Improved hydrogen-rich smelting blast furnace carbon reduction method and blast furnace body structure

Abstract

The invention discloses an improved carbon reduction method for a hydrogen-rich smelting blast furnace and a blast furnace body structure, relates to the technical field of hydrogen-rich smelting blast furnaces, and aims to solve the problem that the difference between the actual carbon reduction effect and the theoretical carbon reduction effect is large. A part of hydrogen-rich gas is uniformly injected into the dripping area of the blast furnace from the periphery of the tuyere of the hearth, the injection speed is high, the injection quantity is low, and the hydrogen-rich gas is controlled to react completely and is prevented from escaping into top gas; the other part of hydrogen-rich gas is blown into the root area of the soft melting zone from the bosh area in a multi-point dispersion mode, the blowing speed is low, the blowing amount is large, and the hydrogen-rich gas is evenly distributed in the area as far as possible and makes full contact with the materials; two parts of hydrogen-rich gas injection are used for reducing carbon by up to 25% on the premise of not increasing energy consumption; according to the method, carbon can be greatly reduced on the premise that energy consumption is not increased, the hydrogen-rich injection position and key control parameters are determined in the blast furnace body structure in combination with the production rule, universality is high, and certain popularization value is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen-rich smelting blast furnaces, and in particular to an improved carbon reduction method for a hydrogen-rich smelting blast furnace and a blast furnace body structure. Background Art

[0002] Global steel production accounts for about 8% of carbon emissions, while my country's steel industry accounts for 18% of the country's total carbon emissions. Carbon emissions from blast furnace processes account for 70% of the entire steel process. Therefore, in order to achieve carbon peak and carbon neutrality, it is particularly important to reduce carbon emissions from blast furnace processes.

[0003] The hydrogen-rich injection gas for blast furnaces generally refers to one of natural gas, coke oven gas and hydrogen. The theoretical carbon reduction values ​​of the three gas sources are 4%, 6% and 25%, respectively. Based on the traditional iron-making process, the carbon emissions per ton of iron are 1,600 kg. Pure hydrogen can be used as a reducing agent to reduce emissions to 1,200 kg per ton of iron at most.

[0004] At present, the working condition of pure hydrogen source as a reducing agent in domestic blast furnaces is to reduce carbon by about 5% per ton of iron. Because the excess hydrogen is not fully utilized in the blast furnace, it directly escapes to the top gas, causing safety hazards. The actual carbon reduction effect is only 1 / 5 of the theoretical value. Therefore, it is necessary to improve and upgrade the structure of traditional hydrogen-rich blast furnaces to narrow the gap between the working conditions and the theoretical carbon reduction capacity. In summary, an improved method for reducing carbon in hydrogen-rich smelting blast furnaces and a blast furnace body structure are urgently needed to solve this problem. Summary of the invention

[0005] After years of development and improvement, the blast furnace ironmaking process is currently and will be recognized by the industry as the ironmaking equipment with the highest efficiency and the lowest energy consumption. For a long time, affected by the domestic energy structure, the cost of blast furnace hydrogen-rich gas injection is higher than that of solid coal powder injection, causing various scientific research institutions and production companies to abandon the in-depth research and development and application of this technology.

[0006] The hydrogen-rich gas for blast furnace injection generally refers to natural gas, coke oven gas, or hydrogen. Natural gas is a scarce energy source in my country, and the gas for residential use is still insufficient. Coke oven gas is used by almost all steel companies for heating furnaces in the coking process and steel rolling process. The medium that may be used for hydrogen-rich injection in blast furnaces is currently only chemical waste gas or hydrogen or methane separated or synthesized from self-produced coal gas chemical industry. Domestic steel companies generally lack hydrogen-rich gas sources;

[0007] With the increase in the installed capacity of green electricity such as photovoltaic power generation and wind power in my country, and the maturity and development of technologies such as electrolysis for hydrogen production and storage, the energy structure will inevitably change. The cost of hydrogen and hydrogen-rich gas will decline year by year, providing a broad market for the development of hydrogen-rich gas injection technology in blast furnace processes. It is particularly important to tap the potential of the ultimate solid carbon substitution rate of blast furnace hydrogen-rich gas, minimize carbon emissions per ton of iron, and support the country's dual carbon policy.

[0008] The hydrogen reduction can replace the traditional solid carbon by 25% by comprehensive application of blast furnace smelting principle. However, the actual production process is affected by thermodynamics and kinetics. At present, the actual domestic blast furnace can only reach 5%, and there is a large potential. The purpose of the present invention is to provide an improved hydrogen-rich smelting blast furnace carbon reduction method and blast furnace body structure to solve the problem that the actual carbon reduction effect is far from the theoretical one.

[0009] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an improved method for reducing carbon in a hydrogen-rich smelting blast furnace, wherein the blast furnace is divided into five parts from bottom to top: a furnace hearth, a furnace belly, a furnace waist, a furnace body, and a furnace throat; iron-containing furnace charge and coke are loaded from the furnace throat, and are discharged from the furnace through the iron outlet through the charge surface, the block area, the soft melting area, the dripping area, and the accumulation area in sequence; the hot air and coal powder of the blast furnace are burned in the tuyere whirlpool area, and are discharged from the furnace through the dripping area, the soft melting area, and the block area in sequence through the furnace throat; during the process, the iron-containing charge and the high-temperature coal after combustion are discharged from the furnace through the dripping area, the soft melting area, and the block area in sequence; The gas undergoes sufficient heat exchange accompanied by reduction reaction; a part of the hydrogen-rich gas is sprayed evenly from the circumference of the furnace tuyere into the dripping area of ​​the blast furnace, with a high spraying speed and a low volume, to control the complete reaction of the hydrogen-rich gas and avoid escaping into the top coal gas; the other part of the hydrogen-rich gas is sprayed from the belly area into the root area of ​​the soft melting zone at multiple points, with a low spraying speed and a large volume, to make the hydrogen-rich gas as evenly distributed in this area as possible and fully contact with the material; the two parts of hydrogen-rich gas injection are used to reduce carbon by up to 25% without increasing energy consumption.

[0010] Preferably, if pure hydrogen is used, the hydrogen-rich gas sprayed from the furnace tuyere should have a single-gun flow rate of 25 m 3 / min; if coke oven gas is used, the flow rate of a single gun shall be controlled within 15m 3 / min; if natural gas is used, the flow rate of a single gun shall be controlled within 10m 3 / min or less.

[0011] Preferably, the carbon-based substitution rate in the dripping zone is not higher than 10%.

[0012] Preferably, the flow rate of the hydrogen-rich gas sprayed in the furnace bosh area is no higher than 1 / 2 of that of the tuyere spray gun, and the number of the spray ports is more than 3 times that of the furnace tuyere spray gun and is evenly arranged.

[0013] A blast furnace body structure for implementing the above method, wherein a plurality of spray guns 1 are fixedly arranged on the cooling wall in the bosh area of ​​the blast furnace, the spray guns 1 are flush with the cooling wall inlay bricks or spray material, and the muzzles extending into the blast furnace are inclined downward to prevent blockage, and the plurality of spray guns 1 are distributed in an array along the periphery of the blast furnace; a spray gun 2 is correspondingly arranged for each tuyere in the furnace cylinder area, and the number of blowing ports of spray gun 1 is more than 3 times the number of blowing ports of spray gun 2; each spray gun 1 and spray gun 2 are respectively provided with an online flow pressure regulating valve, and the flow rate of spray gun 1 is adjusted to be no higher than 1 / 2 of that of spray gun 2.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This improved hydrogen-rich smelting blast furnace carbon reduction method and blast furnace body structure, through the study of blast furnace ironmaking mechanism, explores the operating space of hydrogen-based reducing agents replacing carbon-based reducing agents, and proposes that the blast furnace ironmaking process can reduce carbon by 25% to the extreme without increasing energy consumption through hydrogen-rich gas injection technology; and combines the production rules in the blast furnace body structure to determine the hydrogen-rich injection position and key control parameters, which has strong universality and certain promotion value; with the increase in the scale of green power installed capacity and the continuous reduction in the cost of electrolytic hydrogen, the economic benefits of blast furnace hydrogen-rich injection technology will be reflected year by year. Therefore, the present invention has certain foresight and guiding significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the blast furnace body structure of the present invention.

[0017] In the figure: 1. accumulation area; 2. whirlpool area; 3. root area of ​​the soft melting zone; 4. belly area; 5. dripping area; 6. soft melting zone; 7. block area; 8. material surface. DETAILED DESCRIPTION

[0018] See also Figure 1 The blast furnace is divided into five parts from bottom to top: the hearth, belly, waist, body and throat. Iron-containing charge and coke are loaded from the throat, and are discharged from the furnace through the material surface 8, block area 7, soft melting area 6, dripping area 5 and accumulation area 1 in turn. The hot air and pulverized coal from the blast furnace are burned in the tuyere whirlpool area 2 and are discharged from the furnace through the throat. During the process, the iron-containing charge and the high-temperature coal gas after combustion undergo sufficient heat exchange and are accompanied by a reduction reaction.

[0019] The average temperature of the charge (containing iron material + coke) at the throat of the blast furnace is about 300℃, and the average temperature of the coal gas (mainly effective component CO) after combustion in the whirlpool zone (hot air + powder spray) at the tuyere position of the hearth is about 2200℃. Hydrogen has a stronger reducing ability than CO in an environment above 810℃, so the position where hydrogen-rich gas is injected into the furnace should be close to the combustion zone. Only when the hydrogen reducing ability is higher than that of CO can it replace C-based reduction without increasing the energy consumption per ton of iron.

[0020] The existing hydrogen-rich injection method is generally to inject from the furnace tuyere and the furnace body, and it is not controlled; although the hydrogen-rich gas is injected into the furnace through the tuyere air supply device and enters the dripping zone, the reverse movement of the reducing gas and the dripping furnace charge causes a short contact time. In addition, the central area of ​​the blast furnace is a non-ore area, and the dynamic conditions of the hydrogen-rich gas in this area are insufficient and the utilization rate is limited. Therefore, a large amount of hydrogen-rich gas escapes into the top gas before being utilized, which is not only wasteful but also causes safety hazards; and injecting into the furnace from the furnace body is even more undesirable, because the average temperature there is insufficient and the hydrogen reduction capacity is limited, so this approach is counterproductive, which leads to the operating condition of the existing technology blast furnace pure hydrogen source as a reducing agent to reduce carbon by about 5% per ton of iron, which is far less than the theoretical data.

[0021] According to the above analysis, combined with Figure 1 The injection positions that meet the condition of using hydrogen to replace C-based reduction without increasing the energy consumption per ton of iron can be divided into two places: the dripping zone and the root zone of the soft melting zone. In order to make full use of these two areas, the present invention proposes an improved method for reducing carbon in hydrogen-rich smelting blast furnaces:

[0022] A part of the hydrogen-rich gas is uniformly sprayed from the furnace tuyere position into the dripping zone 5 of the blast furnace. The temperature in this area is relatively high, and the thermodynamic conditions for the reduction of hydrogen-rich gas are relatively ideal. The hydrogen-rich gas entering this area should be high in speed and low in volume to control the complete reaction of the hydrogen-rich gas and avoid escaping into the top coal gas.

[0023] Another part of the hydrogen-rich gas is sprayed from the furnace belly area 4 at multiple points into the root area 3 of the soft melting zone. The reduction kinetic conditions of the hydrogen-rich gas in this area are ideal. In addition to the high-temperature coal gas in the cyclotron area rising along the furnace wall to this area, there is also a strong furnace center airflow horizontally impacting the furnace wall. The iron-containing furnace charge is relatively concentrated and in a porous solid state. In addition, this area has sufficient heat source and the reaction temperature is also in the hydrogen-rich gas active area. The hydrogen-rich gas has relatively ideal thermodynamic and kinetic conditions in this area. The hydrogen-rich gas in this area should be sprayed at a low speed and a large amount to make the hydrogen-rich gas as evenly distributed in this area as possible and fully contact with the material.

[0024] Two-part hydrogen-rich gas injection is used to reduce carbon emissions by up to 25% without increasing energy consumption.

[0025] The above-mentioned high speed and low volume can refer to the following settings: hydrogen-rich gas sprayed from the furnace tuyere, if pure hydrogen is used, the single-gun flow rate is controlled at 25m 3 / min; if coke oven gas is used, the flow rate of a single gun shall be controlled within 15m 3 / min; if natural gas is used, the flow rate of a single gun shall be controlled within 10m 3 Within / min;

[0026] The aforementioned low speed and large quantity can refer to the following settings: the flow rate of hydrogen-rich gas sprayed in the furnace belly area 4 is not higher than 1 / 2 of the tuyere spray gun, and the number of spray ports is more than 3 times that of the furnace hearth tuyere spray gun and is evenly arranged.

[0027] In addition, the carbon-based substitution rate in the dripping zone 5 should not be higher than 10%, otherwise it is easy to cause a large amount of hydrogen-rich gas to escape into the top coal gas without reaction, causing safety hazards; while the carbon-based substitution rate in the root zone 3 of the soft melting zone can reach up to 15%;

[0028] The best way to replace carbon-based reducing agents with hydrogen-rich gas is to fully combine the respective advantages of the dripping zone 5 and the root zone 3 of the soft melting zone, promote each other synergistically, and achieve the goal of 25% solid carbon replacement rate of blast furnace hydrogen-rich injection.

[0029] To achieve the above goals, the main structure of the blast furnace needs to be improved on the existing basis. Specifically: the cooling wall of the bosh area 4 of the blast furnace is equipped with multiple spray guns 1. Spray gun 1 is flush with the cooling wall inlay bricks or spray material and the muzzle extending into the blast furnace is slanted downward to prevent blockage. Multiple spray guns 1 are distributed in an array along the periphery of the blast furnace; each tuyere in the hearth area is correspondingly provided with a spray gun 2, and the number of blowing ports of spray gun 1 is more than 3 times the number of blowing ports of spray gun 2; each spray gun 1 and spray gun 2 are respectively provided with an online flow pressure regulating valve, and the flow rate of spray gun 1 is adjusted to be no higher than 1 / 2 of spray gun 2.

[0030] Example

[0031] Basic indicators

[0032] Blast furnace capacity 2000m 3 , with 26 air outlets and 2 iron outlets. Air volume 4100m 3 / min (without oxygen), oxygen content 18000m 3 / h, oxygen enrichment rate 5.3%, no humidification, daily output of 7100t of molten steel, fuel consumption (coke ratio 350kg + coal ratio 170kg), carbon emissions per ton of iron 1596kg.

[0033] Key Parameters

[0034] Drop zone: The air supply device of the tuyere uses a sleeve-type spray gun with an outer diameter of D34*2.5mm and an inner diameter of D24*2.5mm. The inner cavity sprays coal and the outer cavity (annular cross section) sprays pure hydrogen. 26 tuyere are used at the same time. The single gun sprays pure hydrogen at a flow rate of 1380m / s (working sound speed 1340m / s), and the flow rate is 18m 3 / min, can achieve 95m3 / ton of iron 3 Pure hydrogen injection rate, carbon consumption replacement rate per ton of iron is 9.5%.

[0035] Soft melting zone root area: There is one layer of nozzles on the furnace belly and under the furnace waist, 2 nozzles for each cooling wall, 42 cooling walls on each layer, 84 nozzles on each layer, single nozzle inner diameter D13mm, 168 nozzles in total for two layers, single gun pure hydrogen flow rate 530m / s, flow rate 4.25m 3 / min, can achieve 145m3 / ton of iron 3 The pure hydrogen injection rate is 14.2% for carbon consumption per ton of iron.

[0036] Each tuyere spray gun for pure hydrogen injection in the dripping zone is equipped with an online flow control valve. The root zone of the soft melting zone uses furnace belly and furnace waist nozzles for pure hydrogen injection. Each cooling wall hydrogen inlet (D34*2.5mm copper tube) is equipped with an online flow control valve, which is divided into two outlets (13mm inner diameter copper tube) in the furnace. The specific injection amount of pure hydrogen in the two areas is fine-tuned in real time by the software based on the actual top gas online measurement of hydrogen utilization rate on the above basis, so as to achieve mutual coordination between the two areas. 3 The amount of hydrogen injected and the fuel consumption (coke ratio 290kg + coal ratio 100kg) reduced the carbon emission per ton of iron to 1220kg, and the replacement rate of carbon consumption per ton of iron was 23.55%.

[0037] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0038] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. An improved method for reducing carbon in a hydrogen-rich smelting blast furnace, wherein the blast furnace is divided into five parts from bottom to top, namely, a furnace hearth, a furnace belly, a furnace body, and a furnace throat. Iron-containing furnace charge and coke are loaded from the furnace throat and sequentially pass through the charge surface (8), the block area (7), the soft melting area (6), the dripping area (5), and the accumulation area (1) and are discharged from the furnace through the tapping port. After the hot air and coal powder of the blast furnace are burned in the tuyere whirlpool area (2), they sequentially pass through the dripping area (5), the soft melting area (6), and the block area (7) and are discharged from the furnace through the furnace throat. During the process, the iron-containing charge and the high-temperature coal gas after combustion undergo sufficient heat exchange and are accompanied by a reduction reaction. The method is characterized in that: A portion of the hydrogen-rich gas is uniformly sprayed from the furnace tuyere position into the blast furnace dripping zone (5) at a high speed and low volume, so as to control the complete reaction of the hydrogen-rich gas and prevent it from escaping into the top coal gas; another portion of the hydrogen-rich gas is dispersedly sprayed from the furnace belly zone (4) into the soft melting zone root zone (3) at multiple points, with a low speed and a large volume, so as to make the hydrogen-rich gas as evenly distributed in this area as possible and fully contact with the material; the two portions of hydrogen-rich gas spraying are used to reduce carbon by up to 25% without increasing energy consumption.

2. The improved method for reducing carbon in a hydrogen-rich smelting blast furnace according to claim 1, characterized in that: If pure hydrogen is used for the hydrogen-rich gas sprayed from the furnace tuyere, the flow rate of a single gun is controlled at 25m 3 / min; if coke oven gas is used, the flow rate of a single gun shall be controlled within 15m 3 / min; if natural gas is used, the flow rate of a single gun shall be controlled within 10m 3 / min or less.

3. The improved method for reducing carbon in a hydrogen-rich smelting blast furnace according to claim 2, characterized in that: The carbon-based substitution rate of the dripping zone (5) is not higher than 10%.

4. The improved method for reducing carbon in a hydrogen-rich smelting blast furnace according to claim 2, characterized in that: The flow rate of the hydrogen-rich gas sprayed in the furnace belly area (4) is no higher than 1 / 2 of that of the tuyere spray gun, and the number of the spray ports is more than 3 times that of the furnace tuyere spray gun and is evenly arranged.

5. A blast furnace body structure for implementing the method according to any one of claims 1 to 4, characterized in that: The cooling wall of the furnace belly area (4) of the blast furnace is fixedly provided with a plurality of spray guns 1, which are flush with the cooling wall inlay bricks or spray materials and the muzzles of which extend into the blast furnace are inclined downward to prevent blockage, and the plurality of spray guns 1 are distributed in an array along the periphery of the blast furnace; a spray gun 2 is correspondingly provided for each tuyere in the furnace cylinder area, and the number of the blowing ports of the spray gun 1 is more than 3 times the number of the blowing ports of the spray gun 2; each spray gun 1 and the spray gun 2 are respectively provided with an online flow pressure regulating valve, and the flow rate of the spray gun 1 is adjusted to be no higher than 1 / 2 of the spray gun 2.

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