CN115491452B - 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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- CN115491452B CN115491452B CN202211046216.2A CN202211046216A CN115491452B CN 115491452 B CN115491452 B CN 115491452B CN 202211046216 A CN202211046216 A CN 202211046216A CN 115491452 B CN115491452 B CN 115491452B
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 129
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 239000003546 flue gas Substances 0.000 title claims abstract description 62
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 47
- 239000007789 gas Substances 0.000 claims abstract description 150
- 238000002485 combustion reaction Methods 0.000 claims abstract description 132
- 239000002912 waste gas Substances 0.000 claims abstract description 64
- 239000004519 grease Substances 0.000 claims abstract description 27
- 230000000087 stabilizing effect Effects 0.000 claims description 17
- 239000000446 fuel Substances 0.000 claims description 15
- 238000002347 injection Methods 0.000 claims description 15
- 239000007924 injection Substances 0.000 claims description 15
- 239000000779 smoke Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 10
- 239000001301 oxygen Substances 0.000 claims description 10
- 229910052760 oxygen Inorganic materials 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 4
- 239000003034 coal gas Substances 0.000 abstract description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 5
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 4
- 238000005507 spraying Methods 0.000 abstract description 3
- 239000002699 waste material Substances 0.000 description 10
- 238000007664 blowing Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005338 heat storage Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
Landscapes
- 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 flue gas of a blast furnace hot blast stove, in particular to a production method for reducing the emission concentration of nitrogen oxides in flue gas of the blast furnace hot blast stove. Combustion-supporting air and coal gas are respectively introduced into the hot blast stove from different combustion positions, so that flame temperature distribution is uniform, the utilization efficiency of the coal gas is improved, the problems of concentrated high-temperature areas and mass production of nitrogen oxides during combustion are solved, and the production amount and emission concentration of the nitrogen oxides are fundamentally reduced. By arranging the combustion furnace and spraying waste gas grease, the temperature of combustion-supporting air and gas is improved, the 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; through multiple circulation of the flue gas in the hot blast stove and the combustion furnace, reasonable utilization of the heat of the flue gas is realized, and emission of nitrogen oxides is reduced. On the premise of not influencing the production of the blast furnace, the problems of large emission of nitrogen oxides and exceeding of emission 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 flue gas of a blast furnace hot blast stove, in particular to a production method for reducing the emission concentration of nitrogen oxides in flue gas of the blast furnace hot blast stove.
Background
In an iron-making system, high-temperature gas generated by burning coal gas is generally adopted by a blast furnace hot blast stove to heat and store heat for checker bricks of a heat storage chamber of the hot blast stove, and high-pressure cold air from a blast furnace blower is taken away by the high-pressure cold air from the blast furnace blower through the heat storage chamber of the hot blast stove to be sent into the blast furnace in an air supply period, 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.
The higher the air temperature of the hot blast furnace is, the more beneficial is to improving the iron water yield of the blast furnace and reducing the fuel consumption, so with the development of steel smelting technology, the requirements of the blast furnace on the air temperature are gradually improved, the air temperature of the common blast furnace can reach more than 1200 ℃, and the vault temperature of the hot blast furnace can reach about 1350 ℃. If the temperature of the hot blast stove is further increased, and the production and benefit index of the blast furnace are further improved, measures for increasing the temperature of the vault are needed, and many researches and production practices prove that NO of the hot blast stove x Mainly produced by high-temperature combustion, i.e. N in air 2 Oxidation to NO at high temperature x After the furnace dome temperature of the hot air is continuously increased to 1400 ℃, NO x The production amount is rapidly increased, so that the concentration of nitrogen oxides in the flue gas can not meet the requirement of environment protection and ultra-low emission, and the inter-crystal stress corrosion of the furnace shell in a high temperature area can be aggravated, thereby reducing the service life of the blast furnace hot blast stove. If the denitration equipment is matched with the hot blast stove independently, the investment and the management cost of the iron-making system can be greatly increased, and the investment and the management cost are not reimbursed.
Due to NO in the hot blast stove x The production of (2) is mainly dependent on 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, butThe vault temperature is reduced, the hot air temperature is reduced, and the operation of a blast furnace is seriously affected, so that the method for effectively reducing the generation and emission of nitrogen oxides of the hot blast furnace is imperative to be found.
CN201310067318.7 discloses a "self-circulation combustion method and system for flue gas of blast furnace hot blast stove", which mixes part of hot air introduced into blast furnace back with part of flue gas discharged outside as combustion-supporting gas of hot blast stove; because the oxygen content of the combustion-supporting gas is low, the returned hot air demand is large, and the stable operation of the blast furnace is seriously affected. CN202021283819.0 discloses a "flue gas recirculation combustion-supporting air system for direct-fired hot blast stove", which reduces the oxygen content of combustion-supporting air by increasing the flue gas regulating valve and the fresh air manual regulating structure to regulate the ratio of fresh air and flue gas, thereby reducing the combustion temperature and finally achieving the effect of reducing the emission of nitrogen oxides; although the method for reducing the emission of nitrogen oxides by using the content of combustion-supporting air is disclosed, specific technical measures and indexes of the implementation method are not described in detail, so that on one hand, the content of nitrogen oxides in flue gas can not be effectively reduced, on the other hand, the temperature of the hot blast furnace 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 accumulating type hot blast stove technical discussion', the conception of the flue gas circulation heat accumulating type hot blast stove technology is introduced, the flue gas emission of the hot blast stove is reduced through oxygen-enriched combustion and flue gas circulation, and the nitrogen oxide production is reduced through the reduction of the nitrogen proportion; however, the idea is only a theoretical stage, and as the oxygen enrichment amount increases, the vault temperature increases, which inevitably brings about rapid increase of the generation speed and the generation amount of nitrogen oxides, and as the emission amount of the flue gas decreases, the concentration of nitrogen oxides in the flue gas increases more greatly. Some of the above-described related patents and techniques can seriously affect the safe and stable operation of the blast furnace, and some lack of practical operability and practicality, and can not fundamentally solve the problem of exceeding the nitrogen oxide concentration of the hot blast stove.
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 the flue gas of a blast furnace hot blast stove. Solves the fundamental problem of the massive generation of nitrogen oxides, can greatly reduce the emission concentration of nitrogen oxides 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.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
the production method for reducing the emission concentration of nitrogen oxides in the flue gas of the blast furnace hot blast stove specifically comprises the following steps:
1) Introducing part of hot waste gas discharged to the atmosphere chimney into a pressure stabilizing mixer through an external smoke exhaust induced draft fan, introducing combustion air into the pressure stabilizing mixer through a combustion-supporting fan, mixing part of hot waste gas with the combustion 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 the mixed gas directly enters a hot blast stove, and the other part of the 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 booster sprayer; the gas of the gas pipeline is led into a gas preheater, heated by the gas preheater and then led into a combustion furnace; part of hot blast stove exhaust gas discharged from the hot blast stove is introduced into the combustion furnace through a high-temperature smoke induced draft fan;
4) In the combustion furnace, the other part of the fuel enters the combustion furnace to be combusted together with mixed gas, waste gas grease, hot gas and part of hot blast stove waste gas, and the fuel is the waste gas grease and the gas;
5) The flue gas after combustion in the combustion furnace respectively passes through the gas preheater and the air preheater, then enters a waste gas main pipeline and flows to an external smoke exhaust pipe;
6) 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 is introduced into the hot blast stove through a combustion starting position, and the other part is introduced into the hot blast stove at the upper part of the flame combustion direction; the gas in the gas pipeline enters the hot blast stove after being heated by the gas preheater, and is combusted with the mixed gas in the hot blast stove;
7) After the gas combusted in the hot blast furnace is subjected to blast heat exchange by the 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 atmosphere chimney from step 1) with combustion air, the volume of waste gas entering the external smoke exhaust induced draft fan accounts for 5% -25% of the final volume of the external discharged waste gas, the pressure of the external smoke exhaust induced draft fan is more than or equal to 7500pa, and the temperature of the circulated waste gas is 150-430 ℃.
Step 3) introducing hot blast stove waste gas 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 waste gas discharged from the hot blast stove.
And 4) respectively carrying out injection combustion on waste grease and coal gas in a combustion furnace, wherein the injection proportion of the waste grease after passing through a booster injector is 30-80% of the total injection fuel mass of the combustion furnace, the injection proportion of the coal gas is 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 waste gas of the combustion furnace is not lower than 200 ℃.
Step 5) preheating the coal gas and the combustion air through a coal gas preheater and an air preheater respectively, wherein the heat sources of the coal gas preheater and the air preheater are from the waste gas generated by the hot blast stove and the waste gas generated by the combustion furnace.
Step 6), the combustion starting part is introduced into 60-90% of the volume of the mixed gas entering the hot blast stove, and 10-40% of the volume of the mixed gas entering the hot blast stove is introduced into the upper part of the flame combustion direction.
Compared with the prior art, the method has the beneficial effects that:
the invention firstly introduces combustion-supporting air and coal gas into the hot blast stove from different combustion parts, changes the traditional combustion mode, increases the flame length in the hot blast stove on the premise of not reducing the temperature of the vault of the hot blast stove, reduces the temperature of the flame core, evenly distributes the flame temperature, improves the utilization efficiency of the coal gas, solves the problems of concentrated high temperature area and mass production of nitrogen oxides during combustion, and fundamentally reduces the production amount and emission concentration of the nitrogen oxides.
And secondly, by arranging the combustion furnace and spraying waste gas grease, the temperature of combustion-supporting air and gas is improved, the 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 multiple circulation of the flue gas in the hot blast stove and the combustion furnace, reasonable utilization of the heat of the flue gas is realized, and emission of nitrogen oxides is reduced.
The invention completely solves the problems of large emission of nitrogen oxides and exceeding emission concentration of the hot blast stove on the premise of not influencing the production of the blast furnace by the technology.
Drawings
FIG. 1 is a schematic diagram 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 external smoke exhaust induced draft fan; 5. a gas pipe; 6. a gas preheater; 7. an air preheater; 8. a blower; 9. a combustion furnace; 10. high-temperature flue gas induced draft fan; 11. a booster injector; 12. a waste grease pipe; 13. 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, with the benefit of this disclosure, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that variations and modifications can be made in the methods and applications described herein, and in the practice and application of the techniques of this invention, without departing from the spirit or scope of the invention.
The following detailed description of the invention further illustrates, but is not intended to limit, the scope of the invention.
As shown in fig. 1, a system for reducing the emission concentration of nitrogen oxides in flue gas of a blast furnace hot blast stove comprises a chimney 1, a combustion-supporting fan 2, a pressure stabilizing mixer 3, an external 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 booster injector 11, a waste grease pipeline 12, a hot blast stove 13 and a blast furnace 14.
The combustion-supporting fan 2 is connected with a pipeline of the pressure stabilizing mixer 3. The chimney 1, the external smoke exhaust induced draft fan 4 and the pressure stabilizing mixer 3 are connected in turn through pipelines. The pressure stabilizing mixer 3, the air preheater 7 and the combustion furnace 9 are connected in turn through pipelines.
The gas pipeline 5, the gas preheater 6, the hot blast stove 13 and the combustion furnace 9 are connected in turn through pipelines. The air blower 8, the hot blast stove 13 and the combustion furnace 9 are connected in sequence 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 injector 11 and the combustion furnace 9 are connected in turn in pipeline. The air preheater 7 is connected with a hot blast stove 13 pipeline, and the hot blast stove 13 is connected with a blast furnace 14 pipeline.
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 the blast furnace hot blast stove production system, part of hot waste gas discharged to the atmosphere chimney 1 is introduced into the pressure stabilizing mixer 3 through the outer exhaust gas induced draft fan 4, the volume of the waste gas entering the outer exhaust gas induced draft fan 4 accounts for 5-25% of the final volume of the outer exhaust gas, the pressure of the outer exhaust gas induced draft fan is more than or equal to 7500pa, and the temperature of the circulated waste gas is 150-430 ℃.
The combustion air is introduced into the pressure stabilizing mixer 3 through the combustion fan 2, part of hot waste gas is mixed with the combustion 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) After the mixed gas is preheated by the air preheater 7, a part of the mixed gas directly enters the hot blast stove 13. After the mixed gas is preheated by the air preheater 7, the other part of the mixed gas enters the combustion furnace 9.
3) The exhaust grease of the exhaust grease duct 12 is injected into the combustion furnace 9 through the booster injector 11. The gas of the gas pipeline 5 is led into the gas preheater 6, and is heated by the gas preheater 6 and then led into the combustion furnace 9. Part of the hot blast stove waste gas discharged from the hot blast stove 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 through the high-temperature flue gas induced draft fan 10 accounts for 3% -17% of the total volume of the waste gas discharged from 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 and the hot gas preheated by the gas preheater 6 are sprayed into the combustion furnace 9, and part of the hot blast furnace waste gas which is directly discharged from the hot blast stove 13 and not entering the gas preheater 6 is combusted together through the high-temperature flue gas induced draft fan 10. The fuel is waste gas grease and coal gas in the combustion process of the combustion furnace.
In the combustion furnace 9, the waste grease and the coal gas are respectively blown and combusted, the blowing proportion of the waste grease after passing through the booster injector 11 is 30-80% of the total blowing fuel mass of the combustion furnace, the blowing proportion of the coal gas is 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 more than or equal to 200 ℃.
5) The flue gas after combustion in the combustion furnace respectively passes through the gas preheater 6 and the air preheater 7, then enters the waste gas main pipeline and flows to the 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 the waste gas generated by the hot blast stove 13 and the waste gas generated by the 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 the gas mixture which directly enters the hot blast stove 13 with part of the step 2) is combusted according to a certain proportion. The mixed gas entering the hot blast stove 16 is divided into two parts, the combustion starting part is introduced into 60-90% of the volume of the mixed gas entering the hot blast stove 13, and 10-40% of the volume of the mixed gas entering the hot blast stove 13 is introduced into the upper part of the flame combustion direction.
7) After the gas combusted in the hot blast furnace 13 is subjected to blast heat exchange by the blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
[ example 1 ]
In the hot blast stove production system, hot waste gas with the temperature of 170 ℃ accounting for 6% of the volume of final waste gas discharged to an atmosphere chimney 1 is mixed with air from a combustion-supporting fan 2 in a pressure stabilizing mixer 3 through an external exhaust gas induced draft fan 4 with the induced draft 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 the mixed gas is preheated by the air preheater 7, a part of the mixed gas enters the combustion furnace 9, and is combusted together with waste grease 12 accounting for 32% of the total injection fuel mass of the combustion furnace 9 and hot gas accounting for 68% of the total injection mass of the combustion furnace 9 from the gas preheater 6 in an atomized state injected into the combustion furnace 9 by the booster injector 11, and hot blast furnace waste gas which is discharged from the hot blast furnace 13 and does not enter the gas preheater 6 yet and accounts for 6% of the total volume of waste gas discharged from the hot blast furnace by the high-temperature flue gas induced draft fan 10. The highest temperature of the combustion furnace 9 is 1048 ℃, the temperature of the combusted smoke is 260 ℃, and the part of smoke enters a waste gas main pipeline after passing through the gas preheater 6 and the air preheater 7 respectively and flows to the external smoke exhaust pipe 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 into the combustion starting part of the hot blast stove is 90% of the total mixed gas volume, and the volume of the mixed gas introduced into the upper part of the flame combustion direction is 10% of the total mixed gas volume. The gas directly introduced into the hot blast stove accounts for 80% of the total gas introduced into the hot blast stove at the combustion starting position, and the gas introduced into the upper part of the flame combustion direction accounts for 20% of the total gas introduced into the hot blast stove.
After the blast heat exchange of the blast furnace after combustion is carried out by the blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
Table 1 shows actual production data of inventive example 1 and comparative example 1
By comparison ofProduction data, when the vault temperature of the hot blast stove at 1280 ℃ is unchanged, the temperature of hot blast is increased by 5 ℃, and through the industrial application of the invention, the concentration of nitrogen oxides can be from 180mg/m 3 Down to 140mg/m 3 Meets the environmental protection emission requirement and ensures the stable and smooth operation of the blast furnace.
[ example 2 ]
In the hot blast stove production system, hot waste gas with the temperature of 200 ℃ accounting for 11 percent of the volume of final discharged waste gas discharged to an atmosphere chimney 1 is mixed with air from a combustion-supporting fan 2 in a pressure stabilizing mixer 3 through a draught fan 4 with the induced air 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 percent.
After being preheated by the air preheater 7, a part of the mixed gas enters the combustion furnace 9, and is combusted together with waste grease 12 accounting for 55% of the total injection fuel mass of the combustion furnace 9 and hot gas accounting for 45% of the total injection mass of the combustion furnace 9 from the gas preheater 6 in an atomized state sprayed into the combustion furnace by the booster sprayer 11, and hot blast furnace waste gas which is discharged from the hot blast stove 13 and is not yet enters the gas preheater 6 and accounts for 9% of the total volume of waste gas discharged from the hot blast stove by the high-temperature flue gas induced draft fan 10, wherein the highest temperature of the combustion furnace 9 is 1040 ℃, and the combusted flue gas temperature is 350 ℃, and the part of the flue gas enters a waste gas total pipeline after passing through the gas preheater 6 and the air preheater 7 respectively and flows to the external smoke discharging tube 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 into the combustion starting part of the hot blast stove accounts for 70% of the total mixed gas volume, and the volume of the mixed gas introduced into the upper part of the flame combustion direction accounts for 30% of the total mixed gas volume. The gas directly introduced into the hot blast stove accounts for 60% of the total gas introduced into the hot blast stove at the combustion starting position, and the gas introduced into the upper part of the flame combustion direction accounts for 40% of the total gas introduced into the hot blast stove.
After the blast heat exchange of the blast furnace after combustion is carried out by the blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
Table 2 shows actual production data of inventive example 2 and comparative example 2
By comparing production data, when the vault temperature of the hot blast stove at 1320 ℃ is unchanged, the temperature of the hot blast is increased by 2 ℃ and the concentration of nitrogen oxides can be increased from 260mg/m by the industrial application of the invention 3 Down to 180mg/m 3 Meets the environmental protection emission requirement and ensures the stable and smooth operation of the blast furnace.
[ example 3 ]
In the hot blast stove production system, hot waste gas which is discharged to the atmosphere chimney 1 and occupies 23 percent of the volume of the final discharged waste gas and has the temperature of 370 ℃ is mixed with air from a combustion-supporting fan 2 in a pressure stabilizing mixer 3 through a draught fan 4 with the induced air 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 percent.
After being preheated by the air preheater 7, a part of the mixed gas enters the combustion furnace 9, and is combusted together with waste grease 12 accounting for 75% of the total injection fuel mass of the combustion furnace 9 and hot gas accounting for 25% of the total injection mass of the combustion furnace 9 from the gas preheater 6 in an atomized state injected into the combustion furnace by the booster injector 11, and hot blast furnace waste gas which is not discharged from the hot blast stove 13 and accounts for 16% of the total volume of waste gas discharged from the hot blast stove and does not enter the gas preheater 6 through the high-temperature flue gas induced draft fan 10, wherein the highest temperature of the combustion furnace 9 is 1020 ℃, and the combusted flue gas temperature is 370 ℃, and the part of the flue gas enters a waste gas total pipeline after passing through the gas preheater 6 and the air preheater 7 respectively and flows to the external smoke discharging tube 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 into the combustion starting part of the hot blast stove accounts for 60% of the total mixed gas volume, and the volume of the mixed gas introduced into the upper part of the flame combustion direction accounts for 40% of the total mixed gas volume. The gas directly introduced into the hot blast stove accounts for 55% of the total gas introduced into the hot blast stove, and the gas introduced into the upper part of the flame combustion direction accounts for 45% of the total gas introduced into the hot blast stove.
After the blast heat exchange of the blast furnace after combustion is carried out by the blower 8, the generated high-temperature hot air is finally introduced into the blast furnace 14 for blast furnace production.
Table 3 shows actual production data of inventive example 3 and comparative example 3
By comparing production data, when the vault temperature of the hot blast stove at 1400 ℃ is unchanged, the temperature of the hot blast is increased by 10 ℃ and the concentration of nitrogen oxides can be increased from 310mg/m by the industrial application of the invention 3 Down to 185mg/m 3 Meets the environmental protection emission requirement and ensures the stable and smooth operation of the blast furnace.
The invention firstly introduces combustion-supporting air and coal gas into the hot blast stove 13 from different combustion parts, changes the traditional combustion mode, increases the flame length in the hot blast stove 13 on the premise of not reducing the vault temperature of the hot blast stove 13, reduces the temperature of the flame core, evenly distributes the flame temperature, improves the utilization efficiency of the coal gas, solves the problems of concentrated high temperature area and mass production of nitrogen oxides during combustion, and fundamentally reduces the production amount and emission concentration of the nitrogen oxides.
Secondly, by arranging the combustion furnace 9 and spraying waste gas grease, the temperature of combustion-supporting air and gas is improved, the 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, through the multiple circulation of the flue gas in the hot blast stove 13 and the combustion furnace 9, the reasonable utilization of the heat of the flue gas is realized, and the emission of nitrogen oxides is reduced.
The invention solves the fundamental problem of the massive generation of nitrogen oxides, can greatly reduce the emission concentration of nitrogen oxides 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 foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (7)
1. The production method for reducing the emission concentration of nitrogen oxides in the flue gas of the blast furnace hot blast stove is characterized by comprising the following steps of:
1) Introducing part of hot waste gas discharged to the atmosphere chimney into a pressure stabilizing mixer through an external smoke exhaust induced draft fan, introducing combustion air into the pressure stabilizing mixer through a combustion-supporting fan, mixing part of hot waste gas with the combustion 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 the mixed gas directly enters a hot blast stove, and the other part of the 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 booster sprayer; the gas of the gas pipeline is led into a gas preheater, heated by the gas preheater and then led into a combustion furnace; part of hot blast stove exhaust gas discharged from the hot blast stove is introduced into the combustion furnace through a high-temperature smoke induced draft fan;
4) In the combustion furnace, the other part of the fuel enters the combustion furnace to be combusted together with mixed gas, waste gas grease, hot gas and part of hot blast stove waste gas, and the fuel is the waste gas grease and the gas;
5) The flue gas after combustion in the combustion furnace respectively passes through the gas preheater and the air preheater, then enters a waste gas main pipeline and flows to an external smoke exhaust pipe;
6) 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 is introduced into the hot blast stove through a combustion starting position, and the other part is introduced into the hot blast stove at the upper part of the flame combustion direction; the gas in the gas pipeline enters the hot blast stove after being heated by the gas preheater, and is combusted with the mixed gas in the hot blast stove;
7) After the gas combusted in the hot blast furnace is subjected to blast heat exchange by the 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 mass percentage content of the mixed gas is 15.5% -20%.
3. 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 in the step 1), part of hot waste gas discharged to an atmosphere chimney is mixed with combustion air, the volume of waste gas entering an external flue gas induced draft fan accounts for 5% -25% of the final external flue gas volume, the pressure of the external flue gas induced draft fan is more than or equal to 7500pa, and the temperature of circulated waste gas is 150-430 ℃.
4. 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 3) is characterized in that the flue gas of the hot blast stove introduced into the combustion furnace through a high-temperature flue gas induced draft fan accounts for 3% -17% of the total volume of the flue gas discharged from the hot blast stove.
5. 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 in the step 4), the combustion of the waste gas grease and the gas is respectively carried out in a combustion furnace, the injection proportion of the waste gas grease after passing through a booster injector is 30% -80% of the total injection fuel mass of the combustion furnace, the injection proportion of the gas is 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 not lower than 200 ℃.
6. The method according to claim 1, wherein the step 5) of preheating the gas and the combustion air by a gas preheater and an air preheater, respectively, heat sources of the gas preheater and the air preheater are from exhaust gas generated by the hot blast stove and exhaust gas generated by the combustion stove.
7. 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 combustion starting part in the step 6) is introduced into the hot blast stove in an amount of 60% -90% by volume of the mixture, and the mixture introduced into the hot blast stove in the upper part of the flame combustion direction is introduced into the hot blast stove in an amount of 10% -40% by volume of the mixture.
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