CN114657316A - Method for fixing carbon in evaporative cooling flue of metallurgical furnace - Google Patents

Abstract

The invention provides a method for carbon fixation in the vaporization cooling flue of a metallurgical furnace. In the method, an injection system is added to the vaporization cooling flue of the metallurgical furnace, and before the metallurgical flue gas is dedusted, 100-300 mesh lime powder or slaked lime powder is directly injected into the vaporization cooling flue, and the waste heat of the metallurgical furnace flue gas is used for energy supply. , the injected lime powder or slaked lime powder reacts with the CO ₂ in the flue gas to solidify into CaCO ₃ , and the unreacted lime powder or slaked lime powder and the generated CaCO ₃ are mixed with the dust removed for collection; the metallurgical flue gas after carbon fixation for recycling. The invention uses the vaporization cooling flue as the reactor, and by controlling the particle size and injection amount of the lime powder or slaked lime powder, green recycling of the metallurgical furnace flue gas can be realized, and the separated flue dust can also be directly used for steel-making balls The preparation of briquettes provides an effective way for the sustainable and economical production of the metallurgical industry.

Description

Method for fixing carbon in vaporization cooling flue of metallurgical furnace

technical field

The invention relates to the technical field of metallurgical energy saving and environmental protection, in particular to a method for carbon fixation in a vaporization cooling flue of a metallurgical furnace.

Background technique

Metallurgical gas is a flammable mixed gas containing a large amount of CO produced in the process of steelmaking, ironmaking, coking, generator and ferroalloy production. The composition of the gas is generally affected by the raw materials for gas production and the production and recovery process of the gas, and its composition and the percentage of the corresponding components are also different. Common types of metallurgical gas include coke oven gas, producer gas, blast furnace gas, converter gas Gas, ferroalloy gas.

The main pollutants of metallurgical gas are: gas containing sulfur dioxide, gas containing fluorine, gas containing dust, gas containing nitrogen oxides, etc. Metallurgical waste gas has a large amount of emissions and a wide range of pollution; the temperature is high, the composition is complex, the dust particles are fine, and the adsorption force is strong; the waste gas has high recovery value.

At present, the way of using metallurgical gas in metallurgical industry mostly focuses on the utilization of high calorific value components (CO, H ₂ , CH ₄ ), such as metallurgical furnace baking, as fuel for power generation. For other components, they are mostly released into the air after simple treatment. Among them, CO ₂ is difficult to be completely treated, which seriously pollutes the environment and is not conducive to the achievement of the double-carbon goal.

During the working period of the metallurgical furnace, the metallurgical furnace usually produces >70m3 ^of metallurgical furnace gas per ton of molten steel; the carbon in the molten iron reacts with oxygen during the steelmaking process of the metallurgical furnace to generate carbon monoxide, and a small amount of carbon is also directly oxidized to carbon dioxide; carbon-oxygen reaction The resulting mixed gas containing CO, CO ₂ , N ₂ and the like is called metallurgical furnace gas. Due to the uneven generation of metallurgical furnace gas, the composition also changes. Usually, the coal gas recovered from the multiple smelting process of the metallurgical furnace is input into a gas storage tank, mixed evenly and then delivered to the user. Therefore, when the carbon monoxide concentration is low in the later stage before the blowing of the metallurgical furnace, it will be released by the combustion of the release chimney. At present, the basic conditions of metallurgical furnace gas recovery are mostly: CO≥35%, O ₂ <1.5%.

When the metallurgical furnace gas is ejected from the furnace mouth, the temperature is as high as 1200-1600 ℃, and a large amount of iron oxide dust is entrained. It can only be used after cooling and dust removal. But no matter which method is adopted, after the gas leaves the metallurgical furnace, the oxygen content in the metallurgical furnace gas is not easy to control and contains relatively high CO ₂ .

The precondition for the recovery of metallurgical furnace gas is not only to ensure that the dust removal system is in good operation, to efficiently capture the dust particles in the flue gas of the metallurgical furnace, so that the quality of the gas meets the needs of users, but also to ensure the content of carbon monoxide, so that the recovered gas can be recovered. The unit calorific value in gas is high. More importantly, it is necessary to control the oxygen content in the gas beyond the explosion limit. According to the requirements of the safety regulations for the recovery of metallurgical furnace gas, the gas should be released when the oxygen volume content is greater than 2%, and it can be carried out when the oxygen volume content is less than 2%. Recycling, in order to achieve the purpose of ensuring gas quality and safe recycling.

In view of this, it is necessary to design an improved method for carbon fixation in the vaporization and cooling flue of metallurgical furnaces, and at the same time realize the green recovery of metallurgical furnace flue gas and the recycling of metallurgical furnace dust, so as to solve the above problems.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a method for carbon fixation in the vaporization cooling flue of a metallurgical furnace. In the method, 100-300 mesh lime powder or slaked lime powder is directly sprayed into the vaporization cooling flue, the waste heat of the metallurgical furnace flue gas is used, the unreacted lime powder or slaked lime powder is mixed with the dedusted fume and dust, and the solidified metallurgical flue gas is dedusted. Recycling, so as to realize the green utilization of metallurgical furnace flue gas and the high-value utilization of metallurgical dust, provide an effective way for the sustainable and economical production of the metallurgical industry.

In order to achieve the above purpose of the invention, the present invention provides a method for carbon fixation in the vaporization cooling flue of a metallurgical furnace, adding an injection system on the vaporization cooling flue of the metallurgical furnace, including the following steps: the metallurgical furnace gas in the metallurgical furnace smelting During recovery, the lime powder or slaked lime powder is injected into the vaporization cooling flue through the injection system; the lime powder or slaked lime powder utilizes the waste heat of the metallurgical furnace flue gas to supply energy to complete the solidification of the lime powder or slaked lime powder CO ₂ ; The remaining lime powder or slaked lime powder is mixed and collected with the smoke and dust separated from the flue gas of the metallurgical furnace. After carbon fixing, the metallurgical flue gas is dedusted and recycled.

As a further improvement of the present invention, the lime powder or slaked lime powder is sprayed at 1-30 kg/t steel.

As a further improvement of the present invention, the lime powder or slaked lime powder is used for the preparation of steel-making pellets together with the smoke and dust separated from the flue gas of the metallurgical furnace.

As a further improvement of the present invention, the particle size of the lime powder or slaked lime powder is less than 0.075mm.

As a further improvement of the present invention, the particle size of the lime powder or slaked lime powder is 0.025-0.075 mm.

As a further improvement of the present invention, the carrier gas injected by the lime powder or slaked lime powder is an inert gas or a conventional vaporizing agent.

As a further improvement of the present invention, the inert gas is nitrogen; the conventional vaporizing agent is CO ₂ or water vapor.

As a further improvement of the present invention, the flow rate of the carrier gas is 20-200 m ³ /kg lime powder or slaked lime powder.

As a further improvement of the present invention, the blowing system includes a blowing pipe, a powder spraying tank communicated with the blowing pipe, and a spray gun arranged in the vaporization cooling flue, the spray gun being communicated with the blowing pipe; The powder spraying tank is used for accommodating the lime powder or slaked lime powder, the carrier gas is sprayed from the jet pipe, and carries the lime powder or the slaked lime powder together through the spray gun and sprayed into the vaporization cooling flue .

As a further improvement of the present invention, the spray gun is arranged at the front end of the flue gas dust removal equipment, and the end of the conveying pipe after the vaporization and cooling flue is sprayed and cooled, and the spray gun is perpendicular to the side wall of the vaporization and cooling flue.

The beneficial effects of the present invention are:

1. the method for carbon fixation in metallurgical furnace vaporization cooling flue provided by the present invention, by adding injection system on the vaporization cooling flue of metallurgical furnace, when metallurgical furnace gas in metallurgical furnace smelting is recovered, will be less than 200 purpose lime powder. Or slaked lime powder is directly sprayed into the vaporization cooling flue, and the waste heat from the flue gas of the metallurgical furnace is used to power the lime powder or slaked lime powder to solidify the CO ₂ in the metallurgical flue gas. After the flue gas is recycled. In this way, the vaporization cooling flue is used as the reactor, and by controlling the particle size and injection amount of lime powder or slaked lime powder, the efficient recovery and utilization of metallurgical furnace flue gas heat and metallurgical furnace gas can be achieved. Disperse in the air, use lime powder or slaked lime powder to solidify CO ₂ in the vaporization flue of metallurgical furnace, without additional heat source; lime powder or slaked lime powder to solidify carbon dioxide can reduce the concentration of carbon dioxide in high temperature flue gas of metallurgical furnace, the smaller the carbon dioxide concentration, the lower the carbon dioxide concentration. The higher the calorific value of the metallurgical flue gas in the later stage, the higher the gas value; at the same time, it can also meet the purpose of carbon reduction in iron and steel enterprises, and the separated flue dust can also be directly used for the preparation of steel-making pellets, which is an important part of the metallurgical furnace steel-making industry. Sustainable and economical production provides an effective way.

2. The method for fixing carbon in the vaporization cooling flue of a metallurgical furnace provided by the present invention adopts lime powder or slaked lime powder to be directly sprayed into the vaporization cooling flue, which will not cause blockage to the vaporization cooling flue, because it is directly in contact with the flue gas. Due to the high utilization rate of lime; on the other hand, the improvement method of the metallurgical furnace smelting system is simple, adding a simple lime powder or slaked lime powder injection system to the original gas purification and recovery system, using the pneumatic conveying technology, the powder spraying tank used And the spray gun technology is relatively mature, and there is no need to change the overall line of the metallurgical furnace smelting system, such as the soot separation line and the gas release and recovery line. Therefore, practicality is strong.

Description of drawings

FIG. 1 is a schematic diagram of the device structure of the method for carbon fixation in the vaporization cooling flue of a metallurgical furnace according to the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to specific embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and/or processing steps closely related to the solution of the present invention are shown in the specific embodiments, and the Other details not relevant to the invention.

In addition, it should be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Also included are other elements not expressly listed or inherent to such a process, method, article or apparatus.

The following are preferred embodiments of the present invention.

The lime powder or slaked lime powder adopted in the embodiment of the present invention is ordinary industrial lime powder or slaked lime powder.

Example 1

The converter used for smelting is a 100t converter, the lime used is ordinary lime, and the lime is pulverized to a particle size below 300 mesh (particle size 0.048mm), and the moisture content in the material is less than 1% by weight.

When the converter gas is recovered, the pulverized lime powder is injected into the vaporization cooling flue, and the injection carrier gas is nitrogen, wherein the flow rate of nitrogen is 0.1m ³ /2kg lime powder, and the injection amount of lime powder is 20kg/m ³ Converter gas.

The lime powder is blown into the vaporization and cooling flue through a spray gun, and the spray gun is arranged on the vaporization and cooling flue. The distance between the spray gun and the converter furnace mouth is 2/3 of the length of the vaporization and cooling flue.

Carry out 10 tests according to the above method, and detect and analyze the collected metallurgical dust. The utilization rate of CaO reaches 90%. The main components of the recovered gas are CO 76-83%, CO ₂ 1-5%, O ₂ 0.2～0.3%. The main components of the coal gas recovered without blowing lime powder are CO 45-60%, CO ₂ 10-25%, and O ₂ 0.6-0.9% by volume percentage.

Compared with the prior art, the use of the present invention can reduce the CO ₂ content by more than 90%, and at the same time, the use of the present invention can also achieve the effect of carbon sequestration of more than 85% for ordinary grade lime.

Example 2

The converter used in the smelting is a 60t converter, the slaked lime powder used has a particle size of less than 300 meshes, and the moisture content of the slaked lime powder is less than 1% by weight.

When the converter flue gas is recovered, the slaked lime powder is injected into the vaporization cooling flue, and the injection carrier gas is nitrogen, wherein the flow rate of nitrogen is 0.15m ³ /1kg slaked lime powder, and the injection amount of slaked lime powder is 20kg/m ³ converter smoke gas.

The slaked lime powder is blown into the vaporization cooling flue through a spray gun, and the spray gun is arranged on the vaporization cooling flue. The distance between the spray gun and the converter furnace mouth is 1/3 of the length of the vaporization cooling flue.

Carry out 10 tests according to the above method, and detect and analyze the collected metallurgical dust. The utilization rate of CaO reaches 93%. The main components of the recovered gas are CO 79-82%, CO ₂ 1-4%, O ₂ 0.2～0.3%. The main components of the gas recovered without blowing slaked lime powder are CO 45-60%, CO ₂ 10-25%, and O ₂ 0.6-0.9% by volume percentage.

Compared with the prior art, the use of the present invention can reduce the CO ₂ content by more than 92%, and at the same time, the use of the present invention can also achieve the effect of carbon sequestration of more than 85% for ordinary grade slaked lime.

Example 3

The converter used for smelting is a 40t converter, and the lime powder or slaked lime powder used is the lime powder crushed to a particle size below 300 mesh, and the moisture content of the lime powder or slaked lime powder is less than 1% by weight.

When the converter flue gas is recovered, the lime powder is injected into the vaporization cooling flue, the injection carrier gas is nitrogen, and the flow rate of nitrogen is 0.15m ³ /1kg lime powder or slaked lime powder or slaked lime powder The injection amount is 20kg /m ³ converter flue gas.

The lime powder is blown into the vaporization cooling flue through a spray gun, and the spray gun is arranged on the vaporization cooling flue. The distance between the spray gun and the converter furnace mouth is 1/3 of the length of the vaporization cooling flue.

Carry out 10 tests according to the above method, and detect and analyze the collected metallurgical dust. The utilization rate of CaO reaches 88%. The main components of the recovered gas are CO 75-83%, CO ₂ 1-4%, O ₂ 0.2～0.3%. The main components of the coal gas recovered without blowing lime powder are CO 45-60%, CO ₂ 10-25%, and O ₂ 0.6-0.9% by volume percentage.

Compared with the prior art, the use of the present invention can reduce the CO ₂ content by more than 89%, and at the same time, the use of the present invention can also achieve the effect of carbon sequestration by more than 85% for ordinary grade lime.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and/or processing steps closely related to the solution of the present invention are shown in the specific embodiments, and the Other details not relevant to the invention.

In addition, it should be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Also included are other elements not expressly listed or inherent to such a process, method, article or apparatus.

The vaporization cooling flue of the metallurgical furnace has the functions of collecting, cooling and conveying the flue gas. In addition, the vaporization cooling flue is also a waste heat boiler for producing steam. Evaporation cooling is a device that uses softened water to cool iron and steel metallurgical equipment in a vaporized manner (taking full advantage of the large latent heat of water vaporization) and absorb a large amount of heat to generate steam.

The lime powder or slaked lime powder is blown at 1-30kg/t steel, preferably 10-25kg/t steel, more preferably 20kg/t steel. Experiments of the invention show that by controlling the injection amount of lime powder or slaked lime powder with ton of steel as the standard, the optimal recovery of metallurgical furnace flue gas heat and metallurgical furnace gas can be achieved, that is, the heat utilization rate and lime powder or slaked lime can be obtained. The powder decomposition efficiency is the highest, and the recovery of metallurgical furnace gas and the calorific value of combustion are optimal.

Lime powder or slaked lime powder can be used in the preparation of steelmaking pellets together with the fumes separated from the flue gas of metallurgical furnaces. In this way, the sustainable and economical production of the metallurgical furnace steelmaking industry can be realized, and the production cost of the metallurgical furnace steelmaking can be greatly reduced.

The particle size of lime powder or slaked lime powder is less than 0.075mm, that is, passing through a 200-mesh sieve, preferably 0.025-0.075mm. The lime powder or slaked lime powder is ordinary industrial lime powder or slaked lime powder. The use of small particle size lime powder or slaked lime powder is convenient for spraying into the vaporization cooling flue, increasing the heat contact area, preventing the problem of inconsistent thermal decomposition inside and outside, and preventing the clogging of the vaporizing cooling flue; but the particle size of the lime powder or slaked lime powder It is also not easy to be too small, because the particle size is too small, on the one hand, it is not convenient for the separation of soot and flue gas, and on the other hand, it affects the quality of pressed pellets.

The carrier gas for the injection of lime powder or slaked lime powder is an inert gas or a conventional vaporizing agent. The inert gas is preferably nitrogen; the conventional vaporizing agent is preferably CO ₂ or water vapor. The flow rate of the carrier gas is 20-200 m ³ /kg lime powder or slaked lime powder, preferably 20-100 m ³ /kg lime powder or slaked lime powder. In this way, the carbon dioxide content in the high-temperature flue gas of the metallurgical furnace is 14-19%, which is neither high nor low for gas recovery. The nitrogen or carbon dioxide flow in the gas has little effect on the amount of non-combustible gas in the vaporization flue; moreover, the appropriate amount of carbon dioxide generated by the decomposition of lime powder or slaked lime powder can increase the concentration of carbon dioxide in the high-temperature flue gas of the metallurgical furnace. The easier it is to separate the carbon dioxide, thereby reducing the cost of gas recovery.

To sum up, the method for carbon fixation in the vaporization cooling flue of a metallurgical furnace provided by the present invention uses the vaporization cooling flue as a reactor, adds a simple lime powder or slaked lime powder injection system to the original gas purification and recovery system, and uses Pneumatic conveying technology realizes green and efficient recycling of metallurgical furnace flue gas heat and metallurgical furnace gas, and the separated flue dust can also be directly used for the preparation of steel-making pellets, which is a sustainable and economical method for the metallurgical furnace steel-making industry. Chemical production provides an effective way. Lime powder or slaked lime powder is used for carbon fixation, which has high carbon fixation efficiency, and can be directly sprayed into the vaporization cooling flue without clogging the vaporization cooling flue. Because it is directly in contact with high-temperature flue gas, the utilization rate of lime is high; On the one hand, the improvement method of the metallurgical furnace smelting system is simple, and the overall circuit of the metallurgical furnace smelting system does not need to be changed, so the practicability is strong.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced. Without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. a method for carbon fixation in the vaporization cooling flue of metallurgical furnace, it is characterized in that, on the vaporization cooling flue of metallurgical furnace, add injection system, comprise the steps: before metallurgical flue gas dedusting, metallurgical furnace smelting in metallurgical furnace When the furnace gas is recovered, the lime powder or slaked lime powder is injected into the vaporization cooling flue through the injection system; the lime powder or slaked lime powder utilizes the waste heat of the metallurgical furnace flue gas to supply energy to solidify carbon dioxide; the remaining lime powder Or slaked lime powder is mixed with the dust separated from the metallurgical furnace flue gas, and the metallurgical furnace flue gas after carbon fixation is recycled. 2 . The carbon-fixing method in the vaporization cooling flue of a metallurgical furnace according to claim 1 , wherein the lime powder or slaked lime powder is sprayed at 1-20 kg/t steel. 3 . 3. the method for carbon fixation in metallurgical furnace vaporization cooling flue according to claim 2, is characterized in that, unreacted lime powder or slaked lime powder and the soot separated from metallurgical furnace flue gas are used for the process of steelmaking pellets together. preparation. 4 . The method for carbon-fixing in the vaporization cooling flue of a metallurgical furnace according to claim 1 , wherein the particle size of the lime powder or slaked lime powder is less than 0.075 mm. 5 . 5 . The method for fixing carbon in the vaporization cooling flue of a metallurgical furnace according to claim 4 , wherein the particle size of the lime powder or slaked lime powder is 0.025-0.075 mm. 6 . 6 . The method for solidifying carbon in the vaporization cooling flue of a metallurgical furnace according to claim 1 , wherein the carrier gas injected by the lime powder or slaked lime powder is an inert gas or a conventional vaporizing agent. 7 . 7 . The method for solidifying carbon in the vaporization cooling flue of a metallurgical furnace according to claim 6 , wherein the inert gas is nitrogen; and the conventional vaporizing agent is CO ₂ or water vapor. 8 . 8 . The method for carbon fixation in the vaporization cooling flue of a metallurgical furnace according to claim 6 , wherein the flow rate of the carrier gas is 20-200 m ³ /kg lime powder or slaked lime powder. 9 . 9 . The method for solidifying carbon in the vaporization cooling flue of a metallurgical furnace according to claim 1 , wherein the injection system comprises an air injection pipe, a powder spray tank communicated with the air injection pipe, and a The spray gun in the vaporization cooling flue, the spray gun is communicated with the jet pipe; the powder spray tank is used for accommodating the lime powder or slaked lime powder, and the carrier gas is sprayed into the jet pipe and carries the The lime powder or slaked lime powder is sprayed into the vaporization cooling flue together through the spray gun. 10. The method for carbon fixation in the vaporization cooling flue of a metallurgical furnace according to claim 9, wherein the spray gun is arranged at the front end of the flue gas dust removal equipment, and the end of the conveying pipe after the vaporization cooling flue is sprayed and cooled down, The spray gun is perpendicular to the side wall of the vaporization cooling flue.

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