CN212713623U - Self-generating coal gas circulation non-tail gas emission smelting steel scrap system - Google Patents
Self-generating coal gas circulation non-tail gas emission smelting steel scrap system Download PDFInfo
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Abstract
A self-generating coal gas circulation non-tail gas emission smelting steel scrap system belongs to the technical field of metallurgy and comprises a system bag feeding system, a furnace body, a dust remover, a variable-frequency draught fan, a coal gas cabinet, a chimney, a coal gasification furnace, a cyclone dust remover, a liftable heat preservation cover, a storage bin, a fine adjustment tundish and a steel ladle. The system of the utility model utilizes the high-temperature flue gas coal injection of the shaft furnace to generate coal gas, realizes the full waste steel smelting of the self-circulation of the fuel gas, can realize the zero emission of the flue gas in the smelting link, and achieves the effect of the reasonable cyclic utilization of energy source flow; meanwhile, the energy flow is more reasonable, the heat consumption in the coal gas generation process is reduced, and the waste water treatment equipment and the cost in the coal gas generation process are avoided; the energy saving and emission reduction effects are remarkable, the energy consumption in the smelting link is only about 25% of that of the traditional electric arc furnace, and the whole manufacturing cost is reduced by 180-260 yuan per ton of steel compared with that of the electric arc furnace; the utility model discloses a full steel scrap smelting system is energy-conserving, low carbon, environmental protection, low cost in the green system of smelting of an organic whole.
Description
Technical Field
The utility model belongs to the technical field of the metallurgy, in particular to from generating gas circulation no exhaust emissions smelting steel scrap system.
Background
At present, two main methods for steel smelting are available: one is a long process, which comprises the working procedures of mining, ore dressing, sintering, blast furnace ironmaking, converter steelmaking, refining, continuous casting and the like; the other is a short process, which comprises the procedures of melting, refining, continuous casting and the like in an electric arc furnace or an intermediate frequency furnace. Influenced by the factors of increasing discharge pressure and steel scrap resources, the short process is favored by the industry.
The electric power structure of China is mainly thermal power generation, the thermal power generation is a process of converting thermal energy into electric energy, the highest conversion rate of the process is about 40%, it can be seen that about 60% of energy is wasted in the conversion process, the power generation operation process can generate considerable operation cost, the transmission cost and the loss of electricity are generated from electricity transmission to electricity utilization customers, the electric heat conversion process of the users can also have electric energy loss, an electric arc furnace can also have consumption of electrodes during smelting, and the production process of the electrodes is a high-energy-consumption and high-pollution process. It can be seen that the electric arc furnace smelting process has the problems of high energy consumption, high cost and low conversion rate from the viewpoint of energy flow and energy utilization rate.
At present, a gas producer has many problems, because of the structure of the gas producer, the top coal is gradually heated in the process of generating gas, the coal is subjected to low-temperature dry distillation to generate a large amount of long-chain organic matters, benzene, naphthalene and tar substances, generated gas must be washed to remove the substances and remove dust, a large amount of waste water is generated, and the environmental pollution is serious, so that the government strictly limits the process and restricts the development of a plurality of enterprises using gas. The process has the advantages of large heat loss, complex control, low calorific value of generated fuel gas and great reduction of the use of the fuel gas.
In addition, anthracite is used as a sintering process fuel in most iron and steel enterprises in China, the roasting process of the sintering process is progressive heating, volatile matters in coal are distilled and volatilized to escape without reaching a burning point, and volatile matters escape without burning at all, so that huge waste of a calorific value is caused, and meanwhile, the volatile matters discharged into the atmosphere are changed into VOC (volatile organic compounds), pollute the atmosphere, and are the largest emission source of industrial VOC at present. The volume of the resident bulk coal combustion furnace is very small, the furnace temperature is rapidly reduced in the process of adding coal, the newly added coal is subjected to low-temperature dry distillation, and the volatile components distilled by drying escape without being combusted, so that the calorific value is lost, and VOC escape is also caused, which is the largest pollution caused by bulk coal combustion.
The problems are social problems which need to be solved urgently, and in order to solve the problems, a self-generated coal gas circulation non-tail gas emission smelting steel waste system is developed.
SUMMERY OF THE UTILITY MODEL
For making full scrap iron and steel smelt lower carbon green more, solve above-mentioned social problem simultaneously, the utility model provides a do not have tail gas discharge from generating gas circulation and smelt steel scrap system utilizes shaft furnace self high temperature flue gas dry distillation coal, takes place gasification reaction with the carbon dioxide in the flue gas and partial coal simultaneously, and iron ore sintering fuel or making the moulded coal are done to surplus carbon powder, and high temperature flue gas is high calorific value gas, and high temperature gas is through cooling with the steel scrap heat transfer, then gets into the gas chamber after the dust remover removes dust and retrieves reserve. The generated gas quantity is larger than the requirement of the steel furnace, so the coal gas can be used for other gas-using equipment such as steel rolling and the like, and a gas generating facility does not need to be additionally built. The method realizes the full waste steel smelting of gas self-circulation, can realize zero emission of smoke in the smelting link, and achieves the effect of reasonable recycling of energy source flow, and the specific technical scheme is as follows:
a self-generating coal gas circulation non-tail gas emission smelting steel scrap system comprises a feeding system 1, a shaft furnace 2, a dust remover 3, a variable frequency induced draft fan 4, a coal gas cabinet 5, a chimney 6, a coal gasification furnace 7, a cyclone dust remover 8, a liftable heat preservation cover 9, a stock bin 10, a fine adjustment tundish 11 and a steel ladle 12;
a steel tapping hole 13 is formed in the side wall of the bottom of the shaft furnace 2, a molten steel heating oxygen combustion burner 14 is arranged at the lower part of a melting section of the shaft furnace 2, a main oxygen burner 15 is arranged at the upper part of the melting section of the shaft furnace 2, an annular flue 16 is arranged at the 1200-1700 ℃ temperature position of a transition section of the shaft furnace 2, a cooling spray system 17 is arranged at a preheating section of the shaft furnace 2, and a sealed charging system 18 is arranged at the top of the shaft furnace 2;
the coal gasification furnace 7 is provided with a coal injection gun 20, an oxygen nozzle 21 and a steam injection device 22;
the lifting heat-preserving cover 9 is provided with a temperature-measuring sampling port 24 and an oxygen combustion gun 25;
a steel flowing port 26 is formed in the lower portion of the side wall of the fine adjustment tundish 11, and a bottom blowing air brick 27 is arranged at the bottom of the fine adjustment tundish 11;
the feeding end of the feeding system 1 is connected with a sealed feeding system 18 at the top of the shaft furnace 2, a smoke outlet at the upper part of the shaft furnace 2 is connected with an air inlet of a dust remover 3 through a pipeline, an air outlet of the dust remover 3 is connected with an induced draft port of a variable frequency induced draft fan 4 through a pipeline, an air inlet pipe 19 is arranged on a connecting pipeline of the dust remover 3 and the variable frequency induced draft fan 4, and an air outlet of the variable frequency induced draft fan 4 is respectively connected with a gas tank 5 and a chimney 6 through pipelines;
the lower flue of the annular flue 16 is sequentially connected with a coal gasification furnace 7 and a cyclone dust collector 8 through pipelines, and the cyclone dust collector 8 is connected with the upper flue of the annular flue 16 through a return flue gas pipeline;
a steel tapping hole 13 of the shaft furnace 2 is connected with a fine adjustment tundish 11 through a pipeline, a liftable heat preservation cover 9 is covered on the fine adjustment tundish 11, an auxiliary material feeding hole on the liftable heat preservation cover 9 is connected with a bottom discharge hole of the storage bin 10 through a pipeline, and a smoke return hole on the liftable heat preservation cover 9 is connected with an annular flue 16 through a smoke return pipeline 23;
a steel ladle 12 is arranged below a steel flowing port 26 of the fine adjustment tundish 11 and is used for receiving molten steel;
a gas control valve is arranged at a gas outlet of the dust remover 3, a gas control valve is arranged at the gas inlet pipe 19, a gas control valve is arranged on a connecting pipeline of the variable-frequency draught fan 4 and the gas tank 5, and a gas control valve is arranged on a connecting pipeline of the variable-frequency draught fan 4 and the chimney 6;
a smoke outlet of the lower flue of the annular flue 16 is provided with a gas control valve, and a smoke inlet of the upper flue of the annular flue 16 is provided with a gas control valve;
a steel tapping hole 13 of the shaft furnace 2 is provided with a plugging stopper rod;
a stopper rod is arranged outside the steel flowing port 26 of the fine adjustment tundish 11;
the tail end of the cooling spraying system 17 is communicated with a water source;
a steel runner is arranged in a smelting area of the shaft furnace 2 and is covered with a refractory cover plate;
a dry distillation coal collecting bin, a carbon powder cooling and recovering device and a temperature sensor are also arranged in the coal gasification furnace 7;
the quantity of the molten steel heating oxygen combustion burner 14 and the quantity of the main oxygen combustion burner 15 are determined according to the equipment scale of the shaft furnace 2; the number of the coal injection guns 20, the number of the oxygen nozzles 21 and the number of the steam injection devices 22 are determined according to the equipment scale of the coal gasification furnace 7;
the molten steel heating oxygen-combustion burner 14 is replaced by an oxygen-combustion gun; the primary oxygen burner 15 is replaced by an oxygen burner;
the fine tuning tundish 11 can be replaced by a ladle 12;
the steelmaking method of the self-generating coal gas circulation non-tail gas emission smelting steel scrap system comprises the following steps:
step 1, feeding:
when a new furnace is opened, arranging furnace burden in the center area of the bottom of the shaft furnace 2, paving two layers of oil-immersed sleepers, arranging coke on the sleepers, arranging scrap steel with a certain length in the center area of the coke, reserving a combustion reaction area for flame sprayed by a molten steel heating oxygen combustion burner 14 and a main oxygen burner 15, arranging light steel materials or broken steel materials on the upper part of the scrap steel, melting low-melting-point substances such as iron oxide on the surface of the scrap steel during normal smelting, bonding the light steel materials or the broken steel materials together to form a steel material column, preventing the steel material column from scattering in a combustion reserved space or falling in a runner in the shaft furnace 2, covering a refractory cover plate on the runner to prevent the unmelted scrap steel from scattering in the runner to reduce the temperature of the molten steel, and enabling the molten steel to flow down and preventing the unmelted steel from leaking;
step 2, coal gas generation:
spraying the ground low-sulfur coal powder with the grain diameter less than 3mm into coal by using a coal spraying gun 20High-temperature flue gas generated by smelting in the coal gasifier 7 enters the coal gasifier 7 through a lower flue of the annular flue 16, and low-sulfur coal powder is subjected to dry distillation; the coal gas which is dry distilled under the high temperature environment of more than 1100 ℃ can be cracked, long-chain hydrocarbon is cracked into low liquefaction point fuel gas such as short-chain alkane, hydrocarbon, hydrogen and the like, and CO in the high temperature flue gas2And residual O2And the steam injected by the steam injection device 22 can chemically react with the volatile matters and the newly generated dry distillation carbon to generate composite coal gas, and the heat value of the composite coal gas is controlled to be 1500-2500 Kcal/m3(ii) a When the internal temperature of the coal gasification furnace 7 is lower than 1100 ℃, a proper amount of oxygen is additionally blown through the oxygen nozzle 21 to heat the coal gasification furnace 7 and keep the temperature above 1100 ℃, and the gasification temperature is preferably 1400-1700 ℃;
step 3, gas circulation and preheating:
the temperature of the composite coal gas generated after the coal gas is over 900 ℃, the dry distillation coal and the smoke dust generated by the coal gasification furnace 7 are recovered by the cyclone dust collector 8, the composite coal gas is cleaned by the cyclone dust collector 8 and then enters the upper flue of the annular flue 16 through the return flue gas pipeline, and then is led back into the shaft furnace 2, and the preheating of the scrap steel by the composite coal gas is completed; the dry distillation coal which is not gasified by dry distillation falls into a dry distillation coal collecting bin inside the coal gasification furnace 7, is cooled and collected by waste heat recovery, and is sent to the iron making furnace together with the dust removal ash to be sintered as fuel;
starting the variable-frequency draught fan 4 for cold running, starting the molten steel heating oxygen combustion burner 14 and the main oxygen burner 15 after the variable-frequency draught fan 4 works normally, controlling the peroxide coefficients of the molten steel heating oxygen combustion burner 14 and the main oxygen burner 15 to be 1.5-3.0, then heating the furnace bottom by burning coke, opening the plugging stopper of the steel outlet 13 when the molten steel reaches the tapping temperature, and continuously tapping;
when entering a normal smelting stage, the peroxide coefficients of the molten steel heating oxygen combustion burner 14 and the main oxygen combustion burner 15 are adjusted to be below 1.0, so that unburned coal gas and ferric oxide on the surface of the scrap steel are subjected to indirect reduction reaction, and the oxidation of the scrap steel is avoided;
opening a plugging stopper of the steel outlet 13 to enable molten steel to flow into the fine adjustment tundish 11, and starting the oxygen combustion gun 25 to heat the molten steel in the fine adjustment tundish 11 to more than 1550 ℃, preferably more than 1600 ℃; before tapping, according to the requirements of molten steel components, deoxidizing agents, alloys and slagging auxiliary materials in a storage bin 10 are added into a fine adjustment tundish 11, and fine adjustment of alloying components, recarburization and diffusion deoxidation are carried out on the molten steel;
when the components of the molten steel are fine-adjusted, the bottom blowing air brick 27 blows argon gas and is stirred, so that the temperature and the components of the molten steel are uniform, the alloy yield is high due to diffusion deoxidation, and less aluminum deoxidizers can be added, so that the molten steel has few inclusions;
during the tapping process and the fine adjustment of components, the oxygen combustion gun 25 is always in a working state, the air supply intensity can be adjusted according to heating requirements, the oxygen combustion ratio is controlled to be 1-1.01, a valve of the smoke return pipeline 23 is controlled by a pressure sensor in the fine adjustment tundish 11, the micro negative pressure is kept to be-20-30 Pa all the time, and not only is the situation that smoke cannot overflow out ensured, but also too much air cannot be sucked in; all the burnt high-temperature flue gas enters the coal gasification furnace 7 through the smoke return pipeline 23, and the high-temperature flue gas carries out dry distillation on low-sulfur coal powder to generate composite coal gas;
when the molten steel in the fine adjustment tundish 11 is enough for one pot of molten steel, a stopper rod at a steel outlet of the fine adjustment tundish 11 is opened, the molten steel flows into a ladle 12, the ladle 12 is transferred to an LF furnace station for refining, and final fine adjustment and waiting are carried out;
when the fine adjustment tundish 11 is replaced, the steel tapping hole 13 is plugged by a stopper rod to stop tapping, all molten steel in the fine adjustment tundish 11 is drained, then the fine adjustment tundish 11 is moved out and replaced, and the operation is reset to continue tapping continuously.
The utility model discloses a from no exhaust emissions of spontaneous coal gas circulation system of smelting steel scrap, compared with prior art, beneficial effect is:
firstly, high-temperature flue gas generated by smelting in the shaft furnace of the utility model enters the coal gasification furnace through the lower flue of the annular flue at the transition section of the shaft furnace; high-temperature flue gas generated by heating the oxygen combustion gun during fine adjustment enters the coal gasification furnace through the smoke return pipeline; the high-temperature flue gas from the two channels carries out high-temperature dry distillation on the low-sulfur coal powder in the coal gasification furnace, so that the low-sulfur coal powder is subjected to dry distillation, cracking and gasification, and is reacted and gasified in carbon dioxide to prepare composite coal gas, high-temperature waste heat is efficiently recycled, low-efficiency conversion of the waste heat is avoided, the flue gas containing the carbon dioxide is also utilized, no water consumption and no waste water are generated, the investment is small, the operation cost is low, and the process is a real green coal gas generation process.
And secondly, because the smoke is not discharged outside, dioxin can be combusted during combustion, heavy metals can be diluted and adsorbed by molten steel during circulating combustion, sulfur can circulate in the system, low-sulfur coal is selected, the smoke can enter a gas chamber without desulfurization within the molten steel bearing range, dust can be directly removed, the temperature of the smoke at the top of the furnace after heat exchange with waste steel is reduced to about 100 ℃, and the smoke enters the gas chamber after dust removal, so that no smoke is discharged in a smelting link, and atmospheric pollution is avoided.
Thirdly, the heating value of the composite gas generated by the steelmaking system can be controlled at 1500-2500 Kcal/m3The method can be used for melting scrap steel by heating in a shaft furnace, and can also be used for a steel rolling heating furnace or other purposes; the temperature of the coal gas of the coal-out gasification furnace can still reach 900-1050 ℃; the coal gas is led back to the shaft furnace to preheat the scrap steel, because the upper part of the shaft furnace is in reducing atmosphere, oxidation burning loss is avoided, iron oxide on the surface of the scrap steel can be reduced, and valuable metal zinc can be effectively recovered.
And fourthly, because the upper part of the shaft furnace has coal gas, the oxygen-fuel ratio of an oxygen-fuel burner or an oxygen-fuel gun can be less than 1, the oxidation of the lower part of the scrap steel can be greatly reduced, the upper part of the shaft furnace is in reducing atmosphere, and iron oxide scales on the surface of the scrap steel can be reduced, so that the metal yield can be greatly improved, the oxygen content of the molten steel can be greatly reduced, the molten steel at the rear part can be deoxidized without aluminum, the cost of the deoxidizer can be reduced, the aluminum oxide inclusion of the molten steel can be avoided, the process pressure of rear part refining is greatly reduced, and the refining cost.
Fifthly, due to oxy-fuel combustion, the amount of flue gas is small, the amount of heat taken away is small, no nitrogen participates in circulation, and the generated gas has high heat value; the coal is pyrolyzed by utilizing the high-temperature characteristic of the flue gas, high-liquefaction point substances in the coal gas are removed, the subsequent coal gas treatment is facilitated, the storage and the conveying of the coal gas are also facilitated, the carbon dioxide in the flue gas reacts with the pyrolyzed coal to generate fuel gas, and no carbon dioxide is discharged in the smelting link.
In summary, the utility model utilizes the temperature distribution characteristic of the shaft furnace to generate gas, thereby not only avoiding reconstruction of gas generating equipment, but also making the energy flow more reasonable, reducing the heat consumption in the gas generating process and avoiding the waste water treatment equipment and cost in the gas generating process; the energy saving and emission reduction effects are remarkable, the energy consumption in the smelting link is only about 25% of that of the traditional electric arc furnace, and the whole manufacturing cost is reduced by 180-260 yuan per ton of steel compared with that of the electric arc furnace; the utility model discloses a full steel scrap smelting system is energy-conserving, low carbon, environmental protection, low cost in the green system of smelting of an organic whole.
Drawings
FIG. 1 is the structure schematic diagram of the self-generating gas circulation non-exhaust emission smelting steel scrap system: in the figure, 1-a feeding system, 2-a shaft furnace, 3-a dust remover, 4-a variable frequency draught fan, 5-a gas cabinet, 6-a chimney, 7-a coal gasification furnace, 8-a cyclone dust remover, 9-a liftable heat preservation cover, 10-a storage bin, 11-a fine adjustment tundish, 12-a steel ladle, 13-a steel outlet, 14-a molten steel heating oxygen combustion burner, 15-a main oxygen combustion nozzle, 16-an annular flue, 17-a cooling spray system, 18-a sealed feeding system, 19-an air inlet pipe, 20-a coal injection gun, 21-an oxygen nozzle, 22-a steam injection device, 23-a smoke return pipeline, 24-a temperature measurement sampling port, 25-an oxygen combustion gun, 26-a steel flowing port and 27-a bottom blowing air brick.
Detailed Description
The present invention will be further described with reference to the following detailed description and the accompanying fig. 1, but the present invention is not limited to these embodiments.
Example 1
As shown in fig. 1, a self-generating gas circulation non-exhaust emission smelting steel scrap system comprises a feeding system 1, a shaft furnace 2, a dust remover 3, a variable frequency draught fan 4, a gas cabinet 5, a chimney 6, a coal gasification furnace 7, a cyclone dust remover 8, a liftable heat preservation cover 9, a storage bin 10, a fine adjustment tundish 11 and a steel ladle 12;
a steel tapping hole 13 is formed in the side wall of the bottom of the shaft furnace 2, a molten steel heating oxygen combustion burner 14 is arranged at the lower part of a melting section of the shaft furnace 2, a main oxygen burner 15 is arranged at the upper part of the melting section of the shaft furnace 2, an annular flue 16 is arranged at the 1200-1700 ℃ temperature position of a transition section of the shaft furnace 2, a cooling spray system 17 is arranged at a preheating section of the shaft furnace 2, and a sealed charging system 18 is arranged at the top of the shaft furnace 2;
the coal gasification furnace 7 is provided with a coal injection gun 20, an oxygen nozzle 21 and a steam injection device 22;
the lifting heat-preserving cover 9 is provided with a temperature-measuring sampling port 24 and an oxygen combustion gun 25;
a steel flowing port 26 is formed in the lower portion of the side wall of the fine adjustment tundish 11, and a bottom blowing air brick 27 is arranged at the bottom of the fine adjustment tundish 11;
the feeding end of the feeding system 1 is connected with a sealed feeding system 18 at the top of the shaft furnace 2, a smoke outlet at the upper part of the shaft furnace 2 is connected with an air inlet of a dust remover 3 through a pipeline, an air outlet of the dust remover 3 is connected with an induced draft port of a variable frequency induced draft fan 4 through a pipeline, an air inlet pipe 19 is arranged on a connecting pipeline of the dust remover 3 and the variable frequency induced draft fan 4, and an air outlet of the variable frequency induced draft fan 4 is respectively connected with a gas tank 5 and a chimney 6 through pipelines;
the lower flue of the annular flue 16 is sequentially connected with a coal gasification furnace 7 and a cyclone dust collector 8 through pipelines, and the cyclone dust collector 8 is connected with the upper flue of the annular flue 16 through a return flue gas pipeline;
a steel tapping hole 13 of the shaft furnace 2 is connected with a fine adjustment tundish 11 through a pipeline, a liftable heat preservation cover 9 is covered on the fine adjustment tundish 11, an auxiliary material feeding hole on the liftable heat preservation cover 9 is connected with a bottom discharge hole of the storage bin 10 through a pipeline, and a smoke return hole on the liftable heat preservation cover 9 is connected with an annular flue 16 through a smoke return pipeline 23;
a steel ladle 12 is arranged below a steel flowing port 26 of the fine adjustment tundish 11 and is used for receiving molten steel;
a gas control valve is arranged at a gas outlet of the dust remover 3, a gas control valve is arranged at the gas inlet pipe 19, a gas control valve is arranged on a connecting pipeline of the variable-frequency draught fan 4 and the gas tank 5, and a gas control valve is arranged on a connecting pipeline of the variable-frequency draught fan 4 and the chimney 6;
a smoke outlet of the lower flue of the annular flue 16 is provided with a gas control valve, and a smoke inlet of the upper flue of the annular flue 16 is provided with a gas control valve;
a steel tapping hole 13 of the shaft furnace 2 is provided with a plugging stopper rod;
a stopper rod is arranged outside the steel flowing port 26 of the fine adjustment tundish 11;
the tail end of the cooling spraying system 17 is communicated with a water source;
a steel runner is arranged in a smelting area of the shaft furnace 2 and is covered with a refractory cover plate;
a dry distillation coal collecting bin, a carbon powder recovery device and a temperature sensor are also arranged in the coal gasification furnace 7;
the quantity of the molten steel heating oxygen combustion burner 14 and the quantity of the main oxygen combustion burner 15 are determined according to the equipment scale of the shaft furnace 2; the number of the coal injection guns 20, the number of the oxygen nozzles 21 and the number of the steam injection devices 22 are determined according to the equipment scale of the coal gasification furnace 7;
the molten steel heating oxygen-combustion burner 14 is replaced by an oxygen-combustion gun; the primary oxygen burner 15 is replaced by an oxygen burner;
the fine tuning tundish 11 can be replaced by a ladle 12;
in the embodiment, a self-generated gas circulation non-tail gas emission smelting steel scrap system is newly built in a certain iron and steel enterprise, the inner diameter of an upper preheating zone of a shaft furnace 2 is 2.4 meters, the height of the upper preheating zone is 16 meters, the inner diameter of a lower combustion zone is 3.5 meters, the height of the combustion zone is 3 meters, the transition height from the combustion zone to an upper thin section is 3 meters, the total height of the shaft furnace 2 is 22 meters, a steel scrap supporting platform is arranged at the bottom, the diameter of the platform is 2.8 meters, a steel flowing channel is arranged at the periphery of the platform and is inclined, a steel tapping hole is lowest, the steel tapping hole is shallowest, the steel flowing channel at the shallowest position is 300mm deep, molten steel flows to the steel tapping hole through the steel flowing channel, and the molten steel flows out. In order to prevent the unmelted scrap steel from scattering into the runner, the runner is covered with refractory bricks and a runner seam is left. The 500mm position on the scrap steel supporting platform is provided with 6 main oxygen combustion nozzles 15 surrounding the shaft furnace 2, the periphery of the furnace is uniformly distributed, the muzzle is obliquely arranged downwards, the lower limit of flame is arranged to the center of the scrap steel supporting platform, the main oxygen combustion nozzles are mainly used for melting and preheating scrap steel and are the main energy supply of the shaft furnace 2.4 molten steel heating oxygen combustion burners 14 surrounding the shaft furnace 2 are arranged on the scrap steel support table at the position of 200mm, the molten steel heating oxygen combustion burners are arranged obliquely downwards along the tangent line, the flame points to the molten steel runner, the impact direction is consistent with the flow direction of the molten steel, the molten steel heating oxygen combustion burners 14 are mainly used for heating the molten steel after melting, and the molten steel heating oxygen combustion burners 14 can also be used for adjusting and improving the productivity. The steel flowing channel in the flame zone is not covered with refractory bricks, and a heating zone is reserved.
8 air inducing holes are arranged at the temperature of 1200-1400 ℃ in the transition section of the shaft furnace 2, a lower flue of the annular flue 16 is arranged outside the air inducing holes, 8 air inlet holes are arranged at the position 2 meters away from the upper part of the air inducing holes, and an upper flue of the annular flue 16 is arranged outside the air inlet.
A coal gasification furnace 7 is arranged beside the shaft furnace, and the coal gasification furnace 7 comprises a furnace body, an air inlet, an air outlet, 3 coal injection guns, 3 oxygen nozzles, a steam injection device, a dry distillation coal collection bin and a temperature sensor.
A steel-making method of a self-generating coal gas circulation non-tail gas emission smelting steel scrap system comprises the following steps:
step 1, feeding:
when a new furnace is opened, arranging furnace burden in the center area of the bottom of the shaft furnace 2, paving two layers of oil-immersed sleepers, arranging coke on the sleepers, arranging scrap steel with a certain length in the center area of the coke, reserving a combustion reaction area for flame sprayed by a molten steel heating oxygen combustion burner 14 and a main oxygen burner 15, arranging light steel materials or broken steel materials on the upper part of the scrap steel, melting low-melting-point substances such as iron oxide on the surface of the scrap steel during normal smelting, bonding the light steel materials or the broken steel materials together to form a steel material column, preventing the steel material column from scattering in a combustion reserved space or falling in a runner in the shaft furnace 2, covering a refractory cover plate on the runner to prevent the unmelted scrap steel from scattering in the runner to reduce the temperature of the molten steel, and enabling the molten steel to flow down and preventing the unmelted steel from leaking;
step 2, coal gas generation:
spraying the ground low-sulfur coal powder with the particle size less than 3mm into the coal gasification furnace 7 by using a coal spraying gun 20, feeding high-temperature flue gas generated by smelting in the furnace into the coal gasification furnace 7 through a lower flue of the annular flue 16, and discharging the low-sulfur coal powderDry distillation; the coal gas which is dry distilled under the high temperature environment of more than 1100 ℃ can be cracked, long-chain hydrocarbon is cracked into low liquefaction point fuel gas such as short-chain alkane, hydrocarbon, hydrogen and the like, and CO in the high temperature flue gas2And residual O2And the steam injected by the steam injection device 22 can chemically react with the volatile matters and the newly generated dry distillation carbon to generate composite coal gas, and the heat value of the composite coal gas is controlled to be 1500-2500 Kcal/m3(ii) a When the internal temperature of the coal gasification furnace 7 is lower than 1100 ℃, a proper amount of oxygen is additionally blown through the oxygen nozzle 21 to heat the coal gasification furnace 7 and keep the temperature above 1100 ℃, and the gasification temperature is preferably 1400-1700 ℃; the dry distillation coal which is not gasified by dry distillation falls into a dry distillation coal collecting bin inside the coal gasification furnace 7, is cooled and collected by waste heat recovery, and is sent to the iron making furnace together with the dust removal ash to be sintered as fuel;
step 3, gas circulation and preheating:
the temperature of the composite coal gas after the coal gas generation is still above 900 ℃, the dry distillation coal and the smoke dust generated by the coal gasification furnace 7 are recovered by the cyclone dust collector 8, the composite coal gas is cleaned by the cyclone dust collector 8 and then enters the upper flue of the annular flue 16 through the return flue gas pipeline, and then is led back into the shaft furnace 2, and the waste steel is preheated by the composite coal gas;
starting the variable-frequency draught fan 4 for cold running, starting the molten steel heating oxygen combustion burner 14 and the main oxygen burner 15 after the variable-frequency draught fan 4 works normally, controlling the peroxide coefficients of the molten steel heating oxygen combustion burner 14 and the main oxygen burner 15 to be 1.5-3.0, then heating the furnace bottom by burning coke, opening the plugging stopper of the steel outlet 13 when the molten steel reaches the tapping temperature, and continuously tapping;
when entering a normal smelting stage, the peroxide coefficients of the molten steel heating oxygen combustion burner 14 and the main oxygen combustion burner 15 are adjusted to be below 1.0, so that unburned coal gas and ferric oxide on the surface of the scrap steel are subjected to indirect reduction reaction, and the oxidation of the scrap steel is avoided;
opening a plugging stopper of a steel tapping hole 13, enabling molten steel to flow into a fine adjustment tundish 11, starting an oxygen combustion gun 25 to heat the molten steel in the fine adjustment tundish 11 to more than 1600 ℃, adding a deoxidizer, an alloy and a slagging auxiliary material in a storage bin 10 into the fine adjustment tundish 11 according to the requirements of molten steel components before tapping, and performing alloying component fine adjustment, recarburization and diffusion deoxidation on the molten steel;
when the components of the molten steel are fine-adjusted, the bottom blowing air brick 27 blows argon gas and is stirred, so that the temperature and the components of the molten steel are uniform, the alloy yield is high due to diffusion deoxidation, and less aluminum deoxidizers can be added, so that the molten steel has few inclusions;
during the tapping process and the fine adjustment of components, the oxygen combustion gun 25 is always in a working state, the air supply intensity can be adjusted according to heating requirements, the oxygen combustion ratio is controlled to be 1-1.01, a valve of the smoke return pipeline 23 is controlled by a pressure sensor in the fine adjustment tundish 11, the micro negative pressure is kept to be-20-30 Pa all the time, and not only is the situation that smoke cannot overflow out ensured, but also too much air cannot be sucked in; all the burnt high-temperature flue gas enters the coal gasification furnace 7 through the smoke return pipeline 23, and the high-temperature flue gas carries out dry distillation on low-sulfur coal powder to generate composite coal gas;
when the molten steel in the fine adjustment tundish 11 is enough for one pot of molten steel, a stopper rod at a steel outlet of the fine adjustment tundish 11 is opened, the molten steel flows into a ladle 12, the ladle 12 is transferred to an LF furnace station for refining, and final fine adjustment and waiting are carried out;
when the fine adjustment tundish 11 is replaced, the steel tapping hole 13 is plugged by a stopper rod to stop tapping, all molten steel in the fine adjustment tundish 11 is drained, then the fine adjustment tundish 11 is moved out and replaced, and the operation is reset to continue tapping continuously.
In the normal smelting process of the embodiment, 3 ladles of molten steel are discharged in 2 hours on average, and each ladle of molten steel has 60 tons of molten steel, which is just matched with the rear continuous casting. 1/3 local coking coal is injected into a gasification chamber, the coal injection amount is divided into 7 tons/hour, 9 tons/hour and 12 tons/hour, the larger the coal injection amount is, the higher the heat value of the coal gas is, the larger the gas production amount is, the larger the amount of generated dry distillation coal is, but the temperature drop of the flue gas is increased along with the increase of the coal injection amount, the oxygen supply amount is also larger, and therefore, the coal injection amount is also determined by the demand of a factory for the coal gas; the content of dust iron oxide in the dry distillation coal is low, most of the iron oxide is reduced into metal powder, and the heat value of the dry distillation coal is 6000-6300 kilocalories, so that the dry distillation coal has a good iron ore sintering effect.
Because of the slightly high sulfur of coal, SO in coal gas2Up to 500mg/m3The sulfur content of the molten steel exceeds the standard, so that SDS desulfurization equipment is added outside the smoke outlet of the shaft furnace, and a rear dust remover recovers desulfurization products and dust together. The recovered product is separated by water solution, the liquid water is used for other flue gas desulfurization by limestone-gypsum method in the factory and is used as a desulfurization promoter, the solid waste is ferric oxide and carbon powder, the iron oxide and the carbon powder are washed and then used for steel making and sintering, and no waste is discharged in the whole process.
Through heat calculation, the energy consumption of a melting link is 41 ten thousand kilocalories, which is equivalent to 58.7 kilograms of standard coal, the energy consumption is far lower than that of 280 kilograms of standard coal smelted by an electric arc furnace, the energy consumption of the process is only 21 percent of the average energy consumption of the electric arc furnace in China, and the energy-saving and emission-reducing effects are obvious.
Claims (9)
1. A self-generating coal gas circulation non-tail gas emission smelting steel scrap system is characterized by comprising a feeding system (1), a shaft furnace (2), a dust remover (3), a variable frequency induced draft fan (4), a coal gas cabinet (5), a chimney (6), a coal gasification furnace (7), a cyclone dust remover (8), a liftable heat preservation cover (9), a stock bin (10), a fine adjustment tundish (11) and a steel ladle (12);
a steel tapping hole (13) is formed in the side wall of the bottom of the shaft furnace (2), a molten steel heating oxy-combustion burner (14) is arranged at the lower part of a melting section of the shaft furnace (2), a main oxygen burner (15) is arranged at the upper part of the melting section of the shaft furnace (2), an annular flue (16) is arranged at the 1200-1700 ℃ temperature position of a transition section of the shaft furnace (2), a cooling spray system (17) is arranged at a preheating section of the shaft furnace (2), and a sealed charging system (18) is arranged at the top of the shaft furnace (2);
the coal gasification furnace (7) is provided with a coal injection gun (20), an oxygen nozzle (21) and a steam injection device (22);
the lifting heat-preserving cover (9) is provided with a temperature-measuring sampling port (24) and an oxygen combustion gun (25);
a steel flowing port (26) is formed in the lower portion of the side wall of the fine adjustment tundish (11), and bottom blowing air bricks (27) are arranged at the bottom of the fine adjustment tundish (11);
the feeding end of the feeding system (1) is connected with a sealed feeding system (18) at the top of the shaft furnace (2), a smoke outlet at the upper part of the shaft furnace (2) is connected with an air inlet of a dust remover (3) through a pipeline, an air outlet of the dust remover (3) is connected with an induced air port of a variable-frequency induced draft fan (4) through a pipeline, an air inlet pipe (19) is arranged on a connecting pipeline of the dust remover (3) and the variable-frequency induced draft fan (4), and an air outlet of the variable-frequency induced draft fan (4) is respectively connected with a gas cabinet (5) and a chimney (6) through pipelines;
the lower flue of the annular flue (16) is sequentially connected with a coal gasification furnace (7) and a cyclone dust collector (8) through pipelines, and the cyclone dust collector (8) is connected with the upper flue of the annular flue (16) through a return flue gas pipeline;
a tapping hole (13) of the shaft furnace (2) is connected with a fine adjustment tundish (11) through a pipeline, a liftable heat preservation cover (9) is covered on the fine adjustment tundish (11), an auxiliary material feeding hole on the liftable heat preservation cover (9) is connected with a bottom discharge hole of the storage bin (10) through a pipeline, and a smoke return hole on the liftable heat preservation cover (9) is connected with an annular flue (16) through a smoke return pipeline (23);
a steel ladle (12) is arranged below a steel flowing port (26) of the fine adjustment tundish (11) and is used for receiving molten steel.
2. The self-generating coal gas circulation non-tail gas emission smelting steel scrap system according to claim 1, wherein a gas control valve is arranged at a gas outlet of the dust remover (3), a gas control valve is arranged at the gas inlet pipe (19), a gas control valve is arranged on a connecting pipeline of the variable frequency induced draft fan (4) and the gas tank (5), and a gas control valve is arranged on a connecting pipeline of the variable frequency induced draft fan (4) and the chimney (6); the lower flue smoke outlet of the annular flue (16) is provided with a gas control valve, and the upper flue smoke inlet of the annular flue (16) is provided with a gas control valve.
3. The self-generating gas circulation non-exhaust emission steel smelting waste system according to claim 1, characterized in that the tap hole (13) of the shaft furnace (2) is provided with a plugging stopper rod; a stopper rod is arranged outside the steel flowing port (26) of the fine adjustment tundish (11).
4. The self-generating gas circulation non-tail gas emission smelting steel waste system according to claim 1, characterized in that a water source is communicated with the tail end of the cooling spray system (17).
5. The self-generating gas circulation non-exhaust emission smelting steel scrap system according to claim 1, characterized in that the smelting zone of the shaft furnace (2) is provided with a runner which is covered with a refractory cover plate.
6. The self-generating coal gas circulation non-tail gas emission smelting steel scrap system according to claim 1, wherein a dry distillation coal collection bin, a carbon powder cooling and recovering device and a temperature sensor are further arranged inside the coal gasification furnace (7).
7. The self-generating gas circulation non-tail gas emission smelting steel scrap system according to claim 1, wherein the number of the molten steel heating oxygen combustion burner (14) and the number of the main oxygen burner (15) are determined according to the equipment scale size of the shaft furnace (2); the number of the coal injection guns (20), the number of the oxygen nozzles (21) and the number of the steam injection devices (22) are determined according to the equipment scale of the coal gasification furnace (7).
8. The self-generating gas circulation non-tail gas emission smelting steel scrap system according to claim 1, wherein the molten steel heating oxygen combustion burner (14) is replaced by an oxygen combustion gun; the primary oxygen burner (15) is replaced by an oxygen lance.
9. The self-generating gas-cycle off-gas emission-free steel smelting waste system according to claim 1, wherein the fine tuning tundish (11) is replaced with a ladle (12).
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