Multi-medium coupling high-efficiency thermal energy cascade utilization device and use method thereof

Abstract

The application discloses a kind of multi-medium coupling high-efficiency thermal energy cascade utilization device and its use method, device includes first heat exchanger and second heat exchanger, first heat exchanger includes first shell and internal first heat exchange tube, the first heat exchange tube includes concentrically arranged inner tube and outer tube, inner tube is supplied with waste heat water flow, outer tube is supplied with new water flow, through multi-medium coupling and the cascade utilization of residual heat of first heat exchanger and second heat exchanger in series, method is systematically integrated, and a closed loop heat energy flow network is constructed.The application is based on the efficient utilization of heat energy in cold-rolled degreasing production line, greatly improves the reutilization of waste heat resources, and saves the energy consumption of enterprise.

Description

Technical Field

[0001] This invention relates to the field of thermal energy utilization technology, and more specifically to a multi-medium coupled high-efficiency thermal energy cascade utilization device and its usage method. Background Technology

[0002] Currently, the existing manufacturing industry faces increasingly severe challenges in energy conservation and emission reduction, as well as the dual pressure of production cost control. For example, the waste gas and wastewater generated in the washing and degreasing processes of cold rolling degreasing lines have a lot of residual heat energy that can be recovered and utilized. If the drying waste gas and washing wastewater are directly discharged, not only will valuable fuel costs be wasted, but the high-temperature gas will also cause a heat island effect on the surrounding environment of the factory. If the high-temperature wastewater directly enters the sewage treatment system, it will increase the temperature control burden of the biochemical treatment process. Therefore, existing technologies often reuse waste gas and wastewater, such as using common gas-liquid heat exchangers or liquid-liquid heat exchangers to exchange heat energy, thereby heating room temperature water. The heated water is then used for washing, reducing the energy loss of heating water and solving the problem of high-temperature waste gas and wastewater discharge to a certain extent.

[0003] However, during use, it was found that there is still room for optimization in the above-mentioned existing technologies. For example, the flue gas temperature varies in different annealing processes. The flue gas temperature emitted from the first-stage annealing is very high, and it is difficult to fully utilize its heat energy in a single heat exchange. How to make full use of it is a problem that needs to be considered. Another example is that when using wastewater for heat exchange, suspended solids and grease in the wastewater are prone to deposit and blockage in long pipes, requiring frequent flushing and maintenance, which is quite troublesome. Furthermore, the existing heat exchanger structures are relatively simple, and they can only perform gas-liquid or liquid-liquid heat exchange. If it is necessary to utilize multiple waste heat media generated in the washing and degreasing processes of the cold rolling degreasing line and to reuse the residual heat media multiple times, a very long heat exchange production line needs to be built, which is not conducive to production layout and occupies a lot of production space. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multi-media coupling high-efficiency thermal energy cascade utilization device. Through a multi-media coupling technology route, it systematically integrates high-temperature rinsing wastewater from the degreasing line, low-temperature flue gas from the first-stage annealing furnace, and high-temperature flue gas from the third-stage annealing furnace to construct a closed-loop thermal energy circulation network.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-medium coupled high-efficiency thermal energy cascade utilization device, comprising a first heat exchanger and a second heat exchanger, the first heat exchanger comprising a first shell and an inner first heat exchange tube, the first heat exchange tube comprising an inner tube and an outer tube arranged concentrically, the inner tube being supplied with waste hot water and the outer tube being supplied with fresh water, and the first shell having an inlet A and an outlet A on both sides for supplying waste heat gas. The second heat exchanger includes a second shell and a second heat exchange tube and a third heat exchange tube inside. The second shell is provided with inlet B and outlet B and inlet C and outlet C in pairs on four sides for waste heat gas to flow through. Each of the inlet B, outlet B, inlet C and outlet C is provided with a valve plate for controlling opening and closing. The third heat exchange tube is positioned near inlet B, and the second heat exchange tube is positioned near inlet C; The second housing is provided with an air baffle plate, which is used to separate the air passages of inlet B and outlet B from the air passages of inlet C and outlet C. The inlet A is connected to the outlet B, the outlet of the outer pipe is connected to the inlet of the second heat exchange tube, and the outlet of the second heat exchange tube is connected to the inlet of the third heat exchange tube.

[0006] The present invention is further configured as follows: a cold rolling degreasing production line is included, wherein the degreasing rinsing wastewater in the production line is introduced into the inner tube; the first-stage annealing flue gas in the production line is introduced into inlet B; the third-stage annealing flue gas in the production line is introduced into inlet C; the outlet of the third heat exchange tube is connected to the hot water tank used for degreasing rinsing in the production line; outlets A and C are connected to the flue gas treatment device in the production line; the outlet of the inner tube is connected to the wastewater treatment device in the production line; and tap water is filtered by the filtration device in the production line to form the new water.

[0007] The present invention is further configured such that: the first heat exchange tube is configured as multiple sets of annular spiral pipes, each set of annular spiral pipes is provided with several U-shaped transition pipes, the inner pipe of the U-shaped transition pipe extends to the outside of the outer pipe, and a water pump is provided on the extended inner pipe; the two outer pipes of the U-shaped transition pipe are connected by a horizontal pipe.

[0008] The invention is further configured such that: the air-insulating plate is an arc-shaped plate that divides the second housing into chamber B and chamber C, and an isolation channel is provided in the middle of the air-insulating plate, the isolation channel connecting the outlet C and chamber C, and the upper and lower sides of the isolation channel connecting the outlet B and chamber B.

[0009] The present invention is further configured such that the inlets of the outer tube, the second heat exchange tube and the third heat exchange tube are all located at the bottom, and the outlets are all located at the top, so that the water inside flows from bottom to top in a counter-current manner.

[0010] The present invention is further configured such that: both the second heat exchange tube and the third heat exchange tube are configured as spirally coiled cylindrical structures, and both the second heat exchange tube and the third heat exchange tube are vertically arranged so that the airflow is directly facing the side of the cylindrical structure.

[0011] The present invention is further configured such that: the inlet and outlet of the second heat exchange tube and the third heat exchange tube are both located on the central axis of their corresponding cylindrical structures, and the inlet and outlet are connected to a rotary joint; the bottom of the second heat exchange tube and the third heat exchange tube are both provided with a rotating base; the rotating base drives the second heat exchange tube and the third heat exchange tube to rotate around the central axis of the cylindrical structure through a control system and a servo motor.

[0012] The invention is further configured such that: four temperature probes are provided at the four quadrant points of the second and third heat exchange tubes in the cylindrical structure, and at the positions centered at their inlet and outlet. The four temperature probes extend into the interior of the heat exchange tubes to detect the water temperature. The four temperature probes are electrically connected to the control system. The rotating chassis rotates in a reciprocating manner, and drives the temperature probe with the lowest detected temperature to rotate towards the temperature probe with the highest detected temperature.

[0013] The present invention is further configured such that: the valve plate includes a plurality of rotatable valve plates, and the opening and closing of the valve plate and the adjustment of the air passage direction are realized by the rotation of the valve plates.

[0014] The present invention further provides a method of using a multi-medium coupled high-efficiency thermal energy cascade utilization device, comprising the above-mentioned multi-medium coupled high-efficiency thermal energy cascade utilization device, including the following steps: Step 1: Introduce degreasing and rinsing wastewater, cooled first-stage annealing flue gas discharged from the first-stage annealing furnace, and fresh water formed after treatment of ambient temperature tap water into the first heat exchanger. Step 2: After the new water passes through the first heat exchanger, it forms preheated water and is discharged from the outlet of the outer pipe. It is then pumped into the second heat exchange tube of the second heat exchanger by the circulation pump. Step 3: The inlet C and outlet C of the second heat exchanger are continuously opened, so that the preheated water in the second heat exchange tube can exchange heat with the medium-temperature flue gas discharged from the third annealing process, raising the temperature of the preheated water to medium-temperature water, and the medium-temperature water is circulated into the third heat exchange tube through the circulation pump. Step 4: The inlet B and outlet B of the second heat exchanger are kept open, so that the medium-temperature water in the third heat exchange tube can exchange heat with the high-temperature flue gas emitted from the first-stage annealing process, raising the medium-temperature water to high-temperature water, and the high-temperature water is finally introduced into the hot water tank for degreasing and rinsing. Step 5: The first-stage annealing flue gas, after heat exchange in Step 4, still has residual heat. It is connected in series from outlet B to inlet A to form the cooled first-stage annealing flue gas in Step 1. Step 6: Repeat steps 1 to 5 to achieve tiered utilization of waste heat from the production line.

[0015] In summary, the present invention has the following beneficial effects: This invention utilizes a first heat exchanger and a second heat exchanger. The first heat exchanger enables simultaneous heat energy utilization of wastewater and waste gas, effectively preheating the fresh water. The second heat exchanger uses two flue gas gases at different temperatures for gradual, stepped heating, allowing the water temperature to rise steadily to a temperature suitable for hot water rinsing. Furthermore, the series connection of the first and second heat exchangers, along with the invention's structural design, significantly saves space and achieves highly efficient heat energy utilization.

[0016] In the first heat exchanger of the present invention, several U-shaped transition pipes and a water pump are provided on the first heat exchange tube. The water pump assists the flow of wastewater, avoiding the problem of wastewater flow rate decrease due to long-distance pipe flow, resulting in the deposition and blockage of suspended solids and grease, extending the maintenance cycle of the pipes, and making it more convenient to use. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the overall process of the device.

[0018] Figure 2 This is a simplified diagram of the internal structure of the second heat exchanger.

[0019] Figure 3 This is a schematic diagram of the first heat exchanger tube structure.

[0020] Figure 4 This is a schematic diagram of the cross-sectional structure of a U-shaped transition pipe.

[0021] Figure 5 This is a schematic diagram of the second or third heat exchanger tube structure.

[0022] Figure 6 This is a three-dimensional structural diagram of the air barrier.

[0023] Reference numerals: 01, First heat exchanger; 02, Second heat exchanger; 201, Chamber B; 202, Chamber C; 111. Inlet A; 112. Outlet A; 12. First heat exchange tube; 121. Inner tube; 122. Outer tube; 211. Air baffle; 2111. Isolation channel; 22. Second heat exchange tube; 221. Inlet B; 222. Outlet B; 223. Inlet C; 224. Outlet C; 23. Third heat exchange tube; 3. Valve plate; 4. U-shaped transition pipe; 41. Water pump; 5. Horizontal pipe; 7. Rotating chassis; 71. Servo motor; 72. Worm gear; 73. Worm wheel; 8. Temperature probe. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] This embodiment discloses a multi-medium coupled high-efficiency thermal energy cascade utilization device, such as... Figure 1-5 As shown, it includes a first heat exchanger 01 and a second heat exchanger 02. The first heat exchanger 01 includes a first shell and an internal first heat exchange tube 12. The first heat exchange tube 12 includes an inner tube 121 and an outer tube 122 arranged concentrically. The inner tube 121 is for waste hot water to flow through, and the outer tube 122 is for fresh water to flow through. The first shell has an inlet A111 and an outlet A112 on both sides for waste heat gas to flow through. With the above structure, the first heat exchanger 01 can simultaneously use the waste heat of waste water and waste heat gas to heat fresh water. Fresh water refers to tap water at room temperature after filtration. Waste hot water refers to waste water with a temperature of 50-55°C after degreasing and rinsing. Waste gas refers to flue gas emitted during annealing. Thus, the first heat exchanger 01 can perform preliminary heating of fresh water.

[0026] The second heat exchanger 02 includes a second shell and internal second heat exchange tubes 22 and third heat exchange tubes 23. The second shell has four corresponding inlet B221 and outlet B222, and inlet C223 and outlet C224 for waste heat gas flow. Each inlet B221, outlet B222, inlet C223, and outlet C224 is equipped with a valve plate 3 for controlling opening and closing. The third heat exchange tube 23 is positioned close to inlet B221, and the second heat exchange tube 22 is positioned close to inlet C223. An air baffle 221 is installed inside the second shell to separate the gas passages of inlet B221 and outlet B222 from those of inlet C223 and outlet C224. Through this structure, the second heat exchanger 02 achieves efficient heat exchange through a reasonable internal layout. The design allows waste heat gas flowing through inlet C223 and outlet C224 to heat the water in the second heat exchange tube 22, while waste heat gas flowing through inlet B221 and outlet B222 can heat the water in the third heat exchange tube 23. The second heat exchanger 02 utilizes both types of waste heat gas simultaneously. Traditional heat exchangers, however, can only exchange heat from one type of waste gas at a time. Utilizing both types requires two heat exchangers, resulting in a larger volume, longer pipelines, and wasted waste heat. The second heat exchanger 02 of this invention not only saves one heat exchanger, reducing the overall volume and shortening the waste heat pipeline, but also increases the overall internal temperature of the second heat exchanger 02 by utilizing both types of waste heat gas, making heat dissipation less likely and improving waste heat utilization efficiency. To further insulate, both the first and second shells are covered with insulation material to reduce heat loss due to outward dissipation.

[0027] Meanwhile, inlet A111 is connected to outlet B222, and the outlet of outer pipe 122 is connected to the inlet of second heat exchange tube 22; the outlet of second heat exchange tube 22 is connected to the inlet of third heat exchange tube 23. Through the above connection method, the first heat exchanger 01 and the second heat exchanger 02 form an integrated device for the cascade utilization of thermal energy. Fresh water is first preheated by passing through the first heat exchanger 01, then further heated by passing through the second heat exchange tube 22 of the second heat exchanger 02, and finally heated to the final temperature by passing through the third heat exchange tube 23. During this process, the waste heat of the waste gas from the final heating of the second heat exchanger can be reused through inlet A111, achieving the effect of cascade utilization.

[0028] As a further preferred embodiment, the present invention is well adapted to a cold rolling degreasing production line. The degreasing and rinsing wastewater in the production line is introduced into the inner pipe 121; the first-stage annealing flue gas in the production line is introduced into inlet B221; the third-stage annealing flue gas in the production line is introduced into inlet C223; the outlet of the third heat exchanger 23 is connected to the hot water tank used for degreasing and rinsing in the production line; outlets A111 and C224 are connected to the flue gas treatment device in the production line; the outlet of the inner pipe 121 is connected to the wastewater treatment device in the production line; tap water is filtered by the filtration device in the production line to form the aforementioned fresh water. Thus, the device of the present invention fully utilizes the waste heat of the annealing flue gas and rinsing wastewater in the cold rolling degreasing production line. In particular, the first-stage annealing flue gas in the production line has a very high exhaust heat of approximately 160°C. After final heating, it still retains preheat, which is then reused in the first heat exchanger 01 for secondary utilization, achieving full utilization of the production line's thermal energy.

[0029] Further, as a preferred option, refer to Figure 3-4The first heat exchange tube 12 is configured as multiple sets of annular spiral pipes. Each set of annular spiral pipes is provided with several U-shaped transition pipes 4. The inner pipe 121 of the U-shaped transition pipe 4 extends to the outside of the outer pipe 122, and a water pump 41 is provided on the extended inner pipe 121. The two outer pipes 122 on both sides of the U-shaped transition pipe 4 are connected by a horizontal pipe 5. Specifically, wastewater returns through the U-shaped transition pipe 4 and the water pump 41, while fresh water returns directly through the horizontal pipe 5. The reason for this design is that the wastewater generated during the rinsing process contains a large amount of alkaline substances and oil, which are easily scaled suspended solids and corrosive. After sampling and testing, the pH value of the wastewater is stable at 10.66-10.76, and the main components are residual sodium hydroxide (NaOH) and sodium carbonate (Na2CO3), which places stringent requirements on the corrosion resistance of the heat exchanger material. At the same time, the wastewater also has a high organic load: COD is as high as 326.6-419.9 mg / L, mainly from emulsified rolling oil, lubricating oil, and surfactants in degreasing agents. These organic substances are easily precipitated during the cooling process and adhere to the pipe wall; the suspended solids contain trace amounts of iron powder (Fe) and iron oxide scale. When the wastewater flows through the heat exchange surface, the oily organic matter and iron powder particles easily form a sticky composite fouling (a mixture of soft and hard fouling) under alkaline conditions. This fouling has an extremely low thermal conductivity, which will rapidly reduce the efficiency of ordinary heat exchangers and even cause flow channel blockage. Therefore, the inner tube 121 is made of high-grade corrosion-resistant stainless steel, which can withstand strong alkali erosion for a long time. Through the setting of U-shaped transition pipe 4 and water pump 41, the wastewater is driven by the water pump to gain power multiple times in the pipe, which increases the flow rate and disturbs the water turbulence, preventing the deposition of grease and suspended solids, realizing online self-cleaning, and the wastewater is not easy to scale and clog. The turbulence of the wastewater also increases the contact between the water and the pipe wall, better releasing the internal residual heat temperature, resulting in better heat exchange effect. It is best to set one U-shaped transition pipe every 6m-8m to continuously provide turbulent power for the wastewater.

[0030] Further reference Figure 2 and Figure 6The baffle plate 211 is configured as an arc-shaped plate that divides the second shell into chambers B201 and C202. The arc shape helps to better guide the gas flow. An isolation channel 2111 is provided in the middle of the baffle plate 211. The isolation channel 2111 itself connects the outlet C224 and the chamber C202, so that the exhaust gas entering from the outlet C224 flows in the airflow direction b shown in the figure. The upper and lower sides of the isolation channel 2111 connect the outlet B222 and the chamber B201, so that the gas entering from the inlet B221 flows in the airflow direction a shown in the figure. Through the above structure, the second heat exchanger 02 is provided with two mutually separated air passages, allowing exhaust gases of different temperatures to exchange heat in one heat exchanger, reducing the overall equipment volume and saving space. Furthermore, the two exhaust gases entering the same heat exchanger allow the temperature of the exhaust gases inside the equipment to be utilized, increasing the overall internal temperature of the equipment and reducing heat dissipation and waste.

[0031] Further reference Figure 3 and Figure 5 The inlets of the outer tube 122, the second heat exchange tube 22, and the third heat exchange tube 23 are all located at the bottom, and the outlets are all located at the top, allowing the water inside to flow counter-currently from bottom to top. This method ensures that fresh water fills the entire tube, guaranteeing sufficient heat exchange. Furthermore, wastewater in the inner tube 121 can be selected to enter from the top and exit from the bottom, which increases the flow rate and power of the wastewater and also helps prevent scale buildup.

[0032] Further reference Figure 2 and Figure 5 Since the second and third heat exchange tubes have the same structure, Figure 5 Only one structure is shown for ease of illustration. Both the second heat exchange tube 22 and the third heat exchange tube 23 are spirally coiled cylindrical structures, and both are vertically arranged so that the airflow faces the side of the cylindrical structure. This structural arrangement maximizes the contact area between the exhaust gas and the tube body within the limited space of the second heat exchanger. Furthermore, the inlet and outlet of both the second and third heat exchange tubes 22 and 23 are located on the central axis of their respective cylindrical structures, and are connected to rotary joints. A rotating base 7 is provided at the bottom of both the second and third heat exchange tubes 22 and 23. The rotating base 7, driven by a control system and a servo motor, rotates the second and third heat exchange tubes 22 and 23 around the central axis of their cylindrical structures. With this structure, the second heat exchange tube 22 and the third heat exchange tube 23 can rotate, thereby making more comprehensive contact with the waste heat gas and improving heat exchange efficiency; and it will not interfere with the connection between the inlet and outlet and the external pipeline; the specific structure of the rotating chassis can be found in [reference needed]. Figure 5The rotating chassis is supported on a rotatable bearing, and then the worm gear 72 is driven to rotate by the servo motor 71. The worm gear 72 then drives the worm wheel 73 to rotate, and the worm wheel transmits the power to the rotating chassis 7, thereby driving the heat exchange tubes on it to rotate slowly.

[0033] Further optimization, in order to better improve the utilization of waste heat, four temperature probes 8 are installed at the four quadrant points of the cylindrical second heat exchange tube 22 and the third heat exchange tube 23, and at the positions of their inlet and outlet. The four temperature probes 8 extend into the interior of the heat exchange tube to detect the water temperature. The four temperature probes 8 are electrically connected to the control system. Since the second and third heat exchange tubes are sideways to the air intake direction, there will be a temperature difference between the different sides. Theoretically, the temperature is highest when facing the air intake direction and lowest when facing away from the air intake direction. Therefore, the rotating chassis 7 can rotate in a reciprocating manner, and drive the temperature probe with the lowest detected temperature to rotate towards the temperature probe with the highest detected temperature. This avoids the connection wires of temperature probe 8 getting tangled. Secondly, the rotation speed and frequency are controlled intelligently. By setting a threshold, when the temperature on the opposite side reaches the threshold (set by the staff based on experience), it means that the opposite side has reached the saturation level of heat absorption. At this time, the rotation is controlled to make the side with lower temperature face the air intake direction, achieving a better heat exchange effect. Moreover, compared with continuous rotation, this intermittent rotation saves more energy.

[0034] Further, as a preferred embodiment, refer to Figure 2 The valve plate 3 includes several rotatable valve pieces. The opening and closing of the valve plate 3 and the adjustment of the air passage direction are realized by the rotation of the valve pieces. The valve pieces can be driven by the cylinder connecting rod or motor gear, so that the exhaust gas at different positions flows towards the heat exchange tube, which is also used to improve the heat exchange effect.

[0035] The present invention further provides a method of using a multi-medium coupled high-efficiency thermal energy cascade utilization device, comprising using the above-mentioned multi-medium coupled high-efficiency thermal energy cascade utilization device in a cold rolling degreasing production line, and further comprising the following steps: Step 1: Degreasing and rinsing wastewater, cooled flue gas from the first-stage annealing furnace, and fresh water formed after treatment of ambient temperature tap water are introduced into the first heat exchanger. Step 1 is used to generate preheated water. The degreasing and rinsing wastewater is approximately 50-55 degrees Celsius, and it is combined with flue gas. In this step, the sensible heat of the wastewater is used for initial heating, while the low-temperature flue gas provides supplementary heating. The temperature of the fresh water is effectively raised to 40-50 degrees Celsius, becoming preheated water. This step not only recovers heat but also significantly reduces the discharge temperature of the wastewater, alleviating the heat load on the subsequent wastewater treatment plant.

[0036] Step 2: After the new water passes through the first heat exchanger, it forms preheated water and is discharged from the outlet of the outer pipe. It is then pumped into the second heat exchange tube of the second heat exchanger by the circulation pump. Step 3: The inlet C and outlet C of the second heat exchanger remain open, allowing the preheated water in the second heat exchange tube to exchange heat with the medium-temperature flue gas emitted from the third-stage annealing process, raising the temperature of the preheated water to medium-temperature water. The medium-temperature water is then pumped into the third heat exchange tube via a circulation pump. Steps 2 and 3 are used to generate medium-temperature water. The temperature of the medium-temperature flue gas emitted from the third-stage annealing process is approximately 120-130 degrees Celsius. After heat exchange, the water temperature can be raised to 60-65 degrees Celsius, thus becoming medium-temperature water.

[0037] Step 4: The inlet B and outlet B of the second heat exchanger remain open, allowing the medium-temperature water in the third heat exchange tube to exchange heat with the high-temperature flue gas emitted from the first-stage annealing process, raising the temperature of the medium-temperature water to high-temperature water. The high-temperature water is then introduced into the hot water tank used for degreasing rinsing. Step 4 is used to generate high-temperature water that can be used in the degreasing line rinsing tank. The high-temperature flue gas emitted from the first-stage annealing process is about 160 degrees Celsius. After the medium-temperature water enters, the temperature is rapidly raised through heat exchange, eventually reaching the target value of 80 degrees Celsius, which can be used in the degreasing line rinsing tank.

[0038] Step 5: The first-stage annealing flue gas, after heat exchange in Step 4, still has residual heat. It is connected in series from outlet B to inlet A to form the cooled first-stage annealing flue gas in Step 1. In Step 5, the high-temperature flue gas is reused. Although the temperature of the first-stage annealing flue gas is reduced after heat exchange, it still has residual heat. It is connected in series to the first-stage heat exchanger to make full use of the residual heat of the flue gas.

[0039] Step 6: Repeat steps 1 to 5 to achieve tiered utilization of waste heat from the production line.

[0040] Through the aforementioned device and method, the first heat exchanger achieves heat exchange between wastewater, fresh water, and flue gas within different annular channels of the same equipment, realizing highly efficient coupled heat exchange of multiple media. Compared to traditional single-media heat exchangers, it boasts higher thermal efficiency and a smaller footprint. Simultaneously, the second heat exchanger comprehensively utilizes both types of flue gas, similarly reducing the footprint and resulting in a very compact overall device, making it particularly suitable for upgrading and retrofitting degreasing production lines. Furthermore, this invention strictly adheres to the second law of thermodynamics, designing a precise series heat exchange process based on the principles of "temperature matching, tiered utilization, and energy level matching," fully utilizing waste heat resources of different grades and forms.

[0041] This embodiment has been experimentally verified to have the capability to continuously heat approximately 10 t / h of ambient temperature cold water to a temperature of 80 degrees Celsius or higher around the clock, fully meeting the full-load operation requirements of the production line. Through multi-stage waste heat recovery, the steam consumption of the entire system is reduced by 50%, specifically addressing the heat exchange problem of highly fouled wastewater, ensuring a long online operating cycle for the heat exchanger, low maintenance frequency, and eliminating the risk of production stoppage due to heat exchanger blockage.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the design concept of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-medium coupled high-efficiency thermal energy cascade utilization device, characterized in that: It includes a first heat exchanger (01) and a second heat exchanger (02). The first heat exchanger (01) includes a first shell and an inner first heat exchange tube (12). The first heat exchange tube (12) includes an inner tube (121) and an outer tube (122) arranged concentrically. The inner tube (121) is used for waste hot water circulation, and the outer tube (122) is used for fresh water circulation. The first shell is provided with an inlet A (111) and an outlet A (112) for waste heat gas circulation on both sides. The second heat exchanger (02) includes a second shell and a second heat exchange tube (22) and a third heat exchange tube (23) inside. The second shell is provided with inlet B (221), outlet B (222) and inlet C (223) and outlet C (224) in pairs on four sides for waste heat gas to flow. Each of the inlet B (221), outlet B (222), inlet C (223) and outlet C (224) is provided with a valve plate (3) for controlling opening and closing. The third heat exchange tube (23) is positioned near inlet B (221), and the second heat exchange tube (22) is positioned near inlet C (223); The second housing is provided with an air baffle (211), which is used to separate the air passages of inlet B (221) and outlet B (222) from the air passages of inlet C (223) and outlet C (224); The inlet A (111) is connected to the outlet B (222), the outlet of the outer tube (122) is connected to the inlet of the second heat exchange tube (22), and the outlet of the second heat exchange tube (22) is connected to the inlet of the third heat exchange tube (23).

2. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 1, characterized in that: The system includes a cold rolling degreasing production line, in which degreasing and rinsing wastewater is fed into the inner pipe (121); the first-stage annealing flue gas in the production line is fed into inlet B (221); the third-stage annealing flue gas in the production line is fed into inlet C (223); the outlet of the third heat exchange tube (23) is connected to the hot water tank used for degreasing and rinsing in the production line; outlet A (111) and outlet C (224) are connected to the flue gas treatment device in the production line. The outlet of the inner pipe (121) is connected to the wastewater treatment device in the production line; the tap water is filtered by the filtration device in the production line to form the new water.

3. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 1, characterized in that: The first heat exchange tube (12) is configured as multiple sets of annular spiral pipes, and each set of annular spiral pipes is provided with several U-shaped transition pipes (4). The inner tube (121) of the U-shaped transition pipe (4) extends to the outside of the outer tube (122), and a water pump (41) is provided on the extended inner tube (121). The two outer tubes (122) in the U-shaped transition pipe (4) are connected by a horizontal pipe (5).

4. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 1, characterized in that: The air baffle (211) is configured as an arc-shaped plate that divides the second housing into chamber B (201) and chamber C (202), and an isolation channel (2111) is provided in the middle of the air baffle (211). The isolation channel (2111) connects the outlet C (224) and the chamber C (202), and the upper and lower sides of the isolation channel (2111) connect the outlet B (222) and the chamber B (201).

5. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 1, characterized in that: The inlets of the outer tube (122), the second heat exchange tube (22), and the third heat exchange tube (23) are all located at the bottom, and the outlets are all located at the top, so that the water inside flows from bottom to top in a counter-current manner.

6. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 1, characterized in that: The second heat exchange tube (22) and the third heat exchange tube (23) are both configured as a spirally coiled cylindrical structure, and the second heat exchange tube (22) and the third heat exchange tube (23) are both vertically arranged so that the airflow is directly facing the side of the cylindrical structure.

7. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 6, characterized in that: The inlet and outlet of the second heat exchange tube (22) and the third heat exchange tube (23) are both located on the central axis of their corresponding cylindrical structures, and the inlet and outlet are connected to a rotary joint. The bottom of the second heat exchange tube (22) and the third heat exchange tube (23) are both provided with a rotating base (7). The rotating base (7) drives the second heat exchange tube (22) and the third heat exchange tube (23) to rotate around the central axis of the cylindrical structure through the control system and the servo motor.

8. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 7, characterized in that: Four temperature probes (8) are installed at the four quadrant points of the second heat exchange tube (22) and the third heat exchange tube (23) in a cylindrical structure, and at the positions of their inlet and outlet. The four temperature probes (8) extend into the interior of the heat exchange tube to detect the water temperature. The four temperature probes (8) are electrically connected to the control system. The rotating chassis (7) rotates in a reciprocating manner, and drives the temperature probe with the lowest detected temperature to rotate towards the temperature probe with the highest detected temperature.

9. The multi-medium coupled high-efficiency thermal energy cascade utilization device according to claim 1, characterized in that: The valve plate (3) includes several rotatable valve pieces, and the opening and closing of the valve plate (3) and the adjustment of the air passage direction are realized by the rotation of the valve pieces.

10. A method of using a multi-medium coupled high-efficiency thermal energy cascade utilization device, comprising the multi-medium coupled high-efficiency thermal energy cascade utilization device as described in claim 2, characterized in that: Includes the following steps: Step 1: Introduce degreasing and rinsing wastewater, cooled first-stage annealing flue gas discharged from the first-stage annealing furnace, and fresh water formed after treatment of ambient temperature tap water into the first heat exchanger. Step 2: After the new water passes through the first heat exchanger, it forms preheated water and is discharged from the outlet of the outer pipe. It is then pumped into the second heat exchange tube of the second heat exchanger by the circulation pump. Step 3: The inlet C and outlet C of the second heat exchanger are continuously opened, so that the preheated water in the second heat exchange tube can exchange heat with the medium-temperature flue gas discharged from the third annealing process, raising the temperature of the preheated water to medium-temperature water, and the medium-temperature water is circulated into the third heat exchange tube through the circulation pump. Step 4: The inlet B and outlet B of the second heat exchanger are kept open, so that the medium-temperature water in the third heat exchange tube can exchange heat with the high-temperature flue gas emitted from the first-stage annealing process, raising the medium-temperature water to high-temperature water, and the high-temperature water is finally introduced into the hot water tank for degreasing and rinsing. Step 5: The first-stage annealing flue gas, after heat exchange in Step 4, still has residual heat. It is connected in series from outlet B to inlet A to form the cooled first-stage annealing flue gas in Step 1. Step 6: Repeat steps 1 to 5 to achieve tiered utilization of waste heat from the production line.

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