CN112762707A - Embedded SCR + SNCR flue gas denitration device and method for belt type roasting machine - Google Patents

Embedded SCR + SNCR flue gas denitration device and method for belt type roasting machine Download PDF

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Publication number
CN112762707A
CN112762707A CN202110114143.5A CN202110114143A CN112762707A CN 112762707 A CN112762707 A CN 112762707A CN 202110114143 A CN202110114143 A CN 202110114143A CN 112762707 A CN112762707 A CN 112762707A
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flue gas
scr
flue
denitration
section
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张福明
王波
颜晓光
张卫华
智谦
张全申
孙照燕
王飞
胡长松
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Beijing Shougang International Engineering Technology Co Ltd
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Beijing Shougang International Engineering Technology Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/02—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity of multiple-track type; of multiple-chamber type; Combinations of furnaces
    • F27B9/028—Multi-chamber type furnaces
    • 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
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen 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
    • 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
    • B01D53/77—Liquid phase processes
    • B01D53/79—Injecting reactants
    • 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
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen 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
    • B01D53/86—Catalytic processes
    • B01D53/90—Injecting reactants
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/3005—Details, accessories, or equipment peculiar to furnaces of these types arrangements for circulating gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/001—Extraction of waste gases, collection of fumes and hoods used therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

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  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

An embedded SCR + SNCR flue gas denitration device and method for a belt type roasting machine belong to the technical field of sintering and pellet flue gas denitration. The flue gas in the production process of the belt type roasting machine mainly meets the production requirement, the flue gas is recycled for many times, and the temperature is changed for many timesAnd (4) transforming. NO in flue gasXThe method is mainly generated in a cooling 1 section, a roasting soaking section and a preheating section, and the part of flue gas enters a main air draft system after passing through a back air draft system, wherein the temperature of the back air draft system is 350 ℃. Therefore, the invention provides that the SCR denitration device is arranged in the regenerative air system, the regenerative air is subjected to denitration treatment and returns to the air draft drying section of the belt type roasting machine after the denitration treatment is finished, and the production requirement is met. Simultaneously, an SNCR denitration device is arranged in the roasting soaking section and the preheating section to assist in denitration.

Description

Embedded SCR + SNCR flue gas denitration device and method for belt type roasting machine
Technical Field
The invention relates to an embedded SCR + SNCR flue gas denitration device of a belt type roasting machine and a method thereof, belonging to the technical field of sintering and pellet flue gas denitration.
Background
The belt type pellet roasting process has the advantages of simple process, compact arrangement, high heat efficiency and the like, and is particularly suitable for the requirements of large production scale and large scale. However, the amount of flue gas generated in the production process of the travelling grate is large, the concentration of NOx in the flue gas is high, and the concentration of NOx in a main air draft system can reach 400-500 mg/Nm3The actual oxygen content is 18%. In order to meet the requirement of ultra-low emission, a process route of adding an SCR (selective catalytic reduction) denitration reaction device into a main air draft system is mostly adopted for treating NOx at present. Because the flue gas temperature of the main air exhaust system is between 150 ℃ and 160 ℃, when the SCR denitration process is adopted, a flue gas heating system is required to be arranged, so that the energy waste is great, and the operation cost is high.
According to the characteristics of the production process, the flue gas in the production process of the belt type roasting machine mainly meets the production requirement, the flue gas is recycled for many times, and the temperature is changed for many times. Therefore, the denitration device can be set at a proper temperature section, NOx in the flue gas can be removed without heating the flue gas, and the requirement of standard emission is met.
Disclosure of Invention
The invention provides an embedded SCR + SNCR flue gas denitration device of a belt type roasting machine and a method thereof, which are used for denitration of flue gas according to temperature distribution of a wind system in the production process of the belt type roasting machine and NOXPrinciple of generation, NO in pellet flue gas of straight grateXMainly generated in the cooling 1 section, the roasting soaking section and the preheating section, and exhausted flue gas enters a regenerative air heating system. The flue gas temperature of the preheating section and the roasting soaking section is 900-1100 ℃, and is in the temperature range of selective non-catalytic reduction SNCR denitration; the flue gas temperature of the back hot air system is 350 ℃ below zero, and is in the temperature range of selective catalytic reduction SCR denitration.
The invention provides an SNCR (selective non-catalytic reduction) denitration device arranged in a roasting soaking section and a preheating section, which is used for primary denitration and reducing NO (nitric oxide) in flue gas from the sourceXConcentration; an SCR denitration device is arranged in front of the regenerative fan, the regenerative air is subjected to fine denitration treatment, and the treated flue gas returns to the air draft drying section of the belt type roasting machine to meet the production requirement. So that the finally discharged flue gas meets the environmental protection standard. In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
an embedded SCR + SNCR flue gas denitration device of a belt type roasting machine comprises an annular air cooler 1, a top flue 2, an SNCR atomizing spray gun 3, a backheating air box 4, an electric air valve 5, an ammonia injection device 6, a static mixer 7, an SCR denitration device 8, a low-leakage airtight air valve 9, a backheating fan 10, a blowing dry air blower 11, a main suction electric dust remover 12, a desulfurization device 13, a main exhaust fan 14, a blowing dry electric dust remover 15, a blowing dry exhaust fan 16 and a chimney 17;
holes are formed in the side walls of the smoke hood at the tops of the preheating section and the roasting soaking section, and an SNCR (selective non-catalytic reduction) atomizing spray gun 3 is installed; an SCR denitration device 8 is arranged in front of a regenerative fan 10, a regenerative air box 4 is connected with an inlet of an SCR reaction device 8 through a flue, flue gas in the regenerative air box 4 enters the SCR reaction device 8 through the flue, and an ammonia injection device 6 is arranged in the flue at the inlet of the SCR reaction device 8; after the air draft drying section, the main air draft dust collector 12, the desulphurization device 13 and the main exhaust fan 14 are connected in sequence and discharged to a chimney 17; an electric air valve 5, an ammonia injection device 6 and a static mixer 7 are sequentially arranged on an inlet flue of an SCR (selective catalytic reduction) denitration device 8, a regenerative fan 10 is arranged on an outlet flue of the SCR denitration device 8, a bypass flue and a low-leakage closed air valve 9 are arranged on a regenerative air box 4, the bypass flue is connected with the regenerative fan 10, and the other end of the regenerative fan 10 is connected with an air draft drying section; one end of the blast drying section is connected with the cooling second section through a blast drying blower 11, the other end of the blast drying section is connected with a chimney 17 through a drying electric dust collector 15 and a blast drying exhaust fan 16 in sequence, the annular air cooler 1 is connected with the top flue 2 through the cooling first section and the cooling second section, and the SNCR atomizing spray gun 3 is positioned in the top flue 2.
An embedded SCR + SNCR flue gas denitration method of a belt type roasting machine comprises the following steps:
step one, holes are formed in the side walls of top smoke hoods of a preheating section and a roasting soaking section, SNCR atomizing spray guns 3 are installed, and the spray guns are arranged on two sides of the top smoke hoods of the preheating section and the roasting soaking section; the position of the spray gun is selected to ensure that the sprayed reducing agent is fully mixed with the flue gas, and the residence time of the sprayed reducing agent is not less than 0.3s in the reaction temperature range of 900-1100 ℃.
Step two, the SNCR atomization spray gun 3 is provided with a cooling air and atomization air system;
step three, spraying a reducing agent into a smoke hood at the top of the preheating section and the roasting soaking section through an SNCR (selective non-catalytic reduction) atomization spray gun 3;
step four, the reducing agent sprayed by the SNCR atomization spray gun 3 and the nitrogen oxide in the flue gas are subjected to reduction reaction to realize primary denitration, the denitration efficiency can reach 30% -40%, and the concentration of NOx is reduced to 600mg/Nm3The following;
fifthly, the part of the reducing agent which is sprayed by the SNCR system and does not participate in the reaction and the flue gas pass through the material layers of the preheating section and the roasting soaking section and then enter the smoke hood at the bottom of the preheating section and the roasting soaking section;
sixthly, flue gas exhausted from the smoke hoods at the bottoms of the preheating section and the roasting soaking section enters a regenerative air box 4 to be mixed, and the flue gas in the regenerative air box 4 enters an SCR denitration device 8 through a flue;
seventhly, arranging an ammonia injection device 6 on an inlet flue entering the SCR denitration device 8;
step eight, arranging a static mixer 7 behind the ammonia injection device 6 on the inlet flue of the SCR denitration device 8, and uniformly mixing the ammonia injected by the ammonia injection device 6 with the flue gas through the mixing action of the static mixer;
ninth, arranging a catalyst in the SCR denitration device, wherein the aperture and the type of the catalyst are determined according to the flue gas condition;
step ten, the SCR denitration device is provided with a soot blowing device, and the soot blowing device adopts an acoustic wave soot blower or a rake type soot blower;
step eleven, after the denitration reaction of the flue gas in the SCR denitration device 8 is finished, the flue gas is sent into an air draft drying section of the belt type roasting machine through a heat return fan 10;
and step twelve, the flue gas finally enters a main air draft system after passing through an air draft drying section, and is discharged to a chimney 17 through a main air draft electric dust collector 12, a desulfurization device 13 and a main air draft fan 14 in sequence.
The reducing agent is liquid ammonia or ammonia water.
The heat recovery air box 4 is provided with a bypass flue and a low-leakage closed air valve 9, and an electric air valve 5 is arranged on an inlet flue of the SCR denitration device 8; in the furnace baking stage, the flue gas can directly enter the regenerative fan 10 through the bypass flue by opening the low-leakage closed air valve 9 and closing the electric air valve 5, and does not pass through the SCR denitration device 8; and when the system is normally put into operation, the low-leakage airtight air valve 9 is closed, the electric air valve 5 is opened, and the flue gas enters the regenerative fan 10 after passing through the SCR denitration device 8.
The SNCR denitration system is arranged at the proper position of the preheating section and the roasting soaking section, and the specific scheme is as follows: holes are formed in the side walls of the smoke hoods at the tops of the preheating section and the roasting soaking section, atomizing spray guns are installed, the number and the positions of the spray guns are determined according to the distribution conditions of the temperature and the flow velocity of internal smoke, reducing agents are sprayed into the smoke hoods at the tops of the preheating section and the roasting section through the atomizing spray guns, the reducing agents and nitrogen oxides in the smoke are subjected to reduction reaction, and the purpose of primary denitration is achieved. Set up SCR denitrification facility before backheat fan, the concrete scheme is: the flue gas that preheating section and calcination soaking section exhaust mixes in backheating bellows, and backheating bellows passes through flue and SCR reactor entry linkage, and the flue gas in the backheating bellows passes through the flue and gets into the SCR reactor, sets up ammonia injection apparatus at SCR reactor entry flue, supplements the reductant that the denitration needs, and the flue gas accomplishes the denitration reaction in the SCR reactor, realizes smart denitration.
Preferably, the SNCR spray gun is a high-temperature-resistant and wear-resistant spray gun which is provided with a cooling air and atomizing air system.
Preferably, the position of the SNCR spray gun is selected to ensure that the injected reducing agent is fully mixed with the flue gas and has the residence time of not less than 0.3s in the reaction temperature region of 900-1100 ℃.
Preferably, the flue gas of the top smoke hood of the preheating section and the roasting soaking section flows in from the top, and in order to reduce the influence of airflow, a spray gun with strong penetrating power is selected.
Preferably, the reducing agent is liquid ammonia or ammonia water, the injected reducing agent is gasified into ammonia gas by high-temperature flue gas in the smoke hood at the top of the preheating section and the roasting soaking section, and the ammonia gas and nitrogen oxides in the flue gas are subjected to reduction reaction. The denitration efficiency can reach 30 to 40 percent, and the concentration of NOx is reduced to 600mg/Nm3The following;
preferably, the reducing agent sprayed by the SNCR spray gun is partially not reacted, and the unreacted ammonia gas and the unreacted flue gas enter the smoke hood at the bottom of the preheating section and the roasting soaking section through the material layers of the preheating section and the roasting soaking section, and the temperature is reduced to 350 ℃.
Preferably, the ammonia injection device that SCR reactor entry flue set up comprises ammonia injection device and static mixer, and the ammonia of spouting is under the vortex mixing action of static mixer, and the flue gas misce bene satisfies the requirement of high-efficient denitration.
Preferably, flue gas and unreacted ammonia gas in the preheating section and the roasting section bottom smoke hood enter the SCR denitration device through a flue, and the flue gas completes denitration reaction in the SCR denitration device.
Preferably, a denitration catalyst is arranged in the SCR reactor, the number and the type of the catalyst layers are determined according to the flue gas condition, and the reactor is provided with a soot blower.
Preferably, the flue gas after denitration reaction in the SCR denitration device returns to the air draft drying section of the belt type roasting machine through a heat recovery fan, so that the production requirement is met.
Preferably, the flue gas in the air draft drying section finally enters a main air draft system and is discharged to a chimney through a main air draft dust collector, a desulfurization device and a main air draft fan in sequence.
Particularly, the ammonia injection amount of the top smoke hood of the preheating section and the roasting soaking section and the ammonia injection amount of the inlet flue of the SCR denitration device can be manually or automatically adjusted in the process, the ammonia injection amounts are controlled according to the concentration of nitrogen oxides of the emission outlet, the ammonia injection amounts are reasonably distributed, the emission requirement is met, the ammonia injection amount is reduced, and the smoke is prevented from generating NH at the low-temperature section at the downstream4HSO4。
Particularly, a bypass flue and a low-leakage closed air valve are arranged in the regenerative air system, and flue gas can directly enter the regenerative fan from the regenerative air box through the bypass flue and does not pass through the SCR denitration device. The adverse effects of wet flue gas and the like generated in the furnace baking stage during the initial operation of the pellet system on the catalyst can be effectively avoided.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the traditional denitration method that the whole flue gas SCR is arranged in the main air suction system of the belt type roasting machine, the flue gas does not need to be supplemented with heat, energy is saved, and the operation cost is greatly reduced.
2. The flue gas temperature of the regenerative air system of the belt type roasting machine is 350 ℃, and the flue gas temperature is in the optimal reaction temperature range of the catalyst, so that the utilization rate of the catalyst is improved, and the service life of the catalyst is prolonged.
3. The beneficial conditions of the pelletizing process of the belt type roasting machine are utilized, two-stage denitration is arranged, and the advantages of the SCR technology and the SNCR technology are fully utilized.
4. The SCR technology is utilized to consume the unreacted ammonia of the SNCR system, the denitration efficiency is improved, the consumption of ammonia is reduced,
relieve the generation of NH at the low-temperature section at the downstream of the flue gas4HSO4Causing the risk of ash blockage and hardening.
5. Compared with the main smoke extraction amount, the partial smoke amount is small, a GGH heat exchanger, a smoke heating device and the like are not needed, the system scale is small, the occupied area is saved, and the initial investment is low.
Drawings
Fig. 1 is a flow chart of an embedded SCR + SNCR flue gas denitration method of a belt roasting machine provided by the invention.
The reference numbers illustrate:
1-circular air cooler, 2-top flue, 3-SNCR atomizing spray gun, 4-backheating air box, 5-electric air valve, 6-ammonia injection device, 7-static mixer, 8-SCR denitration device, 9-low leakage closed air valve, 10-backheating air fan, 11-blast dry air blower, 12-main suction electric dust remover, 13-desulphurization device, 14-main exhaust fan, 15-blast dry electric dust remover, 16-blast dry exhaust fan, 17-chimney
Detailed Description
An embedded SCR + SNCR flue gas denitration method of a belt type roasting machine mainly comprises the following steps: the system comprises an air cooling ring 1, a top flue 2, an SNCR (selective non catalytic reduction) atomizing spray gun 3, a regenerative air box 4, an electric air valve 5, an ammonia injection device 6, a static mixer 7, an SCR (selective catalytic reduction) denitration device 8, a low-leakage closed air valve 9, a regenerative air fan 10, a dry blowing air blower 11, a main extraction electric dust remover 12, a desulfurization device 13, a main exhaust fan 14, a dry blowing electric dust remover 15, a dry blowing exhaust fan 16 and a chimney 17.
The method comprises the following steps:
1. the SNCR denitration system is arranged at the proper position of the preheating section and the roasting soaking section, and the specific scheme is as follows: holes are formed in the side walls of the top smoke hoods of the preheating section and the roasting soaking section, SNCR atomizing spray guns 3 are installed, the number and the positions of the spray guns are determined according to the distribution conditions of the temperature and the flow velocity of internal smoke, reducing agents are sprayed into the top smoke hoods of the preheating section and the roasting section through the SNCR atomizing spray guns 3, the reducing agents and nitrogen oxides in the smoke are subjected to reduction reaction, and the purpose of primary denitration is achieved.
2. Set up SCR denitrification facility 8 before backheat fan, the concrete scheme is: flue gas discharged from the preheating section and the roasting soaking section is mixed in the heat regeneration air box 4, the heat regeneration air box 4 is connected with an inlet of the SCR reaction device 8 through a flue, the flue gas in the heat regeneration air box 4 enters the SCR reaction device 8 through the flue, an ammonia injection device 6 is arranged at the inlet flue of the SCR reaction device 8 to supplement a reducing agent required by denitration, and the flue gas completes denitration reaction in the SCR reactor to realize fine denitration.
To further explain the contents of the present invention in detail, the following description is made with reference to the accompanying drawings.
As shown in fig. 1, the invention provides a method for denitration of pellet flue gas of a belt type roasting machine, which comprises the following steps:
step 1: holes are formed in the side walls of the top smoke hood of the preheating section and the roasting soaking section, SNCR atomizing spray guns 3 are installed, the spray guns are arranged on two sides of the top smoke hood of the preheating section and the roasting soaking section, the number and the positions of the spray guns are determined according to the internal temperature distribution condition, the temperature of an ammonia spraying area is preferably 900-1100 ℃, and the reaction residence time is not less than 0.3 s.
Step 2: the SNCR atomizing spray gun 3 should adopt a high-temperature-resistant and wear-resistant spray gun which is provided with a cooling air and atomizing air system. In order to reduce the influence of air flow and ensure sufficient reaction time, a spray gun with stronger penetrating power is selected.
And step 3: and (3) spraying a reducing agent into the smoke hood at the top of the preheating section and the roasting soaking section through the SNCR atomization spray gun 3, wherein the reducing agent can be liquid ammonia or ammonia water.
And 4, step 4: the reducing agent sprayed by the SNCR atomization spray gun 3 is gasified into ammonia gas by high-temperature flue gas, the ammonia gas and nitrogen oxide in the flue gas are subjected to reduction reaction, primary denitration is realized, the denitration efficiency can reach 30% -40%, and the concentration of NOx is reduced to 600mg/Nm3The following.
And 5: the ammonia sprayed by the SNCR system does not participate in the reaction, and the unreacted ammonia gas and the flue gas enter the smoke hoods at the bottoms of the preheating section and the roasting soaking section after passing through the material layers of the preheating section and the roasting soaking section together, and the temperature is reduced to 350 ℃.
Step 6: flue gas exhausted from the smoke hood at the bottom of the preheating section and the roasting soaking section enters the heat regeneration air box 4 to be mixed, and the flue gas in the heat regeneration air box 4 enters the SCR denitration device 8 through the flue.
And 7: an ammonia injection device 6 is arranged on an inlet flue entering the SCR denitration device 8, so that the ammonia injection amount is supplemented, and sufficient reducing agent is provided.
And 8: the static mixer 7 is arranged behind the ammonia injection device 6 on the inlet flue of the SCR denitration device 8, and the ammonia injected by the ammonia injection device 6 is uniformly mixed with the flue gas through the mixing action of the static mixer.
And step 9: SCR denitration device3 layers of catalysts are suitable to be arranged in the device, and the aperture and the type of the catalyst are determined according to the flue gas condition. In the example, the flue gas dust entering the SCR denitration device is less than or equal to 500mg/Nm3The flue gas temperature is 350 ℃, and a 20-hole honeycomb catalyst is selected.
Step 10: the SCR denitration device is provided with a soot blower, and the soot blower can adopt an acoustic wave soot blower or a rake type soot blower and is determined according to parameters such as the temperature of flue gas, the dust content and the like.
Step 11: after the denitration reaction of the flue gas is completed in the SCR denitration device 8, the flue gas is sent to an air draft drying section of the belt type roasting machine through a heat return fan 10.
Step 12: the flue gas finally enters the main air-draft system after passing through the air-draft drying section, and is discharged to a chimney 17 through a main air-draft electric dust collector 12, a desulfurization device 13 and a main exhaust fan 14 in sequence.
Particularly, the ammonia injection amount of the top smoke hood of the preheating section and the roasting soaking section and the ammonia injection amount of the inlet flue of the SCR denitration device 8 in the steps can be manually or automatically adjusted, the ammonia injection amounts are controlled according to the concentration of nitrogen oxides of the emission outlet, the ammonia injection amounts are reasonably distributed, the ammonia injection amounts are reduced to the maximum extent while the emission requirements are met, and the smoke is prevented from generating NH at the low-temperature section at the downstream4HSO4。
Particularly, in order to avoid the adverse effect of wet flue gas and the like generated in the furnace baking stage during the initial operation of the pellet system on the catalyst, a bypass flue and a low-leakage closed air valve 9 are arranged, and an electric air valve 5 is arranged on an inlet flue of the SCR denitration device 8. In the furnace baking stage, the flue gas can directly enter the regenerative fan 10 through the bypass flue by opening the low-leakage closed air valve 9 and closing the electric air valve 5, and does not pass through the SCR denitration device 8. And when the system is normally put into operation, the low-leakage airtight air valve 9 is closed, the electric air valve 5 is opened, and the flue gas enters the regenerative fan 10 after passing through the SCR denitration device 8.
The above-mentioned embodiments are merely illustrative of the present invention, and not restrictive, and any modifications, equivalents, improvements and equivalents which come within the spirit and principle of the present invention are intended to be protected by the following claims.

Claims (6)

1. Embedded SCR + SNCR flue gas denitrification facility of belt roasting machine, its characterized in that: the device comprises an annular air cooler (1), a top flue (2), an SNCR (selective non catalytic reduction) atomizing spray gun (3), a backheating air box (4), an electric air valve (5), an ammonia injection device (6), a static mixer (7), an SCR (selective catalytic reduction) denitration device (8), a low-leakage airtight air valve (9), a backheating air blower (10), a blowing dry air blower (11), a main suction electric dust collector (12), a desulfurization device (13), a main exhaust fan (14), a blowing dry electric dust collector (15), a blowing dry exhaust fan (16) and a chimney (17);
holes are formed on the side walls of the smoke hoods at the tops of the preheating section and the roasting soaking section, and an SNCR (selective non-catalytic reduction) atomizing spray gun (3) is installed; an SCR denitration device (8) is arranged in front of a regenerative fan (10), a regenerative air box (4) is connected with an inlet of the SCR reaction device (8) through a flue, flue gas in the regenerative air box (4) enters the SCR reaction device (8) through the flue, and an ammonia injection device (6) is arranged in the flue at the inlet of the SCR reaction device (8); after the air draft drying section, a main air draft electric dust collector (12), a desulphurization device (13) and a main exhaust fan (14) are connected in sequence and discharged to a chimney (17); an electric air valve (5), an ammonia injection device (6) and a static mixer (7) are sequentially arranged on an inlet flue of an SCR (selective catalytic reduction) denitration device (8), a regenerative fan (10) is arranged on an outlet flue of the SCR denitration device (8), a bypass flue and a low-leakage airtight air valve (9) are arranged on a regenerative air box (4), the bypass flue is connected with the regenerative fan (10), and the other end of the regenerative fan (10) is connected with an air draft drying section; one end of the blast drying section is connected with the cooling second section through a blast blower (11), the other end of the blast drying section is connected with a chimney (17) through a blast electric dust collector (15) and a blast exhaust fan (16) in sequence, the annular air cooler (1) is connected with the top flue (2) through the cooling first section and the cooling second section, and the SNCR atomizing spray gun (3) is positioned in the top flue (2).
2. The embedded SCR + SNCR flue gas denitration method of the belt type roasting machine is characterized in that:
step one, holes are formed in the side walls of top smoke hoods of a preheating section and a roasting soaking section, and SNCR (selective non-catalytic reduction) atomization spray guns (3) are installed and are arranged on two sides of the top smoke hoods of the preheating section and the roasting soaking section;
step two, the SNCR atomization spray gun (3) is provided with a cooling air and atomization air system;
step three, spraying a reducing agent into a smoke hood at the top of the preheating section and the roasting soaking section through an SNCR (selective non-catalytic reduction) atomization spray gun (3);
step four, the reducing agent sprayed by the SNCR atomization spray gun (3) and the nitrogen oxide in the flue gas are subjected to reduction reaction to realize primary denitration;
fifthly, the part of the reducing agent which is sprayed by the SNCR system and does not participate in the reaction and the flue gas pass through the material layers of the preheating section and the roasting soaking section and then enter the smoke hood at the bottom of the preheating section and the roasting soaking section;
sixthly, flue gas exhausted from the smoke hood at the bottom of the preheating section and the roasting soaking section enters a regenerative air box (4) to be mixed, and the flue gas in the regenerative air box (4) enters an SCR (selective catalytic reduction) denitration device (8) through a flue;
step seven, arranging an ammonia injection device (6) on an inlet flue entering the SCR denitration device (8);
step eight, arranging a static mixer (7) behind the ammonia injection device (6) on the inlet flue of the SCR denitration device (8), and uniformly mixing the ammonia injected by the ammonia injection device (6) with the flue gas through the mixing action of the static mixer;
ninth, arranging a catalyst in the SCR denitration device, wherein the aperture and the type of the catalyst are determined according to the flue gas condition;
step ten, the SCR denitration device is provided with a soot blowing device, and the soot blowing device adopts an acoustic wave soot blower or a rake type soot blower;
step eleven, after the denitration reaction of the flue gas in the SCR denitration device (8) is completed, the flue gas is sent into an air draft drying section of the belt type roasting machine through a heat return fan (10);
and step twelve, the flue gas finally enters a main air draft system after passing through an air draft drying section, and is discharged to a chimney (17) through a main air draft dust collector (12), a desulfurization device (13) and a main air draft fan (14) in sequence.
3. The embedded SCR + SNCR flue gas denitration method of a belt-type roasting machine of claim 2, which is characterized in that: the reducing agent is liquid ammonia or ammonia water.
4. The embedded SCR + SNCR flue gas denitration method of a belt-type roasting machine of claim 2, which is characterized in that: the primary denitration is carried out at the reaction temperature of 900-1100 ℃ and has the residence time of not less than 0.3 s.
5. The embedded SCR + SNCR flue gas denitration method of a belt-type roasting machine of claim 2, which is characterized in that: the primary denitration efficiency can reach 30-40%, and the concentration of NOx is reduced to 600mg/Nm3The following.
6. The embedded SCR + SNCR flue gas denitration method of a belt-type roasting machine of claim 2, which is characterized in that: the heat recovery air box (4) is provided with a bypass flue and a low-leakage closed air valve (9), and an electric air valve (5) is arranged on an inlet flue of the SCR denitration device (8); in the furnace baking stage, the flue gas can directly enter the regenerative fan (10) through the bypass flue by opening the low-leakage closed air valve (9) and closing the electric air valve (5) without passing through the SCR denitration device (8); and when the device is normally put into operation, the low-leakage airtight air valve (9) is closed, the electric air valve (5) is opened, and the flue gas enters the air returning machine (10) after passing through the SCR denitration device (8).
CN202110114143.5A 2021-01-27 2021-01-27 Embedded SCR + SNCR flue gas denitration device and method for belt type roasting machine Pending CN112762707A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113802018A (en) * 2021-10-18 2021-12-17 中冶北方（大连）工程技术有限公司 Preparation of V based on a straight grate2O5Pellet system and method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113802018A (en) * 2021-10-18 2021-12-17 中冶北方（大连）工程技术有限公司 Preparation of V based on a straight grate2O5Pellet system and method

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