Excess waste heat recovery and utilization system

Abstract

This utility model relates to the field of waste heat recovery technology, and in particular to a waste heat recovery and utilization system. It includes at least two waste hot water loops and N waste heat circulation units, where N≥2. The N waste heat circulation units include a first waste heat circulation unit, ..., an Nth waste heat circulation unit, the number of which corresponds to the number of waste hot water loops. The first waste heat circulation unit includes at least one heat exchanger group, which includes at least one plate heat exchanger. The Nth waste heat circulation unit includes at least one magnetic levitation centrifugal heat pump group, which includes at least one magnetic levitation centrifugal heat pump, and the magnetic levitation centrifugal heat pump includes a magnetic levitation variable frequency compressor. This utility model recovers waste heat from at least two low-temperature waste hot water systems by setting up N waste heat circulation units, thereby achieving the recovery of low-temperature waste hot water to produce high-temperature heating water to meet municipal heating and long-distance transportation requirements.

Description

Technical Field

[0001] This utility model relates to the field of waste heat recovery technology, and in particular to a waste heat recovery and utilization system. Background Technology

[0002] In the early stages, waste heat or cold energy was directly emitted, causing localized heat island effects or cold pollution. Traditional waste heat recovery systems rely on a single energy source, resulting in high operating costs and large carbon emissions. They also suffer from problems such as unreasonable heat exchange design and large heat losses, leading to insufficient extraction or low transfer efficiency of waste heat. They only recover high-temperature waste heat while neglecting medium- and low-temperature waste heat, or lack tiered utilization methods. Waste heat recovery systems using conventional heat pumps suffer from high frictional losses and low part-load efficiency, resulting in low operating energy efficiency ratios. In addition, existing waste heat recovery systems struggle to effectively utilize low-grade heat sources. Utility Model Content

[0003] The technical problem to be solved by this utility model is: in order to solve the problems of large heat loss, low operating energy efficiency ratio and difficulty in effectively utilizing low-grade heat sources in the existing technology mentioned above, a waste heat recovery and utilization system is provided. Through efficient multi-stage heat recovery and utilization, flexible heat pump group configuration, stable circulation pump support, optimized heat exchange channel design and expandable heat pump group scale, etc., the system achieves efficient recovery and utilization of waste heat.

[0004] The technical solution adopted by this utility model to solve its technical problem is: a waste heat recovery and utilization system, including at least two waste water circuits, and N waste heat circulation units, where N≥2. The N waste heat circulation units include a first waste heat circulation unit, ..., an Nth waste heat circulation unit, the number of which is consistent with the number of waste water circuits. The first waste heat circulation unit includes at least one heat exchanger group, the heat exchanger group includes at least one plate heat exchanger, and the Nth waste heat circulation unit includes at least one magnetic levitation centrifugal heat pump group, the magnetic levitation centrifugal heat pump group includes at least one magnetic levitation centrifugal heat pump, and the magnetic levitation centrifugal heat pump includes a magnetic levitation variable frequency compressor.

[0005] By setting up at least two waste heat water loops, the system can simultaneously treat waste heat wastewater from multiple sources, improving its parallel processing capacity and flexibility. Employing N≥2 waste heat circulation units, each corresponding to one waste heat water loop, enables modular management, facilitating maintenance and expansion. The first waste heat circulation unit uses a plate heat exchanger group for primary heat exchange, while the Nth unit uses a magnetic levitation centrifugal heat pump group for advanced heat recovery, forming a tiered energy utilization and improving overall efficiency. The magnetic levitation centrifugal heat pump group utilizes a magnetic levitation variable frequency compressor, reducing mechanical friction losses, improving the energy efficiency ratio, and simultaneously reducing noise and maintenance costs. The configuration of at least one heat exchanger group and a magnetic levitation centrifugal heat pump group allows for flexible configuration of the number of devices according to actual needs, adapting to waste heat recovery scenarios of different scales.

[0006] This invention, by setting at least two waste heat water loops, allows the system to simultaneously treat waste heat wastewater from multiple sources. It employs N≥2 waste heat circulation units, each corresponding to one waste heat water loop. The first waste heat circulation unit includes at least a plate heat exchanger assembly for higher-temperature heat recovery, while the Nth waste heat circulation unit includes at least a magnetic levitation centrifugal heat pump assembly for medium- and low-temperature heat recovery, forming a stepped energy utilization and significantly improving the overall system efficiency. The magnetic levitation centrifugal heat pump assembly utilizes a magnetic levitation variable frequency compressor, which can significantly reduce mechanical friction losses, effectively improve the energy efficiency ratio, and significantly reduce operating noise and maintenance costs. The setting of at least one heat exchanger and magnetic levitation centrifugal heat pump assembly allows for flexible configuration of the number of devices according to actual needs, adapting to different scales of waste heat recovery scenarios. To produce high-temperature heating water (municipal water) by recovering low-temperature waste heat water, multiple low-temperature waste heat water loops (circulating water) are required, necessitating the setting of N waste heat circulation units. A single low-temperature waste heat water loop is insufficient to meet heating demands. Employing a magnetically levitated centrifugal heat pump can solve the frequency conversion difficulties caused by low-temperature waste water, ensuring stable system operation and preventing surge phenomena. With the system's tiered treatment of waste heat at different temperature levels, it can maximize the cascade utilization of energy, further improving energy recovery efficiency and adapting to various scales of medium- and low-temperature waste heat recovery scenarios.

[0007] According to one embodiment of the present invention, all waste heat circulation units are independent on the waste water side and are connected in series on the municipal water side.

[0008] All waste heat circulation units operate independently on the waste hot water side, fundamentally avoiding mutual interference between different loops. This ensures that the water quality, temperature, and other characteristics of the waste hot water in each loop remain stable and unaffected by fluctuations in other loops. Simultaneously, each waste heat circulation unit can be individually controlled according to its own characteristics; the operating frequency of the corresponding heat pump can be adjusted for waste hot water with different temperatures and flow rates. There is no series connection between the waste heat circulation units, and the adjustments to their flow rate, temperature, and other parameters do not interfere with each other. This simplifies the control logic and facilitates precise management of the waste hot water side. When fluctuations occur in some loops, only the corresponding waste heat circulation unit needs adjustment, without affecting the normal operation of other waste heat circulation units. The temperature of the waste hot water in the first waste heat circulation unit is greater than or equal to the temperature of the waste hot water in the second waste heat circulation unit, the temperature of the waste hot water in the second waste heat circulation unit is greater than or equal to the temperature of the waste hot water in the third waste heat circulation unit, and so on, until the temperature of the waste hot water in the (N-1)th waste heat circulation unit is greater than or equal to the temperature of the waste hot water in the Nth waste heat circulation unit. The series connection on the municipal water side enables energy transfer in stages. The initially cooler municipal water first comes into contact with higher-grade waste heat, rapidly absorbing heat and rising in temperature. Then, in the higher-temperature section, it comes into contact with lower-grade waste heat, continuing to absorb heat efficiently. This process significantly improves overall heat exchange efficiency. All waste heat circulation units are connected in series on the municipal water side, allowing the municipal water (heating water) to achieve tiered heating through a series loop. Each stage can fully absorb heat from its corresponding waste heat circulation unit.

[0009] According to one embodiment of the present invention, the magnetic levitation centrifugal heat pump group includes two magnetic levitation centrifugal heat pumps, the condensers of the two magnetic levitation centrifugal heat pumps are connected in parallel, and the evaporators of the two magnetic levitation centrifugal heat pumps are connected in parallel.

[0010] Two magnetic levitation centrifugal heat pumps are connected in parallel, which can directly increase the system's heating capacity and meet high-flow heating demands. In parallel operation, the system can still function even if one heat pump fails, improving reliability. Parallel evaporators and condensers balance the load on the two heat pumps, extending equipment lifespan, and allow for flexible start-up and shutdown of one pump under partial load conditions to save energy.

[0011] According to one embodiment of the present invention, the first waste heat circulation unit further includes a second cooling circulation pipeline, which is connected to the waste water side of the heat exchanger group of the first waste heat circulation unit.

[0012] The second cooling circulation pipeline absorbs heat from the waste hot water through the heat exchanger group, rapidly raising the temperature of the heating water and improving the heat exchange efficiency.

[0013] According to one embodiment of the present invention, the Nth waste heat circulation unit further includes a third cooling circulation pipeline, which is connected to the municipal water side of the magnetic levitation centrifugal heat pump unit of the Nth waste heat circulation unit.

[0014] The third cooling circulation pipeline uses a heat pump to reheat the municipal water to produce high-temperature heating water.

[0015] According to one embodiment of the present invention, the waste heat recovery and utilization system further includes a second heating circulation pipeline, which is respectively connected to the municipal water side of the first waste heat circulation unit, ..., the Nth waste heat circulation unit.

[0016] According to one embodiment of the present invention, the heat exchanger group of the second waste heat circulation unit includes a third plate heat exchanger, a first magnetic levitation centrifugal heat pump group and a second magnetic levitation centrifugal heat pump group; the magnetic levitation centrifugal heat pump group of the Nth waste heat circulation unit includes a first-stage magnetic levitation centrifugal heat pump group, a second-stage magnetic levitation centrifugal heat pump group, a third-stage magnetic levitation centrifugal heat pump group, a fourth-stage magnetic levitation centrifugal heat pump group and a fifth-stage magnetic levitation centrifugal heat pump group.

[0017] The second waste heat circulation unit uses a combination of plate heat exchangers and magnetic levitation centrifugal heat pumps for heat exchange. Plate heat exchangers are used for the medium-temperature range of hot water, while magnetic levitation centrifugal heat pumps are used for the lower-temperature range. This configuration can avoid the waste of waste heat in the low-temperature range and has high heat exchange efficiency. The magnetic levitation centrifugal heat pump group of the Nth waste heat circulation unit adopts a five-stage magnetic levitation centrifugal heat pump to achieve deep heat extraction, covering a wide temperature range of waste heat. The multi-stage heat pump group design allows for flexible adjustment of the number of heat pumps according to the waste heat quality.

[0018] According to one embodiment of the present invention, N=3.

[0019] According to one embodiment of the present invention, the heat exchanger group of the second waste heat circulation unit further includes a second plate heat exchanger and a first heating circulation pipeline connected to the second plate heat exchanger. The second plate heat exchanger is for plate heat exchange. The municipal water side of the second plate heat exchanger is connected through the first heating circulation pipeline, and the waste water side of the second plate heat exchanger is connected through the first cooling circulation pipeline.

[0020] The second plate heat exchanger serves as a backup. When the return water is unstable, the system switches to the second plate heat exchanger to stabilize the low-temperature return water temperature, ensuring the balance of the factory's production water system circulation, stable energy consumption, and equipment safety, thus ensuring normal production.

[0021] According to one embodiment of the present invention, the heat exchanger group of the first waste heat circulation unit includes a first plate heat exchanger and a second cooling circulation pipeline connected to the first plate heat exchanger. The municipal water side of the first plate heat exchanger is connected through a first heating circulation pipeline, and the waste water side of the first plate heat exchanger is connected through a second cooling circulation pipeline.

[0022] The first plate heat exchanger prioritizes handling high-temperature waste heat, which is then rapidly cooled via the second cooling circulation line. The first heating circulation line directly transfers some of the heat to the municipal water side, reducing the load on the high-order heat pump.

[0023] According to one embodiment of the present invention, a third plate heat exchanger, a first magnetic levitation centrifugal heat pump group and a second magnetic levitation centrifugal heat pump group connected in parallel are sequentially connected to the first cooling circulation pipeline. The first plate heat exchanger is connected to the second cooling circulation pipeline. A first-stage magnetic levitation centrifugal heat pump group and a second-stage magnetic levitation centrifugal heat pump group are sequentially connected to the third cooling circulation pipeline. The second plate heat exchanger is connected to the first heating circulation pipeline. The second heating circulation pipeline is sequentially connected to the first plate heat exchanger, the third plate heat exchanger, the first magnetic levitation centrifugal heat pump group, the second magnetic levitation centrifugal heat pump group, a five-stage magnetic levitation centrifugal heat pump group, a four-stage magnetic levitation centrifugal heat pump group, a three-stage magnetic levitation centrifugal heat pump group, a second-stage magnetic levitation centrifugal heat pump group, and a first-stage magnetic levitation centrifugal heat pump group.

[0024] Clearly define the connection sequence of each pipeline to reduce ineffective heat loss. Municipal water sequentially absorbs heat from the first plate heat exchanger, the third plate heat exchanger, the first magnetic levitation centrifugal heat pump unit, the second magnetic levitation centrifugal heat pump unit, the second-stage magnetic levitation centrifugal heat pump unit, and the first-stage magnetic levitation centrifugal heat pump unit in the second heating pipeline, achieving a step-by-step temperature increase.

[0025] According to one embodiment of the present invention, the third plate heat exchanger includes a heat exchange channel one and a heat exchange channel two. The inlet of the heat exchange channel one is connected to the outlet of the first circulating pump, and the outlet of the heat exchange channel one is connected to the inlet of the magnetic levitation centrifugal heat pump evaporator in the first magnetic levitation centrifugal heat pump group and the second magnetic levitation centrifugal heat pump group respectively. The outlet of the evaporator is connected to the second plate heat exchanger.

[0026] The dual-channel design of the third plate heat exchanger diverts the waste hot water to the heat pump evaporator, optimizing the heat transfer path. The first circulation pump ensures that the waste hot water enters the evaporator stably, avoiding flow fluctuations.

[0027] According to one embodiment of the present invention, the first plate heat exchanger includes heat exchange channel A and heat exchange channel B. The inlet of heat exchange channel A is connected to the inlet of the second cooling circulation pipeline, and the outlet of heat exchange channel A is connected to the return port of the second cooling circulation pipeline. The inlet of heat exchange channel B is connected to the outlet of the third circulation pump, and the outlet of heat exchange channel B is connected to the inlet of heat exchange channel two of the third plate heat exchanger. The outlet of heat exchange channel two is sequentially connected to the inlet of the magnetic levitation centrifugal heat pump condenser in the first magnetic levitation centrifugal heat pump group, the second magnetic levitation centrifugal heat pump group, the second-stage magnetic levitation centrifugal heat pump group, and the first-stage magnetic levitation centrifugal heat pump group. The outlet of the condenser is connected to the inlet of the fourth circulation pump.

[0028] The first plate heat exchanger processes low-temperature waste heat through heat exchange channel A, while heat exchange channel B is linked with subsequent equipment to fully extract residual heat. The third and fourth circulating pumps coordinate the flow of municipal water to ensure efficient heat output from the heat pump condenser side.

[0029] The beneficial effects of this utility model are: (1) This utility model recovers the waste heat from at least two low-temperature waste waters by setting up N waste heat circulation units, so as to realize the recovery of low-temperature waste water to produce high-temperature heating water to meet the requirements of municipal heating and long-distance transmission; it can ensure that waste heat of different grades is effectively absorbed and utilized, from high-temperature waste heat above 80℃ to low-temperature waste heat below 30℃, all of which can be absorbed step by step; the temperature of the waste water in the first waste heat circulation unit is greater than or equal to the temperature of the waste water in the Nth waste heat circulation unit, the first waste heat circulation unit includes at least a plate heat exchanger group for higher temperature heat recovery, and the Nth waste heat circulation unit includes at least a magnetic levitation centrifugal heat pump group for lower medium and low temperature heat recovery, forming a stepped energy utilization, which significantly improves the overall heat exchange efficiency of the system.

[0030] (2) By setting up a multi-stage magnetic levitation centrifugal heat pump, the heating water temperature can be stepped up to 90°C or above to meet the requirements of long-distance heating. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Figure 1 This is a process flow diagram of the waste heat recovery and utilization system of Embodiment 1 of this utility model.

[0033] Figure 2 This is a process flow diagram of the cooling circulation pipeline in Embodiment 1 of this utility model.

[0034] Figure 3 This is a process flow diagram of the heating circulation pipeline in Embodiment 1 of this utility model.

[0035] Figure 4 This is a process flow diagram of the waste heat recovery and utilization system of Embodiment 2 of this utility model.

[0036] Figure 5 This is a process flow diagram of the cooling circulation pipeline in Embodiment 2 of this utility model.

[0037] In the diagram: 100, First waste heat circulation unit; 200, Second waste heat circulation unit; 300, Third waste heat circulation unit; 1, First plate heat exchanger; 101, Heat exchange channel A; 102, Heat exchange channel B; 2, Second plate heat exchanger; 21, Heat exchange channel I; 22, Heat exchange channel II; 3, Third plate heat exchanger; 31, Heat exchange channel one; 32, Heat exchange channel two; 4, First magnetic levitation centrifugal heat pump unit; 5, Second magnetic levitation centrifugal heat pump unit; 6, First-stage magnetic levitation centrifugal heat pump unit; 7, Second-stage magnetic levitation centrifugal heat pump unit; 8. First cooling circulation pipeline; 9. Second cooling circulation pipeline; 10. Third cooling circulation pipeline; 11. First heating circulation pipeline; 12. Second heating circulation pipeline; 13. First circulation pump; 14. Second circulation pump; 15. Sludge separator; 16. Third circulation pump; 17. Fourth circulation pump; 18. Three-stage magnetic levitation centrifugal heat pump unit; 19. Four-stage magnetic levitation centrifugal heat pump unit; 20. Five-stage magnetic levitation centrifugal heat pump unit. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0039] Example 1 like Figure 1 As shown (the flowchart is too long and is therefore divided into two sections, with dashed lines indicating connections), a waste heat recovery system includes at least two waste water loops and N waste heat circulation units, where N ≥ 2. The N waste heat circulation units include a first waste heat circulation unit 100, ..., an Nth waste heat circulation unit, with the number of units matching the number of waste water loops. The first waste heat circulation unit 100 includes at least one heat exchanger group, which includes at least one plate heat exchanger. The Nth waste heat circulation unit includes at least one magnetic levitation centrifugal heat pump group, which includes at least one magnetic levitation centrifugal heat pump, which includes a magnetic levitation variable frequency compressor. All waste heat circulation units are independent on the waste water side and connected in series on the municipal water side. The magnetic levitation centrifugal heat pump group includes two magnetic levitation centrifugal heat pumps, with their condensers connected in parallel and their evaporators connected in parallel. The first waste heat circulation unit 100 also includes a second cooling circulation pipe 9, which is connected to the waste water side of the heat exchanger group of the first waste heat circulation unit 100.

[0040] The Nth waste heat circulation unit also includes a third cooling circulation pipe 10, which is connected to the municipal water side of the magnetic levitation centrifugal heat pump unit of the Nth waste heat circulation unit.

[0041] The waste heat recovery and utilization system also includes a second heating circulation pipeline 12, which is connected to the municipal water side of the first waste heat circulation unit 100, ..., the Nth waste heat circulation unit respectively.

[0042] The heat exchanger assembly of the second waste heat circulation unit 200 includes a third plate heat exchanger 3, a first magnetic levitation centrifugal heat pump assembly 4, and a second magnetic levitation centrifugal heat pump assembly 5; the magnetic levitation centrifugal heat pump assembly of the Nth waste heat circulation unit includes a first-stage magnetic levitation centrifugal heat pump assembly 6, a second-stage magnetic levitation centrifugal heat pump assembly 7, a third-stage magnetic levitation centrifugal heat pump assembly 18, a fourth-stage magnetic levitation centrifugal heat pump assembly 19, and a fifth-stage magnetic levitation centrifugal heat pump assembly 20. In this embodiment, N=3, and the Nth waste heat circulation unit is the third waste heat circulation unit 300.

[0043] The heat exchanger group of the first waste heat circulation unit 100 includes a first plate heat exchanger 1 and a second cooling circulation pipeline 9 connected to the first plate heat exchanger 1. The municipal water side of the first plate heat exchanger 1 is connected through the second heating circulation pipeline 12, and the waste water side of the first plate heat exchanger 1 is connected through the second cooling circulation pipeline 9.

[0044] The first cooling circulation pipeline 8 is connected in sequence to the third plate heat exchanger 3, the first magnetic levitation centrifugal heat pump group 4 and the second magnetic levitation centrifugal heat pump group 5 connected in parallel. The second cooling circulation pipeline 9 is connected to the first plate heat exchanger 1. The third cooling circulation pipeline 10 is connected in sequence to the first-stage magnetic levitation centrifugal heat pump group 6, the second-stage magnetic levitation centrifugal heat pump group 7, the third-stage magnetic levitation centrifugal heat pump group 18, the fourth-stage magnetic levitation centrifugal heat pump group 19 and the fifth-stage magnetic levitation centrifugal heat pump group 20. The second heating circulation pipeline 12 is connected in sequence to the first plate heat exchanger 1, the third plate heat exchanger 3, the first magnetic levitation centrifugal heat pump group 4, the second magnetic levitation centrifugal heat pump group 5, the fifth-stage magnetic levitation centrifugal heat pump group 20, the fourth-stage magnetic levitation centrifugal heat pump group 19, the third-stage magnetic levitation centrifugal heat pump group 18, the second-stage magnetic levitation centrifugal heat pump group 7 and the first-stage magnetic levitation centrifugal heat pump group 6. The inlet of the first cooling circulation pipeline 8 is connected to the first circulation pump 13, the inlet of the third cooling circulation pipeline 10 is connected to the second circulation pump 14, the inlet of the second heating circulation pipeline 12 is connected to the dirt remover 15 and the third circulation pump 16 in sequence, and its outlet is connected to the fourth circulation pump 17.

[0045] like Figure 2As shown, the first magnetic levitation centrifugal heat pump group 4 is equipped with three magnetic levitation centrifugal heat pumps connected in parallel, and the second magnetic levitation centrifugal heat pump group 5 is equipped with four magnetic levitation centrifugal heat pumps connected in parallel. The third plate heat exchanger 3 includes a heat exchange channel 1 31 and a heat exchange channel 2 32. The inlet of the heat exchange channel 1 31 is connected to the outlet of the first circulating pump 13, and the outlet of the heat exchange channel 1 31 is connected to the inlet of the evaporator of the magnetic levitation centrifugal heat pump in the first magnetic levitation centrifugal heat pump group 4 and the second magnetic levitation centrifugal heat pump group 5, respectively. The outlet of the evaporator is connected to the first cooling circulation pipeline 8.

[0046] The first plate heat exchanger 1 includes a heat exchange channel A101 and a heat exchange channel B102. The inlet of heat exchange channel A101 is connected to the inlet of the second cooling circulation pipeline 9, and the outlet of heat exchange channel A101 is connected to the return port of the second cooling circulation pipeline 9. Figure 1 The inlet of heat exchange channel B102 is connected to the outlet of the third circulating pump 16. The outlet of heat exchange channel B102 is connected to the inlet of heat exchange channel 32 of the third plate heat exchanger 3. The outlet of heat exchange channel 32 is connected in sequence to the inlet of the magnetic levitation centrifugal heat pump condenser in the first magnetic levitation centrifugal heat pump group 4, the second magnetic levitation centrifugal heat pump group 5, the fifth-stage magnetic levitation centrifugal heat pump group 20, the fourth-stage magnetic levitation centrifugal heat pump group 19, the third-stage magnetic levitation centrifugal heat pump group 18, the second-stage magnetic levitation centrifugal heat pump group 7 and the first-stage magnetic levitation centrifugal heat pump group 6. The outlet of its condenser is connected to the inlet of the fourth circulating pump 17.

[0047] like Figure 3 As shown, the first-stage magnetic levitation centrifugal heat pump group 6, the second-stage magnetic levitation centrifugal heat pump group 7, and the third-stage magnetic levitation centrifugal heat pump group 18 are each equipped with 4 magnetic levitation centrifugal heat pumps connected in parallel, and the fifth-stage magnetic levitation centrifugal heat pump group 20 and the fourth-stage magnetic levitation centrifugal heat pump group 19 are each equipped with 3 magnetic levitation centrifugal heat pumps connected in parallel.

[0048] The outlet of the second circulation pump 14 is connected to the inlet of the magnetic levitation centrifugal heat pump evaporator in the first-stage magnetic levitation centrifugal heat pump group 6 and the second-stage magnetic levitation centrifugal heat pump group 7, respectively. The outlet of its evaporator is connected to the inlet of the magnetic levitation centrifugal heat pump evaporator in the fifth-stage magnetic levitation centrifugal heat pump group 20, the fourth-stage magnetic levitation centrifugal heat pump group 19 and the third-stage magnetic levitation centrifugal heat pump group 18, respectively. The outlet of its evaporator is connected to the return port of the third cooling circulation pipeline 10.

[0049] In this embodiment, the inlet of the first cooling circulation pipeline 8 is connected to 50°C heat source water, and its return outlet outputs 35°C return water. The inlet of the second cooling circulation pipeline 9 is connected to 40°C heat source water, and its return outlet outputs 32°C return water. The inlet of the third cooling circulation pipeline 10 is connected to 48°C heat source water, and its return outlet outputs 40°C return water. The inlet of the second heating circulation pipeline 12 is connected to 30°C municipal return water, and its output is municipal water supply at 88.2°C. The first cooling circulation pipeline 8, the second cooling circulation pipeline 9, the third cooling circulation pipeline 10, and the second heating circulation pipeline 12 operate simultaneously.

[0050] 50℃ heat source water enters the third plate heat exchanger 3 via the first circulation pump 13 and is cooled to 42℃. The 42℃ water then enters the magnetic levitation centrifugal heat pump evaporators in the first magnetic levitation centrifugal heat pump group 4 and the second magnetic levitation centrifugal heat pump group 5, where it is cooled to 35℃. The 35℃ water exits each evaporator and returns to the return port of the first cooling circulation pipeline 8. 40℃ heat source water enters the first plate heat exchanger 1 for heat exchange and is cooled to 32℃, then returns to the return port of the second cooling circulation pipeline 9. The 48℃ heat source water enters the evaporators of the first-stage magnetic levitation centrifugal heat pump group 6 and the second-stage magnetic levitation centrifugal heat pump group 7 via the fourth circulation pump 17 for heat exchange and cooling to 44.3℃. The 44.3℃ water then enters the evaporators of the third-stage magnetic levitation centrifugal heat pump group 18, the fourth-stage magnetic levitation centrifugal heat pump group 19 and the fifth-stage magnetic levitation centrifugal heat pump group 20 for cooling to 40℃. The 40℃ water exits from each evaporator and is then combined and returned to the return port of the third cooling circulation pipeline 10.

[0051] Meanwhile, the 30℃ municipal return water, after passing through the sludge separator 15 and being pressurized by the third circulation pump 16, enters the first plate heat exchanger 1 for heat exchange and is heated to 36.8℃, then passes through the third plate heat exchanger 3 for heat exchange and is heated to 45.5℃, then enters the magnetic levitation centrifugal heat pump condenser of the first magnetic levitation centrifugal heat pump group 4 for heat exchange and is heated to 49.8℃, then enters the magnetic levitation centrifugal heat pump condenser of the second magnetic levitation centrifugal heat pump group 5 for heat exchange and is heated to 56℃, and finally enters the magnetic levitation centrifugal heat pump condenser of the fifth-stage magnetic levitation centrifugal heat pump group 20 for heat exchange and is heated to 56℃. The water temperature rises to 62°C, then to 67.7°C in the condenser of the fourth-stage magnetic levitation centrifugal heat pump group 19, then to 75.1°C in the condenser of the third-stage magnetic levitation centrifugal heat pump group 18, then to 82.1°C in the condenser of the second-stage magnetic levitation centrifugal heat pump group 7, and finally to 88.7°C in the condenser of the first-stage magnetic levitation centrifugal heat pump group 6. Finally, the water is combined with the temperature of the water by the second circulation pump 14 and output to the municipal water supply pipe.

[0052] This embodiment of the multi-stage waste heat recovery and utilization system achieves efficient cascade recovery and utilization of industrial waste heat through the coordinated design of multi-stage plate heat exchangers and magnetic levitation centrifugal heat pump units, combined with intelligent circulation pipeline layout. Specifically: I. Maximizing Energy Recovery Efficiency The first circulation of medium and low temperature waste water (50℃→35℃): The industrial waste water at 50℃ is cooled down to 35℃ through the first cooling circulation pipeline 8 in series with the third plate heat exchanger 3, the first magnetic levitation centrifugal heat pump group 4 and the second magnetic levitation centrifugal heat pump group 5, and the heat is recovered for the heating of municipal water supply (30℃→88.7℃). The second circulation of medium-low temperature waste hot water (48℃→40℃): The third cooling circulation pipeline 10 adopts a first-stage magnetic levitation centrifugal heat pump unit 6, a second-stage magnetic levitation centrifugal heat pump unit 7, a third-stage magnetic levitation centrifugal heat pump unit 18, a fourth-stage magnetic levitation centrifugal heat pump unit 19, and a fifth-stage magnetic levitation centrifugal heat pump unit 20. Through heat exchange in the evaporator, it achieves deep cooling of the 48℃ heat source, and the temperature difference utilization rate is increased by more than 25%.

[0053] The third circulation of low-temperature waste hot water (40℃→32℃): The second cooling circulation pipeline 9 directly exchanges heat through the first plate heat exchanger 1, avoiding the entry of low-grade heat sources into the high-energy-consuming heat pump and reducing system power consumption.

[0054] Municipal return water (30℃) passes sequentially through the first plate heat exchanger 1 and the third plate heat exchanger 3 in the second heating circulation pipeline 12, utilizing waste heat for direct heat exchange, thus reducing the load on the magnetic levitation centrifugal heat pump of the second waste heat circulation unit 200. The seven-stage heat pump condensers are connected in series. The magnetic levitation centrifugal heat pump has no mechanical losses, and the temperature rise per stage can reach 8–12℃. The overall COP is ≥6.0, resulting in 30% energy savings compared to traditional heat pumps.

[0055] II. System Integration and Intelligent Control Configure the number of magnetic levitation centrifugal heat pumps as needed, including the first magnetic levitation centrifugal heat pump group 4, the second magnetic levitation centrifugal heat pump group 5, the first-stage magnetic levitation centrifugal heat pump group 6, the second-stage magnetic levitation centrifugal heat pump group 7, the third-stage magnetic levitation centrifugal heat pump group 18, the fourth-stage magnetic levitation centrifugal heat pump group 19, and the fifth-stage magnetic levitation centrifugal heat pump group 20. Match the real-time load through start-stop combinations to avoid inefficient operation.

[0056] The heat exchange channel 32 of the third plate heat exchanger 3 serves as a heat transfer hub, preheating the low-grade heat source (36.8℃) to 45.5℃ before it enters the magnetic levitation centrifugal heat pump condenser, thereby reducing the pressure ratio of the magnetic levitation centrifugal heat pump system.

[0057] III. Operational Stability and Reliability When a single magnetic levitation centrifugal heat pump fails, the remaining units can still maintain partial load operation. Sensors (such as those installed at the inlet and outlet of the evaporator and condenser of each magnetic levitation centrifugal heat pump) are installed. Figure 2 and Figure 3 As shown in the figure, when an end difference is detected, the speed of the circulating pump is automatically adjusted or the corresponding valve is closed; the dirt separator 15 in front of the third circulating pump 16 intercepts particles ≥50μm to avoid clogging the corrugated channel of the plate heat exchanger.

[0058] IV. Economic and Environmental Benefits Compared with traditional electric heating solutions, the system reduces the unit energy consumption of heating municipal water supply from 30℃ to 88.7℃ by 70% (calculated based on COP=6.0), achieves a waste heat recovery rate of ≥85% for industrial wastewater, and reduces cooling tower makeup water by more than 30%. For every 1GJ of waste heat recovered, CO2 emissions from coal-fired boilers can be reduced by approximately 110kg. It also eliminates thermal pollution and avoids the damage to aquatic ecosystems caused by the direct discharge of 50℃ wastewater.

[0059] Example 2 like Figure 4 As shown, the difference from Embodiment 1 is that the heat exchanger group of the second waste heat circulation unit 200 further includes a second plate heat exchanger 2 and a first heating circulation pipeline 11 connected to the second plate heat exchanger 2. The second plate heat exchanger 2 is for ensuring plate heat exchange. The municipal water side of the second plate heat exchanger 2 is connected to the first heating circulation pipeline 11, and the waste water side of the second plate heat exchanger 2 is connected to the first cooling circulation pipeline 8. That is, a second plate heat exchanger 2 is added to the first cooling circulation pipeline 8. The inlet of the first heating circulation pipeline 11 is connected to 32°C cooling water, and its return outlet outputs 40°C return water. While the first cooling circulation pipeline 8, the second cooling circulation pipeline 9, the third cooling circulation pipeline 10, and the second heating circulation pipeline 12 are operating, the first heating circulation pipeline 11 is also operating. Specifically: The 50℃ heat source water enters the third plate heat exchanger 3 via the first circulation pump 13 and is cooled to 42℃. The 42℃ water then enters the magnetic levitation centrifugal heat pump evaporators in the first magnetic levitation centrifugal heat pump group 4 and the second magnetic levitation centrifugal heat pump group 5, where it is cooled to 35℃. The 35℃ water exiting each evaporator merges and enters the second plate heat exchanger 2 to further maintain its 35℃ temperature, and finally returns to the return port of the first cooling circulation pipeline 8. Simultaneously, the 32℃ cooling water enters the second plate heat exchanger 2, where it is heated to 40℃ and returns to the return port of the first heating circulation pipeline 11.

[0060] like Figure 5As shown, the second plate heat exchanger 2 includes heat exchange channel I21 and heat exchange channel II22. The inlet of heat exchange channel I21 is connected to the evaporator outlet of the first magnetic levitation centrifugal heat pump unit 4 and the second magnetic levitation centrifugal heat pump unit 5, and its outlet is connected to the return port of the first cooling circulation pipeline 8. The inlet of heat exchange channel II22 is connected to the inlet of the first heating circulation pipeline 11, and the inlet of heat exchange channel II22 is connected to the return port of the first heating circulation pipeline 11.

[0061] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A waste heat recovery system comprising at least two waste water circuits, characterized in that, It also includes N waste heat circulation units, where N > 2. The N waste heat circulation units include a first waste heat circulation unit, a second waste heat circulation unit, ..., an Nth waste heat circulation unit. The number of waste heat circulation units is consistent with the number of waste water circuits. The first waste heat circulation unit includes at least one heat exchanger group, which includes at least one plate heat exchanger. The Nth waste heat circulation unit includes at least one magnetic levitation centrifugal heat pump group, which includes at least one magnetic levitation centrifugal heat pump, which includes a magnetic levitation variable frequency compressor.

2. The waste heat recovery and utilization system according to claim 1, characterized in that, All waste heat circulation units are independent on the waste water side, and all waste heat circulation units are connected in series on the municipal water side.

3. The waste heat recovery and utilization system according to claim 1, characterized in that, The magnetic levitation centrifugal heat pump unit includes two magnetic levitation centrifugal heat pumps, with the condensers of the two magnetic levitation centrifugal heat pumps connected in parallel and the evaporators of the two magnetic levitation centrifugal heat pumps connected in parallel.

4. The waste heat recovery and utilization system according to claim 2, characterized in that, The first waste heat circulation unit also includes a second cooling circulation pipeline, which is connected to the waste water side of the heat exchanger group of the first waste heat circulation unit.

5. The waste heat recovery and utilization system according to claim 2, characterized in that, The Nth waste heat circulation unit also includes a third cooling circulation pipeline, which is connected to the municipal water side of the magnetic levitation centrifugal heat pump unit in the Nth waste heat circulation unit.

6. The waste heat recovery and utilization system according to claim 2, characterized in that, The waste heat recovery and utilization system also includes a second heating circulation pipeline, which is connected to the municipal water side of the first waste heat circulation unit, ..., the Nth waste heat circulation unit respectively.

7. The waste heat recovery and utilization system according to claim 2, characterized in that, The heat exchanger group of the second waste heat circulation unit includes a third plate heat exchanger, a first magnetic levitation centrifugal heat pump group, and a second magnetic levitation centrifugal heat pump group; the magnetic levitation centrifugal heat pump group of the Nth waste heat circulation unit includes a first-stage magnetic levitation centrifugal heat pump group, a second-stage magnetic levitation centrifugal heat pump group, a third-stage magnetic levitation centrifugal heat pump group, a fourth-stage magnetic levitation centrifugal heat pump group, and a fifth-stage magnetic levitation centrifugal heat pump group.

8. The waste heat recovery and utilization system according to claim 7, characterized in that, The heat exchanger group of the second waste heat circulation unit also includes a second plate heat exchanger and a first heating circulation pipeline connected to the second plate heat exchanger. The second plate heat exchanger is for ensuring plate heat exchange. The municipal water side of the second plate heat exchanger is connected through the first heating circulation pipeline, and the waste water side of the second plate heat exchanger is connected through the first cooling circulation pipeline.

9. The waste heat recovery and utilization system according to claim 8, characterized in that, The heat exchanger group of the first waste heat circulation unit includes a first plate heat exchanger and a second cooling circulation pipeline connected to the first plate heat exchanger. The municipal water side of the first plate heat exchanger is connected through a first heating circulation pipeline, and the waste water side of the first plate heat exchanger is connected through a second cooling circulation pipeline.

10. The waste heat recovery and utilization system according to claim 9, characterized in that, The first cooling circulation pipeline is sequentially connected to the third plate heat exchanger, the first magnetic levitation centrifugal heat pump unit and the second magnetic levitation centrifugal heat pump unit connected in parallel, and the second plate heat exchanger. The second cooling circulation pipeline is connected to the first plate heat exchanger. The third cooling circulation pipeline is sequentially connected to the first-stage magnetic levitation centrifugal heat pump unit and the second-stage magnetic levitation centrifugal heat pump unit. The first heating circulation pipeline is connected to the second plate heat exchanger. The second heating circulation pipeline is sequentially connected to the first plate heat exchanger, the third plate heat exchanger, the first magnetic levitation centrifugal heat pump unit, the second magnetic levitation centrifugal heat pump unit, the fifth-stage magnetic levitation centrifugal heat pump unit, the fourth-stage magnetic levitation centrifugal heat pump unit, the third-stage magnetic levitation centrifugal heat pump unit, the second-stage magnetic levitation centrifugal heat pump unit, and the first-stage magnetic levitation centrifugal heat pump unit.

11. The waste heat recovery and utilization system according to claim 7, characterized in that: The third plate heat exchanger includes a heat exchange channel one and a heat exchange channel two. The inlet of heat exchange channel one is connected to the outlet of the first circulating pump. The outlet of heat exchange channel one is connected to the inlet of the magnetic levitation centrifugal heat pump evaporator in the first magnetic levitation centrifugal heat pump group and the second magnetic levitation centrifugal heat pump group, respectively. The outlet of the evaporator is connected to the second plate heat exchanger.

12. The waste heat recovery system of claim 9, wherein: The first plate heat exchanger includes heat exchange channel A and heat exchange channel B. The inlet of heat exchange channel A is connected to the inlet of the second cooling circulation pipeline, and the outlet of heat exchange channel A is connected to the return port of the second cooling circulation pipeline. The inlet of heat exchange channel B is connected to the outlet of the third circulation pump, and the outlet of heat exchange channel B is connected to the inlet of heat exchange channel two of the third plate heat exchanger. The outlet of heat exchange channel two is sequentially connected to the inlet of the magnetic levitation centrifugal heat pump condenser in the first magnetic levitation centrifugal heat pump group, the second magnetic levitation centrifugal heat pump group, the second-stage magnetic levitation centrifugal heat pump group, and the first-stage magnetic levitation centrifugal heat pump group. The outlet of the condenser is connected to the inlet of the fourth circulation pump.

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