Intelligent heat exchange unit for sewage waste heat recovery

Abstract

The invention discloses an intelligent heat exchange unit for sewage waste heat recovery, which comprises a sewage system, a clear water system and an intelligent control system, and is characterized in that the sewage system is internally provided with at least two sets of filtering devices capable of switching between a filtering state and a backwashing state; the intelligent control system is configured to automatically control the sewage system to switch the water flow direction, so that the filtering device in the filtering state is switched to a backwashing state; after the water flow direction is switched, the health state of the backwashed filtering device continues to be monitored, and if the backwashed filtering device does not recover to a preset health state within a preset first time period, an online dosing cleaning program is automatically started. According to the invention, when the heat exchange unit is in a running state, the heat exchange unit can filter entering sewage in real time, automatically identify mild scaling or blockage and execute a non-stop automatic backwashing instruction, so that the scaling possibility of a pipeline and equipment can be reduced, blockage is avoided, and the heat exchange unit is ensured to stably and reliably run for a long time.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery, and specifically to a smart heat exchanger unit for waste heat recovery from sewage. Background Technology

[0002] The production processes in industries such as dyeing, slaughtering, and food processing generate large amounts of high-temperature wastewater containing significant heat energy. Recovering and utilizing this waste heat can not only reduce energy consumption for businesses but also decrease thermal pollution to the environment, aligning with current trends in energy conservation and emission reduction. With industrial development, wastewater heat recovery is receiving increasing attention, as it plays a crucial role in improving energy efficiency and promoting sustainable development.

[0003] In the field of wastewater waste heat recovery, conventional methods for solving the problem include directly using conventional heat exchangers to recover wastewater heat. However, due to the high levels of impurities in wastewater, pretreatment is necessary to ensure the normal operation of the heat exchangers, such as filtration to remove some impurities. Additionally, some companies regularly maintain and clean their heat exchangers to reduce scaling and clogging. While these methods can achieve wastewater waste heat recovery to some extent, they have many limitations in practical applications.

[0004] In existing technologies, directly using conventional heat exchangers to recover waste heat from wastewater leads to a series of problems. Because wastewater contains many impurities, conventional heat exchangers are prone to scaling and frequent clogging during operation, and are also difficult to maintain. These problems result in low utilization rates of waste heat, significantly hindering the widespread application of wastewater waste heat recovery technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a smart heat exchanger unit for wastewater waste heat recovery.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention provides a smart heat exchanger unit for wastewater waste heat recovery, comprising a wastewater system for guiding wastewater flow, a clean water system for guiding clean water flow and exchanging heat with the wastewater, and a smart control system. The wastewater system includes at least two sets of filtration devices that can switch between filtration and backwashing states. The smart control system is configured to: (a) Real-time monitoring of the first pressure difference before and after the filter device currently in the filtration state; (b) When the first pressure difference reaches a preset first threshold, the sewage system is automatically controlled to switch the water flow direction, so that the filter device in the filtration state switches to the backwash state. (c) After switching the water flow direction, continue to monitor the health status of the backwashed filter device. If it fails to recover to a preset health status within the preset first time period, the online dosing cleaning program will be automatically started. Cleaning agent will be injected into the sewage system while the smart heat exchanger unit for waste heat recovery is continuously recovering waste heat.

[0007] In some embodiments, the wastewater system includes: Wastewater buffer tank, which is equipped with a wastewater outlet; The sewage pump has its inlet connected to the sewage outlet of the sewage buffer tank via a sewage inlet valve. The sewage flow direction switching valve group consists of a sewage reversing first valve, a sewage reversing second valve, a sewage reversing third valve, and a sewage reversing fourth valve connected clockwise by a pipeline. The outlet of the sewage pump is connected to the pipeline between the sewage reversing first valve and the sewage reversing second valve. Heat exchange device; The first filtration device has one end connected to the pipeline between the first sewage reversing valve and the fourth sewage reversing valve, and the other end connected to the first sewage side interface of the heat exchange device. The second filtration device has one end connected to the second sewage side interface of the heat exchange device, and the other end connected to the pipeline between the sewage reversing second valve and the sewage reversing third valve. A sewage discharge tank is connected to the pipeline between the third sewage reversing valve and the fourth sewage reversing valve.

[0008] In some embodiments, both the first filter device and the second filter device have detachable glass viewing windows on their sidewalls.

[0009] In some embodiments, the water purification system includes: Clear water buffer tank; A clean water pump, the inlet of which is connected to the outlet of the clean water buffer tank; A clean water flow direction switching valve group, which consists of a first clean water switching valve, a second clean water switching valve, a third clean water switching valve, and a fourth clean water switching valve connected counterclockwise through a pipeline, and the outlet of the clean water pump is connected to the pipeline between the first clean water switching valve and the second clean water switching valve. A hot water storage tank, wherein the hot water storage tank is connected to the pipeline between the third water diversion valve and the fourth water diversion valve; The first clean water side interface of the heat exchange device is connected to the pipeline between the second clean water reversing valve and the third clean water reversing valve; The second clean water side interface of the heat exchange device is connected to the pipeline between the first clean water reversing valve and the fourth clean water reversing valve.

[0010] In some embodiments, the intelligent heat exchanger unit for wastewater waste heat recovery further includes an automatic dosing system, which includes: The solution tank includes a tank body, an automatic stirrer and a clean water inlet located on the top of the tank body, a solution outlet and a drain outlet located at the bottom of the tank body, and a dosing tank with a steel filter structure located inside the tank body. A dosing system inlet valve is connected between the outlet of the clean water pump and the clean water inlet of the solution tank; The dosing system outlet valve has its inlet connected to the solution outlet of the solution tank, and its outlet connected to the inlet of the first dosing pipeline valve. The first dosing pipeline valve, the outlet of the first dosing pipeline valve is connected to the pipeline between the sewage inlet valve and the sewage pump; The second dosing line valve has its inlet connected to the pipeline between the dosing system outlet valve and the first dosing line valve, and its outlet connected to the pipeline between the second filter device and the sewage flow direction switching valve group.

[0011] In some embodiments, the intelligent control system includes a sensing component, the sensing component comprising: A first pressure transmitter is installed between the sewage flow direction switching valve group and the first filter device; A second pressure transmitter and a first temperature sensor on the wastewater side are installed between the first filtration device and the heat exchange device. A third pressure transmitter and a second temperature sensor on the wastewater side are installed between the heat exchange device and the second filter device. A fourth pressure transmitter is installed between the second filtration device and the sewage flow direction switching valve group; A wastewater flow meter is installed at the inlet end of the wastewater discharge tank; A clean water flow meter installed at the inlet of the hot water storage tank; A sewage buffer tank level sensor is installed on the sewage buffer tank; A water level sensor is installed on the water buffer tank. A hot water storage tank level sensor is installed on the hot water storage tank; And a solution tank level sensor installed on the solution tank.

[0012] In some embodiments, the first threshold is 1.3-1.8 times the pressure difference of the filter device in its initial clean state.

[0013] In some embodiments, the first threshold is 1.5 times the pressure difference of the filter device in its initial clean state.

[0014] In some embodiments, the health status is defined as a pressure difference across the filter device that is less than 1.05-1.15 times its pressure difference in the initial clean state.

[0015] In some embodiments, the first time period is 0.1-0.5 hours.

[0016] Compared with existing technologies, the beneficial effects of the intelligent heat exchanger unit for wastewater waste heat recovery provided by this invention include: (1) When the heat exchange unit is in operation, it can filter the incoming sewage in real time and automatically identify slight scaling or blockage, and execute the automatic backwash command without stopping the machine. This can reduce the possibility of scaling in the pipes and equipment, avoid blockage, and thus ensure the long-term stable and reliable operation of the heat exchange unit. (2) When the system determines that there is severe scaling or blockage, it will automatically start the online intelligent cleaning mode. In addition, when the equipment is shut down for standby, the operator can start the offline intelligent cleaning mode with one click, which solves the problem of difficult maintenance of traditional heat exchange units. (3) Since automatic backwashing or online intelligent cleaning mode can be carried out without interrupting waste heat recovery, the unit realizes dynamic protection of the heat exchange unit, thereby improving the utilization rate of the equipment while recovering waste heat from sewage in a high-efficiency manner. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a smart heat exchanger unit for wastewater waste heat recovery provided in an embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the sewage system in the image; Figure 3 yes Figure 1 A schematic diagram of the water purification system in the diagram; Figure 4 yes Figure 1 A schematic diagram of the automatic dosing system in the image; Figure 5 yes Figure 4 A schematic diagram of the solution tank in the diagram; Explanation of reference numerals in the attached drawings: 1-Wastewater system, 11-Wastewater buffer tank, 111-Wastewater outlet, 112-Overflow port, 12-Wastewater inlet valve, 13-Wastewater pump, 14-Wastewater flow direction switching valve assembly, 141-Wastewater reversing valve 1, 142-Wastewater reversing valve 2, 143-Wastewater reversing valve 3, 144-Wastewater reversing valve 4, 15-Heat exchange device, 151-First wastewater side interface, 152-Second wastewater side interface, 153-First clean water... 154-Second clean water side interface, 16-First filter device, 17-Second filter device, 18-Sewage discharge tank, 2-Clear water system, 21-Clear water buffer tank, 22-Clear water pump, 23-Clear water flow direction switching valve group, 231-Clear water reversing valve 1, 232-Clear water reversing valve 2, 233-Clear water reversing valve 3, 234-Clear water reversing valve 4, 24-Hot water storage tank, 3-Automatic dosing system, 31-Solution tank, 31 0-Tank body, 311-Automatic stirrer, 312-Clean water inlet, 313-Solution outlet, 314-Drain port, 315-Manual valve, 316-Check valve, 317-Overflow pipe, 318-Dosing tank, 319-Sealing cover, 32-Dosing system inlet valve, 33-Dosing system outlet valve, 34-First dosing pipeline valve, 35-Second dosing pipeline valve, 4-Intelligent control system, 41-First pressure transmitter, 42-Second pressure transmitter 43-Third pressure transmitter, 44-Fourth pressure transmitter, 45-First temperature sensor on the wastewater side, 46-Second temperature sensor on the wastewater side, 47-First temperature sensor on the clean water side, 48-Second temperature sensor on the clean water side, 49-Wastewater flow meter, 410-Clean water flow meter, 411-Wastewater buffer tank level sensor, 412-Clean water buffer tank level sensor, 413-Hot water storage tank level sensor, 414-Solution tank level sensor. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of the present invention, but are not limited thereto. Other embodiments obtained by those skilled in the art in conjunction with the embodiments of the present invention without creative effort are also within the protection scope of the present invention.

[0019] Please refer to Figure 1-Figure 4 This application mainly adopts a wastewater system 1, a clean water system 2 and a smart control system 4 to coordinate heat exchange and recover waste heat, which achieves efficient recovery of wastewater waste heat and solves the problem of easy scaling and clogging. The following is a further detailed description of this application.

[0020] The intelligent heat exchanger unit for wastewater waste heat recovery provided in this application includes a wastewater system 1 for guiding wastewater flow, a clean water system 2 for guiding clean water flow and exchanging heat with wastewater, an automatic dosing system 3, and an intelligent control system 4. At least two sets of filtration devices within the wastewater system 1 can switch between filtration and backwashing states. The intelligent control system 4 can monitor the status of the filtration devices in real time and automatically control the flow direction of the wastewater system 1 and initiate online dosing and cleaning procedures based on pressure differences and health status. This ensures the long-term stable operation of the heat exchanger unit and achieves efficient wastewater waste heat recovery. This is because the switching and cleaning of the filtration devices effectively reduces the impact of impurities on heat exchange and maintains system smooth operation.

[0021] For details, please refer to Figure 1 and Figure 2 The sewage system 1 includes a sewage buffer tank 11, a sewage pump 13, a sewage flow direction switching valve group 14, a heat exchange device 15, a first filter device 16, a second filter device 17, and a sewage discharge pool 18.

[0022] The wastewater buffer tank 11 is equipped with a wastewater outlet 111 and an overflow port 112. It is typically made of corrosion-resistant metal materials, such as stainless steel, and is generally cylindrical in shape to effectively store wastewater. In some special cases, a plastic tank can also be used, as long as it meets the requirements for corrosion resistance and wastewater storage. The wastewater pump 13 is a variable frequency pump, and its inlet is connected to the wastewater outlet of the wastewater buffer tank 11 via a wastewater inlet valve 12. The variable frequency pump can adjust its power according to the actual wastewater flow rate demand to achieve energy saving. The wastewater pump 13 is generally a centrifugal pump, which features high flow rate and high head. Of course, other types of pumps, such as screw pumps, can also be used, as long as they can transport wastewater.

[0023] The sewage flow direction switching valve assembly 14 consists of a first sewage switching valve 141, a second sewage switching valve 142, a third sewage switching valve 143, and a fourth sewage switching valve 144 connected clockwise via pipelines. The outlet of the sewage pump 13 is connected to the pipeline between the first sewage switching valve 141 and the second sewage switching valve 142. These automatic valves are typically electric or pneumatic ball valves, which have the advantages of fast opening and closing speed and good sealing performance. Other types of valves, such as electric or pneumatic butterfly valves, can also be used, as long as they can achieve the switching of water flow direction.

[0024] The heat exchanger 15 is a key component for heat exchange between wastewater and clean water. To reduce the risk of corrosion or clogging, a wide-channel spiral plate heat exchanger or plate heat exchanger made of corrosion-resistant material can be used. These heat exchangers have the advantages of high heat exchange efficiency and small footprint, and their wide-channel design is particularly suitable for wastewater conditions with high impurity levels. To ensure optimal heat exchange performance, the cold and hot media in the heat exchanger 15 maintain a highly efficient counter-current heat transfer state. One end of the first filter 16 is connected to the pipeline between the first wastewater reversing valve 141 and the fourth wastewater reversing valve 144, and the other end is connected to the first wastewater side interface 151 of the heat exchanger 15. The first filter 16 typically uses a screen filter, which can be made of stainless steel and effectively filters impurities in the wastewater. Other types of filters, such as activated carbon filters, can also be used, as long as they can filter the wastewater. One end of the second filter 17 is connected to the second wastewater side interface 152 of the heat exchanger 15, and the other end is connected to the pipeline between the second wastewater reversing valve 142 and the third wastewater reversing valve 143. Its structure is similar to that of the first filter device 16, and it also serves the functions of filtration and backwashing. The sewage discharge tank 18 is used to collect treated sewage and is generally made of concrete, which is sturdy and durable.

[0025] The combined logic of wastewater system 1 is as follows: wastewater first enters the wastewater buffer tank 11, and then is pumped by the wastewater pump 13 to the wastewater flow switching valve group 14. Depending on the state of the switching valve group 14, the wastewater flows through the corresponding filtration device and heat exchange device 15, and finally enters the wastewater discharge tank 18. This combination can achieve wastewater filtration, heat exchange and discharge, and the backwashing function is achieved through the switching of the filtration device to ensure the cleanliness of the system.

[0026] The working process of the sewage system is as follows: The function of wastewater system 1 is to transport wastewater and exchange heat with clean water system 2. Simultaneously, through a clever flow path design, it achieves online dynamic backwashing to maintain system cleanliness. Its operation mainly consists of two modes: forward operation and reverse operation.

[0027] Forward Operation (First Filter Device 16 Filters, Second Filter Device 17 Backwashes): When the operator starts the heat exchange mode, the intelligent control system 4 automatically opens the sewage inlet valve 12, the sewage reversing first valve 141, and the sewage reversing third valve 143 after confirming that the liquid levels in each tank are normal. The sewage pump 13 starts, drawing sewage from the sewage buffer tank 11, which then flows sequentially through the sewage inlet valve 12, the sewage pump 13, the sewage reversing first valve 141, and the first filter device 16. In the first filter device 16, suspended solids and impurities in the sewage are effectively intercepted. The filtered clean sewage enters the heat exchange device 15, releases heat, and then flows through the second filter device 17. At this time, the clean sewage washes away the impurities deposited in the second filter device 17 from the reverse direction, completing the online backwashing of the second filter device 17. Finally, the sewage carrying impurities is discharged into the sewage discharge pool 18 through the sewage reversing third valve 143 and the sewage flow meter 49.

[0028] Reverse Operation (Second Filter Device 17 Filters, First Filter Device 16 Backwashes): During forward operation, the intelligent control system 4 monitors the pressure difference before and after the first filter device 16 in real time via the first pressure transmitter 41 and the second pressure transmitter 42. When this pressure difference reaches a preset threshold (e.g., 1.5 times that in the clean state), it indicates that the first filter device 16 has become clogged. The system will automatically switch to reverse operation mode. During the switch, the system closes the first sewage reversing valve 141 and the third sewage reversing valve 143, and opens the second sewage reversing valve 142 and the fourth sewage reversing valve 144. At this time, the sewage flow path becomes: sewage pump 13 -> sewage reversing valve 142 -> second filter device 17 (filtering) -> heat exchange device 15 -> first filter device 16 (backwashing) -> sewage reversing valve 144 -> sewage discharge tank 18. This process realizes online backwashing of the first filter device 16.

[0029] Through automatic switching between forward and reverse operation, wastewater system 1 achieves uninterrupted filtration and backwashing, ensuring the long-term stable operation of the heat exchange unit.

[0030] For details, please refer to Figure 1 and Figure 3 The water purification system 2 includes a water purification buffer tank 21, a water purification pump 22, a water purification flow direction switching valve group 23, and a hot water storage tank 24.

[0031] The clean water buffer tank 21 is used to store clean water. Its structure and material are similar to those of the sewage buffer tank 11, and it is usually a cylindrical stainless steel tank. The clean water pump 22 is a variable frequency pump, and its inlet is connected to the outlet of the clean water buffer tank 21. Like the sewage pump 13, it can also adjust its power according to the clean water flow rate requirements. The clean water pump 22 is generally a centrifugal pump, but other suitable pumps can also be used.

[0032] The clean water flow direction switching valve group 23 consists of a first clean water switching valve 231, a second clean water switching valve 232, a third clean water switching valve 233, and a fourth clean water switching valve 234 connected counterclockwise via pipelines. The outlet of the clean water pump 22 is connected to the pipeline between the first clean water switching valve 231 and the second clean water switching valve 232. These valves are also of the electric or pneumatic butterfly valve type, which can realize the switching of the clean water flow direction. The hot water storage tank 24 is used to store the hot water after heat exchange. It is generally a metal tank wrapped with insulation material, which can effectively reduce heat loss.

[0033] The combined logic of the clean water system 2 is as follows: clean water is transported from the clean water buffer tank 21 to the clean water flow switching valve group 23 via the clean water pump 22, then passes through the heat exchange device 15 to absorb the heat from the sewage, and finally enters the hot water storage tank 24. This combination enables the flow and heat exchange of clean water, working in conjunction with the sewage system 1 to efficiently recover waste heat from the sewage.

[0034] The working process of the water purification system is as follows: The function of the clean water system 2 is to absorb the heat released by the sewage and heat the cold water into hot water. Its flow direction switches synchronously with that of the sewage system 1 to maintain efficient countercurrent heat exchange at all times.

[0035] In coordination with forward operation: When the sewage system 1 is in forward operation, the second and fourth clean water reversing valves 232 and 234 of the clean water system 2 are opened. The clean water pump 22 draws cold water from the clean water buffer tank 21, which flows through the second clean water reversing valve 232 into the first clean water side interface 153 of the heat exchange device 15. After absorbing heat, the water flows out from the second clean water side interface 152 and then through the fourth clean water reversing valve 234 into the hot water storage tank 24.

[0036] Coordinated Reverse Operation: When wastewater system 1 switches to reverse operation, clean water system 2 switches synchronously. The system closes the second and fourth clean water reversing valves 232 and 234, and opens the first and third clean water reversing valves 231 and 233. At this time, the clean water flow path becomes: clean water pump 22 -> first clean water reversing valve 231 -> heat exchanger 15 (inlet from the second clean water side interface 154, outlet from the first clean water side interface 153) -> third clean water reversing valve 233 -> hot water storage tank 24.

[0037] By switching in the opposite direction to the flow of sewage, the hot and cold media are always in a counter-current state in the heat exchange device 15, ensuring the best heat exchange efficiency.

[0038] Specifically, please refer to Figure 1 , Figure 4 and Figure 5 The automatic dosing system 3 includes a solution tank 31, a dosing system inlet valve 32, a dosing system outlet valve 33, a first dosing pipeline valve 34, and a second dosing pipeline valve 35.

[0039] The solution tank 31 is a key piece of equipment for the safe and efficient preparation and dosing of reagents. Its components include: tank body 310, automatic stirrer 311, clean water inlet 312, solution outlet 313, drain port 314, dosing tank 318, sealing cover 319, manual valve 315, check valve 316 and overflow pipe 317.

[0040] The following is a detailed introduction to each component: Tank body 310, automatic stirrer 311 and related openings: Tank body 310 serves as the main body of solution tank 31. The top is equipped with automatic stirrer 311 and a clean water inlet 312, while the bottom has a solution outlet 313 and a drain outlet 314. Automatic stirrer 311 plays a crucial role in the preparation of the reagent, ensuring thorough mixing of the reagent and water, guaranteeing the uniformity of the solution, and ensuring effective subsequent dosing.

[0041] Dosing tank 318 and sealing cap 319: The dosing tank 318 is located inside the tank body 310 and adopts a steel filter screen structure. This structure can filter out insoluble impurities in the reagent, thereby preventing these impurities from entering downstream equipment and causing blockages. The sealing cap 319 on the upper part of the dosing tank 318 has a handle. This design makes it convenient for operators to open the cap to add reagents into the tank, and also facilitates the removal of the dosing tank for cleaning and maintenance, ensuring a smooth dosing process and cleanliness of the equipment.

[0042] Manual valve 315 and check valve 316: The drain port 314 is connected to the manual valve 315, and the outlet of the manual valve 315 is connected to the inlet of the check valve 316. The function of the manual valve 315 is to be manually opened by the operator when the system is shut down for a long period of time, so as to drain the solution in the tank 310 to the wastewater buffer tank 11, while keeping it closed during normal operation. The outlet of the check valve 316 is connected to the overflow port 112 of the wastewater buffer tank 11. Its main function is to prevent wastewater from the wastewater buffer tank 11 from flowing back into the solution tank 31, thereby avoiding contamination of the equipment and reagents.

[0043] Overflow pipe 317: The overflow pipe 317 is arranged in an inverted U-shape, with one end extending into the bottom of the tank 310 and the other end connected to the pipeline between the manual valve 315 and the check valve 316. When the liquid level in the solution tank 31 is too high or overpressure occurs, the excess cleaning fluid can be safely discharged into the sewage buffer tank 11 through the overflow pipe 317, ensuring the safe operation of the solution tank 31.

[0044] The dosing system inlet valve 32 is connected between the outlet of the clean water pump 22 and the clean water inlet 312 of the solution tank 31, and is used to control the flow rate of clean water entering the solution tank 31. The inlet of the dosing system outlet valve 33 is connected to the solution outlet 313 of the solution tank 31, and the outlet is connected to the inlet of the first dosing pipeline valve 34. The outlet of the first dosing pipeline valve 34 is connected to the pipeline between the sewage inlet valve 12 and the sewage pump 13. The inlet of the second dosing pipeline valve 35 is connected to the pipeline between the dosing system outlet valve 33 and the first dosing pipeline valve 34, and the outlet is connected to the pipeline between the second filter device 17 and the sewage flow direction switching valve group 14.

[0045] The automatic dosing system 3 operates as follows: when dosing is required, clean water enters the solution tank 31 through the dosing system inlet valve 32. An automatic stirrer 311 dissolves the cleaning agent, which is then injected into the wastewater system 1 through the dosing system outlet valve 33 and the dosing pipeline valve to clean the pipes and equipment. This combination enables automatic preparation and injection of cleaning agents, solving the problem of deep scaling or clogging that cannot be addressed by dynamic backwashing.

[0046] The automatic dosing system works as follows: The automatic dosing system 3 is used to handle deep scaling or clogging problems that cannot be solved by dynamic backwashing, and it is divided into two modes: online cleaning and offline cleaning.

[0047] Online intelligent cleaning: When the intelligent control system 4 determines that the pressure difference of the filter device cannot recover to 1.1 times or less of the clean state within a short period of time (e.g., 0.3 hours) after switching the flow direction, it indicates deep blockage, and the system will automatically start online cleaning. First, the inlet valve 32 of the dosing system is opened, and water is injected into the solution tank 31 by the clean water pump 22. At the same time, the automatic stirrer 311 is started to dissolve the agent in the dosing tank 318. When the solution tank level sensor 414 detects that the level has reached the standard, the system automatically opens the dosing system outlet valve 33 and the first dosing pipeline valve 34. The dissolved cleaning agent is injected into the sewage main pipeline of the heat exchanger unit by the sewage pump 13 to soften and clean the stubborn dirt in the pipes and equipment. The waste liquid after the reaction is discharged into the sewage discharge tank 18 along with the sewage. This process is carried out during the normal operation of the heat exchanger unit without interrupting the waste heat recovery.

[0048] Offline Intelligent Cleaning: When the heat exchanger unit is shut down for standby, the operator can activate the offline cleaning mode with a single button. The system first automatically prepares the cleaning solution (process as above). After preparation, the dosing system outlet valve 33, the first dosing pipeline valve 34, and the sewage reversing valve 141 are opened, and the sewage pump 13 is started to inject and fill the entire sewage side pipeline and equipment with the cleaning solution. After filling, the dosing system outlet valve 33 is closed, and the second dosing pipeline valve 35 is opened, forming a closed loop (sewage pump 13 -> sewage reversing valve 141 -> first filter device 16 -> heat exchange device 15 -> second filter device 17 -> second dosing pipeline valve 35 -> back to the inlet of sewage pump 13), using the cleaning solution to perform powerful circulating cleaning on the sewage side. When the intelligent control system 4 determines that cleaning is complete based on the pressure difference signal, the system automatically opens the sewage reversing valve 143 to discharge the waste liquid into the sewage discharge tank 18, completing the entire cleaning process.

[0049] The automatic dosing system 3 can automatically prepare and inject cleaning agents according to actual conditions during the operation of the heat exchanger unit to clean the system. Whether online or offline cleaning, it can effectively remove stubborn dirt from pipes and equipment, ensuring the normal operation of the heat exchanger unit. Compared with existing technologies, the addition of automatic dosing cleaning function improves the stability and efficiency of wastewater waste heat recovery.

[0050] For details, please refer to Figure 1-Figure 4 The intelligent control system 4 includes sensing components, including a first pressure transmitter 41 disposed between the sewage flow direction switching valve group 14 and the first filter device 16, a second pressure transmitter 42 disposed between the first filter device 16 and the heat exchange device 15 and a first temperature sensor 45 on the sewage side, a third pressure transmitter 43 disposed between the heat exchange device 15 and the second filter device 17 and a second temperature sensor 46 on the sewage side, a fourth pressure transmitter 44 disposed between the second filter device 17 and the sewage flow direction switching valve group 14, a sewage flow meter 49 disposed at the inlet end of the sewage discharge pool 18, a clean water flow meter 410 disposed at the inlet end of the hot water storage tank 24, a sewage buffer tank level sensor 411 disposed on the sewage buffer tank 11, a clean water buffer tank level sensor 412 disposed on the clean water buffer tank 21, a hot water storage tank level sensor 413 disposed on the hot water storage tank 24, and a solution tank level sensor 414 disposed on the solution tank 31.

[0051] The wastewater flow meter 49 is installed on the connecting pipe between the wastewater flow direction switching valve group and the wastewater discharge tank 18. The ingenious aspect of this location is that it measures wastewater that has been filtered by the filtration device, thereby effectively reducing the contamination and wear of the flow meter by impurities in the raw wastewater, and significantly improving the accuracy of the measurement and the long-term stability of the instrument.

[0052] Pressure transmitters are used to monitor the pressure difference before and after the filtration device in real time. Capacitive pressure transmitters are generally used, offering advantages such as high accuracy and stability. Temperature sensors are used to monitor the temperature of wastewater and clean water, typically using thermocouples or resistance temperature detectors (RTDs). Flow meters are used to measure the flow rate of wastewater and clean water; common types include electromagnetic flow meters. Level sensors are used to monitor the liquid level in each tank, generally using float-type level sensors. These sensors transmit data to the intelligent control system 4, which then performs logical judgments and controls based on this data.

[0053] The combined logic of the intelligent control system 4 is as follows: It collects data in real time from various sensors, determines the degree of blockage in the filter device based on pressure difference data, and controls the switching of the water flow direction in the wastewater system 1; it also evaluates the operating efficiency of the heat exchanger 15 based on temperature and flow data, and initiates an online chemical cleaning program when efficiency decreases or the filter device is in poor health. This combination enables intelligent control of the heat exchanger unit, ensuring its efficient and stable operation.

[0054] The working process of the intelligent control system is as follows: The intelligent control system 4 is the brain of the entire heat exchanger unit, responsible for monitoring, judging and making decisions to ensure that the unit operates fully automatically, efficiently and safely.

[0055] Status monitoring: The system collects data in real time through various sensors. Pressure transmitters 41, 42, 43, and 44 monitor the pressure drop of the filter device and heat exchanger 15; temperature sensors 45, 46, 47, and 48 monitor the inlet and outlet temperatures of sewage and clean water; flow meters 49 and 410 monitor the flow rate of the medium; and level sensors 411, 412, 413, and 414 monitor the liquid level in each tank.

[0056] Logical judgment and control: Dynamic backwashing decision: Based on the differential pressure data of the first pressure transmitter 41, the second pressure transmitter 42 or the third pressure transmitter 43 and the fourth pressure transmitter 44, the degree of clogging of the corresponding filter device is determined, and the switching command for forward or reverse operation is automatically executed to realize dynamic backwashing.

[0057] Health status assessment and cleaning decision: The system combines data from temperature sensors and flow meters to calculate the heat released by wastewater and the heat absorbed by clean water, thereby assessing the operating efficiency of heat exchanger 15. When the efficiency drops significantly, or when dynamic backwashing fails to effectively remove blockages, the system determines that the unit has severe scaling and automatically triggers the online intelligent cleaning program.

[0058] Safety and Optimized Control: Based on signals from each liquid level sensor, the system controls the start and stop of the water pump and the opening and closing of valves to prevent the water pump from running dry or the tank from overflowing, ensuring that all rotating equipment is always operating under optimal conditions.

[0059] Human-machine interaction: Provides an operation interface that allows operators to start or stop the unit with one click, and can manually trigger the offline intelligent cleaning mode for easy maintenance.

[0060] The implementation principle of this embodiment is as follows: This intelligent heat exchange unit achieves efficient recovery of waste heat from wastewater through the coordinated operation of wastewater system 1, clean water system 2, and intelligent control system 4. Wastewater system 1 utilizes the switching and backwashing functions of the filtration device to reduce the impact of impurities on heat exchange; clean water system 2 works in conjunction with wastewater system 1 to heat cold water into hot water. Intelligent control system 4 automatically controls the switching of water flow direction and the cleaning program through real-time monitoring and logical judgment, ensuring the long-term stable operation of the system. Compared with existing technologies, this unit solves the problems of easy scaling, frequent clogging, and difficult maintenance of conventional heat exchange devices, improves the utilization rate of waste heat from wastewater, and has significant advantages and practicality.

[0061] Preferably, the side wall of the filter device in the wastewater system 1 is equipped with a detachable glass observation window. This detachable glass observation window is typically made of high-strength tempered glass and is generally round or square in shape. Through the observation window, operators can directly observe the accumulation of impurities inside the filter device, promptly identify problems, and take appropriate action. In some cases, if the glass observation window is damaged, it can be easily disassembled and replaced.

[0062] The implementation principle of this embodiment is as follows: the detachable glass observation window facilitates the operator's observation of the internal condition of the filtration device, enabling timely detection of problems such as clogging, and allowing for proactive measures to be taken, further improving the system's reliability and maintenance efficiency. Compared to existing technologies, this increases the convenience of observing the internal condition of the filtration device, reduces system failures caused by clogging, and improves the efficiency of wastewater waste heat recovery.

[0063] The beneficial effects of the technical solution provided by this invention include: (1) When the heat exchange unit is in operation, it can filter the incoming sewage in real time and automatically identify slight scaling or blockage, and execute the automatic backwash command without stopping the machine. This can reduce the possibility of scaling in the pipes and equipment, avoid blockage, and thus ensure the long-term stable and reliable operation of the heat exchange unit. (2) When the system determines that there is severe scaling or blockage, it will automatically start the online intelligent cleaning mode. In addition, when the equipment is shut down for standby, the operator can start the offline intelligent cleaning mode with one click, which solves the problem of difficult maintenance of traditional heat exchange units. (3) Since automatic backwashing or online intelligent cleaning mode can be carried out without interrupting waste heat recovery, the unit realizes dynamic protection of the heat exchange unit, thereby improving the utilization rate of the equipment while recovering waste heat from sewage in a high-efficiency manner.

[0064] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A smart heat exchanger unit for wastewater waste heat recovery, characterized in that, The system includes a wastewater system for guiding wastewater flow, a clean water system for guiding clean water flow and exchanging heat with the wastewater, and a smart control system. The wastewater system contains at least two sets of filtration devices that can switch between filtration and backwashing states. The smart control system is configured to: (a) Real-time monitoring of the first pressure difference before and after the filter device currently in the filtration state; (b) When the first pressure difference reaches a preset first threshold, the sewage system is automatically controlled to switch the water flow direction, so that the filter device in the filtration state switches to the backwash state. (c) After switching the water flow direction, continue to monitor the health status of the backwashed filter device. If it fails to recover to a preset health status within the preset first time period, the online dosing cleaning program will be automatically started. Cleaning agent will be injected into the sewage system while the smart heat exchanger unit for waste heat recovery is continuously recovering waste heat.

2. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 1, characterized in that, The wastewater system includes: Wastewater buffer tank, which is equipped with a wastewater outlet; The sewage pump has its inlet connected to the sewage outlet of the sewage buffer tank via a sewage inlet valve. The sewage flow direction switching valve group consists of a sewage reversing first valve, a sewage reversing second valve, a sewage reversing third valve, and a sewage reversing fourth valve connected clockwise by a pipeline. The outlet of the sewage pump is connected to the pipeline between the sewage reversing first valve and the sewage reversing second valve. Heat exchange device; The first filtration device has one end connected to the pipeline between the first sewage reversing valve and the fourth sewage reversing valve, and the other end connected to the first sewage side interface of the heat exchange device. The second filtration device has one end connected to the second sewage side interface of the heat exchange device, and the other end connected to the pipeline between the sewage reversing second valve and the sewage reversing third valve. A sewage discharge tank is connected to the pipeline between the third sewage reversing valve and the fourth sewage reversing valve.

3. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 2, characterized in that, Both the first and second filter devices have detachable glass observation windows on their side walls.

4. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 2, characterized in that, The water purification system includes: Clear water buffer tank; A clean water pump, the inlet of which is connected to the outlet of the clean water buffer tank; A clean water flow direction switching valve group, which consists of a first clean water switching valve, a second clean water switching valve, a third clean water switching valve, and a fourth clean water switching valve connected counterclockwise through a pipeline, and the outlet of the clean water pump is connected to the pipeline between the first clean water switching valve and the second clean water switching valve. A hot water storage tank, wherein the hot water storage tank is connected to the pipeline between the third water diversion valve and the fourth water diversion valve; The first clean water side interface of the heat exchange device is connected to the pipeline between the second clean water reversing valve and the third clean water reversing valve; The second clean water side interface of the heat exchange device is connected to the pipeline between the first clean water reversing valve and the fourth clean water reversing valve.

5. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 1, characterized in that, It also includes an automated dosing system, which comprises: The solution tank includes a tank body, an automatic stirrer and a clean water inlet located on the top of the tank body, a solution outlet and a drain outlet located at the bottom of the tank body, and a dosing tank with a steel filter structure located inside the tank body. A dosing system inlet valve is connected between the outlet of the clean water pump and the clean water inlet of the solution tank; The dosing system outlet valve has its inlet connected to the solution outlet of the solution tank, and its outlet connected to the inlet of the first dosing pipeline valve. The first dosing pipeline valve, the outlet of the first dosing pipeline valve is connected to the pipeline between the sewage inlet valve and the sewage pump; The second dosing line valve has its inlet connected to the pipeline between the dosing system outlet valve and the first dosing line valve, and its outlet connected to the pipeline between the second filter device and the sewage flow direction switching valve group.

6. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 5, characterized in that, The intelligent control system includes a sensing component, which includes: A first pressure transmitter is installed between the sewage flow direction switching valve group and the first filter device; A second pressure transmitter and a first temperature sensor on the wastewater side are installed between the first filtration device and the heat exchange device. A third pressure transmitter and a second temperature sensor on the wastewater side are installed between the heat exchange device and the second filter device. A fourth pressure transmitter is installed between the second filtration device and the sewage flow direction switching valve group; A wastewater flow meter is installed at the inlet end of the wastewater discharge tank; A clean water flow meter installed at the inlet of the hot water storage tank; A sewage buffer tank level sensor is installed on the sewage buffer tank; A water level sensor is installed on the water buffer tank. A hot water storage tank level sensor is installed on the hot water storage tank; And a solution tank level sensor installed on the solution tank.

7. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 1, characterized in that, The first threshold is 1.3-1.8 times the pressure difference of the filter device in the initial clean state.

8. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 7, characterized in that, The first threshold is 1.5 times the pressure difference of the filter device in its initial clean state.

9. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 1, characterized in that, The healthy state is defined as a pressure difference across the filter device that is less than 1.05-1.15 times its pressure difference in the initial clean state.

10. The intelligent heat exchanger unit for wastewater waste heat recovery according to claim 9, characterized in that, The first time period is 0.1-0.5 hours.

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