CN202010745037 A CN 202010745037A CN 111821856 A CN111821856 A CN 111821856A
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flue gas
catalytic
desulfurization
reducing agent
denitration
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韩建英
李灿华
韩建平
黄献
张永柱
陈玉坡
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Hunan Cuizhi Environmental Protection Technology Co ltd
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Hunan Cuizhi Environmental Protection Technology Co ltd
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D—SEPARATION
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D50/00—Combinations of methods or devices for separating particles from gases or vapours
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
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    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/343—Heat recovery
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation 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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation 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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/75—Multi-step processes
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    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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    • B01D53/00—Separation 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
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Abstract

An industrial flue gas denitration method specifically comprises the following steps: (1) arranging a desulfurization and dust removal device on the smoke exhaust pipeline to remove more than 95wt% of dust and sulfur in the smoke; (2) adding an ammonia compound or an amine compound as a reducing agent into the flue gas treated in the step (1), and mixing the reducing agent with the flue gas; (3) arranging an injection point on a smoke exhaust pipeline or/and smoke treatment equipment, grinding the powder into micron-sized transition metal or compound thereof serving as catalytic particles, and injecting reducing agent into the injection point through a conveying deviceAnd NOXAnd mixing with the flue gas; (4) in high temperature flue gas environment, NOXAnd the molecules and the reducing agent are subjected to catalytic reduction reaction under the action of the catalytic particles to generate nitrogen and water, so that the reduction denitration reaction is realized. The invention has the advantages of low investment, low operation cost, no waste water, no blockage, no poisoning, high reliability and the like.

Description

Industrial flue gas denitration method
Technical Field
The invention relates to the field of atmospheric pollution treatment, in particular to an industrial flue gas denitration method.
Background
The problem of nitrogen oxide emission becomes one of the main sources of air pollution, in recent years, countries continue to come out of relevant policies, higher nitrogen oxide emission standards are provided for the industries of air pollution sources such as thermal power, steel, cement, nonferrous metals, petrifaction, chemical industry and waste incineration, and efficient denitration becomes a major problem which is urgently needed to be solved by the industries.
At present, the main processes of denitration are selective non-catalytic reduction (SNCR) and Selective Catalytic Reduction (SCR) denitration technologies.
The SNCR-selective non-catalytic reduction denitration technology is a clean denitration technology which does not use a catalyst, and sprays reducing agents (such as ammonia water, urea solution and the like) containing amino into a furnace at the temperature range of 850-1100 ℃ to reduce and remove NOx in flue gas to generate nitrogen and water. It has the following disadvantages: firstly, the denitration efficiency is 30-60%, and the denitration efficiency is low; secondly, the temperature of the reaction zone is required to be high, and the temperature range is small (too low to react, too high reducing agent is oxidized); thirdly, the ammonia is easy to escape to cause secondary pollution.
The SCR-selective catalytic reduction denitration technology sprays reducing agents such as ammonia or urea into flue gas at the temperature of 120-450 ℃ under the action of a catalyst to realize denitration. At present, most of the prior markets adopt high-temperature SCR, a vanadium-based catalyst is adopted to manufacture a honeycomb SCR reactor at the temperature of 320-450 ℃, and a catalytic denitration reaction is realized when a reducing agent and nitrogen oxide flow through the SCR reactor. Although the denitration efficiency reaches 70-90%, the following problems also exist: firstly, vanadium in the adopted vanadium-based catalyst has great pollution to the environment and is not easy to be used subsequently; secondly, high temperature is needed to realize denitration, and the temperature of the exhaust smoke can not be reached generally; thirdly, dust in the flue gas easily causes honeycomb holes to be blocked; fourthly, sulfur in the flue gas also easily causes catalyst poisoning; fifthly, the honeycomb catalyst also has the problems of strength, abrasion and the like, needs to be replaced for 1 to 2 years, and has high cost. At present, medium-low temperature SCR denitration technology also appears, but the following problems also exist: firstly, the low-temperature SCR denitration efficiency is low; secondly, sulfur in the flue gas is easy to form ammonium sulfate with a reducing agent at low temperature to cause blockage and catalyst deactivation; thirdly, the manufacturing cost is high on the whole, the honeycomb SCR reactor needs to be replaced and cleaned irregularly, and the honeycomb SCR reactor cannot be used in a long-time working condition state.
The patent with the application number of CN201711347194.2 discloses a flue gas denitration process with a low-temperature denitration catalyst capable of being recycled, wherein NOx and SO are mixed in the flue gas denitration process2And H2The low-temperature catalyst is added into the O flue gas to realize low-temperature NOx removal, and finally the low-temperature catalyst is recycled through flue gas powder particles, ammonium sulfate washing by water and heating regeneration. However, the following disadvantages are also present: firstly, the process is complex, denitration and desulfurization are carried out together, ammonium sulfate and a catalyst are mixed, the catalyst can be regenerated only by washing and heating, and the treatment process flow is complex; the water consumption and the energy consumption are higher; secondly, the investment is large, and ammonia-making ammonia spraying equipment, a denitration reactor, gas-solid separation equipment, water washing equipment, microwave drying equipment, sulfuric acid evaporation and concentration equipment and a catalyst storage tank need to be arranged in a matched manner; thirdly, the catalyst after being washed needs to be heated and regenerated, so that catalyst agglomeration is easily caused, and the activity of the catalyst is influenced; fourthly, the water pollution problem is easy to occur in the water washing process.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a denitration method for industrial flue gas, which has the advantages of low investment, low operation cost, no blockage, no toxicity and high reliability, aiming at the problems in the background technology.
The technical scheme adopted by the invention for solving the technical problems is as follows: an industrial flue gas denitration method specifically comprises the following steps:
(1) arranging a desulfurization and dust removal device on the smoke exhaust pipeline to remove more than 95wt% of dust and sulfur in the smoke;
(2) adding an ammonia compound or an amine compound as a reducing agent into the flue gas treated in the step (1), and mixing the reducing agent with the flue gas;
(3) setting injection points on a smoke exhaust pipeline or/and smoke treatment equipment and the like; pulverizing into micron-sized transition metal or its compound as catalytic particles, and spraying reducing agent and NO at the spraying point by using conveying equipmentXAnd mixing with the flue gas;
(4) NO in high temperature smoke environment (100 ℃ C. and 450 ℃ C.)XAnd the molecules and the reducing agent are subjected to catalytic reduction reaction under the action of the catalytic particles to generate nitrogen and water, so that the reduction denitration reaction is realized.
Furthermore, a dust collector or a separator is arranged after the denitration reaction, catalytic particles are separated and collected from the flue gas at the dust collector or the separator, and the catalytic particles are sprayed into a flue gas pipeline or/and flue gas treatment equipment and the like through conveying equipment after being collected, so that the circular catalytic denitration is realized. The catalytic particulates collected by the dust collector can be separated by a catalytic particulate regeneration device.
Further, in the step (1), the desulfurization and dust removal equipment comprises a desulfurization device and a gas-solid separation device, and desulfurization agents are sprayed into the flue gas through the desulfurization device to realize SO2Removed and converted into solid products, and collected together with dust in the flue gas at a gas-solid separation device. The gas-solid separation device can be an electric dust collector, a cloth bag dust collector or a cyclone dust collector.
Furthermore, the desulfurization agent contains catalytic oxidant components, so that the desulfurization effect can be greatly improved, 99-100% of sulfur can be removed, and the influence on subsequent denitration is reduced.
Furthermore, the desulfurizing agent can contain a surfactant, such as Tween 80, stearic acid or sodium dodecyl benzene sulfonate, SO as to improve SO in flue gas2And the adsorption effect of fly ash, and the separation effect of the gas-solid separation device is improved.
Furthermore, a reducing agent is added into the flue gas which is not treated in the step (1), so that the sufficient reaction time of the reducing agent and the nitrogen oxide is prolonged, and the reducing agent can be optionally added or not added subsequently.
Further, the ammonia compound or the amine compound is added in the form of a solution.
Further, the catalytic particles are compounds containing transition metal elements, preferably non-toxic transition metal compounds capable of realizing low-temperature (100-.
Furthermore, the catalytic particles mainly comprise manganese oxide and iron oxide ore, are ground to 60-80 microns, and are pumped into flue gas by a gas delivery pump.
Furthermore, the catalytic particles can also be processed by adopting light clay dipped with a transition metal compound solution, so that the gas delivery is convenient.
Furthermore, the catalytic particles can be atomized and sprayed into the flue gas in a suspension or solution mode.
Further, the catalytic particles are preferably 100-500-mesh catalytic particles and are sprayed according to the amount of 100-3000kg/h, and the specific spraying amount can be determined according to the initial NO of the kiln tail flue gasXThe concentration and the smoke gas amount are adjusted.
Further, the temperature of the catalytic particle spraying area is between 100 ℃ and 500 ℃, so that the sintering deactivation of the catalytic particles is prevented.
Further, a plurality of injection points can be arranged, and different catalytic particles can be injected to carry out catalytic reaction according to different temperatures of the injection points.
Further, the smoke exhaust pipeline is a pipeline through which smoke flows between a chimney and a smoke generated by the smoke exhaust pipeline; the flue gas treatment equipment mainly comprises a waste heat recovery device, a dust collector, desulfurization and denitrification equipment and other equipment for removing flue gas pollution.
The technical principle is as follows:
aiming at the problems that the prior SCR equipment for denitration in flue gas is easy to block and inactivate, the effective use amount of the equipment is influenced, and the like, the catalytic particles are adopted to replace the traditional SCR honeycomb/plate-shaped filter structure, are conveyed into the flue gas containing a reducing agent and nitrogen oxides through gas high pressure and are fully mixed with the flue gas, and promote the reaction of the reducing agent and the nitrogen oxides in the flue gas, so that the effect of an SCR catalyst is achieved, wherein the catalytic particles are collected through a dust collector, are not discharged into the atmosphere, influence on pollutant emission is avoided, and the catalytic particles can be recycled.
Compared with the patent application CN201711347194.2, the method adopts the steps of removing sulfur and nitrate integrally, then separating the catalyst, washing and regenerating, the method adopts the steps of removing sulfur and then removing nitrate, the catalyst does not need to be regenerated complexly, can be directly regenerated and recycled, has short cycle period and high equipment operation reliability, and can also fully utilize fly ash and flue gas to desulfurize in high-dust flue gas, thereby greatly reducing the overall investment and the operation cost.
The invention has the beneficial effects that:
1. the catalytic powder is adopted to replace the traditional SCR denitration reaction equipment for denitration, and the catalytic particles can react with NO in the flue gasXThe catalyst is fully contacted with the reducing agent, so that compared with honeycomb pipeline type denitration adopted by an SCR (selective catalytic reduction) denitration device, the catalyst is greatly improved to participate in catalytic reaction, the catalytic efficiency is improved, and meanwhile, the problems of abrasion of an SCR denitration reaction pipeline and the like are not needed to be worried;
2. the catalytic powder is adopted to replace the traditional SCR denitration reaction equipment for denitration, so that the problems of SCR denitration blockage and the like can be effectively avoided, and the effective operation time of the whole facility is greatly prolonged;
3. by adopting a distributed desulfurization and denitrification mode, particularly adopting a desulfurizer containing catalytic oxidant components, the desulfurization effect of over 99wt% is realized, the influence of sulfur in flue gas on denitrification is effectively reduced, and the subsequent complex regeneration process of the catalyst is avoided;
4. after the method is adopted, the poisoning and inactivation phenomena of the catalyst do not need to be worried about, wherein the catalytic particles can be recycled, and when the activity of the catalytic particles is insufficient, a new catalyst can be directly added for substitution without shutdown maintenance;
5. because the possibility of blockage and inactivation is not needed to be worried about, a low-temperature catalyst can be adopted, and a toxic (vanadium compound) high-temperature catalyst is relatively adopted, the problem of secondary pollution is not needed to be worried about, and the cost of the catalyst is greatly reduced.
Drawings
FIG. 1 is a schematic view of the working conditions of embodiment 1 of the present invention;
FIG. 2 is a schematic view of the working conditions of embodiment 2 of the present invention;
FIG. 3 is a schematic view of the working conditions of embodiment 3 of the present invention;
in the figure: 1-1 of a desulfurization water agent, 1-2 of a desulfurization water agent containing a catalytic oxidant component, 1-3 of a desulfurization water agent containing a reducing agent, 2 of a reducing agent, 3 of an electrostatic dust collector, 4 of an ash flying warehouse, 5 of a bag dust collector, 6 of catalytic denitration equipment, 7 of a material supplementing system, 8 of a chimney, 9 of a fan, 10 of a low-temperature denitration tower and 11 of a catalytic powder regeneration system.
Detailed Description
The invention is further explained with reference to the drawings and the embodiments.
Example 1
A 700t/d glass kiln with the air volume of 13.5 ten thousand cubic meters per hour; wherein the flue gas SO2Initial emission maximum 3200mg/Nm3(ii) a The method adopts electrostatic dust removal plus (double) SCR plus SDA semi-dry desulphurization plus bag type dust collector to carry out flue gas decontamination, wherein the discharge of flue gas dust is 15mg/Nm3，NOXEmission was 165mg/Nm3，SO2The discharge was 195mg/Nm3With the requirements of local government on ultra-low emission and high use cost of SCR (two sets), the average dust emission value is 4mg/Nm in 24 hours after the scheme of the embodiment is adopted3，SO2Mean emission 6mg/Nm3，NOXMean emission 43mg/Nm3And the requirement of ultra-low emission is met.
The specific implementation conditions are as follows: in the process of electrostatic dust collection, SCR and SDA semi-dry desulfurization and bag type dust collector, the process is modified into semi-dry catalytic desulfurization (desulfurizing water agent), electrostatic dust collection, catalytic particle denitration and bag type dust collection, as shown in figure 1, wherein a high-temperature SCR facility is cancelled, and catalytic particle denitration equipment is added; the desulfurization position of the SDA semi-dry desulfurization is adjusted, the desulfurization agent is replaced, the technical improvement is about 300 thousands, the cost is low, the effect is improved well, the SCR catalyst does not need to be switched, and the use cost of the SCR catalyst is greatly reduced; the method specifically comprises the following steps:
(1) atomizing and spraying 1-1 (5% sodium hydroxide aqueous solution) of a desulfurization water agent at the position of a flue gas pipeline discharged from a furnace, wherein the spraying amount is 0.5-1.0t/h, and under the action of flue gas fly ash and the desulfurization water agent, the glass kiln flue gas fly ash is rich in alkaline components, SO that SO can be realized2The solid sulfate (sodium sulfate, calcium sulfate and the like) is converted, and the solid sulfate and the flue gas fly ash are collected at an electrostatic dust collector 3, wherein the electrostatic dust collector can separate 98 percent of dust and sulfur;
(2) a reducing agent 2 injection point is arranged on a flue gas pipeline behind the electrostatic dust collector 3, at the moment, the flue gas is basically free of sulfur, dust and other impurities which influence denitration, 0.3-0.5t/h of ammonia water with the ammonia content of 20% is added as a reducing agent according to actual emission data, and the reducing agent is rapidly and uniformly mixed with the high-temperature (the temperature is about 300 ℃) flue gas;
(3) a catalytic powder spraying point is arranged behind the electrostatic dust collector 3, and the grinded micron-sized iron oxide, cerium oxide, copper oxide, manganese oxide and nickel oxide are sprayed into the flue gas at the spraying point by a gas delivery pump in the catalytic denitration device 6 according to the mass ratio of 2:1:2:4:1 at high pressure of 500kg/h and are fully mixed with the flue gas;
(4) NO under the high-temperature smoke environment (180-XThe molecules and a reducing agent are subjected to catalytic reduction reaction under the action of the catalytic particles to generate nitrogen and water, so that the reduction denitration reaction is realized;
the catalytic particles are collected at the bag dust collector 5, and enter the catalytic denitration device 6 again after being collected, and are sprayed into the smoke exhaust pipeline through the gas delivery pump in the catalytic denitration device 6 again to realize circulating catalytic denitration, wherein the injection amount of the catalytic powder is according to NOXThe discharge is adjusted in real time, and meanwhile, when the catalytic powder is inactivated, new catalytic particles can be replaced or supplemented to improve the activity.
The embodiment integrally realizes ultralow emission and no waste water generation.
Example 2
In a household garbage incineration power plant project in a certain county, 500t of garbage is treated in the first-stage project day, 300t of garbage is treated in the second-stage project day, and the first-stage project and the second-stage projectThe daily garbage disposal amount is 800t, the current flue gas treatment adopts the treatment process of 'SNCR + semi-dry desulfurization (sodium bicarbonate) + bag type dust removal + low-temperature SCR', wherein NOXInitial concentration 350mg/Nm3175mg/Nm after low-temperature SCR denitration3Mainly because the activity is not enough after low temperature SCR denitration uses one section, leads to the catalytic denitration effect poor, although satisfies national standard and discharges, nevertheless because peripheral resident reflects strongly, carries out ultralow emission and reforms transform. After the scheme of the embodiment is adopted, the average value of dust emission in 24 hours is 2mg/Nm3，SO2Mean emission 3mg/Nm3，NOXEmission mean 45mg/Nm3And the requirement of ultra-low emission is met.
In the embodiment, in the process of 'SNCR + semi-dry desulfurization (sodium bicarbonate) + bag-type dust removal + low-temperature SCR', the process is modified to 'SNCR + semi-dry catalytic desulfurization (desulfurizing water agent) + parallel high-efficiency cyclone dust collector + catalytic particulate denitration + bag-type dust removal', as shown in fig. 2, wherein a low-temperature SCR facility is cancelled, and parallel high-efficiency cyclone dust collector and catalytic denitration equipment are added; the sodium bicarbonate serving as a desulfurization agent is adjusted to be a desulfurization water agent containing a catalytic oxidant, the technical improvement is about 400 thousands, the cost is low, the effect is improved, the SCR catalyst does not need to be replaced during production halt, the problems of blockage, failure and the like do not need to be worried about, the utilization rate of equipment is greatly improved, and the production halt is about 30 days per year; the method specifically comprises the following steps:
(1) spraying 1-2 (5% calcium hydroxide solution +1% PWSNA catalytic solution) of desulfurizing agent containing catalytic oxidant component into flue gas pipeline, and under the action of flue gas flyash, desulfurizing agent and catalytic oxidant, implementing SO2The solid sulfate is converted into solid sulfate and is collected with the flue gas fly ash at a high-efficiency cyclone dust collector connected in parallel, wherein the high-efficiency cyclone dust collector can separate 96 percent of dust and sulfur;
(2) a reducing agent 2 injection point is arranged on a flue gas pipeline connected with the high-efficiency cyclone dust collector in parallel, 0.3-0.5t/h of denitration solution with 25% of urea content is added as a reducing agent according to actual emission data, and the reducing agent and the high-temperature flue gas are quickly and uniformly mixed;
(3) preparing ferric nitrate, cerium sulfate, copper nitrate, manganese nitrate and water into a solution according to the mass ratio of 2:1:2:5:50, mixing and infiltrating the solution with 20kg of 500-mesh kaolin powder and 20kg of 500-mesh vermiculite powder, and finally drying and grinding the mixture to prepare catalytic powder;
an injection point is arranged behind the high-efficiency cyclone dust collector, and the catalytic powder is injected into the flue gas at the injection point by a gas delivery pump at high pressure of 600kg/h and is fully mixed with the flue gas;
(4) NO under the high-temperature smoke environment (150 ℃ F. & 250 ℃ C.)XThe molecules and a reducing agent are subjected to catalytic reduction reaction under the action of the catalytic particles to generate nitrogen and water, so that the reduction denitration reaction is realized;
the catalytic particles are collected at the bag dust collector 5, enter the catalytic denitration device 6 after being collected, and are sprayed into the smoke exhaust pipeline through the gas conveying pump in the catalytic denitration device 6 again to realize circulating catalytic denitration, wherein the injection amount of the catalytic powder is according to NOXThe discharge is adjusted in real time, and meanwhile, when the catalytic powder is inactivated, new catalytic particles can be replaced or supplemented to improve the activity.
The embodiment integrally realizes ultralow emission and no waste water generation.
Example 3
In a certain thermal power plant, the generated energy is 330MW, the flue gas amount is 110 ten thousand square meters per hour, at present, a treatment process of 'SNCR + high-temperature electric precipitation + high-temperature SCR + bag type dust removal + fan + limestone gypsum wet desulphurization + heat exchanger + chimney discharge' is adopted, wherein the flue gas and dust discharge is 2mg/Nm3，SO2The emission was 20mg/Nm3，NOXThe emission was 35mg/Nm3The method meets the requirement of ultra-low emission, but has the problems of high operation cost, easy blockage of high-temperature SCR and the like. After the scheme of the embodiment is adopted, the average value of dust emission in 24 hours is 2.5mg/Nm3，SO2Mean emission 5mg/Nm3，NOXEmission mean 38mg/Nm3The requirement of ultralow emission is met, the operation cost is greatly reduced, and the manual loss of water and electricity is reduced. The specific implementation conditions are as follows:
in the process of 'SNCR + high-temperature electric precipitation + high-temperature SCR + bag-type dust removal + fan + lime gypsum wet desulphurization + heat exchanger + chimney exhaust', the process is modified into 'SNCR + semi-dry catalytic desulphurization + bag-type dust removal + fan + catalytic powder denitration (with the addition of a regeneration system) + a denitration tower + chimney exhaust', as shown in FIG. 3, wherein the high-temperature electric precipitation, the high-temperature SCR and the heat exchanger are cancelled; the method is changed into a method of firstly desulfurizing and then denitrating, a lime gypsum wet desulfurization tower is changed into a denitration tower, a liquid low-temperature catalytic denitration agent is adopted for cyclic denitration, the technical improvement is about 600 ten thousand, the operation cost is reduced by 0.2 min/KW, the annual cost is saved by 522.7 ten thousand yuan, meanwhile, the SCR catalyst does not need to be replaced when the production is stopped, the problems of blockage, failure and the like do not need to be worried about, the utilization rate of equipment is greatly improved, and the production is stopped for about 30 days each year; the method specifically comprises the following steps:
(1) atomizing and spraying 1-3 of a desulfurization water agent containing a reducing agent at a flue gas pipeline discharged from a furnace, wherein the desulfurization agent is prepared from 20% of ammonia water and a desulfurization catalyst (5% of PWSNB catalytic solution) according to the mass ratio of 90:10, and the desulfurization water agent is added according to the mass ratio of 0.3-0.8t/h, wherein the ammonia water in the desulfurization water agent also has the characteristics of the reducing agent, and can be used for subsequent denitration after desulfurization is completed; because the wind speed is lower, SO can be effectively realized2More than 97 percent of the sulfate is converted into solid sulfate and is collected at a bag dust collector 5;
(2) arranging a spraying point behind a bag dust collector 5, preparing manganese sulfate, polymeric ferric sulfate, copper sulfate, rare earth powder, Tween 80 and water into a catalytic water solution according to the mass ratio of 4:2:1:1:1:50, and spraying the catalytic water solution into the flue gas with ammonia water at the spraying point through a high-pressure water pump according to the spraying amount of 2.0-3.0t/h for mixing;
(3) under the high temperature state (100-;
in a denitration tower modified by a desulfurization tower, a catalytic water agent and solid components are collected at a demister and converged to the bottom of the denitration tower; the collected catalytic water agent is sprayed into the flue gas again through the catalytic denitration device, so that cyclic catalytic denitration is realized, the catalytic water agent is gradually inactivated along with the repeated use of the catalytic water agent, and the catalytic water agent can be pumped to the catalyst for regeneration and activation.
Example 4
A 5960KW supertanker, which, along with the strict NOx emission standards stipulated by the International Maritime Organization (IMO), implements desulfurization and denitrification and ultra-low emissions by using the present embodiment, comprising in particular the steps of:
(1) a desulfurizer device, a cyclone dust collector and an electric dust collector are arranged at the smoke outlet of the engine; spraying desulfurization water agent (5% sodium hydroxide prepared from seawater) in an atomized manner with a spraying amount of 0.5-1t/h, wherein SO can be realized under the action of flue gas fly ash and desulfurization water agent2Converting into solid sulfate (sodium sulfate, calcium sulfate, etc.), and collecting with flue gas fly ash in a cyclone dust collector and an electrostatic precipitator; wherein 96% of dust and sulfur can be separated; wherein the collected fly ash can be stored in a fly ash storage;
(2) a reducing agent injection point is arranged on a flue gas pipeline behind the electrostatic dust collector, at the moment, the flue gas is basically free of sulfur, dust and other impurities which influence denitration, 0.3-0.5t/h of ammonia water with the ammonia content of 20% is added as a reducing agent according to actual emission data, and the reducing agent is rapidly and uniformly mixed with the high-temperature (the temperature is about 200 ℃) flue gas;
(3) a catalytic powder spraying point is arranged behind the electrostatic dust collector 3, the milled micron-sized iron oxide, cerium oxide, copper oxide, manganese oxide and nickel oxide powder are sprayed into the flue gas at the spraying point at a high pressure of 200kg/h by a gas delivery pump in the catalytic denitration device 6 according to the mass ratio of 2:1:2:4:1, and are fully mixed with the flue gas;
(4) NO under the high-temperature smoke environment (180-XThe molecules and a reducing agent are subjected to catalytic reduction reaction under the action of the catalytic particles to generate nitrogen and water, so that the reduction denitration reaction is realized;
the catalytic particles are collected at the bag dust collector, and then enter the catalytic denitration equipment again after being collected, and are sprayed into the smoke exhaust pipeline through the gas conveying pump in the catalytic denitration equipment again to realize circulating catalytic denitration, wherein the injection amount of the catalytic powder is according to NOXThe discharge is adjusted in real time, and meanwhile, when the catalytic powder is inactivated, new catalytic particles can be replaced or supplemented to improve the activity.
In the embodiment, the ultralow emission of dust, sulfur dioxide and nitrogen oxides can be realized, the black smoke phenomenon is avoided by three-stage filtration, and the addition of the water aqua is less and the white smoke is avoided. Thoroughly solve the ship emission problem.
Various modifications and variations of the present invention may be made by those skilled in the art, and they are also within the scope of the present invention provided they are within the scope of the claims of the present invention and their equivalents. What is not described in detail in the specification is prior art that is well known to those skilled in the art.

Claims (10)

1. The industrial flue gas denitration method is characterized by comprising the following steps:
(1) arranging a desulfurization and dust removal device on the smoke exhaust pipeline to remove more than 95wt% of dust and sulfur in the smoke;
(2) adding an ammonia compound or an amine compound as a reducing agent into the flue gas treated in the step (1), and mixing the reducing agent with the flue gas;
(3) arranging an injection point on a smoke exhaust pipeline or/and smoke treatment equipment, grinding the powder into micron-sized transition metal or compound thereof serving as catalytic particles, and injecting reducing agent and NO into the injection point through a conveying deviceXAnd mixing with the flue gas;
(4) in high temperature flue gas environment, NOXAnd the molecules and the reducing agent are subjected to catalytic reduction reaction under the action of the catalytic particles to generate nitrogen and water, so that the reduction denitration reaction is realized.
2. The industrial flue gas denitration method according to claim 1, characterized in that: and after the denitration reaction, a dust collector or a separator is arranged, catalytic particles are separated from the flue gas and collected at the dust collector or the separator, and the catalytic particles are sprayed into a flue gas pipeline or/and flue gas treatment equipment through conveying equipment after collection, so that the circular catalytic denitration is realized.
3. The industrial flue gas denitration method according to claim 1 or 2, characterized in that: in the step (1), the desulfurization and dust removal equipment comprises a desulfurization device and a gas-solid separation device, and desulfurization agents are sprayed into flue gas through the desulfurization device to realize SO2Removed and converted into solid products, and collected together with dust in the flue gas at a gas-solid separation device.
4. The industrial flue gas denitration method according to claim 3, characterized in that: the desulfurization agent contains a surfactant.
5. The industrial flue gas denitration method according to claim 3, characterized in that: the desulfurization agent contains a catalytic oxidizer component.
6. The industrial flue gas denitration method according to claim 1 or 2, characterized in that: and (2) adding a reducing agent into the flue gas which is not treated in the step (1), and optionally adding or not adding the reducing agent subsequently.
7. The industrial flue gas denitration method according to claim 1 or 2, characterized in that: the catalytic particles are compounds containing transition metal elements, and the transition metal is a fourth period element.
8. The industrial flue gas denitration method according to claim 1 or 2, characterized in that: the catalytic particles are processed from light clay impregnated with a solution of a transition metal compound.
9. The industrial flue gas denitration method according to claim 1 or 2, characterized in that: the catalytic particles are atomized and sprayed into the flue gas in a suspension or solution mode.
10. The industrial flue gas denitration method according to claim 1 or 2, characterized in that: the smoke exhaust pipeline is a pipeline through which smoke flows between a chimney and a smoke generated by the smoke; the flue gas treatment equipment mainly comprises a waste heat recovery device, a dust collector or desulfurization and denitrification equipment.
CN202010745037.2A 2020-07-29 2020-07-29 Industrial flue gas denitration method Pending CN111821856A (en)

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Application publication date: 20201027