Electric furnace flue gas temperature and flow two-parameter self-adaptive control system and method

Abstract

The invention discloses an electric furnace flue gas temperature and flow two-parameter self-adaptive control system and method, and belongs to the technical field of electric furnace flue gas waste heat recovery. An inlet of the waste heat boiler is connected with a smoke settling chamber connected with an electric furnace through a smoke main flue, and an outlet of the waste heat boiler is connected with a dust remover through a smoke exhaust flue. The flue gas flow adjusting system comprises a first flue gas bypass of which an inlet and an outlet are respectively connected with the flue gas main flue and the flue gas discharge flue, and a circulating flue of which an inlet is connected with the flue gas discharge flue and an outlet is connected with the upstream of the fused salt heater; the fused salt heat storage system comprises a first fused salt heat accumulator in the flue gas settling chamber, a first fused salt tank and a second fused salt tank outside the flue gas settling chamber, a second flue gas bypass on the flue gas main flue and a fused salt heater in the second flue gas bypass, and an inlet and an outlet of the first fused salt heat accumulator are connected with the first fused salt tank and the second fused salt tank; the molten salt heater inlet and outlet are connected with the second and first molten salt tanks. According to the invention, two-parameter self-adaptive stable control of the temperature and the flow of the flue gas entering the waste heat boiler can be realized.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery technology from electric furnace flue gas, and in particular to a dual-parameter adaptive control system and method for electric furnace flue gas temperature and flow rate. Background Technology

[0002] Electric arc furnace (EAF) steelmaking, as a key method in short-process steelmaking, has become a crucial path for the steel industry towards green development amidst the energy revolution focused on carbon peaking and carbon neutrality. This is due to its advantages such as simple processes, low investment costs, short construction periods, and significant energy conservation and emission reduction effects. However, in the EAF steelmaking process, the emission of high-temperature flue gas carries away a large amount of valuable heat energy, and the flue gas parameters fluctuate significantly. This results in traditional waste heat recovery devices only producing intermittent, low-quality saturated steam, making it difficult to improve power generation efficiency. Although some new technologies currently employ supplementary combustion and superheating to achieve superheated steam power generation, this approach requires additional energy consumption, contradicting the original intention of energy conservation.

[0003] Currently, electric arc furnace flue gas waste heat recovery systems mainly consist of core equipment such as vaporization cooling combustion settling chambers, vaporization cooling flues, and convective heat exchangers. These systems mostly rely on steam accumulators to produce continuous steam. However, because the generation of electric arc furnace flue gas is intermittent, the steam pressure and temperature are relatively low, resulting in poor steam quality and limiting its application. Furthermore, as the iron-to-metal ratio gradually increases, the temperature and dust content of the flue gas rise significantly, undoubtedly placing more stringent performance requirements on the auxiliary flue gas cooling and dust removal systems.

[0004] In light of this, researchers have begun to explore new technologies for recovering waste heat from electric furnace flue gas. To address the problems of low power generation efficiency and high energy consumption caused by waste heat from electric furnace flue gas, many current research directions focus on steam generation systems based on molten salt.

[0005] For example, Chinese patent CN207095315U discloses an electric furnace flue gas treatment system, comprising a combustion settling chamber, a high-temperature flue gas treatment section, a low-temperature flue gas treatment section (including a molten salt heater, a steam superheater, a molten salt tank, and molten salt pipelines), a dust removal mechanism, an induced draft fan, and a chimney, connected in sequence. However, the inventors note that this technology directly replaces the waste heat boiler with a full molten salt system, which uses the waste heat of the electric furnace flue gas to produce stable steam through molten salt heat storage, thereby achieving stable steam output. This system is a technology that couples molten salt energy storage with steam generation.

[0006] For example, Chinese patent CN217737920U discloses an electric furnace waste heat boiler system with molten salt superheating. This system includes a low-temperature molten salt tank, a high-temperature molten salt tank, a molten salt flue gas heat exchanger, and a molten salt steam heat exchanger. Through the installation of the molten salt flue gas heat exchanger and the molten salt steam heat exchanger, this system achieves waste heat recovery and steam generation from the waste heat boiler. As another example, Chinese application CN117870386A proposes an electric furnace waste heat recovery system and method based on molten salt thermal storage. This system utilizes high-temperature flue gas from the electric furnace to heat low-temperature molten salt to form high-temperature molten salt, which is then used to heat saturated steam to generate superheated steam. However, the inventors noted that the systems proposed in both documents are optimized from the steam usage side to achieve continuous and stable steam, without mentioning the impact of flue gas flow and temperature fluctuations on the operation of the waste heat boiler itself. In both documents, the temperature usually varies periodically from room temperature to 1000℃, and the flow also fluctuates drastically with the smelting stage. The design needs to be configured according to the peak flue gas load, resulting in the problem of "overpowered power for underpowered systems".

[0007] In summary, the inventor recognizes the following drawbacks of the prior art: 1) The traditional waste heat boiler combined with heat accumulator to produce saturated steam has low power generation efficiency and is difficult to meet the development requirements of high efficiency and energy saving.

[0008] 2) Existing electric furnace flue gas waste heat recovery systems are inadequate in dealing with large fluctuations in flue gas temperature. In order to achieve continuous and stable steam, optimization is generally carried out from the steam usage side, while ignoring the adverse effects of flue gas on the operation of the waste heat boiler body. The waste heat boiler body system has problems such as unstable operation and poor durability.

[0009] 3) Some of the new technologies that use afterburning and superheating consume additional energy, which deviates from the original intention of energy conservation.

[0010] 4) There is still room for further optimization in the structural design of existing molten salt flue gas heat exchangers, and further improvements are needed to fully enhance heat exchange efficiency and durability.

[0011] 5) The system lacks intelligent control and optimization capabilities, cannot achieve dynamic adjustment, and is difficult to achieve precise control. Summary of the Invention

[0012] Based on this, according to one embodiment of the present invention, the objective is to provide an adaptive control system and method for dual parameters of electric furnace flue gas temperature and flow rate. From the perspective of stable operation of the waste heat boiler body (i.e., steam production side), by adding a molten salt thermal storage system and a flue gas flow regulation system to the electric furnace flue gas waste heat boiler recovery system, adaptive and stable control of dual parameters of temperature and flow rate of the flue gas entering the waste heat boiler is achieved, solving the problem of unstable operation of traditional waste heat boiler bodies.

[0013] The above objective can be achieved through the following technical solutions: According to one aspect of the present invention, a dual-parameter adaptive control system for electric furnace flue gas temperature and flow rate is provided, comprising: The waste heat boiler has its inlet connected to the outlet of the flue gas settling chamber via the main flue gas duct, and its outlet connected to the dust collector via the exhaust flue. The inlet of the flue gas settling chamber is connected to the outlet of the electric furnace. A flue gas flow regulation system includes: a first flue gas bypass and a circulating flue, wherein the inlet and outlet of the first flue gas bypass are connected to the main flue and the exhaust flue, respectively; the inlet of the circulating flue is connected to the exhaust flue, the outlet of the circulating flue is connected to the upstream flue of the molten salt heater, and a circulating fan is provided on the circulating flue. A molten salt thermal storage system includes: a first molten salt accumulator installed in a flue gas settling chamber; a first molten salt tank and a second molten salt tank located outside the flue gas settling chamber; a second flue gas bypass installed on the main flue gas duct; and a molten salt heater located in the second flue gas bypass. The inlet and outlet of the first molten salt accumulator are connected to the first and second molten salt tanks, respectively, for using molten salt in the first molten salt tank to cool the high-temperature flue gas in the flue gas settling chamber; after heating, the molten salt flows back to the second molten salt tank. The inlet and outlet of the molten salt heater are connected to the second and first molten salt tanks, respectively, for using molten salt in the second molten salt tank to heat the diverted flue gas in the second flue gas bypass; after cooling, the molten salt flows back to the first molten salt tank.

[0014] Preferably, the molten salt thermal storage system further includes a second molten salt accumulator disposed in the first flue gas bypass.

[0015] Preferably, the inlet and outlet of the second molten salt accumulator are connected to the first molten salt tank and the second molten salt tank, respectively, for using the molten salt in the first molten salt tank to cool the diverted flue gas in the first flue gas bypass, and after heating, the molten salt flows back to the second molten salt tank.

[0016] Preferably, the first molten salt accumulator is fixedly arranged on the inner wall at the outlet of the flue gas settling chamber.

[0017] Preferably, the outlets of the first molten salt tank and the second molten salt tank are respectively equipped with a first molten salt pump and a second molten salt pump.

[0018] Preferably, the temperature of the molten salt in the first molten salt vessel is ≤260℃; the temperature of the molten salt in the second molten salt vessel is >500℃.

[0019] Preferably, the second molten salt accumulator is arranged in a tubular configuration within the first flue gas bypass.

[0020] Preferably, the molten salt heater is arranged in a spiral channel structure within the second flue gas bypass.

[0021] Preferably, the inner walls of the molten salt heater, the first molten salt accumulator, and the second molten salt accumulator are all provided with a high-temperature resistant and wear-resistant coating.

[0022] Preferably, the high-temperature and wear-resistant coating is an Al2O3-TiO2 composite layer.

[0023] Preferably, the system further includes a three-way orientation reversing device for connecting each flue and automatically adjusting the opening degree through an electric adjustment mechanism to control the flue gas diversion ratio.

[0024] Preferably, the system further includes: an intelligent control system for dynamically adjusting the flue gas diversion ratio based on real-time monitored data.

[0025] Preferably, the intelligent control system includes: a temperature sensor, a flow sensor, a data acquisition module, and an intelligent processor; The temperature sensors are located at the electric furnace outlet flue, the flue gas settling chamber, the inlet and outlet of the first molten salt accumulator, the inlet and outlet of the second molten salt accumulator, the inlet and outlet of the molten salt heater, and the inlet side of the waste heat boiler. The flow sensor is installed on the flue of the main flue gas duct, the first flue gas bypass, and the second flue gas bypass. The data acquisition module is connected to each temperature sensor and each flow sensor to collect temperature and flow data in real time. The intelligent processor is connected to the data acquisition module and is used to optimize the flue gas diversion ratio based on the acquired data, so as to dynamically adjust the flue gas diversion ratio according to the optimized flue gas diversion ratio.

[0026] Preferably, the system further includes: a main exhaust fan connected to the dust collector outlet and a chimney connected to the main exhaust fan.

[0027] Preferably, the system further includes an induced draft fan located upstream of the dust collector.

[0028] According to another aspect of the present invention, a dual-parameter adaptive control method for electric furnace flue gas temperature and flow rate is provided. During the process of electric furnace flue gas entering the flue gas settling chamber for settling and then entering the waste heat boiler, the method includes: adjusting and maintaining the stability of the flue gas flow rate entering the waste heat boiler through a flue gas flow rate regulation system; and adjusting and maintaining the stability of the flue gas temperature entering the waste heat boiler through a molten salt heat storage system. The step of regulating and maintaining a stable flow of flue gas into the waste heat boiler through a flue gas flow regulation system includes: when the electric furnace flue gas flow is ≥150,000 Nm³ / h 3 When the flow rate is / h, the first flue gas bypass is opened, diverting a portion of the flue gas in the main flue gas duct to the first flue gas bypass, thereby reducing the flue gas flow rate in the main flue gas duct to <150,000 Nm³. 3After passing through the waste heat boiler, the diverted flue gas in the first flue gas bypass is cooled by the second molten salt accumulator and then enters the dust collector, where it is discharged after dust removal. When the electric furnace flue gas flow rate is ≤130,000 Nm³ / h... 3 When the temperature reaches 100°C / h, start the circulating fan so that the flue gas discharged from the waste heat boiler is sent back to the inlet of the waste heat boiler through the circulating flue and then heated to the set temperature by the molten salt heater in the second flue gas bypass before entering the waste heat boiler. The steps of regulating and maintaining a stable temperature of flue gas entering the waste heat boiler through the molten salt heat storage system include: when the electric furnace flue gas temperature is ≥550℃, molten salt in the first molten salt tank enters the first molten salt heat storage tank and exchanges heat with the high-temperature flue gas in the flue gas settling chamber. After the high-temperature flue gas is cooled to the set temperature, it enters the waste heat boiler through the main flue gas duct; when the electric furnace flue gas temperature is ≤500℃, the second flue gas bypass is opened, so that the flue gas in the main flue gas duct is diverted to the second flue gas bypass, and then heated to the set temperature by the molten salt heater before entering the waste heat boiler.

[0029] Preferably, the set temperature of the flue gas entering the waste heat boiler is 500℃-550℃.

[0030] Preferably, after the molten salt in the first molten salt tank exchanges heat with the high-temperature flue gas in the flue gas settling chamber, the molten salt is heated to 550℃-750℃.

[0031] Preferably, the diverted flue gas in the first flue gas bypass is cooled to ≤270°C by the second molten salt accumulator.

[0032] Preferably, the method further includes: real-time monitoring of the flue gas temperature at the electric furnace outlet flue, the flue gas settling chamber, the inlet and outlet of the first molten salt accumulator, the inlet and outlet of the second molten salt accumulator, the inlet and outlet of the molten salt heater, and the inlet side of the waste heat boiler.

[0033] Preferably, the method further includes: real-time monitoring of flue gas flow rates in the main flue gas duct, the first flue gas bypass, and the second flue gas bypass.

[0034] Preferably, the method further includes: collecting real-time monitored temperature and flow data, and optimizing the flue gas diversion ratio based on the collected data; Preferably, the method further includes: dynamically adjusting the flue gas diversion ratio according to the optimized flue gas diversion ratio.

[0035] Compared with the prior art, the present invention has the following beneficial effects: 1) By adding a molten salt thermal storage system and a flue gas flow regulation system before the inlet of the waste heat boiler in the waste heat recovery system, real-time adaptive and stable control of the flow rate and temperature entering the waste heat boiler can be achieved. The flue gas temperature entering the waste heat boiler can be maintained within the ideal range, and the temperature fluctuation can be controlled within ±50°C and the flow fluctuation can be controlled within ±10%, which effectively solves the problem of unstable operating conditions of traditional waste heat boilers.

[0036] 2) All new systems in this invention are installed in bypass mode, allowing for direct disconnection in case of a fault, without affecting the normal operation of the original system. This invention uses molten salt as the heat storage medium, allowing for multiple cycles after a single filling, reducing dependence on external energy sources and lowering operating costs.

[0037] 3) By combining dual-tank molten salt heat storage with flue gas bypass diversion, the stability adjustment requirements of flue gas entering the waste heat boiler under different flow rates and temperatures are met. At the same time, it overcomes the problems of large molten salt volume, large footprint, high cost, low efficiency of waste heat boiler due to large amount of molten salt exchanging heat with flue gas, inability to generate more saturated steam, and heat release of molten salt to the outside world that exist when all steam is superheated.

[0038] By using dual-tank molten salt thermal storage technology, a wide temperature regulation range for flue gas is achieved, thereby improving thermal energy utilization efficiency.

[0039] 4) By setting up an intelligent control system, the automatic flue gas diversion is combined with real-time online monitoring of the flue gas. Based on the real-time monitored flue gas parameters (temperature, flow rate) and the temperature of each stage of the molten salt, the flue gas diversion ratio is dynamically adjusted, thereby achieving precise control of the temperature and flow rate of the flue gas entering the waste heat boiler. Moreover, the system of this invention is more flexible in operation, requires less investment, occupies less space, and has less impact on the original waste heat recovery process.

[0040] 5) This invention can maintain the stability of flue gas parameters at the inlet of the waste heat boiler under the condition of electric furnace load fluctuation of ±30%, and improve the overall energy utilization efficiency by 8-12%, thus effectively solving the problems of high energy consumption and low efficiency in the prior art. Attached Figure Description

[0041] Figure 1 This is the process flow of a dual-parameter adaptive control system for electric furnace flue gas temperature and flow rate according to an embodiment of the present invention.

[0042] Figure reference numerals: Electric furnace 1, fourth hole 11, electric furnace flue gas duct 12, flue gas settling chamber 2, waste heat boiler 3, dust collector 4, main exhaust fan 5, chimney 6, main flue gas duct 31, exhaust flue 32, first flue gas bypass 33, second flue gas bypass 34, circulating flue duct 35, circulating fan 36, first molten salt tank 71, second molten salt tank 72, first molten salt pump 73, second molten salt pump 74, first molten salt accumulator 81, second molten salt accumulator 82, molten salt heater 83, three-way orientation reversing device one 91, three-way orientation reversing device two 92, three-way orientation reversing device three 93, three-way orientation reversing device four 94. Detailed Implementation

[0043] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] To address the problems of unstable operation of traditional waste heat boilers, low efficiency of waste heat recovery from electric furnace flue gas, need for additional energy consumption, and poor durability, this invention adds a molten salt thermal storage system and a flue gas flow regulation system to the electric furnace flue gas waste heat recovery system. This achieves real-time adaptive and stable control of the flow rate and temperature of the flue gas entering the waste heat boiler, maintaining the temperature of the flue gas entering the waste heat boiler within the ideal range, controlling temperature fluctuations within ±50°C, and flow fluctuations within ±10%. Furthermore, the new system is set in the bypass, allowing for direct disconnection in case of a fault, without affecting the normal operation of the original system.

[0045] The electric furnace flue gas temperature and flow rate dual-parameter adaptive control system provided by the present invention includes: a waste heat boiler, a flue gas flow rate regulation system and a molten salt thermal storage system.

[0046] The inlet and outlet of the waste heat boiler are connected to the flue gas settling chamber and dust collector via the main flue gas duct and exhaust flue, respectively. The waste heat boiler recovers waste heat from the electric furnace flue gas and produces saturated steam. Note: In this invention, "inlet and outlet" refer to both the inlet and outlet.

[0047] The flue gas flow rate is regulated and maintained stably by a flue gas flow rate regulation system. The flue gas flow rate regulation system includes a first flue gas bypass and a circulating flue. The inlet and outlet of the first flue gas bypass are connected to the main flue gas duct and the exhaust flue, respectively. The inlet of the circulating flue is connected to the exhaust flue, and the outlet is connected to the upstream of the molten salt heater.

[0048] The molten salt thermal storage system regulates and maintains a stable flue gas temperature entering the waste heat boiler. The molten salt thermal storage system includes a first molten salt accumulator, a second molten salt accumulator, a first molten salt tank, a second molten salt tank, a second flue gas bypass located on the main flue gas duct, and a molten salt heater. The first molten salt accumulator is located in the flue gas settling chamber, while the first and second molten salt tanks are located outside the flue gas settling chamber. The inlet and outlet of the first molten salt accumulator are connected to the first and second molten salt tanks, respectively. The molten salt heater is located in the second flue gas bypass, and its inlet and outlet are connected to the second and first molten salt tanks, respectively. The inlet and outlet of the second molten salt accumulator are connected to the first and second molten salt tanks, respectively.

[0049] This invention achieves stable operation of the waste heat boiler and improves the efficiency of waste heat recovery from electric furnace flue gas by adaptively adjusting the temperature and flow rate of the flue gas entering the waste heat boiler, i.e., the flue gas at the inlet side of the waste heat boiler.

[0050] Figure 1 The schematic diagram illustrates the process flow of a dual-parameter adaptive control system for electric furnace flue gas temperature and flow rate provided in one embodiment of the present invention. (Reference) Figure 1 As shown, the system includes: an electric furnace, a flue gas settling chamber 2, a waste heat boiler 3, a dust collector 4, a main exhaust fan 5, a flue gas chimney 6, and a flue gas flow regulation system and a molten salt heat storage system, connected in sequence.

[0051] The furnace cover of electric furnace 1 is specially equipped with a flue gas discharge channel, namely the fourth hole 11. The fourth hole is connected to the inlet end of the flue gas settling chamber 2 through the electric furnace flue gas duct 12. The outlet of the flue gas settling chamber 2 is connected to the flue gas inlet of the waste heat boiler 3 through the main flue gas duct 31. The waste heat boiler 3 generates saturated steam. After heat exchange in the waste heat boiler 3, the flue gas enters the dust collector 4 through the exhaust flue duct 32 for dust removal. After dust removal, it is discharged into the external environment through the main exhaust fan 5 and the chimney 6. Further, preferably, an induced draft fan can also be installed upstream of the dust collector 4 to enhance the exhaust rate by providing a slightly negative pressure environment.

[0052] A second flue gas bypass 34, a first flue gas bypass 33, and a recirculation flue 35 are provided on the main flue gas duct 31. The first flue gas bypass 33 and the recirculation flue 35 are mainly used for flue gas flow regulation and control, serving as components in the flue gas flow regulation system; while the second flue gas bypass 34 is mainly used for temperature regulation and control after flue gas diversion, thus serving as a component in the molten salt thermal storage system.

[0053] The inlet of the first flue gas bypass 33 is connected to the main flue gas duct 31, and the outlet is connected to the exhaust flue duct 32, so as to realize the diversion of flue gas in the main flue gas duct 31.

[0054] The inlet and outlet of the circulating flue 35 are connected to the exhaust flue 32 and the main flue 31, respectively, to circulate the flue gas discharged from the waste heat boiler 3 to the inlet of the waste heat boiler 3 to increase the flow rate. A circulating fan 36 is installed on the circulating flue 35.

[0055] More preferably, the outlet of the circulating flue 35 is located on the flue upstream of the molten salt heater 83, which can be the second flue gas bypass 34 or the main flue gas duct 31, so that the flue gas is heated by the molten salt heater 83 and then sent to the waste heat boiler 3, thereby further improving the stable regulation and control of the flue gas temperature.

[0056] Both the first molten salt tank 71 and the second molten salt tank 72 are located outside the flue gas settling chamber 2. The outlets of the first molten salt tank 71 and the second molten salt tank 72 are respectively equipped with a first molten salt pump 73 and a second molten salt pump 74. This invention adds a flue gas flow regulation system and a molten salt heat storage system in the bypass configuration, allowing for direct disconnection in case of a fault without affecting the normal operation of the original system. Initially, the first molten salt tank 71 can be filled with molten salt at a temperature ≤260℃, and the second molten salt tank 72 can be filled with molten salt at a temperature >500℃. This invention's electric furnace flue gas waste heat recovery and utilization is a fuel-free saturated steam superheated power generation technology. It uses molten salt as a heat storage medium, allowing for multiple cycles after a single filling, reducing dependence on external energy sources and lowering operating costs.

[0057] The first molten salt accumulator 81 is installed inside the flue gas settling chamber 2. The inlet and outlet of the first molten salt accumulator 81 are connected to the first molten salt tank 71 and the second molten salt tank 72, respectively. By utilizing the low-temperature molten salt in the first molten salt tank 71 to exchange heat with the high-temperature flue gas in the flue gas settling chamber 2, the high-temperature flue gas is cooled before entering the waste heat boiler 3. The molten salt, after heat exchange and reheating, flows back to the second molten salt tank 72 for storage. Preferably, the first molten salt accumulator 81 is arranged on the inner wall of the flue gas outlet inside the flue gas settling chamber 2 to ensure sufficient heat exchange with the high-temperature flue gas inside.

[0058] Molten salt heater 83 is installed in the second flue gas bypass 34. The inlet and outlet of molten salt heater 83 are connected to the second molten salt tank 72 and the first molten salt tank 71, respectively. By using the high temperature molten salt in the second molten salt tank 72 to exchange heat with the diverted flue gas in the second flue gas bypass 34, the diverted flue gas is heated and then enters the waste heat boiler 3. The molten salt is cooled down after heat exchange and flows back to the first molten salt tank 71.

[0059] Preferably, the molten salt heater 83 adopts a spiral channel structure to increase the heat exchange area and turbulence intensity.

[0060] The second molten salt accumulator 82 is installed in the first flue gas bypass 33. The inlet and outlet of the second molten salt accumulator 82 are connected to the first molten salt tank 71 and the second molten salt tank 72, respectively. The molten salt in the first molten salt tank 71 is used to exchange heat with the diverted flue gas in the first flue gas bypass 33. After the diverted flue gas is cooled down, it enters the dust collector 4. After the molten salt is heated up by heat exchange, it flows back to the second molten salt tank 72.

[0061] Preferably, the second molten salt accumulator 82 is arranged in a tubular configuration within the flue of the first flue gas bypass 33 to ensure sufficient heat exchange.

[0062] Furthermore, the inner walls of the molten salt heater 83 and the two molten salt accumulators are all made of high-temperature and wear-resistant nano-coating materials. In particular, the Al2O3-TiO2 composite coating is used, which improves the heat exchange efficiency by 15-20% and effectively solves the problem of insufficient heat exchange efficiency and durability of molten salt heat exchangers.

[0063] The system also includes an intelligent control system (not shown) for dynamically adjusting the flue gas diversion ratio based on real-time monitoring data, thereby achieving more precise dynamic control of the temperature and flow rate of the flue gas entering the waste heat boiler 3.

[0064] Preferably, the intelligent control system includes: a temperature sensor, a flow sensor, a data acquisition module, and an intelligent processor. The temperature sensor is installed in the front flue, settling chamber, inlet and outlet of each molten salt heat exchanger, and on the flue gas inlet side of the waste heat boiler 3. The flow sensor is installed in the main flue gas duct 31 and the flue gas bypass duct. The data acquisition module is connected to each sensor to collect temperature and flow data in real time. The intelligent processor is connected to the data acquisition module and is used to optimize the flue gas diversion ratio based on the real-time collected data using algorithms; thus, the flue gas diversion ratio can be dynamically adjusted according to the optimized ratio.

[0065] Furthermore, the various flues in the system are connected by a three-way air intake reversing device, and the opening of the three-way air intake reversing device is adjusted by an electric adjustment mechanism to achieve flue gas diversion control.

[0066] like Figure 1 As shown, a three-way air intake reversing device 91 is installed on the main flue gas duct 31 and leads out to the first flue gas duct. Two three-way air intake reversing devices 92 and 93 are sequentially installed on the first flue gas duct, leading out to the second flue gas bypass 34 and connecting to the outlet of the circulating flue gas duct 35. A three-way air intake reversing device 94 is installed on the first flue gas bypass 33 downstream of the second molten salt accumulator 82 and connects to the inlet of the circulating flue gas duct 35.

[0067] By installing three-way air intake reversing devices with automatically adjustable openings in the main flue gas duct 31 and the bypass flue gas duct, and adjusting their openings through an electric adjustment mechanism, precise control of flue gas flow rate is achieved. Furthermore, by connecting with an intelligent control system, dynamic control of the flue gas diversion ratio is realized.

[0068] The following combines the system and Figure 1 The adaptive control process for dual parameters of electric furnace flue gas temperature and flow rate is explained below: The flue gas discharged from the electric furnace enters the flue gas settling chamber 2 for settling. After settling, the flue gas enters the waste heat boiler 3. During this process, the present invention regulates and maintains the stability of the flue gas flow rate entering the waste heat boiler 3 through the flue gas flow rate regulation system and regulates and maintains the stability of the flue gas temperature entering the waste heat boiler 3 through the molten salt heat storage system. By regulating and controlling the temperature and flow rate of the flue gas entering the waste heat boiler 3, the internal operating stability of the waste heat boiler 3 is improved, and the waste heat recovery efficiency of the electric furnace flue gas is improved.

[0069] Flue gas flow rate adjustment: When the flue gas flow rate of the electric furnace is high, such as 150,000 Nm³, 3 / h-200,000 Nm 3 At a flow rate of / h, the first flue gas bypass 33 opens, diverting the flue gas flow rate in the main flue gas duct 31 to an optimal ratio, reducing the flue gas flow rate in the main flue gas duct 31 to 130,000 Nm³. 3 / h-150,000 Nm 3 / h, this part of the flue gas enters the waste heat boiler 3 through the main flue gas duct 31, while the diverted flue gas first passes through the second molten salt accumulator 82 arranged in the first flue gas bypass 33 to store heat and cool down to ≤270℃, and then enters the dust collector 4 for dust removal. After dust removal, it is discharged to the outside. The molten salt in the second molten salt accumulator 82 is heated and then enters the second molten salt tank 72.

[0070] When the flue gas flow rate of the electric furnace is low, for example 50,000 Nm³ 3 / h-130,000 Nm 3 When the temperature reaches 100°C, the circulating fan 36 is started. Under the action of the circulating fan 36, the flue gas discharged from the waste heat boiler 3 is sent back to the molten salt heater 83 at the boiler inlet through the circulating flue 35 and heated to the set temperature. If it is heated to 500°C-550°C, it will then enter the waste heat boiler 3 to participate in heat exchange. Meanwhile, in the molten salt heater 83, the temperature of the molten salt decreases and flows to the first molten salt tank 71.

[0071] Flue gas temperature regulation: When the electric furnace flue gas temperature is high, such as 550℃-1200℃, the low-temperature molten salt ≤260℃ in the first molten salt tank 71 enters the first molten salt accumulator 81 through the first molten salt pump 73, and exchanges heat with the high-temperature flue gas in the flue gas settling chamber 2. After the flue gas temperature drops to the design temperature, such as 500℃-550℃, it enters the main flue gas duct 31 and enters the waste heat boiler 3 through the main flue gas duct 31. After heat exchange, the molten salt is heated to 550℃-750℃ and flows into the second molten salt tank 72 for storage.

[0072] In electric furnace production, high flue gas temperature is often accompanied by a large flue gas flow rate. A second molten salt accumulator 82 is arranged in the first flue gas bypass 33, and a portion of the molten salt participates in the heat storage of this diverted flue gas.

[0073] When the temperature of the electric furnace flue gas is low, such as 300℃-500℃, the flue gas is diverted to the second flue gas bypass 34. The second molten salt pump 74 pumps the high-temperature molten salt stored in the second molten salt tank 72 into the molten salt heater 83. The molten salt heater 83 uses the high-temperature molten salt to heat this part of the low-temperature diverted flue gas. After the low-temperature flue gas is heated to the set temperature, it enters the waste heat boiler 3. Meanwhile, the temperature of the molten salt in the molten salt heater 83 decreases and flows back to the first molten salt tank 71.

[0074] In the aforementioned flue gas flow and temperature regulation processes, the flue gas diversion is automatically adjusted and controlled by the three-way air intake reversing device according to the optimized flue gas diversion ratio. This results in more precise regulation of both flue gas flow and temperature parameters, further improving the internal operational stability of the waste heat boiler. This invention maintains the stability of the inlet flue gas parameters of the waste heat boiler even with electric furnace load fluctuations of ±30%, while simultaneously improving overall energy utilization efficiency by 8-12%, effectively solving the problems of high energy consumption and low efficiency in existing technologies.

[0075] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A double parameter adaptive control system for temperature and flow of flue gas of an electric furnace, characterized in that, The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system.

2. The electric furnace flue gas temperature and flow double parameter adaptive control system according to claim 1, characterized in that, The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system.

3. The dual parameter adaptive control system for temperature and flow of flue gas of an electric furnace according to claim 2, characterized in that, The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system.

4. The dual parameter adaptive control system for temperature and flow of flue gas of an electric furnace according to claim 2, characterized in that, The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system.

5. The dual parameter adaptive control system for temperature and flow of flue gas of an electric furnace according to claim 2, characterized in that, The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system.

6. The dual parameter adaptive control system for temperature and flow of flue gas of an electric furnace according to claim 2, characterized in that, The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. The application relates to a molten salt heat storage system for a molten salt heat storage system of a molten salt heat storage system. 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7. The dual parameter adaptive control system for temperature and flow rate of flue gas of electric furnace according to claim 2, characterized in that, Further comprising: A main exhaust fan connected with the dust remover outlet and a chimney connected with the main exhaust fan; And / or, further comprising: an induced draft fan arranged upstream of the dust remover.

8. A control method of the electric furnace flue gas temperature and flow double parameter adaptive control system according to any one of claims 2 to 7, characterized in that, In the process that the flue gas of the electric furnace enters the flue gas settling chamber for settling and then enters the waste heat boiler, comprising: adjusting and maintaining the stability of the flue gas flow entering the waste heat boiler through the flue gas flow adjusting system; adjusting and maintaining the stability of the flue gas temperature entering the waste heat boiler through the molten salt heat storage system; wherein, In the step of adjusting and maintaining the stability of the flue gas flow entering the waste heat boiler through the flue gas flow adjusting system, comprising: When the flow of flue gas of the electric furnace is ≥150,000 Nm 3 / h, open the first flue gas bypass, divert part of the flue gas in the main flue to the first flue gas bypass, reduce the flow of flue gas in the main flue to <150,000 Nm 3 / h, then enter the waste heat boiler, the diverted flue gas in the first flue gas bypass enters the dust collector after being cooled by the second molten salt regenerator, and is discharged after being dedusted; When the electric furnace flue gas flow is less than or equal to 130,000 Nm 3 / h, the circulating fan is started, the flue gas discharged from the waste heat boiler is sent back to the inlet of the waste heat boiler through the circulating flue, and then enters the waste heat boiler after being heated to the set temperature by the molten salt heater in the second flue gas bypass. In the step of adjusting and maintaining the stability of the flue gas temperature entering the waste heat boiler through the molten salt heat storage system, comprising: When the flue gas temperature of the electric furnace is ≥550℃, the molten salt in the first molten salt tank enters the first molten salt heat storage device and exchanges heat with the high-temperature flue gas in the flue gas settling chamber, and the high-temperature flue gas is cooled to a set temperature and then enters the waste heat boiler through the main flue gas duct; When the flue gas temperature of the electric furnace is ≤500℃, the second flue gas bypass is opened, the flue gas in the main flue gas duct is shunted to the second flue gas bypass, and the shunted flue gas is heated to a set temperature by the molten salt heater and then enters the waste heat boiler.

9. The control method according to claim 8, characterized by, The set temperature of the flue gas entering the waste heat boiler is 500℃-550℃; After the molten salt in the first molten salt tank exchanges heat with the high-temperature flue gas in the flue gas settling chamber, the molten salt is heated to 550℃-750℃; The shunted flue gas in the first flue gas bypass is cooled to ≤270℃ by the second molten salt heat storage device.

10. The control method according to claim 8, characterized by Further comprising: Real-time monitoring of the flue gas temperature at the outlet flue of the electric furnace, in the flue gas settling chamber, at the inlet and outlet of the first molten salt heat storage device, at the inlet and outlet of the second molten salt heat storage device, at the inlet and outlet of the molten salt heater, and at the inlet side of the waste heat boiler; Real-time monitoring of the flue gas flow in the main flue gas duct, the first flue gas bypass and the second flue gas bypass; Collecting the real-time monitored temperature and flow data, and optimizing the flue gas shunting ratio according to the collected data; According to the optimized flue gas shunting ratio, dynamically adjusting the flue gas shunting ratio.

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