Waste heat recovery system for papermaking process

Abstract

The utility model discloses a papermaking process waste heat recovery system which comprises a direct contact type heat exchanger, a heat exchanger spraying device is arranged in the direct contact type heat exchanger, and the direct contact type heat exchanger is provided with a heat exchanger air inlet, a heat exchanger air outlet, a heat exchanger water inlet and a heat exchanger water outlet. The heat exchanger air inlet is suitable for introducing wet and hot air generated by a papermaking process, and the heat exchanger water inlet is communicated with the heat exchanger spraying device; and the waste heat recovery device communicates with the heat exchanger water inlet and the heat exchanger water outlet and is suitable for recovering waste heat in hot water discharged from the heat exchanger water outlet. The waste heat recovery system for the papermaking process has the advantages of being sufficient and thorough in waste heat recovery, capable of avoiding corrosion of the heat exchanger, low in maintenance cost, small in emission pollution and the like.

Description

Technical Field

[0001] This utility model relates to the field of papermaking technology, and more specifically, to a waste heat recovery system for papermaking processes. Background Technology

[0002] Paper mills generate a significant amount of waste heat during the papermaking and drying process. This waste heat primarily originates from the paper drying process itself, which utilizes hot air to dry the paper. During the drying process, the hot air removes moisture from the paper's surface, creating humid, hot air.

[0003] The temperature of the humid air discharged during the paper drying process is 70-80℃. To effectively utilize this waste heat, paper mills employ waste heat recovery systems. The waste heat generated during the drying process is collected and reused in other stages of paper production.

[0004] The waste heat recovery system in the papermaking process in related technologies uses a partitioned heat exchanger, which has low heat exchange efficiency and poor cooling and dehumidification effect on the hot and humid air generated during the drying process. In addition, the exhaust gas from the papermaking dryer contains organic components from the papermaking materials, which can contaminate the surface of the heat exchanger, reduce its heat transfer efficiency, and in severe cases, cause corrosion to the surface of the heat exchanger, leading to increased operating and maintenance costs. Utility Model Content

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a waste heat recovery system for papermaking processes, which has advantages such as thorough waste heat recovery, avoidance of heat exchanger corrosion, low maintenance costs, and low emissions.

[0006] To achieve the above objectives, an embodiment of this utility model proposes a waste heat recovery system for papermaking processes. The waste heat recovery system includes: a direct-contact heat exchanger, which is equipped with a heat exchanger spray device. The direct-contact heat exchanger has an air inlet, an exhaust outlet, a water inlet, and a water outlet. The air inlet is suitable for introducing humid and hot air generated during the papermaking process, and the water inlet is connected to the water spray device; and a waste heat recovery device, which is connected to both the water inlet and the water outlet and is suitable for recovering waste heat from the hot water discharged from the water outlet.

[0007] The waste heat recovery system for papermaking process according to the present invention has the advantages of thorough waste heat recovery, avoiding heat exchanger corrosion, low maintenance cost, and low emission pollution.

[0008] In addition, the waste heat recovery system for papermaking process according to the above embodiments of this utility model may also have the following additional technical features:

[0009] According to one embodiment of the present invention, the waste heat recovery device includes a heat pump device, which has a first flow channel and a second flow channel. The first flow channel and the second flow channel are adapted to exchange heat within the heat pump device. The heat pump device is provided with a first heat pump inlet, a first heat pump outlet, a second heat pump inlet, and a second heat pump outlet. The two ends of the first flow channel are respectively connected to the first heat pump inlet and the first heat pump outlet, and the two ends of the second flow channel are respectively connected to the second heat pump inlet and the second heat pump outlet. The first heat pump inlet is connected to the outlet of the heat exchanger, the first heat pump outlet is connected to the inlet of the heat exchanger, and the second heat pump inlet and the second heat pump outlet are connected to the heat-using equipment.

[0010] According to one embodiment of the present invention, a hot water pipe is connected between the first heat pump inlet and the heat exchanger outlet, and a cold water pipe is connected between the first heat pump outlet and the heat exchanger inlet.

[0011] According to one embodiment of the present invention, the waste heat recovery device includes: a heat pump device having a first flow channel and a second flow channel, the first flow channel and the second flow channel being adapted for heat exchange within the heat pump device; the heat pump device having a first heat pump inlet, a first heat pump outlet, a second heat pump inlet and a second heat pump outlet; the two ends of the first flow channel being connected to the first heat pump inlet and the first heat pump outlet respectively; the two ends of the second flow channel being connected to the second heat pump inlet and the second heat pump outlet respectively; the second heat pump inlet and the second heat pump outlet being connected to a heat-using device; and a closed-loop steam generator having a generator inlet, a generator outlet and a steam outlet; the closed-loop steam generator having a flash spray device; the generator inlet being connected to the flash spray device; the generator inlet being connected to the heat exchanger outlet; the generator outlet being connected to the heat exchanger inlet; the steam outlet being connected to the first heat pump inlet; and the first heat pump outlet being adapted to discharge condensate.

[0012] According to one embodiment of the present invention, a generator water storage tank is formed at the bottom of the closed steam generator, the flash spray device is arranged above the generator water storage tank, and the generator outlet is connected to the generator water storage tank.

[0013] According to one embodiment of the present invention, a hot water pipe is connected between the heat exchanger outlet and the generator inlet, a cold water pipe is connected between the heat exchanger inlet and the generator outlet, and a steam pipe is connected between the steam outlet and the first heat pump inlet.

[0014] According to one embodiment of the present invention, the second heat pump inlet is adapted to allow softened water to pass through, and the second heat pump outlet is adapted to discharge water or steam.

[0015] According to one embodiment of the present invention, a heat exchanger water tank is formed at the bottom of the direct-contact heat exchanger, the heat exchanger spray device is disposed above the heat exchanger water tank, and the heat exchanger air inlet is located between the heat exchanger spray device and the heat exchanger water tank in the vertical direction.

[0016] According to one embodiment of the present invention, both the hot water pipe and the cold water pipe are connected to on / off valves and fluid state detection devices, and at least one of the hot water pipe and the cold water pipe is connected to a water pump.

[0017] According to one embodiment of the present invention, the heat exchanger exhaust port is connected to the atmosphere.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0020] Figure 1 This is a schematic diagram of the structure of a waste heat recovery system for papermaking process according to a specific embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the waste heat recovery system for papermaking process according to another specific embodiment of the present invention.

[0022] Figure reference numerals: 1. Waste heat recovery system for papermaking process; 10. Direct contact heat exchanger; 11. Heat exchanger spray device; 12. Heat exchanger air inlet; 13. Heat exchanger exhaust port; 14. Heat exchanger water inlet; 15. Heat exchanger water outlet; 16. Heat exchanger water storage tank; 20. Heat pump equipment; 21. First flow channel; 22. Second flow channel; 23. First heat pump inlet; 24. First heat pump outlet; 25. Second heat pump inlet; 26. Second heat pump outlet; 30. Closed-loop steam generator; 31. Flash spray device; 32. Generator water inlet; 33. Generator water outlet; 34. Steam outlet; 35. Generator water storage tank; 41. Hot water pipe; 42. Cold water pipe; 43. Steam pipe. Detailed Implementation

[0023] This application is based on the inventor's discoveries and understanding of the following facts and problems:

[0024] The waste heat recovery system for the papermaking process in related technologies uses a partitioned heat exchanger. The exhaust gas from the papermaking dryer contains organic components from the papermaking materials, which can contaminate the surface of the heat exchanger, reduce its heat transfer efficiency, and in severe cases, cause corrosion to the surface of the heat exchanger, leading to increased operating and maintenance costs.

[0025] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0026] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] The waste heat recovery system 1 for papermaking process according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0029] like Figure 1 and Figure 2 As shown, the waste heat recovery system 1 for papermaking process according to an embodiment of the present invention includes a direct-contact heat exchanger 10 and a waste heat recovery device.

[0030] The direct-contact heat exchanger 10 is equipped with a heat exchanger spray device 11. The direct-contact heat exchanger 10 has a heat exchanger air inlet 12, a heat exchanger exhaust port 13, a heat exchanger water inlet 14, and a heat exchanger water outlet 15. The heat exchanger air inlet 12 is suitable for introducing humid and hot air generated during the papermaking process. The heat exchanger water inlet 14 is connected to the heat exchanger spray device 11. The waste heat recovery device is connected to both the heat exchanger water inlet 14 and the heat exchanger water outlet 15 and is suitable for recovering waste heat from the hot water discharged from the heat exchanger water outlet 15.

[0031] Specifically, the hot and humid air generated by the paper drying process enters the direct-contact heat exchanger 10 through the heat exchanger inlet 12. The heat exchanger spray device 11 sprays the hot and humid air into the direct-contact heat exchanger 10. The spray water directly contacts the hot and humid air for heat exchange. After the temperature and humidity of the air decrease, it is discharged through the heat exchanger exhaust port 13. After the temperature of the spray water increases, it is discharged through the heat exchanger outlet 15. The hot water enters the waste heat recovery device to recover waste heat and cools down before entering the heat exchanger spray device 11 through the heat exchanger inlet 14 to supply spray water.

[0032] According to the waste heat recovery system 1 for papermaking process of this utility model embodiment, a direct-contact heat exchanger 10 is set up, and the heat exchanger spray device 11 of the direct-contact heat exchanger 10 directly sprays the hot and humid air generated by the papermaking process, so that the spray water directly contacts the hot and humid air for heat exchange, thereby cooling and dehumidifying the hot and humid air and generating hot water for recycling by the waste heat recovery device. Compared with the waste heat recovery system for papermaking process using indirect heat exchangers in related technologies, since the spray water and the hot and humid air generated by the papermaking process are in direct contact, it can not only improve the heat exchange efficiency and heat exchange effect, but also more effectively recover waste heat, making the waste heat recovery more complete and thorough. It can reduce the temperature of high temperature and high humidity air to below 30°C, which is far lower than the waste heat recovery level of above 40°C in related technologies. Moreover, it can absorb moisture in the air and reduce the air humidity.

[0033] Furthermore, in the related technology, the waste heat recovery system for the papermaking process uses a partitioned heat exchanger. The exhaust gas from the papermaking dryer contains organic components from the papermaking materials, which can contaminate the surface of the heat exchanger, reducing its heat transfer efficiency and, in severe cases, causing corrosion of the heat exchanger surface, leading to increased operating and maintenance costs. The waste heat recovery system 1 for the papermaking process uses a heat exchanger spray device 11 to spray humid and hot air, which can prevent the organic components of the papermaking materials in the humid and hot air from contaminating the heat exchanger surface, thus avoiding affecting the heat transfer efficiency of the heat exchanger, preventing corrosion of the heat exchanger surface, and reducing the maintenance costs of the direct-contact heat exchanger 10.

[0034] In addition, by directly spraying the hot and humid air generated by the papermaking process, the air can be purified and washed, reducing the concentration of pollutants in the air discharged from the heat exchanger exhaust port 13, facilitating air discharge and reducing pollution emissions.

[0035] Therefore, the waste heat recovery system 1 for papermaking process according to the embodiment of this utility model has the advantages of thorough waste heat recovery, avoiding heat exchanger corrosion, low maintenance cost, and low emission pollution.

[0036] The waste heat recovery system 1 for papermaking process according to a specific embodiment of the present invention is described below with reference to the accompanying drawings.

[0037] In some specific embodiments of this utility model, such as Figure 1 and Figure 2 As shown, the waste heat recovery system 1 for papermaking process according to an embodiment of the present invention includes a direct-contact heat exchanger 10 and a waste heat recovery device.

[0038] In some embodiments, such as Figure 1 As shown, the waste heat recovery device includes a heat pump device 20, which has a first flow channel 21 and a second flow channel 22. The first flow channel 21 and the second flow channel 22 are adapted to exchange heat within the heat pump device 20. The heat pump device 20 is provided with a first heat pump inlet 23, a first heat pump outlet 24, a second heat pump inlet 25, and a second heat pump outlet 26. The two ends of the first flow channel 21 are respectively connected to the first heat pump inlet 23 and the first heat pump outlet 24. The two ends of the second flow channel 22 are respectively connected to the second heat pump inlet 25 and the second heat pump outlet 26. The first heat pump inlet 23 is connected to the heat exchanger outlet 15, the first heat pump outlet 24 is connected to the heat exchanger inlet 14, and the second heat pump inlet 25 and the second heat pump outlet 26 are connected to the heat-using equipment. Hot water discharged from heat exchanger outlet 15 enters heat pump device 20 through first heat pump inlet 23. It exchanges heat with water in second flow channel 22 within first flow channel 21, and after cooling, flows back to heat exchanger spray device 11 via first heat pump outlet 24 and heat exchanger inlet 14 as spray water. Cold water entering second flow channel 22 through second heat pump inlet 25 exchanges heat with water in first and second flow channels 21, and after its temperature rises, it is discharged through second heat pump outlet 26 to heat-using equipment, thus achieving heat recovery and utilization. Therefore, heat pump device 20 can be used to exchange heat with water in first and second flow channels 21 and 22, and the waste heat in the hot water discharged from heat exchanger outlet 15 can be recovered for use in other heat-using equipment.

[0039] Specifically, the heat-using equipment can be used to preheat hot air for drying, preheat cold outdoor air for heating, and heat water for washing.

[0040] Specifically, such as Figure 1As shown, a hot water pipe 41 connects the first heat pump inlet 23 to the heat exchanger outlet 15, and a cold water pipe 42 connects the first heat pump outlet 24 to the heat exchanger inlet 14. This facilitates the connection of the direct-contact heat exchanger 10 with the heat pump equipment 20, and facilitates the guidance of cold and hot water.

[0041] In other embodiments, such as Figure 2 As shown, the waste heat recovery device includes a heat pump unit 20 and a closed-loop steam generator 30. The heat pump unit 20 has a first flow channel 21 and a second flow channel 22, which are adapted for heat exchange within the heat pump unit 20. The heat pump unit 20 is provided with a first heat pump inlet 23, a first heat pump outlet 24, a second heat pump inlet 25, and a second heat pump outlet 26. The two ends of the first flow channel 21 are respectively connected to the first heat pump inlet 23 and the first heat pump outlet 24, and the two ends of the second flow channel 22 are respectively connected to the second heat pump inlet 25 and the second heat pump outlet 26. The second heat pump inlet 25 and the second heat pump outlet 26 are connected to the heat-using equipment. The closed-loop steam generator 30 is equipped with a generator inlet 32, a generator outlet 33, and a steam outlet 34. A flash spray device 31 is installed inside the closed-loop steam generator 30. The generator inlet 32 ​​is connected to the flash spray device 31, and the generator inlet 32 ​​is connected to the heat exchanger outlet 15. The generator outlet 33 is connected to the heat exchanger inlet 14, and the steam outlet 34 is connected to the first heat pump inlet 23. The first heat pump outlet 24 is suitable for discharging condensate. Specifically, the hot water discharged from the heat exchanger outlet 15 enters the flash spray device 31 through the generator inlet 32 ​​for spraying, causing flash evaporation to occur inside the closed-loop steam generator 30 to generate low-temperature, low-pressure steam. After the water temperature decreases, it is discharged through the generator outlet 33 and flows to the heat exchanger spray device 11 at the heat exchanger inlet 14 as spray water for the direct-contact heat exchanger 10. Steam generated by the closed-loop steam generator 30 is discharged through steam outlet 34 and enters the heat pump device 20 through the first heat pump inlet 23. It exchanges heat with water in the second flow channel 22 within the first flow channel 21. After condensation and heat release, the steam is discharged as condensate through the first heat pump outlet 24. Cold water enters the second flow channel 22 through the second heat pump inlet 25. After heat exchange in the first and second flow channels 21 and 22, the steam in the first flow channel 21 condenses and releases heat, heating the water in the second flow channel 22. The water then exits through the second heat pump outlet 26 after its temperature rises, flowing to the heat-using equipment, thus achieving heat recovery and utilization. In this way, hot water generated by the direct-contact heat exchanger 10 can be used to generate steam in the closed-loop steam generator 30. The steam then condenses and releases heat in the heat pump device 20, heating the water in the second flow channel 22, thereby recovering the waste heat from the hot water discharged from the heat exchanger outlet 15 for use in other heat-using equipment.

[0042] Specifically, the condensate discharged from the first heat pump outlet 24 can be used as makeup water for the papermaking process, or as makeup water for the waste heat recovery system 1 of the papermaking process.

[0043] Advantageously, such as Figure 2 As shown, a generator water storage tank 35 is formed at the bottom of the closed-loop steam generator 30 (the vertical direction is shown by the arrow in the figure). The flash spray device 31 is located above the generator water storage tank 35, and the generator outlet 33 is connected to the generator water storage tank 35. This facilitates the collection and storage of spray water sprayed by the flash spray device 31, and makes it easy to recover the spray water and guide it back to the direct contact heat exchanger 10, thus facilitating water recycling.

[0044] More specifically, such as Figure 2 As shown, a hot water pipe 41 connects the heat exchanger outlet 15 to the generator inlet 32, a cold water pipe 42 connects the heat exchanger inlet 14 to the generator outlet 33, and a steam pipe 43 connects the steam outlet 34 to the first heat pump inlet 23. This facilitates the piping connection of the direct-contact heat exchanger 10, the closed-loop steam generator 30, and the heat pump equipment 20, and facilitates the guidance of cold water, hot water, and steam.

[0045] Optionally, the second heat pump inlet 25 is suitable for introducing softened water, and the second heat pump outlet 26 is suitable for discharging water or steam. Using softened water can reduce scale formation and lower maintenance costs. The second heat pump outlet 26 can be selected to discharge water or steam according to the needs of the heat-using equipment.

[0046] Figure 1 and Figure 2 A waste heat recovery system 1 for a papermaking process according to some examples of the present invention is shown. For example... Figure 1 and Figure 2 As shown, a heat exchanger water storage tank 16 is formed at the bottom of the direct-contact heat exchanger 10, and a heat exchanger spraying device 11 is located above the heat exchanger water storage tank 16. The heat exchanger air inlet 12 is located vertically between the heat exchanger spraying device 11 and the heat exchanger water storage tank 16. This facilitates the collection and storage of the spray water sprayed by the heat exchanger spraying device 11, and facilitates the recovery of the hot water generated after spraying and its guidance to the waste heat recovery device, thus facilitating the recovery of waste heat from the hot water.

[0047] Optionally, both the hot water pipe 41 and the cold water pipe 42 are connected to on / off valves and fluid state detection devices, and at least one of the hot water pipe 41 and the cold water pipe 42 is connected to a water pump. Specifically, the fluid state detection device may include one or more of a water temperature sensor, a flow sensor, and a pressure sensor. The on / off valve facilitates the control of the pipe's opening and closing, and controls the liquid flow direction according to actual needs. The fluid state detection device facilitates the detection of the fluid state, and facilitates the monitoring of the operation of the papermaking process waste heat recovery system 1. The water pump provides the driving force for the circulation of water, facilitating the smooth flow of water.

[0048] Optionally, the heat exchanger exhaust port 13 is connected to the atmosphere. This allows the air inside the direct-touch heat exchanger 10, after being cooled, dehumidified, and cleaned, to be discharged into the atmosphere, facilitating air release.

[0049] Other components and operations of the waste heat recovery system 1 for papermaking process according to the embodiments of this utility model are known to those skilled in the art and will not be described in detail here.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A waste heat recovery system for papermaking process, characterized in that, include: A direct-contact heat exchanger is provided with a heat exchanger spray device. The direct-contact heat exchanger is provided with a heat exchanger air inlet, a heat exchanger exhaust outlet, a heat exchanger water inlet, and a heat exchanger water outlet. The heat exchanger air inlet is suitable for introducing humid and hot air generated by the papermaking process. The heat exchanger water inlet is connected to the heat exchanger spray device. A waste heat recovery device is connected to the inlet and outlet of the heat exchanger and is adapted to recover waste heat from the hot water discharged from the outlet of the heat exchanger.

2. The waste heat recovery system for papermaking process according to claim 1, characterized in that, The waste heat recovery device includes a heat pump device, which has a first flow channel and a second flow channel. The first flow channel and the second flow channel are adapted to exchange heat within the heat pump device. The heat pump device is provided with a first heat pump inlet, a first heat pump outlet, a second heat pump inlet, and a second heat pump outlet. The two ends of the first flow channel are respectively connected to the first heat pump inlet and the first heat pump outlet. The two ends of the second flow channel are respectively connected to the second heat pump inlet and the second heat pump outlet. The first heat pump inlet is connected to the outlet of the heat exchanger, the first heat pump outlet is connected to the inlet of the heat exchanger, and the second heat pump inlet and the second heat pump outlet are connected to the heat-using equipment.

3. The waste heat recovery system for papermaking process according to claim 2, characterized in that, A hot water pipe is connected between the first heat pump inlet and the heat exchanger outlet, and a cold water pipe is connected between the first heat pump outlet and the heat exchanger inlet.

4. The waste heat recovery system for papermaking process according to claim 1, characterized in that, The waste heat recovery device includes: A heat pump device has a first flow channel and a second flow channel, which are adapted to exchange heat within the heat pump device. The heat pump device is provided with a first heat pump inlet, a first heat pump outlet, a second heat pump inlet, and a second heat pump outlet. The two ends of the first flow channel are respectively connected to the first heat pump inlet and the first heat pump outlet, and the two ends of the second flow channel are respectively connected to the second heat pump inlet and the second heat pump outlet. The second heat pump inlet and the second heat pump outlet are connected to a heat-using device. A closed-loop steam generator is provided with a generator inlet, a generator outlet, and a steam outlet. A flash spray device is provided inside the closed-loop steam generator. The generator inlet is connected to the flash spray device. The generator inlet is connected to the heat exchanger outlet. The generator outlet is connected to the heat exchanger inlet. The steam outlet is connected to the inlet of a first heat pump. The outlet of the first heat pump is suitable for discharging condensate.

5. The waste heat recovery system for papermaking process according to claim 4, characterized in that, The bottom of the closed steam generator has a generator water storage tank, the flash spray device is located above the generator water storage tank, and the generator outlet is connected to the generator water storage tank.

6. The waste heat recovery system for papermaking process according to claim 4, characterized in that, A hot water pipe is connected between the heat exchanger outlet and the generator inlet, a cold water pipe is connected between the heat exchanger inlet and the generator outlet, and a steam pipe is connected between the steam outlet and the first heat pump inlet.

7. The waste heat recovery system for papermaking process according to any one of claims 2-6, characterized in that, The second heat pump inlet is suitable for introducing softened water, and the second heat pump outlet is suitable for discharging water or steam.

8. The waste heat recovery system for papermaking process according to claim 1, characterized in that, The bottom of the direct-contact heat exchanger has a heat exchanger water tank, the heat exchanger spray device is located above the heat exchanger water tank, and the heat exchanger air inlet is located between the heat exchanger spray device and the heat exchanger water tank in the vertical direction.

9. The waste heat recovery system for papermaking process according to claim 3 or 6, characterized in that, Both the hot water pipe and the cold water pipe are connected to on / off valves and fluid status detection devices, and at least one of the hot water pipe and the cold water pipe is connected to a water pump.

10. The waste heat recovery system for papermaking process according to claim 1, characterized in that, The heat exchanger exhaust port is open to the atmosphere.

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