Slag splashing furnace protection method and device for spraying carbon dioxide on carbonaceous and magnesian materials in converter

Abstract

The invention belongs to the field of metallurgy, and particularly relates to a slag-splashing furnace protection method and device for spraying carbonaceous and magnesian materials into a converter through carbon dioxide, and the method comprises the steps that when slag-splashing furnace protection is started, CO2 is used as carrier gas, the magnesian material and the carbonaceous material are sprayed into the converter respectively, then the carbonaceous material is continuously sprayed into the converter until slag-splashing furnace protection is finished, and the slag-splashing furnace protection is completed; in the whole slag-splashing furnace protection process, the temperature of coal gas in the converter is always kept at 1050 DEG C or above, the coal gas is recycled in the whole slag-splashing furnace protection process, CO2 is used as carrier gas, and carbon powder or coal powder is continuously sprayed into the converter, so that the slag-splashing furnace protection effect is improved, and a large amount of high-quality coal gas CO is generated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metallurgy, and particularly relates to a method and device for slag splashing and protecting a converter by spraying carbon dioxide and magnesium materials. BACKGROUND

[0002] The converter slag splashing and protection usually uses nitrogen, and the protection material usually uses magnesium-carbon balls. The carbon powder in the magnesium-carbon balls reduces the iron and manganese oxides in the slag, reduces the iron and manganese oxide components in the slag, and increases the melting point of the slag. The magnesium oxide in the magnesium-carbon balls increases the melting point, viscosity and corrosion resistance of the slag. A large amount of N2 is blown into the converter to reduce the temperature in the converter, reduce the temperature of the slag, increase the viscosity, and strengthen the slag adhesion of the furnace wall. The currently added magnesium-carbon balls need to be crushed and diffused in the converter, and need time to react and melt with the slag. The solid carbon powder reacts with the iron and manganese oxides in the slag, and the magnesium material also reacts with the slag, which are all solid-liquid reactions. The concentrated addition of the magnesium-carbon balls in the molten pool causes local cooling, increases the viscosity of the slag, and slows down the diffusion speed. The reaction of the carbon powder with the iron and manganese oxides in the slag is very insufficient. Although nitrogen is blown in for stirring, the solid carbon and magnesium materials are not easy to diffuse, the slag modification is not uniform, it is difficult to achieve an ideal homogeneous phase state, the low-melting-point phase has poor corrosion resistance, and the overall slag splashing and protection effect is affected. The added magnesium-carbon balls have high cost, slow reaction speed, insufficient reaction, and poor protection effect. The CO and CO2 generated by the reaction of the carbon powder and the slag cannot be ignited and can only be diffused. The large amount of physical heat of the flue gas can only recover a small amount of steam through the gasification flue. This causes a huge waste of energy.

[0003] Patent No. CN1974793A discloses a method for using CO2 for slag splashing and protection of a converter. This method uses a high-position bin to add carbon-containing materials and slag-making materials to the converter at one time, and uses CO2 as the carrier gas. This method has the following problems: 1. The material needs time to be blown apart after being formed into a group, and is blown to the furnace wall before reacting with the slag to form a homogeneous phase, which affects the protection effect; 2. The CO2 does not have sufficient reaction time with the carbon-containing materials, and the amount of CO generated is very small, which has no direct recycling value, and requires separate equipment for recovery and separation, which is not economically reasonable.

[0004] The current carbon emission reduction pressure is very large, and the operation cost of CO2 storage technology is too high. The storage of CO2 is also a safety hazard. The industrial application of CO2 is generally recognized as the best solution to reduce carbon emissions, but it is often not reasonable in technology and not cost-effective in economy due to high energy consumption and cost. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a method and device for slag splashing and protection of a converter by spraying carbon dioxide and magnesium materials. CO2 is used as the carrier gas, and carbon powder or coal powder is continuously sprayed into the converter, thereby improving the slag splashing and protection effect, and generating a large amount of high-quality coal gas CO.

[0006] A method for protecting the converter by spraying carbonaceous and magnesia materials with CO2, comprising the following steps: When the slag splashing protection is started, the magnesia material and the carbonaceous material are sprayed into the converter using CO2 as the carrier gas, and then the carbonaceous material is continuously sprayed until the end of the slag splashing protection, and the gas temperature in the converter is maintained above 1050 DEG C throughout the slag splashing protection process, and the gas is recovered throughout the slag splashing protection process.

[0007] The magnesia material is magnesia powder or magnesite powder, and the carbonaceous material is carbon powder or coal powder.

[0008] A device for protecting the converter by spraying carbonaceous and magnesia materials with CO2, comprising a converter, a flue gas cooling system, a dust removal system, an air induction system, a gas composition analysis system and a gas tank connected in sequence, and a slag splashing protection lance, wherein the slag splashing protection lance is deep into the converter body; the air induction system comprises a stop valve, an air inlet pipe, an air inlet stop valve and an air induction fan, the dust removal system is connected to the air induction fan through a pipeline, a stop valve is arranged at the gas outlet of the dust removal system, an air inlet pipe is arranged between the stop valve and the air induction fan, and an air inlet stop valve is arranged on the air inlet pipe; a gas tank and a diffusion system are connected in parallel after the air induction fan; a diffusion system stop valve is arranged at the inlet of the diffusion system, a gas composition analysis system is arranged on the inlet pipeline of the gas tank, and a gas recovery stop valve is arranged on the pipeline between the gas tank inlet and the gas composition analysis system.

[0009] The converter is an oxygen top-blown steelmaking converter.

[0010] The slag splashing protection lance comprises a slag splashing protection main gas pipe and a powder conveying pipe, the powder conveying pipe is arranged on one side or around the slag splashing protection main gas pipe, a Laval nozzle is arranged at the bottom of the slag splashing protection main gas pipe, a mixed flow chamber is arranged at the outlet of the Laval nozzle, the bottom of the powder conveying pipe is connected to the mixed flow chamber, the slag splashing protection main gas pipe is connected to a CO2 gas source, and the powder conveying pipe is connected to a powder spraying system; a second layer pipe is arranged outside the slag splashing protection main gas pipe and the powder conveying pipe, a cooling water inlet channel is arranged between the pipe walls of the second layer pipe, and the second layer pipe is connected to a cooling water system; a third layer pipe is arranged outside the second layer pipe, a cooling water return channel is arranged between the outer wall of the second layer pipe and the inner wall of the third layer pipe, and the cooling water return channel is connected to a return pipeline and connected to the cooling water system.

[0011] The powder conveying pipe is one or more.

[0012] A gas collecting hood is arranged above the converter body, a CO2 soft sealing protection cover is sealingly connected to the outside of the gas collecting hood, the CO2 soft sealing protection cover is connected to a CO2 gas charging pipeline, the CO2 gas charging pipeline is connected to a charging system, a pressure sensor is arranged in the CO2 soft sealing protection cover, and the CO2 soft sealing protection cover is further connected to a lifting device.

[0013] A temperature sensor is arranged on a straight pipe section of the gasification cooling flue connected with the converter body and the flue gas cooling system.

[0014] Before and after the slag splashing, the stop valve is closed and the air inlet valve is opened.

[0015] The beneficial effects of the present application are: 1. The present application uses CO2 as a carrier gas, and continuously sprays carbon powder or coal powder. The temperature in the hearth is very high, and the sprayed CO2 or CO2 generated by the decomposition of magnesite reacts with the continuously sprayed carbon powder or coal powder to generate CO. Due to the good reaction kinetics of the sprayed coal powder and the slag, the iron and manganese oxides in the slag are significantly reduced, and the saturation of magnesium in the slag is reduced. In the case of reduced consumption of magnesia materials, the slag splashing effect is still good.

[0016] 2. By continuously spraying carbon powder or coal powder into the converter, part of the carbon powder will be adhered to the splashing slag droplets, and the liquid slag droplets will continue to react, reducing the content of iron and manganese oxides and the saturation of magnesium in the liquid slag, thereby increasing the viscosity of the splashing droplets and promoting the slag hanging on the wall, and the formed slag shell is also more resistant to erosion.

[0017] 3. By continuously spraying carbon powder or coal powder into the converter, the reaction of CO2 and carbon powder or coal powder will be very sufficient, producing high-concentration CO and low-concentration CO2, which can be directly recovered without separation. At the same time, the excess coal powder will be dry distilled into semi-coke and discharged with the furnace gas, which can be recovered in the dust collector and sent to sintering as raw material.

[0018] 4. The sprayed magnesium oxide powder or magnesite powder has good dispersity and can be uniformly mixed with the slag, has less segregation, good tempering effect on the slag, and is more resistant to erosion after the slag splashing. Magnesia materials are sprayed in the first half of the slag splashing, and only carbon materials are sprayed in the later period.

[0019] 5. The device of the present application significantly reduces the amount of air entering the gas system through the air inlet at the front end of the induced draft fan and the CO2 soft seal protection cover, significantly improves the quality and calorific value of the gas, and is of great significance for chemical applications.

[0020] 6. The present application uses the converter waste heat to produce carbon sinks and obtain high-quality coal gas, reduces the cost of the slag splashing material, shortens the slag splashing time, and improves the slag splashing effect. At the same time, the physical heat in the furnace and the chemical heat of the slag are used to produce coal gas, and CO2 is consumed. It is a win-win situation. A new way for the industrial utilization of CO2 has been found.

[0021] 7. By modifying the induced draft system, the nitrogen concentration in the gas is significantly reduced, the coal gas recovery time is increased, the coal gas recovery amount is increased, and the calorific value of the coal gas is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 This is a schematic diagram of the slag splashing protection device for the converter carbon dioxide injection carbonaceous and magnesian materials of the present invention. In the attached diagram: 1. Converter; 2. Slag splashing torch; 3. Temperature sensor; 4. Gas collection hood; 5. CO2 soft-seal protective cover; 6. Flue gas cooling system; 7. Dust removal system; 8. Shut-off valve; 9. Air inlet pipe; 10. Inlet shut-off valve; 11. Exhaust fan; 12. Venting system; 13. Venting system shut-off valve; 14. Gas composition analysis system; 15. Gas recovery shut-off valve; 16. Gas holder. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings.

[0024] like Figure 1 As shown, a method for slag splashing protection of a converter by injecting carbon dioxide and carbonaceous and magnesian materials includes the following steps: When slag splashing for furnace protection begins, CO2 is used as the carrier gas. Initially, magnesia powder or magnesite powder and carbon powder or coal powder are simultaneously injected into converter 1. The amount of magnesia powder or magnesite powder injected depends on the difference between the initial MgO concentration in the slag and the required MgO concentration in the final slag. The required amount of magnesia powder or magnesite powder is calculated based on the amount of slag. Magnesia powder or magnesite powder is injected in the first half of the injection process, while carbon powder or coal powder is continuously injected in the second half until the end of the slag splashing process. Some of the injected carbon powder or coal powder reacts with the slag, reducing iron and manganese oxides in the slag, and some reacts with the carrier gas CO2 to generate CO. A small amount will also adhere to the slag, increasing the erosion resistance of the furnace wall. During the slag splashing process, the furnace temperature remains above 1050°C. The slag splashing process recovers coal gas throughout, and the reaction between CO2 and carbon powder is quite intense, filling the furnace with CO. During the slag splashing process, the splashed slag droplets also react with the CO in the furnace, further reducing iron and manganese oxides in the slag, increasing the slag melting point, and improving the corrosion resistance of the furnace wall after slag splashing.

[0025] Because CO2 has a higher specific heat capacity than nitrogen, and the reaction between CO2 and carbon is endothermic, and the dry distillation of pulverized coal is also an endothermic process, the slag splashing time for this process is shorter than that for nitrogen-based slag splashing. The specific slag splashing time depends on the temperature and composition of the original slag.

[0026] The temperature of the converter after tapping is still above 1500℃, and the carbon powder or coal powder is sprayed into the converter 1 with CO2 as the carrier gas and with magnesium oxide powder or magnesite powder, the carbon powder or coal powder sprayed has good dispersity, and is easy to react with the iron oxide or manganese oxide in the slag, rapidly reducing the iron and manganese oxides in the slag and increasing the melting point of the slag; the magnesium and carbon material sprayed directly reacts with the slag, without the crushing and dispersing process of the magnesium-carbon ball, greatly shortening the reaction time, faster reaction speed, more uniform composition, and the slag splashed on the furnace wall is more resistant to erosion, and the furnace protection effect is better. The temperature in the hearth is very high, the CO2 sprayed or the CO2 generated by the decomposition of the magnesium material reacts with the continuously sprayed carbon powder or coal powder to generate CO, the furnace is filled with CO, and the splashed slag droplets also continue to react with the CO in the furnace, reducing the iron and manganese oxides in the droplets, and increasing the melting point of the droplets, and the splashed droplets on the furnace wall are more resistant to erosion. At the same time, the coal gasification and the reaction of the carbon powder and CO2 are endothermic reactions, which will accelerate the cooling of the furnace, and the splashed slag droplets will also bond part of the carbon powder, and continue to react with the liquid slag droplets, reducing the iron and manganese oxide content and the saturation of magnesium in the liquid slag, which will increase the viscosity of the splashed droplets, promote the slag hanging on the wall, and the formed slag shell is more resistant to erosion; the excess coal powder will be dry distilled into semi-coke and discharged with the furnace gas, which is recovered in the dust collector and sent to sintering as raw material. The semi-coke is a green sintering fuel without volatile matter. The slag bonding part of the excess carbon powder will improve the erosion resistance of the furnace wall. The continuous spraying of carbon powder or coal powder and the reaction of CO2 with carbon powder or coal powder will be very sufficient, and the CO2 concentration in the furnace gas will be very low, so that the coal gas can be directly recovered, and the CO2 used can be recovered in the plant or recovered by other enterprises, directly obtaining carbon sink benefits. It is equivalent to treating CO2 with industrial waste heat, realizing real carbon sink, and the coal gas is used for steel production, which has greater significance. The CO2 is used as the carrier gas for splashing slag and furnace protection, and there is no N2 residue in the flue gas treatment system, which can improve the recovery of the smelting coal gas and improve the quality of the coal gas.

[0027] A converter carbon dioxide spraying carbon and magnesium material splashing slag and furnace protection device, comprising a converter 1, a flue gas cooling system 6, a dust removal system 7, an air induction system, a coal gas composition analysis system 14 and a coal gas tank 16 connected in sequence, and further comprising a splashing slag and furnace protection lance 2 which is deeply inserted into the converter 1; the air induction system comprises a stop valve 8, an air inlet pipe 9, an air inlet stop valve 10 and an air induction fan 11, the dust removal system 7 is connected to the air induction fan 11 through a pipeline, a stop valve 8 is arranged at the coal gas outlet of the dust removal system 7, an air inlet pipe 9 is arranged between the stop valve 8 and the air induction fan 11, and an air inlet stop valve 10 is arranged on the air inlet pipe 9; the coal gas tank 16 and a dispersing system 12 are connected in parallel after the air induction fan 11; a dispersing system stop valve 13 is arranged at the inlet of the dispersing system 12, a coal gas composition analysis system 14 is arranged on the inlet pipeline of the coal gas tank 16, and a coal gas recovery stop valve 15 is arranged on the pipeline between the inlet of the coal gas tank 16 and the coal gas composition analysis system 14; the converter 1 is an oxygen top-blown steelmaking converter; In this embodiment, the splash shield spray gun 2 is a spray gun with powder spraying function using CO2 as carrier gas, the flue gas cooling system 6 is a gasification flue evaporative cooler and evaporative cooler, etc., which is the same as the traditional converter cooling system; the dust removal system 7 is an electric dust collector; the flue gas cooling system 6, the diffusion system 12, the coal gas composition analysis system 14, the coal gas tank 16, the diffusion system stop valve 13, and the coal gas recovery stop valve 15 are all equipment used in the original converter, which is no different from the equipment of the traditional process, and the improvement of this part is not involved in this technology. In this embodiment, in order to reduce the N2 component in the coal gas, increase the amount of coal gas recovery, improve the quality of the coal gas, and also prevent the dry distillation semi-coke from burning in the dust removal system 7, an air inlet pipe 9 is additionally provided between the dust removal system 7 and the induced draft fan 11, and an air inlet stop valve 10 is provided. During tapping and after the end of the splash shield, the air inlet stop valve 10 is opened, and the induced draft fan 11 sucks in air at low speed to avoid the front end flue gas cooling system 6 entering the air, which causes the carbon powder in the dust collector to burn.

[0028] In this embodiment, after the converter 1 finishes blowing oxygen, in order to prevent the induced draft system from sucking in a large amount of air and affecting the recovery of coal gas, the air inlet stop valve 10 is opened, and the stop valve 8 after the dust removal system 7 is closed; when starting the splash shield, the stop valve 8 after the dust removal system 7 is opened, and the air inlet stop valve 10 is closed, and the induced draft fan 11 enters the normal working state; according to the process requirements, appropriate carbon powder or coal powder and magnesia powder or magnesite powder are selected, the two kinds of powder are respectively fed into the mixer, the spraying amount and speed of the two kinds of powder are respectively controlled, the amount of the two kinds of powder entering the powder spraying system at different stages is adjusted, CO2 is used as carrier gas, and the splash shield spray gun 2 is used to spray the magnesia powder or magnesite powder first, leaving enough melting time, and then continuously spraying the carbon powder or coal powder to ensure that the temperature of the converter coal gas is above 1050℃, and to ensure that the volatile matter of the coal powder is cracked at a temperature of 1050℃ or above. When the temperature is lower than 1050℃, stop spraying coal to avoid incomplete cracking of volatile matter, which causes the rear pipeline to be blocked; the diffusion and recovery of coal gas depends on the coal gas composition analysis system 14. When the coal gas composition analysis system 14 detects that the coal gas enters the recoverable state, the coal gas recovery stop valve 15 is opened, the diffusion system stop valve 13 is closed, and the coal gas recovery state is entered; when the coal gas recovery condition is not met, the diffusion system stop valve 13 is opened, and the coal gas is diffused; after the end of the splash shield, the speed of the induced draft fan 11 is reduced, the air inlet stop valve 10 is opened, and the stop valve 8 after the dust removal system 7 is closed; Before and after the splash shield, the stop valve 8 is closed, and the air inlet stop valve 10 is opened. The induced draft fan 11 sucks in air and idles to avoid the pipeline and the dust removal system 7 sucking in air during the period when no coal gas is produced before and after the splash shield, to prevent air from entering the dry distillation coal powder in the combustion pipeline and the dust removal system 7, and to reduce the amount of nitrogen gas entering the pipeline and the dust removal system 7, which affects the quality and recovery amount of the recovered coal gas.

[0029] The slag splashing and protecting lance 2 comprises a slag splashing and protecting main gas pipe, and one or more powder conveying pipes arranged on one side or around the slag splashing and protecting main gas pipe, a Laval nozzle arranged at the bottom of the slag splashing and protecting main gas pipe, a mixing chamber arranged at the outlet of the Laval nozzle, and a bottom of the powder conveying pipe connected with the mixing chamber.

[0030] In order to improve the effect of slag splashing and protection, the Laval nozzle is designed with double angles, the nozzle and the axis of the lance are at different angles, the body angle is related to the furnace type, and the water model experiment is recommended to determine, the height of slag splashing is different during slag splashing, the two angles can splash the slag to different heights, the double-angle lance can increase the slag splashing coverage area, and the furnace protection effect is better.

[0031] The converter 1 is provided with a gas collecting hood 4, the outer side of the gas collecting hood 4 is sealingly connected with a CO2 soft sealing protection cover 5, the CO2 soft sealing protection cover 5 is connected with a CO2 gas charging pipeline, the CO2 gas charging pipeline is connected with a charging system, a pressure sensor is arranged in the CO2 soft sealing protection cover 5, and the CO2 soft sealing protection cover 5 is further connected with a lifting device.

[0032] In the embodiment, the gas collecting hood 4 is originally arranged on the converter, in order to reduce the air suction between the furnace mouth and the gas collecting hood 4, the CO2 soft sealing protection cover 5 is arranged outside the gas collecting hood 4, the CO2 soft sealing protection cover 5 is a larger protection cover covering the gas collecting hood 4, the diameter and height of the CO2 soft sealing protection cover 5 are greater than those of the gas collecting hood 4, a closed ring is arranged at the lower part of the CO2 soft sealing protection cover 5, the gap between the converter wall and the CO2 soft sealing protection cover 5 is reduced, the air inlet and outlet space is reduced, and the CO2 overflow is reduced. During the slag splashing, when the gas collecting hood 4 is lowered, the CO2 soft sealing protection hood 5 is also lowered and CO2 gas is injected into the CO2 soft sealing protection hood 5, so that the CO2 soft sealing protection hood 5 is kept in a slightly positive pressure state, avoiding air entering the CO2 soft sealing protection hood 5. A pressure sensor is arranged in the CO2 soft sealing protection hood 5, and the pressure in the CO2 soft sealing protection hood 5 is kept 10-50 Pa higher than the external environment pressure. When the gas collecting hood 4 occasionally produces negative pressure, CO2 gas in the CO2 soft sealing protection hood 5 is sucked in, avoiding air being sucked into the gas collecting hood 4. The sucked CO2 reacts with excess carbon powder in the slag splashing flue gas to produce CO, avoiding N2 in the coal gas and increasing the amount of CO in the coal gas. Not only the amount of recovered coal gas is increased, but also the quality of the coal gas is improved. The technology is also applicable to the smelting period.

[0033] The pressure sensor arranged in the CO2 soft sealing protection hood 5 needs to be sensitive, avoiding air entering the protection hood and avoiding too much CO2 overflow. The pressure sensor is connected with the gas injection system, and the amount of injected CO2 is adjusted at any time.

[0034] The temperature sensor 3 is arranged in the straight pipe section of the gasification cooling flue connected with the converter 1 body and the flue gas cooling system 6, and is arranged on the gasification flue at the upper limit position of the CO2 soft sealing protection hood 5, for detecting the temperature of the furnace gas, and is connected with the powder injection system, for controlling the amount of injected carbon powder or coal powder.

[0035] The method and device of the application not only reduce the cost of the slag splashing material, but also shorten the slag splashing time and improve the slag splashing effect. At the same time, the physical heat and chemical heat of the furnace and the slag are used to produce coal gas and consume CO2. It is a win-win situation. A new way for industrial utilization of CO2 is found.

[0036] Example 1

[0037] A steel plant has two 120-ton oxygen top-blown converters. Since the company implements steel production and co-production, the demand for coal gas is large, and the converter has adopted the in-furnace coal injection process. In order to obtain more coal gas, the slag splashing method of the application is used in No. 2 converter, CO2 recovered from a lime kiln is used as the slag splashing carrier gas, magnesite powder is selected as the carbonaceous material, and anthracite powder used for blast furnace injection is selected as the carbonaceous material.

[0038] After tapping, pour out part of the slag, control the amount of slag at about 12 tons, the MgO content in the slag is about 4%, the original 2.0 tons of magnesium-carbon balls are added per furnace, the MgO content is about 55%, the carbon powder content is about 22%, the MgO content in the slag after splashing is about 12%, the spraying time is about 4 minutes, and the N2 consumption is about 1440 Nm3. The process uses CO2 as a carrier gas for spraying, and sprays magnesite powder and blast furnace injection coal. Each time 1.7 tons of magnesite powder containing 90% magnesium carbonate and 1.3 tons of coal powder are sprayed. The spraying time is shortened to 3 minutes, the CO2 consumption is about 1100 Nm3, and the heat value of the recovered coal gas is about 7000 kJ / Nm3.

[0039] The cost of blast furnace coal injection is 850 yuan / ton, and the cost is 1105 yuan. If the coal gas with a heat value of 7600 kJ / Nm3 is produced by the chemical industry, the cost is higher than 2 yuan / Nm3. If calculated at 2 yuan / Nm3, only the coal gas for slag splashing and furnace protection can create a profit of about 3800 yuan, create a carbon sink of about 2.5 tons, and equivalent to reducing 20 kg of CO2 per ton of steel. Compared with magnesium-carbon balls, each furnace saves about 1000 yuan. Compared with the unmodified converter, the FeO content in the slag after splashing is reduced by 5%, and the MgO content is about 8%, which is significantly better than the unmodified converter.

[0040] The air inlet pipe 9 in front of the air inlet pipe 9 is protected by the CO2 soft sealing protective cover 5 and the induced draft fan 11, and the air entering the gas is significantly reduced, and the N2 content in the gas is less than 3%, which is of great significance for chemical applications.

[0041] Example 2

[0042] A steel plant has two 100-ton oxygen top-blown converters. Due to the implementation of steel production and co-production by the company, the supply of coal gas is insufficient, and the N2 proportion in the coal gas is too high, which affects the use of the rear chemical industry. The two converters have adopted the in-furnace coal injection process. In order to obtain more coal gas, the No. 1 furnace adopts the slag splashing and furnace protection method of the present application, uses CO2 recovered by the chemical industry as the slag splashing and furnace protection carrier gas, and selects magnesite powder as the magnesia material. In order to facilitate, the carbonaceous material is selected as the anthracite powder produced by the blast furnace injection coal.

[0043] After tapping, pour out part of the slag, and control the amount of slag left at about 11 tons, the MgO content in the slag is about 5%, originally add about 1.8 tons of magnesium carbon balls per furnace, the MgO content is about 50%, the carbon powder content is about 25%, after splashing, the MgO content in the slag is about 14%, the spraying time is about 4.5 minutes, and the N2 consumption is about 1200 Nm3. This process uses CO2 as a carrier gas for spraying, and sprays magnesite powder and blast furnace injection coal, sprays 1.2 tons of magnesite powder containing 90% magnesium carbonate and 1.1 tons of coal powder each time. The spraying time is shortened to 3.5 minutes, the CO2 consumption is about 1000 Nm3, and the heat value of the recovered coal gas is about 7200 kJ / Nm3.

[0044] The cost of blast furnace injection coal is 860 yuan / ton, and the cost is 946 yuan. If the coal gas with a heat value of 7200 kJ / Nm3 is produced by the chemical industry, the cost is higher than 2 yuan / Nm3. If calculated at 2 yuan / Nm3, only the coal gas for each slag splashing and furnace protection can create a profit of about 3000 yuan, create a carbon sink of about 2.2 tons, equivalent to reducing 22 kg of CO2 per ton of steel. Compared with magnesium carbon balls, it saves about 1000 yuan per furnace. Compared with the unmodified converter, the FeO content in the slag after splashing is reduced by 6%, and the MgO content is about 8%, which is significantly better than the unmodified converter in furnace protection effect.

[0045] Through the protection of CO2 soft seal protection cover 5 and the air inlet pipe 9 set in front of the induced draft fan 11, the air entering the gas is significantly reduced, and the N2 content in the gas is less than 4%, which is of great significance for chemical links.

[0046] Through the transformation of the induced draft system, the nitrogen concentration in the gas is significantly reduced, and the coal gas recovery time and amount are also increased.

Claims

1. A method for protecting a converter from carbon dioxide injection of carbonaceous and magnesia materials by splashing slag, characterized in that, It comprises the following steps: In the beginning of the slag splashing protection, the magnesium material and the carbon material are sprayed into the converter by using CO2 as the carrier gas, then the carbon material is continuously sprayed until the end of the slag splashing protection, the temperature of the gas in the converter is kept above 1050℃ during the whole process of the slag splashing protection, and the gas is recycled during the whole process of the slag splashing protection.

2. A method of protecting the lining of a converter from carbon dioxide injection of carbonaceous and magnesia materials according to claim 1, characterised in that, The magnesium material is magnesium oxide powder or magnesite powder, and the carbon material is carbon powder or coal powder.

3. A converter carbon dioxide spray carbonaceous and magnesia material splashing and protecting furnace device applied to the converter carbon dioxide spray carbonaceous and magnesia material splashing and protecting furnace method of claim 1, characterized in that, The system comprises a converter, a flue gas cooling system, a dust removal system, an air induction system, a gas composition analysis system and a gas tank connected in sequence, and a slag splashing protection lance, wherein the slag splashing protection lance is deep into the converter body; the air induction system comprises a stop valve, an air inlet pipe, an inlet stop valve and an air induction fan, the dust removal system is connected to the air induction fan through a pipeline, a stop valve is arranged at the gas outlet of the dust removal system, an air inlet pipe is arranged between the stop valve and the air induction fan, and an inlet stop valve is arranged on the air inlet pipe; a gas tank and a diffusion system are connected in parallel after the air induction fan; a diffusion system stop valve is arranged at the inlet of the diffusion system, a gas composition analysis system is arranged on the inlet pipeline of the gas tank, and a gas recovery stop valve is arranged on the pipeline between the gas tank inlet and the gas composition analysis system.

4. The apparatus according to claim 3, wherein Before and after the slag splashing protection, the stop valve is closed and the inlet stop valve is opened.

5. The apparatus according to claim 3, wherein The converter is an oxygen top-blown steelmaking converter.

6. The apparatus according to claim 3, wherein The slag splashing protection lance comprises a slag splashing protection main gas pipe and a powder conveying pipe, the powder conveying pipe is arranged on one side or around the slag splashing protection main gas pipe, a Laval nozzle is arranged at the bottom of the slag splashing protection main gas pipe, a mixed flow chamber is arranged at the outlet of the Laval nozzle, the bottom of the powder conveying pipe is connected to the mixed flow chamber, the slag splashing protection main gas pipe is connected to a CO2 gas source, and the powder conveying pipe is connected to a powder spraying system; a second layer pipe is arranged outside the slag splashing protection main gas pipe and the powder conveying pipe, a cooling water inlet channel is arranged between the walls of the second layer pipe, and the second layer pipe is connected to a cooling water system; a third layer pipe is arranged outside the second layer pipe, a cooling water return channel is arranged between the outer wall of the second layer pipe and the inner wall of the third layer pipe, and the cooling water return channel is connected to a return pipeline and connected to the cooling water system.

7. The apparatus according to claim 5, wherein the carbon dioxide lance is arranged to direct the carbon dioxide jet at an angle of 30 to 60 degrees to the horizontal. The powder conveying pipe is one or more.

8. The apparatus according to claim 3, wherein A gas collecting hood is arranged above the converter body, a CO2 soft sealing protection cover is sealingly connected to the outside of the gas collecting hood, the CO2 soft sealing protection cover is connected to a CO2 gas charging pipeline, the CO2 gas charging pipeline is connected to a charging system, a pressure sensor is arranged in the CO2 soft sealing protection cover, and the CO2 soft sealing protection cover is further connected to a lifting device.

9. The apparatus according to claim 3, wherein A temperature sensor is arranged on the straight pipe section of the gasification cooling flue connected between the converter body and the flue gas cooling system.

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