Environment-friendly waste steel preheating system

Abstract

The utility model relates to the technical field of steelmaking. The utility model relates to a preheating system, in particular to an environment-friendly waste steel preheating system. Comprising a scrap steel feeding section, a scrap steel preheating section, a scrap steel pre-heating section and a waste heat power generation device, the discharging end of the scrap steel feeding section is connected with the feeding end of the scrap steel pre-heating section, and the discharging end of the scrap steel pre-heating section is connected with the feeding end of the scrap steel preheating section; and an air outlet of the scrap preheating section is communicated with an air inlet of the waste heat power generation device. Aiming at the problem that dioxin can be generated in the existing scrap steel preheating technology, the utility model provides the environment-friendly scrap steel preheating system, the greenization of the electric furnace is promoted, the waste heat utilization of the flue gas of the electric furnace and the green preheating of scrap steel are realized, and the greenization and high-efficiency smelting of the flue gas of the electric furnace are realized at the same time.

Description

Technical Field

[0001] This utility model relates to the field of steelmaking technology. More specifically, this utility model relates to an environmentally friendly scrap steel preheating system. Background Technology

[0002] The steel industry faces pressure to shift from "dual control of energy consumption" to "dual control of carbon emissions," making the transformation from the traditional "blast furnace-converter" long-process technology to the "electric arc furnace" short-process technology the future development direction of the steel industry. The short-process technology, using scrap steel as raw material and electricity as the carrier, has certain shortcomings in terms of overall cost, and this situation is unlikely to change fundamentally in the short term. Therefore, production enterprises mainly using the "electric arc furnace" short-process technology generally face the practical need for "optimization of furnace charge structure, improvement of operating methods, and reduction of production costs."

[0003] Currently, to address the insufficient competitiveness of short-process electric arc furnaces (EAFs), domestic and international EAF manufacturers are optimizing and researching continuous scrap feeding and efficient preheating technologies. Examples include Primetals' finger-type vertical shaft scrap preheating technology, Danieli and Tenon's horizontal continuous feeding preheating, MCC Saidi's stepped scrap feeding, and MCC Jingcheng's horizontal-vertical shaft composite scrap preheating technology. These technologies aim to reduce EAF energy consumption through efficient scrap preheating. However, in these preheating technologies, the EAF flue gas temperature drops to between 400 and 700°C after scrap preheating. Due to the strong thermal stability of dioxins, they require heating to around 750°C to begin decomposition. When the EAF flue gas temperature is below 800°C after preheating, large amounts of dioxins are often produced, which contradicts the concept of green development. Using natural gas or other methods to heat the flue gas would increase costs, negating its advantage in cost reduction and efficiency improvement for EAFs. Therefore, developing a scrap steel heating process that can both ensure the green and environmentally friendly operation of electric furnaces and achieve energy saving and consumption reduction through scrap steel preheating is of great value. Utility Model Content

[0004] This invention addresses the problem of dioxins generated by existing scrap steel preheating technologies by providing an environmentally friendly scrap steel preheating system. This system promotes the greening of electric arc furnaces and enables the utilization of waste heat from electric arc furnace flue gas and the green preheating of scrap steel, thus combining greening of electric arc furnace flue gas with high-efficiency smelting.

[0005] To achieve these objectives and other advantages according to this utility model, an environmentally friendly scrap steel preheating system is provided, comprising a scrap steel feeding section, a scrap steel preheating section, a scrap steel preheating section, and a waste heat power generation device. The discharge end of the scrap steel feeding section is connected to the feed end of the scrap steel preheating section, the discharge end of the scrap steel preheating section is connected to the feed end of the scrap steel preheating section, and the air outlet of the scrap steel preheating section is connected to the air inlet of the waste heat power generation device.

[0006] Furthermore, in the aforementioned environmentally friendly scrap steel preheating system, the waste heat power generation device is connected to the scrap steel preheating section to supply the electrical energy obtained from the waste heat power generation of the preheated electric furnace flue gas to the scrap steel preheating section.

[0007] Furthermore, the aforementioned environmentally friendly scrap steel preheating system also includes a dynamic sealing section, through which the discharge end of the scrap steel preheating section and the discharge end of the scrap steel preheating section are connected.

[0008] Furthermore, the aforementioned environmentally friendly scrap steel preheating system also includes a connecting trolley that moves between the discharge end of the scrap steel preheating section and the feed end of the electric furnace.

[0009] Furthermore, in the aforementioned environmentally friendly scrap steel preheating system, the scrap steel preheating section is an induction heating device.

[0010] Furthermore, in the aforementioned environmentally friendly scrap steel preheating system, the waste heat power generation device is a waste heat boiler.

[0011] Furthermore, in the aforementioned environmentally friendly scrap steel preheating system, the heating temperature of the scrap steel preheating section is below 300°C.

[0012] Furthermore, in the aforementioned environmentally friendly scrap steel preheating system, the outlet temperature of the scrap steel preheating section is not lower than 800°C.

[0013] The beneficial effects of this utility model are:

[0014] 1. This invention preheats the scrap steel using induction heating before it enters the preheating process via electric arc furnace flue gas. This reduces the pressure on the scrap steel from the subsequent preheating by the electric arc furnace flue gas, making it easier to control the temperature of the preheated electric arc furnace flue gas above 800℃. Simultaneously, the heating temperature during induction heating is below 300℃, which also reduces the possibility of dioxin formation. This invention fully considers the dioxin formation range and effectively avoids it.

[0015] 2. This utility model controls the temperature of the preheated electric furnace flue gas above 800℃ to avoid the production of dioxins in the electric furnace flue gas within the temperature range of 300-800℃; at the same time, it adopts waste heat power generation technology to utilize the preheated electric furnace flue gas, and uses the recovered electricity to feed back the preheating of scrap steel, thereby realizing the recovery and reuse of waste heat from the electric furnace flue gas.

[0016] 3. This utility model is mainly aimed at the preheating scheme of continuously fed scrap steel. It can be designed and modified on existing continuously fed scrap steel preheating equipment to maintain a high flue gas outlet temperature and meet the requirements of scrap steel preheating effect, ultimately achieving a win-win situation of green and efficient electric arc furnace smelting.

[0017] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the environmentally friendly scrap steel preheating system described in this invention.

[0019] The reference numerals in the attached figures are as follows:

[0020] 1. Electric furnace; 2. Connecting trolley; 3. Scrap steel preheating section; 4. Dynamic sealing section; 5. Waste heat power generation device; 6. Scrap steel preheating section; 7. Scrap steel feeding section. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments, so that those skilled in the art can implement it based on the description.

[0022] It should be noted that in the description of this utility model, the terms "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0023] like Figure 1 As shown, an embodiment of this utility model provides an environmentally friendly scrap steel preheating system, including a scrap steel feeding section, a scrap steel preheating section, a scrap steel preheating section, and a waste heat power generation device. The discharge end of the scrap steel feeding section is connected to the feed end of the scrap steel preheating section, and the discharge end of the scrap steel preheating section is connected to the feed end of the scrap steel preheating section. The air outlet of the scrap steel preheating section is connected to the air inlet of the waste heat power generation device. The heating temperature of the scrap steel preheating section is below 300°C; the outlet temperature of the scrap steel preheating section is not lower than 800°C.

[0024] In this embodiment, the scrap steel feeding section, scrap steel preheating section, scrap steel preheating section, and waste heat power generation device can all utilize existing technologies. Each of these sections is equipped with conveying equipment. Scrap steel can be hoisted into the trough of the scrap steel feeding section using a chain conveyor, disc crane, or steel grabber. The conveying equipment in the scrap steel feeding section evenly transports the scrap steel to the scrap steel preheating section, where it is preheated. During the heating process, the conveying equipment in the preheating section propels the scrap steel forward until it reaches the scrap steel preheating section, thus completing the preheating of the scrap steel. The high-temperature flue gas from the electric furnace enters the scrap steel preheating section and then flows into the waste heat power generation device through its outlet. The flue gas from the electric furnace heats the scrap steel in the preheating section as it flows through it.

[0025] During the operation of the scrap steel preheating system, the temperature of the electric furnace flue gas at the outlet of the scrap steel preheating section must be controlled above 800℃, meaning the temperature of the preheated electric furnace flue gas needs to be greater than 800℃. Currently, the length of the scrap steel preheating section in a typical scrap steel preheating system is 30m. This length can be reduced to no more than 15m to shorten the residence time of the electric furnace flue gas in the preheating section, thereby increasing the temperature of the electric furnace flue gas discharged from the preheating section. This ensures that the outlet temperature of the preheated electric furnace flue gas is not lower than 800℃, preventing the formation of dioxins.

[0026] Furthermore, existing technology indicates that the temperature range most conducive to dioxin formation is 300 to 750°C. Within this temperature range, various activities can lead to dioxin formation, including steel and non-ferrous metal smelting, vehicle exhaust emissions, and the incineration of various wastes, such as pharmaceutical wastewater, chemical waste, municipal solid waste, and waste from coal-fired power plants. Especially when combustion temperatures are below 300 to 400°C, leaded gasoline, coal, treated wood, and petroleum products are more likely to generate dioxins. In addition, the production processes of polyvinyl chloride (PVC) plastics, paper, chlorine, and certain pesticides may also release dioxins into the environment. The scrap steel in this application primarily originates from waste recycling and, in addition to metallic components, may contain various impurities. If the preheating temperature of the scrap steel exceeds 300°C, dioxins may be generated during the heating process. Therefore, controlling the preheating temperature of the scrap steel below 300°C can minimize dioxin formation during preheating.

[0027] The temperature of the electric arc furnace flue gas at the outlet of the scrap steel preheating section is controlled above 800℃ to prevent the production of dioxins in the flue gas within the temperature range of 300-800℃. Simultaneously, the heat energy of the electric arc furnace flue gas discharged from the scrap steel preheating section is recovered and utilized through a waste heat power generation device. A connecting trolley is installed at the discharge end of the scrap steel preheating section, connecting to the discharge end of the section and feeding the preheated scrap steel into the electric arc furnace via the connecting trolley.

[0028] Preferably, in another embodiment of the present invention, the waste heat power generation device is connected to the scrap steel preheating section so as to supply the electrical energy obtained from the preheated electric furnace flue gas waste heat power generation to the scrap steel preheating section.

[0029] In this embodiment, the electricity generated by the waste heat of the preheated electric furnace flue gas is used to preheat the scrap steel, thereby realizing the recycling of energy during the preheating process of the scrap steel.

[0030] Preferably, as another embodiment of the present invention, it further includes a dynamic sealing section, wherein the discharge end of the scrap steel preheating section and the discharge end of the scrap steel preheating section are connected through the dynamic sealing section.

[0031] In this embodiment, the scrap steel preheating section and the scrap steel preheating section are connected by a dynamic sealing section, which seals the connection between the two to prevent wind from entering the scrap steel preheating section.

[0032] Preferably, as another embodiment of the present invention, it further includes a connecting trolley that moves between the discharge end of the scrap steel preheating section and the feed end of the electric furnace.

[0033] In this embodiment, a connecting trolley is provided at the discharge end of the scrap steel preheating section. The discharge end of the scrap steel preheating section is connected to the connecting trolley, and the preheated scrap steel is sent into the electric furnace through the connecting trolley.

[0034] Preferably, in another embodiment of the present invention, the preheating section of the scrap steel is an induction heating device.

[0035] In this embodiment, induction heating is suitable for metallic materials, and it has the advantages of fast heating speed, high energy efficiency and precise temperature control, so as to better control the temperature of scrap steel after preheating.

[0036] Preferably, in another embodiment of the present invention, the waste heat power generation device is a waste heat boiler.

[0037] In this embodiment, the waste heat boiler is an important piece of equipment for waste heat power generation. It uses the heat or combustible material in the working fluid such as waste gas and waste liquid as a heat source to produce steam for power generation. In this embodiment, the waste heat boiler uses the flue gas from the electric furnace as a heat source to recover and utilize the waste heat of the flue gas.

[0038] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and embodiments shown and described herein.

Claims

1. An environmentally friendly scrap steel preheating system, characterized in that, It includes a scrap steel feeding section, a scrap steel preheating section, a scrap steel preheating section, and a waste heat power generation device. The discharge end of the scrap steel feeding section is connected to the feed end of the scrap steel preheating section, the discharge end of the scrap steel preheating section is connected to the feed end of the scrap steel preheating section, and the air outlet of the scrap steel preheating section is connected to the air inlet of the waste heat power generation device.

2. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, The waste heat power generation device is connected to the scrap steel preheating section so as to supply the electrical energy obtained from the preheated electric furnace flue gas waste heat power generation to the scrap steel preheating section.

3. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, It also includes a dynamic sealing section, through which the discharge end of the scrap steel preheating section and the discharge end of the scrap steel preheating section are connected.

4. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, It also includes a connecting trolley that moves between the discharge end of the scrap preheating section and the feed end of the electric furnace.

5. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, The preheating section for scrap steel is an induction heating device.

6. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, The waste heat power generation device is a waste heat boiler.

7. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, The heating temperature of the preheating section for the scrap steel is below 300°C.

8. The environmentally friendly scrap steel preheating system as described in claim 1, characterized in that, The outlet temperature of the scrap steel preheating section shall not be lower than 800℃.

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