A gas-electric co-operated steel melting device

Abstract

This utility model discloses a gas-electric co-operated steel melting device. By simultaneously installing a gas heating mechanism and an electric heating mechanism in the steel melting furnace, the surface of the molten steel and the exposed scrap steel can be heated by gas combustion, while electromagnetic induction is used to heat the molten steel. Specifically, the gas burners provide concentrated heating to quickly break through the critical softening temperature of the scrap steel; then, targeted supplementary heating using electromagnetic induction achieves precise melting of the scrap steel. This significantly improves the overall heating and melting efficiency of the scrap steel and greatly reduces energy consumption. The device of this utility model also has the advantages of simple structure, low operating cost, and convenient and quick operation.

Description

Technical Field

[0001] This utility model relates to iron and steel smelting processes, specifically to a gas-electric co-operated steel melting device, belonging to the field of iron and steel smelting technology. Background Technology

[0002] Currently, there are two different processes in the steelmaking process: the converter long-process and the electric arc furnace short-process. The converter long-process primarily uses molten iron produced from ore and coke as raw material. It has a short smelting cycle, high production efficiency, and low cost per ton of steel. However, its drawback is that the production of molten iron involves sintering and pelletizing processes and blast furnace operations, resulting in high carbon emissions. The electric arc furnace short-process primarily uses recycled scrap steel after crushing and sorting. It does not involve other processes, resulting in lower carbon emissions and less environmental pollution. However, its drawbacks are a longer smelting cycle, lower production efficiency, and higher cost per ton of steel. Scrap steel is a cleaner resource compared to ore and can be infinitely recycled. Compared to using ore and coke to produce steel, using scrap steel can significantly reduce the emission of waste gas, wastewater, and slag.

[0003] Regardless of whether it's the electric arc furnace (EAF) short-process or the converter long-process, improving scrap steel utilization is increasingly valued by steel companies. For the long-process, increasing the scrap ratio can significantly reduce carbon emissions and improve resource utilization efficiency, thereby greatly reducing production costs. Increasing scrap preheating can further reduce production costs in the short-process, enhancing its competitiveness.

[0004] In existing technologies, the temperature of preheated scrap steel is generally far below its melting point. Therefore, it needs to be further heated in a steelmaking furnace until it melts into molten steel. The existing heating method of steelmaking furnaces is mainly gas combustion heating. Using burners to heat scrap steel, the temperature can be easily reached around 1000℃. However, if the temperature of scrap steel is to exceed 1000℃ and reach the melting point to melt the scrap steel into molten steel, it will lead to a significant increase in gas consumption, slow temperature rise, severe oxidation of scrap steel, and ineffective utilization of high-temperature flue gas. The energy utilization efficiency is low, the melting efficiency is low, and the melting cost will also be significantly increased. Utility Model Content

[0005] To address the shortcomings of existing technologies that rely solely on gas combustion to melt scrap steel, such as low melting efficiency and low energy utilization efficiency, this invention provides a gas-electric co-operated steel melting device. By simultaneously installing a gas heating mechanism and an electric heating mechanism in the steel melting furnace, after the scrap steel is partially melted into molten steel, the surface of the molten steel and the exposed scrap steel are heated by gas combustion, while electromagnetic induction is used to heat the molten steel. Combustion heating can rapidly raise the temperature of the scrap steel to about 1000°C. At this temperature, electromagnetic induction can efficiently transfer heat through the existing molten steel, thereby rapidly raising the temperature of the scrap steel to about 1500~1600°C and melting it into molten steel. In other words, this invention achieves rapid melting of scrap steel by coupling gas combustion with electric heating, while also significantly improving energy utilization efficiency.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by this utility model is as follows:

[0007] A gas-electric co-operated steel melting device includes a steel melting furnace, a gas heating mechanism, and an electric heating mechanism. The steel melting furnace includes a furnace shell and a furnace chamber, with a feeding channel connected to the furnace chamber at the upper part of the furnace shell. The gas heating mechanism is located at the upper part of the furnace chamber, and the electric heating mechanism is located at the lower part of the furnace chamber. A molten steel outlet is located at the bottom of the furnace chamber.

[0008] Preferably, the gas heating mechanism includes a burner and an inlet pipe. The combustion end of the burner extends into the furnace chamber after passing through the furnace shell near the feeding channel. The inlet end of the burner is connected to the inlet pipe, through which gas and auxiliary gas are supplied to the burner for combustion and heating. Preferably, a gas flow regulating valve is also provided on the inlet pipe.

[0009] Preferably, the electric heating mechanism is an electromagnetic induction coil, which is arranged around the furnace shell.

[0010] Preferably, a thermal imager is also installed at the top of the furnace cavity.

[0011] Preferably, the feeding channel is one of a horizontal channel, a vertical channel, or an inclined channel.

[0012] Preferably, the feeding channel is an inclined channel, and a partition is provided in the inclined channel to divide the inclined channel from top to bottom into a material storage area and a preheating area. A baffle is provided at the bottom of the preheating area, and a flue is provided at the top of the preheating area.

[0013] Preferably, thermocouples and pressure sensors are also installed in the flue gas outlet. A variable-speed fan is also connected to the flue gas exhaust port.

[0014] Preferably, one end of the partition passes through the top wall of the feeding channel and is connected to a lifting drive motor located externally. The lifting drive motor drives the partition to rise and fall, thereby realizing the opening and closing of the partition.

[0015] Preferably, a rotary drive motor connected to the retaining claw is also installed at the bottom of the preheating zone. The rotary drive motor drives the retaining claw to swing up and down in an arc (for example, the top of the retaining claw is hinged to the feeding channel through a bearing and a rotating shaft. Under the support of this hinge, the retaining claw can swing up and down in an arc. When the rotary drive motor drives the retaining claw to rotate upward, the retaining claw is opened, and the scrap steel can slide down along the feeding channel; when the rotary drive motor drives the retaining claw to rotate downward, the retaining claw is closed, and the scrap steel is blocked by the retaining claw). This realizes the opening and closing of the retaining claw.

[0016] Preferably, a cooling medium channel, a cooling medium inlet, and a cooling medium outlet connected to the cooling medium channel are also provided inside the material stop claw.

[0017] Preferably, the steel melting device also includes a controller, which is associated with and coordinates the working status of the gas heating mechanism, the thermocouple of the electric heating mechanism, the pressure sensor, the speed regulating fan, the lifting drive motor, the rotary drive motor, and the thermal imager.

[0018] The steps for melting steel using the gas-electric synergistic steel melting device of this invention include:

[0019] 1) Initial melting stage: Steel is added to the steel melting furnace, and the gas burner and / or electromagnetic induction heater are started to heat and melt the steel until molten steel is obtained.

[0020] 2) Continued melting stage: Steel is added to the melting furnace. Gas burners are used to heat the surface of the molten steel and the exposed steel on the surface of the molten steel. At the same time, electromagnetic induction heaters are used to heat the molten steel and the scrap steel submerged in the molten steel until the steel melts into molten steel and step 2 is repeated.

[0021] Preferably, the method further includes:

[0022] 3) Use the high-temperature flue gas generated in the steel melting furnace to preheat the steel to be melted in the furnace.

[0023] Preferably, the average temperature of the steel after preheating is not less than 300°C, and more preferably not less than 400°C.

[0024] Preferably, during the continuous melting stage, a power supply allocation model for gas and electricity under the target operating conditions is established with energy consumption cost as the independent variable. Based on this allocation model, the real-time power supply ratio of gas and electricity is calculated, thereby achieving steel melting at low cost. The power supply allocation model is as follows:

[0025] (I).

[0026] In equation (I), x is the ratio of energy supplied by natural gas to the total energy required under the target operating condition. gas This is the real-time unit price of gas, in yuan / m³. elec The real-time unit price of electricity is yuan / (kW·h). elec This represents the thermal efficiency of the electromagnetic induction heater. γ gas H represents the thermal efficiency of the gas burner. gas Let be the calorific value of the gas, in MJ / m³. The real-time energy supply ratio of gas under different energy consumption costs is calculated using equation (I), then the real-time energy supply ratio of electricity is (1-x).

[0027] Preferably, the real-time operating power of the gas burner is adjusted according to the real-time energy supply ratio of the gas to meet the operating conditions. Under the current operating conditions, the actual minimum operating power of a single gas burner should satisfy the following formula:

[0028] P gas =xMC(T obje -T0) / (ntγ gas (II).

[0029] In equation (II), P gas T represents the actual minimum operating power of a single gas burner, in MW. M is the mass of steel to be melted in the current steelmaking furnace, in kg. C is the specific heat capacity of the steel, in kJ / (kg·℃). obje Let T0 be the target melting temperature in the steelmaking furnace, in °C. T0 is the temperature of the steel entering the furnace, in °C. n is the number of gas burners activated. t is the steel melting cycle, in seconds. Under the current operating conditions, the minimum real-time operating power of a single gas burner is the calculated value P from equation (II). gas So that the real-time energy supply ratio of natural gas is x.

[0030] Preferably, the real-time operating power of the electromagnetic induction heater is adjusted according to the real-time power supply ratio demand to meet the requirements of the operating conditions. Under the current operating conditions, the actual minimum operating power of the electromagnetic induction heater should satisfy the following formula:

[0031] P elec =(1-x)MC(T obje -T0) / (tγ elec (III).

[0032] In equation (III), P elec T represents the actual minimum operating power of the electromagnetic induction heater, in MW. M is the mass of steel to be melted in the current steelmaking furnace, in kg. C is the specific heat capacity of the steel, in kJ / (kg·℃). obje T0 is the target melting temperature in the steel melting furnace, in °C. T0 is the temperature of the steel entering the furnace, in °C. t is the steel melting cycle, in seconds. Under the current operating conditions, the minimum real-time operating power of the electromagnetic induction heater is the calculated value P from equation (III). elec So that the real-time power supply ratio of electricity is (1-x).

[0033] As a preferred embodiment, the minimum operating power of a single gas burner when all the energy required for steel melting is supplied by gas is denoted as P. allgas When the calculated value x < 0.1, the actual minimum operating power P of a single gas burner is... gas =(0.05~0.15)P allgas .

[0034] Preferably, the minimum operating power of the electromagnetic induction heater when all the heat required for steel melting is supplied by electrical energy is denoted as P. allelec When the calculated value (1-x) < 0.05, the actual minimum operating power P of the electromagnetic induction heater is... elec =(0.05~0.1)P allelec Preferably, when the calculated value (1-x) < 0.05, P elec The value ranges from 40,000 to 60,000W, for example, 50,000W.

[0035] In existing technologies, using only a burner to preheat and melt scrap steel can relatively easily achieve a preheating temperature of around 1000℃, resulting in lower overall costs. However, to melt the scrap steel into molten steel at 1500-1600℃, the gas consumption increases significantly, the temperature rise is slow, scrap steel oxidation is severe, and the high-temperature flue gas cannot be effectively utilized, leading to low energy efficiency and high costs. While using electromagnetic induction heating alone for preheating and melting scrap steel offers high energy efficiency, at lower scrap steel temperatures (below 800℃), the heating rate is slow, power consumption is high, and heating costs are high. Therefore, this invention couples gas burner heating and electromagnetic induction heating. Gas combustion rapidly raises the temperature of the molten steel surface and exposed scrap steel, while electromagnetic induction further increases the temperature of the liquid below the molten steel surface and the scrap steel, thus achieving efficient and rapid melting of the scrap steel. In other words, during the process of heating and melting scrap steel, the scrap steel temperature is raised to above 800°C in a low-cost and rapid manner by using gas combustion. Then, electromagnetic induction is used to further heat and melt the scrap steel. When the scrap steel temperature exceeds its melting point and becomes liquid, the overall thermal efficiency of electromagnetic induction heating will be further improved due to the electromagnetic stirring effect (heat transfer efficiency is increased by 15~20%), and the melting efficiency will be further improved, while the cost can be reduced again.

[0036] In this utility model, the steel melting device provided is mainly a steel melting furnace, which includes a furnace shell and a furnace chamber. Inside the furnace chamber, there are gas-fired heating burners (i.e., gas heating mechanisms, such as gas burners) for rapidly heating scrap steel and electromagnetic heaters (i.e., electric heating mechanisms, such as electromagnetic induction coils) for rapidly melting the scrap steel. The gas burners are used to rapidly heat the scrap steel entering the furnace chamber (especially scrap steel piled above molten steel; in continuous production, a certain amount of molten steel is generally reserved in the furnace chamber). They adopt a preheating structure, including a combustion air jacket and a gas jacket. A tubular heat exchanger can be installed at the front end of the combustion air jacket to preheat the combustion air using high-temperature flue gas, saving energy. Generally, one gas-fired heating burner is arranged on each side of the scrap steel landing area inside the furnace chamber, and the burners have a certain horizontal and vertical deflection angle. Electromagnetic induction coils are primarily used to rapidly melt scrap steel submerged in molten steel. They utilize electromagnetic induction to heat the molten steel, and the scrap steel melts quickly through heat transfer from the molten steel. The alternating magnetic field generated by electromagnetic induction induces a current in the molten steel, which in turn generates heat through the steel's resistance, thus heating both the molten steel and the scrap steel. In other words, when preheated scrap steel enters the melting furnace, it accumulates below the gas burner, with the scrap steel at higher preheating temperatures at the bottom and the scrap steel at lower preheating temperatures at the top. Under the "steel retention" operation, the high-temperature scrap steel at the bottom enters the melting furnace, and the electromagnetic induction heater uses the molten steel to transfer heat to the scrap steel, achieving rapid melting. The purpose of steel retention is that the molten steel is in a liquid state, and under the influence of electromagnetic force, it rotates and flows, allowing heat to be transferred more quickly to the scrap steel submerged in the molten steel, accelerating its heating and melting. However, the low-temperature scrap steel accumulated at the top, which does not come into contact with the molten steel, heats up slowly solely through electromagnetic induction. At this point, the gas burner is turned on, and the heat generated by the combustion of natural gas is used to quickly preheat the low-temperature scrap steel above the molten steel, or even locally heat it to directly melt the scrap steel, allowing the scrap steel to be immersed in the molten steel more quickly. This greatly reduces the heating time of the scrap steel.

[0037] In this invention, the molten steel furnace adopts a non-tilting tapping method, which facilitates continuous production. The molten steel outlet is designed as a stepped structure. During normal steel retention, the molten steel height is lower than the height of the tapping step. During tapping, a ladle is placed below the molten steel outlet, and acetylene is used to burn through the outlet, allowing the molten steel to flow into the ladle. Tapping stops when the molten steel height is lower than the tapping step height, and the outlet is blocked with diversion sand. The tapping step has a certain height (designed according to actual operating conditions).

[0038] In this invention, the melting of scrap steel generates a large amount of high-temperature flue gas (around 1200°C). This flue gas contains a significant amount of waste heat, which can be used to preheat the scrap steel, thereby increasing the temperature of the scrap steel entering the furnace, improving melting efficiency, and reducing melting energy consumption. Therefore, the steel melting method of this invention also includes a step of preheating the steel to be melted using the high-temperature flue gas generated in the steel melting furnace. Similarly, the steel melting device of this invention also includes a feeding and preheating channel for adding scrap steel to the steel melting furnace and preheating it. This feeding and preheating channel is divided into an upper storage area and a lower preheating area by a partition. A baffle is provided at the connection between the lower preheating area and the furnace chamber, and a flue gas outlet is provided at the upper end of the lower preheating area. The upper storage area and the lower preheating area are connected and isolated by the raising and lowering of the baffle plate. This allows scrap steel temporarily stored in the upper storage area to enter the lower preheating area. The lowering and closing of the baffle claw allows the scrap steel to remain in the lower preheating area. At the same time, high-temperature flue gas from the furnace enters the lower preheating area and exchanges heat with the scrap steel in a countercurrent manner before being discharged from the flue gas outlet. Then, the baffle claw is raised and opened to allow the preheated scrap steel to enter the furnace for melting. In other words, by integrating the three steps of scrap steel storage, preheating, and melting, continuous production of scrap steel melting is achieved.

[0039] Furthermore, flue gas temperature and pressure detectors (such as thermocouples and pressure sensors) are installed at the flue gas outlet to monitor the temperature of the exhaust gas and the pressure at the outlet in real time. Based on the changes in flue gas temperature at the outlet, the utilization efficiency of waste heat and the preheating effect of the scrap steel can be predicted and judged. The preheating temperature of scrap steel is related to many factors, making prediction and control difficult. The following analysis examines the influence of various factors on the preheating temperature of scrap steel: First, the inclination angle α of the feeding and preheating channels affects the state of the scrap steel in the channels, thus affecting the contact area A between the scrap steel and the flue gas. The contact area A can be expressed as A = A0(1 + k A α), where k A The contact area influence coefficient (an empirical value, generally taken as 0.01~0.1), where A0 is the contact area in the horizontal state. Secondly, the distance d between the baffle claws and the negative pressure P at the smoke outlet are also considered. out Affecting flue gas velocity v g This, in turn, affects heat transfer, and the combined effect of both factors leads to the flue gas velocity v. g It can be represented as Where k3 is the flue gas velocity influence coefficient (empirical value, generally taken as 0.8~2.0), γ is the flue gas resistance coefficient, and ρ g The density of the flue gas is [value missing]. The steelmaking furnace operates under slight negative pressure, with the preferred negative pressure being P. out The pressure is controlled within the range of 0 to -100 Pa. It is also affected by the outlet flue gas temperature T. out Inlet flue gas temperature T inImpact: Under stable operating conditions of the steelmaking furnace, the inlet flue gas temperature T can be considered as... in The temperature remains constant, generally considered to be up to 1200℃; the outlet flue gas temperature T out Changes are monitored in real time by a temperature monitoring device at the flue gas outlet. The outlet flue gas temperature must not be too high, as excessively high outlet flue gas temperatures will lead to low heat utilization efficiency; it is generally controlled within a certain range (T). out -T obj ≤50℃ is recommended (T) obj (This refers to the target preheating temperature for scrap steel). Furthermore, according to heat balance, within a certain time t, the heat absorbed by the scrap steel is equal to the heat transferred to the scrap steel by the flue gas. Therefore, the scrap steel preheating temperature T... s (Assuming the scrap steel temperature is uniform, the average scrap steel temperature is used instead.) The calculation formula is as follows:

[0040] =

[0041] Therefore, we can conclude that:

[0042] .

[0043] In the above formula, k3 is the influence coefficient of flue gas velocity, with a value ranging from 0.8 to 2.0. h is the heat transfer coefficient between scrap steel and flue gas, with a value ranging from 15 to 80 W / (m³). 2 ·K). d is the distance between two adjacent stop claws, in cm. P out ρ represents the negative pressure at the flue gas outlet, in Pa. γ is the flue gas resistance coefficient. g The density of the flue gas is expressed in g / cm³. 3 D is the diameter of the smoke outlet, in cm. C p T represents the specific heat capacity of the flue gas, in J / (kg·K). t is the duration of the unit time period, ranging from 60 to 600 seconds. in T represents the initial temperature of the flue gas, in °C. out The temperature of the flue gas at the outlet is ℃. s The weight of the steel is expressed in kg. (C) s T represents the specific heat capacity of steel, in J / (kg·K). s,i T represents the temperature of the scrap steel at the current time point, in °C. s,i+1 Let T be the temperature of the scrap steel after the current time period, in °C (where i is an integer greater than or equal to 0, and T is a constant). s,0 (These are measured values, ranging from 10 to 30℃). The real-time preheating temperature of the steel can be calculated using the above formula after different time periods. The specific preheating temperature control process for scrap steel is as follows:

[0044] Step 1: Input the parameters, mainly including: the inclination angle α of the feeding and preheating channels, the distance d between the baffle claws, the heat transfer coefficient h between scrap steel and flue gas, the contact area A0 between scrap steel and flue gas, and the mass m of scrap steel.s Specific heat capacity of scrap steel C s D, the diameter of the flue outlet; C, the specific heat capacity of the flue gas. p Steel size influence coefficient k1, flue gas velocity influence coefficient k3, flue gas resistance coefficient γ, flue gas density ρ g Adjust the pressure difference ΔP = 10 Pa, the time interval Δt = 60 s, and the inlet flue gas temperature T. in =1200℃, initial temperature of scrap steel T s,0 =25℃.

[0045] Step 2: Based on the monitoring equipment, obtain the outlet negative pressure P after a time interval Δt = 60s. out , outlet flue gas temperature T out Calculate the preheating temperature T of the scrap steel. s,i And calculate the difference between the preheating temperature of the scrap steel and the target preheating temperature at this time, i.e., ΔT = T s,it -T obj .

[0046] Step 3: If ΔT ≤ 0, meaning the average temperature of the scrap steel is lower than the target value, heating is required. At this point, first determine if the outlet flue gas temperature exceeds the target to avoid heat loss. If T... out -T obj ≤50℃ indicates that the outlet flue gas temperature is not excessive. At this time, adjust the power of the outlet fan to increase the outlet negative pressure, i.e., P. out,i+1 =P out,i -△P. Increased flue gas flow rate leads to increased heat transferred to the scrap steel within a certain timeframe, which is beneficial for the scrap steel's heating. It should be noted that to maintain low negative pressure operation, if the negative pressure P... out,i+1 If ≤-100Pa, then take P. out,i+1 =-100Pa; if T out -T obj A temperature >50℃ indicates that the outlet flue gas temperature is too high. In this case, adjust the fan power to reduce the outlet negative pressure, i.e., P. out,i+1 =P out,i +△P. With reduced flue gas flow, the outlet flue gas temperature naturally decreases after heat absorption by the scrap steel. Similarly, to maintain a slight negative pressure operation, if P... out,i+1 If >0Pa, then take P. out,i+1 =-10Pa.

[0047] Step 4: If ΔT > 0, meaning the average temperature of the scrap steel has reached the target value, only heat preservation is needed; the preheated scrap steel can be added to the melting furnace at any time. At this point, set P... out,i+1 =-10Pa and remain stable until the preheating of the scrap steel in that heat is completed. It should be noted that the values ​​in the above statement are merely exemplary values ​​for the purpose of illustrating the technical solution, and are not intended to limit the technical solution claimed by this utility model.

[0048] In existing technologies, traditional preheating devices mostly adopt simple horizontal or vertical structures, which have many shortcomings in material conveying. For example, in horizontal preheating devices, scrap steel is conveyed by mechanical propulsion, resulting in slow start-up and shutdown responses, making it difficult to accurately control the feeding amount and time interval, often leading to over- or under-feeding. In this invention, a feeding and preheating channel with a certain inclination angle is preferred for feeding the steelmaking furnace and preheating the scrap steel. The inclined feeding and preheating channel, by adjusting the inclination angle, cleverly utilizes gravity as the driving force for conveying different types of scrap steel. It can slide down at a stable speed under the action of gravity, ensuring that the amount of scrap steel conveyed each time is accurately controllable, effectively solving the problem of difficult control of the material conveying rhythm in traditional devices. Compared with the mechanically driven feeding method of traditional horizontal preheating devices, the feeding efficiency of the inclined feeding and preheating channel is increased by 30-50%, greatly shortening the feeding time and improving the overall production efficiency. Furthermore, when high-temperature flue gas is used to preheat scrap steel in the inclined feeding and preheating channel, the contact area and contact time with the flue gas are greatly increased, and the utilization efficiency of heat in the flue gas and the preheating temperature of the scrap steel are significantly improved.

[0049] In this invention, when the inclined feeding and preheating channel is used to feed and preheat scrap steel, the scrap steel will slide downwards continuously under its own gravity. The length of the inclined feeding and preheating channel is generally fixed, meaning that the time it takes for the scrap steel to slide through the inclined feeding and preheating channel is generally relatively short. During this process, it is difficult to preheat the scrap steel to the target temperature. At the same time, it also takes a certain amount of time for the scrap steel in the steel melting furnace to melt into molten steel. Therefore, it is impossible to continuously add scrap steel through the inclined feeding and preheating channel indefinitely. Therefore, an intermittent addition method is generally adopted. That is, by setting a baffle claw at the bottom of the inclined feeding and preheating channel, the scrap steel is left in the inclined feeding and preheating channel for a certain period of time. After the scrap steel is preheated to the target temperature, the baffle claw is opened to slide the preheated scrap steel into the steel melting furnace. At this time, the previous batch of scrap steel in the steel melting furnace has also basically melted into molten steel.

[0050] It should be noted that in this invention, the inclined feeding and preheating channel is typically made of a high-temperature resistant and wear-resistant alloy material, capable of withstanding the erosion of high-temperature flue gas and the friction during scrap steel sliding. As the main channel for scrap steel sliding and heat exchange with high-temperature flue gas, the inclined feeding and preheating channel utilizes gravity to allow the scrap steel to slide naturally, reducing additional power consumption and greatly improving feeding efficiency. Simultaneously, the inclined design increases the contact time and area between the scrap steel and the high-temperature flue gas, which is beneficial for improving heat exchange efficiency. Furthermore, to better utilize the waste heat from the scrap steel, the inclination angle α of the inclined feeding and preheating channel is not fixed but closely related to the characteristics of the scrap steel to be processed. That is, the inclination angle of the inclined feeding and preheating channel will vary accordingly for different types of scrap steel. Determining the optimal inclination angle α is crucial for improving the preheating effect of the scrap steel. Different types of scrap steel differ in size, density, porosity, etc., and these factors affect the sliding characteristics of the scrap steel, the force on the baffle claws, and the permeability and heat exchange efficiency of the flue gas. Therefore, determining the optimal tilt angle α requires comprehensive consideration of factors such as the scrap steel sliding speed and the force on the stop claw. Assuming the average length of the scrap steel is l0 (unit: m), the average width is w0 (unit: m), and the average thickness is h0 (unit: m), the equation of motion for the sliding speed v (unit: m / s) of scrap steel of different sizes is as follows:

[0051] (1-1).

[0052] In equation (1-1), g is the acceleration due to gravity, which is generally taken as 9.8 m / s². 2 μ is the friction coefficient between the scrap steel and the feeding and preheating channels, with a value of 0.2~0.6. k1 is the influence coefficient of steel size, with a value of 0.1~5.0. That is to say, the magnitude of the sliding speed of the scrap steel at different inclination angles can be calculated according to equation (1-1).

[0053] Once the downward velocity v of the scrap steel is known, the impact force F (in N) on the retaining claw when the scrap steel comes into contact with the retaining claw can be calculated using the following formula:

[0054] (1-2).

[0055] In equation (1-2), m s The mass of the steel is expressed in kg (generally, the mass of steel can be obtained by weighing, or it can be calculated: m). s =ρl0w0h0, where ρ is the density of steel, kg / m³ 3△t is the collision time between the steel and the stop claw (an empirical estimate, generally taken as 0.01~1s), s. k2 is the force coefficient of the stop mechanism, with a value of 10~100. That is to say, according to formula (1-2), the magnitude of the impact force on the stop claw of the ventilated stop mechanism at different sliding speeds can be calculated.

[0056] To determine the optimal tilt angle α, a comprehensive evaluation factor E is introduced:

[0057] (1-3).

[0058] In equation (III), v smax F represents the maximum permissible downward sliding speed of the steel under the operating conditions, in m / s. max The maximum load-bearing capacity (N) of the permeable material stop mechanism (101) under the permitted working conditions is given by S = (l0 + w0 + h0) / (l0w0h0). opt The optimal comprehensive parameters for steel dimensions under ideal production conditions are taken as 5~50. v As the weight of factors affecting the rate of decline in steel prices, w F The weights of the factors affecting the force on the stop claw, w S The weights of the steel size factor, where: w v +w F +w s =1, w v w F w s All are greater than 0 and less than 1. That is to say, the comprehensive evaluation factor value corresponding to different tilt angles α is calculated according to formula (1-3). The α value corresponding to the comprehensive evaluation factor reaching its maximum value is the tilt angle of the tilted feeding and preheating channel under the current working condition. The steps to obtain the comprehensive evaluation factor reaching its maximum value are as follows: Set the tilt angle adjustment range of the tilted feeding and preheating channel to 30~60°. First, give an initial tilt angle of 30°, then α1=0.524 (30° converted to radians is 0.524). Then, according to the above formulas (1-1) and (1-2), calculate the v corresponding to α1=0.524 respectively. s1 And F1, and then calculate the corresponding E1 according to formula (1-3). Finally, increase the tilt angle by a certain step (such as 0.01 radians) to get α2=α1+0.01, and then calculate v corresponding to α2=α1+0.01=0.524+0.01 according to formulas (1-1), (1-2), and (1-3) respectively. s2 F2 and E2; repeat the above process until all comprehensive evaluation factor E values ​​corresponding to the entire tilt angle range of 30~60° (0.524~1.047 radians) are traversed. Then compare all the calculated E values ​​and find the tilt angle α that maximizes E.b , this α b This refers to the angle of inclination of the inclined feeding and preheating channel under the current optimal conditions for steel.

[0059] In this invention, the smelting of scrap steel utilizes both natural gas and electricity. Compared to using a single energy source, this method is largely unaffected by fluctuations in market energy prices or by climate change (primarily electricity prices). This effectively avoids the constraint of having to use a single energy source at high costs to maintain production when the price of that energy increases. Furthermore, this invention, through the integrated gas-electric synergistic smelting process, can coordinate the allocation of both energy sources based on price fluctuations, minimizing unit production costs while meeting scrap steel smelting requirements and significantly improving economic efficiency.

[0060] In this invention, to maximize the benefits of integrated gas-electric smelting, the burner power and electromagnetic induction power need to be adjusted in real time according to energy prices during the scrap steel smelting process, thereby reducing total energy consumption. Therefore, the first step is to determine the total energy required to heat a certain weight of scrap steel (single feed amount or single furnace feed amount) to a certain temperature: let the total energy requirement be Q. total Then, each ton of scrap steel is smelted to temperature T. obje The required energy is Q = C × ΔT, where ΔT = T obje -T0, where T0 is the initial temperature of the scrap steel entering the furnace (generally the temperature of the scrap steel after efficient preheating by process flue gas before entering the steelmaking furnace). If the capacity of the steelmaking furnace A is M tons, then the total energy requirement is Q. total =M×Q=M×C×(T obje -T0). Then ensure that the energy supply meets Q. total Under the premise of dynamically adjusting the ratio of gas and electricity use according to fluctuating energy prices, assuming the use of natural gas burners (taking two units as an example), the smelting cycle t a Let t1 be the thermal efficiency γ. gas The calorific value of natural gas is H. gas Then the power P of a single burner gas ≥Q total / (2t1γ gas ), where P gas Rounded down, including redundancy. Assume the melting cycle of an electromagnetic induction system (taking one system as an example) is t. a Given t2, the electrothermal efficiency of the electromagnetic induction system is γ. elec Then the power of the electromagnetic induction system is P. elec ≥Q total / (t2γ elec ), where P elecThe value is rounded down, including redundancy. Therefore, during real-time adjustments, the total smelting cost is minimized by dynamically adjusting the ratio of natural gas to electricity usage and leveraging the price fluctuations of both.

[0061] (i) Total energy demand Q total Proportional allocation to natural gas and electricity: Q total =Q gas +Q elec ; where Q gas =xQ total Q elec =(1-x)Q total , where x is the proportion of energy sharing from natural gas.

[0062] (ii) Set the real-time natural gas unit price to S gas The real-time electricity price is S elec Then we have: Total cost = Q gas S gas / (γ gas H gas )+Q elec S elec / γ elec Substitute Q gas and Q elec Then we have:

[0063] Total cost = Q total [xS gas / (γ gas H gas )+(1-x)S elec / 3.6γ elec ].

[0064] (iii) Differentiate the total cost function and set the derivative to zero to solve for x:

[0065] .

[0066] , .

[0067] By combining the two energy sources, we can obtain an energy supply and distribution model:

[0068] (I).

[0069] In equation (I), x is the ratio of energy supplied by natural gas to the total energy required under the target operating condition. gas This is the real-time unit price of gas, in yuan / m³. elec The real-time unit price of electricity is yuan / (kW·h). elec This represents the thermal efficiency of the electromagnetic induction heater. γ gas H represents the thermal efficiency of the gas burner.gas Let be the calorific value of the gas, in MJ / m³. The real-time energy supply ratio of gas under different energy consumption costs is calculated using equation (I), then the real-time energy supply ratio of electricity is (1-x). The ratio x is determined by the current energy price: when the natural gas price is low, increase the burner power; when the electricity price is low, increase the electromagnetic induction power.

[0070] (iv) Adjusting the energy supply ratio of gas and electricity is mainly achieved by adjusting the real-time operating power of the gas burner and the electromagnetic induction heater:

[0071] The real-time operating power of the gas burner is adjusted according to the real-time energy supply ratio demand of the gas to meet the requirements of the operating conditions. Under the current operating conditions, the actual minimum operating power of a single gas burner should satisfy the following formula:

[0072] P gas =xMC(T obje -T0) / (ntγ gas (II).

[0073] In equation (II), P gas T represents the actual minimum operating power of a single gas burner, in MW. M is the mass of steel to be melted in the current steelmaking furnace, in kg. C is the specific heat capacity of the steel, in kJ / (kg·℃). obje Let T0 be the target melting temperature in the steelmaking furnace, in °C. T0 is the temperature of the steel entering the furnace, in °C. n is the number of gas burners activated. t is the steel melting cycle, in seconds. Under the current operating conditions, the minimum real-time operating power of a single gas burner is the calculated value P from equation (II). gas So that the real-time energy supply ratio of natural gas is x.

[0074] The real-time operating power of the electromagnetic induction heater is adjusted according to the real-time energy supply ratio demand to meet the requirements of the operating conditions. Under the current operating conditions, the actual minimum operating power of the electromagnetic induction heater should satisfy the following formula:

[0075] P elec =(1-x)MC(T obje -T0) / (tγ elec (III).

[0076] In equation (III), P elec T represents the actual minimum operating power of the electromagnetic induction heater, in MW. M is the mass of steel to be melted in the current steelmaking furnace, in kg. C is the specific heat capacity of the steel, in kJ / (kg·℃). obje T0 is the target melting temperature in the steel melting furnace, in °C. T0 is the temperature of the steel entering the furnace, in °C. t is the steel melting cycle, in seconds. Under the current operating conditions, the minimum real-time operating power of the electromagnetic induction heater is the calculated value P from equation (III).elec So that the real-time power supply ratio of electricity is (1-x).

[0077] In this invention, the real-time functional process of adjusting the gas burner and electromagnetic sensor is roughly as follows: First, real-time data input: Real-time update and input of the natural gas price S. gas and electricity price elec Then calculate the optimal ratio: dynamically calculate the ratio of natural gas to electricity usage x and (1-x) according to formula (I). Finally, implement the strategy: when the electricity price is low, decrease x and increase the electricity usage ratio (1-x); when the natural gas price is low, increase x and increase the natural gas usage ratio (1-x). Specific adjustment: the adjustment of the gas burner is mainly achieved by continuously adjusting the gas flow through a proportional valve to achieve precise control of the total power; if the adjusted gas power supply ratio x i If the value is less than 0.1, then the actual working power P of the two gas burners after adjustment is... gas1-i =P gas2-i =0.1P allgass (P) allgas This refers to the minimum operating power of a single gas burner when all the energy required for steel melting is supplied by gas, to prevent flameout or unstable combustion. If x i If P ≥ 0.1, then P gas1-i =P gas2-i =x i P allgass The adjustment of the electromagnetic induction system mainly involves dynamically adjusting its actual operating power according to electricity price fluctuations while maintaining basic operation. If the adjusted actual energy supply ratio (1-x) i If ≥ 0.05, then the actual operating power P of the electromagnetic induction system after adjustment elec-i =(1-xi)P allelec (P) allelec (where the minimum operating power of the electromagnetic induction heater is the power required for all the energy needed to melt steel is supplied by electricity), if (1-x i If ) < 0.05, then P elec-i =(0.05~0.1)P allelec =40~60kW, which puts the electromagnetic induction system into standby mode to avoid a complete shutdown.

[0078] It should be noted that all formulas in this utility model are obtained by the inventor based on experiments and engineering applications, and all calculations are obtained by converting values ​​according to the specified units and substituting the converted values ​​into the formulas (after converting the units, only the values ​​are substituted into the formulas for calculation, not the units; the units are only used to adjust the size of the values).

[0079] In this invention, the number of gas heating mechanisms is 1-20, preferably 2-30, and more preferably 3-20. The thickness of the furnace shell is 1-300 cm, preferably 5-200 cm, and more preferably 10-100 cm. The volume of the furnace chamber is 0.3-100 m³. 3 Preferably, the depth is 0.5~50m 3 More preferably 0.8~30m 3 .

[0080] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0081] 1. This utility model breaks through the traditional single energy dependence mode. By coupling and coordinating natural gas burners (rapid heating) and electromagnetic induction (precise melting), the critical temperature for softening scrap steel is broken through in a short time through centralized heating of gas burners; then, electromagnetic induction is used to target and supplement heating to achieve precise melting of scrap steel, which greatly improves the overall heating and melting efficiency of scrap steel and greatly reduces energy consumption.

[0082] 2: This utility model also combines rapid heating of the gas burner with precise melting coupling of the electromagnetic inductor, and also incorporates waste heat recovery of flue gas to efficiently preheat scrap steel, realizing the cascade utilization of energy. The combustion flue gas of the burner can efficiently preheat scrap steel to above 400°C, further reducing the energy consumption and time of subsequent melting. Attached Figure Description

[0083] Figure 1 This is a schematic diagram of the steel melting furnace of this utility model.

[0084] Figure 2 This is a schematic diagram of the structure of the steel melting furnace of this utility model when it has an inclined feeding channel.

[0085] Figure 3 This is a schematic diagram of the material stop claw of this utility model.

[0086] Attached markings: 1: Steel melting furnace; 101: Furnace shell; 102: Furnace chamber; 103: Molten steel outlet; 2: Gas heating mechanism; 201: Burner; 202: Gas inlet pipe; 203: Gas flow regulating valve; 3: Electric heating mechanism; 4: Feeding channel; 401: Baffle; 402: Material storage area; 403: Preheating zone; 404: Material retainer; 4041: Cooling medium channel; 4042: Cooling medium inlet; 4043: Cooling medium outlet; 405: Flue; 406: Thermocouple; 407: Pressure sensor; 408: Speed ​​regulating fan; 409: Lifting drive motor; 410: Rotation drive motor; 5: Thermal imager. Detailed Implementation

[0087] The technical solution of this utility model is illustrated below. The scope of protection of this utility model includes, but is not limited to, the following embodiments.

[0088] A gas-electric co-operated steel melting device includes a steel melting furnace 1, a gas heating mechanism 2, and an electric heating mechanism 3. The steel melting furnace 1 includes a furnace shell 101 and a furnace chamber 102, with a feeding channel 4 connected to the furnace chamber 102 at the upper part of the furnace shell 101. The gas heating mechanism 2 is located at the upper part of the furnace chamber 102, and the electric heating mechanism 3 is located at the lower part of the furnace chamber 102. A molten steel outlet 103 is located at the bottom of the furnace chamber 102.

[0089] Preferably, the gas heating mechanism 2 includes a burner 201 and an air inlet pipe 202. The combustion end of the burner 201 extends into the furnace chamber 102 after passing through the furnace shell 101 near the feeding channel 4. The air inlet end of the burner 201 is connected to the air inlet pipe 202, through which gas and auxiliary gas are supplied to the burner 201 for combustion and heating. Preferably, a gas flow regulating valve 203 is also provided on the air inlet pipe 202.

[0090] Preferably, the electric heating mechanism 3 is an electromagnetic induction coil, which is arranged around the furnace shell 101.

[0091] Preferably, a thermal imager 5 is also installed at the top of the inner cavity of the furnace 102.

[0092] Preferably, the feeding channel 4 is one of a horizontal channel, a vertical channel, or an inclined channel.

[0093] Preferably, the feeding channel 4 is an inclined channel, in which a partition 401 is provided to divide the inclined channel from top to bottom into a storage area 402 and a preheating area 403. A baffle 404 is provided at the bottom of the preheating area 403, and a flue duct 405 is also provided at the top of the preheating area 403.

[0094] Preferably, a thermocouple 406 and a pressure sensor 407 are also installed in the flue gas outlet 405. The flue gas outlet 405 is also connected to a speed-regulating fan 408.

[0095] Preferably, one end of the partition 401 passes through the top wall of the feeding channel 4 and is connected to a lifting drive motor 409 located on the outside. The lifting drive motor 409 drives the partition 401 to rise and fall, thereby realizing the opening and closing of the partition 401.

[0096] Preferably, a rotary drive motor 410 connected to the baffle 404 is also provided at the bottom of the preheating zone 403. The rotary drive motor 410 drives the baffle 404 to swing and lower in an arc-like manner, thereby realizing the opening and closing of the baffle 404.

[0097] Preferably, a cooling medium channel 4041, a cooling medium inlet 4042, and a cooling medium outlet 4043 connected to the cooling medium channel 4041 are also provided inside the material stop claw 404.

[0098] Example 1

[0099] like Figure 1-3 As shown, a gas-electric co-operated steel melting device includes a steel melting furnace 1, a gas heating mechanism 2, and an electric heating mechanism 3. The steel melting furnace 1 includes a furnace shell 101 and a furnace chamber 102, with a feeding channel 4 connected to the furnace chamber 102 at the upper part of the furnace shell 101. The gas heating mechanism 2 is located at the upper part of the furnace chamber 102, and the electric heating mechanism 3 is located at the lower part of the furnace chamber 102. A molten steel outlet 103 is located at the bottom of the furnace chamber 102.

[0100] Example 2

[0101] The embodiment 1 is repeated, except that the gas heating mechanism 2 includes a burner 201 and an air inlet pipe 202. The combustion end of the burner 201 extends into the furnace chamber 102 after passing through the furnace shell 101 near the feeding channel 4. The air inlet end of the burner 201 is connected to the air inlet pipe 202, through which gas and auxiliary gas are supplied to the burner 201 for combustion and heating.

[0102] Example 3

[0103] The same as embodiment 2 is repeated, except that a gas flow regulating valve 203 is also provided on the air intake pipe 202.

[0104] Example 4

[0105] Example 3 is repeated, except that the electric heating mechanism 3 is an electromagnetic induction coil, which is arranged in a ring around the furnace shell 101.

[0106] Example 5

[0107] The embodiment 4 is repeated, except that a thermal imager 5 is also installed at the top of the inner cavity of the furnace 102.

[0108] Example 6

[0109] Repeat Example 5, except that the feeding channel 4 is a horizontal channel.

[0110] Example 7

[0111] Repeat Example 5, except that the feeding channel 4 is a vertical channel.

[0112] Example 8

[0113] Example 5 is repeated, except that the feeding channel 4 is an inclined channel, and a partition 401 is provided in the inclined channel to divide the inclined channel from top to bottom into a storage area 402 and a preheating area 403. A baffle 404 is provided at the bottom of the preheating area 403, and a flue duct 405 is also provided at the top of the preheating area 403.

[0114] Example 9

[0115] The embodiment 8 is repeated, except that a thermocouple 406 and a pressure sensor 407 are also provided in the flue duct 405. The flue outlet of the flue duct 405 is also connected to a speed-regulating fan 408.

[0116] Example 10

[0117] Repeat embodiment 9, except that one end of the partition 401 passes through the top wall of the feeding channel 4 and is connected to the lifting drive motor 409 located on the outside. The lifting drive motor 409 drives the partition 401 to rise and fall, thereby realizing the opening and closing of the partition 401.

[0118] Example 11

[0119] Repeat embodiment 10, except that a rotary drive motor 410 connected to the baffle 404 is also provided at the bottom of the preheating zone 403. The rotary drive motor 410 drives the baffle 404 to swing and lower in an arc, thereby realizing the opening and closing of the baffle 404.

[0120] Example 12

[0121] The embodiment 11 is repeated, except that a cooling medium channel 4041, a cooling medium inlet 4042, and a cooling medium outlet 4043 connected to the cooling medium channel 4041 are also provided inside the material stop claw 404.

[0122] When using this utility model: First, open the baffle claw 404 to send the preheated scrap steel into the furnace chamber 102 of the steel melting furnace 1. Then, close the baffle claw 404 and open the baffle 401 to add scrap steel to the preheating zone 403 again. After that, close the baffle 401 and continue to add scrap steel to the storage zone 402 for temporary storage. At the same time, start the gas heating mechanism 2 and the electric heating mechanism 3 (electromagnetic inductor) to melt the scrap steel. After all the scrap steel has melted, open the molten steel outlet 103 to discharge some molten steel (i.e., leave a certain amount of molten steel in the steel melting furnace 1). Then, close the molten steel outlet 103, open the baffle claw 404 again to send the preheated scrap steel into the furnace chamber 102 of the steel melting furnace 1. Then, close the baffle claw 404 and open the baffle 401 to add scrap steel to the preheating zone 403 again. After that, close the baffle 401 and continue to add scrap steel to the storage zone 402 for temporary storage. By repeating the above process, the smelting of scrap steel can be continuously achieved.

Claims

1. A gas-electricity synergistic steel material melting device, characterized by: The steel melting device includes a steel melting furnace (1), a gas heating mechanism (2), and an electric heating mechanism (3); the steel melting furnace (1) includes a furnace shell (101) and a furnace chamber (102), and a feeding channel (4) connected to the furnace chamber (102) is provided on the upper part of the furnace shell (101); the gas heating mechanism (2) is located on the upper part of the furnace chamber (102), and the electric heating mechanism (3) is located on the lower part of the furnace chamber (102); a molten steel outlet (103) is provided at the bottom of the furnace chamber (102).

2. The steel melting apparatus according to claim 1, characterized in that: The gas heating mechanism (2) includes a burner (201) and an air inlet pipe (202); the combustion end of the burner (201) extends into the furnace chamber (102) after passing through the furnace shell (101) near the feeding channel (4); the air inlet end of the burner (201) is connected to the air inlet pipe (202), and gas and auxiliary gas are delivered to the burner (201) through the air inlet pipe (202) for combustion and heating.

3. The steel melting apparatus according to claim 2, characterized in that: A gas flow regulating valve (203) is also installed on the air intake pipe (202).

4. The steel melting apparatus according to claim 1, characterized in that: The electric heating mechanism (3) is an electromagnetic induction coil, which is arranged around the furnace shell (101).

5. The steel melting apparatus according to claim 1, characterized in that: A thermal imager (5) is also installed at the top of the inner cavity of the furnace (102).

6. The steel melting apparatus according to any one of claims 1-5, characterized in that: The feeding channel (4) is one of the following: horizontal channel, vertical channel, or inclined channel.

7. The steel melting apparatus according to claim 6, characterized in that: The feeding channel (4) is an inclined channel. A partition (401) is provided in the inclined channel to divide the inclined channel into a storage area (402) and a preheating area (403) from top to bottom. A baffle claw (404) is provided at the bottom of the preheating area (403), and a flue (405) is also provided at the top of the preheating area (403).

8. The steel melting apparatus according to claim 7, characterized in that: A thermocouple (406) and a pressure sensor (407) are also installed in the flue (405); the flue outlet of the flue (405) is also connected to a speed-regulating fan (408).

9. The steel melting apparatus according to claim 8, characterized in that: One end of the partition (401) passes through the top wall of the feeding channel (4) and is connected to the lifting drive motor (409) located outside. The lifting drive motor (409) drives the partition (401) to rise and fall, thereby realizing the opening and closing of the partition (401).

10. The steel melting apparatus according to claim 9, characterized in that: At the bottom of the preheating zone (403), a rotary drive motor (410) connected to the baffle claw (404) is also provided. The baffle claw (404) is driven by the rotary drive motor (410) to swing and rise and fall in an arc, thereby realizing the opening and closing of the baffle claw (404).

11. The steel melting apparatus according to claim 10, characterized in that: The material stopper (404) also has a cooling medium channel (4041) and a cooling medium inlet (4042) and a cooling medium outlet (4043) connected to the cooling medium channel (4041).

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