An electric furnace flue gas treatment system

Abstract

The present invention relates to an electric furnace flue gas treatment system, including a primary flue gas treatment system in the furnace, the primary flue gas treatment system in the furnace including a primary dust removal device, a flue gas treatment device, a dioxin treatment device, a main fan and a chimney which are sequentially connected through a flue gas pipeline, the primary dust removal device adopts a high-temperature dust collector, and the primary dust removal device is used to receive the flue gas of the electric furnace. The present invention uses a high-temperature dust collector to remove dust first and then treat the flue gas, which can avoid a large amount of fine adhesive dust in the high-temperature gas and adhere to the flue gas treatment device, thereby reducing the maintenance workload and operation resistance, and at the same time improving the heat transfer efficiency and service life of the flue gas treatment device.

Description

Technical Field

[0001] The invention relates to the field of dust removal equipment, and in particular to an electric furnace fume treatment system. Background Art

[0002] The flue gas emitted by the electric furnace is mainly divided into two types: primary flue gas and secondary flue gas. Among them: primary flue gas generally refers to the exhaust gas in the electric furnace during electric furnace smelting and scrap steel preheating, that is, the high-temperature dusty flue gas discharged from the 4th or 2nd hole during electric furnace smelting. The commonly used furnace exhaust forms include direct type, horizontal disconnection type and elbow disconnection type. Secondary flue gas refers to the flue gas overflowing from the furnace during charging, tapping, smelting and preheating of the electric furnace. This type of flue gas is generally captured by closed hoods and roof hoods.

[0003] In the initial stage of my country's electric furnace dust removal technology, the technology was mainly introduced from some European countries such as Germany and Italy. On the basis of introducing advanced technology, it was transformed in combination with my country's own characteristics. The overall exhaust gas volume of the electric furnace is very large, and the electric furnace smelting process is complicated. Before dealing with this type of flue gas, it is necessary to first collect the flue gas generated during its operation. The main forms of domestic electric furnace flue gas capture are: closed hood, semi-closed hood, roof hood, 4-hole (or 2-hole) exhaust + roof hood, 4-hole (or 2-hole) exhaust + closed hood + roof hood, etc. The dust removal design of the electric furnace steelmaking workshop can be combined into a variety of dust removal schemes as needed due to the different process design and layout of the workshop.

[0004] (I) The dust removal of primary flue gas inside the electric furnace and secondary flue gas outside the electric furnace are set separately:

[0005] (1) Primary flue gas treatment system in electric furnace:

[0006] After being discharged from the electric furnace, the flue gas is cooled by a water-cooled elbow, passes through a combustion settling chamber, and is burned to remove harmful gases such as CO and organic waste gas in the flue gas. It is then cooled by a water-cooled flue and a forced air cooler (or an air natural cooler), enters a bag filter for dust removal, and is discharged after meeting the standards.

[0007] (2) Secondary flue gas treatment system outside the electric furnace:

[0008] The secondary flue gas outside the electric furnace is collected by the electric furnace closed hood and the electric furnace roof hood and then enters the bag dust collector and is discharged after meeting the standards.

[0009] (II) Mixed dust removal setting for primary flue gas inside the electric furnace and secondary flue gas outside the electric furnace:

[0010] The primary flue gas in the electric furnace is mixed with the secondary flue gas outside the electric furnace collected by the electric furnace roof cover or (and) the electric furnace closed cover after water cooling, spark capture, strong cooling or air cooling, and enters the bag dust collector together and is discharged after meeting the standards.

[0011] (III) The dust removal setting of the primary dust removal inside the electric furnace and the secondary dust removal outside the electric furnace is both independent and coordinated

[0012] The primary dust removal during electric furnace smelting also shares part of the secondary smoke exhaust volume, so that the fan of the secondary dust removal system can be greatly reduced in speed during electric furnace smelting to save energy, and only increase in speed during charging and steel tapping. At the same time, the high-temperature dust collector of the primary dust removal of the electric furnace can be replaced by a normal temperature dust collector, reducing equipment investment and operating costs.

[0013] The conventional traditional electric furnace dust removal system is designed with large air volume, high investment and high energy consumption. It usually adopts the method of cooling first and then dust removal, which cannot effectively utilize the heat of the flue gas; or it adopts the method of first mixing cold air into the dusty flue gas to partially cool it down and then recovering part of the heat through the waste heat boiler. This method wastes a lot of energy and makes the system bulky due to the mixing of a large amount of air. More importantly, the electric furnace flue gas has not been dusted, and the high-temperature gas contains a large amount of fine adhesive dust and will adhere to the heating surface of the heat pipe, thereby increasing the maintenance workload and operating resistance, while reducing the heat transfer efficiency and service life of the heating surface of the heat pipe; in addition, there is no effective means to remove dioxins in the electric furnace flue gas.

[0014] Patent CN 210346366 U specifically discloses a steel plant electric furnace flue gas treatment system, including a primary flue gas dust removal system inside the furnace and a secondary flue gas dust removal system outside the furnace. The primary flue gas dust removal system inside the furnace includes a flue gas cooling flue, a combustion settling chamber, a waste heat recovery device, a primary side dust removal device, an adsorbent injection device, and a primary side dust collection device; the secondary flue gas dust removal system outside the furnace includes an external flue gas capture component, a secondary side dust removal device, and a secondary side dust collection device. A flue gas connecting pipe is connected between the primary flue gas dust removal system inside the furnace and the secondary flue gas dust removal system, and a regulating valve is provided on the flue gas connecting pipe. This patent allows the flue gas from the electric furnace to be cooled through the flue gas cooling duct and then enter the waste heat boiler directly without dust removal. The high-temperature gas contains a large amount of fine adhesive dust and will adhere to the heating surface of the heat pipe, thereby increasing the maintenance workload and operating resistance, while reducing the heat transfer efficiency and service life of the heating surface of the heat pipe; and by spraying activated carbon on the pipe in front of the primary dust collector to adsorb and remove dioxin pollutants, this method has low adsorption efficiency, and the activated carbon (hazardous waste) that adsorbs dioxins is mixed with the electric furnace ash. The contaminated electric furnace ash is at risk of being classified as hazardous waste. The flue gas temperature at the outlet of the waste heat boiler is relatively high, and cold air needs to be added to reduce the flue gas temperature to ensure the adsorption efficiency of the activated carbon. The equipment, control and interlocking protection of the dust removal system will become more complicated. Summary of the invention

[0015] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an electric furnace flue gas treatment system. Through a high-temperature dust collector, dust is removed first and then the flue gas is treated. This can prevent the high-temperature gas from containing a large amount of fine adhesive dust and adhering to the flue gas treatment device, thereby reducing the maintenance workload and operating resistance, and at the same time improving the heat transfer efficiency and service life of the flue gas treatment device.

[0016] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0017] An electric furnace flue gas treatment system includes a primary flue gas treatment system in the furnace, the primary flue gas treatment system in the furnace includes an electric furnace, a primary dust removal device, a flue gas treatment device, a dioxin treatment device, a main fan and a chimney connected in sequence through a flue gas pipeline, the primary dust removal device adopts a high-temperature dust collector, and the primary dust removal device is used to receive the flue gas of the electric furnace. In a specific embodiment, a high-temperature dust collector is adopted. On the basis of a traditional bag dust collector, a filter bag made of ceramic and metal materials is adopted to break through the use temperature limit of traditional chemical fiber filter bags (less than or equal to 260°C), meet the dust removal requirements of 260-850°C high-temperature flue gas, can directly filter high-temperature flue gas, and a low-dust environment can protect waste heat recovery equipment and improve recovery efficiency. At the same time, dust removal before flue gas treatment can avoid a large amount of fine adhesive dust in the high-temperature gas and adhere to the flue gas treatment device, thereby reducing maintenance workload and operating resistance, and at the same time improving the heat transfer efficiency and service life of the flue gas treatment device.

[0018] Metal filter bags are mainly made of sintered metal fibers or metal powders. Sintered metal fiber filter bags are made of metal fibers with a diameter of micron level through non-woven paving, stacking, and high-temperature sintering. Sintered metal powder filter bags are made by molding pre-melted powder into tubes or porous plates and then sintering at high temperature. Its main materials include 316L, 310S, 00Cr20Al5, Hastelloy, etc., and the long-term use temperature can reach 200℃-900℃.

[0019] Ceramic filter cartridges are made of high porosity, low-density ceramic fibers (about 2-3 microns in diameter) wound around them. The basic materials are aluminum silicate fibers and inorganic adhesives. Ceramic fiber raw materials are not easy to react with chemical substances, and can be used for a long time at a maximum temperature of less than 800°C, and can withstand a temperature change of 1000°C for a short time. At the same time, they have good rigidity and do not require a bag cage or other similar frame structure.

[0020] Optionally, the system also includes an off-furnace secondary flue gas treatment system, which includes an off-furnace secondary flue gas capture device, a secondary dust removal device, a main fan and a chimney that are sequentially connected through a flue gas duct. The off-furnace secondary flue gas capture device can be a molten iron chute exhaust hood for capturing flue gas generated when the electric furnace chute is mixed with molten iron, an electric furnace enclosed hood for capturing flue gas overflowing from the electrode hole during the electric furnace mixing with iron and scrap steel, steel tapping and smelting, and an electric furnace roof hood. In a specific embodiment, an electric furnace enclosed hood and an electric furnace roof hood are used. In a specific embodiment, the secondary dust removal device uses multiple groups of normal temperature bag dust collectors, and the multiple groups of normal temperature bag dust collectors are arranged in parallel.

[0021] Optionally, the secondary flue gas treatment system outside the furnace is connected to the primary flue gas treatment system inside the furnace through a connecting flue gas pipe, and a regulating valve is provided on the connecting flue gas pipe to control whether the secondary flue gas treatment system outside the furnace is connected to the primary flue gas treatment system inside the furnace. The setting of the regulating valve allows the secondary flue gas treatment system outside the furnace to be connected to the primary flue gas treatment system inside the furnace through the flue gas pipe, and introduces the secondary normal temperature flue gas into the primary flue gas to adjust the flue gas temperature. After the two flue gases are mixed and cooled, they safely enter the dioxin treatment device to ensure the safe and stable operation of the system without affecting the normal production of the electric furnace. Compared with the direct use of a cold air valve (directly mixing cold air), this method can adjust the flue gas temperature without introducing additional flue gas.

[0022] Optionally, the flue gas treatment device includes a high-temperature flue gas treatment section and a low-temperature flue gas treatment section, and the flue gas treated by the high-temperature flue gas treatment section is introduced into the low-temperature flue gas treatment section for treatment, and the temperature of the flue gas treated by the high-temperature flue gas treatment section is lower than 250° C., and the temperature of the flue gas treated by the low-temperature flue gas treatment section is lower than 170° C. Two-stage waste heat recovery is adopted to give full play to the waste heat effect, while ensuring that the flue gas temperature is below the safe and efficient operating temperature of activated carbon adsorption.

[0023] Optionally, the high-temperature flue gas treatment section uses a waste heat boiler to recover the waste heat of the high-temperature section of the primary flue gas of the electric furnace after high-temperature dust removal. In a specific embodiment, a cooling wall membrane type waste heat boiler, a heat pipe type waste heat boiler or a fuel-mixed combined waste heat boiler can be used. The low-temperature flue gas treatment section uses an air-water heat exchanger to further recover the waste heat of the low-temperature section of the flue gas discharged from the waste heat boiler. The air-water heat exchanger is a conventional device in the prior art.

[0024] Optionally, the dioxin treatment device is used to remove toxic and harmful pollutants such as dioxins from flue gas. It can use an activated carbon adsorption device based on the adsorption removal principle, including two methods: a moving bed and a fixed bed; or a dioxin removal device based on the catalytic oxidation decomposition principle. Compared with the activated carbon adsorption device, the dioxin removal device based on the catalytic oxidation decomposition principle has a different principle, a better and more stable decomposition effect, and is not affected by the environment.

[0025] In particular, the dioxin removal device here is based on a functional new material of nano-adsorbent material coupled with a catalytic decomposition agent, which achieves in-situ catalytic decomposition treatment of low-concentration dioxin adsorption and accumulation, and decomposes dioxin into water, oxygen and hydrogen chloride without secondary pollution and harmful byproducts. In particular, compared with activated carbon, this functional new material can be simply regenerated online, recovering more than 90% of the decomposition capacity, and can be recycled 5-10 times under normal working conditions.

[0026] Nano-adsorption materials mainly include carbon nanotubes, etc. By making targeted improvements and enhancements to the surface of carbon nanotube channels, the aggregation rate of dioxins is increased, ensuring that low-concentration dioxins can be quickly catalytically decomposed. Carbon nanotubes have a small diameter and a large surface energy. Under the influence of van der Waals forces and the interaction of π electrons, they easily attract each other to form larger aggregates, affecting their dispersion in polymers. In order to improve the interfacial adhesion between carbon nanotubes and polymers, physical and chemical modifications are usually performed on the surface of carbon nanotubes. Physical modification mainly modifies the surface of carbon nanotubes through adsorption, coating and coating. This method does not damage the structure of carbon nanotubes and retains the original excellent properties of carbon nanotubes. Chemical modification is a chemical reaction between carbon nanotubes and modifiers to change the surface structure and state of carbon nanotubes. Both physical and chemical modifications can improve the dispersibility of carbon nanotubes.

[0027] The catalytic decomposition agent contains transition metal oxides, copper and other metals and their oxides, among which transition metal oxides such as V2O5 and TiO2 mainly play the role of in-situ and real-time decomposition of dioxins accumulated in the pores. Copper, iron, manganese and other metals and their oxides mainly play a catalytic dechlorination role to prevent chlorine atoms from affecting the catalytic decomposition reaction, and can provide a dioxin removal efficiency of more than 95% at a relatively low temperature.

[0028] Optionally, a first shut-off valve is provided on the flue gas pipeline at the flue gas inlet and outlet of the high-temperature flue gas treatment section, respectively, and a first flue gas pipeline is also provided between the flue gas outlet of the primary dust removal device and the flue gas inlet of the low-temperature flue gas treatment section. A second shut-off valve for controlling whether the primary dust removal device is connected to the low-temperature flue gas treatment section is provided on the first flue gas pipeline. When the first shut-off valve is closed, the high-temperature flue gas treatment section is offline, the second shut-off valve controls the primary dust removal device to be connected to the low-temperature flue gas treatment section through the first flue gas pipeline, and the regulating valve controls the secondary flue gas treatment system outside the furnace to be connected to the first flue gas pipeline through the flue gas pipeline. In a specific embodiment, when the high-temperature flue gas treatment section fails, it is taken offline through the first shut-off valve, and at the same time, the secondary normal-temperature flue gas is introduced into the primary flue gas through the flue connecting the primary flue gas treatment system and the secondary flue gas treatment system. After the two flue gases are mixed and cooled, they pass through the gas-water heat exchanger and safely enter the dioxin treatment device, ensuring that the system operates safely and stably without affecting the normal production of the electric furnace.

[0029] Optionally, a third shut-off valve is provided on the flue gas pipeline at the flue gas inlet and outlet of the low-temperature flue gas treatment section, respectively, and a second flue gas pipeline is provided between the flue gas outlet of the high-temperature flue gas treatment section and the flue gas inlet of the dioxin treatment device. A fourth shut-off valve for controlling whether the high-temperature flue gas treatment section is connected to the dioxin treatment device is provided on the second flue gas pipeline. When the third shut-off valve is closed, the low-temperature flue gas treatment section is offline, the fourth shut-off valve controls the high-temperature flue gas treatment section to be connected to the dioxin treatment device through the second flue gas pipeline, and the regulating valve furnace secondary flue gas treatment system is connected to the second flue gas pipeline through the flue gas pipeline. In a specific embodiment, when the low-temperature flue gas treatment section fails, it is taken offline through the third shut-off valve, and at the same time, the secondary normal temperature flue gas is introduced into the primary flue gas through the flue connecting the primary flue gas treatment system and the secondary flue gas treatment system. After the two flue gases are mixed and cooled, they enter the dioxin treatment device safely, ensuring the safe and stable operation of the system without affecting the normal production of the electric furnace.

[0030] Optionally, after closing the first shut-off valve and the third shut-off valve at the same time, the second shut-off valve and the fourth shut-off valve control the primary dust removal device to be connected to the dioxin treatment device through the first flue gas duct and the second flue gas duct, and the regulating valve controls the secondary flue gas treatment system outside the furnace to be connected to the first flue gas duct through the flue gas duct. In a specific embodiment, when the high and low temperature flue gas treatment sections fail at the same time, they are taken offline through the first and third shut-off valves, and at the same time, the primary and secondary flue gases are mixed and cooled through the flue connecting the primary flue gas treatment system and the secondary flue gas treatment system, and then safely enter the dioxin treatment device, ensuring the safe and stable operation of the system without affecting the normal production of the electric furnace.

[0031] Optionally, a combustion settling chamber and a cooling flue are provided in sequence between the electric furnace and the primary dust removal device. In a specific embodiment, the combustion settling chamber is used to fully burn the CO gas contained in the flue gas to ensure safety; and to settle the large particles contained in the flue gas to reduce the load of subsequent dust removal. The cooling flue is used to reduce the primary high-temperature flue gas in the electric furnace from about 1400°C to the inlet temperature of 350-700°C for the economic operation of the waste heat boiler, ensuring economical and efficient waste heat recovery. The cooling flue can be a traditional water-cooled flue, or a more energy-saving vaporization cooling flue can be used instead of a traditional water-cooled flue. While ensuring the cooling of the flue gas, the initial high-temperature flue gas is vaporized for waste heat recovery to produce steam for production and life use.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. The present invention uses a high-temperature dust collector to remove dust first and then recover waste heat, which can prevent the high-temperature gas from containing a large amount of fine adhesive dust and adhering to the heating surface of the heat pipe of the waste heat boiler, thereby reducing the maintenance workload and operating resistance, and at the same time improving the heat transfer efficiency and service life of the heating surface of the heat pipe;

[0034] 2. The present invention effectively improves the efficiency of adsorption and removal of pollutants such as dioxins by independently setting up a dioxin treatment device in the low-temperature section, and avoids the risk of electric furnace dust being classified as hazardous waste;

[0035] 3. The pollutant collaborative treatment of the system of the present invention is efficient and safe, the system protection measures are perfect, and the primary flue gas treatment system and the secondary flue gas treatment system of the electric furnace can take care of each other and operate in an energy-saving manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of an embodiment of the present invention;

[0037] Among them, 1. Primary flue gas treatment system in the furnace; 11. Combustion and sedimentation chamber; 12. Vaporization cooling flue; 13. High-temperature dust collector; 14. Waste heat boiler; 15. Air-water heat exchanger; 16. Activated carbon adsorption bed; 17. Main fan; 18. Chimney; 2. Secondary flue gas treatment system outside the furnace; 21. Electric furnace closed cover; 22. Electric furnace roof cover; 23. Secondary dust removal device; 24. Main fan; 25. Chimney; 3. Regulating valve; 4. First shut-off valve; 5. First flue gas duct; 6. Second shut-off valve; 7. Third shut-off valve; 8. Second flue gas duct; 9. Fourth shut-off valve. DETAILED DESCRIPTION

[0038] In order to make the technical solutions and beneficial effects of the present invention more clearly understandable, the following is a detailed description by listing specific embodiments. The drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application belongs.

[0039] In the present invention, unless otherwise clearly defined, the terms "installed", "connected", "connected", "connected" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] As attached Figure 1 An electric furnace flue gas treatment system shown includes a primary flue gas treatment system 1 inside the furnace and a secondary flue gas treatment system 2 outside the furnace.

[0041] The primary flue gas treatment system 1 in the furnace includes a combustion settling chamber 11 connected to the interior of the electric furnace, a vaporization cooling flue 12 connected to the combustion settling chamber 11, a high-temperature dust collector 13 connected to the cooling flue 12, a waste heat boiler 14 connected to the high-temperature dust collector 13, an air-water heat exchanger 15 connected to the waste heat boiler 14, an activated carbon adsorption bed 16 connected to the air-water heat exchanger 15, a main fan 17 connected to the activated carbon adsorption bed 16, and the main fan 17 is connected to the chimney 18.

[0042] In this embodiment, the activated carbon adsorption bed 16 has the advantages of more uniform contact with the pollutants, longer contact duration, and no interference from other dust and smoke. At the same time, compared with the method of spraying activated carbon in front of the dust collector, the lower the temperature at the end of the activated carbon adsorption bed 16, the higher the efficiency and the higher the safety.

[0043] In other specific embodiments, the activated carbon adsorption bed 16 can be replaced by a dioxin removal device based on the catalytic oxidation decomposition principle. Compared with the activated carbon adsorption device, the two have different principles. The dioxin removal device based on the catalytic oxidation decomposition principle has a better and more stable decomposition effect and is not affected by the environment.

[0044] The primary high-temperature flue gas in the electric furnace passes through the combustion settling chamber 11 and the vaporization cooling flue 12 to reduce its temperature to 350-700°C, and then enters the high-temperature dust collector 13 for dust removal. The waste heat boiler 14 recovers the waste heat of the high-temperature flue gas after dust removal and purification. After the flue gas temperature drops to about 220°C, it enters the air-water heat exchanger 15 to recover the waste heat of the low-temperature flue gas. The temperature is further reduced to below 150°C, and the temperature is reduced to the safe and efficient temperature of activated carbon adsorption. It enters the activated carbon adsorption bed 16 to remove toxic and harmful pollutants such as dioxins, and finally meets the emission standards.

[0045] The secondary flue gas treatment system 2 outside the furnace includes an electric furnace closed cover 21, an electric furnace roof cover 22 connected to the electric furnace closed cover 21, a secondary dust removal device 23 connected to the electric furnace roof cover 22, a main fan 24 connected to the bag dust collector 23, and the main fan 24 is connected to the chimney 25. The secondary dust removal device 23 includes multiple groups of bag dust collectors, and the multiple groups of bag dust collectors are arranged in parallel. The figure takes two groups as an example, and the two groups of bag dust collectors share one main fan 24. The secondary flue gas outside the electric furnace is collected by the electric furnace closed cover 21 and the electric furnace roof cover 22 and then enters the normal temperature bag dust collector, and is discharged after meeting the standards.

[0046] The secondary flue gas treatment system 2 outside the furnace is connected to the primary flue gas treatment system 1 inside the furnace through a connecting flue gas pipeline, and a regulating valve 3 is provided on the connecting flue gas pipeline to control whether the secondary flue gas treatment system 2 outside the furnace is connected to the primary flue gas treatment system 1 inside the furnace. The regulating valve 3 is normally closed. When the waste heat boiler 14 or the air-water heat exchanger 15 fails, it needs to be opened to a certain degree according to the temperature control requirements.

[0047] A first shut-off valve 4 is respectively provided on the flue gas ducts at the flue gas inlet and outlet of the waste heat boiler 14. A first flue gas duct 5 is also provided between the flue gas outlet of the high-temperature dust collector 13 and the flue gas inlet of the air-water heat exchanger 15. The first flue gas duct 5 is provided with a second shut-off valve 6 for controlling whether the high-temperature dust collector 13 is connected to the air-water heat exchanger 15. When the waste heat boiler 14 fails, the first shut-off valve 4 is closed, that is, the waste heat boiler 14 is offline, and the second shut-off valve 6 is opened to control the high-temperature dust collector 13 to be connected to the air-water heat exchanger 15 through the first flue gas duct 5. The regulating valve 3 controls the secondary flue gas treatment system 2 outside the furnace to be connected to the first flue gas duct 5 through the flue gas duct, and the secondary normal temperature flue gas is introduced into the primary flue gas. After the two flue gases are mixed and cooled, they pass through the air-water heat exchanger 15 and safely enter the activated carbon adsorption bed 16, ensuring the safe and stable operation of the system without affecting the normal production of the electric furnace.

[0048] A third shut-off valve 7 is respectively provided on the flue gas pipes at the flue gas inlet and outlet of the gas-water heat exchanger 15. A second flue gas pipe 8 is also provided between the flue gas outlet of the waste heat boiler 14 and the flue gas inlet of the activated carbon adsorption bed 16. The second flue gas pipe 8 is provided with a fourth shut-off valve 9 for controlling whether the waste heat boiler 14 and the activated carbon adsorption bed 16 are connected. When the gas-water heat exchanger 15 fails, the third shut-off valve 7 is closed, the gas-water heat exchanger 15 is taken offline, and the fourth shut-off valve 9 is opened to control the waste heat boiler 14 and the activated carbon adsorption bed 16 to be connected through the second flue gas pipe 8. The regulating valve 3 controls the secondary flue gas treatment system 2 outside the furnace to be connected with the second flue gas pipe 8, so that the secondary normal temperature flue gas is introduced into the primary flue gas. After the two flue gases are mixed and cooled, they safely enter the activated carbon adsorption bed 16, ensuring the safe and stable operation of the system without affecting the normal production of the electric furnace.

[0049] When the waste heat boiler 14 and the gas-water heat exchanger 15 fail at the same time, the first shut-off valve 4 and the third shut-off valve 7 are closed, that is, the waste heat boiler 14 and the gas-water heat exchanger 15 are offline at the same time, the second shut-off valve 6 and the fourth shut-off valve 9 are opened, and the high-temperature dust collector 13 is controlled to be connected with the activated carbon adsorption bed 16 through the first flue gas pipeline 5 and the second flue gas pipeline 8, and the regulating valve 3 controls the secondary flue gas treatment system 2 outside the furnace to be connected with the first flue gas pipeline 5 through the flue gas pipeline. The secondary normal temperature flue gas is introduced into the primary flue gas, and after the two flue gases are mixed and cooled, they enter the activated carbon adsorption bed 16 safely to ensure the safe and stable operation of the system without affecting the normal production of the electric furnace.

[0050] The electric furnace fume treatment method of the present invention comprises the following steps:

[0051] (1) The primary high-temperature flue gas in the electric furnace during smelting is passed through the combustion settling chamber 11 and the vaporization cooling flue 12 to reduce the flue gas temperature to 350-700°C, and then enters the high-temperature dust collector 13 for dust removal;

[0052] (2) The purified high-temperature flue gas is passed through the waste heat boiler 14 to recover the waste heat of the high-temperature flue gas. After the flue gas temperature drops to about 220°C, it enters the air-water heat exchanger 15 to recover the waste heat of the low-temperature flue gas, and the temperature is further reduced to below 150°C;

[0053] (3) The cooled flue gas enters the activated carbon adsorption bed 16 to remove toxic and harmful pollutants such as dioxins, and finally reaches emission standards;

[0054] (4) The secondary flue gas during charging and tapping of the electric furnace is collected by the electric furnace closed cover 21 and the electric furnace roof cover 22 and then enters the secondary dust removal device 23 for dust removal and is discharged after meeting the standards.

[0055] Step (1) and step (4) are performed simultaneously, in no particular order.

[0056] When the waste heat boiler 14 fails, the first shut-off valve 4 is closed, that is, the waste heat boiler 14 is taken offline, and the second shut-off valve 6 is opened to control the high-temperature dust collector 13 to be connected with the air-water heat exchanger 15 through the first flue gas duct 5. The regulating valve 3 controls the secondary flue gas treatment system 2 outside the furnace to be connected with the first flue gas duct 5 through the flue gas duct, and the secondary normal temperature flue gas is introduced into the primary flue gas. After the two flue gases are mixed and cooled, they pass through the air-water heat exchanger 15 and safely enter the activated carbon adsorption bed 16 to continue to be treated.

[0057] When the gas-water heat exchanger 15 fails, the third shut-off valve 7 is closed, that is, the gas-water heat exchanger 15 is offline, and the fourth shut-off valve 9 is opened to control the waste heat boiler 14 to be connected with the activated carbon adsorption bed 16 through the second flue gas duct 8. The regulating valve 3 controls the secondary flue gas treatment system 2 outside the furnace to be connected with the second flue gas duct 8, and introduces the secondary flue gas at normal temperature into the primary flue gas. After the two flue gases are mixed and cooled, they safely enter the activated carbon adsorption bed 16 for further treatment.

[0058] When the waste heat boiler 14 and the gas-water heat exchanger 15 fail at the same time, close the first shut-off valve 4 and the third shut-off valve 7, that is, the waste heat boiler 14 and the gas-water heat exchanger 15 are offline at the same time, open the second shut-off valve 6 and the fourth shut-off valve 9, control the high-temperature dust collector 13 to be connected with the activated carbon adsorption bed 16 through the first flue gas duct 5 and the second flue gas duct 8, and control the regulating valve 3 to connect the secondary flue gas treatment system 2 outside the furnace with the first flue gas duct 5 through the flue gas duct, introduce the secondary normal temperature flue gas into the primary flue gas, and after the two flue gases are mixed and cooled, they safely enter the activated carbon adsorption bed 16 for further treatment.

[0059] Compared with the traditional electric furnace flue gas purification process, the present invention synergistically treats the pollutants of the electric furnace and recovers the waste heat by introducing a series of purification technologies such as high-temperature dust removal, multi-stage recovery of high-temperature waste heat and dioxin treatment equipment.

[0060] When the waste heat boiler, gas-water heat exchanger, etc. fail, they can be taken offline through the shut-off valve. Through the flue connecting the primary flue gas treatment system and the secondary flue gas treatment system, the primary and secondary flue gases are mixed and cooled and then safely enter the subsequent equipment, ensuring the safe and stable operation of the system without affecting the normal production of the electric furnace, so that the purification systems of the primary and secondary flue gases of the electric furnace can operate independently and coordinate management and safety protection.

[0061] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations included in the claims. Various modifications and changes may be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only express several implementations of the present invention and do not limit the scope of protection of the patent of the present invention.

Claims

1. An electric furnace flue gas treatment system, characterized in that: It includes a primary flue gas treatment system in the furnace, which includes a primary dust removal device, a flue gas treatment device, a dioxin treatment device, a main fan and a chimney which are sequentially connected through a flue gas pipeline. The primary dust removal device adopts a high-temperature dust collector and is used to receive the flue gas of the electric furnace; The flue gas treatment device comprises a high-temperature flue gas treatment section and a low-temperature flue gas treatment section. The flue gas treated by the high-temperature flue gas treatment section is introduced into the low-temperature flue gas treatment section for treatment. The temperature of the flue gas treated by the high-temperature flue gas treatment section is lower than 250°C, and the temperature of the flue gas treated by the low-temperature flue gas treatment section is lower than 150°C. The dioxin treatment device adopts an activated carbon adsorption device; The flue gas ducts at the flue gas inlet and outlet of the high-temperature flue gas treatment section are respectively provided with first shut-off valves, and a first flue gas duct is also provided between the flue gas outlet of the primary dust removal device and the flue gas inlet of the low-temperature flue gas treatment section. The first flue gas duct is provided with a second shut-off valve for controlling whether the primary dust removal device is connected to the low-temperature flue gas treatment section. When the first shut-off valve is closed, the high-temperature flue gas treatment section is offline, and the second shut-off valve controls the primary dust removal device to be connected to the low-temperature flue gas treatment section through the first flue gas duct. The regulating valve controls the secondary flue gas treatment system outside the furnace to be connected to the first flue gas duct through the flue gas duct. A third shut-off valve is respectively provided on the flue gas pipeline at the flue gas inlet and outlet of the low-temperature flue gas treatment section, a second flue gas pipeline is also provided between the flue gas outlet of the high-temperature flue gas treatment section and the flue gas inlet of the dioxin treatment device, and a fourth shut-off valve for controlling whether the high-temperature flue gas treatment section is connected to the dioxin treatment device is provided on the second flue gas pipeline. When the third shut-off valve is closed, the low-temperature flue gas treatment section is offline, the fourth shut-off valve controls the high-temperature flue gas treatment section to be connected to the dioxin treatment device through the second flue gas pipeline, and the regulating valve controls the secondary flue gas treatment system outside the furnace to be connected to the second flue gas pipeline through the flue gas pipeline; A third shut-off valve is respectively provided on the flue gas pipeline at the flue gas inlet and outlet of the low-temperature flue gas treatment section, a second flue gas pipeline is also provided between the flue gas outlet of the high-temperature flue gas treatment section and the flue gas inlet of the dioxin treatment device, and a fourth shut-off valve for controlling whether the high-temperature flue gas treatment section is connected to the dioxin treatment device is provided on the second flue gas pipeline. When the third shut-off valve is closed, the low-temperature flue gas treatment section is offline, the fourth shut-off valve controls the high-temperature flue gas treatment section to be connected to the dioxin treatment device through the second flue gas pipeline, and the regulating valve controls the secondary flue gas treatment system outside the furnace to be connected to the second flue gas pipeline through the flue gas pipeline. After the first shut-off valve and the third shut-off valve are closed at the same time, the second shut-off valve and the fourth shut-off valve control the primary dust removal device to be connected to the dioxin treatment device through the first flue gas pipeline and the second flue gas pipeline, and the regulating valve controls the secondary flue gas treatment system outside the furnace to be connected to the first flue gas pipeline through the flue gas pipeline; The high-temperature flue gas treatment section uses a waste heat boiler to recover the waste heat of the flue gas, and the low-temperature flue gas treatment section uses an air-water heat exchanger to recover the waste heat of the flue gas.

2. The electric furnace flue gas treatment system according to claim 1, characterized in that: It also includes an external secondary flue gas treatment system, which includes an external secondary flue gas capture device, a secondary dust removal device, a main fan and a chimney that are sequentially connected through a flue gas pipeline.

3. The electric furnace flue gas treatment system according to claim 2, characterized in that: The secondary flue gas treatment system outside the furnace is connected to the primary flue gas treatment system inside the furnace through a connecting flue gas pipeline, and a regulating valve is provided on the connecting flue gas pipeline to control whether the secondary flue gas treatment system outside the furnace is connected to the primary flue gas treatment system inside the furnace.

4. The electric furnace flue gas treatment system according to claim 1, characterized in that: A combustion settling chamber and a cooling flue are arranged in sequence between the electric furnace and the primary dust removal device.

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