Process method and system based on industrial furnace cascade efficient waste heat recovery

Abstract

The invention discloses a process method and system based on industrial furnace cascade efficient waste heat recovery, and belongs to the technical field of industrial waste heat recovery. The method comprises the steps that industrial furnace high-temperature flue gas is obtained and introduced into a cascade heat exchanger through a flue gas recovery module for two-stage heat exchange, and high-temperature hot water and low-temperature hot water are obtained; the steam generator is driven by high-temperature hot water to produce steam; the steam, the high-temperature hot water and the low-temperature hot water are respectively conveyed to corresponding terminals for use; for multiple working conditions and multiple furnace bodies, operating parameters of various temperature sections are adjusted in real time through an intelligent control system, and it is ensured that the exhaust gas temperature, the steam pressure and the water temperature are stably matched; the waste heat of the industrial furnace can be converted into steam, high-temperature hot water and low-temperature hot water, the requirements for factory life and production energy are met, and the system has the advantages of being high in energy efficiency, high in adaptability, stable in operation, safe, reliable and the like.

Description

Technical Field

[0001] This invention relates to a process and system for efficient waste heat recovery in industrial furnaces, belonging to the field of industrial waste heat recovery and utilization technology. Background Technology

[0002] Industrial furnaces (such as aluminum alloy solution heat treatment furnaces and forging heating furnaces) are key equipment in the metal processing industry. During operation, they require heating via gas or other methods to achieve process requirements, generating large amounts of high-temperature flue gas, typically ranging from 300 to 1000°C. Currently, most companies treat this high-temperature flue gas from industrial furnaces by directly discharging it through chimneys. This not only wastes a significant amount of thermal energy but also increases the company's energy costs. Furthermore, direct discharge of high-temperature flue gas also increases environmental thermal pollution.

[0003] On the other hand, domestic water (such as hot water for employee bathrooms, kitchen water, and cleaning water) in and around enterprise factory areas and communities usually needs to be heated and prepared by means of gas boilers, electric heaters, etc. This type of method has high energy consumption, high operating costs, and certain safety hazards.

[0004] While some industrial flue gas waste heat recovery devices exist in the existing technology, there are few dedicated waste heat recovery systems for industrial furnace flue gas characterized by high-temperature exhaust and trace amounts of metal oxide dust. Furthermore, some waste heat recovery systems may disrupt the user's industrial furnace production during malfunctions, repairs, or maintenance. These systems generally suffer from the following drawbacks:

[0005] 1) Waste heat recovery efficiency is low, mostly single-stage heat exchange, which can only recover part of the high-temperature waste heat, and the medium and low temperature waste heat is not effectively utilized.

[0006] 2) The protective structure was not designed to address the characteristics of industrial furnace flue gas containing trace amounts of metal oxide dust, which can easily cause heat exchanger blockage and corrosion, resulting in a short service life for the equipment;

[0007] 3) Moreover, for industrial furnaces that are not continuously maintained and require intermittent maintenance, the thermal characteristics cannot be accurately matched.

[0008] 4) The lack of a precise temperature and pressure control system can easily lead to dew point corrosion (when the flue gas temperature is too low) or unstable hot water / steam supply.

[0009] 5) The recovered waste heat cannot be supplied in stages according to the different temperature requirements of domestic water, resulting in poor adaptability. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a process method and system for efficient waste heat recovery in industrial furnaces, which converts the recovered waste heat into high-temperature hot water, low-temperature hot water and steam to meet the demand for domestic water and steam.

[0011] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0012] In a first aspect, the present invention provides a process method based on efficient waste heat recovery in a cascade manner from an industrial furnace, comprising:

[0013] To obtain high-temperature flue gas generated during the production process of an industrial furnace;

[0014] The high-temperature flue gas is introduced into the cascade heat exchanger module for cascade heat exchange through the high-temperature flue gas recovery module.

[0015] In the cascade heat exchanger module, the high-temperature flue gas is subjected to two-stage heat exchange using a high-temperature heat exchange unit and a low-temperature heat exchange unit to produce high-temperature hot water and low-temperature hot water, respectively.

[0016] High-temperature hot water is stored in a high-temperature hot water storage tank, and low-temperature hot water is stored in a low-temperature hot water storage tank;

[0017] The stored high-temperature hot water is transported to a steam generator, where its heat is used to convert the pure water into steam, and the steam is supplied to the user's main steam pipeline or stored in a steam storage tank.

[0018] The stored high-temperature hot water and low-temperature hot water are supplied to the corresponding water terminals through high-temperature hot water supply pipelines and low-temperature hot water supply pipelines, respectively.

[0019] The system collects temperature, pressure and flow data in real time through an intelligent control terminal, and automatically adjusts the equipment operation status based on the collected data to maintain the flue gas temperature within the set range, the steam pressure stable, and the hot water temperature matching the terminal requirements.

[0020] Furthermore, the acquisition of high-temperature flue gas generated during the industrial furnace production process includes:

[0021] A bypass duct is installed on the original main air duct of the industrial furnace. The bypass duct includes a pre-circulation air duct passage and a post-circulation air duct passage.

[0022] The bypass duct is intelligently switched in or out by controlling the opening and closing of the shut-off valve through PLC control.

[0023] Start the induced draft fan to draw the high-temperature flue gas into the bypass duct and guide it into the cascade heat exchanger module.

[0024] Furthermore, in the cascade heat exchanger module, a two-stage heat exchange is performed on the high-temperature flue gas using a high-temperature heat exchange unit and a low-temperature heat exchange unit to produce high-temperature hot water and low-temperature hot water respectively, including:

[0025] The high-temperature flue gas first enters the high-temperature heat exchange unit and exchanges heat with the cold water in the pipeline, raising the temperature of the cold water to 150-190℃ to become high-temperature hot water, while the flue gas temperature drops to below 150℃.

[0026] After cooling, the flue gas enters the low-temperature heat exchange unit and undergoes secondary heat exchange with the cold water in the pipeline, raising the temperature of the cold water to 50-80℃ to become low-temperature hot water.

[0027] The flue gas after heat exchange is discharged through the exhaust port.

[0028] Furthermore, the high-temperature hot water storage tank is equipped with a temperature sensor and an electric auxiliary heating device, while the low-temperature hot water storage tank is equipped with a liquid level sensor and a water replenishment device.

[0029] Furthermore, the process of delivering high-temperature hot water to the steam generator includes:

[0030] High-temperature hot water is fed from the high-temperature hot water storage tank into the steam generator;

[0031] The pure water in the pure water tank is supplied to the steam generator;

[0032] Pure water is heated using high-temperature hot water to generate saturated steam at 0.8-1.2 MPa;

[0033] After steam is separated from water in the steam drum, it is delivered to the steam storage tank or the user's main steam pipeline.

[0034] Furthermore, the step of supplying high-temperature hot water and low-temperature hot water to the corresponding water terminals through high-temperature hot water supply pipelines and low-temperature hot water supply pipelines, respectively, includes:

[0035] Steam from the steam storage tank is introduced into the preheater at the front end of the high-temperature hot water storage tank to preheat the cold water entering the high-temperature hot water storage tank.

[0036] Thermostatic valves, flow controllers, filters, and pressure stabilizing valves are installed on the high-temperature hot water supply pipeline and the low-temperature hot water supply pipeline respectively to stabilize the outlet water temperature.

[0037] Furthermore, the control via an intelligent control terminal includes:

[0038] Real-time data collection of flue gas inlet temperature, exhaust temperature, steam pressure, hot water temperature, and flow rate;

[0039] When the flue gas temperature is lower than the temperature required for high-temperature hot water heat exchange, the flue gas is controlled to directly enter the low-temperature hot water heat exchange unit or directly discharged into the chimney.

[0040] The system automatically adjusts the operating status of the shut-off valve, induced draft fan, and thermostatic valve to ensure that the flue gas temperature is stable at 110-120℃, the steam pressure is stable at 0.8-1.2MPa, and the hot water temperature matches the terminal requirements.

[0041] Furthermore, the process method also includes safety protection steps, specifically:

[0042] The system is monitored by safety valves, pressure alarm devices, exhaust valves, over-temperature protection devices, anti-dry-burning devices, and fire dampers.

[0043] When the system temperature or pressure exceeds the set threshold, an alarm will be automatically triggered and an emergency shutdown or pressure relief operation will be performed.

[0044] Furthermore, the cascade heat exchanger module adopts a heat pipe heat exchange structure, is made of ND steel, and has a heat exchange area of ​​100-150㎡ for the high-temperature heat exchange unit and 80-120㎡ for the low-temperature heat exchange unit.

[0045] Secondly, the present invention provides a system for efficient waste heat recovery in industrial furnace stages, used to implement the process method for efficient waste heat recovery in industrial furnace stages as described in any of the preceding claims, comprising:

[0046] High-temperature flue gas recovery module, cascade heat exchanger module, steam-hot water preparation module, water supply module, intelligent control terminal and safety protection module;

[0047] The high-temperature flue gas recovery module is connected to the original main air duct of the industrial furnace and is used to draw out the high-temperature flue gas generated by the industrial furnace.

[0048] The stepped heat exchanger module is connected to the high-temperature flue gas recovery module and includes a high-temperature heat exchange unit and a low-temperature heat exchange unit arranged sequentially along the flue gas flow direction. It is used to perform two-stage heat exchange on the high-temperature flue gas to generate high-temperature hot water and low-temperature hot water respectively.

[0049] The steam-hot water preparation module is connected to the cascade heat exchanger module and includes a steam generator, a high-temperature hot water storage tank, and a low-temperature hot water storage tank. The steam generator receives the high-temperature hot water as a heat source and converts pure water into steam. The high-temperature hot water storage tank and the low-temperature hot water storage tank are used to store the high-temperature hot water and low-temperature hot water prepared by the cascade heat exchanger module, respectively.

[0050] The water supply module is connected to the high-temperature hot water storage tank, the low-temperature hot water storage tank, and the steam output end of the steam-hot water preparation module, respectively, and is used to distribute high-temperature hot water, low-temperature hot water, and steam to the corresponding water terminals.

[0051] The intelligent control terminal is electrically connected to the high-temperature flue gas recovery module, the cascade heat exchanger module, the steam-hot water preparation module, and the water supply module, respectively, and is used to collect system operating parameters and automatically adjust the operating status of each module.

[0052] The safety protection module is integrated into the critical pipelines and equipment of the system and is used to perform safety protection operations in case of over-temperature, over-pressure or abnormal operating conditions.

[0053] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0054] 1. High waste heat recovery efficiency: The two-stage heat exchange structure realizes the full-temperature range waste heat recovery from the 300-1000℃ high-temperature flue gas of the industrial furnace to the 110-120℃ exhaust gas, with a waste heat recovery rate of ≥92%, which is more than 35% higher than the traditional single-stage heat exchange, and significantly reduces heat energy waste.

[0055] 2. High adaptability and comprehensive functions: It can simultaneously supply saturated steam (0.8-1.2MPa), high-temperature hot water (150-190℃), and low-temperature hot water (50-80℃), and can accurately match the needs of low-temperature water and production auxiliary steam or high-temperature hot water without the need for additional heating equipment;

[0056] 3. Long equipment life and stable operation: In response to the high temperature flue gas and corrosive media of industrial furnaces, the waste heat recovery equipment and pipeline modules are all corrosion-resistant and high temperature-resistant, effectively solving the problems of blockage and corrosion, and extending the service life of the equipment to 6-8 years; through intelligent closed-loop control, the exhaust gas temperature is ensured to remain stable above the dew point, avoiding low-temperature corrosion and improving the stability of system operation.

[0057] 4. Comprehensive safety protection: Equipped with multiple safety protection components such as over-temperature, over-pressure, low liquid level, and fire prevention, it realizes automatic alarm and emergency handling in abnormal situations, reducing operational risks;

[0058] 5. Significant economic and environmental benefits: It can replace traditional gas boilers and electric heaters for producing hot water and steam. A single industrial furnace can save 300,000-600,000 m³ of natural gas per year and reduce CO2 emissions by 800-1300 tons. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the system principle provided in an embodiment of the present invention. Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0061] Example 1: This example introduces a process method for high-efficiency waste heat recovery in industrial furnaces, including:

[0062] To obtain high-temperature flue gas generated during the production process of an industrial furnace;

[0063] The high-temperature flue gas is introduced into the cascade heat exchanger module for cascade heat exchange through the high-temperature flue gas recovery module.

[0064] In the cascade heat exchanger module, the high-temperature flue gas is subjected to two-stage heat exchange using a high-temperature heat exchange unit and a low-temperature heat exchange unit to produce high-temperature hot water and low-temperature hot water, respectively.

[0065] High-temperature hot water is stored in a high-temperature hot water storage tank, and low-temperature hot water is stored in a low-temperature hot water storage tank;

[0066] The stored high-temperature hot water is transported to a steam generator, where its heat is used to convert the pure water into steam, and the steam is supplied to the user's main steam pipeline or stored in a steam storage tank.

[0067] The stored high-temperature hot water and low-temperature hot water are supplied to the corresponding water terminals through high-temperature hot water supply pipelines and low-temperature hot water supply pipelines, respectively.

[0068] The system collects temperature, pressure and flow data in real time through an intelligent control terminal, and automatically adjusts the equipment operation status based on the collected data to maintain the flue gas temperature within the set range, the steam pressure stable, and the hot water temperature matching the terminal requirements.

[0069] like Figure 1 As shown, the cascade waste heat recovery system for industrial furnaces (such as aluminum alloy solution heat treatment furnaces, forging heating furnaces, metal heat treatment furnaces, etc.) with high-temperature flue gas characteristics provided in this embodiment is particularly suitable for converting recovered waste heat into high-temperature hot water, low-temperature hot water, and steam to meet domestic water and steam demands. The system specifically includes:

[0070] 1. High-temperature flue gas recovery module;

[0071] For the high-temperature flue gas produced by the industrial furnace, a bypass duct is installed at the main flue gas duct, including a pre-circulation duct passage and a post-circulation duct passage. The bypass duct is directly connected to the original main duct of the industrial furnace. The duct is made of high-temperature resistant stainless steel, which can withstand temperatures up to 1000 degrees Celsius. Each bypass duct is equipped with a shut-off valve, which is controlled by a PLC to achieve intelligent cut-in and cut-out. In addition, an induced draft fan is also installed to draw in the high-temperature flue gas from the industrial furnace, which is then discharged from the chimney after heat exchange.

[0072] 2. Heat exchange module;

[0073] It includes a cascade heat exchanger module, which is connected to the bypass duct and is divided into a high-temperature heat exchange unit (heat exchange area 100-150㎡) and a low-temperature heat exchange unit (heat exchange area 80-120㎡) along the flue gas flow direction.

[0074] The heat exchanger is made of ND steel (high corrosion resistance). The cascade heat exchanger is equipped with a flue gas inlet for high-temperature flue gas to enter and a flue gas outlet after heat exchange. Each cascade heat exchange module is externally equipped with a pipeline module for transporting the medium.

[0075] The heat exchanger adopts a heat pipe heat exchange structure, and the heat exchange area is divided into high temperature heat exchange area and low temperature heat exchange area. It is used to recover the high temperature waste heat of high temperature flue gas (300-1000℃) from industrial furnaces and transfer the heat to the steam generator of the steam-hot water preparation module.

[0076] 3. Steam-High Temperature Hot Water Preparation Module;

[0077] The steam-hot water preparation module includes a steam generator, a high-temperature hot water storage tank, a low-temperature hot water storage tank, and a pure water tank;

[0078] 1) Steam generator: Connected to the heat exchanger via pipeline, it absorbs high-temperature waste heat to drive the steam generator to produce saturated steam at 0.8-1.2MPa. The steam is separated by the steam drum (with steam-water separation device) and stored in the steam storage tank or supplied to the customer's main steam pipeline.

[0079] 2) High-temperature hot water storage tank: with a volume of 15-20m³, connected to the heat exchanger via hot water pipeline, used to store high-temperature hot water at 150-190℃. The storage tank is equipped with a temperature sensor and an electric auxiliary heating device (for emergency backup).

[0080] 3) Low-temperature hot water storage tank: with a volume of 5-10m³, connected to the cascade heat exchanger through pipelines, used to store low-temperature hot water at 50-80℃, and the tank is equipped with a liquid level sensor and a water replenishment device.

[0081] 4) Pure water storage tank: It is connected to the steam generator through a pipeline and serves as a steam source. The high-temperature hot water after heat exchange is fed into the steam generator to convert pure water into steam and send it to the steam storage tank or the user's main steam pipeline.

[0082] 4. Medium and low temperature water preparation module;

[0083] The water supply module includes a high-temperature hot water supply pipeline, a low-temperature hot water supply pipeline, a steam generation pipeline, and a water terminal;

[0084] - Steam preheating pipeline: Steam from the steam storage tank is introduced into the preheater at the front end of the high-temperature hot water storage tank to preheat the cold water entering the high-temperature hot water storage tank and improve heat exchange efficiency; in winter, steam can be directly introduced into the heating pipeline to assist in domestic heating.

[0085] - High-temperature hot water supply pipeline: connects the high-temperature hot water storage tank to high-temperature water terminals such as bathrooms and kitchens. The pipeline is equipped with thermostatic valves and flow controllers to ensure that the outlet water temperature is stable at 150-190℃;

[0086] - Low-temperature hot water supply pipeline: connects the low-temperature hot water storage tank to low-temperature water terminals such as handwashing sinks and cleaning water. The pipeline is equipped with a filter device and a pressure stabilizing valve to ensure that the outlet water temperature is stable at 50-80℃.

[0087] 5. Intelligent control terminal;

[0088] The intelligent control module includes a PLC controller, a temperature sensor, a pressure sensor, a flow sensor, and a touch screen display.

[0089] - Temperature sensors: installed at the inlet of the first-stage high-temperature heat exchanger (flue gas temperature), the outlet of the third-stage low-temperature condenser (exhaust gas temperature), the steam storage tank, the high-temperature hot water storage tank, and the low-temperature hot water storage tank, respectively, to collect temperature data in real time;

[0090] - Pressure sensor: installed in steam generators, steam storage tanks and hot water pipelines to collect pressure data in real time;

[0091] - PLC Controller: Electrically connected to flue gas bypass valve, induced draft fan, steam generator, thermostatic valve, flow controller, etc., it automatically adjusts the equipment operation status based on data collected by sensors to ensure that the flue gas temperature is stable at 110-120℃ (to avoid dew point corrosion), the steam pressure is stable at 0.8-1.2MPa, and the hot water temperature is accurately matched to the terminal requirements. The PLC can control and adjust the flue gas for different temperatures. If the flue gas temperature is lower than the flue gas temperature required for high-temperature hot water heat exchange, the flue gas can directly enter the low-temperature hot water heat exchange, avoiding direct discharge into the chimney if the flue gas temperature does not meet the heat exchange conditions for either heat exchange method.

[0092] - Touchscreen display: Used to display system operating parameters (temperature, pressure, flow rate), supporting manual / automatic mode switching and parameter setting.

[0093] 6. Safety protection module;

[0094] The safety protection module includes safety valves and pressure alarm devices for the steam system, exhaust valves and over-temperature protection devices and anti-dry-burning devices for the hot water system, as well as fire dampers for the flue gas passage. When the temperature or pressure within the system exceeds a set threshold, the safety protection module automatically triggers an alarm and performs emergency shutdown / pressure relief operations to ensure system safety. Furthermore, this heat exchange system is based on the premise of stable operation of the industrial furnace and operates independently, without affecting the user's normal production.

[0095] The working principle of this system is as follows:

[0096] The core principle of this system is "staged waste heat extraction from flue gas - precise energy conversion - differentiated water supply - intelligent closed-loop control". Through the coordinated operation of multiple modules, it achieves efficient recovery of waste heat from high-temperature flue gas in industrial furnaces and a stable supply of domestic water. The specific working mechanism unfolds in six stages, with each stage seamlessly connected to form a complete closed-loop operation:

[0097] After the industrial furnace starts production, it generates high-temperature flue gas. The PLC intelligent control opens the shut-off valve of the bypass duct of the high-temperature flue gas recovery module, and the induced draft fan starts to draw in the high-temperature flue gas, so that the flue gas enters the cascade heat exchanger of the heat exchange module through the bypass duct.

[0098] 1) The high-temperature flue gas first enters the high-temperature heat exchange unit of the cascade heat exchanger for primary heat exchange: the ambient temperature tap water supplied by the user to the low-temperature hot water storage tank is then pumped to the high-temperature heat exchange unit pipeline, where it quickly absorbs the high-temperature waste heat in the flue gas. The tap water in the pipeline is heated to 150-190℃ to become high-temperature hot water, which is then transported to the high-temperature hot water storage tank for storage. During this process, the temperature of the high-temperature flue gas drops from 300-1000℃ to less than 150℃.

[0099] 2) After being cooled down by the first-stage heat exchange, the flue gas at 200-250℃ enters the low-temperature heat exchange unit of the cascade heat exchanger for secondary heat exchange: the cold water in the pipeline absorbs the waste heat of the flue gas and is heated to 50-80℃ to become low-temperature hot water, which is then transported to the low-temperature hot water storage tank for storage.

[0100] 3) Operation of the steam-hot water preparation module: The high-temperature hot water in the high-temperature hot water storage tank is fed into the steam generator to heat the pure water supplied by the pure water tank, so that the pure water is converted into saturated steam at 0.8-1.2MPa; the saturated steam is separated into steam and water in the steam drum and then stored in the steam storage tank or directly supplied to the user's main steam pipeline.

[0101] Steam and hot water can be produced in both directions: In addition to heating and producing steam, high-temperature hot water can also be independently converted into warm air or hot water circulation for heating through a heat exchanger.

[0102] 4) Low-temperature water supply: The low-temperature hot water in the low-temperature storage tank after the secondary low-temperature heat exchange can be transported to the bathroom, kitchen and other terminals for effective use through the low-temperature hot water supply pipeline;

[0103] 5) Intelligent control and safety protection: The intelligent control module collects system temperature, pressure and flow data in real time, and automatically adjusts the opening of the shut-off valve, the speed of the induced draft fan and the status of the thermostatic valve through the PLC controller to ensure the stable operation of the system; the safety protection module monitors the entire process and automatically triggers alarms and emergency handling operations when abnormalities such as over-temperature, over-pressure, or low liquid level occur.

[0104] Compared with the prior art, this embodiment has the following beneficial effects:

[0105] 1. High waste heat recovery efficiency: The two-stage heat exchange structure realizes the full-temperature range waste heat recovery from the 300-1000℃ high-temperature flue gas of the industrial furnace to the 110-120℃ exhaust gas, with a waste heat recovery rate of ≥92%, which is more than 35% higher than the traditional single-stage heat exchange, and significantly reduces heat energy waste.

[0106] 2. High adaptability and comprehensive functions: It can simultaneously supply saturated steam (0.8-1.2MPa), high-temperature hot water (150-190℃), and low-temperature hot water (50-80℃), and can accurately match the needs of low-temperature water and production auxiliary steam or high-temperature hot water without the need for additional heating equipment;

[0107] 3. Long equipment life and stable operation: In response to the high temperature flue gas and corrosive media of industrial furnaces, the waste heat recovery equipment and pipeline modules are all corrosion-resistant and high temperature-resistant, effectively solving the problems of blockage and corrosion, and extending the service life of the equipment to 6-8 years; through intelligent closed-loop control, the exhaust gas temperature is ensured to remain stable above the dew point, avoiding low-temperature corrosion and improving the stability of system operation.

[0108] 4. Comprehensive safety protection: Equipped with multiple safety protection components such as over-temperature, over-pressure, low liquid level, and fire prevention, it realizes automatic alarm and emergency handling in abnormal situations, reducing operational risks;

[0109] 5. Significant economic and environmental benefits: It can replace traditional gas boilers and electric heaters for producing hot water and steam. A single industrial furnace can save 300,000-600,000 m³ of natural gas per year and reduce CO2 emissions by 800-1300 tons.

[0110] Example 2: This example provides a system for efficient waste heat recovery in an industrial furnace using a cascade method, comprising:

[0111] High-temperature flue gas recovery module, cascade heat exchanger module, steam-hot water preparation module, water supply module, intelligent control terminal and safety protection module;

[0112] The high-temperature flue gas recovery module is connected to the original main air duct of the industrial furnace and is used to draw out the high-temperature flue gas generated by the industrial furnace.

[0113] The stepped heat exchanger module is connected to the high-temperature flue gas recovery module and includes a high-temperature heat exchange unit and a low-temperature heat exchange unit arranged sequentially along the flue gas flow direction. It is used to perform two-stage heat exchange on the high-temperature flue gas to generate high-temperature hot water and low-temperature hot water respectively.

[0114] The steam-hot water preparation module is connected to the cascade heat exchanger module and includes a steam generator, a high-temperature hot water storage tank, and a low-temperature hot water storage tank. The steam generator receives the high-temperature hot water as a heat source and converts pure water into steam. The high-temperature hot water storage tank and the low-temperature hot water storage tank are used to store the high-temperature hot water and low-temperature hot water prepared by the cascade heat exchanger module, respectively.

[0115] The water supply module is connected to the high-temperature hot water storage tank, the low-temperature hot water storage tank, and the steam output end of the steam-hot water preparation module, respectively, and is used to distribute high-temperature hot water, low-temperature hot water, and steam to the corresponding water terminals.

[0116] The intelligent control terminal is electrically connected to the high-temperature flue gas recovery module, the cascade heat exchanger module, the steam-hot water preparation module, and the water supply module, respectively, and is used to collect system operating parameters and automatically adjust the operating status of each module.

[0117] The safety protection module is integrated into the critical pipelines and equipment of the system and is used to perform safety protection operations in case of over-temperature, over-pressure or abnormal operating conditions.

[0118] The specific functions of each module described above are explained in the relevant content of the method in Embodiment 1, and will not be repeated here.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process method based on high-efficiency waste heat recovery in industrial furnaces, characterized in that, include: To obtain high-temperature flue gas generated during the production process of an industrial furnace; The high-temperature flue gas is introduced into the cascade heat exchanger module for cascade heat exchange through the high-temperature flue gas recovery module. In the cascade heat exchanger module, the high-temperature flue gas is subjected to two-stage heat exchange using a high-temperature heat exchange unit and a low-temperature heat exchange unit to produce high-temperature hot water and low-temperature hot water, respectively. High-temperature hot water is stored in a high-temperature hot water storage tank, and low-temperature hot water is stored in a low-temperature hot water storage tank; The stored high-temperature hot water is transported to a steam generator, where its heat is used to convert the pure water into steam, and the steam is supplied to the user's main steam pipeline or stored in a steam storage tank. The stored high-temperature hot water and low-temperature hot water are supplied to the corresponding water terminals through high-temperature hot water supply pipelines and low-temperature hot water supply pipelines, respectively. The system collects temperature, pressure and flow data in real time through an intelligent control terminal, and automatically adjusts the equipment operation status based on the collected data to maintain the flue gas temperature within the set range, the steam pressure stable, and the hot water temperature matching the terminal requirements.

2. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 1, characterized in that, The acquisition of high-temperature flue gas generated during the industrial furnace production process includes: A bypass duct is installed on the original main air duct of the industrial furnace. The bypass duct includes a pre-circulation air duct passage and a post-circulation air duct passage. The bypass duct is intelligently switched in or out by controlling the opening and closing of the shut-off valve through PLC control. Start the induced draft fan to draw the high-temperature flue gas into the bypass duct and introduce it into the cascade heat exchanger module.

3. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 2, characterized in that, In the cascade heat exchanger module, a high-temperature heat exchange unit and a low-temperature heat exchange unit are used to perform two-stage heat exchange on the high-temperature flue gas to produce high-temperature hot water and low-temperature hot water, respectively, including: The high-temperature flue gas first enters the high-temperature heat exchange unit and exchanges heat with the cold water in the pipeline, raising the temperature of the cold water to 150-190℃ to become high-temperature hot water, while the flue gas temperature drops to below 150℃. After cooling, the flue gas enters the low-temperature heat exchange unit and undergoes secondary heat exchange with the cold water in the pipeline, raising the temperature of the cold water to 50-80℃ to become low-temperature hot water. The flue gas after heat exchange is discharged through the exhaust port.

4. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 3, characterized in that, The high-temperature hot water storage tank is equipped with a temperature sensor and an electric auxiliary heating device, while the low-temperature hot water storage tank is equipped with a liquid level sensor and a water replenishment device.

5. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 4, characterized in that, The process of delivering high-temperature hot water to a steam generator includes: High-temperature hot water is fed from the high-temperature hot water storage tank into the steam generator; The pure water in the pure water tank is supplied to the steam generator; Pure water is heated using high-temperature hot water to generate saturated steam at 0.8-1.2 MPa; After steam is separated from water in the steam drum, it is delivered to the steam storage tank or the user's main steam pipeline.

6. The process method based on high-efficiency waste heat recovery in an industrial furnace according to claim 5, characterized in that, The process of supplying high-temperature hot water and low-temperature hot water to water terminals with corresponding temperature requirements through high-temperature hot water supply pipelines and low-temperature hot water supply pipelines, respectively, includes: Steam from the steam storage tank is introduced into the preheater at the front end of the high-temperature hot water storage tank to preheat the cold water entering the high-temperature hot water storage tank. Thermostatic valves, flow controllers, filters, and pressure stabilizing valves are installed on the high-temperature hot water supply pipeline and the low-temperature hot water supply pipeline respectively to stabilize the outlet water temperature.

7. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 1, characterized in that, The regulation via intelligent control terminal includes: Real-time data collection of flue gas inlet temperature, exhaust temperature, steam pressure, hot water temperature, and flow rate; When the flue gas temperature is lower than the temperature required for high-temperature hot water heat exchange, the flue gas is controlled to directly enter the low-temperature hot water heat exchange unit or directly discharged into the chimney. The system automatically adjusts the operating status of the shut-off valve, induced draft fan, and thermostatic valve to ensure that the flue gas temperature is stable at 110-120℃, the steam pressure is stable at 0.8-1.2MPa, and the hot water temperature matches the terminal requirements.

8. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 1, characterized in that, The process method also includes safety protection steps, specifically: The system is monitored by safety valves, pressure alarm devices, exhaust valves, over-temperature protection devices, anti-dry-burning devices, and fire dampers. When the system temperature or pressure exceeds the set threshold, an alarm will be automatically triggered and an emergency shutdown or pressure relief operation will be performed.

9. The process method based on high-efficiency waste heat recovery in industrial furnaces according to claim 1, characterized in that, The cascade heat exchanger module adopts a heat pipe heat exchange structure and is made of ND steel. The heat exchange area of ​​the high-temperature heat exchange unit is 100-150㎡, and the heat exchange area of ​​the low-temperature heat exchange unit is 80-120㎡.

10. A system for efficient waste heat recovery in an industrial furnace, used to implement the process method for efficient waste heat recovery in an industrial furnace as described in any one of claims 1 to 9, characterized in that, include: High-temperature flue gas recovery module, cascade heat exchanger module, steam-hot water preparation module, water supply module, intelligent control terminal and safety protection module; The high-temperature flue gas recovery module is connected to the original main air duct of the industrial furnace and is used to draw out the high-temperature flue gas generated by the industrial furnace. The stepped heat exchanger module is connected to the high-temperature flue gas recovery module and includes a high-temperature heat exchange unit and a low-temperature heat exchange unit arranged sequentially along the flue gas flow direction. It is used to perform two-stage heat exchange on the high-temperature flue gas to generate high-temperature hot water and low-temperature hot water respectively. The steam-hot water preparation module is connected to the cascade heat exchanger module and includes a steam generator, a high-temperature hot water storage tank, and a low-temperature hot water storage tank. The steam generator receives the high-temperature hot water as a heat source and converts pure water into steam. The high-temperature hot water storage tank and the low-temperature hot water storage tank are used to store the high-temperature hot water and low-temperature hot water prepared by the cascade heat exchanger module, respectively. The water supply module is connected to the high-temperature hot water storage tank, the low-temperature hot water storage tank, and the steam output end of the steam-hot water preparation module, respectively, and is used to distribute high-temperature hot water, low-temperature hot water, and steam to the corresponding water terminals. The intelligent control terminal is electrically connected to the high-temperature flue gas recovery module, the cascade heat exchanger module, the steam-hot water preparation module, and the water supply module, respectively, and is used to collect system operating parameters and automatically adjust the operating status of each module. The safety protection module is integrated into the critical pipelines and equipment of the system and is used to perform safety protection operations in case of over-temperature, over-pressure or abnormal operating conditions.

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