Waste heat recovery system for papermaking process

Abstract

The invention 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 a heat exchanger air inlet, a heat exchanger air outlet, a heat exchanger water inlet and a heat exchanger water outlet are formed in the direct contact type heat exchanger. 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 papermaking process waste heat recovery system has the advantages that waste heat recovery is sufficient and thorough, corrosion of the heat exchanger is avoided, the maintenance cost is low, and emission pollution is small.

Description

Technical Field

[0001] The present invention relates to the technical field of papermaking, and in particular to a waste heat recovery system for a papermaking process. Background Art

[0002] A large amount of waste heat is generated in the papermaking and drying process of paper mills. This waste heat mainly comes from the paper drying process, which uses hot air to dry the paper. During the drying process, the hot air takes away the moisture on the surface of the paper, forming hot and humid air.

[0003] The temperature of the wet air discharged from the papermaking drying process is 70-80°C. In order to effectively utilize this waste heat, the paper mill adopts a waste heat recovery system to collect the waste heat generated during the drying process and reuse it in other aspects of papermaking production.

[0004] The waste heat recovery system of the papermaking process in the related art uses a partition-type 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 of the papermaking process dryer contains organic components in the papermaking material, which will 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, resulting in increased operation and maintenance costs. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a waste heat recovery system for papermaking process, which has the advantages of sufficient and thorough waste heat recovery, avoiding corrosion of heat exchangers, low maintenance cost, and low emission pollution.

[0006] To achieve the above-mentioned purpose, a papermaking process waste heat recovery system is proposed according to an embodiment of the present invention, and the papermaking process waste heat recovery system comprises: a direct-contact heat exchanger, a heat exchanger spray device is arranged in the direct-contact heat exchanger, a heat exchanger air inlet, a heat exchanger exhaust port, a heat exchanger water inlet and a heat exchanger water outlet are arranged on the direct-contact heat exchanger, the heat exchanger air inlet is suitable for introducing humid hot air generated by the papermaking process, and the heat exchanger water inlet is connected with the heat exchanger spray device; a waste heat recovery device, the waste heat recovery device is respectively connected 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.

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

[0008] In addition, the papermaking process waste heat recovery system according to the above embodiment of the present invention 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, the heat pump device has a first flow channel and a second flow channel, the first flow channel and the second flow channel are suitable for heat exchange in 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 water outlet of the heat exchanger, the first heat pump outlet is connected to the water 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 water outlet of the heat exchanger, and a cold water pipe is connected between the first heat pump outlet and the water inlet of the heat exchanger.

[0011] According to one embodiment of the present invention, the waste heat recovery device includes: a heat pump device, the heat pump device has a first flow channel and a second flow channel, the first flow channel and the second flow channel are suitable for heat exchange in 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 second heat pump inlet and the second heat pump outlet are connected to the heat-using device; a closed steam generator, the closed steam generator is provided with a generator water inlet, a generator water outlet and a steam outlet, the closed steam generator is provided with a flash spray device, the generator water inlet is connected to the flash spray device, the generator water inlet is connected to the heat exchanger water outlet, the generator water outlet is connected to the heat exchanger water inlet, the steam outlet is connected to the first heat pump inlet, and the first heat pump outlet is suitable for discharging condensed water.

[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 water 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 water outlet of the heat exchanger and the water inlet of the generator, a cold water pipe is connected between the water inlet of the heat exchanger and the water outlet of the generator, and a steam pipe is connected between the steam outlet and the inlet of the first heat pump.

[0014] According to one embodiment of the present invention, the second heat pump inlet is suitable for introducing softened water, and the second heat pump outlet is suitable for discharging water or steam.

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

[0016] According to one embodiment of the present invention, both the hot water pipe and the cold water pipe are connected with an on-off valve and a fluid state detection device, and at least one of the hot water pipe and the cold water pipe is connected with a water pump.

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

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

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

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

[0022] Figure numerals: papermaking process waste heat recovery system 1, direct contact heat exchanger 10, heat exchanger spray device 11, heat exchanger air inlet 12, heat exchanger exhaust port 13, heat exchanger water inlet 14, heat exchanger water outlet 15, heat exchanger water storage tank 16, heat pump equipment 20, first flow channel 21, second flow channel 22, first heat pump inlet 23, first heat pump outlet 24, second heat pump inlet 25, second heat pump outlet 26, closed steam generator 30, flash spray device 31, generator water inlet 32, generator water outlet 33, steam outlet 34, generator water storage tank 35, hot water pipe 41, cold water pipe 42, steam pipe 43. DETAILED DESCRIPTION

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

[0024] The waste heat recovery system of the papermaking process in the related art adopts a partition-type heat exchanger. The exhaust gas of the papermaking process dryer contains organic components in the papermaking material, which will contaminate the surface of the heat exchanger and reduce its heat transfer efficiency. In severe cases, it will cause corrosion to the surface of the heat exchanger, resulting in increased operation and maintenance costs.

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The following describes a papermaking process waste heat recovery system 1 according to an embodiment of the present invention with reference to the accompanying drawings.

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

[0030] A heat exchanger spray device 11 is provided in the direct contact heat exchanger 10, and 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 are provided on the direct contact heat exchanger 10. The heat exchanger air inlet 12 is suitable for introducing hot and humid air generated by the papermaking process, and the heat exchanger water inlet 14 is connected to the heat exchanger spray device 11. The waste heat recovery device is respectively connected to the heat exchanger water inlet 14 and the heat exchanger water outlet 15 and is suitable for recovering waste heat in hot water discharged from the heat exchanger water outlet 15.

[0031] Specifically, the hot and humid air generated by the papermaking drying process enters the direct-contact heat exchanger 10 through the heat exchanger air inlet 12, and the heat exchanger spray device 11 sprays the hot and humid air entering the direct-contact heat exchanger 10. The spray water directly contacts the hot and humid air for heat exchange. The air temperature and humidity are reduced and then discharged through the heat exchanger exhaust port 13. The spray water temperature is increased and then discharged through the heat exchanger water outlet 15. The hot water enters the waste heat recovery device to recover the waste heat and after cooling, it enters the heat exchanger spray device 11 through the heat exchanger water inlet 14 for spraying water.

[0032] According to the papermaking process waste heat recovery system 1 of the embodiment of the present invention, a direct-contact heat exchanger 10 is provided, and the heat exchanger spraying device 11 of the direct-contact heat exchanger 10 is used to directly spray the humid hot air generated by the papermaking process, so that the spraying water directly contacts the humid hot air for heat exchange, cools and dehumidifies the humid hot air, and generates hot water for recycling by the waste heat recovery device. Compared with the papermaking process waste heat recovery system using a partition heat exchanger in the related art, since the spraying water is in direct contact with the humid hot air generated by the papermaking process, not only can the heat exchange efficiency and heat exchange effect be improved, but also the waste heat can be recovered more effectively, and the waste heat recovery can be made more sufficient and thorough, and the temperature of the high-temperature and high-humidity air can be reduced to below 30°C, which is much lower than the waste heat recovery level of more than 40°C in the related art, and the moisture in the air can be absorbed to reduce the air humidity.

[0033] In addition, the waste heat recovery system of the papermaking process in the related art adopts a partition-type heat exchanger. The exhaust gas of the papermaking process dryer contains organic components in the papermaking material, which will pollute the surface of the heat exchanger, reduce its heat transfer efficiency, and in severe cases cause corrosion to the surface of the heat exchanger, resulting in increased operation and maintenance costs. The waste heat recovery system 1 of the papermaking process can prevent the organic components of the papermaking material in the humid hot air from polluting the surface of the heat exchanger, avoiding affecting the heat transfer efficiency of the heat exchanger, avoiding corrosion of the surface of the heat exchanger, and reducing the maintenance cost of the direct contact heat exchanger 10 by spraying humid hot air with the heat exchanger spray device 11.

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

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

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

[0037] In some specific embodiments of the present invention, Figure 1 and Figure 2 As shown, the papermaking process waste heat recovery system 1 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, 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 suitable for heat exchange in 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, 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 first heat pump inlet 23 is connected to the heat exchanger water outlet 15, the first heat pump outlet 24 is connected to the heat exchanger water inlet 14, and the second heat pump inlet 25 and the second heat pump outlet 26 are connected to the heat-using device. In this way, the hot water discharged from the heat exchanger outlet 15 enters the heat pump device 20 through the first heat pump inlet 23, exchanges heat with the water in the second flow channel 22 in the first flow channel 21, and flows back to the heat exchanger spray device 11 as spray water through the first heat pump outlet 24 and the heat exchanger inlet 14 after cooling down. The cold water entering the second flow channel 22 from the second heat pump inlet 25 is discharged through the second heat pump outlet 26 after the temperature rises after the heat exchange between the first flow channel 21 and the second flow channel 22, and flows to the heat-using device to realize heat recovery. In this way, the heat pump device 20 can be used to exchange heat with the water in the first flow channel 21 and the second flow channel 22, and the residual heat in the hot water discharged from the heat exchanger outlet 15 can be recovered for use in other heat-using devices.

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

[0040] Specifically, Figure 1 As shown, a hot water pipe 41 is connected between the first heat pump inlet 23 and the heat exchanger water outlet 15, and a cold water pipe 42 is connected between the first heat pump outlet 24 and the heat exchanger water inlet 14. This makes it easier to connect the pipelines of the direct-contact heat exchanger 10 and the heat pump device 20, and facilitates the guidance of cold water and hot water.

[0041] In other embodiments, Figure 2 As shown, the waste heat recovery device includes a heat pump device 20 and a closed steam generator 30. The heat pump device 20 has a first flow channel 21 and a second flow channel 22, which are suitable for heat exchange in 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, 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 device. The closed steam generator 30 is provided with a generator water inlet 32, a generator water outlet 33 and a steam outlet 34. A flash spray device 31 is provided inside the closed steam generator 30. The generator water inlet 32 ​​is connected to the flash spray device 31, the generator water inlet 32 ​​is connected to the heat exchanger water outlet 15, the generator water outlet 33 is connected to the heat exchanger water 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 condensed water. Specifically, the hot water discharged from the heat exchanger water outlet 15 enters the flash spray device 31 through the generator water inlet 32 ​​for spraying, so that flash evaporation occurs in the closed steam generator 30 to generate low-temperature and low-pressure water vapor. After the water temperature is reduced, it is discharged through the generator water outlet 33, and the heat exchanger spray device 11 flowing to the heat exchanger water inlet 14 serves as the spray water of the direct contact heat exchanger 10. The water vapor generated by the closed steam generator 30 is discharged through the steam outlet 34, enters the heat pump device 20 through the first heat pump inlet 23, exchanges heat with the water in the second flow channel 22 in the first flow channel 21, and is discharged as condensed water through the first heat pump outlet 24 after the steam condenses and releases heat. The cold water entering the second flow channel 22 through the second heat pump inlet 25 passes through the heat exchange between the first flow channel 21 and the second flow channel 22, and heats the water in the second flow channel 22 through the condensation and heat release of the steam in the first flow channel 21. After the temperature rises, it is discharged through the second heat pump outlet 26 and flows to the heat-using device to realize heat recovery. In this way, the hot water generated by the direct-contact heat exchanger 10 can be used to generate steam in the closed steam generator 30, and the water in the second flow channel 22 is heated by the condensation and heat release of the steam in the heat pump device 20, thereby realizing the recovery of the waste heat in the hot water discharged from the heat exchanger outlet 15 for use in other heat-using devices.

[0042] Specifically, the condensed water discharged from the first heat pump outlet 24 can be used as replenishment water for the papermaking process, and can also be used as replenishment water for the waste heat recovery system 1 of the papermaking process.

[0043] Advantageously, if Figure 2As shown, a generator water storage tank 35 (the up and down directions are shown by arrows in the figure) is formed at the bottom of the closed steam generator 30, and a flash spray device 31 is arranged above the generator water storage tank 35, and a generator water outlet 33 is connected to the generator water storage tank 35. In this way, it is convenient to collect and store the spray water sprayed by the flash spray device 31, and it is convenient to recover the spray water and guide it back to the direct contact heat exchanger 10, so as to facilitate the recycling of water.

[0044] More specifically, Figure 2 As shown, a hot water pipe 41 is connected between the heat exchanger water outlet 15 and the generator water inlet 32, a cold water pipe 42 is connected between the heat exchanger water inlet 14 and the generator water outlet 33, and a steam pipe 43 is connected between the steam outlet 34 and the first heat pump inlet 23. This makes it easier to connect the pipelines of the direct-contact heat exchanger 10, the closed steam generator 30 and the heat pump device 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 the generation of scale and reduce maintenance costs. The second heat pump outlet 26 can choose to discharge water or steam according to the needs of the heat-using equipment.

[0046] Figure 1 and Figure 2 The papermaking process waste heat recovery system 1 according to some examples of the present invention is shown. 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, the heat exchanger spray device 11 is arranged above the heat exchanger water storage tank 16, and the heat exchanger air inlet 12 is located between the heat exchanger spray device 11 and the heat exchanger water storage tank 16 in the vertical direction. In this way, it is convenient to collect and store the spray water sprayed by the heat exchanger spray device 11, to recover the hot water generated after spraying and guide it to the waste heat recovery device, and to recover the waste heat in the hot water.

[0047] Optionally, both the hot water pipe 41 and the cold water pipe 42 are connected with an on-off valve and a fluid state detection device, and at least one of the hot water pipe 41 and the cold water pipe 42 is connected with 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 can facilitate the on-off control of the pipeline and control the flow direction of the liquid according to actual needs. The fluid state detection device can facilitate the detection of the fluid state and the monitoring of the operation of the papermaking process waste heat recovery system 1. The water pump can provide a 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, so that the air in the direct contact heat exchanger 10 that has been cooled, dehumidified and cleaned can be discharged into the atmosphere, which is convenient for air discharge.

[0049] Other structures and operations of the papermaking process waste heat recovery system 1 according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

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

Claims

1. A papermaking process waste heat recovery system, characterized in that: include: A direct contact heat exchanger, wherein a heat exchanger spray device is provided in the direct contact heat exchanger, and a heat exchanger air inlet, a heat exchanger exhaust port, a heat exchanger water inlet and a heat exchanger water outlet are provided on the direct contact heat exchanger, wherein the heat exchanger air inlet is suitable for introducing hot and humid air generated by the papermaking process, and the heat exchanger water inlet is connected to the heat exchanger spray device; A waste heat recovery device is respectively connected to the water inlet of the heat exchanger and the water outlet of the heat exchanger and is suitable for recovering waste heat in the hot water discharged from the water outlet of the heat exchanger.

2. The papermaking process waste heat recovery system 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 suitable for heat exchange in 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 water outlet of the heat exchanger, the first heat pump outlet is connected to the water inlet of the heat exchanger, and the second heat pump inlet and the second heat pump outlet are connected to the heat-using device.

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

4. The papermaking process waste heat recovery system according to claim 1, characterized in that: The waste heat recovery device comprises: A heat pump device, wherein the heat pump device has a first flow channel and a second flow channel, the first flow channel and the second flow channel are suitable for heat exchange in 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, and the second heat pump inlet and the second heat pump outlet are connected to a heat-using device; A closed steam generator, wherein the closed steam generator is provided with a generator water inlet, a generator water outlet and a steam outlet, a flash spray device is provided inside the closed steam generator, the generator water inlet is connected to the flash spray device, the generator water inlet is connected to the heat exchanger water outlet, the generator water outlet is connected to the heat exchanger water inlet, the steam outlet is connected to the first heat pump inlet, and the first heat pump outlet is suitable for discharging condensed water.

5. The papermaking process waste heat recovery system according to claim 4, characterized in that: 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 water outlet is connected to the generator water storage tank.

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

7. The papermaking process waste heat recovery system according to any one of claims 2 to 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 papermaking process waste heat recovery system according to claim 1, characterized in that: A heat exchanger water storage tank is formed at the bottom of the direct-contact heat exchanger, the heat exchanger spray device is arranged above the heat exchanger water storage tank, and the heat exchanger air inlet is located between the heat exchanger spray device and the heat exchanger water storage tank in the up and down directions.

9. The papermaking process waste heat recovery system according to claim 3 or 6, characterized in that: The hot water pipe and the cold water pipe are both connected with an on-off valve and a fluid state detection device, and at least one of the hot water pipe and the cold water pipe is connected with a water pump.

10. The papermaking process waste heat recovery system according to claim 1, characterized in that: The exhaust port of the heat exchanger is communicated with the atmosphere.

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