CN114807473B - Low-carbon total-oxygen blast furnace ironmaking process - Google Patents
Low-carbon total-oxygen blast furnace ironmaking process Download PDFInfo
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- CN114807473B CN114807473B CN202210497099.5A CN202210497099A CN114807473B CN 114807473 B CN114807473 B CN 114807473B CN 202210497099 A CN202210497099 A CN 202210497099A CN 114807473 B CN114807473 B CN 114807473B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/06—Making pig-iron in the blast furnace using top gas in the blast furnace process
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/001—Injecting additional fuel or reducing agents
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/001—Injecting additional fuel or reducing agents
- C21B2005/005—Selection or treatment of the reducing gases
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- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/10—Reduction of greenhouse gas [GHG] emissions
- Y02P10/122—Reduction of greenhouse gas [GHG] emissions by capturing or storing CO2
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Abstract
The invention relates to a low-carbon total-oxygen blast furnace ironmaking process, and belongs to the field of ferrous metallurgy. By O 2 /CO 2 The circulating flue gas is used as combustion improver to be mixed with top furnace gas instead of air and then is subjected to oxygen-enriched combustion, and flue gas CO generated by the oxygen-enriched combustion is generated 2 High concentration, convenient for CO 2 Collecting, sealing or recycling; the heat of the high-temperature flue gas is used for preheating oxygen and circulating top gas, so that the process performance of the blast furnace and the quality of the top gas can be improved, and the energy consumption can be reduced.
Description
Technical Field
The invention relates to a low-carbon total-oxygen blast furnace ironmaking process, and belongs to the field of ferrous metallurgy.
Background
The iron and steel industry is the prop industry of national economy in China and is also CO 2 The non-electric power industry with highest emission occupies CO in China 2 And the total discharge amount is more than 16 percent. In long-run steel production, about 70% of CO 2 The emissions are concentrated in the ironmaking process. Therefore, the core of carbon emission reduction in the iron and steel industry is to reduce the carbon emission of the ironmaking process, i.e. the carbon emission of the blast furnace.
The top furnace gas circulation-oxygen blast furnace ironmaking technology is one of the low carbon ironmaking technologies with the most development prospect, mainly uses air with the oxygen volume fraction of more than 21% to support combustion, increases the combustion intensity of coal dust in the blast furnace by increasing the oxygen concentration, enhances the reduction activity to reduce the consumption of coke, and reduces the carbon emission. Along with the increase of the oxygen enrichment rate, the coke ratio and the carbon consumption of the whole process are reduced, and the energy saving and emission reduction effect is optimal under the total oxygen atmosphere. Compared with the traditional blast furnace, the top furnace gas generated by the total oxygen blast furnace contains almost no N 2 And the CO content is greatly improved, so that the gas quality is improved.
However, the total oxygen blast furnace has several problems as follows:
1. CO in the produced top gas 2 The content reaches 35 to 40 percent, and CO is directly removed from the top furnace gas 2 Still the difficulty and cost of (a)Higher, there is still a great carbon capture potential.
2. Preheating the circulating top gas and pure oxygen blown into the blast furnace requires the consumption of a large amount of heat while producing a large amount of CO 2 And (5) discharging.
Oxygen-enriched combustion of CO 2 Flue gas circulation technology as a technology capable of reducing CO in large scale 2 Mainstream carbon capture technology of emissions, and isolation of N 2 The total-oxygen blast furnace ironmaking process has good acceptance and coupling performance, and is hopeful to greatly reduce CO in the total-oxygen blast furnace ironmaking process flow 2 Is difficult and costly to capture.
Disclosure of Invention
Aiming at the technical problems, the invention aims to provide a low-carbon total-oxygen blast furnace ironmaking process. By O 2 /CO 2 The circulating flue gas is used as combustion improver to be mixed with top furnace gas instead of air and then is subjected to oxygen-enriched combustion, and flue gas CO generated by the oxygen-enriched combustion is generated 2 High concentration, convenient for CO 2 Collecting, sealing or recycling; the heat of the high-temperature flue gas is used for preheating oxygen and circulating top gas, so that the process performance of the blast furnace and the quality of the top gas can be improved, and the energy consumption can be reduced.
The invention provides a low-carbon total-oxygen blast furnace ironmaking process which comprises a blast furnace body, an oxygen-enriched combustion device, a primary heat exchange device, a secondary heat exchange device, a tertiary heat exchange device, a pressure swing adsorption device, an air separation device, a cooling dehydration device, a compression condensing device and a carbon dioxide storage device;
the process comprises the following steps:
the air enters the air separation device to be separated, and the produced pure oxygen is separated into first pure oxygen and second pure oxygen;
the top gas led out from the blast furnace body is divided into a first top gas, a second top gas and a third top gas;
the first furnace top gas is sent into the oxygen-enriched combustion device for combustion, and the generated high-temperature flue gas is divided into first high-temperature flue gas and second high-temperature flue gas;
the first high-temperature flue gas is blown into a blast furnace from the furnace belly part of the blast furnace body and is used for preheating materials;
the second high-temperature flue gas sequentially flows through the primary heat exchange device, the secondary heat exchange device and the tertiary heat exchange device and is used for preheating the second top gas and the first pure oxygen;
after the first pure oxygen is preheated, blowing the first pure oxygen into a blast furnace from a hearth tuyere of the blast furnace body;
the second top gas is firstly sent into the pressure swing adsorption device to remove CO 2 Then sequentially flowing through the secondary heat exchange device and the primary heat exchange device for preheating, and finally blowing the air into the blast furnace from a hearth tuyere of the blast furnace body;
the third top gas is externally supplied;
the low-temperature flue gas from the three-stage heat exchange device is sent to the cooling and dehydrating device for dehydration, and the dehydrated low-temperature flue gas is divided into a first low-temperature flue gas and a second low-temperature flue gas;
the first low-temperature flue gas is sent to the compression condensing device, compressed and condensed into liquid state and then stored in the carbon dioxide storage device;
the second low-temperature flue gas is mixed with the second pure oxygen to form O 2 /CO 2 And (3) circulating flue gas, and sending the circulating flue gas into the oxygen-enriched combustion device to be mixed and combusted with the first furnace top gas.
Further, the oxygen purity of the first pure oxygen and the second pure oxygen is not less than 95%.
Further, in the top gas led out from the blast furnace body, the volume ratio of the first top gas is 20% -30%, the volume ratio of the second top gas is 60% -90%, and the balance is the third top gas.
Further, the O 2 /CO 2 In the circulating flue gas, the volume ratio of the second low-temperature flue gas is 70% -75%, and the volume ratio of the second pure oxygen is 25% -30%.
Further, in the high-temperature flue gas generated by the oxygen-enriched combustion device, the volume ratio of the first high-temperature flue gas is 5-10%, and the balance is the second high-temperature flue gas.
Further, low-temperature flue gas CO coming out of the three-stage heat exchange device 2 The concentration is not lower than 90%, and the temperature is 160-220 ℃.
Further, the temperature of the first pure oxygen and the second top gas is 1200-1300 ℃ when the first pure oxygen and the second top gas are blown into the blast furnace from the hearth tuyere of the blast furnace body.
Further, when the volume ratio of the second top gas is high to a certain value, the heat generated by the combustion of the first top gas in the oxygen-enriched combustion device is insufficient to preheat the first pure oxygen and the second top gas to 1200-1300 ℃, and the external supplementary gas can enter the oxygen-enriched combustion device to burn to supplement heat.
Compared with the prior art, the invention has the following advantages:
1. at the same time of providing heat by oxygen-enriched combustion of part of top gas, CO with volume concentration of up to 85% can be realized in a flue gas circulation mode 2 The flue gas can realize CO at a low cost 2 Is captured, stored and utilized. Compared with the traditional blast furnace, the carbon emission can be reduced by more than 80 percent.
2. Top gas at O 2 /CO 2 The oxygen-enriched combustion is carried out in the circulating flue gas atmosphere, so that the fuel combustion and flue gas heat exchange characteristics can be obviously improved, and the temperature of the outlet flue gas is increased, so that the temperature of circulating top gas and oxygen can be increased.
3. The system exchanges heat through the multi-stage heat exchanger, the temperature of the low-temperature flue gas outlet is lower, the heat utilization rate of the flue gas is improved, and the energy consumption of cooling, dehydrating, compressing and condensing links is reduced.
4. A large amount of N is needed in the steel production process 2 Serving as protective gas, and simultaneously preparing N by air separation device 2 And O 2 Has good economic effect.
Drawings
FIG. 1 is a schematic diagram of a low-carbon total oxygen blast furnace ironmaking process flow.
Reference numerals illustrate: 1. the device comprises a blast furnace body, an oxygen-enriched combustion device, a primary heat exchange device, a secondary heat exchange device, a tertiary heat exchange device, a pressure swing adsorption device, an air separation device, a cooling and dewatering device, a compression condensing device and a carbon dioxide storage device.
Detailed Description
Example 1
The Aspen Plus is used for simulation calculation, the oxygen is 100% pure oxygen, circulating top gas and pure oxygen are blown into a hearth tuyere, high-temperature flue gas is blown into a furnace body, and the production indexes are as follows:
furnace top gas amount: 1363Nm 3 /tHM
Circulating furnace top gas amount: 928Nm 3 /tHM
Oxygen-enriched combustion furnace top gas volume: 296Nm 3 /tHM
External supply of furnace top gas volume: 139Nm 3 /tHM
Oxygen consumption: 314Nm 3 tHM (blast furnace charging), 102Nm 3 tHM (oxygen enriched combustion)
Temperature of circulating furnace top gas when it is blown into the blast furnace: 1300 DEG C
Temperature of oxygen when it is blown into the blast furnace: 1300 DEG C
Temperature of high temperature flue gas blown into the furnace body: 1801 DEG C
The amount of high temperature flue gas blown into the furnace body: 47.62Nm 3 /tHM
Top furnace gas composition: CO:50.99, CO 2 ：39.11％，H 2 ：8.81％，N 2 ：0.73％，CH 4 ：0.36％
Circulating top gas composition blown into the blast furnace: CO:80.45%, CO 2 ：4.5％，H 2 ：13.4％，N 2 ：1.04％，CH 4 ：0.6％
The ratio of the oxygen-enriched combustion circulating smoke is: 40 percent of
Low temperature flue gas exhaust temperature: 185 DEG C
CO capture 2 The amount is as follows: 257Nm 3 /tHM
At this time, the residual gas amount of the whole system was 139Nm 3 The tHM can be supplied externally.
Example 2
In the case of example 1, the circulating furnace roof gas amount was increased and simulated calculations were performed using Aspen Plus, the production index of which was as follows:
furnace top gas amount: 1493Nm 3 /tHM
Circulating furnace top gas amount: 1180Nm 3 /tHM
Oxygen-enriched combustion furnace top gas volume: 342Nm 3 /tHM
External supply of furnace top gas volume: 0Nm 3 /tHM
Supplementing the gas quantity: 29Nm 3 /tHM
Oxygen consumption: 284Nm 3 tHM (blast furnace charging), 122Nm 3 tHM (oxygen enriched combustion)
Temperature of circulating furnace top gas when it is blown into the blast furnace: 1300 DEG C
Temperature of oxygen when it is blown into the blast furnace: 1300 DEG C
Temperature of high temperature flue gas blown into the furnace body: 1869 DEG C
The amount of high temperature flue gas blown into the furnace body: 54.47Nm 3 /tHM
Top furnace gas composition: CO:54.05, CO 2 ：35.57％，H 2 ：9.12％，N 2 ：0.93％，CH 4 ：0.33％
Circulating top gas composition blown into the blast furnace: CO:81.34, CO 2 ：3.67％，H 2 ：13.23％，N 2 ：1.28％，CH 4 ：0.49％
The ratio of the oxygen-enriched combustion circulating smoke is: 40 percent of
Low temperature flue gas exhaust temperature: 200 DEG C
CO capture 2 The amount is as follows: 294Nm 3 /tHM
At this time, the heat generated by the oxygen-enriched combustion of the non-circulated top gas is insufficient to preheat the circulated top gas and oxygen blown into the blast furnace to 1300 ℃, and the oxygen-enriched combustion device needs to be supplemented with 29Nm of fuel gas from the outside 3 the/tHM either reduces the temperature of the recycled top coal and oxygen blown into the blast furnace.
Example 3
In the case of example 2, the circulating furnace roof gas amount was further increased, and a simulation calculation was performed using Aspen Plus, the production index of which was as follows:
furnace roofGas amount: 1470Nm 3 /tHM
Circulating furnace top gas amount: 1265Nm 3 /tHM
Oxygen-enriched combustion furnace top gas volume: 357Nm 3 /tHM
External supply of furnace top gas volume: 0Nm 3 /tHM
Supplementing the gas quantity: 152Nm 3 /tHM
Oxygen consumption: 274Nm 3 tHM (blast furnace charging), 126Nm 3 tHM (oxygen enriched combustion)
Temperature of circulating furnace top gas when it is blown into the blast furnace: 1300 DEG C
Temperature of oxygen when it is blown into the blast furnace: 1300 DEG C
Temperature of high temperature flue gas blown into the furnace body: 1834 DEG C
The amount of high temperature flue gas blown into the furnace body: 57.22Nm 3 /tHM
Top furnace gas composition: CO:55.15, CO 2 ：36.78％，H 2 ：6.93％，N 2 ：0.95％，CH 4 ：0.20％
Circulating top gas composition blown into the blast furnace: CO:83.35, CO 2 ：3.84％，H 2 ：11.10％，N 2 ：1.40％，CH 4 ：0.31％
The ratio of the oxygen-enriched combustion circulating smoke is: 40 percent of
Low temperature flue gas exhaust temperature: 207 DEG C
CO capture 2 The amount is as follows: 309Nm 3 /tHM
At this time, the heat generated by the oxygen-enriched combustion of the non-circulated top gas is insufficient to preheat the circulated top gas and oxygen blown into the blast furnace to 1300 ℃, and the oxygen-enriched combustion device needs to be supplemented with 152Nm of fuel gas from the outside 3 the/tHM either reduces the temperature of the recycled top coal and oxygen blown into the blast furnace.
By three examples, it can be seen that as the amount of recycled top gas increases, the quality of top gas produced by the blast furnace increases and the trapped CO 2 The amount increases; the oxyfuel combustion device also consumes more gas to provide enough heat to preheat the circulating top coal and oxygen blown into the blast furnace to the required temperature, which is then requiredAnd supplementing coal gas from the outside into the oxygen-enriched combustion device.
Claims (2)
1. The low-carbon total-oxygen blast furnace ironmaking process is characterized by comprising a blast furnace body, an oxygen-enriched combustion device, a primary heat exchange device, a secondary heat exchange device, a tertiary heat exchange device, a pressure swing adsorption device, an air separation device, a cooling dehydration device, a compression condensing device and a carbon dioxide storage device;
the process comprises the following steps:
the air enters the air separation device to be separated, and the produced pure oxygen is separated into first pure oxygen and second pure oxygen;
the top gas led out from the blast furnace body is divided into a first top gas, a second top gas and a third top gas;
the first furnace top gas is sent into the oxygen-enriched combustion device for combustion, and the generated high-temperature flue gas is divided into first high-temperature flue gas and second high-temperature flue gas;
the first high-temperature flue gas is blown into a blast furnace from the furnace belly part of the blast furnace body and is used for preheating materials;
the second high-temperature flue gas sequentially flows through the primary heat exchange device, the secondary heat exchange device and the tertiary heat exchange device and is used for preheating the second top gas and the first pure oxygen;
the first pure oxygen is preheated by the three-stage heat exchange device, the second-stage heat exchange device and the first-stage heat exchange device in sequence and then is blown into the blast furnace from a hearth tuyere of the blast furnace body;
the second top gas is firstly sent into the pressure swing adsorption device to remove CO 2 Then sequentially flowing through the secondary heat exchange device and the primary heat exchange device for preheating, and finally blowing the air into the blast furnace from a hearth tuyere of the blast furnace body;
the third top gas is externally supplied;
the low-temperature flue gas from the three-stage heat exchange device is sent to the cooling and dehydrating device for dehydration, and the dehydrated low-temperature flue gas is divided into a first low-temperature flue gas and a second low-temperature flue gas;
the first low-temperature flue gas is sent to the compression condensing device, compressed and condensed into liquid state and then stored in the carbon dioxide storage device;
the second low-temperature flue gas is mixed with the second pure oxygen to form O 2 /CO 2 The circulating flue gas is sent into the oxygen-enriched combustion device to be mixed and combusted with the first furnace top gas;
the oxygen purity of the first pure oxygen and the second pure oxygen is not less than 95%;
the volume ratio of the first furnace top gas in the furnace top gas led out of the blast furnace body is 20-30%, the volume ratio of the second furnace top gas is 60-90%, and the balance is the third furnace top gas;
the O is 2 /CO 2 In the circulating flue gas, the volume ratio of the second low-temperature flue gas is 70-75%, and the volume ratio of the second pure oxygen is 25-30%;
in the high-temperature flue gas generated by the oxygen-enriched combustion device, the volume ratio of the first high-temperature flue gas is 5-10%, and the balance is the second high-temperature flue gas;
low-temperature flue gas CO coming out of three-stage heat exchange device 2 The concentration is not lower than 85 percent, and the temperature is 160-220 ℃;
the temperature of the first pure oxygen and the second top gas is 1200-1300 ℃ when the first pure oxygen and the second top gas are blown into the blast furnace from a hearth tuyere of the blast furnace body.
2. The low carbon total oxygen blast furnace ironmaking process of claim 1, wherein when the volume ratio of the second top gas is high enough that the heat generated by the combustion of the first top gas in the oxyfuel combustion device is insufficient to preheat the first pure oxygen and the second top gas to 1200 ℃ to 1300 ℃, the external supplementary gas enters the oxyfuel combustion device to combust the supplementary heat.
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