CN117249691A - Sintering flue gas circulating purification emission reduction process and system - Google Patents
Sintering flue gas circulating purification emission reduction process and system Download PDFInfo
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- CN117249691A CN117249691A CN202311405024.0A CN202311405024A CN117249691A CN 117249691 A CN117249691 A CN 117249691A CN 202311405024 A CN202311405024 A CN 202311405024A CN 117249691 A CN117249691 A CN 117249691A
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- sintering
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- air box
- flue
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- 238000005245 sintering Methods 0.000 title claims abstract description 165
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 160
- 239000003546 flue gas Substances 0.000 title claims abstract description 150
- 238000000746 purification Methods 0.000 title claims abstract description 16
- 238000011946 reduction process Methods 0.000 title claims abstract description 8
- 239000000779 smoke Substances 0.000 claims abstract description 78
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 238000002485 combustion reaction Methods 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 14
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910002091 carbon monoxide Inorganic materials 0.000 claims abstract description 10
- 230000001502 supplementing effect Effects 0.000 claims abstract description 10
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 238000007599 discharging Methods 0.000 claims abstract description 3
- 239000000428 dust Substances 0.000 claims description 27
- 229910052760 oxygen Inorganic materials 0.000 claims description 19
- 239000001301 oxygen Substances 0.000 claims description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- 238000009826 distribution Methods 0.000 claims description 9
- 125000004122 cyclic group Chemical group 0.000 claims description 3
- 239000003344 environmental pollutant Substances 0.000 abstract description 30
- 231100000719 pollutant Toxicity 0.000 abstract description 19
- 230000000694 effects Effects 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 239000002918 waste heat Substances 0.000 description 6
- 238000009766 low-temperature sintering Methods 0.000 description 5
- 238000006477 desulfuration reaction Methods 0.000 description 4
- 230000023556 desulfurization Effects 0.000 description 4
- 239000000446 fuel Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- 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
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
- F23B80/00—Combustion apparatus characterised by means creating a distinct flow path for flue gases or for non-combusted gases given off by the fuel
- F23B80/02—Combustion apparatus characterised by means creating a distinct flow path for flue gases or for non-combusted gases given off by the fuel by means for returning flue gases to the combustion chamber or to the combustion zone
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
- F23L7/007—Supplying oxygen or oxygen-enriched air
-
- 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
-
- 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
- F27D19/00—Arrangements of controlling devices
-
- 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
- F27D19/00—Arrangements of controlling devices
- F27D2019/0006—Monitoring the characteristics (composition, quantities, temperature, pressure) of at least one of the gases of the kiln atmosphere and using it as a controlling value
- F27D2019/0012—Monitoring the composition of the atmosphere or of one of their components
- F27D2019/0015—Monitoring the composition of the exhaust gases or of one of its components
Abstract
The invention discloses a circulating purification emission reduction process of sintering flue gas and a corresponding emission reduction system, wherein the flue gas in 2-4 bellows at the rear part of a sintering machine is mixed to obtain high-temperature mixed flue gas, and the high-temperature mixed flue gas is fed with pure oxygen and then is led into an igniter of the sintering machine for combustion supporting; mixing the smoke in a plurality of bellows with carbon monoxide concentration larger than a first preset value in the bellows at the front part of the sintering machine to obtain low-temperature mixed smoke, heating the low-temperature mixed smoke to obtain heating mixed smoke, supplementing pure oxygen into the heating mixed smoke, and discharging the heating mixed smoke above a sintering machine material layer for combustion. The method can effectively reduce the concentration of pollutants such as carbon monoxide in sintering flue gas, lighten the load of a flue purifying treatment system and has good environmental protection effect.
Description
Technical Field
The invention relates to the field of treatment of CO in sintering flue gas, in particular to a process and a system for circularly purifying and reducing emission of sintering flue gas.
Background
The sintering flue gas contains high concentration pollutants such as SOx, NOx, VOC and dioxin, and the distribution of the pollutants in the length direction of the sintering machine is uneven, namely the content of the pollutants in each bellows in the length direction of the sintering machine is different. In general, the sinters end with a low level of windbox contaminants and a relatively high flue gas temperature and a certain amount of waste heat. At present, the actual sintering production adopts flue gas circulation to realize reduction of sintering pollutants. However, the method circulates one part of the whole sintering flue gas, and the other part is discharged, so that the effect of purifying and reducing the emission is not ideal, the pollutant discharge amount is still higher, and the burden on an environment-friendly treatment system (only capable of removing dust, desulfurizing and denitrating) of the main flue is excessive. For example, the current sintering flue gas circulation process can only make the concentration of CO in the sintering flue gas from 9000 to 12000mg/Nm 3 Reduce the dosage to 6000-8000mg/Nm 3 Nationwide sintering machine systemThe annual CO emissions are still up to 800 hundred million Nm in the form of blast furnace gas 3 About, not only seriously pollute the environment, but also waste a large amount of high-quality energy.
In view of this, there is a need to further improve the purification and emission reduction process of sintering flue gas to reduce the emission of pollutants and improve the energy utilization.
Disclosure of Invention
The invention aims to provide a recycling purification and emission reduction process for sintering flue gas, which can effectively reduce the concentration of pollutants such as carbon monoxide and the like in the sintering flue gas, lighten the load of a flue purification treatment system and has good environmental protection effect.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a sintering flue gas circulation purification emission reduction process comprises the following steps:
step S1: mixing the smoke in the 2-4 bellows at the rearmost part of the sintering machine to obtain high-temperature sintering circulating smoke, supplementing pure oxygen into the high-temperature sintering circulating smoke, and introducing the high-temperature sintering circulating smoke into an igniter of the sintering machine for combustion supporting;
step S2: mixing the smoke in a plurality of bellows with carbon monoxide concentration larger than a first preset value in the front bellows of the sintering machine to obtain low-temperature mixed smoke, heating the low-temperature mixed smoke to obtain heating mixed smoke, supplementing pure oxygen into the heating mixed smoke, and discharging the heating mixed smoke above a sintering machine material layer for combustion; and heating the low-temperature mixed flue gas by adopting the high-temperature sintering circulating flue gas and/or the hot air of the circular cooler.
Preferably, in the step S2, sintering flue gas of a plurality of bellows in a front bellows of the sintering machine is exhausted into the atmosphere, and the plurality of bellows exhausted into the atmosphere includes a second bellows and a plurality of intermediate front bellows sequentially arranged backwards from the second bellows; the front air box of the sintering machine comprises a first air box, a second middle air box and a rear air box, wherein the first air box, the second middle air box and the rear air box are arranged in sequence, the second middle air box comprises a last air box connected with a first large flue and a rest middle air box which is arranged backwards in sequence and is a last air box connected with the first large flue, and the rear air box comprises an air box between the second middle air box and the last 2-4 air boxes.
Further preferably, in the step S2, the high-temperature sintering circulating flue gas of the 2-4 air boxes at the rear part of the sintering machine is led out in two ways after being mixed and collected, one way is directly mixed with the flue gas in the air boxes with the carbon monoxide concentration larger than the first preset value in the air boxes at the front part of the sintering machine to form low-temperature mixed flue gas, and the other way is led into the igniter of the sintering machine for combustion supporting after pure oxygen is supplemented.
The invention also aims to provide an emission reduction system for realizing the method, which concretely adopts the following scheme:
the sintering flue gas circulation purification and emission reduction system comprises a sintering machine, wherein an ignition furnace is arranged on the sintering machine, an ignition furnace nozzle is arranged on the ignition furnace, a machine top smoke hood is arranged on the upper part of the sintering machine, a machine top flue gas distribution pipe is arranged on the machine top smoke hood and is connected with a circulation pipeline, a plurality of air boxes are arranged on the lower part of the sintering machine, the rearmost 2-4 air boxes are connected with a fourth large flue, a plurality of air boxes in the middle are connected with a second large flue and a third large flue, the second large flue is communicated with the third large flue, a plurality of air boxes in the middle are connected with a first large flue, the first large flue is connected with a main smoke exhaust chimney, and the second large flue and the third large flue are connected with a sintering circulation low-temperature flue gas dust remover through smoke exhaust pipelines; the fourth large flue is connected with a sintering circulation low-temperature flue gas dust remover through a first branch pipeline, the sintering circulation low-temperature flue gas dust remover is connected with the circulation pipeline through a heat exchanger, and a first oxygen supplementing device is arranged on the circulation pipeline; the fourth large flue is further connected with the heat exchanger through a second branch pipeline and then connected with the nozzle of the ignition furnace, the sintering circulating low-temperature flue gas dust remover is connected with the heat exchanger through a pipeline, and the second large flue and the third large flue are connected with the main exhaust chimney in an openable and closable mode.
Preferably, the first large flue is connected with a second air box and a plurality of middle front air boxes which are sequentially and backwardly arranged by the second air box, the second large flue is connected with the first air box and a middle second air box, and the middle second air box comprises a remaining middle air box which is sequentially and backwardly arranged by the last air box of the last air box connected with the first large flue and the last air box of the last air box connected with the first large flue; the third large flue is connected with a rear air box, and the rear air box comprises an air box between a second middle air box and a last 2-4 air boxes.
Preferably, the sintering circulation low-temperature flue gas dust remover is connected with the circulation low-temperature flue gas primary heater, the circulation low-temperature flue gas primary heater is connected with the sintering circulation low-temperature flue gas secondary heater, and the sintering circulation low-temperature flue gas secondary heater is connected with the top flue gas distribution pipe through a circulation pipeline.
Further preferably, the sintering cycle low-temperature flue gas primary heater heat source is from circular cooler hot air.
According to the invention, a plurality of bellows in the middle of the sintering machine are subjected to dust removal, heating and oxygen supplementing and then are circulated for the material layer of the sintering machine, so that sintering circulating smoke of a rear bellows in the middle bellows with relatively high concentration of pollutants and carbon monoxide can be led to the upper part of the material layer of the sintering machine to be burnt for use to a greater extent, low-temperature high-pollutant smoke is fully recycled, high-temperature high-oxygen low-pollutant smoke of 2-4 bellows at the tail is respectively used for heating low-temperature smoke and ignition combustion supporting, and sintering smoke in bellows with relatively low concentration of pollutants and carbon monoxide is discharged into the atmosphere after dust removal, desulfurization and denitration, thus the sintering smoke of each bellows is reasonably utilized or reasonably discharged, the circulating quantity of the high-temperature low-pollutant smoke is reduced, the circulating quantity of the low-temperature high-pollutant smoke is correspondingly increased, and finally the reduction of the emission of the smoke pollutants is realized.
Drawings
FIG. 1 is a schematic diagram of a sintering flue gas emission reduction system.
Detailed Description
The following description will be made with reference to two aspects of a process for recycling and purifying sintering flue gas and an emission reduction system for realizing the process by means of specific embodiments, in which the following example 1 describes a method as a main line, while considering a system for realizing the method, and in which the example 2 describes a specific embodiment of the present invention with a method implemented while considering an emission reduction system as a main line, and the two supplements each other.
Example 1 sintering flue gas circulation purification and emission reduction Process
The raw materials for sintering are distributed on a sintering machine 7 after being mixed and granulated, ignition is finished in an ignition furnace 8 firstly, then the raw materials move backwards along with a grate of the sintering machine, and the whole sintering process is finished when the raw materials leave the tail of the sintering machine 7. In the sintering process, the oxidizing gas required for fuel combustion is supplied from the upper part of the material surface and combusts the fuel in the material layer, and the burned sintering flue gas flows downwards into the sintering machine bellows 6. The sintering machine bellows 6 has a plurality of bellows 6 and are distributed along the length direction of the sintering machine 7 in a separated manner, in general, the oxygen content in the sintering flue gas in the first bellows and the last bellows is the highest, the oxygen content is close to the oxygen content in the air, the oxygen content in the sintering flue gas of the rest bellows positioned in the middle is lower, and the volume percentage of the oxygen is 12-15%. The sintering flue gas temperature in the last bellows is higher, up to 200-400 ℃, and the sintering flue gas temperature of the rest bellows is lower, generally lower than 100 ℃. In addition, the concentration of pollutants contained in sintering flue gas is different among the air boxes, the concentration of pollutants contained in the rear air box in the middle air box is high, and the concentration of pollutants contained in the first air box and the last air box is low. Under the action of the suction force of the sintering main smoke exhaust induced draft fan 20, most of low-temperature sintering circulating smoke in the first large smoke flue 3, the second large smoke flue 4 and the third large smoke flue 13 enters the sintering main smoke exhaust flue, and then is dedusted through the sintering main smoke exhaust dedusting system 23, desulfurized through the sintering main smoke exhaust desulfurization system 22, denitrified through the sintering main smoke exhaust denitration system 21 and finally exhausted into the atmosphere through the sintering main smoke exhaust chimney 19. Wherein the low temperature sintering cycle flue gas in the first large flue 3 is taken from the second windbox 62 and several intermediate forward windboxes 51 arranged sequentially rearward from the second windbox 62, the low temperature sintering cycle flue gas in the second large flue 4 is taken from the first windbox 61 and intermediate second windbox 52, the intermediate second windbox 52 comprising the remaining intermediate windbox 55 arranged sequentially rearward from the last windbox 54 of the last windbox 53 connected to the first large flue 3 and from the last windbox 54 of the last windbox 53 connected to the first large flue 3. The low temperature sintering cycle flue gas of the third large flue 13 is taken from the back wind box 56, the back wind box 56 comprising wind boxes between the middle wind box two 52 and the last 2-4 wind boxes 58.
Finally, the high-temperature sintering circulating smoke of the 2-4 bellows 58 is firstly collected in the fourth large flue 14, then is led out in two paths, one path of the high-temperature sintering circulating smoke is directly mixed with the low-temperature mixed smoke (especially the low-temperature sintering circulating smoke led out from the second large flue 4 and the third large flue 13) to form mixed circulating smoke, the mixed circulating smoke enters the sintering circulating low-temperature smoke dust remover 12 to remove dust, the other path of the high-temperature sintering circulating smoke enters the sintering circulating low-temperature smoke secondary heater 18 to carry out secondary temperature raising on the mixture of the low-temperature mixed smoke led out from the second large flue 4 and the third large flue 13 and the other path of high-temperature sintering circulating smoke, namely the mixed circulating smoke, then the pure oxygen is fed in to adjust the oxygen concentration, finally, the mixture enters the ignition furnace burner 9 to be combustion-supporting gas after being pressurized by the high-oxygen sintering circulating fan 2, because the oxygen content required by the fuel combustion process is higher (not the total amount) when the ignition furnace burner 9 is ignited instantaneously, the higher the combustion-supporting temperature is, the easier the ignition of the ignition furnace burner 9 is realized, so that the ignition combustion-supporting of the ignition furnace burner 9 can be better realized by more pertinently extracting the high-temperature sintering circulating flue gas of the last 2-4 bellows (the oxygen content is higher and the temperature is higher), the high-temperature low-pollutant flue gas of the last 2-4 bellows is more reasonably utilized, the high-temperature sintering circulating flue gas enters the sintering circulating low-temperature flue gas secondary heater 18 to carry out secondary temperature raising on the mixed circulating flue gas, the waste heat of the high-temperature low-pollutant flue gas is further utilized, one path of high-temperature sintering circulating flue gas is mixed with the low-temperature mixed flue gas led out by the second large flue 4 and the third large flue 13 with higher carbon monoxide content, the circulating quantity of the high-temperature low-pollutant flue gas is reduced, and the mixed circulating flue gas is heated to a greater extent.
Extracting part of flue gas from the second large flue 4 and the third large flue 13 according to a certain ratio to form low-temperature mixed flue gas with the pollutant concentration and oxygen concentration meeting the requirements, wherein the low-temperature mixed flue gas firstly enters the sintering circulation low-temperature flue gas dust remover 12 to remove dust and then enters the sintering circulation low-temperature flue gas primary heater 17 and the sintering circulation low-temperature flue gas secondary heater 18 to sequentially heat, and the heat source of the sintering circulation low-temperature flue gas primary heater 17 is from hot air of a circular cooler, particularly hot air of a first section to a third section of the circular cooler. The sintering low-temperature circulating flue gas is heated by two stages to form sintering preheating circulating flue gas, and then enters a top flue gas distribution pipe 11 after pure oxygen is regulated, and finally enters a top flue gas hood 10 to be distributed above the sintering material surface.
Example 2 sintering flue gas circulation purification emission reduction System
Referring to fig. 1, the system for circularly purifying and reducing emission of sintering flue gas comprises a sintering machine 7, wherein an ignition furnace 8 is arranged at one end of the sintering machine 7, an ignition furnace burner 9 is arranged on the ignition furnace 8, a top hood 10 is arranged at the upper part of the sintering machine 7, a top flue gas distribution pipe 11 is arranged on the top hood 10, and circulating flue gas enters the top hood 10 through the top flue gas distribution pipe 11 and then burns together with fuel of a material layer of the sintering machine 7. A plurality of bellows 6 are arranged at the lower part of the sintering machine, and flue gas generated by the combustion of the material layer of the sintering machine enters each bellows 6. In this example, there are 30 windboxes in total, and the three windboxes (the 1 st to 3 rd windboxes) at the rearmost part of the sintering machine 7 are connected to the fourth large flue 14, where the flue gas temperature is high and the pollutant content is low. The 1 st and the 4-13 th (i.e., the first windbox 61 and the second middle windbox 52, the second middle windbox 52 includes the remaining middle windbox 55 sequentially arranged rearward from the last windbox 54 of the last windbox 53 connected to the first large flue 3 and from the last windbox 54 of the last windbox 53 connected to the first large flue 3), the second large flue 4 and the third large flue 13 are connected, the second large flue 4 is connected to the third large flue 13, and the 2-17 th windbox (i.e., the second windbox 62 and the middle forward windbox 51 sequentially arranged rearward from the second windbox 62) is connected to the first large flue 3. The fourth large flue 14 is connected with the sintering circulating low-temperature flue gas dust remover 12 through a first branch pipeline 41, is also connected with the low-temperature mixed flue gas secondary heater 18 through a second branch pipeline 42, and the sintering high-temperature circulating flue gas dust remover 16 is arranged on the second branch pipeline 42. The low-temperature mixed flue gas in the second large flue 4 and the third large flue 13 is mixed and then is connected with the sintering circulating low-temperature flue gas dust remover 12 through a smoke inlet and outlet pipeline 43 and a valve 44, the sintering circulating low-temperature flue gas dust remover 12 is connected with the circulating low-temperature flue gas primary heater 17, the circulating low-temperature flue gas primary heater 17 is connected with the sintering circulating low-temperature flue gas secondary heater 18, the sintering circulating low-temperature flue gas secondary heater 18 is connected with the machine top flue gas distributing pipe 11 through a circulating pipeline 45, a pure oxygen supplementing device and a sintering flue gas circulating fan 15 are arranged on the circulating pipeline 45, so that the low-temperature mixed flue gas exhausted from the second large flue 4 and the third large flue 13 is supplemented with pure oxygen after being dedusted through the sintering circulating low-temperature flue gas dust remover 12, heated through the circulating low-temperature flue gas primary heater 17 and reheated through the sintering circulating low-temperature flue gas secondary heater 18, has higher temperature and sufficient oxygen, and then the machine top flue gas distributing pipe 11 and the machine top flue gas hood 10 are used for supporting combustion and combustion in a sintering machine material layer. In this way, the flue gas in the middle bellows 6 with high pollutant content is recycled relatively independently, namely, the recycling rate of the flue gas with high pollutant content is improved, and the emission of the flue gas to the outside is reduced, so that the effect of purifying and reducing emission is achieved.
The high-temperature low-pollutant flue gas from the fourth large flue 14 is mixed with the low-temperature high-pollutant flue gas discharged from the second large flue 4 and the third large flue 13 in the sintering circulation low-temperature flue gas dust remover 12 after passing through the first branch pipeline 41, so that the temperature and the oxygen concentration of the low-temperature high-pollutant flue gas are improved, and the mixed circulation flue gas is formed, and the waste heat of the high-temperature flue gas in the first branch pipeline 41 is utilized. The valve 46 is arranged on the first branch pipeline 41, so that the amount of the mixed low-temperature mixed smoke of the high-temperature smoke through the first branch pipeline 41 can be adjusted, and the amount of the mixed high-temperature smoke can be distributed according to the specific temperature of the low-temperature mixed smoke, so that the temperature of the mixed circulating smoke generated by the sintering circulating low-temperature smoke dust remover 12 is more in line with the expected range, and the mixed circulating smoke is favorably heated to the proper temperature after passing through the circulating low-temperature smoke primary heater 17 and the sintering circulating low-temperature smoke secondary heater 18 for the combustion supporting and burning of the sintering machine material layer.
The high-temperature low-pollutant flue gas from the fourth large flue 14 is fed with pure oxygen by the second oxygen supplementing device after passing through the second branch pipeline 42, the sintering high-temperature circulating flue gas dust remover 16 and the sintering circulating low-temperature flue gas secondary heater 18, and then enters the ignition furnace burner 9 of the ignition furnace 8 through the high-oxygen sintering flue gas circulating fan 2 for igniting the material layer. In this way, the high-temperature flue gas from the second branch pipeline 42 is finally dedusted, heated and supplemented with oxygen and then used for ignition, and the characteristics of high temperature and low pollutant when the part of flue gas comes out of the fourth large flue 14 are just utilized, so that the waste heat contained in the flue gas is fully utilized, and meanwhile, the high-temperature flue gas coming out of the second branch pipeline is reasonably utilized, so that the cyclic utilization rate of the low-temperature high-pollution flue gas coming out of the second large flue 4 and the third large flue 13 is improved under the condition of not generating additional cost.
And part of the flue gas from the middle bellows 6 is directly discharged into the first large flue 3, and then the flue gas is discharged into the atmosphere from the first large flue 3 through the main flue gas exhaust pipeline 47, the main sintering flue gas dust removal system 23 for dust removal, the main sintering flue gas desulfurization system 22 for desulfurization, the main sintering flue gas denitration system 21 for denitration and the main sintering flue gas induced draft fan 20, and finally through the main sintering flue gas chimney 19. The second large flue 4 and the third large flue 13 are also connected with the main smoke exhaust pipeline 47 in an openable and closable manner, and when the low-temperature high-temperature smoke volume in the second large flue 4 and the third large flue 13 is too large to exceed the requirement of the sintering machine material layer, redundant low-temperature high-temperature smoke can be discharged into the main flue 47.
A main flue heat exchanger 1 is also provided on the main flue 47 for recovering the waste heat of the flue gas. Meanwhile, the heat source of the circulating low-temperature flue gas primary heater 17 can come from hot air of the annular cooler, especially one section to three sections of the annular cooler, and redundant hot air of the annular cooler (namely four sections and five sections of the annular cooler and one section to three sections of the annular cooler after heat exchange) enters the hot blast stove after being subjected to waste heat recovery through the main flue heat exchanger 1.
The above embodiments are merely illustrative of the inventive concept and implementation and are not limiting, but the technical solutions without substantial transformation remain within the scope of protection under the inventive concept.
Claims (7)
1. The circular purification and emission reduction process for sintering flue gas is characterized by comprising the following steps of:
step S1: mixing the smoke in the 2-4 bellows at the rearmost part of the sintering machine to obtain high-temperature sintering circulating smoke, supplementing pure oxygen into the high-temperature sintering circulating smoke, and introducing the high-temperature sintering circulating smoke into an igniter of the sintering machine for combustion supporting;
step S2: mixing the smoke in a plurality of bellows with carbon monoxide concentration larger than a first preset value in the front bellows of the sintering machine to obtain low-temperature mixed smoke, heating the low-temperature mixed smoke to obtain heating mixed smoke, supplementing pure oxygen into the heating mixed smoke, and discharging the heating mixed smoke above a sintering machine material layer for combustion; and heating the low-temperature mixed flue gas by adopting the high-temperature sintering circulating flue gas and/or the hot air of the circular cooler.
2. The process for the cyclic purification and emission reduction of sintering flue gas according to claim 1, wherein in the step S2, the sintering flue gas of a plurality of windboxes in the front windbox of the sintering machine is discharged into the atmosphere, and the plurality of windboxes discharged into the atmosphere comprise a second windbox and a plurality of middle front windboxes which are sequentially and backwardly arranged by the second windbox; the front air box of the sintering machine comprises a first air box, a second middle air box and a rear air box, wherein the first air box, the second middle air box and the rear air box are arranged in sequence, the second middle air box comprises a last air box connected with a first large flue and a rest middle air box which is arranged backwards in sequence and is a last air box connected with the first large flue, and the rear air box comprises an air box between the second middle air box and the last 2-4 air boxes.
3. The process for circularly purifying and reducing emission of sintering flue gas according to claim 2, wherein in the step S2, the high-temperature sintering circulating flue gas of the 2-4 windboxes at the rearmost part of the sintering machine is led out in two ways after being mixed and collected, one way is directly mixed with the flue gas in a plurality of windboxes with carbon monoxide concentration larger than a first preset value in the windboxes at the front part of the sintering machine to form low-temperature mixed flue gas, and the other way is led into an igniter of the sintering machine for combustion supporting after pure oxygen is supplemented.
4. The sintering flue gas circulation purification and emission reduction system comprises a sintering machine, and is characterized in that an ignition furnace is arranged on the sintering machine, an ignition furnace nozzle is arranged on the ignition furnace, a machine top smoke hood is arranged on the upper part of the sintering machine, a machine top flue gas distribution pipe is arranged on the machine top smoke hood, the machine top flue gas distribution pipe is connected with a circulation pipeline, a plurality of bellows are arranged on the lower part of the sintering machine, the rearmost 2-4 bellows are connected with a fourth large flue, a plurality of bellows in the middle are connected with a second large flue and a third large flue, the second large flue is communicated with the third large flue, a plurality of bellows in the middle are connected with a first large flue, the first large flue is connected with a main smoke exhaust chimney, and the second large flue and the third large flue are connected with a sintering circulation low-temperature flue gas dust remover through a smoke exhaust pipeline; the fourth large flue is connected with a sintering circulation low-temperature flue gas dust remover through a first branch pipeline, the sintering circulation low-temperature flue gas dust remover is connected with the circulation pipeline through a heat exchanger, and a first oxygen supplementing device is arranged on the circulation pipeline; the fourth large flue is further connected with the heat exchanger through a second branch pipeline and then connected with the nozzle of the ignition furnace, the sintering circulating low-temperature flue gas dust remover is connected with the heat exchanger through a pipeline, and the second large flue and the third large flue are connected with the main exhaust chimney in an openable and closable mode.
5. The system for the cyclic purification and emission reduction of sintering flue gas according to claim 4, wherein the first large flue is connected with a second air box and a plurality of middle front air boxes which are sequentially arranged backwards by the second air box, the second large flue is connected with the first air box and a middle second air box, and the middle second air box comprises a residual middle air box which is sequentially arranged backwards by the air box behind the last air box connected with the first large flue and the air box behind the last air box connected with the first large flue; the third large flue is connected with a rear air box, and the rear air box comprises an air box between a second middle air box and a last 2-4 air boxes.
6. The sintering flue gas circulating purification and emission reduction system according to claim 5, wherein the sintering circulating low-temperature flue gas dust remover is connected with a circulating low-temperature flue gas primary heater, the circulating low-temperature flue gas primary heater is connected with a sintering circulating low-temperature flue gas secondary heater, and the sintering circulating low-temperature flue gas secondary heater is connected with a machine top flue gas distribution pipe through a circulating pipeline.
7. The sintering flue gas circulating purification and emission reduction system as set forth in claim 6, wherein the sintering circulating low temperature flue gas primary heater heat source is from circular cooler hot air.
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