Backwater conduit heat recovery device

Abstract

The application discloses a backwater pipeline heat recovery device, and belongs to the technical field of industrial energy recovery. Through the technical scheme, the backwater pipeline heat recovery device realizes step-by-step heating of raw water by sequentially connecting a first heat exchanger and a second heat exchanger in series in a raw water pipeline and respectively utilizing backwater heat of a refrigeration device and boiler flue gas waste heat as heat sources. The device effectively recovers two different grade waste heat resources in industrial production, and uses the originally possible abandoned or discharged heat energy to increase the temperature of raw water, thereby reducing the external energy consumption required for heating raw water in subsequent processes. Meanwhile, the refrigeration system does not need to consume more energy to recool backwater to the required low temperature, realizes comprehensive utilization of energy, and reduces the operation load and energy consumption of the system.

Description

Technical Field

[0001] This application relates to the field of industrial energy recovery technology, and in particular to a heat recovery device for a return water pipeline. Background Technology

[0002] In industrial production, process refrigeration systems generate high-temperature return water, which typically carries a large amount of unused low-temperature heat energy. Currently, the recovery and utilization of this waste heat from the return water is insufficient, and its heat is often directly wasted. This not only leads to energy waste but also requires the refrigeration system to consume more energy to recool the return water to the required low temperature, increasing the system's operating load and energy consumption. Utility Model Content

[0003] This application provides a heat recovery device for a return water pipeline, which improves the efficiency of waste heat recovery and utilization, thereby at least partially solving the above-mentioned technical problems.

[0004] To achieve the above objectives, according to a first aspect of this application, a heat recovery device for a return water pipeline is provided, comprising: Raw water tank; A raw water pipeline is connected to the raw water tank for transporting raw water; The first heat exchanger and the second heat exchanger are connected in series on the raw water pipeline to heat the raw water flowing through it. The heat absorption port of the first heat exchanger is used to connect to the return water pipeline of the refrigeration equipment to absorb the heat from the return water of the refrigeration equipment. The heat absorption port of the second heat exchanger is used to connect to the boiler flue gas pipeline to absorb the waste heat of the flue gas.

[0005] In some embodiments, it also includes: The first heating pipeline is connected to the heat absorption port of the first heat exchanger and is used to connect the first heat exchanger to the return water pipeline of the refrigeration equipment. The third heat exchanger has its heat absorption port connected to the first heating pipeline to absorb the heat flowing through the first heating pipeline, and its heat release port is connected to the heating equipment.

[0006] In some embodiments, it also includes: A first control valve is disposed between the heat absorption port of the third heat exchanger and the first heating pipeline, and is used to connect or disconnect the passage between the third heat exchanger and the first heating pipeline.

[0007] In some embodiments, it also includes: A first bypass pipeline is connected in parallel to the raw water pipeline, with one end of the first bypass pipeline connected upstream of the first heat exchanger and the other end connected downstream of the second heat exchanger. A first bypass valve is installed on the first bypass pipeline and is used to connect or disconnect the first bypass pipeline.

[0008] In some embodiments, it also includes: The second bypass pipeline is connected in parallel to the raw water pipeline, and one end of the second bypass pipeline is connected to the upstream of the first heat exchanger, and the other end is connected between the downstream of the first heat exchanger and the upstream of the second heat exchanger. The second bypass valve is installed on the second bypass pipeline and is used to connect or disconnect the second bypass pipeline.

[0009] In some embodiments, it also includes: The second control valve is installed on the raw water pipeline and located on the inlet side and / or outlet side of the first heat exchanger, for connecting or disconnecting the raw water passage flowing through the first heat exchanger. When the second control valve is open and the second bypass valve is closed, the raw water flows to the second heat exchanger via the second bypass pipeline.

[0010] In some embodiments, it also includes: A water purification device is connected to the output end of the raw water pipeline to receive heated raw water.

[0011] In some embodiments, it also includes: A temperature monitoring device is installed on the raw water pipeline and located downstream of the second heat exchanger. The temperature monitoring device is used to detect the temperature of the raw water flowing out of the second heat exchanger.

[0012] In some embodiments, it also includes: A fourth heat exchanger is installed on the raw water pipeline and located downstream of the second heat exchanger. The fourth heat exchanger is used to heat the raw water flowing out of the second heat exchanger.

[0013] In some embodiments, a water pump is also included, which is disposed on the raw water pipeline for pressurizing the raw water; And / or, the first heat exchanger is a plate heat exchanger; And / or, the second heat exchanger is a flue gas heat exchanger.

[0014] In the heat recovery device for the return water pipeline of this application embodiment, a first heat exchanger and a second heat exchanger are connected in series in the raw water pipeline, and the heat from the return water of the refrigeration equipment and the waste heat from the boiler flue gas are used as heat sources respectively, thereby realizing the cascade heating of the raw water. This device effectively recovers two different grades of waste heat resources in industrial production, using heat energy that might otherwise be discarded or discharged to raise the temperature of the raw water, thereby reducing the external energy consumption required for heating the raw water in subsequent processes. At the same time, it also eliminates the need for the refrigeration system to consume additional energy to recool the return water to the required low temperature, achieving comprehensive energy utilization while reducing the system's operating load and energy consumption.

[0015] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0017] Figure 1 This is a schematic diagram of the heat recovery device for the return water pipeline provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the heat recovery device for the return water pipeline provided in Embodiment 2 of this application; Figure 3 This is a schematic diagram of the heat recovery device for the return water pipeline provided in Embodiment 3 of this application; Figure 4 This is a schematic diagram of the heat recovery device for the return water pipeline provided in Embodiment 4 of this application; Figure 5 This is a schematic diagram of the heat recovery device for the return water pipeline provided in Embodiment 5 of this application; Figure 6 This is a schematic diagram of the heat recovery device for the return water pipeline provided in Embodiment Six of this application; Figure 7 yes Figure 6 The diagram shows a usage state of the heat recovery device in the return water pipeline.

[0018] Explanation of reference numerals in the attached figures: 100-Raw water tank; 200-Raw water pipeline; 210-Second bypass pipeline; 211-Second bypass valve; 220-Second control valve; 230-Water pump; 240-Temperature monitoring device; 250-Third control valve; 300-First heat exchanger; 310-First heating pipeline; 320-Fourth control valve; 400-Second heat exchanger; 410-Boiler flue gas pipeline; 500-Refrigeration equipment; 510-Return water pipeline; 600-Third heat exchanger; 610-First control valve; 700-Heating equipment; 710-Heat monitoring device; 720-Booster pump; 800-First bypass pipeline; 810-First bypass valve; 900-Fourth heat exchanger; 1000-Water purification equipment. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0020] Embodiment 1 of this application provides a heat recovery device for a return water pipeline, the basic structure of which is described in [reference needed]. Figure 1 The device includes a raw water tank 100, a raw water pipeline 200, a first heat exchanger 300, and a second heat exchanger 400.

[0021] Raw water tank 100 is used to store raw water to be heated. Raw water pipeline 200 is connected to the outlet of raw water tank 100 to transport the raw water to subsequent treatment stages. First heat exchanger 300 and second heat exchanger 400 are connected in series on raw water pipeline 200 to form a two-stage heating structure. Raw water flowing through raw water pipeline 200 will pass through the first heat exchanger 300 and the second heat exchanger 400 successively, and will be heated step by step.

[0022] The heat absorption port of the first heat exchanger 300 is connected to the return water pipe 510 of the refrigeration equipment 500. During operation, the refrigeration equipment 500 generates high-temperature return water, which carries low-temperature heat energy that can be recovered. The first heat exchanger 300 absorbs heat from the return water pipe 510 of the refrigeration equipment 500 through its heat absorption port and transfers this heat to the raw water flowing through it.

[0023] The heat absorption port of the second heat exchanger 400 is used to connect to the boiler flue gas pipeline 410. The flue gas emitted during boiler operation also carries a large amount of waste heat. The second heat exchanger 400 absorbs the waste heat from the flue gas in the boiler flue gas pipeline 410 through its heat absorption port and further heats the raw water that has already undergone the first stage of heating.

[0024] This device, through its aforementioned structure, achieves the tiered recovery and utilization of two types of industrial waste heat—heat from the refrigeration equipment's return water (500℃) and waste heat from boiler flue gas—each of different grades. In a specific application, for example, raw water at approximately 8℃ first enters the first heat exchanger 300, where it is preheated to around 17℃ by the refrigeration return water (approximately 18℃). Subsequently, the preheated raw water enters the second heat exchanger 400, where it is further heated to approximately 23℃ by the boiler flue gas waste heat, meeting the inlet water temperature requirements of subsequent processes (such as pure water preparation). This process, while increasing the raw water temperature, also reduces the refrigeration return water temperature, alleviating the cooling load on the refrigeration system and achieving a dual energy-saving effect.

[0025] Optionally, the first heat exchanger 300 can be a plate heat exchanger. Plate heat exchangers are typically composed of stacked corrugated metal plates, with flow channels formed between the plates. They feature high heat transfer efficiency, compact structure, and small footprint. Since the heat exchange between the return water and the raw water in the refrigeration equipment 500 is a liquid-liquid heat exchange under a moderate temperature difference, the high-efficiency heat transfer characteristics of the plate heat exchanger can fully recover the low-temperature heat in the return water. Furthermore, its compact structure facilitates integration and installation within existing piping systems. In specific applications, the first heat exchanger 300 can employ a 1℃ differential water-plate heat exchanger.

[0026] Optionally, the second heat exchanger 400 can be a flue gas heat exchanger. It can adapt to the harsh operating conditions of boiler flue gas, safely and reliably recover medium-temperature waste heat from the flue gas, thereby effectively reducing the exhaust gas temperature and improving the overall energy utilization rate.

[0027] By matching different types of dedicated heat exchangers to the two heat sources of different grades, low-temperature return water and medium-temperature flue gas, this device can optimize the efficiency of each heat exchange link while ensuring the reliability and durability of the system, thereby improving the overall performance of the entire heat recovery system.

[0028] Optionally, a water pump 230 is installed on the raw water pipeline 200. This water pump 230 is used to pressurize the raw water output from the raw water tank 100, ensuring that the raw water can flow with sufficient velocity and pressure through the first heat exchanger 300, the second heat exchanger 400, and any other possible subsequent heat exchange equipment, overcoming the flow resistance of the entire pipeline system and ensuring heat exchange efficiency and water flow stability. Specifically, the water pump 230 can be located between the outlet of the raw water tank 100 and the inlet of the first heat exchanger 300. At this location, the water pump 230 is responsible for pressurizing the raw water in the entire system, ensuring that the water flow can successively overcome the flow resistance of the first heat exchanger 300, the second heat exchanger 400, and their connecting pipelines, maintaining a stable flow rate and heat exchange effect.

[0029] Example 2 differs from Example 1 in that it adds a heat distribution structure to enable more ways to utilize the waste heat from the return water pipe. The device configuration of this example can be found in [reference needed]. Figure 2 .

[0030] like Figure 2 As shown, the heat recovery device for the return water pipe in this embodiment further includes a first heating pipe 310 and a third heat exchanger 600. The first heating pipe 310 connects the heat absorption port of the first heat exchanger 300 to the return water pipe 510 of the refrigeration equipment 500, forming a heat transfer channel from the return water pipe 510 to the first heat exchanger 300. The heat absorption port of the third heat exchanger 600 is connected to the first heating pipe 310. Thus, the hot fluid flowing through the first heating pipe 310, carrying the heat from the refrigerated return water, can partially or completely flow through the third heat exchanger 600, enabling the third heat exchanger 600 to absorb heat from the hot fluid. The heat release port of the third heat exchanger 600 is used to connect to an external heating device 700, thereby supplying the absorbed heat to the heating system for heating or other purposes.

[0031] With the above structure, the device in this embodiment can not only use the heat from the cooling return water to heat the raw water, but also divert a portion of the return water heat to the heating system, realizing multiple ways to utilize the waste heat from the cooling return water and significantly improving the overall energy utilization efficiency. In actual operation, the ratio used for raw water heating and heating can be flexibly adjusted according to seasonal and demand changes.

[0032] Optionally, the third heat exchanger 600 can be a water source heat pump, preferably a magnetic levitation water source heat pump. The evaporator side (i.e., the heat absorption port) of this heat pump is connected to the first heating pipe 310 as its low-temperature heat source; its condenser side (i.e., the heat release port) is connected to the heating equipment 700 as its high-temperature heat source. The use of a magnetic levitation water source heat pump allows the system to stably provide the required heating heat even when the cooling return water temperature is low, greatly enhancing the system's adaptability and heat output quality under different operating conditions.

[0033] Optionally, a heat monitoring device 710 and a booster pump 720 can be installed on the connection pipe between the condenser side of the magnetic levitation water source heat pump and the heating equipment 700. The heat monitoring device 710 is used to monitor the temperature and flow rate of the heat medium supplied to the heating equipment 700 in real time. The booster pump 720 is used to ensure that the heated heat medium can be effectively delivered to the heating terminal and overcome the system pipeline resistance.

[0034] Please refer to it again. Figure 2In this embodiment, a first control valve 610 is provided between the heat absorption port of the third heat exchanger 600 and the first heating pipeline 310. This first control valve 610 is used to connect or disconnect the hot fluid passage flowing through the third heat exchanger 600. Different operating modes can be achieved by operating the first control valve 610. When it is necessary to simultaneously heat the raw water and supply heat to the heating equipment 700, the first control valve 610 is in the open state, and the hot fluid from the return water pipeline 510 of the refrigeration equipment 500 will flow simultaneously through the first heat exchanger 300 and the third heat exchanger 600. When it is only necessary to heat the raw water and not to supply heat to the heating equipment 700, the first control valve 610 can be closed, thereby cutting off the hot fluid passage to the third heat exchanger 600. At this time, all the heat from the return water will be concentrated on heating the raw water through the first heat exchanger 300.

[0035] The first control valve 610 allows the system to flexibly allocate the heat from the cooling return water according to actual needs, effectively avoiding energy idleness and waste. The first control valve 610 can be a manual valve, or an electric valve, solenoid valve, etc., to achieve automatic control. In specific applications, the heat absorption port of the third heat exchanger 600 has an inlet port and an outlet port. The inlet port is connected to the inlet pipe of the first heating pipe 310 (connected to the output end of the return water pipe 510) through the second heating pipe, and the outlet port is connected to the outlet pipe of the first heating pipe 310 (connected to the input end of the return water pipe 510) through the second heating pipe. The first control valve 610 can be installed at either the inlet port or the outlet port, or both the inlet port and the outlet port can be equipped with the first control valve 610.

[0036] In some embodiments, a fourth control valve 320 is provided on the first heating pipeline 310 at the heat absorption port of the first heat exchanger 300. This fourth control valve 320 is used to control the connection or disconnection of the hot fluid passage between the first heat exchanger 300 and the return water pipeline 510 of the refrigeration equipment 500. By operating the fourth control valve 320, at least one of the following control modes can be achieved: When the fourth control valve 320 is open, the first heat exchanger 300 operates normally, using the heat from the return water to heat the raw water. When the fourth control valve 320 is closed, regardless of the state of the passage of the third heat exchanger 600, the hot fluid flowing to the first heat exchanger 300 is cut off, and the first heat exchanger 300 stops heat recovery.

[0037] For example, if the cooling return water temperature is too low, insufficient to effectively heat the raw water, or may cause scaling in the first heat exchanger 300, the first heat exchanger 300 can be shut down independently. The fourth control valve 320, in conjunction with the first control valve 610, enables flexible switching between multiple heating modes: it can heat only the raw water, it can be used only for heating, it can heat both raw water and heating simultaneously, or neither can be used. This improves the system's adaptability to different operating conditions and enhances operational flexibility. The fourth control valve 320 can also be selected for manual or automatic control.

[0038] like Figure 3 As shown, in Embodiment 3, the heat recovery device for the return water pipeline has a first bypass pipeline 800 connected in parallel to the raw water pipeline 200. One end of the first bypass pipeline 800 is connected upstream of the first heat exchanger 300, and the other end is connected downstream of the second heat exchanger 400. A first bypass valve 810 is also provided on the first bypass pipeline 800 to control the opening and closing of the pipeline. When the first bypass valve 810 is open, the raw water can bypass the first heat exchanger 300 and the second heat exchanger 400 directly via the first bypass pipeline 800 and be delivered to the downstream equipment.

[0039] Therefore, the heat recovery device for the return water pipeline in this embodiment has at least two operating modes: a heat recovery mode in which the first bypass valve 810 is closed and the raw water flows sequentially through the first heat exchanger 300 and the second heat exchanger 400 to be heated; and a direct-flow mode in which the first bypass valve 810 is open and the raw water is directly transported downstream without being heated.

[0040] When any or all of the first heat exchanger 300 and the second heat exchanger 400 require maintenance or cleaning, or during special phases such as system startup and commissioning, the installation of this first bypass pipeline 800 and valves improves the operational flexibility and reliability of the entire system.

[0041] In this embodiment, a water pump 230 is also installed in the raw water pipeline 200. One option is to position the water pump 230 upstream of the first heat exchanger 300 and the first bypass pipeline 800. In this case, the water pump 230 can provide power to the entire system regardless of whether the device operates in heat recovery mode or direct flow mode. Another feasible option is to position the water pump 230 downstream of the junction of the first bypass pipeline 800 and the main raw water pipeline 200. This arrangement ensures that in direct flow mode, the water flow will not experience unnecessary pressure drops due to passing through a non-operating heat exchanger, potentially helping to reduce the energy consumption of the water pump 230. Alternatively, separate water pumps 230 can be provided for heat recovery mode and direct flow mode respectively.

[0042] like Figure 4As shown, in Embodiment 4, the heat recovery device for the return water pipeline has a second bypass pipeline 210 connected in parallel to the raw water pipeline 200. One end of the second bypass pipeline 210 is connected upstream of the first heat exchanger 300, and the other end is connected between the downstream of the first heat exchanger 300 and the upstream of the second heat exchanger 400. A second bypass valve 211 is also provided on the second bypass pipeline 210 to control the opening and closing of the bypass path. When the second bypass valve 211 is open, the raw water can flow directly to the inlet of the second heat exchanger 400 via the second bypass pipeline 210, bypassing the first heat exchanger 300.

[0043] Therefore, the heat recovery device for the return water pipeline in this embodiment can handle different operating conditions: When the second bypass valve 211 is closed, the raw water flows sequentially through the first heat exchanger 300 and the second heat exchanger 400 for two-stage heating. This mode is suitable for operating conditions requiring a maximum increase in the raw water temperature. When the second bypass valve 211 is open, the raw water bypasses the first heat exchanger 300, and is only heated in one stage by the second heat exchanger 400 using waste heat from the flue gas. This mode is suitable when the refrigeration return water temperature is close to the raw water temperature, the heat exchange driving force is insufficient, or the refrigeration system is not running and cannot provide a heat source for the return water.

[0044] By setting up a second bypass pipe 210 and valves, the operating mode can be switched according to the heat source status and raw water heating requirements in practical applications. Under the premise of ensuring process requirements, ineffective or inefficient heat exchange processes can be avoided, thereby optimizing system energy efficiency.

[0045] Please see again Figure 4 In some embodiments, a second control valve 220 is also provided on the raw water pipeline 200. This second control valve 220 is specifically located on at least one of the inlet and outlet sides of the first heat exchanger 300, and is used to directly connect or disconnect the raw water passage flowing through the first heat exchanger 300. By providing this second control valve 220, it can work in conjunction with the second bypass valve 211, thereby achieving stable switching of the flow path. When the first heat exchanger 300 needs to be activated, the second control valve 220 is placed in the open state, while the second bypass valve 211 is placed in the closed state. At this time, the raw water will flow through the first heat exchanger 300 to absorb heat from the return water. When it is necessary to bypass the first heat exchanger 300, the second control valve 220 is closed to completely cut off the water flow to the first heat exchanger 300, and then the second bypass valve 211 is opened. In this state, that is, when the second control valve 220 is off and the second bypass valve 211 is on, the raw water will flow completely through the second bypass pipe 210 to the second heat exchanger 400.

[0046] Both the second control valve 220 and the second bypass valve 211 can be driven manually or automatically as needed.

[0047] Optionally, a third control valve 250 is provided on the raw water pipeline 200 on the inlet and outlet sides of the second heat exchanger 400, respectively. By simultaneously closing the third control valve 250 on the inlet and outlet sides, the raw water passages entering and flowing out of the second heat exchanger 400 can be completely disconnected, thereby achieving complete isolation between the second heat exchanger 400 and the raw water pipeline 200.

[0048] like Figure 5 As shown, in Embodiment 5, the heat recovery device for the return water pipeline is connected to a water purification device 1000 at the output end of the raw water pipeline 200. The raw water, heated to the target temperature by the first heat exchanger 300 and the second heat exchanger 400, is transported to the water purification device 1000 as its inlet water.

[0049] Optionally, the water treatment equipment 1000 may specifically be a pure water preparation device, a water softening treatment device, or other water treatment device that requires preheating of the incoming water. Supplying raw water preheated by a waste heat recovery system to such equipment can significantly reduce its heating energy consumption. For example, in one specific embodiment, preheating the raw water to approximately 23°C before sending it to the pure water preparation equipment can effectively reduce the operating energy consumption of the pure water preparation unit.

[0050] like Figure 6 As shown, the heat recovery device for the return water pipeline in Embodiment Six also includes a temperature monitoring element 240. Specifically, a temperature monitoring element 240 is installed on its raw water pipeline 200, downstream of the second heat exchanger 400. This temperature monitoring element 240 is used to detect the temperature of the raw water flowing out of the second heat exchanger 400 in real time. The temperature signal acquired by the temperature monitoring element 240 can be used as a basis for judging the system's operating status. When the detected water temperature is consistently lower than the process requirements, an alarm can be issued to prompt the operator to check the heat source status or the performance of the heat exchanger. Furthermore, this temperature signal can be used as an input to the control logic. For example, if the water temperature is lower than the set value, the fourth heat exchanger 900, which may be installed downstream, can be linked to perform supplementary heating; or, in a system equipped with a fourth control valve 320, if the outlet water temperature of the first heat exchanger 300 is already too high, the fourth control valve 320 can be appropriately closed to reduce heat recovery and prevent the raw water temperature from exceeding the requirements.

[0051] Optionally, a fourth heat exchanger 900 can be added to the raw water pipeline 200, downstream of the second heat exchanger 400. This fourth heat exchanger 900 is used to supplement the heating of the raw water flowing out of the second heat exchanger 400. If the raw water temperature still fails to reach the process target value after two stages of heating by only the first heat exchanger 300 and the second heat exchanger 400, the system is activated to perform a final temperature adjustment on the raw water, ensuring it reaches the required temperature precisely before entering the water treatment equipment 1000.

[0052] The heat source for the fourth heat exchanger 900 can be steam or high-temperature hot water generated by a boiler, or it can be electric heating or other available heat sources depending on site conditions. In a specific application, the fourth heat exchanger 900 can be a water-to-water plate heat exchanger.

[0053] like Figure 7 As shown, in a specific application example, raw water at a temperature of approximately 8°C is output from the raw water tank 100 and first enters the first heat exchanger 300 via the raw water pipeline 200. Inside the first heat exchanger 300, the raw water exchanges heat with return water at a temperature of approximately 18°C ​​in the return water pipeline 510 from the refrigeration equipment 500. Through this heat exchange process, the raw water is preheated to approximately 17°C, while the refrigeration return water temperature is correspondingly reduced to approximately 12.5°C, meeting the refrigeration system's requirements for the return water temperature.

[0054] Subsequently, the preheated raw water (approximately 17°C) enters the second heat exchanger 400. Inside the second heat exchanger 400, the raw water exchanges heat with the flue gas emitted from the boiler, absorbing the waste heat from the flue gas, and its temperature is further increased to approximately 23°C. At this point, if the temperature monitoring device 240 located downstream of the second heat exchanger 400 detects that the raw water temperature has reached the target value of 23°C, then the subsequent fourth heat exchanger 900 will not need to be started.

[0055] However, in actual operation, if the temperature of the raw water heated by the second heat exchanger 400 fails to reach 23°C (for example, only 21°C) due to boiler load fluctuations or changes in flue gas parameters, the temperature monitoring device 240 will detect this signal. Based on this signal, the system control unit can control the fourth heat exchanger 900 to start and perform supplementary heating to ensure that the temperature of the raw water finally entering the water treatment equipment 1000 is stable at the required 23°C.

[0056] In an application scenario where a third heat exchanger 600 is installed, the return water from the return water pipe 510 of the refrigeration equipment 500 enters the first heating pipe 310 and, as a common heat source, is distributed to two parallel heat exchange units: the first heat exchanger 300 and the third heat exchanger 600.

[0057] Part of the return water flowing through the heat absorption port of the third heat exchanger 600 releases heat within the third heat exchanger 600, and its temperature drops from approximately 18°C ​​to approximately 12.5°C. Subsequently, this cooled return water merges with the return water flowing out of the first heat exchanger 300, which has also cooled to approximately 12.5°C, and returns to the refrigeration system or enters subsequent cooling equipment.

[0058] Meanwhile, the heating return water from the heating system 700, with a temperature assumed to be 36°C, flows into the heat release port of the third heat exchanger 600. This heating return water absorbs heat extracted from the cooling return water within the third heat exchanger 600, thus increasing its temperature, for example, from 36°C to 45°C. The heated heating supply water is then returned to the heating system 700 to meet heating demands.

[0059] It should be noted that in the accompanying drawings corresponding to the embodiments of this application, hollow arrows are used to indicate the direction of water flow. Specifically, the hollow arrow in the raw water pipe 200 indicates the direction of raw water flow; the hollow arrow at the return water pipe 510 indicates the direction of refrigeration return water flow in the refrigeration equipment 500; and the hollow arrow between the third heat exchanger 600 and the heating equipment 700 indicates the direction of heating return water flow.

[0060] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0061] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0062] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0063] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A heat recovery device for a return water pipeline, characterized in that, include: Raw water tank; A raw water pipeline is connected to the raw water tank for transporting raw water; The first heat exchanger and the second heat exchanger are connected in series on the raw water pipeline to heat the raw water flowing through it. The heat absorption port of the first heat exchanger is used to connect to the return water pipeline of the refrigeration equipment to absorb the heat from the return water of the refrigeration equipment. The heat absorption port of the second heat exchanger is used to connect to the boiler flue gas pipeline to absorb the waste heat of the flue gas.

2. The heat recovery device for return water pipeline according to claim 1, characterized in that, Also includes: The first heating pipeline is connected to the heat absorption port of the first heat exchanger and is used to connect the first heat exchanger to the return water pipeline of the refrigeration equipment. The third heat exchanger has its heat absorption port connected to the first heating pipeline to absorb the heat flowing through the first heating pipeline, and its heat release port is connected to the heating equipment.

3. The heat recovery device for the return water pipeline according to claim 2, characterized in that, Also includes: A first control valve is disposed between the heat absorption port of the third heat exchanger and the first heating pipeline, and is used to connect or disconnect the passage between the third heat exchanger and the first heating pipeline.

4. The heat recovery device for return water pipeline according to claim 1, characterized in that, Also includes: A first bypass pipeline is connected in parallel to the raw water pipeline, with one end of the first bypass pipeline connected upstream of the first heat exchanger and the other end connected downstream of the second heat exchanger. A first bypass valve is installed on the first bypass pipeline and is used to connect or disconnect the first bypass pipeline.

5. The heat recovery device for return water pipeline according to claim 1, characterized in that, Also includes: The second bypass pipeline is connected in parallel to the raw water pipeline, and one end of the second bypass pipeline is connected to the upstream of the first heat exchanger, and the other end is connected between the downstream of the first heat exchanger and the upstream of the second heat exchanger. The second bypass valve is installed on the second bypass pipeline and is used to connect or disconnect the second bypass pipeline.

6. The heat recovery device for the return water pipeline according to claim 5, characterized in that, Also includes: The second control valve is installed on the raw water pipeline and located on the inlet side and / or outlet side of the first heat exchanger, for connecting or disconnecting the raw water passage flowing through the first heat exchanger. When the second control valve is open and the second bypass valve is closed, the raw water flows to the second heat exchanger through the second bypass pipeline.

7. The heat recovery device for return water pipeline according to claim 1, characterized in that, Also includes: A water purification device is connected to the output end of the raw water pipeline to receive heated raw water.

8. The heat recovery device for the return water pipeline according to claim 7, characterized in that, Also includes: A temperature monitoring device is installed on the raw water pipeline and located downstream of the second heat exchanger. The temperature monitoring device is used to detect the temperature of the raw water flowing out of the second heat exchanger.

9. The heat recovery device for the return water pipeline according to claim 7 or 8, characterized in that, Also includes: A fourth heat exchanger is installed on the raw water pipeline and located downstream of the second heat exchanger. The fourth heat exchanger is used to heat the raw water flowing out of the second heat exchanger.

10. The heat recovery device for the return water pipeline according to claim 1, characterized in that, It also includes a water pump, which is installed on the raw water pipeline to pressurize the raw water; And / or, the first heat exchanger is a plate heat exchanger; And / or, the second heat exchanger is a flue gas heat exchanger.

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