Electric furnace flue gas waste heat power generation system based on parallel flue single steam superheat compensation supplementary combustion

Abstract

The application discloses a kind of based on parallel flue single steam superheating compensation afterburning electric furnace flue gas waste heat power generation system, comprising: parallel flue, it is set after settling chamber and is communicated with settling chamber, and parallel flue includes two flues of parallel design, one of which is arranged with steam superheater and constitutes steam superheating afterburning furnace flue, another flue is provided with tower-shaped flue without arranging heating surface and constitutes empty tower flue, wherein, afterburning process is carried out in steam superheater afterburning furnace flue.The application can greatly reduce afterburning gas consumption, and the afterburning gas consumption reduction rate reaches 20%-40%.The application can reduce flue gas emission, and realize that flue gas total amount is reduced by about 10%.The application can realize CO2 emission reduction, and the CO2 emission reduction rate is reduced by 10%-15%.

Description

Technical Field

[0001] This invention belongs to the field of high-efficiency power generation technology of electric furnace waste heat, specifically relating to an electric furnace flue gas waste heat power generation system based on parallel flue gas single steam superheat compensation and combustion. Background Technology

[0002] Short-process steelmaking is a major industrial adjustment direction for my country's steel industry to achieve carbon neutrality. Currently, the mainstream technology route for short-process steelmaking in my country is electric arc furnace (EAF) smelting + scrap preheating + EAF flue gas waste heat power generation. However, due to the discontinuity and instability of the EAF production process, the flue gas generated by EAF smelting (hereinafter referred to as EAF flue gas) has the following characteristics:

[0003] 1) The generation of electric arc furnace flue gas is intermittent, and its parameters exhibit complex fluctuations. During the smelting process in an electric arc furnace, the flue gas flow rate, temperature, composition, and dust content constantly change with variations in the steelmaking and tapping rhythms and smelting intensity, exhibiting complex periodic fluctuations. The flue gas temperature is highest, the flow rate is largest, and the dust content is highest during the oxidation period; conversely, the flue gas temperature is lowest, the flow rate is smallest, and the dust content is least during the tapping period.

[0004] 2) The flue gas contains high concentrations of dust with small particle sizes. The dust content is generally 8-15 g / m³, with a maximum of 30 g / m³. The particle size is generally distributed in the range of 0-30 μm, resulting in strong adsorption. In addition, the dust has a high Zn content, which makes the dust somewhat sticky, making it difficult to clean the heated surfaces.

[0005] 3) Large fluctuations in flue gas temperature. During the approximately 40-minute period of electric arc smelting, the flue gas temperature at the converter outlet fluctuates between 400℃ and 1400℃, with instantaneous temperatures reaching up to approximately 1800℃. For electric arc furnaces with scrap preheating, the outlet temperature of the scrap preheating system fluctuates between 250℃ and 850℃.

[0006] Electric arc furnace (EAF) flue gas waste heat power generation is an important technical means to recover waste heat from EAF flue gas, reduce power consumption per ton of steel, and decrease CO2 emissions per ton of steel. However, due to the complexity of EAF flue gas parameters, there are still some problems with EAF flue gas waste heat power generation technology. Existing scrap steel waste heat power generation systems generally include two main categories of technologies: EAF flue gas waste heat saturated steam power generation technology and EAF flue gas waste heat conventional combustion and supplementary superheated steam power generation technology. Currently, both of these systems have certain problems.

[0007] The saturated steam power generation technology using waste heat from electric arc furnace flue gas has the following problems: First, the enthalpy of the saturated steam is low, resulting in very low power generation efficiency; second, the high humidity of the exhaust steam exacerbates turbine cavitation problems. The conventional combustion and afterburning superheated steam power generation technology using waste heat from electric arc furnace flue gas has the following problems: First, the exhaust temperature of the superheated combustion furnace is high, generally above 350℃, leading to low thermal efficiency and high CO2 emissions per ton of steel. Second, the combustion furnace uses conventional combustion technology, resulting in high NO2 emissions. x The emissions are relatively large. Summary of the Invention

[0008] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0009] In view of the problems existing in the conventional combustion and superheated steam power generation technology of electric furnace flue gas waste heat, the purpose of this invention is to provide an electric furnace flue gas waste heat power generation system based on parallel flue gas single-stage steam superheat compensation and combustion.

[0010] Therefore, the technical solution provided by this invention is as follows:

[0011] A waste heat power generation system for electric furnace flue gas based on parallel flue gas single steam superheat compensation and supplementary combustion includes:

[0012] A parallel flue is installed after the settling chamber and connected to it. The parallel flue includes two flues designed in parallel. One flue contains a steam superheater and forms a steam superheated combustion furnace flue. The other flue contains a tower-shaped flue without a heating surface and forms an empty tower flue.

[0013] The afterburning process takes place in the afterburning furnace flue of the steam superheater.

[0014] Preferably, in the electric furnace flue gas waste heat power generation system based on parallel flue single steam superheat compensation and supplementary combustion, the combustion mode of the supplementary combustion process is a regenerative combustion mode, or biomass fuel is used to replace gaseous fuel for supplementary combustion.

[0015] Preferably, in the electric furnace flue gas waste heat power generation system based on parallel flue single steam superheat compensation and combustion, the two flues are connected and merged into one flue at the outlet of the steam superheat combustion furnace flue.

[0016] Preferably, the electric furnace flue gas waste heat power generation system based on parallel flue gas single steam superheat compensation and supplementary combustion further includes:

[0017] The external circulation system is formed by connecting the parallel flue to the bag filter, and the purified electric furnace flue gas after dust removal by the bag filter is the gas source for the external circulation.

[0018] Preferably, in the electric furnace flue gas waste heat power generation system based on parallel flue single steam superheat compensation and combustion, flue gates are provided at the inlet and outlet of both flues.

[0019] A method for generating electricity from waste heat of electric arc furnace flue gas based on parallel flue gas single steam superheat compensation and supplementary combustion, applied in electric arc furnace steelmaking, includes the following steps:

[0020] The high-temperature electric furnace flue gas from the outlet of the horizontal feeding scrap preheating system is led to the settling chamber for coarse dust removal.

[0021] After coarse dust removal, the electric furnace flue gas is then split into two parallel flues. The parallel flues consist of two flues designed in parallel. One flue contains a steam superheater, forming a steam superheated combustion furnace flue. The other flue contains a tower-shaped flue without heating surfaces, forming an empty tower flue.

[0022] When superheated steam needs to be re-burned and a single regenerative combustion method is used, the flue doors at the inlet and outlet of the steam superheated re-burning furnace are closed, and the steam superheater enters the regenerative combustion re-burning mode. The re-burned flue gas is mixed with the purified electric furnace flue gas after dust removal by the bag filter.

[0023] Preferably, the electric arc furnace flue gas waste heat power generation method based on parallel flue gas single steam superheat compensation and supplementary combustion includes the following steps:

[0024] When it is necessary to supplement the superheated steam, if biomass combustion is used for supplementary combustion, the flue doors at both ends of the inlet and outlet of the steam superheated supplementary combustion furnace are adjusted to close part or all of them, so that the supplementary combustion flue gas and the electric furnace flue gas flow together through the steam superheater to superheat the saturated steam, while the remaining electric furnace flue gas flows through the empty tower flue.

[0025] Preferably, the electric arc furnace flue gas waste heat power generation method based on parallel flue gas single steam superheat compensation and supplementary combustion further includes the following steps:

[0026] The flue gas from the parallel flue is merged into a single flue at the outlet end and then enters the waste heat boiler. In the waste heat boiler, the flue gas temperature drops to 250℃~300℃ after heat exchange with saturated water. After leaving the waste heat boiler, it enters the economizer and exchanges heat with feedwater to cool down to 180℃~200℃. Then, it flows through the condensate preheater and exchanges heat with condensate to cool down to about 120℃. Subsequently, the electric furnace flue gas enters the activated carbon adsorption tower to remove dioxins and then enters the bag filter for dust removal and purification. The purified electric furnace flue gas is then merged with the supplementary combustion flue gas from the single regenerative combustion supplementary combustion furnace and finally discharged into the atmosphere.

[0027] Preferably, in the electric furnace flue gas waste heat power generation method based on parallel flue gas single steam superheat compensation combustion, in the single regenerative combustion mode, the gas does not store heat, only the combustion medium. Single regenerative burners are symmetrically arranged on both sides of the steam superheated combustion furnace. The gas enters the furnace through the gas passage of the single regenerative burner on side A of the steam superheated combustion furnace. Simultaneously, the combustion medium enters the furnace through the heat storage body passage of the single regenerative burner on side A to assist combustion. The combustion medium is preheated to a high temperature by the high-temperature heat storage body when passing through the heat storage body passage. At this time, the heat storage channel of the single regenerative burner on side B of the steam superheated combustion furnace serves as the flue gas duct of the furnace. After exchanging heat with the secondary superheater in the furnace, the high-temperature flue gas is discharged from the combustion furnace. When the high-temperature flue gas flows through the heat storage channel on side B, it heats the heat storage body to a high temperature. At the next moment, the single regenerative burners on both sides switch, that is, the single regenerative burner on side B of the steam superheated combustion furnace switches from the flue gas exhaust state to the heat storage combustion state, and the single regenerative burner on side A of the steam superheated combustion furnace switches from the combustion state to the flue gas exhaust state.

[0028] This invention has at least the following advantages:

[0029] 1) This invention can significantly reduce fuel consumption, with a reduction rate of 20%-40%.

[0030] 2) This invention can reduce flue gas emissions, achieving a total reduction of approximately 10% in flue gas emissions.

[0031] 3) This invention can achieve CO2 emission reduction, with a CO2 emission reduction rate of 10% to 15% compared with existing known electric furnace waste heat power generation technology.

[0032] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0033] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0034] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not imply the presence or addition of one or more other elements or combinations thereof.

[0035] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0036] This invention provides an electric arc furnace flue gas waste heat power generation system based on parallel flue gas single steam superheat compensation and supplementary combustion, comprising:

[0037] A parallel flue is installed after the settling chamber and connected to it. The parallel flue includes two flues designed in parallel. One flue contains a steam superheater and forms a steam superheated combustion furnace flue. The other flue contains a tower-shaped flue without a heating surface and forms an empty tower flue.

[0038] The afterburning process takes place in the afterburning furnace flue of the steam superheater.

[0039] Preferably, in some of the technical solutions of the present invention, the combustion method of the afterburning process is a regenerative combustion method, or biomass fuel is used to replace gaseous fuel for afterburning.

[0040] Preferably, in some technical solutions of the present invention, the two flues are connected and merged into one flue at the outlet of the steam superheated combustion furnace.

[0041] Preferably, some technical solutions of the present invention further include:

[0042] The external circulation system is formed by connecting the parallel flue to the bag filter, and the purified electric furnace flue gas after dust removal by the bag filter is the gas source for the external circulation.

[0043] Preferably, in the above scheme, flue doors are provided at both the inlet and outlet of the two flues.

[0044] This invention also provides a method for generating electricity from waste heat of electric arc furnace flue gas based on parallel flue gas single steam superheat compensation and combustion, applied in electric arc furnace steelmaking, comprising the following steps:

[0045] The high-temperature electric furnace flue gas from the outlet of the horizontal feeding scrap preheating system is led to the settling chamber for coarse dust removal.

[0046] After coarse dust removal, the electric furnace flue gas is then split into two parallel flues. The parallel flues consist of two flues designed in parallel. One flue contains a steam superheater, forming a steam superheated combustion furnace flue. The other flue contains a tower-shaped flue without heating surfaces, forming an empty tower flue.

[0047] When superheated steam needs to be re-burned and a single regenerative combustion method is used, the flue doors at the inlet and outlet of the steam superheated re-burning furnace are closed, and the steam superheater enters the regenerative combustion re-burning mode. The re-burned flue gas is mixed with the purified electric furnace flue gas after dust removal by the bag filter.

[0048] As a preferred embodiment, the above solution also includes the following steps:

[0049] When it is necessary to supplement the superheated steam, if biomass combustion is used for supplementary combustion, the flue doors at both ends of the inlet and outlet of the steam superheated supplementary combustion furnace are adjusted to close part or all of them, so that the supplementary combustion flue gas and the electric furnace flue gas flow together through the steam superheater to superheat the saturated steam, while the remaining electric furnace flue gas flows through the empty tower flue.

[0050] As a preferred embodiment, the above solution also includes the following steps:

[0051] The flue gas from the parallel flue is merged into a single flue at the outlet end and then enters the waste heat boiler. In the waste heat boiler, the flue gas temperature drops to 250℃~300℃ after heat exchange with saturated water. After leaving the waste heat boiler, it enters the economizer and exchanges heat with feedwater to cool down to 180℃~200℃. Then, it flows through the condensate preheater and exchanges heat with condensate to cool down to about 120℃. Subsequently, the electric furnace flue gas enters the activated carbon adsorption tower to remove dioxins and then enters the bag filter for dust removal and purification. The purified electric furnace flue gas is then merged with the supplementary combustion flue gas from the single regenerative combustion supplementary combustion furnace and finally discharged into the atmosphere.

[0052] Preferably, in the above scheme, in the single regenerative combustion method, the gas does not store heat, but only the combustion medium. The single regenerative burners are symmetrically arranged on both sides of the steam superheated combustion furnace. The gas enters the furnace through the gas channel of the single regenerative burner on side A of the steam superheated combustion furnace. At the same time, the combustion medium enters the furnace through the heat storage channel of the single regenerative burner on side A to assist combustion. When the combustion medium passes through the heat storage channel, it is preheated to a high temperature by the high-temperature heat storage body. At this time, the heat storage channel of the single regenerative burner on side B of the steam superheated combustion furnace serves as the flue gas duct of the furnace. After exchanging heat with the secondary superheater in the furnace, the high-temperature flue gas is discharged outside the combustion furnace. When the high-temperature flue gas flows through the heat storage channel on side B, it heats the heat storage body to a high temperature. At the next moment, the single regenerative burners on both sides switch, that is, the single regenerative burner on side B of the steam superheated combustion furnace switches from the flue gas state to the regenerative combustion state, and the single regenerative burner on side A of the steam superheated combustion furnace switches from the combustion state to the flue gas state.

[0053] The following is a further description of the present invention:

[0054] 1. System Structure Improvement Plan

[0055] 1) Improvement of the flue at the steam superheater

[0056] In existing publicly known electric arc furnace flue gas waste heat conventional combustion and superheated steam power generation processes, the single-stage steam superheater located in the settling chamber is improved by placing it in one of the parallel flues following the settling chamber. Specifically, a parallel double-flue structure is designed after the settling chamber. The steam superheater is located in one of the flues (hereinafter referred to as the steam superheated combustion furnace flue), while the other flue is an empty tower flue without heating surfaces. Flue doors are installed at the inlet and outlet of both parallel flues, and the ratio of flue gas volume passing through the two flues can be adjusted by changing the opening of the flue doors. The two parallel flues merge into one flue at the outlet of the steam superheated combustion furnace flue.

[0057] 2) Improved afterburner location

[0058] In the existing known electric arc furnace flue gas waste heat conventional combustion and superheated steam power generation process, the combustion process, which is set in the settling chamber, is improved by placing it in the steam superheater combustion furnace flue in parallel flue, while the empty tower flue connected in parallel does not perform combustion.

[0059] 3) Combustion Improvement

[0060] In existing publicly known electric furnace flue gas waste heat conventional combustion supplementary combustion superheated steam power generation processes, conventional combustion of natural gas is used.

[0061] The method can be improved to regenerative combustion, or biomass fuel can be used to replace gaseous fuel for supplementary combustion. Regenerative combustion allows all the heat released by the supplementary fuel, except for heat loss, to be used to provide superheated heat for steam. When biomass fuel is used to replace gaseous fuel for supplementary combustion, not only can zero carbon emissions be achieved during the supplementary combustion process, but the flue gas parameters (flow rate, temperature) of the electric furnace can also be compensated.

[0062] 4) Improvement of flue gas recirculation method

[0063] In existing conventional combustion and superheated steam power generation processes using waste heat from electric arc furnace flue gas, the burner lacks external flue gas recirculation. This is improved by incorporating external flue gas recirculation into a low-NOx combustion method, with the recirculated gas source being purified electric arc furnace flue gas from a bag filter. This approach not only achieves low-NOx combustion but also fully utilizes the waste heat from the electric arc furnace exhaust, eliminates some residual CO in the flue gas, and reduces total flue gas emissions, further reducing CO2 emissions.

[0064] 2. Control method of the afterburning process of the present invention

[0065] When using gaseous fuel, the afterburning employs a single regenerative combustion method. The control method for the afterburning process in this invention is as follows: When the electric furnace smelting intensity is high, the electric furnace flue gas temperature is high. The steam superheater can superheat the steam to the specified temperature solely relying on the high-temperature waste heat of the electric furnace flue gas. At this time, the afterburning furnace does not perform afterburning, and the flue doors at both ends of the steam superheater afterburning furnace flue are opened, while the flue doors at both ends of the empty tower flue are closed, allowing all electric furnace flue gas to flow through the steam superheater afterburning furnace flue. When the electric furnace smelting intensity is low or during steel tapping, the electric furnace flue gas temperature is low, and the steam superheater cannot superheat the steam to the specified temperature solely relying on the waste heat of the electric furnace flue gas. At this time, the flue doors at both ends of the superheater afterburning furnace flue are closed, while the flue doors on both sides of the empty tower flue are fully opened. The afterburning furnace then performs afterburning to superheat the superheated steam, using the afterburning heat to further increase the steam temperature to the specified temperature. The purpose of using an independent flue for steam superheating is to avoid the problem of excessive afterburning fuel consumption caused by heating a large amount of low-temperature electric furnace flue gas in the existing afterburning process.

[0066] When using biomass fuel, the supplementary combustion adopts a conventional combustion method. The control method of the biomass supplementary combustion process in this invention is as follows: When the electric furnace smelting intensity is high, the electric furnace flue gas temperature is high, and the steam superheater can superheat the steam to the specified temperature simply by relying on the high-temperature waste heat of the electric furnace flue gas. At this time, the supplementary combustion furnace does not perform supplementary combustion, and the flue doors at both ends of the steam superheated supplementary combustion furnace flue are opened and the flue doors at both ends of the empty tower flue are closed, so that all electric furnace flue gas flows through the steam superheated supplementary combustion furnace flue. When the electric furnace smelting intensity is low or during steel tapping, the electric furnace flue gas temperature and flow rate are low, the waste heat boiler has low gas production, and the steam superheater cannot superheat the steam to the specified temperature simply by relying on the waste heat of the electric furnace flue gas. Even when the electric furnace flue gas temperature is at its lowest, back heat transfer may occur. At this time, the flue doors at both ends of the steam superheated supplementary combustion furnace flue are closed and the flue doors on both sides of the empty tower flue are fully opened, and the supplementary combustion furnace performs supplementary combustion. The supplementary combustion is used to compensate for the reduction in electric furnace flue gas temperature and the reduction in superheated steam temperature, maintaining a certain flue gas flow rate and a certain superheated steam temperature at the inlet of the waste heat boiler. The purpose of using parallel flues is to make the steam parameters (evaporation rate, superheated steam temperature and pressure) more flexible and better matched, and to significantly reduce the consumption of low-grade fuel.

[0067] 3. Invention System Workflow

[0068] 1) Electric furnace flue gas process

[0069] High-temperature electric arc furnace (EAF) flue gas from the outlet of the horizontal feeding scrap preheating system is led to the settling dust removal chamber for coarse dust removal via a steam-cooled flue (or insulated flue). After coarse dust removal, the EAF flue gas is then split into two paths and enters the parallel flue. When the EAF smelting intensity is high, superheated steam does not require supplementary combustion. In this case, all EAF flue gas flows through the steam superheated combustion furnace flue and releases heat to the saturated steam before flowing into the waste heat boiler. When the EAF smelting intensity is low, superheated steam needs to be supplemented for combustion. If gaseous fuel is used for supplementary combustion, a single regenerative combustion method is adopted. In this case, the front and rear baffles of the steam superheater flue are closed, and the superheater enters the regenerative combustion supplementary combustion mode. The working principle of the superheated steam regenerative combustion supplementary combustion mode will be explained separately later. The supplementary combustion flue gas is mixed with the purified EAF flue gas after bag filter dust removal. If biomass is used for supplementary combustion, the flue doors at both ends of the steam superheated supplementary combustion furnace are partially or completely closed. A suitable amount of supplementary combustion flue gas flows through the superheater along with the electric furnace flue gas to superheat the saturated steam, while the remaining electric furnace flue gas flows through the empty tower flue. The flue gas from the parallel flue gas merges at the outlet and enters the waste heat boiler. In the waste heat boiler, after exchanging heat with saturated water, the flue gas temperature drops to 250℃~300℃. After leaving the waste heat boiler, the electric furnace flue gas enters the economizer and exchanges heat with feedwater to cool down to 180℃~200℃. Then, it flows through the condensate preheater and exchanges heat with condensate to cool down to about 120℃. Subsequently, the electric furnace flue gas enters the activated carbon adsorption tower to remove dioxins and then enters the bag filter for dust removal and purification. The purified electric furnace flue gas is then merged with the supplementary combustion flue gas from the single regenerative supplementary combustion furnace and finally discharged into the atmosphere through the exhaust fan and chimney.

[0070] 2) Working fluid process

[0071] Condensate from the condenser, along with qualified makeup water, enters the condensate preheater to absorb the low-temperature waste heat from the electric furnace flue gas. It then enters the deaerator for deoxygenation, with the deaerator's gas source being steam flashed from the accumulator. The deaerated water, pressurized by the feedwater pump, enters the economizer to exchange heat with the electric furnace flue gas, utilizing the low-temperature waste heat to preheat the working fluid. Unsaturated water leaving the economizer then enters the waste heat boiler drum. Saturated water from the waste heat boiler drum splits into two streams, flowing through the downcomers into the steam-cooled flue and the waste heat boiler, respectively. In the heating surface tubes of the steam-cooled flue and the waste heat boiler, the saturated water absorbs latent heat of vaporization, forming a steam-water mixture. This mixture then returns to the drum for steam-water separation. The separated saturated water circulates back into the steam-cooled flue and the waste heat boiler for vaporization. The separated saturated steam then enters the accumulator. The low-pressure saturated steam generated in the accumulator enters the steam superheater to absorb superheat. Once the specified superheated temperature is reached, the low-pressure superheated steam then enters the turbine to perform work, driving the generator to produce electricity. After the exhaust steam has done its work, it is condensed in the condenser to form condensate, which then enters the condensate preheater to repeat the above process.

[0072] 3) Working process of a single regenerative combustion afterburning system

[0073] During superheated steam combustion, the dampers in the flue ducts before and after the secondary superheater are closed. The combustion process adopts a single regenerative combustion method, where the gas does not store heat, only the combustion medium. Single regenerative burners are symmetrically arranged on both sides of the combustion furnace (defined as side A and side B). At a certain moment, the gas enters the furnace through the gas passage of the single regenerative burner on side A, while the combustion medium enters the furnace through the regenerator passage of the single regenerative burner on side A. The combustion medium is preheated to a high temperature by the high-temperature regenerator as it passes through the regenerator passage. At this time, the regenerator passage of the single regenerative burner on side B serves as the furnace exhaust flue, where the high-temperature flue gas, after heat exchange with the secondary superheater, is discharged from the combustion furnace. The high-temperature flue gas heats the regenerator to a high temperature as it flows through the regenerator passage on side B. At the next moment, the single regenerative burners on both sides switch: the single regenerative burner on side B switches from exhaust to regenerative combustion, and the single regenerative burner on side A switches from combustion to exhaust. To achieve low-NOx combustion in the afterburner, a low-NOx combustion technology with external flue gas circulation is adopted. The afterburner flue gas discharged from the afterburner is combined with the purified electric furnace flue gas after the bag filter, and then discharged into the atmosphere through the exhaust fan and chimney.

[0074] The number of modules and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0075] Although embodiments of the present invention 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 the present invention. 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, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A waste heat power generation system for electric arc furnace flue gas based on parallel flue gas single steam superheat compensation and combustion, used in steelmaking electric arc furnaces, characterized in that, include: A parallel flue, located after and connected to the settling chamber, comprises two flues designed in parallel. Both flues have flue doors at their inlet and outlet. One flue houses a steam superheater and forms the flue for the steam superheated supplementary combustion furnace. The other flue contains a tower-shaped flue without heating surfaces and forms an empty tower flue. The two flues connect and merge into a single flue at the outlet of the steam superheated supplementary combustion furnace flue. The afterburning process takes place in the flue of the afterburning furnace of the steam superheater, and the combustion method of the afterburning process is regenerative combustion, or biomass fuel is used to replace gaseous fuel for afterburning. The external circulation system is formed by connecting the parallel flue to the bag filter, and the purified electric furnace flue gas after dust removal by the bag filter is the gas source for the external circulation.

2. A method for generating electricity from waste heat of electric arc furnace flue gas based on parallel flue gas single steam superheat compensation and combustion, based on the waste heat power generation system described in claim 1, applied in electric arc furnace steelmaking, characterized in that, Includes the following steps: The high-temperature electric furnace flue gas from the outlet of the horizontal feeding scrap preheating system is led to the settling chamber for coarse dust removal. After coarse dust removal, the electric furnace flue gas is then split into two parallel flues. The parallel flues consist of two flues designed in parallel. One flue contains a steam superheater, forming a steam superheated combustion furnace flue. The other flue contains a tower-shaped flue without heating surfaces, forming an empty tower flue. When it is necessary to supplement the superheated steam and a single regenerative combustion method is used, the flue doors at the inlet and outlet of the steam superheated supplementary combustion furnace are closed, and the steam superheater enters the regenerative combustion supplementary combustion mode. The supplementary combustion flue gas after supplementary combustion is mixed with the purified electric furnace flue gas after dust removal by the bag filter. In the single regenerative combustion mode, the gas does not store heat, only the combustion medium. Single regenerative burners are symmetrically arranged on both sides of the steam superheated combustion furnace. The gas enters the furnace through the gas passage of the single regenerative burner on side A of the steam superheated combustion furnace. At the same time, the combustion medium enters the furnace through the heat storage passage of the single regenerative burner on side A to assist combustion. When the combustion medium passes through the heat storage passage, it is preheated to a high temperature by the high-temperature heat storage body. At this time, the heat storage passage of the single regenerative burner on side B of the steam superheated combustion furnace serves as the flue gas duct of the furnace. After exchanging heat with the secondary superheater in the furnace, the high-temperature flue gas is discharged outside the combustion furnace. When the high-temperature flue gas flows through the heat storage passage on side B, it heats the heat storage body to a high temperature. At the next moment, the single regenerative burners on both sides switch, that is, the single regenerative burner on side B of the steam superheated combustion furnace switches from the flue gas state to the regenerative combustion state, and the single regenerative burner on side A of the steam superheated combustion furnace switches from the combustion state to the flue gas state.

3. The method for generating electricity from waste heat of electric furnace flue gas based on parallel flue gas single steam superheat compensation and supplementary combustion as described in claim 2, characterized in that, Includes the following steps: When it is necessary to supplement the superheated steam, if biomass combustion is used for supplementary combustion, the flue doors at both ends of the inlet and outlet of the steam superheated supplementary combustion furnace are adjusted to close part or all of them, so that the supplementary combustion flue gas and the electric furnace flue gas flow together through the steam superheater to superheat the saturated steam, while the remaining electric furnace flue gas flows through the empty tower flue.

4. The method for generating electricity from waste heat of electric furnace flue gas based on parallel flue gas single steam superheat compensation and supplementary combustion as described in any one of claims 2 or 3, characterized in that, Includes the following steps: The flue gas from the parallel flue is merged into a single flue at the outlet end and then enters the waste heat boiler. In the waste heat boiler, the flue gas temperature drops to 250℃~300℃ after heat exchange with saturated water. After leaving the waste heat boiler, it enters the economizer and exchanges heat with feedwater to cool down to 180℃~200℃. Then, it flows through the condensate preheater and exchanges heat with condensate to cool down to about 120℃. Subsequently, the electric furnace flue gas enters the activated carbon adsorption tower to remove dioxins and then enters the bag filter for dust removal and purification. The purified electric furnace flue gas is then merged with the supplementary combustion flue gas from the single regenerative combustion supplementary combustion furnace and finally discharged into the atmosphere.