Direct-current submerged arc furnace tail gas recycling system and method thereof

Abstract

The invention discloses a direct current submerged arc furnace tail gas recycling system and a method thereof, after tail gas generated by a direct current submerged arc furnace is purified, according to actual operation parameters of the system, the gas amount of a power generation branch and the gas amount of a blending combustion branch are respectively regulated and controlled by utilizing a power generation branch dynamic regulation and control strategy and a blending combustion branch dynamic regulation and control strategy; the requirement for the temperature in the shaft furnace is met, meanwhile, it is guaranteed that the generator set maintains the relatively high power generation efficiency, and energy waste is avoided; besides supplying power to the direct-current submerged arc furnace, the extra power can also supply power to other electric equipment in an enterprise, so that the dependence of the enterprise on external energy sources can be reduced, and the production cost is saved. The actual situation in the system operation process is fully considered, the distribution amount is adjusted in time, the situation that stable operation of the shaft furnace cannot be met when a fixed distribution proportion is adopted is avoided, energy carried by coal gas can be utilized to the maximum degree, energy waste is reduced, and pollution to the environment is reduced.

Description

Technical Field

[0001] The present invention relates to the field of tail gas recycling, and in particular to a direct current ore-fired furnace tail gas recycling system and method. Background Art

[0002] High-carbon chromium alloy is a raw material for smelting stainless steel. High-carbon chromium alloy smelting methods include blast furnace, submerged arc furnace, plasma furnace, and molten reduction. Our company currently uses the solvent method to smelt high-carbon chromium alloy in a submerged arc furnace. In the molten reduction method, the chromite ore is ball-milled, and then bentonite and magnesia powder are added in appropriate proportions. The mixture is then screened and pelletized to produce shaft furnace oxidized pellets. These oxidized pellets are then transferred from the top of the shaft furnace into the shaft furnace, where they undergo a reduction reaction and sintering to form chromium pellets. The chromium pellets are then used as raw material, silica as a slag-forming flux, and a carbonaceous reducing agent (coke) in an electrically heated, direct current submerged arc furnace for carbon reduction, yielding the high-carbon chromium alloy.

[0003] During the operation of a DC submerged arc furnace, a large amount of raw materials undergo chemical reactions under high temperature conditions, generating a large amount of exhaust gas. This exhaust gas is rich in energy. Its main components include combustible gases such as carbon monoxide and hydrogen, as well as small amounts of pollutants such as dust, sulfur oxides, and nitrogen oxides. The volume fraction of carbon monoxide can reach 70%-80%, and the volume fraction of hydrogen is approximately 3%-8%. Based on average calorific value, the calorific value of high-carbon ferrochrome closed furnace gas is approximately 11076kJ / Nm3, which has huge energy recovery potential.

[0004] However, current methods for treating exhaust gas from DC blast furnaces are largely crude. Traditional treatment methods primarily discharge the exhaust directly into the atmosphere, wasting valuable energy resources and causing significant environmental pollution. Some companies have attempted a simple combustion method, igniting the exhaust gas in a chimney before discharging it. While this method reduces carbon monoxide emissions to some extent, it fails to effectively utilize the heat in the exhaust gas, resulting in a significant waste of energy. Furthermore, because the exhaust gas contains impurities such as dust, it can easily clog and corrode combustion equipment during the combustion process, increasing maintenance costs and downtime. Some companies have also attempted to reuse this exhaust gas for co-firing in the vertical furnace, but without precise and dynamic control of the co-firing ratio. Due to fluctuations in the raw materials and furnace conditions of the DC blast furnace, the calorific value of the exhaust gas fluctuates. If a fixed co-firing ratio is used, low exhaust gas calorific values will not meet the required vertical furnace temperature, making stable combustion difficult. High exhaust gas calorific values will also result in excessively high vertical furnace temperatures, making stable combustion equally difficult.

[0005] In view of the above problems, there is an urgent need to develop an efficient and environmentally friendly direct current submerged arc furnace tail gas regeneration and utilization system and method. Summary of the Invention

[0006] The first object of the present invention is to provide a DC ore-fired furnace tail gas regeneration and utilization system; the second object of the present invention is to provide a DC ore-fired furnace tail gas regeneration and utilization method.

[0007] The first object of the present invention is implemented by the following technical solutions: A DC ore-fired furnace tail gas recycling system comprises a vertical furnace, a batching bin, a charging device, and a DC ore-fired furnace, wherein the bottom discharge port of the vertical furnace is connected to the feed port of the batching bin, the discharge port of the batching bin is connected to the feed port of the charging device, and the discharge port of the charging device is connected to the top feed port of the DC ore-fired furnace; the air inlet of the blower is connected to the outside, the air outlet of the blower is connected to the cold medium inlet of an air preheater, and the cold medium outlet of the air preheater and the gas outlet of the fuel gas source are both connected to the air inlet of a mixer via pipelines; It also includes a gas pre-treatment unit, a gas cabinet, a gas finishing unit, a generator set and a control unit; The tail gas outlet of the direct current ore-fired furnace is connected to the air inlet of the inertial settling tank of the gas pretreatment unit via a pipeline. The air outlet of the electric tar precipitator of the gas pretreatment unit is connected to the air inlet of the gas holder. The air outlet of the gas holder is divided into two routes. The first route is connected to the air inlet of the mixer via a pipeline. The air outlet of the mixer is connected to the fuel gas inlet of the vertical furnace. The second route is connected to the inlet of the dust filter of the gas polishing unit via a pipeline. The air outlet of the compressor of the gas polishing unit is connected to the fuel gas inlet of the generator set. The control unit includes a pressure sensor provided in the gas tank, a flow sensor and a calorific value analyzer provided at the fuel gas inlet of the generator set, a thermocouple provided at the furnace waist of the vertical furnace, a power analyzer provided at the power output end of the generator set, an online gas analyzer provided at the exhaust gas outlet of the vertical furnace, a blending flow regulating valve provided on the pipeline connecting the gas tank and the mixer, a fuel gas flow regulating valve provided on the pipeline connecting the fuel gas source and the mixer, and a power generation flow regulating valve provided at the fuel gas inlet of the generator set; The signal output ends of the pressure sensor, the flow sensor, the calorific value analyzer, the thermocouple, the power analyzer and the online gas analyzer are all connected to the signal input ends of the controller, and the signal output ends of the controller are respectively connected to the signal input ends of the blending flow control valve, the fuel gas flow control valve, the power generation flow control valve and the frequency converter of the blower.

[0008] Furthermore, the coal gas pretreatment unit includes an inertial settling tank, an air cyclone cooling dust collector and an electric tar precipitator connected in series.

[0009] Furthermore, the coal gas finishing unit includes a dust filter, a carbon dioxide adsorption tower, a tar filter and a compressor connected in series.

[0010] Furthermore, the power output end of the generator set is electrically connected to the power input end of the transformer substation, the power output end of the transformer substation is connected to the power input end of the distribution network; the power output end of the distribution network is electrically connected to the power input end of the DC submerged arc furnace.

[0011] Furthermore, the exhaust gas discharge port of the vertical furnace is connected to the heat medium inlet of the air preheater through a pipeline.

[0012] The second object of the present invention is implemented by the following technical solutions: A method for recycling exhaust gas from a DC submerged arc furnace comprises: the shaft furnace oxidized pellets formed by sintering in the shaft furnace enter a batching bin to participate in batching; after batching, the pellets are fed into the DC submerged arc furnace by a feeding device for smelting to obtain a high-carbon chromium alloy; the high-temperature exhaust gas discharged from the shaft furnace enters an air preheater as a heat medium to exchange heat with the combustion-supporting air entering the shaft furnace; The exhaust gas from the DC submerged arc furnace is initially cooled, dusted, and decoked by the gas pretreatment unit before being sent to a gas tank for buffering. Part of the gas in the gas tank is fed into the vertical furnace for blending, while part of the gas is refined to remove dust, tar, and carbon dioxide before being sent to the generator set for power generation, thus supplying power to the DC submerged arc furnace. The amount of gas used for power generation and co-firing is allocated through the gas distribution method.

[0013] Furthermore, the gas distribution method includes the following steps: S1. Data Collection: Real-time operating data during system operation is collected. The real-time operating data includes the pressure in the gas tank collected using a pressure sensor, the gas flow rate and calorific value of the gas entering the generator set collected using a flow sensor and a calorific value analyzer, respectively, the temperature at the waist of the shaft furnace collected using a thermocouple, the output power of the generator set collected using a power analyzer, and the carbon monoxide and oxygen contents in the exhaust gas discharged from the shaft furnace collected using an online gas analyzer. S2. Determine whether to start dynamic allocation: Determine whether dynamic allocation conditions are met based on the real-time operating data collected in S1. Data collection. If not, allocate the gas volume for power generation and blending according to the initial allocation method, and continue with S2. If satisfied, preliminarily allocate the gas volume for power generation and blending according to the fixed allocation method, and execute S3 after a certain period of time. S3. Dynamic allocation: The gas volume of the power generation branch and the gas volume of the blending branch are regulated by using the dynamic control strategy of the power generation branch and the dynamic control strategy of the blending branch, wherein: The dynamic control strategy of the power generation branch includes the following steps: S311. Calculate the initial gas flow required by the generator set using formula (1) based on the calorific value of the gas entering the generator set. ; (1) In formula (1), Pmax is the maximum power of the generator set, is the calorific value of the gas initially entering the generator set, is the default initial power generation efficiency; S312, using formula (2) to calculate the initial gas flow required by the generator set calculated in S311 The corresponding opening size of the power generation flow control valve ; (2) In formula (2), It is the maximum flow rate when the power generation flow control valve is fully opened. is the maximum opening of the power generation flow control valve; S313, adjusting the opening of the power generation flow regulating valve to the opening calculated in S312 , after a certain period of time, execute S314; S314, according to the real-time flow of gas entering the generator set , calorific value and the real-time output power of the generator set , use formula (3) to calculate the real-time power generation efficiency of the generator set at this time , and execute S315; (3) S315: Real-time power generation efficiency calculated according to S314 and S1, the real-time pressure value of the gas tank collected in data collection , dynamically control the power generation flow regulating valve, the specific method is: when ≥45% or When the pressure is ≥10kPa, the opening of the power generation flow control valve is increased by 5%, and S314 is executed after a certain period of time; when <30% or When the pressure is less than 3 kPa, the opening of the power generation flow control valve is reduced by 5%, and S314 is executed after a certain period of time; In other cases, no adjustment is performed, and S314 is executed after a certain period of time; The dynamic control strategy of the blending branch is: According to the temperature at the waist of the vertical furnace collected in the S1 data collection and the carbon monoxide content in the exhaust gas emitted from the shaft furnace and oxygen content , dynamically adjust the operating frequency of the blending flow control valve, fuel gas flow control valve and blower inverter. The specific method is: when ≥1400℃ or When the value is greater than 0.5%, the fuel gas flow control valve is opened by 3%, the co-combustion flow control valve is opened by 10%, and the blower inverter operating frequency is increased by 5%. After a certain period of time, S314 is executed. when <1300℃ or When the value is greater than 3%, the fuel gas flow control valve is opened by 3%, the co-combustion flow control valve is opened by 10%, and the blower inverter operating frequency is reduced by 5%. After a certain period of time, S314 is executed. In other cases, no adjustment is performed, and S314 is executed after a certain period of time.

[0014] Furthermore, in step S2, it is determined whether dynamic allocation is started. The dynamic allocation condition is: the pressure in the gas tank is ≥3kPa; The fixed allocation method is: the openings of the blending flow control valve, the power generation flow control valve and the fuel gas flow control valve are all set to 50%; The initial distribution method is: setting the openings of the blending flow control valve and the power generation flow control valve to 0, and setting the opening of the fuel gas flow control valve to 100%.

[0015] Furthermore, the real-time power generation efficiency calculated in S314 is If the rate remains below 30% for 3 consecutive hours, an early warning will be issued.

[0016] Advantages of the present invention: In the present invention, the tail gas generated by the DC ore-fired furnace enters the gas tank after purification treatment, and the gas volume of the power generation branch and the gas volume of the blending branch are respectively regulated by utilizing the dynamic control strategy of the power generation branch and the dynamic control strategy of the blending branch according to the actual operating parameters of the system. While meeting the temperature requirements in the vertical furnace, it is ensured that the generator set maintains a relatively high power generation efficiency and does not cause energy waste. In addition to powering the DC ore-fired furnace, the generated electricity can also power other electrical equipment in the enterprise, thereby reducing the enterprise's dependence on external energy and saving production costs.

[0017] In the process of dynamically allocating the amount of coal gas used for power generation and blending, the present invention fully considers the actual situation during system operation and makes timely adjustments to the allocation amount, thereby avoiding the problem of being unable to meet the requirements of stable operation of the vertical furnace due to fluctuations in raw materials, furnace conditions, etc. when using a fixed allocation ratio. It also enables the energy carried by the coal gas to be utilized to the maximum value, reduces energy waste, reduces environmental pollution, and achieves a win-win situation in economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of system connections in Example 1; Figure 2 This is the signal control principle diagram of Example 1.

[0019] In the figure: vertical furnace 1, batching bin 2, charging device 3, direct current ore-fired furnace 4, coal gas pretreatment unit 5, inertial settling tank 51, air cyclone cooling dust collector 52, electric tar collector 53, gas cabinet 6, coal gas finishing unit 7, dust filter 71, carbon dioxide adsorption tower 72, tar filter 73, compressor 74, generator set 8, control unit 9, pressure sensor 91, flow sensor 92, calorific value analyzer 93, thermocouple 94, power analyzer 95, online gas analyzer 96, controller 97, co-combustion flow regulating valve 98, fuel gas flow regulating valve 99, power generation flow regulating valve 910, blower 10, air preheater 11, mixer 12, substation 13, distribution network 14, fuel gas source 15. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1 、 Figure 2A DC ore-fired furnace tail gas recycling system is shown, comprising a vertical furnace 1, a batching bin 2, a charging device 3 and a DC ore-fired furnace 4. The bottom discharge port of the vertical furnace 1 is connected to the feed port of the batching bin 2, the discharge port of the batching bin 2 is connected to the feed port of the charging device 3, and the discharge port of the charging device 3 is connected to the top feed port of the DC ore-fired furnace 4; the air inlet of the blower 10 is connected to the outside, the air outlet of the blower 10 is connected to the cold medium inlet of the air preheater 11, the cold medium outlet of the air preheater 11 and the air outlet of the fuel gas source 15 are both connected to the air inlet of the mixer 12 through pipelines; the exhaust gas discharge port of the vertical furnace 1 is connected to the hot medium inlet of the air preheater 11 through a pipeline.

[0022] This embodiment further includes a gas pre-treatment unit 5, a gas tank 6, a gas polishing unit 7, a generator set 8, and a control unit 9. The gas pre-treatment unit 5 includes an inertial settling tank 51, an air cyclone cooling dust collector 52, and an electrostatic tar precipitator 53 connected in series. The gas polishing unit 7 includes a dust filter 71, a carbon dioxide adsorption tower 72, a tar filter 73, and a compressor 74 connected in series. The gas tank 6 in this embodiment is a dry rubber membrane gas tank.

[0023] The tail gas outlet of the DC submerged arc furnace 4 is connected to the air inlet of the inertial settling tank 51 of the gas pretreatment unit 5 through a pipeline. The air outlet of the electric tar collector 53 of the gas pretreatment unit 5 is connected to the air inlet of the gas tank 6. The air outlet of the gas tank 6 is divided into two routes. The first route is connected to the air inlet of the mixer 12 through a pipeline. The air outlet of the mixer 12 is connected to the fuel gas inlet of the vertical furnace 1. The second route is connected to the inlet of the dust filter 71 of the gas polishing unit 7 through a pipeline. The air outlet of the compressor 74 of the gas polishing unit 7 is connected to the fuel gas inlet of the generator set 8; the power output end of the generator set 8 is electrically connected to the power input end of the substation 13, and the power output end of the substation 13 is connected to the power input end of the distribution network 14; the power output end of the distribution network 14 is electrically connected to the power input end of the DC submerged arc furnace 4 and other electrical equipment in the factory.

[0024] The control unit 9 includes a pressure sensor 91 provided in the gas tank 6, a flow sensor 92 and a calorific value analyzer 93 provided at the fuel gas inlet of the generator set 8, a thermocouple 94 provided at the waist of the vertical furnace 1, a power analyzer 95 provided at the power output end of the generator set 8, an online gas analyzer 96 provided at the exhaust gas outlet of the vertical furnace 1, a blending flow regulating valve 98 provided on the pipeline connecting the gas tank 6 and the mixer 12, a fuel gas flow regulating valve 99 provided on the pipeline connecting the fuel gas source 15 and the mixer 12, and a power generation flow regulating valve 910 provided at the fuel gas inlet of the generator set 8. The signal output ends of the pressure sensor 91, flow sensor 92, calorific value analyzer 93, thermocouple 94, power analyzer 95 and online gas analyzer 96 are all connected to the signal input ends of the controller 97. The signal output ends of the controller 97 are respectively connected to the signal input ends of the blending flow control valve 98, the fuel gas flow control valve 99, the power generation flow control valve 910 and the frequency converter of the blower 10.

[0025] Example 2 The exhaust gas regeneration system for a DC submerged arc furnace provided in Example 1 is used to recycle the exhaust gas from the DC submerged arc furnace. The exhaust gas is regenerated as follows: sintered shaft furnace oxidized pellets formed in a shaft furnace 1 enter a batching bin 2 for batching. After batching, the batching is fed by a feeding device 3 into a DC submerged arc furnace 4 for smelting to produce a high-carbon chromium alloy. High-temperature exhaust gas discharged from the shaft furnace 1 enters an air preheater 11 as a heat medium for heat exchange with the combustion-supporting air entering the shaft furnace 1. The exhaust gas at about 550°C discharged from the DC submerged arc furnace 4 is initially cooled to below 200°C after the waste heat is recovered by the waste heat recovery device in the gas pretreatment unit 5. The exhaust gas then enters the inertial settling tank 51 for rough dust removal of larger dust particles. The high-temperature flue gas is then cooled by the air cyclone cooling dust collector 52, and the dust is further cyclone-separated and dusted to further remove large dust particles, reducing the dust content in the exhaust gas to 50mg / Nm 3 The cooling air volume of the air cyclone cooling dust collector 52 is controlled in real time by a variable frequency speed regulating motor to reduce the temperature to below 45°C; then, the air enters the electric tar collector 53 for decoking, and the tar content is reduced to 20mg / Nm 3 Next, the gas is sent to the gas tank 6 for buffering; part of the gas in the gas tank 6 enters the vertical furnace 1 for mixed combustion, and part of it passes through the dust filter 71, the carbon dioxide adsorption tower 72, and the tar filter 73 for fine treatment to further remove dust, tar, and carbon dioxide that affects the calorific value, so that the dust content in the exhaust gas is reduced to 10mg / Nm 3 Below, the tar content is reduced to 8mg / Nm 3 Next, the gas is pressurized by the compressor 74 and then fed into the generator set 8 for power generation, thereby supplying power to the DC ore-fired furnace 4 and other electrical equipment within the plant. In this embodiment, the amount of gas used for power generation and blending is distributed by a gas distribution method.

[0026] The gas distribution method comprises the following steps: S1. Data Collection: Real-time operating data during system operation is collected. The real-time operating data includes the pressure in the gas tank 6 collected by the pressure sensor 91, the gas flow rate and calorific value of the gas entering the generator set 8 collected by the flow sensor 92 and the calorific value analyzer 93 respectively, the temperature at the waist of the shaft furnace 1 collected by the thermocouple 94, the output power of the generator set 8 collected by the power analyzer 95, and the carbon monoxide and oxygen contents in the exhaust gas discharged from the shaft furnace 1 collected by the online gas analyzer 96; S2. Determine whether to start dynamic allocation: Determine whether the dynamic allocation conditions are met based on the real-time operating data collected in S1. Data collection. If not, allocate the gas volume for power generation and blending according to the initial allocation method and continue with S2. If satisfied, preliminarily allocate the gas volume for power generation and blending according to the fixed allocation method and execute S3 after 1 hour. The dynamic allocation conditions are: the pressure in the gas tank 6 ≥ 3kPa; The fixed allocation method is: the openings of the blending flow control valve 98, the power generation flow control valve 910 and the fuel gas flow control valve 99 are all set to 50%; The initial allocation method is: set the opening of the blending flow control valve 98 and the power generation flow control valve 910 to 0, and set the opening of the fuel gas flow control valve 99 to 100%.

[0027] S3. Dynamic allocation: The gas volume of the power generation branch and the gas volume of the blending branch are regulated by using the dynamic control strategy of the power generation branch and the dynamic control strategy of the blending branch, wherein: The dynamic control strategy of the power generation branch includes the following steps: S311. Calculate the initial gas flow required by the generator set 8 using formula (1) based on the calorific value of the gas entering the generator set 8. ; (1) In formula (1), is the maximum power of generator set 8, is the calorific value of the coal gas initially entering the generator set 8, is the default initial power generation efficiency of the generator set 8, which is set to 40% in this embodiment; S312, using formula (2) to calculate the initial gas flow required by generator set 8 calculated in S311 The corresponding opening size of the power generation flow control valve 910 ; (2) In formula (2), is the maximum flow rate when the power generation flow control valve 910 is fully opened, is the maximum opening of the power generation flow control valve 910, which is set to 100% by default in this embodiment; S313, adjust the opening of the power generation flow control valve 910 to the opening size calculated in S312 , execute S314 after 1 hour; S314, according to the real-time flow of the gas entering the generator set 8 , calorific value And the real-time output power of generator set 8 , use formula (3) to calculate the real-time power generation efficiency of generator set 8 at this time , and execute S315; (3) The real-time power generation efficiency calculated in S314 If the rate remains below 30% for 3 consecutive hours, an early warning will be issued.

[0028] S315: Real-time power generation efficiency calculated according to S314 and S1, the real-time pressure value of gas tank 6 collected in data collection , dynamically regulate the power generation flow control valve 910, the specific method is: when ≥45% or When the pressure is ≥10 kPa, the opening of the power generation flow control valve 910 is increased by 5%, and S314 is executed after 1 hour; when <30% or When the pressure is less than 3 kPa, the opening of the power generation flow control valve 910 is reduced by 5%, and S314 is executed after 1 hour; In other cases, no adjustment is made and S314 is executed after 1 hour. The dynamic control strategy of the blending branch is: According to the temperature at the waist of the vertical furnace 1 collected in S1 data collection and the carbon monoxide content in the exhaust gas emitted from the shaft furnace 1 and oxygen content , dynamically adjust the operating frequency of the blending flow control valve 98, the fuel gas flow control valve 99 and the frequency converter of the blower 10, and the specific method is as follows: when ≥1400℃ or >0.5%, reduce the opening of the fuel gas flow control valve 99 by 3%, increase the opening of the co-combustion flow control valve 98 by 10%, and increase the operating frequency of the inverter of the blower 10 by 5%. After 1 hour, execute S314; when <1300℃ or >3%, increase the opening of the fuel gas flow control valve 99 by 3%, decrease the opening of the co-combustion flow control valve 98 by 10%, and decrease the operating frequency of the inverter of the blower 10 by 5%. After 1 hour, execute S314; In other cases, no adjustment is performed, and S314 is executed after 1 hour.

[0029] In this embodiment, in the initial stage of system operation, the amount of gas in the gas tank 6 is relatively small and cannot meet the gas volume requirements for power generation and co-combustion. Therefore, dynamic allocation is not performed. At this time, the gas is not used for power generation and co-combustion, and the fuel gas in the vertical furnace 1 is supplied by the fuel gas source 15. Dynamic allocation is only performed when the amount of gas in the gas tank 6 is relatively large. Therefore, in the present invention, dynamic allocation conditions are established to determine whether to enable the dynamic allocation method.

[0030] At the beginning of dynamic allocation, because no gas has previously entered generator set 8, the amount of gas entering generator set 8 cannot be regulated based on the real-time power generation efficiency of generator set 8. Therefore, the openings of the co-combustion flow control valve 98, the power generation flow control valve 910, and the fuel gas flow control valve 99 are regulated according to a fixed allocation method. After the fixed allocation method has been in operation for a period of time, the amount of gas used for power generation and co-combustion, as well as the amount of fuel gas supplied to the shaft furnace 1 by the fuel gas source 15, are regulated according to the dynamic control strategy.

[0031] During the dynamic allocation process, the initial gas flow required by generator set 8 and the corresponding opening of the power generation flow control valve 910 are first calculated based on the calorific value of the gas entering generator set 8 during the fixed allocation process, the maximum power of generator set 8, and the default initial power generation efficiency of generator set 8. The opening of the power generation flow control valve 910 is then adjusted accordingly. After a period of adjustment, the power generation efficiency of generator set 8 is calculated using the real-time operating parameters of generator set 8. The status of generator set 8 is then determined based on the power generation efficiency, and the amount of gas used for power generation is dynamically adjusted based on the gas volume in the gas tank 6. When the power generation efficiency is high or the pressure in the gas tank is too high, the opening of the power generation flow control valve 910 can be increased to increase the amount of gas used for power generation, thereby fully utilizing the efficient power generation state. When the power generation efficiency is low or the gas volume is insufficient, the gas is prioritized for co-combustion. Therefore, to avoid energy waste, the opening of the power generation flow control valve 910 can be reduced to reduce the gas flow in the power generation branch. If the power generation efficiency remains low, it may be due to a fault in the power generation equipment or poor operating conditions, and an early warning will be issued. Remind staff to start the inspection procedure for power generation equipment, including the exhaust combustion condition, the wear of equipment components (such as pistons and valves of internal combustion engines), whether the cooling system is normal, etc. Through the fault diagnosis system or manual inspection, determine the cause of the decline in power generation efficiency and make timely repairs or adjustments.

[0032] Meanwhile, for the co-combustion branch, if the temperature at the waist of shaft furnace 1 is detected to be too high or the carbon monoxide content in the tail gas of shaft furnace 1 is too high, it is determined that the amount of fuel gas supplied to shaft furnace 1 is too large or the calorific value is too high, resulting in excessively high temperature or incomplete combustion of CO. To improve gas utilization, the supply of fuel gas source 15 can be reduced, the supply of co-combustion gas can be appropriately increased, and the amount of combustion air entering shaft furnace 1 can be increased by increasing the operating frequency of the inverter of blower 10. If the temperature at the waist of shaft furnace 1 is detected to be too low or the oxygen content in the tail gas of shaft furnace 1 is too high, it is determined that the amount of fuel gas supplied to shaft furnace 1 is too small or the calorific value is too low, resulting in excessively low temperature or incomplete combustion of oxygen. To ensure the temperature requirements of shaft furnace 1, the supply of fuel gas source 15 can be appropriately increased, the supply of co-combustion gas can be reduced, and the operating frequency of the inverter of blower 10 can be reduced to reduce the amount of combustion air entering shaft furnace 1.

[0033] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A DC submerged arc furnace tail gas recycling system, comprising a vertical furnace, a batching bin, a loading device, and a DC submerged arc furnace, wherein the bottom discharge port of the vertical furnace is connected to the feed port of the batching bin, the discharge port of the batching bin is connected to the feed port of the loading device, and the discharge port of the loading device is connected to the top feed port of the DC submerged arc furnace; the air inlet of a blower is connected to the outside, the air outlet of the blower is connected to the cold medium inlet of an air preheater, and the cold medium outlet of the air preheater and the gas outlet of the fuel gas source are both connected to the air inlet of a mixer via pipelines; It is characterized by: It also includes a gas pre-treatment unit, a gas cabinet, a gas finishing unit, a generator set and a control unit; The tail gas outlet of the direct current ore-fired furnace is connected to the air inlet of the inertial settling tank of the gas pretreatment unit through a pipeline. The air outlet of the electric tar precipitator of the gas pretreatment unit is connected to the air inlet of the gas holder. The air outlet of the gas holder is divided into two routes. The first route is connected to the air inlet of the mixer through a pipeline. The air outlet of the mixer is connected to the fuel gas inlet of the vertical furnace. The second route is connected to the inlet of the dust filter of the gas polishing unit through a pipeline. The air outlet of the compressor of the gas polishing unit is connected to the fuel gas inlet of the generator set. The control unit includes a pressure sensor provided in the gas tank, a flow sensor and a calorific value analyzer provided at the fuel gas inlet of the generator set, a thermocouple provided at the furnace waist of the vertical furnace, a power analyzer provided at the power output end of the generator set, an online gas analyzer provided at the exhaust gas outlet of the vertical furnace, a blending flow regulating valve provided on the pipeline connecting the gas tank and the mixer, a fuel gas flow regulating valve provided on the pipeline connecting the fuel gas source and the mixer, and a power generation flow regulating valve provided at the fuel gas inlet of the generator set; The signal output ends of the pressure sensor, the flow sensor, the calorific value analyzer, the thermocouple, the power analyzer and the online gas analyzer are all connected to the signal input ends of the controller, and the signal output ends of the controller are respectively connected to the signal input ends of the blending flow control valve, the fuel gas flow control valve, the power generation flow control valve and the frequency converter of the blower.

2. A direct current submerged arc furnace tail gas regeneration and utilization system according to claim 1, characterized in that: The coal gas pretreatment unit comprises an inertial settling tank, an air cyclone cooling dust collector and an electric tar precipitator which are connected in series.

3. The DC submerged arc furnace tail gas regeneration and utilization system according to claim 1, characterized in that: The coal gas finishing unit comprises a dust filter, a carbon dioxide adsorption tower, a tar filter and a compressor which are connected in series.

4. The DC submerged arc furnace tail gas regeneration and utilization system according to claim 1, characterized in that: The power output end of the generator set is electrically connected to the power input end of the transformer substation, the power output end of the transformer substation is connected to the power input end of the distribution network; the power output end of the distribution network is electrically connected to the power input end of the DC submerged arc furnace.

5. The DC submerged arc furnace tail gas regeneration and utilization system according to claim 1, characterized in that: The exhaust gas discharge port of the vertical furnace is connected to the heat medium inlet of the air preheater through a pipeline.

6. A method for regenerating and utilizing exhaust gas from a DC ore-fired furnace, comprising: The shaft furnace oxidized pellets formed by sintering in the shaft furnace enter the batching bin to participate in batching. After batching, they are sent into the DC submerged arc furnace by the feeding device for smelting to obtain high carbon chromium alloy. The feature is that the high-temperature tail gas discharged from the shaft furnace enters the air preheater as a heat medium to exchange heat with the combustion air entering the shaft furnace; The exhaust gas from the DC submerged arc furnace is initially cooled, dusted, and decoked by the gas pretreatment unit before being sent to a gas tank for buffering. Part of the gas in the gas tank is fed into the vertical furnace for blending, while part of the gas is refined to remove dust, tar, and carbon dioxide before being sent to the generator set for power generation, thus supplying power to the DC submerged arc furnace. The amount of gas used for power generation and co-firing is allocated through the gas distribution method.

7. The method for regenerating and utilizing the exhaust gas from a direct current submerged arc furnace according to claim 6, wherein: The gas distribution method comprises the following steps: S1. Data Collection: Real-time operating data during system operation is collected. The real-time operating data includes the pressure in the gas tank collected by a pressure sensor, the gas flow rate and gas calorific value entering the generator set collected by a flow sensor and a calorific value analyzer, respectively, the temperature at the waist of the shaft furnace collected by a thermocouple, the output power of the generator set collected by a power analyzer, and the carbon monoxide and oxygen contents in the exhaust gas discharged from the shaft furnace collected by an online gas analyzer. S2. Determine whether to start dynamic allocation: Determine whether dynamic allocation conditions are met based on the real-time operating data collected in S1. Data collection. If not, allocate the gas volume for power generation and blending according to the initial allocation method, and continue with S2. If satisfied, preliminarily allocate the gas volume for power generation and blending according to the fixed allocation method, and execute S3 after a certain period of time. S3. Dynamic allocation: The gas volume of the power generation branch and the gas volume of the blending branch are regulated by using the dynamic control strategy of the power generation branch and the dynamic control strategy of the blending branch, wherein: The dynamic control strategy of the power generation branch includes the following steps: S311. Calculate the initial gas flow required by the generator set using formula (1) based on the calorific value of the gas entering the generator set. ; （1） In formula (1), Pmax is the maximum power of the generator set, is the calorific value of the gas initially entering the generator set, is the default initial power generation efficiency; S312, using formula (2) to calculate the initial gas flow required by the generator set calculated in S311 The corresponding opening size of the power generation flow control valve ; （2） In formula (2), It is the maximum flow rate when the power generation flow control valve is fully opened. is the maximum opening of the power generation flow control valve; S313, adjusting the opening of the power generation flow regulating valve to the opening calculated in S312 , after a certain period of time, execute S314; S314, according to the real-time flow of gas entering the generator set , calorific value and the real-time output power of the generator set , use formula (3) to calculate the real-time power generation efficiency of the generator set at this time , and execute S315; （3） S315: Real-time power generation efficiency calculated according to S314 and the real-time pressure value of the gas tank collected in S1 and data collection , dynamically control the power generation flow regulating valve, the specific method is: when ≥45% or When the pressure is ≥10kPa, the opening of the power generation flow control valve is increased by 5%, and S314 is executed after a certain period of time; when <30% or When the pressure is less than 3 kPa, the opening of the power generation flow control valve is reduced by 5%, and S314 is executed after a certain period of time; In other cases, no adjustment is performed, and S314 is executed after a certain period of time. The dynamic control strategy of the blending branch is: According to the temperature at the waist of the vertical furnace collected in the S1 data collection and the carbon monoxide content in the exhaust gas emitted from the shaft furnace and oxygen content , dynamically adjust the operating frequency of the blending flow control valve, fuel gas flow control valve and blower inverter. The specific method is: when ≥1400℃ or When the value is greater than 0.5%, the fuel gas flow control valve is opened by 3%, the co-combustion flow control valve is opened by 10%, and the blower inverter operating frequency is increased by 5%. After a certain period of time, S314 is executed. when <1300℃ or When the value is greater than 3%, the fuel gas flow control valve is opened by 3%, the co-combustion flow control valve is opened by 10%, and the blower inverter operating frequency is reduced by 5%. After a certain period of time, S314 is executed. In other cases, no adjustment is performed, and S314 is executed after a certain period of time.

8. The method for regenerating and utilizing the exhaust gas from a direct current submerged arc furnace according to claim 7, wherein: S2: Determine whether to start dynamic allocation. The dynamic allocation condition is: the pressure in the gas tank is ≥3kPa; The fixed allocation method is: the openings of the blending flow control valve, the power generation flow control valve and the fuel gas flow control valve are all set to 50%; The initial distribution method is: setting the openings of the blending flow control valve and the power generation flow control valve to 0, and setting the opening of the fuel gas flow control valve to 100%.

9. The method for regenerating and utilizing the exhaust gas from a direct current submerged arc furnace according to claim 7, wherein: As the real-time power generation efficiency calculated in S314 If the rate remains below 30% for 3 consecutive hours, an early warning will be issued.

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