CN114534450A - Process method and system for reducing carbon dioxide emission of iron smelting furnace - Google Patents

Process method and system for reducing carbon dioxide emission of iron smelting furnace Download PDF

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CN114534450A
CN114534450A CN202210060756.XA CN202210060756A CN114534450A CN 114534450 A CN114534450 A CN 114534450A CN 202210060756 A CN202210060756 A CN 202210060756A CN 114534450 A CN114534450 A CN 114534450A
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carbon dioxide
gas
liquid
smelting furnace
tower
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张华芹
鲁建国
李广敏
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Shanghai Rhyme New Energy Technology Co ltd
Zhenjiang Dongfang Electric Heating Technology Co ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456Removing acid components
    • B01D53/1475Removing carbon dioxide
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H3/00Air heaters
    • F24H3/02Air heaters with forced circulation
    • F24H3/04Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element
    • F24H3/0405Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27DDETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/008Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/10Reduction of greenhouse gas [GHG] emissions
    • Y02P10/122Reduction of greenhouse gas [GHG] emissions by capturing or storing CO2

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  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
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  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Manufacture Of Iron (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)

Abstract

The invention discloses a process method for reducing carbon dioxide emission of an iron smelting furnace, which comprises the following steps: introducing tail gas discharged by the smelting furnace into a washing tower, and absorbing carbon dioxide through organic liquid; heating the gas absorbed by the washing tower to be input into a smelting furnace as a reducing agent to participate in iron making; inputting the liquid which is discharged from the washing tower and absorbs the carbon dioxide into an analytic tower for analysis; and the desorption tower is used for desorbing to obtain liquid without carbon dioxide and carbon dioxide. The invention also discloses a system for reducing the emission of carbon dioxide from the iron smelting furnace. According to the process method and the system for reducing the carbon dioxide emission of the iron smelting furnace, coal gas is recycled, so that the emission of carbon dioxide is remarkably reduced, and the yield of iron is not influenced.

Description

Process method and system for reducing carbon dioxide emission of iron smelting furnace
Technical Field
The invention relates to the technical field of treatment of blast tail gas of smelting furnaces in the steel industry, in particular to a process method and a system for reducing carbon dioxide emission of an iron smelting furnace.
Background
In the formation of carbon emissions, the fireThe ratio of electricity, steel and metallurgy is close to 70%, the ratio of steel and metallurgy is about 30%, the ratio of steel and iron is 14%, and CO is2The global climate is warmed up due to a large amount of emission, the greenhouse effect is aggravated, the world countries frequently pay more and more attention to the emission control of carbon dioxide in extreme weather, the development of green and low carbon is the main melody of the development of the steel industry in the world, and therefore the significance of effectively controlling and reducing the emission of the carbon dioxide is great.
In the iron and steel industry, the iron-making link is a discharge of a large household, in the iron-making process of a traditional blast furnace, coke, sinter, pellets and the like generate a large amount of blast furnace gas in high-temperature smelting, the generated gas is led out from the top of the furnace and is used as fuel of a hot blast furnace, a heating furnace, a coke oven, a boiler and the like after dust removal, and is finally discharged in the form of carbon dioxide, the coke is directly used as a reducing agent or is converted into carbon monoxide to reduce iron in iron ore in the process, and the blast furnace gas Nm is produced per ton of iron according to the coke ratio of 400kg/t iron and the coal injection of 160kg/t iron3
The existing process method for reducing the emission of carbon dioxide of the iron smelting furnace influences the yield of molten iron while reducing the carbon dioxide, so that the production efficiency is low, and the actual production requirement cannot be met.
Disclosure of Invention
In view of the problems that the existing process method for reducing the carbon dioxide emission of the iron smelting furnace affects the yield of molten iron while reducing the carbon dioxide, has low production efficiency and can not meet the actual production requirement, the invention provides the process method, the system and the system for reducing the carbon dioxide emission of the iron smelting furnace, so that the emission of the carbon dioxide in the iron smelting process is reduced, and the yield of the molten iron is not reduced.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a reduce system that iron smelting furnace carbon dioxide discharged, includes smelting furnace, scrubbing tower, analytic tower, the smelting furnace includes gas outlet and wind gap, still includes the heater, the gas outlet of smelting furnace with the gas inlet of scrubbing tower is connected, scrubbing tower upper portion is equipped with liquid inlet, the gas outlet of scrubbing tower passes through the heater with the wind gap of smelting furnace is connected, the liquid outlet of scrubbing tower with the liquid inlet of analytic tower is connected, analytic tower is equipped with a gas outlet for discharge carbon dioxide.
A process for reducing carbon dioxide emissions from an iron smelting furnace comprising the steps of: introducing tail gas discharged by the smelting furnace into a washing tower, and absorbing carbon dioxide through organic liquid; heating the gas absorbed by the washing tower to be input into a smelting furnace as a reducing agent to participate in iron making; inputting the liquid which is discharged from the washing tower and absorbs the carbon dioxide into an analytical tower for analysis; and the desorption tower is used for desorbing to obtain liquid without carbon dioxide and carbon dioxide.
According to one aspect of the invention, the tail gas is subjected to dust removal and temperature reduction treatment before being introduced into the washing tower.
According to one aspect of the invention, the dust removal and temperature reduction treatment is followed by a pressurization and pressure stabilization treatment.
According to one aspect of the invention, the gas after absorbing carbon dioxide by the washing tower is subjected to purification treatment before being heated, and the purification treatment comprises gas-liquid separation by a first gas-liquid separation tank, so as to separate organic liquid entrained in the gas after absorbing carbon dioxide by the washing tower.
According to one aspect of the invention, the liquid discharged from the washing tower and absorbed with carbon dioxide is called rich liquid, the liquid without carbon dioxide is called lean liquid, the rich liquid is pressurized, filtered and subjected to heat exchange treatment before entering the desorption tower, the lean liquid flows out from a liquid outlet at the bottom of the desorption tower and enters an organic liquid storage tank after being subjected to heat exchange treatment, and the heat exchange treatment is carried out between the rich liquid and the lean liquid through a heat exchanger.
According to one aspect of the invention, the liquid in the organic liquid storage tank is pressurized and cooled and then is introduced into the liquid inlet of the washing tower to selectively absorb carbon dioxide in the coal gas.
According to one aspect of the invention, the carbon dioxide is output from the gas outlet of the desorption tower, cooled and subjected to gas-liquid separation in the second gas-liquid separation tank, the liquid phase flows back into the desorption tower, and the gas phase is discharged from the top of the second gas-liquid separation tank.
According to one aspect of the invention, the method comprises the step of heating the gas after the carbon dioxide is absorbed by the washing tower to a preset temperature through a first heater, and then introducing the gas into a gas inlet or a tuyere of the smelting furnace for reduction iron making.
According to one aspect of the invention, after the gas after the carbon dioxide is absorbed by the washing tower is heated by the first heater to a preset temperature, the gas enters the smelting furnace in two paths, one path is directly sent to the air inlet of the smelting furnace, and the other path is continuously heated by the second heater to a preset temperature and enters the tuyere of the smelting furnace.
The implementation of the invention has the advantages that: the tail gas of the smelting furnace is recycled, so that the indirect reduction area in the smelting furnace is enlarged, the development of indirect reduction is facilitated, the coke consumption per ton of iron can be improved, the emission of carbon dioxide is reduced, and the yield of molten iron is not reduced. Through purifying and heating the coal gas, the exothermic indirect reduction reaction in the smelting furnace is fully developed, the occurrence of the direct reduction reaction of the endothermic carbon and the iron oxide is reduced, the fuel consumption is reduced, and the aim of reducing the emission of carbon dioxide is fulfilled. The purpose of strengthening smelting can be achieved by returning coal gas to the tuyere to participate in the oxygen-enriched smelting step. Meanwhile, a carbon dioxide chemical absorption and desorption system is additionally arranged, so that carbon dioxide in the coal gas of the smelting furnace is captured and recycled, and the emission of carbon dioxide is further reduced. The process method can obtain great economic benefit and social environmental benefit, and plays a demonstration role in utilizing the coke oven gas of the iron and steel enterprises.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic flow diagram of a process and system for reducing carbon dioxide emissions from an iron smelting furnace according to the present invention.
1-smelting furnace; 2-a dust removal cooler; 3-a compressor; 4-a surge tank; 5-a washing tower; 6-a first gas-liquid separation tank; 7-a primary electric heater; 8-a secondary electric heater; 9-rich liquid delivery pump; 10-a filter; 11-lean-rich liquor heat exchanger; 12-a resolution column; 13-organic liquid storage tank; 14-a lean liquor delivery pump; 15-lean liquor cooler; 16-a purge gas cooler; 17-a second knock out pot; 18-reflux pump; 19-reboiler.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in FIG. 1, an iron smelting system that reduces carbon dioxide emission, includes smelting furnace 1, scrubbing tower 5, desorption tower 12, smelting furnace 1 includes gas outlet and wind gap, still includes first heater, smelting furnace 1 is equipped with an air inlet, smelting furnace 1's gas outlet with scrubbing tower 5's gas inlet is connected, scrubbing tower 5 upper portion is equipped with liquid inlet for let in the organic liquid of selectivity absorption carbon dioxide, scrubbing tower 5's gas outlet passes through first heater with the air inlet of smelting furnace 1 is connected, scrubbing tower 5's liquid outlet with the liquid inlet of desorption tower 12 is connected, desorption tower 12 is equipped with a gas outlet for discharge carbon dioxide.
In practical application, a reduce iron smelting system that carbon dioxide discharged still includes dust removal heat sink 2, the access connection of dust removal heat sink 2 the gas outlet of smelting furnace 1, the exit linkage of dust removal heat sink 2 the gas inlet of scrubbing tower 5. Further, a compressor 3 and a surge tank 4 can be added, the outlet of the dust removal cooler 2 is connected with the inlet of the compressor 3, the outlet of the compressor 3 is connected with the inlet of the surge tank 4, and the outlet of the surge tank 4 is connected with the gas inlet of the washing tower 5. Further, the gas-liquid separation device further comprises a first gas-liquid separation tank 6, a gas outlet at the top of the washing tower 5 is connected with an inlet of the first gas-liquid separation tank 6, and a gas phase outlet of the first gas-liquid separation tank 6 is connected with the first heater. The first heater may be a primary electric heater 7. The first gas-liquid separation tank 6 is used for separating organic liquid carried in gas from a gas outlet of the washing tower 5.
In practical application, the desorption tower 12 includes an upper liquid inlet, a bottom liquid outlet, and a top gas phase outlet, the liquid outlet at the lower part of the washing tower 5 is connected to the top liquid inlet of the desorption tower 12 through a rich liquid delivery pump 9, a filter 10, and a heat exchanger 11, the top gas phase outlet is connected to a purge gas cooler 16 and a second gas-liquid separation tank 17, the top gas phase outlet of the desorption tower 12 is connected to an inlet of the purge gas cooler 16, an outlet of the purge gas cooler 16 is connected to a gas inlet of the second gas-liquid separation tank 17, and a gas phase outlet is disposed at the top of the second gas-liquid separation tank 17 and used for discharging carbon dioxide. In practical application, the gas phase outlet can be connected with a pipeline, and the pipeline can be connected with a hot blast stove. A liquid phase outlet is arranged at the bottom of the second gas-liquid separation tank 17, the liquid phase outlet is connected with an inlet of a reflux pump 18, and an outlet of the reflux pump 18 is connected with a liquid inlet of the desorption tower 12. A reboiler 19 is connected to the outside of the desorption tower 12 for continuously supplying the vapor at the bottom of the desorption tower 12.
Specifically, the outlet of the filter 10 is connected to the cold material flow inlet of the heat exchanger 11, and the cold material flow outlet of the heat exchanger 11 is connected to the liquid inlet at the upper part of the desorption tower 12. The liquid outlet of the desorption tower 12 is connected with the hot material flow inlet of the heat exchanger 11, and the hot material flow outlet of the heat exchanger 11 is connected with the organic liquid storage tank 13. And a liquid outlet at the bottom of the desorption tower 12 is connected with an inlet of the organic liquid storage tank 13. The liquid outlet of the organic liquid storage tank 13 is connected with the upper liquid phase inlet of the washing tower 5 through a barren liquor delivery pump 14 and a barren liquor cooler 15.
In the invention, a second heater can be added, the rear part of the first heater is divided into two paths, one path is connected with the air inlet of the smelting furnace 1, and the other path is connected with the air inlet of the smelting furnace 1 through the second heater. Specifically, the second heater is a secondary electric heater 8, and heats the gas to a higher preset temperature to strengthen smelting.
The invention also comprises a process method for reducing the emission of carbon dioxide from the iron smelting furnace, which comprises the following steps: introducing tail gas discharged by the smelting furnace 1 into a washing tower 5, and absorbing carbon dioxide through organic liquid; heating the gas absorbed by the washing tower 5 and inputting the heated gas into the smelting furnace 1 to be used as a reducing agent to participate in iron making; the liquid which is discharged from the washing tower 5 and absorbs the carbon dioxide is input into an analysis tower 12 for analysis; the desorption tower 12 desorbs to obtain carbon dioxide-removed liquid and carbon dioxide.
In actual production, the iron-making process is to add raw materials of iron ore, coke and pellets into the smelting furnace 1 in a certain proportion layer by layer, and a large amount of oxygen-enriched air heated by the hot blast stove is blown into the smelting furnace 1 from an air port of the smelting furnace 1, so that the coke is combusted to generate carbon dioxide, the carbon dioxide reacts with the hot coke on the upper layer to be reduced into carbon monoxide, and the carbon monoxide reacts with the continuously descending iron ore. Wherein the iron oxide is gradually reduced into liquid iron, commonly known as molten iron. After the reduced liquid iron is accumulated to a certain degree, the liquid iron is discharged from the bottom of the smelting furnace 1 and is loaded into a hot metal ladle to be sent to a steel plant. The ironmaking process simultaneously produces two byproducts, namely coal gas and slag. The slag is produced by combining non-reducible impurities in the ore with fluxes such as limestone and the like, is discharged from a slag hole, and is completely used as a cement production raw material after water quenching treatment. The generated coal gas is led out from the air outlet at the top of the smelting furnace 1. In the iron-making process, the coke, the combustion of injected fuel and the externally introduced hot air provide all heat required by blast furnace smelting, wherein the heat supply ratio of the coke combustion is up to 75-80%. Because the coke has good air permeability, the raw materials can be fully reduced along with the rising of the coal gas and the falling of the furnace burden.
In practical application, the coal gas which is discharged from the smelting furnace 1 enters the washing tower 5, enters the washing tower 5 from a gas inlet at the bottom of the washing tower 5, and is in countercurrent contact with organic liquid in the washing tower 5, wherein the organic liquid is used for selectively absorbing carbon dioxide in the coal gas, the organic liquid after absorbing the carbon dioxide is called rich liquid, so that the coal gas only contains gases such as methane, hydrogen, carbon monoxide and the like, the coal gas is heated to a preset temperature after coming out of the top of the washing tower 5, the heated coal gas has a certain temperature, and the coal gas is introduced into the smelting furnace 1 to participate in chemical reaction as a reducing agent.
The invention relates to a process method for reducing carbon dioxide emission of an iron smelting furnace, which comprises the steps of capturing and absorbing carbon dioxide in generated coal gas by a washing tower 5, heating the coal gas without the carbon dioxide to form coal gas with a certain temperature, wherein the main components of the coal gas are reducing gases such as carbon monoxide and hydrogen, the consumption of combustion-supporting air or oxygen enrichment can be effectively reduced due to the heat brought by heating, and the coal gas contains a large amount of reducing gases such as hydrogen, is a high-quality reducing agent, has the advantages of high reducing speed, low heat consumption and the like, and is beneficial to improving the production efficiency of the smelting furnace 1.
The coal gas discharged from the smelting furnace 1 is subjected to a series of treatments and then returned to the smelting furnace 1 for iron making, so that part of coke can be replaced to play a role of a reducing agent, the using amount of the coke for iron making can be reduced, the fuel ratio and the pig iron cost are reduced, the generation of carbon dioxide in the iron making process is reduced, the emission of the carbon dioxide is reduced, and the emission of the carbon dioxide is remarkably reduced. And meanwhile, the yield of the molten iron is not influenced.
In the invention, before the tail gas is introduced into the washing tower 5, the tail gas is subjected to dust removal and temperature reduction treatment and pressurization and pressure stabilization treatment. In addition, the gas after the carbon dioxide is absorbed by the washing tower 5 is purified before being heated, wherein the purification treatment comprises gas-liquid separation by a first gas-liquid separation tank 6, and is used for separating organic liquid carried in the gas after the carbon dioxide is absorbed by the washing tower 5 to obtain purified gas.
As a preferable scheme of the invention, the method comprises the steps of heating the gas after the carbon dioxide is absorbed by the washing tower 5 to a preset temperature through first heating equipment, and then introducing the gas into a gas inlet of a furnace body of the smelting furnace 1 or a tuyere at the lower part of the smelting furnace 1 for reduction iron making. Further, the predetermined temperature at the time of passing into the tuyere is higher than the predetermined temperature at the time of passing into the air inlet.
Preferably, heat through first firing equipment behind the gas after scrubbing tower 5 absorbs the carbon dioxide, gas divides two to advance smelting furnace 1, one is directly gone the air inlet of smelting furnace 1, another strand is continued to be heated to preset temperature by second firing equipment and is got into the wind gap of smelting furnace 1 participates in wind gap oxygen boosting and smelts the step, reaches the purpose of intensive smelting. The process allows the indirect reduction zone in the smelting furnace 1 to be enlarged.
In the present invention, the carbon dioxide-absorbed liquid discharged from the scrubber 5 is referred to as a rich liquid, and the carbon dioxide-removed liquid is referred to as a lean liquid. The rich solution is pressurized, filtered and subjected to heat exchange treatment before entering the desorption tower 12, the lean solution flows out from a liquid outlet at the bottom of the desorption tower 12 and enters an organic solution storage tank 13 after being subjected to heat exchange treatment, and the heat exchange treatment is carried out between the rich solution and the lean solution through a heat exchanger. Specifically, the organic liquid after absorbing carbon dioxide is discharged from a liquid outlet at the bottom of the washing tower 5, subjected to pressurization, filtration and heat exchange treatment, and then sent to a liquid inlet at the top of the desorption tower 12 to be in countercurrent contact with ascending vapor at the bottom of the desorption tower 12, so that carbon dioxide in the organic liquid is heated and separated out, and the carbon dioxide is discharged from a gas phase outlet at the top of the desorption tower 12.
Further, after being output from the gas outlet at the top of the desorption tower 12, the carbon dioxide can be cooled, and then is subjected to gas-liquid separation by the second gas-liquid separation tank 17, and the entrained organic liquid is separated into liquid phase and flows back to the desorption tower 12 to be recycled as carbon dioxide absorption liquid. The carbon dioxide gas phase is discharged from the top of the second gas-liquid separation tank 17, and may be incorporated into a carbon dioxide line. And the liquid output from the liquid outlet at the bottom of the desorption tower 12 enters an organic liquid storage tank 13 after being subjected to heat exchange by the lean-rich liquid heat exchanger 11 for recycling. The heat exchange treatment is carried out between the rich solution and the lean solution through a heat exchanger. And the liquid in the organic liquid storage tank 13 is pressurized and cooled and then is introduced into the liquid inlet of the washing tower 5 to be used for selectively absorbing carbon dioxide in the coal gas.
In practical application, the organic liquid for absorbing carbon dioxide may be specifically an alkaline absorbent solution, the alkaline absorbent solution reacts with carbon dioxide in coal gas and undergoes a chemical reaction to form unstable salts, and the unstable salts can be reversely decomposed under certain conditions to release carbon dioxide, so as to achieve separation and recovery of carbon dioxide from blast furnace gas. By additionally arranging the carbon dioxide chemical absorption and analysis system, the carbon dioxide in the coal gas is captured and recycled.
Further, the separated carbon dioxide can be matched with the waste gas of various industrial furnaces for recycling treatment: for example, the obtained carbon dioxide is compressed and then enters a hot blast stove of an air supply system of the smelting furnace 1 through a gas switching valve to be used as carrier gas of an injection fuel system of the smelting furnace 1 for iron making of the smelting furnace 1, so that the cyclic utilization in a gas workshop of the smelting furnace 1 is realized; or can replace partial air to enter the hot blast stove for preheating and then be used for the blast of the smelting furnace 1 to participate in the iron making of the smelting furnace 1, and carbon dioxide reacts with carbon in the smelting furnace 1 to generate carbon monoxide for promoting the indirect reduction in the smelting furnace 1. The coal gas of the smelting furnace 1 is recycled in the workshop of the smelting furnace 1, the emission of greenhouse gas can be effectively reduced, and the environmental pressure is relieved.
The first embodiment is as follows: process method for reducing carbon dioxide emission of iron smelting furnace
In the iron smelting process, coal gas which is discharged from a smelting furnace 1 is dedusted and cooled by a dedusting cooler 2, pressurized by a compressor 3 and stabilized by a pressure stabilizing tank 4, and then enters a washing tower 5 with organic liquid, wherein the coal gas flows from bottom to top in the washing tower 5, the washing tower 5 is in countercurrent contact with the organic liquid which enters the washing tower 5 from the upper part of the washing tower and can absorb carbon dioxide, the organic liquid selectively absorbs the carbon dioxide in the coal gas, and the organic liquid after absorbing the carbon dioxide is called rich liquid. The organic liquid selectively absorbs the carbon dioxide in the coal gas, so that the coal gas only contains gases such as methane, hydrogen, carbon monoxide and the like. The coal gas is discharged from the top of the washing tower 5, and then the organic liquid carried by the coal gas is settled and separated by the first gas-liquid separation tank 6, the coal gas is heated by the primary electric heater 7, and the heated coal gas is directly sent to the gas inlet of the furnace body of the smelting furnace 1. The coal gas absorbing carbon dioxide is heated and then returned to the smelting furnace 1 for iron making, and can replace part of coke to play the role of a reducing agent. Meanwhile, after the rich solution comes out from the bottom of the washing tower 5, the rich solution is input into a filter 10 through a rich solution delivery pump 9 for filtering, then is subjected to heat exchange treatment through a lean rich solution heat exchanger 11, and is sent to the top of the desorption tower 12 to be in countercurrent contact with ascending steam at the bottom of the desorption tower 12, and the steam is heated through a reboiler 19 after being subjected to heat exchange condensation to be recycled, so that the steam consumption is effectively reduced. Carbon dioxide in the organic liquid is heated and precipitated, and is discharged out of the system from the top of the desorption tower 12, cooled by the purge gas cooler 16, cooled, and then flows through the second gas-liquid separation tank 17, the liquid phase flows back into the desorption tower 12 through the reflux pump 18, and the carbon dioxide gas phase is discharged from the top of the gas-liquid separation tank 17. The organic liquid after the carbon dioxide is resolved is called a lean liquid, and the lean liquid flows out from the bottom of the resolving tower 12, enters an organic liquid storage tank 13 through a lean rich liquid heat exchanger 11, is sent to the washing tower 5 through a lean liquid conveying pump 14 to be repeatedly used, and is recycled as a carbon dioxide absorption liquid.
This embodiment a technological method for reducing iron smelting furnace carbon dioxide emission, directly return after the coal gas heating after will heating 1 shaft of smelting furnace participates in the reaction, because through the heating, bring the heat into, can effectively reduce combustion air or the quantity of oxygen boosting, secondly, this technology can make the interior indirect reduction zone of smelting furnace enlarge, is favorable to the development of indirect reduction, is favorable to improving smelting furnace production efficiency to can make ton iron coke consumption improve, and then reduce the emission of carbon dioxide, when reducing the emission of iron-making in-process carbon dioxide and not reduce the output of molten iron.
The process method is additionally provided with the washing tower 5 and the desorption tower 12, and the carbon dioxide in the coal gas is captured, recycled and utilized through the chemical absorption and desorption system, so that the emission of the carbon dioxide is further reduced. The design of the lean-rich liquid heat exchanger 11 and the reboiler 19 can reduce energy consumption and save economy.
Example two: process method for reducing carbon dioxide emission of iron smelting furnace
In the iron smelting process, coal gas which is discharged from a smelting furnace 1 is dedusted and cooled by a dedusting cooler 2, pressurized by a compressor 3 and stabilized by a pressure stabilizing tank 4, and then enters a washing tower 5 with organic liquid, wherein the coal gas flows from bottom to top in the washing tower 5, the washing tower 5 is in countercurrent contact with the organic liquid which enters the washing tower 5 from the upper part of the washing tower and can absorb carbon dioxide, the organic liquid selectively absorbs the carbon dioxide in the coal gas, and the organic liquid after absorbing the carbon dioxide is called rich liquid. The organic liquid selectively absorbs the carbon dioxide in the coal gas, so that the coal gas only contains gases such as methane, hydrogen, carbon monoxide and the like. This coal gas is followed washing tower 5 top and is come out back through first gas-liquid knockout drum 6 with the organic liquid sedimentation separation back of smuggleing secretly, and this coal gas is heated by one-level electric heater 7, and the coal gas after the heating can be divided two and gets into smelting furnace 1, and one directly goes the shaft of a furnace, and another strand is heated to higher temperature by second grade electric heater 8 and is got into the wind gap of smelting furnace 1 returns smelting furnace 1 through the coal gas that will absorb carbon dioxide and is used for the iron-making, can replace partial coke to play the effect of reductant. Meanwhile, after the rich solution comes out from the bottom of the washing tower 5, the rich solution is input into a filter 10 through a rich solution delivery pump 9 for filtering, then is subjected to heat exchange treatment through a lean rich solution heat exchanger 11, and is sent to the top of the desorption tower 12 to be in countercurrent contact with ascending steam at the bottom of the desorption tower 12, and the steam is heated through a reboiler 19 after being subjected to heat exchange condensation to be recycled, so that the steam consumption is effectively reduced. Carbon dioxide in the organic liquid is heated and precipitated, and is discharged out of the system from the top of the desorption tower 12, cooled by the purge gas cooler 16, cooled, and then flows through the second gas-liquid separation tank 17, the liquid phase flows back into the desorption tower 12 through the reflux pump 18, and the carbon dioxide gas phase is discharged from the top of the gas-liquid separation tank 17. The organic liquid after the carbon dioxide is resolved is called a lean liquid, and the lean liquid flows out from the bottom of the resolving tower 12, enters an organic liquid storage tank 13 through a lean rich liquid heat exchanger 11, is sent to the washing tower 5 through a lean liquid conveying pump 14 to be repeatedly used, and is recycled as a carbon dioxide absorption liquid.
The process method for reducing carbon dioxide emission of the iron smelting furnace has the advantages that heated coal gas is divided into two streams to enter the smelting furnace 1, one stream directly goes to a furnace body, the other stream is continuously heated to a higher temperature by the second-level electric heater 8 to enter the tuyere of the smelting furnace 1, the indirect reduction area in the smelting furnace 1 can be enlarged by the process, development of indirect reduction is facilitated, accordingly, the iron coke consumption per ton can be improved, and emission of carbon dioxide is reduced.
Because the smelting furnace 1 fully develops exothermic indirect reduction reaction, the occurrence of endothermic direct reduction reaction of carbon and iron oxide is reduced, the fuel consumption is reduced, the purpose of reducing carbon dioxide emission is achieved, and the purpose of strengthening smelting is achieved by increasing tuyere oxygen-enriched smelting. The discharge of carbon dioxide in the ironmaking process is reduced, and meanwhile, the yield of molten iron is not reduced. The problems of energy waste and environmental pollution caused by the empty burning of the coke oven gas are avoided, great economic benefits and social environmental benefits are obtained, and a demonstration effect is played for the utilization of the coke oven gas of the iron and steel enterprises.
The process method is additionally provided with the washing tower 5 and the desorption tower 12, and the carbon dioxide in the blast furnace gas is captured, recycled and utilized through the chemical absorption and desorption system, so that the emission of the carbon dioxide is further reduced. The design of the lean-rich liquid heat exchanger 11 and the reboiler 19 can reduce energy consumption and save economy.
The implementation of the invention has the advantages that: a process method and a system for reducing the emission of carbon dioxide of an iron smelting furnace can enlarge an indirect reduction area in the smelting furnace by recycling the tail gas of the smelting furnace, and is beneficial to the development of indirect reduction, thereby improving the coke consumption per ton of iron, further reducing the emission of carbon dioxide, and simultaneously not reducing the yield of molten iron. Through purifying and heating the coal gas, the exothermic indirect reduction reaction in the smelting furnace is fully developed, the occurrence of the direct reduction reaction of the endothermic carbon and the iron oxide is reduced, the fuel consumption is reduced, and the aim of reducing the emission of carbon dioxide is fulfilled. The purpose of strengthening smelting can be achieved by returning coal gas to the tuyere to participate in the oxygen-enriched smelting step. Meanwhile, a carbon dioxide chemical absorption and desorption system is additionally arranged, so that carbon dioxide in the coal gas of the smelting furnace is captured and recycled, and the emission of carbon dioxide is further reduced. The process method can obtain great economic benefit and social environmental benefit, and plays a demonstration role in utilizing the coke oven gas of the iron and steel enterprises.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (10)

1. The utility model provides a reduce system that iron smelting furnace carbon dioxide discharged, includes smelting furnace, scrubbing tower, analytic tower, the smelting furnace includes gas outlet and wind gap, its characterized in that still includes the heater, the gas outlet of smelting furnace with the gas access connection of scrubbing tower, scrubbing tower upper portion is equipped with liquid inlet, the gas outlet of scrubbing tower passes through the heater with the wind gap of smelting furnace is connected, the liquid outlet of scrubbing tower with the liquid access connection of analytic tower, analytic tower is equipped with a gas outlet for discharge carbon dioxide.
2. A process for reducing carbon dioxide emissions from an iron smelting furnace, comprising the steps of:
introducing tail gas discharged by the smelting furnace into a washing tower, and absorbing carbon dioxide by using organic liquid;
heating the gas absorbed by the washing tower to be input into a smelting furnace as a reducing agent to participate in iron making;
inputting the liquid which is discharged from the washing tower and absorbs the carbon dioxide into an analytical tower for analysis;
and the desorption tower is used for desorbing to obtain liquid without carbon dioxide and carbon dioxide.
3. The process of claim 2, wherein the off-gas is dedusted and cooled before being introduced into the scrubber.
4. The process of reducing carbon dioxide emissions from an iron smelting furnace according to claim 3, wherein the dedusting and cooling process is followed by a pressure stabilization process.
5. The process according to claim 2, wherein the gas after absorption of carbon dioxide by the scrubber is subjected to a purification treatment before heating, the purification treatment comprising a gas-liquid separation in a first gas-liquid separation tank for separating organic liquid entrained in the gas after absorption of carbon dioxide by the scrubber.
6. The process of claim 2, wherein the liquid discharged from the washing tower and absorbing carbon dioxide is called rich liquid, the liquid without carbon dioxide is called lean liquid, the rich liquid is pressurized, filtered and subjected to heat exchange before entering the desorption tower, the lean liquid flows out from a liquid outlet at the bottom of the desorption tower and enters an organic liquid storage tank after being subjected to heat exchange treatment, and the heat exchange treatment is performed between the rich liquid and the lean liquid through a heat exchanger.
7. The process according to claim 6, wherein the liquid in the organic liquid storage tank is pressurized and cooled before being introduced into the liquid inlet of the scrubber for selective absorption of carbon dioxide from the gas.
8. The process according to claim 2, wherein the carbon dioxide is discharged from the outlet of the desorption tower, cooled and then subjected to gas-liquid separation in the second gas-liquid separation tank, the liquid phase is returned to the desorption tower, and the gas phase is discharged from the top of the second gas-liquid separation tank.
9. The process according to any one of claims 2 to 8, wherein the gas after absorption of carbon dioxide in the scrubbing tower is heated by the first heater to a predetermined temperature and then passed to the inlet or tuyere of the smelting furnace for reduction to produce iron.
10. The process of claim 9, wherein the gas after carbon dioxide absorption in the scrubber is heated by the first heater to a predetermined temperature, and then enters the smelting furnace in two streams, one stream is directed to the gas inlet of the smelting furnace, and the other stream is further heated by the second heater to a predetermined temperature and enters the tuyere of the smelting furnace.
CN202210060756.XA 2022-01-19 2022-01-19 Process method and system for reducing carbon dioxide emission of iron smelting furnace Pending CN114534450A (en)

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WO2019150204A1 (en) * 2018-02-01 2019-08-08 МОШКОВ, Владимир Nitrogen-free pig iron smelting technology with oxygen and carbon dioxide blown into a blast furnace
CN112126477A (en) * 2020-09-17 2020-12-25 安徽工业大学 Carbon dioxide capture system and method based on blast furnace slag washing water waste heat recycling
CN113336193A (en) * 2021-06-24 2021-09-03 中石化南京化工研究院有限公司 Decarburization device and method for preparing reducing gas from oxygen blast furnace gas

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101314102A (en) * 2008-05-30 2008-12-03 西安热工研究院有限公司 Method and apparatus for collecting carbonic anhydride in coal-fired plant flue gas
CN103966383A (en) * 2014-04-15 2014-08-06 山西太钢不锈钢股份有限公司 Melting method of oxygen-enriched shaft furnace
WO2019150204A1 (en) * 2018-02-01 2019-08-08 МОШКОВ, Владимир Nitrogen-free pig iron smelting technology with oxygen and carbon dioxide blown into a blast furnace
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