CN115491452A - Production method for reducing emission concentration of nitrogen oxides in flue gas of blast furnace hot blast stove - Google Patents
Production method for reducing emission concentration of nitrogen oxides in flue gas of blast furnace hot blast stove Download PDFInfo
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 117
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 67
- 239000003546 flue gas Substances 0.000 title claims abstract description 67
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 45
- 238000002485 combustion reaction Methods 0.000 claims abstract description 125
- 239000002912 waste gas Substances 0.000 claims abstract description 64
- 239000003034 coal gas Substances 0.000 claims abstract description 38
- 239000004519 grease Substances 0.000 claims abstract description 27
- 239000007789 gas Substances 0.000 claims description 138
- 230000000087 stabilizing effect Effects 0.000 claims description 15
- 239000000446 fuel Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 12
- 239000002699 waste material Substances 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 11
- 238000007664 blowing Methods 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 3
- 230000000977 initiatory effect Effects 0.000 claims 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 5
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 4
- 239000000779 smoke Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920000515 polycarbonate Polymers 0.000 description 2
- 239000004417 polycarbonate Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B9/00—Stoves for heating the blast in blast furnaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B7/00—Blast furnaces
- C21B7/002—Evacuating and treating of exhaust gases
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B9/00—Stoves for heating the blast in blast furnaces
- C21B9/14—Preheating the combustion air
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/62—Mixing devices; Mixing tubes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/66—Preheating the combustion air or gas
-
- 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
- F27D99/00—Subject matter not provided for in other groups of this subclass
- F27D99/0001—Heating elements or systems
- F27D99/0033—Heating elements or systems using burners
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
Abstract
The invention relates to the technical field of reducing the emission concentration of blast furnace hot blast stove flue gas, in particular to a production method for reducing the emission concentration of nitrogen oxides in the blast furnace hot blast stove flue gas. The combustion-supporting air and the coal gas are respectively introduced into the hot blast stove from different combustion parts, so that the flame temperature distribution is uniform, the coal gas utilization efficiency is improved, the problems of concentration of high-temperature areas and mass production of nitric oxides during combustion are solved, and the generation amount and emission concentration of the nitric oxides are fundamentally reduced. The combustion furnace is arranged and the waste gas grease is sprayed, so that the temperature of combustion-supporting air and coal gas is improved, the coal gas consumption of the hot blast stove is reduced, the low-nitrogen combustion of the combustion furnace is realized, and the production cost of the hot blast stove is reduced; the reasonable utilization of the heat of the flue gas is realized and the emission of nitrogen oxides is reduced through the multiple circulation of the flue gas in the hot blast stove and the combustion furnace. On the premise of not influencing blast furnace production, the problems of large discharge amount of nitrogen oxides and over-standard discharge concentration of the hot blast furnace are completely solved.
Description
Technical Field
The invention relates to the technical field of reducing the emission concentration of blast furnace hot blast stove flue gas, in particular to a production method for reducing the emission concentration of nitrogen oxides in the blast furnace hot blast stove flue gas.
Background
In an iron-making system, a blast furnace hot blast stove generally adopts high-temperature gas generated by burning coal gas to heat and accumulate heat for checker bricks of a regenerator of the hot blast stove, and high-pressure cold air from a blast furnace blower is taken away from high-temperature heat stored in the checker bricks through the regenerator of the hot blast stove during an air supply period and is sent into the blast furnace, so that the high-efficiency and stable production of the hot blast stove is the most basic guarantee for the normal operation of the blast furnace.
As the higher the air temperature of the hot blast stove is, the more beneficial the improvement of the molten iron yield of the blast furnace and the reduction of the fuel consumption are, the development of the steel smelting technology gradually improves the requirement of the blast furnace on the air temperature, the general air temperature of the blast furnace can reach more than 1200 ℃, and the vault temperature of the hot blast stove can reach about 1350 ℃. If the temperature of the hot blast stove is further increased so as to improve the production and benefit indexes of the blast furnace, the vault crown temperature is required to be increasedMeasure of degree, and many research and production practices prove that NO of the hot blast stove x Mainly produced by high-temperature combustion, i.e. N in air 2 By oxidation to NO at high temperatures x After the temperature of the furnace vault of the hot blast is continuously increased to 1400 ℃, NO is added x The generated amount is rapidly increased, so that the concentration of nitrogen oxides in the flue gas can not meet the requirement of environment-friendly ultralow emission, the intergranular stress corrosion of the furnace shell in a high-temperature area can be aggravated, and the service life of the blast furnace hot blast stove is shortened. If the denitration equipment is matched with the hot blast stove, the investment and management cost of the iron making system can be greatly increased and cannot be paid.
Due to NO in the hot blast stove x The generation of the nitrogen oxides is mainly related to the temperature, so the most fundamental measure for reducing the nitrogen oxide emission concentration of the hot blast stove is to reduce the vault temperature of the hot blast stove, but the vault temperature is reduced, the hot blast temperature is reduced, the operation of the blast furnace is seriously influenced, and therefore, a method for effectively reducing the nitrogen oxide generation and emission of the hot blast stove is imperative to be found.
CN201310067318.7 discloses a "self-circulation combustion method and system of flue gas of a blast furnace hot blast stove", in which a part of hot air introduced into the blast furnace is returned and mixed with a part of flue gas discharged outside to be used as combustion-supporting gas of the hot blast stove; because the oxygen content of the combustion-supporting gas is low, the requirement of returned hot air is high, and the stable operation of the blast furnace is seriously influenced. CN202021283819.0 discloses a "flue gas recirculation combustion-supporting air system for direct-fired hot blast stove", reduces the oxygen content of combustion-supporting air by increasing a flue gas regulating valve and a fresh air manual regulating structure to regulate the ratio of fresh air and flue gas quantity, thereby reducing the combustion temperature and finally achieving the effect of reducing the emission of nitrogen oxides; although the method for reducing the oxygen content of the combustion-supporting air is used for realizing the emission reduction of the nitrogen oxides, specific technical measures and indexes of the method are not described in detail, on one hand, the content of the nitrogen oxides in the flue gas can not be reduced effectively, on the other hand, the temperature of the hot blast stove can be seriously influenced, the stable running state of the blast furnace is damaged, and the safe production of the blast furnace is influenced. In the paper, "flue gas circulation heat accumulation type hot blast stove technical discussion", a concept of providing a flue gas circulation heat accumulation type hot blast stove technology is introduced, wherein the emission of flue gas of the hot blast stove is reduced through oxygen-enriched combustion and flue gas circulation, and the generation of nitrogen oxides is reduced through reduction of the proportion of nitrogen; however, the idea is only a theoretical stage, and the vault temperature is increased along with the increase of the oxygen enrichment, which inevitably brings about the rapid increase of the generation speed and the generation amount of the nitrogen oxides, and the emission amount of the flue gas is reduced, so the concentration of the nitrogen oxides in the flue gas is increased to a greater extent. Some of the related patents and technologies introduced above can seriously affect the safe and stable operation of the blast furnace, and some of the related patents and technologies lack practical operability and practicability, and cannot fundamentally solve the problem that the concentration of nitrogen oxides in the hot blast stove exceeds the standard.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a production method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove. The problem of the fundamental nature of nitrogen oxide large amount of productions is solved, under the prerequisite that does not influence blast furnace steady operation, reduction hot-blast furnace flue gas nitrogen oxide's that can be by a wide margin emission concentration, maneuverability and practicality are strong moreover.
In order to achieve the purpose, the invention adopts the following technical scheme:
a production method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove specifically comprises the following steps:
1) Introducing part of hot waste gas discharged to the atmospheric flue pipe into a pressure stabilizing mixer through an exhaust flue gas induced draft fan, introducing combustion-supporting air into the pressure stabilizing mixer through a combustion-supporting fan, mixing part of hot waste gas with the combustion-supporting air in the pressure stabilizing mixer, and introducing the mixed gas into an air preheater;
2) After the mixed gas is preheated by an air preheater, one part of mixed gas directly enters a hot blast stove, and the other part of mixed gas enters a combustion furnace;
3) The waste gas grease of the waste gas grease pipeline is sprayed into the combustion furnace through a pressurizing ejector; introducing the coal gas of the coal gas pipeline into a coal gas preheater, heating by the coal gas preheater and introducing into a combustion furnace; part of high-temperature hot blast furnace waste gas discharged by the hot blast furnace is introduced into the combustion furnace through a high-temperature flue gas induced draft fan;
4) In the combustion furnace, the other part of the mixed gas entering the combustion furnace, waste gas grease, hot gas and part of the waste gas of the high-temperature hot blast stove are combusted together, and the fuel is the waste gas grease and the gas;
5) The flue gas burned by the combustion furnace respectively passes through a gas preheater and an air preheater, enters a main waste gas pipeline and flows to an outer exhaust flue pipe;
6) One part of the mixed gas directly enters the hot blast stove, the mixed gas entering the hot blast stove is divided into two parts, one part of the mixed gas is introduced into the hot blast stove through a combustion starting part, and the other part of the mixed gas is introduced into the hot blast stove at the upper part of the flame combustion direction; the coal gas in the coal gas pipeline is heated by a coal gas preheater and then enters the hot blast stove to be combusted with the mixed gas in the hot blast stove;
7) And after the gas combusted in the hot blast furnace is subjected to blast heat exchange by a blower, the generated high-temperature hot air is finally introduced into the blast furnace for blast furnace production.
The pressure fluctuation of the mixed gas in the step 1) is less than or equal to 0.018MPa, and the oxygen mass percentage content of the mixed gas is 15.5-20.5%.
In the process of mixing part of hot waste gas discharged to the atmospheric flue pipe and combustion air in the step 1), the volume of the waste gas entering an exhaust flue gas induced draft fan accounts for 5-25% of the volume of the final exhaust waste gas, the pressure of the exhaust flue gas induced draft fan is not less than 7500pa, and the temperature of the circulating waste gas is 150-430 ℃.
And 3) introducing the waste gas of the hot blast stove into the combustion furnace through a high-temperature flue gas induced draft fan, wherein the waste gas accounts for 3-17% of the total volume of the waste gas discharged by the hot blast stove.
And 4) respectively carrying out blowing combustion on the waste grease and the coal gas in a combustion furnace, wherein the blowing proportion of the waste grease passing through a pressurizing ejector accounts for 30-80% of the total blowing fuel mass of the combustion furnace, the blowing proportion of the coal gas accounts for 15-75% of the total blowing fuel mass of the combustion furnace, the highest temperature of the combustion furnace is controlled below 1050 ℃, and the temperature of the waste gas of the combustion furnace is not lower than 200 ℃.
And 5) preheating the coal gas and the combustion-supporting air respectively through a coal gas preheater and an air preheater, wherein heat sources of the coal gas preheater and the air preheater are from waste gas generated by a hot blast stove and waste gas generated by a combustion furnace.
And 6) introducing 60-90% of the volume of the mixed gas entering the hot blast stove from the combustion starting part, and introducing 10-40% of the volume of the mixed gas entering the hot blast stove from the upper part in the flame combustion direction.
Compared with the prior art, the invention has the beneficial effects that:
firstly, combustion-supporting air and coal gas are respectively introduced into the hot blast stove from different combustion positions, the traditional combustion mode is changed, the flame length in the hot blast stove is increased on the premise of not reducing the vault temperature of the hot blast stove, the temperature of a flame core is reduced, the flame temperature distribution is uniform, the coal gas utilization efficiency is improved, the problems of concentration of a high-temperature area and mass production of nitric oxides during combustion are solved, and the generation amount and the emission concentration of the nitric oxides are fundamentally reduced.
And secondly, the combustion furnace is arranged and the waste gas grease is sprayed, so that the temperature of combustion-supporting air and coal gas is improved, the coal gas consumption of the hot blast stove is reduced, the low-nitrogen combustion of the combustion furnace is realized, and the production cost of the hot blast stove is reduced.
Thirdly, through the multiple circulation of the flue gas in the hot blast stove and the combustion furnace, the reasonable utilization of the heat of the flue gas is realized, and the emission of nitrogen oxides is reduced.
By the technology, the problems of large discharge amount of nitrogen oxides and over-standard discharge concentration of the hot blast stove are completely solved on the premise of not influencing blast furnace production.
Drawings
FIG. 1 is a schematic view of the production process and structure of the present invention.
In the figure: 1. a chimney; 2. a combustion fan; 3. a pressure stabilizing mixer; 4. an exhaust flue gas induced draft fan; 5. a gas pipeline; 6. a gas preheater; 7. an air preheater; 8. a blower; 9. a combustion furnace; 10. a high-temperature flue gas induced draft fan; 11. a booster ejector; 12. a waste grease pipeline; 13. a hot blast stove; 14. blast furnace
Detailed Description
The invention discloses a production method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove. Those skilled in the art can modify the process parameters appropriately to achieve the desired results with reference to the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations and modifications, or appropriate variations and combinations of the methods and applications described herein may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.
The following examples are provided to further illustrate the invention and are not intended to limit the scope of the invention.
As shown in fig. 1, a system for reducing emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove comprises a chimney 1, a combustion fan 2, a pressure stabilizing mixer 3, an exhaust flue gas induced draft fan 4, a gas pipeline 5, a gas preheater 6, an air preheater 7, a blower 8, a combustion furnace 9, a high temperature flue gas induced draft fan 10, a pressurizing ejector 11, a waste grease pipeline 12, a hot blast stove 13 and a blast furnace 14.
The combustion fan 2 is connected with the pressure stabilizing mixer 3 through a pipeline. The chimney 1, the exhaust flue gas induced draft fan 4 and the pressure stabilizing mixer 3 are sequentially connected through pipelines. The pressure stabilizing mixer 3, the air preheater 7 and the combustion furnace 9 are connected in sequence through pipelines.
The gas pipeline 5, the gas preheater 6, the hot blast stove 13 and the combustion furnace 9 are sequentially connected through pipelines. The air blower 8, the hot blast stove 13 and the combustion furnace 9 are sequentially connected through pipelines, and a high-temperature flue gas induced draft fan 10 is arranged on the pipeline connecting the hot blast stove 13 and the combustion furnace 9. The waste grease pipeline 12, the booster ejector 11 and the combustion furnace 9 are sequentially connected through pipelines. The air preheater 7 is connected with a pipeline of a hot blast stove 13, and the hot blast stove 13 is connected with a pipeline of a blast furnace 14.
The inlet and outlet of the air preheater 7 are provided with valves, the inlet and outlet of the gas preheater 6 are provided with valves, and the inlet of the hot blast stove 13 is provided with a valve.
As shown in fig. 1, a production method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove specifically comprises the following steps:
1) In a blast furnace hot blast stove production system, part of hot waste gas discharged to an atmosphere flue pipe 1 is introduced into a pressure stabilizing mixer 3 through an exhaust flue gas induced draft fan 4, the volume of the waste gas entering the exhaust flue gas induced draft fan 4 accounts for 5-25% of the volume of the final exhaust waste gas, the pressure of the exhaust flue gas induced draft fan is not less than 7500pa, and the temperature of the circulating waste gas is 150-430 ℃.
Combustion-supporting air is introduced into the pressure-stabilizing mixer 3 through the combustion-supporting fan 2, part of hot waste gas is mixed with the combustion-supporting air in the pressure-stabilizing mixer 3, the pressure fluctuation of the mixed gas is less than or equal to 0.018MPa, the oxygen mass percentage content of the mixed gas is 15.5-20.5%, and the mixed gas is introduced into the air preheater 7.
2) The mixed gas is preheated by an air preheater 7, and a part of the mixed gas directly enters a hot blast stove 13. The mixed gas is preheated by an air preheater 7, and the other part of the mixed gas enters a combustion furnace 9.
3) The waste gas grease of waste gas grease pipe 12 is injected into combustion furnace 9 through pressure boosting injector 11. The coal gas of the coal gas pipeline 5 is introduced into a coal gas preheater 6, heated by the coal gas preheater 6 and then introduced into a combustion furnace 9. Part of the high-temperature hot blast furnace waste gas discharged by the hot blast furnace 13 is introduced into the combustion furnace 9 through the high-temperature flue gas induced draft fan 10. The waste gas of the hot blast stove introduced into the combustion furnace 9 by the high-temperature flue gas induced draft fan 10 accounts for 3-17% of the total volume of the waste gas discharged by the hot blast stove.
4) In the combustion furnace 9, the other part of the mixed gas enters the combustion furnace 9, the waste gas grease in an atomized state in the combustion furnace 9 and the hot gas preheated by the gas preheater 6 are sprayed, and the high-temperature flue gas induced draft fan 10 is used for combusting the part of the high-temperature hot blast furnace waste gas which is directly discharged from the hot blast furnace 13 and does not enter the gas preheater 6. The fuel is waste gas grease and coal gas in the combustion process of the combustion furnace.
In the combustion furnace 9, the injection combustion of the waste grease and the gas is respectively carried out, the injection proportion of the waste grease passing through the booster injector 11 accounts for 30-80% of the total injection fuel mass of the combustion furnace, the injection proportion of the gas accounts for 15-75% of the total injection fuel mass of the combustion furnace, the highest temperature of the combustion furnace is controlled below 1050 ℃, and the temperature of the waste gas of the combustion furnace is more than or equal to 200 ℃.
5) The flue gas burned by the combustion furnace respectively passes through a gas preheater 6 and an air preheater 7, enters a waste gas main pipeline and flows to an outer exhaust flue 1. The gas and the combustion air are preheated by a gas preheater 6 and an air preheater 7 respectively, and the heat sources of the gas preheater 6 and the air preheater 7 are from waste gas generated by a hot blast stove 13 and waste gas generated by a combustion furnace 9.
6) The gas in the gas pipeline 5 is heated by the gas preheater 6 and then enters the hot blast stove 16, and is combusted with the mixed gas which is directly fed into the hot blast stove 13 by a part in the step 2) according to a certain proportion. The mixed gas entering the hot blast stove 16 is divided into two parts, the volume of the mixed gas entering the hot blast stove 13 is 60-90% of the volume of the mixed gas entering the combustion starting part, and the mixed gas entering the hot blast stove 13 is 10-40% of the volume of the mixed gas entering the upper part of the flame combustion direction.
7) After the air burned in the hot blast stove 13 is subjected to blast heat exchange by the air blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
[ example 1 ]
In a hot blast stove production system, hot waste gas which is discharged to an atmosphere flue pipe 1 and accounts for 6% of the volume of the final discharged waste gas and has the temperature of 170 ℃ is mixed with air from a combustion fan 2 in a pressure stabilizing mixer 3 through a discharged flue gas induced draft fan 4 with the induced air pressure of 8000pa, the pressure fluctuation of the mixed gas is less than or equal to 0.015MPa, and the oxygen content of the mixed gas is 20.5%.
After being preheated by the air preheater 7, a part of the mixed gas enters the combustion furnace 9, and is combusted together with the waste grease 12 which accounts for 32% of the total injected fuel mass of the combustion furnace 9 and hot gas which is from the gas preheater 6 and accounts for 68% of the total injected mass of the combustion furnace 9, which are sprayed into the combustion furnace 9 through the booster injector 11 and are in an atomized state, and high-temperature hot blast furnace waste gas which is discharged from the hot blast furnace 13, does not enter the gas preheater 6 yet and accounts for 6% of the total volume of the total exhaust gas of the hot blast furnace. The highest temperature of the combustion furnace 9 is 1048 ℃, the temperature of the burned flue gas is 260 ℃, and the part of the flue gas enters the main waste gas pipeline after passing through the coal gas preheater 6 and the air preheater 7 respectively and flows to the outer exhaust flue 1.
The rest of the combustion-supporting mixed gas is directly introduced into the hot blast stove 13, wherein the volume of the mixed gas introduced at the combustion starting part of the hot blast stove accounts for 90 percent of the total volume of the mixed gas, and the volume of the mixed gas introduced at the upper part of the flame combustion direction accounts for 10 percent of the total volume of the mixed gas. The volume of the gas directly introduced into the hot blast stove is 80% of the total volume of the gas entering the hot blast stove at the initial combustion part, and the volume of the gas introduced into the upper part of the flame combustion direction is 20% of the total volume of the gas entering the hot blast stove.
After the hot blast stove after burning is subjected to blast heat exchange by the air blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
Table 1 shows the actual production data of example 1 and comparative example 1 of the present invention
By comparing production data, when the vault temperature of the hot blast stove at 1280 ℃ is not changed, the hot blast temperature is increased by 5 ℃, and through the industrial application of the invention, the concentration of nitrogen oxide can be from 180mg/m 3 Down to 140mg/m 3 The requirement of environmental protection emission is met, and the stable and smooth running of the blast furnace is ensured.
[ example 2 ] A method for producing a polycarbonate
In a hot blast stove production system, hot waste gas which is discharged to an atmospheric flue pipe 1 and accounts for 11% of the volume of the final discharged waste gas and has the temperature of 200 ℃ is mixed with air from a combustion fan 2 in a pressure stabilizing mixer 3 through an induced draft fan 4 with the induced draft pressure of 8500pa, the pressure fluctuation of the mixed gas is less than or equal to 0.016MPa, and the oxygen content of the mixed gas is 18.5%.
The partial mixed gas is preheated by an air preheater 7, one part of the partial mixed gas enters a combustion furnace 9, and is mixed with waste grease 12 which is sprayed into the combustion furnace by a booster injector 11 and accounts for 55% of the total injected fuel mass of the combustion furnace 9, hot gas which is from a gas preheater 6 and accounts for 45% of the total injected mass of the combustion furnace 9, and high-temperature hot blast furnace waste gas which is discharged from a hot blast furnace 13 and does not enter the gas preheater 6 and accounts for 9% of the total volume of the total discharged waste gas of the hot blast furnace are combusted together by a high-temperature smoke induced draft fan 10, the highest temperature of the combustion furnace 9 is 1040 ℃, the temperature of the combusted smoke gas is 350 ℃, and the partial smoke gas enters a waste gas main pipeline after passing through the gas preheater 6 and the air preheater 7 respectively and flows to an outer discharge chimney 1.
The rest of the combustion-supporting mixed gas is directly introduced into the hot blast stove 13, wherein the volume of the mixed gas introduced at the combustion starting part of the hot blast stove accounts for 70 percent of the total volume of the mixed gas, and the volume of the mixed gas introduced at the upper part of the flame combustion direction accounts for 30 percent of the total volume of the mixed gas. The volume of the gas directly introduced into the hot blast stove is 60% of the total volume of the gas entering the hot blast stove at the initial combustion part, and the volume of the gas introduced into the upper part in the flame combustion direction is 40% of the total volume of the gas entering the hot blast stove.
After the hot blast stove after burning is subjected to blast heat exchange by the air blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
Table 2 shows the actual production data of example 2 and comparative example 2 of the present invention
By comparing production data, when the temperature of the vault of the hot blast stove at 1320 ℃ is unchanged, the hot blast temperature is increased by 2 ℃ through the industrial application of the method, and the concentration of nitrogen oxides can be 260mg/m 3 Down to 180mg/m 3 The requirement of environmental protection emission is met, and the stable and smooth running of the blast furnace is ensured.
[ example 3 ] A method for producing a polycarbonate
In a hot blast stove production system, hot waste gas which is discharged to an atmospheric flue pipe 1 and accounts for 23% of the volume of the final discharged waste gas and has the temperature of 370 ℃ is mixed with air from a combustion fan 2 in a pressure stabilizing mixer 3 through an induced draft fan 4 with induced draft pressure of 10000pa, the pressure fluctuation of the mixed gas is less than or equal to 0.018MPa, and the oxygen content of the mixed gas is 15.5%.
The partial mixed gas is preheated by an air preheater 7, one part of the partial mixed gas enters a combustion furnace 9, and is mixed with waste grease 12 which is sprayed into the combustion furnace by a booster injector 11 and accounts for 75% of the total injected fuel mass of the combustion furnace 9, hot gas which is from a gas preheater 6 and accounts for 25% of the total injected fuel mass of the combustion furnace 9, and high-temperature hot blast furnace waste gas which is discharged from a hot blast furnace 13 and does not enter the gas preheater 6 and accounts for 16% of the total volume of the total discharged waste gas of the hot blast furnace are combusted together by a high-temperature smoke induced draft fan 10, the highest temperature of the combustion furnace 9 is 1020 ℃, the temperature of the combusted smoke gas is 370 ℃, and the partial smoke gas enters a waste gas main pipeline after passing through the gas preheater 6 and the air preheater 7 respectively and flows to an outer discharge chimney 1.
The rest of the combustion-supporting mixed gas is directly introduced into the hot blast stove 13, wherein the volume of the mixed gas introduced at the combustion starting part of the hot blast stove accounts for 60 percent of the total volume of the mixed gas, and the volume of the mixed gas introduced at the upper part of the flame combustion direction accounts for 40 percent of the total volume of the mixed gas. The volume of the gas directly introduced into the hot blast stove is 55 percent of the total volume of the gas entering the hot blast stove at the initial combustion part, and the volume of the gas introduced into the upper part of the flame combustion direction is 45 percent of the total volume of the gas entering the hot blast stove.
After the hot blast stove after burning is subjected to blast heat exchange by the air blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
Table 3 shows the actual production data of example 3 and comparative example 3 of the present invention
By comparing production data, when the temperature of the vault of the hot blast stove at 1400 ℃ is not changed, the hot blast temperature is improved by 10 ℃ and the concentration of nitrogen oxides can be increased from 310mg/m by industrial application of the invention 3 The concentration is reduced to 185mg/m 3 The requirement of environmental protection emission is met, and the stable and smooth running of the blast furnace is ensured.
Firstly, combustion-supporting air and coal gas are respectively introduced into the hot blast stove 13 from different combustion parts, the traditional combustion mode is changed, the flame length in the hot blast stove 13 is increased on the premise of not reducing the vault temperature of the hot blast stove 13, the temperature of a flame core is reduced, the flame temperature distribution is uniform, the coal gas utilization efficiency is improved, the problems of concentration of a high-temperature area and mass production of nitric oxides during combustion are solved, and the generation amount and the emission concentration of the nitric oxides are fundamentally reduced.
Secondly, the combustion furnace 9 is arranged and the waste gas grease is sprayed, so that the temperature of combustion-supporting air and coal gas is improved, the coal gas consumption of the hot blast stove 13 is reduced, the low-nitrogen combustion of the combustion furnace 9 is realized, and the production cost of the hot blast stove 13 is reduced.
Thirdly, the reasonable utilization of the heat of the flue gas is realized and the emission of nitrogen oxides is reduced through the multiple circulation of the flue gas in the hot blast stove 13 and the combustion furnace 9.
The invention solves the fundamental problem of the large-scale generation of the nitrogen oxide, can greatly reduce the emission concentration of the nitrogen oxide in the flue gas of the hot blast stove on the premise of not influencing the stable operation of the blast furnace, and has strong operability and practicability.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (7)
1. A production method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove is characterized by comprising the following steps:
1) Introducing part of hot waste gas discharged to an atmosphere flue pipe into a pressure stabilizing mixer through an exhaust flue gas induced draft fan, introducing combustion-supporting air into the pressure stabilizing mixer through a combustion-supporting fan, mixing part of hot waste gas with the combustion-supporting air in the pressure stabilizing mixer, and introducing the mixed gas into an air preheater;
2) After the mixed gas is preheated by an air preheater, one part of mixed gas directly enters a hot blast stove, and the other part of mixed gas enters a combustion furnace;
3) The waste gas grease of the waste gas grease pipeline is sprayed into the combustion furnace through a pressurizing ejector; introducing the coal gas of the coal gas pipeline into a coal gas preheater, heating by the coal gas preheater and introducing into a combustion furnace; part of high-temperature hot blast furnace waste gas discharged by the hot blast furnace is introduced into the combustion furnace through a high-temperature flue gas induced draft fan;
4) In the combustion furnace, the other part of the mixed gas entering the combustion furnace, waste gas grease, hot gas and part of the waste gas of the high-temperature hot blast stove are combusted together, and the fuel is the waste gas grease and the gas;
5) The flue gas burned by the combustion furnace respectively passes through a gas preheater and an air preheater, enters a main waste gas pipeline and flows to an outer exhaust flue pipe;
6) One part of the mixed gas directly enters the hot blast stove, the mixed gas entering the hot blast stove is divided into two parts, one part of the mixed gas is introduced into the hot blast stove through a combustion starting part, and the other part of the mixed gas is introduced into the hot blast stove at the upper part of the flame combustion direction; the coal gas in the coal gas pipeline is heated by a coal gas preheater and then enters the hot blast stove to be combusted with the mixed gas in the hot blast stove;
7) After the air combusted in the hot blast furnace is subjected to blast heat exchange by a blower, the generated high-temperature hot air is finally introduced into the blast furnace for blast furnace production.
2. The production method for reducing the emission concentration of nitrogen oxides in flue gas of the blast furnace hot blast stove according to claim 1, wherein the pressure fluctuation of the mixed gas in the step 1) is less than or equal to 0.018MPa, and the oxygen content of the mixed gas is 15.5-20.5% by mass.
3. The production method for reducing the emission concentration of nitrogen oxides in flue gas of the blast furnace hot blast stove according to claim 1, wherein in the process of mixing part of the hot exhaust gas discharged to the atmospheric flue pipe in the step 1) with combustion air, the volume of the exhaust gas entering the discharged flue gas induced draft fan accounts for 5-25% of the volume of the final discharged exhaust gas, the pressure of the discharged flue gas induced draft fan is not less than 7500pa, and the temperature of the circulating exhaust gas is 150-430 ℃.
4. The production method for reducing the emission concentration of nitrogen oxides in flue gas of the blast furnace hot blast stove according to claim 1, wherein the exhaust gas of the hot blast stove introduced into the combustion furnace by the high-temperature flue gas induced draft fan in the step 3) accounts for 3-17% of the total volume of the exhaust gas discharged from the hot blast stove.
5. The production method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove according to claim 1, wherein the step 4) comprises respectively carrying out blowing combustion on waste grease and gas in a combustion furnace, wherein the blowing proportion of the waste grease after passing through a pressurizing injector accounts for 30-80% of the total blowing fuel mass of the combustion furnace, the blowing proportion of the gas accounts for 15-75% of the total blowing fuel mass of the combustion furnace, the maximum temperature of the combustion furnace is controlled below 1050 ℃, and the temperature of exhaust gas of the combustion furnace is not lower than 200 ℃.
6. The method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove according to claim 1, wherein the step 5) gas and combustion air are preheated by a gas preheater and an air preheater respectively, and heat sources of the gas preheater and the air preheater are derived from waste gas generated by the hot blast stove and waste gas generated by a combustion furnace.
7. The method for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove according to claim 1, wherein the combustion initiation part of step 6) is introduced into the hot blast stove by 60-90% of the volume of the mixture gas entering the hot blast stove, and the mixture gas entering the hot blast stove is introduced into the upper part of the flame combustion direction by 10-40% of the volume of the mixture gas entering the hot blast stove.
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