CN1216154C

CN1216154C - Blast furnace iron-making technique with hydrogen-rich fuel gas, pure oxygen and thus high efficiency and low CO2 exhaust

Info

Publication number: CN1216154C
Application number: CN031319955A
Authority: CN
Inventors: 李家新; 周莉英
Original assignee: Anhui University of Technology AHUT
Current assignee: Anhui University of Technology AHUT
Priority date: 2003-06-23
Filing date: 2003-06-23
Publication date: 2005-08-24
Anticipated expiration: 2023-06-23
Also published as: CN1487097A

Abstract

The invention provides a high-efficiency low _CO2 emission hydrogen-rich gas pure oxygen blast furnace ironmaking process. The iron-iron process includes injecting hydrogen-rich gas at the tuyere of the blast furnace. The hydrogen-rich gas can be natural gas or coke oven gas. 500-1000m ³ /ton of iron; use normal temperature pure oxygen blast, cancel the hot blast stove of traditional blast furnace; H ₂ content in bosh gas is 30%-60%, the rest is CO; CO+H ₂ content in furnace top gas accounts for 85% -95%; The theoretical combustion temperature is controlled at 1800-2200°C. This ironmaking process can reduce the coke ratio of the blast furnace to below 250kg/ton of iron, the _CO2 emission can be reduced by 400-600kg/ton of iron, and the high calorific value gas produced can be used as secondary energy.

Description

High-efficiency low CO2Blast furnace iron-making process for discharging hydrogen-rich fuel gas and pure oxygen

The technical field is as follows:

the invention belongs to a blast furnace ironmaking process, and particularly relates to a high-efficiency low-CO blast furnace ironmaking process₂Discharge richA hydrogen-gas pure-oxygen blast furnace ironmaking process.

Background art:

CO₂is one of the gases causing the greenhouse effect, and the iron and steel enterprises are CO₂Large house of emissions, in which the blast furnace is CO in the steel industry₂Is mainly generated. In the traditional blast furnace iron-making process, coke is generally used as a main fuel (the coke ratio is 400 plus one ton of iron) and pulverized coal is injected in an auxiliary mode to reduce the coke ratio (the coal ratio is 0-150kg per ton of iron), hot air is blown at an air port (the air temperature is 1000 plus one ton of iron), a small amount of oxygen is enriched in the air, the oxygen enrichment rate is generally 0-5%, and the discharged blast furnace gas has a certain heat value (3000 plus one ton of iron 4500 kJ/m)³) But the calorific value is not high, and the coal gas is generally mixed with coke oven gas to be used for burning hot blast stoves. The coke or coal powder added into the blast furnace is finally mixed with CO₂The emission amount is about 1400 kg/ton of iron, and the emission amount accounts for CO per ton of steel in the steel industry₂More than half of the discharge amount. At present, in the metallurgical industry at home and abroad, the total energy consumption of the working procedures is mainly reduced to reduce the CO of the blast furnace₂Emission, but not change the fuel structure of the blast furnace, only by the improvement of the process and the equipment to reduce CO₂Is very limited.

The iron-making process concerned by the domestic and foreign metallurgical industry also comprises a total oxygen blast furnace. Blast furnace total oxygen blast or with high oxygen concentration (with O)₂More than 40%) to promote the combustion of a large amount of coal powder, and can raise the coal injection quantity to over 300 kg/ton of iron under the condition of high conversion ratio, so that the coke ratio is greatly reduced, and the coal powder consumption exceeds the coke consumption to become the main energy source for blast furnace ironmaking, and it is a smelting process between melting reduction and traditional blast furnace process. The total oxygen blast furnace has two technical problems to be solved, namely insufficient heat at the upper part of the blast furnace and overhigh temperature of a tuyere, and the method for solving the problems mainly comprises the following steps: the method of adopting a tuyere to spray a coolant to adjust down heat, solving the problem of cooling up by spraying coal gas on a furnace body, and providing a total oxygen blast furnace process with the functions of removing carbon dioxide from the coal gas, heating and spraying the furnace body, but the complex process and equipment investment become an obstacle for developing the oxygen coal furnace process. The research of the total oxygen blast furnace process without blowing and purifying coal gas of the furnace body is carried out in 90 s, and the furnace body blowing is cancelledAfter the gas is blown, a 'high oxygen-rich' large-blowing blast furnace appears, furnace top gas is circularly blown to the total-oxygen blast furnace, and some regulating measures are accompanied by blowing water vapor or heating and blowing gas at a tuyere and the like. In a word, the blastfurnace process with oxygen enrichment and total oxygen is an iron-making process taking coal as main energy, and the carbon dioxide emission of the blast furnace is difficult to be effectively reduced.

The invention content is as follows:

the invention aims to provide a high-efficiency low-CO₂A blast furnace ironmaking process discharging hydrogen-rich fuel gas and pure oxygen. Aiming at the purposes, the blast furnace ironmaking process provided by the invention mainly comprises the following technical contents: injecting hydrogen-rich gas at the blast furnace tuyere, wherein the hydrogen-rich gas can be natural gas or coke oven gas, and the injection amount is 500-³Per ton of iron; pure oxygen blast is adopted at normal temperature; h in furnace gas₂30-60% of the total weight of the composition, and the balance of CO; the coke ratio of the blast furnace is reduced to below 250 kg/ton iron; CO + H in top gas₂The content is 85-95%; the theoretical combustion temperature is controlled at 1800-2200 ℃; blast furnace CO₂The discharge amount is reduced by 400-600 kg/ton iron.

The schematic diagram of the ironmaking process is shown in the attached figure 1 of the specification.

Injecting hydrogen-rich gas (natural gas or coke oven gas) into a blast furnace tuyere, firstly cracking the natural gas or coke oven gas in the tuyere area of the blast furnace, and carrying out combustion reaction with oxygen:

if water is present, there is water gas reactionIt should happen that:

the reaction produces reducing gases CO and H₂. Because the blast is pure oxygen, the furnace gas is mainly CO and H₂In which H is₂The content can reach or be higher than 30-60%, and the volume of the coal gas in the furnace cavity is not greatly increased compared with that of the traditional blast furnace; the theoretical combustion temperature is reduced because the cracking of the hydrogen-rich gas in the air inlet area needs to absorb partial heat, but the theoretical combustion temperature can be controlled by adjusting parameters such as comprehensive coke ratio, the injection amount of the hydrogen-rich gas, the blast humidity and the like, so that the theoretical combustion temperature is in the range of 1800 plus one minus one plus. Although the quality of the molten iron is reduced compared with the traditional blast furnace, the production of the blast furnace and the quality of the molten iron are not influenced.

Because the concentration of the reducing gas in the blast furnace is high, the ore is added with CO and H₂Reduction reaction occurs:

CO reduction:

indirect reduction:

direct reduction:

H₂reduction:

under the condition of high-hydrogen-content coal gas, hydrogen can participate in the reduction process of ores in a large amount, the reduction of iron ores in the blast furnace is greatly enhanced, and the ores are fully reduced in the blast furnace quickly.

The ironmaking process provided by the invention has the advantages that:

1. the smelting effect comparison shows that the process has the distinct characteristics that:

(1) the coke ratio can be greatly reduced;

(2) compared with a total oxygen blast furnace, the technology of injecting natural gas is adopted, so that the contradiction that the theoretical combustion temperature of the tuyere of the pure oxygen blast furnace is too high and the quantity of coal gas of the blast furnace is slightly less and the heat quantity on the upper part of the blast furnace is insufficient is effectively solved. The theoretical combustion temperature of the tuyere can be adjusted more flexibly, the gas quantity is sufficient, and compared with the traditional blast furnace, the theoretical combustion temperature of the tuyere has no great difference in the aspect.

(3) As the hydrogen content in the coal gas in the furnace exceeds 30-60%, the smelting efficiency of the blast furnace is greatly improved, and the utilization coefficient of the blast furnace can be further improved. The output of the blast furnace with the samevolume can be greatly improved.

2. The high-efficiency low-coke ratio hydrogen-rich pure oxygen blast furnace process can reduce CO₂And (5) discharging.

In the process provided by the invention, because high-concentration hydrogen participates in the reaction and the heating of a hot blast stove is cancelled, the emission of carbon dioxide in the blast furnace smelting process is effectively reduced.

Taking example 1 (coke ratio: 220 kg/ton iron, coal ratio 154 kg/ton iron): in the process, hydrogen participates in reduction to replace carbon: 138 kg/ton iron; reduced CO emissions₂：257m³Per ton of iron (about 505kg per ton of iron).

3. From the aspect of economic competitiveness, the high-efficiency low-coke ratio hydrogen-rich pure oxygen blast furnace process has good resource utilization compatibility

Furnace top gas CO + H generated by high-efficiency low-coke-ratio hydrogen-rich pure oxygen blast furnace₂Content of 85-95%, H₂The content of the coal gas is about 50 percent of the top gas, and the heat value reaches 10000kJ/m³The above. The high-calorific-value coal gas can be used as a secondary energy source or a raw material of a chemical plant. The attached figure 2 of the specification is that natural gas (coke oven gas) is used for a high-efficiency low-coke-ratio hydrogen-rich pure oxygen blast furnace ironmaking process and the original purposeThe process is compared with the schematic diagram, and the process can be seen in fact that the full utilization of hydrogen-rich fuel gas such as natural gas, coke oven gas and the like is considered from a larger range from the perspective of improving the efficiency of the metallurgical process, the coke coal resource is saved, the production efficiency of the blast furnace is improved, and the resource utilization and the control of greenhouse gas emission are comprehensively considered from a source and in a larger range.

4. The traditional hot blast stove is cancelled, the flow is simplified, and the equipment investment is reduced

Because the process blows pure oxygen at normal temperature, a hot blast stove in the traditional iron making process is omitted, the process is simplified, and the investment of equipment is reduced.

Description of the drawings:

FIG. 1 is a schematic diagram of a blast furnace ironmaking process using hydrogen-rich fuel gas and pure oxygen.

Fig. 2 is a schematic diagram comparing a conventional application mode and a comprehensive utilization mode of the hydrogen rich fuel gas.

The specific implementation mode is as follows:

example 1:

at a certain 350m³The blast furnace tuyere blows natural gas and coal powder, and blows pure oxygen, and the production index is as follows:

the natural gas injection amount is as follows: 800m³Ton iron (i.e. 574 kg/ton iron)

Coke ratio: 220 kg/ton iron

Coal ratio: 154 kg/ton iron

Amount of pure oxygen consumed: 612m³Ton iron (874 kg/ton iron)

The coal gas composition of the furnace chamber: h₂：57％；CO：43％

Theoretical combustion temperature: 2006 deg.C

The components of the top gas: CO: 37 percent; CO 2₂：10.2％；H₂：52.5％；N₂：0.26％；S：0.05％

The amount of the top gas: 2607m³Ton iron (amounting to 1869 kg/ton iron)

Example 2:

at a certain 350m³The blast furnace tuyere blows natural gas, coke oven gas and coal powder and blows pure oxygen, and the production index is as follows:

the natural gas injection amount is as follows: 500m³Ton iron (i.e. 359 kg/ton iron)

Coke oven gas injection amount: 270m³Ton iron (i.e. 103 kg/ton iron)

Coke ratio: 200 kg/ton iron

Coal ratio: 160 kg/ton iron

Amount of pure oxygen consumed: 500m³Ton iron (i.e. 715 kg/ton iron)

Gas composition of furnace bosh, H₂：57.2％；CO：42.8％

Theoretical combustion temperature: 2149 deg.C

The components of the top gas: CO: 35.3 percent; CO 2₂：12.7％；H₂：51.6％；N₂：0.33％；S：0.06％

The amount of the top gas: 2130m³Ton iron (converted 1589 kg/ton iron)

Claims

1. A high-efficiency low _CO2 emission hydrogen-rich gas pure oxygen blast furnace ironmaking process, characterized in that hydrogen-rich gas is injected at the tuyere of the blast furnace, the hydrogen-rich gas is natural gas or coke oven gas, and the injection volume is ^500-1000m3 / ton of iron; normal temperature pure oxygen blast is used; the _H2 content in the bosh gas is 30% to 60%, and the rest is CO; the theoretical combustion temperature is controlled at 1800-2200°C; the blast furnace coke ratio is reduced to below 250kg/ton of iron.