Wastewater recycling system and recycling method

Abstract

The present disclosure relates to a sewage recovery system and a recovery method. The sewage recovery system comprises: a first heat exchanger having a first inlet, a first outlet, a second inlet and a second outlet, the first inlet being used to introduce a gaseous refrigerant, the first outlet being connected to the first inlet and being used to discharge a liquid refrigerant formed by condensation heat exchange between the gaseous refrigerant and the sewage; the second inlet being used to introduce sewage, the second outlet being used to discharge water vapor formed by evaporation heat exchange between the sewage and the gaseous refrigerant; and a second heat exchanger having a third inlet, a third outlet, a fourth inlet and a fourth outlet, the third inlet being used to introduce condensed water formed by water vapor, the third outlet being connected to the third inlet and being used to discharge condensed water after heat exchange with sewage to be recovered; the fourth inlet being used to introduce sewage to be recovered, the fourth outlet being connected to both the fourth inlet and the second inlet and being used to allow the sewage after heat exchange with the condensed water to enter the first heat exchanger.

Description

Technical Field

[0001] The present disclosure relates to the technical field of sewage recycling, and in particular to a sewage recycling system and a recycling method. Background Art

[0002] As the demand for freshwater resources increases, the requirements for water resource recycling and reuse and technology development are also getting higher and higher. Sewage is generally discharged directly into the municipal sewage system or discharged on site after simple treatment, which increases the load of municipal sewage treatment and even directly loses this part of water resources. Sewage has problems such as high pollutant concentration and high conductivity. Direct use will increase the risks of equipment corrosion, scaling, pipe blockage, etc., so it is necessary to recycle sewage.

[0003] At present, the main technologies for recycling wastewater include distillation, membrane, electrodialysis and freezing, but the wastewater recycling efficiency of these devices is low. Summary of the invention

[0004] The present invention provides a sewage recovery system and a sewage recovery method, which can improve sewage recovery efficiency.

[0005] According to one aspect of the present disclosure, there is provided a sewage recovery system, comprising:

[0006] a first heat exchanger having a first inlet, a first outlet, a second inlet, and a second outlet, wherein the first inlet is used to introduce a gaseous refrigerant, and the first outlet is connected to the first inlet and is used to discharge a liquid refrigerant formed by condensation heat exchange between the gaseous refrigerant and the sewage; the second inlet is used to introduce sewage, and the second outlet is used to discharge water vapor formed by evaporation heat exchange between the sewage and the gaseous refrigerant; and

[0007] The second heat exchanger has a third inlet, a third outlet, a fourth inlet and a fourth outlet. The third inlet is used to allow condensed water formed by water vapor to pass through. The third outlet is connected to the third inlet and is used to discharge the condensed water after heat exchange with the sewage to be recycled. The fourth inlet is used to allow sewage to be recycled through. The fourth outlet is connected to both the fourth inlet and the second inlet and is used to allow the sewage after heat exchange with the condensed water to pass into the first heat exchanger.

[0008] In some embodiments, the wastewater recycling system further comprises:

[0009] compressor; and

[0010] The third heat exchanger has a fifth inlet, a fifth outlet, a sixth inlet and a sixth outlet. The fifth inlet is connected to the first outlet, the fifth outlet is connected to the first inlet through the compressor, the sixth inlet is connected to the second outlet, and the sixth outlet is connected to the sixth inlet and the third inlet. The third heat exchanger is used to exchange heat between liquid refrigerant and water vapor to achieve phase change.

[0011] In some embodiments, the sewage recovery system also includes: a first pipeline and a second pipeline in parallel, and the first ends of the first pipeline and the second pipeline are respectively connected to the sixth outlet, and the second ends of the first pipeline and the second pipeline are respectively connected to the third inlet, the first pipeline is used to accommodate the gas in the condensed water, and a gas-liquid separator is provided in the second pipeline.

[0012] In some embodiments, the wastewater recycling system further comprises:

[0013] a liquid level detection component, disposed in the first pipeline, for detecting the liquid level of condensed water in the first pipeline; and

[0014] The first on-off valve and the second on-off valve are arranged on the first pipeline and are respectively located on both sides of the liquid level detection component.

[0015] In some embodiments, the wastewater recycling system further comprises:

[0016] A third pipeline is connected to the third outlet and is used to discharge condensed water;

[0017] a negative pressure pump, disposed on the third pipeline; and

[0018] The exhaust valve is arranged on the third pipeline and located at the inlet of the negative pressure pump. The exhaust valve is connected to the first pipeline and is used to exhaust the gas in the condensed water when it is opened.

[0019] In some embodiments, the sewage recovery system further includes a connecting pipe, through which the exhaust valve is connected to the first pipeline.

[0020] In some embodiments, the wastewater recycling system further comprises:

[0021] A third pipeline connected to the third outlet for conducting condensed water; and

[0022] The negative pressure pump is arranged on the third pipeline and is used for maintaining negative pressure in the first heat exchanger.

[0023] In some embodiments, the negative pressure pump is a variable frequency pump, and the operating frequency is configured to be adjusted according to the demand for condensed water and / or the amount of condensed water generated.

[0024] In some embodiments, the wastewater recycling system further comprises:

[0025] A third pipeline connected to the third outlet for conducting condensed water; and

[0026] The one-way valve is arranged on the third pipeline and is used for allowing only the condensed water to flow in one direction along the third pipeline from the third outlet.

[0027] In some embodiments, the first heat exchanger further has a slag outlet, and the sewage recovery system further comprises:

[0028] a slag container having a seventh inlet and a seventh outlet, wherein the seventh inlet is connected to the slag outlet; and

[0029] The sludge drying container is connected to the seventh outlet.

[0030] In some embodiments, the wastewater recycling system further comprises:

[0031] a fourth on-off valve, provided on the pipeline between the slag outlet and the seventh inlet; and / or

[0032] The fifth on-off valve is arranged on the pipeline between the seventh outlet and the sludge drying container.

[0033] In some embodiments, the sediment container has a water inlet, and the sewage recovery system further comprises:

[0034] The fourth pipeline has two ends connected with the fifth pipeline and the water inlet respectively. The fifth pipeline is used to introduce the sewage to be treated. The fourth pipeline is provided with a sixth on-off valve to allow water to enter the sediment container when the sixth on-off valve is connected.

[0035] According to another aspect of the present disclosure, a recycling method based on the sewage recycling system of the above embodiment is provided, comprising:

[0036] The sewage to be recycled is heat-exchanged with condensed water recovered from the sewage by a second heat exchanger to preheat the sewage to be recycled, and the condensed water is discharged after heat exchange;

[0037] The preheated sewage is heat-exchanged with the gaseous refrigerant through the first heat exchanger, so that the gaseous refrigerant is condensed and heat-exchanged to form liquid refrigerant, and the sewage is evaporated and heat-exchanged to form water vapor to form condensed water and enter the second heat exchanger.

[0038] In some embodiments, the recycling method further comprises:

[0039] The liquid refrigerant and water vapor are exchanged with heat through the third heat exchanger, so that the liquid refrigerant evaporates and exchanges heat to form a gaseous refrigerant, which enters the first heat exchanger after being compressed by the compressor, and the water vapor is condensed and exchanged to form condensed water that enters the second heat exchanger.

[0040] In some embodiments, a first pipeline and a second pipeline are connected in parallel between the second heat exchanger and the third heat exchanger, the first pipeline is used to contain gas in condensed water, a gas-liquid separator is provided on the second pipeline, a liquid level detection component is provided on the first pipeline, and a first on-off valve and a second on-off valve are respectively provided on both sides of the liquid level detection component on the first pipeline; the recovery method further includes:

[0041] During the sewage recovery process, the first on-off valve and the second on-off valve are both in an on state;

[0042] When the liquid level detection component needs maintenance, both the first on-off valve and the second on-off valve are in an off state.

[0043] In some embodiments, the wastewater recovery system further includes: a third pipeline for conducting condensed water passing through the first heat exchanger; and a negative pressure pump disposed on the third pipeline; and the recovery method further includes:

[0044] During the wastewater recovery process, the operating frequency of the negative pressure pump is adjusted according to the demand load of condensed water and / or the amount of condensed water generated.

[0045] In some embodiments, the first heat exchanger further has a slag outlet, and the sewage recovery system further includes: a sludge container having a seventh inlet and a seventh outlet, the seventh inlet being connected to the slag outlet; and a sludge drying container being connected to the seventh outlet; wherein a fourth on-off valve is provided on the pipeline between the slag outlet and the seventh inlet, and a fifth on-off valve is provided on the pipeline between the seventh outlet and the sludge drying container; and the recovery method further includes:

[0046] During the sewage recovery process, the fourth on-off valve is in an on state, and the fifth on-off valve is in an off state;

[0047] During the slag discharge process, the fourth on-off valve is in an off state, and the fifth on-off valve is in an on state, so that the sludge in the sediment container is discharged into the sludge drying container.

[0048] In some embodiments, the sediment container has a water inlet, and the sewage recovery system further includes: a fourth pipeline, both ends of which are connected to the fifth pipeline and the water inlet respectively, the fifth pipeline is used to pass the sewage to be treated, and a sixth on-off valve is provided on the fourth pipeline; the recovery method also includes:

[0049] After the slag discharge is completed, the sixth on-off valve is turned on to allow water to flow into the sludge container to remove the sludge;

[0050] After the preset flushing time, the fifth on-off valve is in an off state, and water continues to flow into the sediment container so that the sediment container is filled with water;

[0051] After the water filling is completed, the fourth on-off valve is in the on state, and the fifth on-off valve and the sixth on-off valve are in the off state.

[0052] The sewage recovery system of the disclosed embodiment, by setting a second heat exchanger, exchanges heat between the condensed water obtained after sewage evaporation and sewage to be treated, so that the latent heat after sewage evaporation and recovery can be fully utilized in the sewage to be recovered, so as to increase the temperature of the sewage to be treated, thereby accelerating the evaporation of the sewage in the first heat exchanger to form water vapor, which can improve the sewage treatment efficiency, increase the operating efficiency of the sewage recovery system, reduce the energy consumption of the device operation, and save energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0054] Figure 1 Schematic diagram of the structure of some embodiments of the sewage recovery system disclosed in the present invention.

[0055] Description of Reference Numerals

[0056] 1. First heat exchanger; 11. First inlet; 12. First outlet; 13. Second inlet; 14. Second outlet; 15. Slag outlet;

[0057] 2. Second heat exchanger; 21. Third inlet; 22. Third outlet; 23. Fourth inlet; 24. Fourth outlet;

[0058] 3. Third heat exchanger; 31. Fifth inlet; 32. Fifth outlet; 33. Sixth inlet; 34. Sixth outlet;

[0059] 4. compressor; 41. air inlet; 42. exhaust port;

[0060] 5. Liquid level detection component; 5', gas-liquid separator; 6. One-way valve; 7. Negative pressure pump;

[0061] 71. First on-off valve; 72. Second on-off valve; 73. Third on-off valve; 74. Fourth on-off valve; 75. Fifth on-off valve; 76. Sixth on-off valve; 77. Flow regulating valve; 78. Eighth on-off valve;

[0062] 8. Exhaust valve; 9. Sediment container; 91. Seventh inlet; 92. Seventh outlet; 93. Water inlet; 10. Sludge drying container;

[0063] L1, first pipeline; L2, second pipeline; L3, third pipeline; L4, fourth pipeline; L5, fifth pipeline; L6, sixth pipeline; L7, seventh pipeline; L8, eighth pipeline; L9, ninth pipeline. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without carrying out creative work are within the scope of protection of the present disclosure.

[0065] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0066] In the description of the present disclosure, it is necessary to understand that the terms "center", "lateral", "longitudinal", "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0067] In the description of the present disclosure, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present disclosure.

[0068] The present disclosure provides a wastewater recovery system, and the recovered product is pure water that can be recycled, for example, it can be used for industrial evaporation water, such as air conditioning condensation water, or can also be used in other application occasions.

[0069] In order to better understand the embodiments of the present disclosure, first Figure 1 The different line types and media marks in the figure are explained. The dotted line represents the refrigerant flow pipeline, and the solid line represents the sewage, water vapor and condensed water flow pipeline. WS represents sewage, ZQ represents water vapor and condensed water, and WN represents sludge.

[0070] In some embodiments, Figure 1 As shown, the sewage recycling system includes:

[0071] The first heat exchanger 1 has a first inlet 11, a first outlet 12, a second inlet 13 and a second outlet 14. The first inlet 11 is used to introduce a gaseous refrigerant, and the first outlet 12 is connected to the first inlet 11 and is used to discharge a liquid refrigerant formed by condensation heat exchange between the gaseous refrigerant and the sewage; the second inlet 13 is used to introduce sewage, and the second outlet 14 is used to discharge water vapor formed by evaporation heat exchange between the sewage and the gaseous refrigerant; and

[0072] The second heat exchanger 2 has a third inlet 21, a third outlet 22, a fourth inlet 23 and a fourth outlet 24. The third inlet 21 is used for introducing condensed water formed by water vapor. The third outlet 22 is connected to the third inlet 21 and is used to discharge the condensed water after heat exchange with the sewage to be recycled; the fourth inlet 23 is used for introducing sewage to be recycled. The fourth outlet 24 is connected to both the fourth inlet 23 and the second inlet 13, and is used to allow the sewage after heat exchange with the condensed water to enter the first heat exchanger 1.

[0073] The first heat exchanger 1 is used to realize heat exchange between preheated sewage and gaseous refrigerant, and both sewage and gaseous refrigerant undergo phase change. The second heat exchanger 2 is used to realize heat exchange between condensed water and sewage to be recycled, so as to preheat the sewage to be recycled.

[0074] For example, the first heat exchanger 1 is a shell and tube heat exchanger, including a shell and a heat exchange tube, the heat exchange tube is installed in the shell, the refrigerant is passed into the heat exchange tube, and the sewage is passed into the shell to increase the treatment volume when the sewage evaporates and increase the sewage recovery efficiency. The second heat exchanger 2 can be a plate heat exchanger, and two heat exchange channels can be set inside to flow condensed water and sewage to be treated respectively.

[0075] Specifically, the second heat exchanger 2 is used to preheat the sewage to be treated. The preheated sewage enters the first heat exchanger 1 through the second inlet 13 and exchanges heat with the high-temperature gaseous refrigerant entering the first heat exchanger 1 through the first inlet 11. Both the sewage and the gaseous refrigerant undergo phase change. The gaseous refrigerant condenses and exchanges heat to form liquid refrigerant, which is discharged through the first outlet 12 for refrigerant circulation. The sewage absorbs the heat released by the condensation of the gaseous refrigerant to perform evaporation heat exchange to form water vapor and is discharged through the second outlet 14. This process can also be called distillation.

[0076] After the water vapor condenses to form condensed water, it enters the second heat exchanger 2 through the third inlet 21. The sewage to be treated also enters the second heat exchanger 2 through the fourth inlet 23 through the fifth pipeline L5, and the sewage to be treated is preheated by the condensed water. The preheated sewage is discharged through the fourth outlet 24 and enters the first heat exchanger 1 through the second inlet 13. After heat exchange, the condensed water is discharged through the third outlet 22 and enters the third pipeline L3 for export, so as to realize sewage recovery.

[0077] This embodiment sets a second heat exchanger 2, and exchanges heat between the condensed water obtained after the sewage is evaporated and recovered and the sewage to be treated, so that the latent heat after the sewage is evaporated and recovered can be fully utilized in the sewage to be recovered, so as to increase the temperature of the sewage to be treated, thereby accelerating the evaporation of the sewage in the first heat exchanger 1 to form water vapor, which can improve the sewage treatment efficiency, increase the operating efficiency of the sewage recovery system, reduce the energy consumption of the device operation, and save energy.

[0078] In some embodiments, Figure 1 As shown, the sewage recovery system further includes: a compressor 4 and a third heat exchanger 3. The compressor 4 has an air inlet 41 and an exhaust port 42; and a third heat exchanger 3. The third heat exchanger 3 has a fifth inlet 31, a fifth outlet 32, a sixth inlet 33 and a sixth outlet 34, the fifth inlet 31 is connected to the first outlet 12, the fifth outlet 32 ​​is connected to the first inlet 11 through the compressor 4, the sixth inlet 33 is connected to the second outlet 14, and the sixth outlet 34 is connected to the sixth inlet 33 and the third inlet 21.

[0079] The third heat exchanger 3 is arranged between the first heat exchanger 1 and the second heat exchanger 2, and is used for exchanging heat between the liquid refrigerant and water vapor to achieve phase change. Both the liquid refrigerant and the water vapor achieve phase change. The water vapor undergoes condensation heat exchange to form condensed water. The liquid refrigerant absorbs the heat generated by the condensation heat exchange and evaporates heat exchange to form a low-temperature and low-pressure gaseous refrigerant. After being compressed by the compressor 4, a high-temperature and high-pressure gaseous refrigerant is formed and re-enters the first heat exchanger 1 through the first inlet 11.

[0080] For example, the third heat exchanger 3 may be a plate heat exchanger, and two heat exchange channels may be provided inside thereof, through which water vapor and liquid refrigerant flow respectively.

[0081] Specifically, the liquid refrigerant discharged from the first outlet 12 of the first heat exchanger 1 enters the third heat exchanger 3 through the sixth pipeline L6 and the fifth inlet 31, forms a low-temperature and low-pressure gaseous refrigerant after evaporation and heat exchange with water vapor, and enters the air inlet 41 of the compressor 4 for compression. After compression, the high-temperature and high-pressure gaseous refrigerant is discharged from the exhaust port 42 of the compressor 4 and returns to the first heat exchanger 1 through the first inlet 11, thereby the sixth pipeline L6 and the seventh pipeline L7 form a refrigerant circulation loop.

[0082] At the same time, the water vapor discharged from the second outlet 14 of the first heat exchanger 1 enters the third heat exchanger 3 through the eighth pipeline L8 and the sixth inlet 33, forms condensed water after condensation and heat exchange with the liquid refrigerant, and enters the second heat exchanger 2 through the second pipeline L2 and the third inlet 21, so that the condensed water can preheat the sewage to be recycled in the second heat exchanger 2.

[0083] This embodiment sets a third heat exchanger 3 to condense water vapor to exchange heat to form condensed water, and at the same time uses the heat released during the condensation process to convert liquid refrigerant into gaseous refrigerant, thereby realizing the recycling of refrigerant and making full use of the heat released by the condensation of water vapor, greatly increasing the operating efficiency of the sewage recovery system and reducing the operating energy consumption.

[0084] In some embodiments, the sewage recovery system further includes: a first pipeline L1 and a second pipeline L2 connected in parallel, and the first ends of the first pipeline L1 and the second pipeline L2 are each connected to the sixth outlet 34, and the second ends of the first pipeline L1 and the second pipeline L2 are each connected to the third inlet 21, the first pipeline L1 is used to guide the gas in the condensed water, and the second pipeline L2 is provided with a gas-liquid separator 5'. The gas-liquid separator 5' is used to achieve gas-liquid separation of the condensed water and storage of the condensed water.

[0085] The first pipeline L1 may be a capillary tube with a smaller diameter, etc. The inlet of the gas-liquid separator 5' is connected to the sixth outlet 34, and the outlet of the gas-liquid separator 5' is connected to the third inlet 21. After the condensed water enters the gas-liquid separator 5', the gas-liquid separation is performed, the non-condensable gas enters the first pipeline L1, and the liquid enters the second heat exchanger 2 through the third inlet 21 to preheat the wastewater to be recovered.

[0086] This embodiment arranges the first pipeline L1 and the second pipeline L2 in parallel between the second heat exchanger 2 and the third heat exchanger 3, and arranges a gas-liquid separator 5' on the second pipeline L2, so as to timely separate the non-condensable gas in the condensed water, prevent the gas from accumulating in the pipeline and occupying volume to avoid clogging the pipeline, prevent the non-condensable gas from affecting the process of sewage evaporation to form water vapor, improve the flow efficiency of the liquid in the pipeline, and improve the sewage recovery efficiency.

[0087] In some embodiments, the sewage recovery system also includes: a liquid level detection component 5, arranged in the first pipeline L1, for detecting the liquid level of condensed water in the first pipeline L1; and a first on-off valve 71 and a second on-off valve 72, both arranged on the first pipeline L1, and respectively located on both sides of the liquid level detection component 5.

[0088] For example, the first on-off valve 71 and the second on-off valve 72 may be manual valves or electrically controlled valves.

[0089] Since the first pipeline L1 and the second pipeline L2 are connected, by setting the liquid level detection component 5, the liquid level in the gas-liquid separator 5' can be detected by using the communicating vessel principle, so as to adjust the working frequency of the negative pressure pump 7 mentioned later according to the amount of liquid stored in the gas-liquid separator 5', thereby adjusting the output of the condensed water. Moreover, in the case where the liquid level detection component 5 needs to be maintained, the first on-off valve 71 and the second on-off valve 72 are both in the off state, making the first pipeline L1 independent of the second pipeline L2, and not affecting the sewage treatment process.

[0090] This embodiment is capable of detecting the liquid level in the gas-liquid separator 5' during sewage treatment by providing a liquid level detection component 5, so as to adjust the output of condensed water according to the amount of liquid stored in the gas-liquid separator 5'; moreover, when the first on-off valve 71 and the second on-off valve 72 are turned off, the liquid level detection component 5 can be easily repaired and replaced.

[0091] In one embodiment, the sewage recovery system also includes: a third pipeline L3, connected to the third outlet 22, for discharging condensed water; a negative pressure pump 7, arranged on the third pipeline L3; and an exhaust valve 8, arranged on the third pipeline L3 and located at the inlet of the negative pressure pump 7, and the exhaust valve 8 is connected to the first pipeline L1, and is used to discharge the gas in the condensed water when it is open.

[0092] The exhaust valve 8 is disposed at the inlet of the negative pressure pump 7 , and has a relatively low pressure, so that the non-condensable gas in the first pipeline L1 can flow smoothly toward the exhaust valve 8 .

[0093] This embodiment sets an exhaust valve 8 on the third pipeline L3, which can conveniently and timely discharge the non-condensable gas in the pipeline, prevent the gas from accumulating in the pipeline and occupying volume to avoid clogging the pipeline, prevent the non-condensable gas from affecting the process of sewage evaporation to form water vapor, and improve the flow efficiency of the liquid in the pipeline, thereby improving the sewage recovery efficiency.

[0094] In some embodiments, the sewage recovery system further includes a connecting pipe, and the exhaust valve 8 is connected to the first pipeline L1 through the connecting pipe.

[0095] For example, the connecting tube may be a capillary tube. Figure 1 In the figure, the connecting pipe is not shown because the exhaust valve 8 is far away from the first pipeline L1.

[0096] This embodiment can conveniently achieve communication between the exhaust valve 8 and the first pipeline L1 by providing a connecting pipe, which can reduce the requirements on the positional relationship between the exhaust valve 8 and the first pipeline L1, thereby arranging the exhaust valve 8 more flexibly.

[0097] In some embodiments, the wastewater recovery system further includes: a third pipeline L3 connected to the third outlet 22 for discharging condensed water; and a negative pressure pump 7 provided on the third pipeline L3 for maintaining negative pressure in the first heat exchanger 1 .

[0098] For example, the negative pressure pump 7 may be a negative pressure screw pump or the like.

[0099] This embodiment provides a negative pressure pump 7 on the third pipeline L3, which can not only provide power for the discharge of condensed water to transport the condensed water to the water use point, but also form a negative pressure in the system, which can reduce the evaporation temperature of the sewage. When the temperature in the first heat exchanger 1 is lower than the evaporation temperature under normal pressure, the sewage can evaporate into water vapor, thereby improving the sewage recovery efficiency and reducing the energy consumption of the recovery system.

[0100] Furthermore, by providing the first pipeline L1 to store the non-condensable gas in the condensed water, it is possible to prevent the gas from entering the negative pressure pump 7 and causing the system negative pressure to fail.

[0101] In some embodiments, the negative pressure pump 7 is a variable frequency pump, and the operating frequency is configured to be adjusted according to the demand for condensed water and / or the amount of condensed water generated.

[0102] The amount of condensed water generated can be detected by a liquid level detection component 5 disposed in the first pipeline L1. The liquid level detection component 5 can detect the liquid level of the gas-liquid separator 5' to obtain the amount of condensed water stored inside the gas-liquid separator 5'.

[0103] This embodiment can increase the operating frequency of the negative pressure pump 7 to meet the condensate water supply demand when the external condensate water demand is large or the condensate water generated during the sewage recovery process is large; when the external condensate water demand is small or the condensate water generated during the sewage recovery process is small, reduce the operating frequency of the negative pressure pump 7 to reduce the operating energy consumption of the negative pressure pump 7 on the basis of meeting the condensate water supply demand.

[0104] In some embodiments, the sewage recovery system also includes: a third pipeline L3, connected to the third outlet 22, for discharging condensed water; and a one-way valve 6, arranged on the third pipeline L3, for only allowing condensed water to flow in one direction along the third pipeline L3 from the third outlet 22.

[0105] This embodiment sets a one-way valve 6 in the third pipeline L3 to prevent condensed water from flowing back toward the second heat exchanger 2, and provides pressure protection for the system to prevent external water or gas from being sucked into the system due to increased external pressure or shutdown of the negative pressure pump 7, thereby improving the safety of the recovery system.

[0106] In some embodiments, Figure 1 As shown, the first heat exchanger 1 also has a slag outlet 15 , and the sewage recovery system also includes: a sludge container 9 having a seventh inlet 91 and a seventh outlet 92 , the seventh inlet 91 being connected to the slag outlet 15 ; and a sludge drying container 10 connected to the seventh outlet 92 .

[0107] The slag outlet 15 is arranged at the bottom of the first heat exchanger 1. During the sewage treatment process, the sewage in the first heat exchanger 1 will be deposited in the bottom area of ​​the first heat exchanger 1 and enter the sediment container 9 by gravity. In this process, in order to maintain the negative pressure of the system, the connection between the sediment container 9 and the sludge drying container 10 can be disconnected first; after the sewage treatment is completed, the sludge in the sediment container 9 can be allowed to enter the sludge drying container 10 for drying, and then be transported out after drying.

[0108] This embodiment provides a sediment container 9 and a sludge drying container 10, so that after the sewage in the first heat exchanger 1 is recovered, the sediment can be collected and treated as solid waste after drying, thereby preventing pollution to the environment.

[0109] In some embodiments, the sewage recovery system further includes: a fourth on-off valve 74 disposed on the pipeline between the slag outlet 15 and the seventh inlet 91 ; and / or a fifth on-off valve 75 disposed on the pipeline between the seventh outlet 92 and the sludge drying container 10 .

[0110] The fourth on-off valve 74 and the fifth on-off valve 75 may be manual valves or electrically controlled valves to achieve automation of sewage sediment treatment.

[0111] Specifically, during the sewage treatment process, the fourth on-off valve 74 is in the on state, and the fifth on-off valve 75 is in the off state, so that the sludge at the bottom of the first heat exchanger 1 can enter the sediment container 9, and the negative pressure requirement of the system can be maintained, so as to ensure that the pressure in the first heat exchanger 1 is constant, and the sewage recovery process proceeds smoothly. After the sewage treatment is completed, the fourth on-off valve 74 is first in the off state, and then the fifth on-off valve 75 is in the on state, so that the sludge in the sediment container 9 enters the sludge drying container 10 for drying, and at the same time, the negative pressure in the system can still be maintained during this process.

[0112] This embodiment can flexibly control the discharge and collection process of the sludge by providing the fourth on-off valve 74 and / or the fifth on-off valve 75, and maintain a negative pressure environment in the system during the sludge discharge process.

[0113] In some embodiments, the sediment container 9 has a water inlet 93, and the sewage recovery system also includes: a fourth pipeline L4, whose two ends are respectively connected to the fifth pipeline L5 and the water inlet 93, the fifth pipeline L5 is used to pass the sewage to be treated, and the fourth pipeline L4 is provided with a sixth on-off valve 76 to allow water to enter the sediment container 9 when the sixth on-off valve 76 is connected.

[0114] Among them, after the slag discharge is completed, the sixth on-off valve 76 can be turned on, so that the sewage introduced through the fifth pipeline L5 enters the sediment container 9 through the fourth pipeline L4 for flushing, and the sewage and sludge enter the sludge drying container 10 through the fifth on-off valve 75. After the preset flushing time, the fifth on-off valve 75 is turned off, and water continues to be introduced into the sediment container 9, so that the sediment container 9 is filled with sewage to be treated, so that the sewage completely occupies the space in the sediment container 9. After the fourth on-off valve 74 is turned on in the subsequent sewage treatment process, the negative pressure value in the first heat exchanger 1 is kept unchanged, which is also convenient for subsequent sedimentation. After the water filling is completed, the fifth on-off valve 75 and the sixth on-off valve 76 can be turned off, and the fourth on-off valve 74 can be turned on to maintain the system pressure for sewage recovery.

[0115] This embodiment can, after the sludge in the sediment container 9 is discharged into the sludge drying container 10, open the sixth on-off valve 76 to introduce the sewage to be treated, so as to flush the sediment container 9, thereby removing the sludge in time and preventing the sludge from accumulating in the sediment container 9; moreover, after removing the sludge in the sediment container 9, the sediment container 9 can be filled with water in time, so that the sewage completely occupies the space in the sediment container 9, and after the fourth on-off valve 74 is turned on in the subsequent sewage treatment process, the negative pressure value in the first heat exchanger 1 can be kept unchanged, which is also convenient for subsequent sedimentation.

[0116] Combine the following Figure 1 A specific embodiment of the sewage recovery system disclosed in the present invention is given.

[0117] The sewage recovery system includes a first heat exchanger 1, a second heat exchanger 2, a third heat exchanger 3 and a compressor 4. The first heat exchanger 1 has a first inlet 11, a first outlet 12, a second inlet 13 and a second outlet 14, the second heat exchanger 2 has a third inlet 21, a third outlet 22, a fourth inlet 23 and a fourth outlet 24, and the third heat exchanger 3 has a fifth inlet 31, a fifth outlet 32, a sixth inlet 33 and a sixth outlet 34.

[0118] For the third heat exchanger 3, its fifth inlet 31 is connected to the first outlet 12 through the sixth pipeline L6, the fifth outlet 32 ​​is connected to the fifth inlet 31, and is connected to the first inlet 11 through the compressor 4 in the seventh pipeline L7, the sixth inlet 33 is connected to the second outlet 14 through the eighth pipeline L8, and the sixth outlet 34 is connected to the sixth inlet 33 and is connected to the third inlet 21.

[0119] For the second heat exchanger 2, its third inlet 21 is connected to the sixth outlet 34, the third outlet 22 is connected to the third inlet 21, and the condensed water is discharged through the third pipeline L3, the fourth inlet 23 is connected to the fifth pipeline L5 to allow the sewage to be recycled to pass, and the fourth outlet 24 is connected to the second inlet 13 through the ninth pipeline L9.

[0120] Among them, the fifth pipeline L5 is provided with a flow regulating valve 77 for adjusting the inlet flow of sewage. The third pipeline L3 is provided with an exhaust valve 8, a negative pressure pump 7 and a one-way valve 6 in sequence along the discharge direction of condensed water. The exhaust valve 8 is used to discharge non-condensable gas in the condensed water when opened; the negative pressure pump 7 is used to provide power for the discharge of condensed water and provide negative pressure for the system to facilitate evaporation; the one-way valve 6 is used to prevent external gas or liquid from entering the system; the exhaust valve 8 is connected to the first pipeline L1 and is used to discharge non-condensable gas in the condensed water when opened.

[0121] A first pipeline L1 and a second pipeline L2 are arranged in parallel between the third inlet 21 of the second heat exchanger 2 and the sixth outlet 34 of the third heat exchanger 3 , and a gas-liquid separator 5 ′ is arranged in the second pipeline L2 .

[0122] Optionally, the sewage treatment system also includes: a sediment container 9 and a sludge drying container 10, the bottom of the first heat exchanger 1 has a sediment outlet 15, the sediment container 9 has a seventh inlet 91, a seventh outlet 92 and a water inlet 93, the seventh inlet 91 is connected to the sediment outlet 15, the sludge drying container 10 is connected to the seventh outlet 92, and the water inlet 93 is connected to the fifth pipeline L5 through the fourth pipeline L4.

[0123] The sewage treatment part is provided with multiple valves. For example, a liquid level detection component 5 is provided on the first pipeline L1, and a first on-off valve 71 and a second on-off valve 72 are respectively provided on both sides of the liquid level detection component 5 on the first pipeline L1; a fourth on-off valve 74 is provided on the pipeline between the slag outlet 15 and the seventh inlet 91; a fifth on-off valve 75 is provided on the pipeline between the seventh outlet 92 and the sludge drying container 10; a sixth on-off valve 76 is provided on the fifth pipeline L5; an eighth on-off valve 78 is provided on the third pipeline L3, and a third on-off valve 73 is provided on the sixth pipeline L6.

[0124] The working principle of this sewage treatment device is:

[0125] The second heat exchanger 2 is used to preheat the sewage to be treated. The preheated sewage enters the first heat exchanger 1 through the ninth pipeline L9 and the second inlet 13, and exchanges heat with the high-temperature gaseous refrigerant entering the first heat exchanger 1 through the first inlet 11. Both the sewage and the gaseous refrigerant undergo phase change. The gaseous refrigerant condenses and exchanges heat to form liquid refrigerant, and is discharged through the first outlet 12 for refrigerant circulation. The sewage absorbs the heat released by the condensation of the gaseous refrigerant to perform evaporation heat exchange to form water vapor and is discharged through the second outlet 14.

[0126] The water vapor enters the third heat exchanger 3 through the eighth pipeline L8 and the sixth inlet 33, and the liquid refrigerant enters the third heat exchanger 3 through the sixth pipeline L6 and the fifth inlet 31, and the water vapor exchanges heat with the liquid refrigerant. After the liquid refrigerant evaporates and exchanges heat, it forms a low-temperature and low-pressure gaseous refrigerant, and enters the air inlet 41 of the compressor 4 for compression. After compression, the high-temperature and high-pressure gaseous refrigerant is discharged from the exhaust port 42 of the compressor 4, and returns to the first heat exchanger 1 through the seventh pipeline L7 and the first inlet 11, thereby the sixth pipeline L6 and the seventh pipeline L7 form a refrigerant circulation loop. At the same time, the water vapor undergoes condensation and heat exchange to form condensed water, and enters the second heat exchanger 2 through the second pipeline L2 and the third inlet 21.

[0127] At the same time, the sewage to be treated also enters the second heat exchanger 2 through the fifth pipeline L5 and the fourth inlet 23, and is preheated by condensed water. The preheated sewage is discharged through the fourth outlet 24 and enters the first heat exchanger 1 through the ninth pipeline L9 and the second inlet 13. After heat exchange, the condensed water is discharged through the third outlet 22 and enters the third pipeline L3 for export, so as to realize sewage recovery.

[0128] Secondly, the present disclosure provides a recycling method based on the sewage recycling system of the above embodiment, which in some embodiments includes:

[0129] The sewage to be recycled is heat-exchanged with the condensed water recovered from the sewage by the second heat exchanger 2, so as to preheat the sewage to be recycled and discharge the condensed water after heat exchange;

[0130] The preheated sewage is heat-exchanged with the gaseous refrigerant through the first heat exchanger 1, so that the gaseous refrigerant is condensed and heat-exchanged to form liquid refrigerant, and the sewage is evaporated and heat-exchanged to form water vapor to form condensed water and enter the second heat exchanger 2.

[0131] This embodiment sets a second heat exchanger 2, and exchanges heat between the condensed water obtained after the sewage is evaporated and recovered and the sewage to be treated, so that the latent heat after the sewage is evaporated and recovered can be fully utilized in the sewage to be recovered, so as to increase the temperature of the sewage to be treated, thereby accelerating the evaporation of the sewage in the first heat exchanger 1 to form water vapor, which can improve the sewage treatment efficiency, increase the operating efficiency of the sewage recovery system, and reduce the energy consumption of the device operation.

[0132] In some embodiments, the recycling method of the present application further comprises:

[0133] The liquid refrigerant and water vapor are heat exchanged through the third heat exchanger 3, so that the liquid refrigerant evaporates and exchanges heat to form a gaseous refrigerant, which enters the first heat exchanger 1 after being compressed by the compressor 4, and the water vapor is condensed and exchanged to form condensed water, which enters the second heat exchanger 2.

[0134] This embodiment sets a third heat exchanger 3 to condense water vapor to exchange heat to form condensed water, and at the same time uses the heat released during the condensation process to convert liquid refrigerant into gaseous refrigerant, thereby realizing the recycling of refrigerant and making full use of the heat released by the condensation of water vapor, greatly increasing the operating efficiency of the sewage recovery system and reducing the operating energy consumption.

[0135] In some embodiments, a first pipeline L1 and a second pipeline L2 are connected in parallel between the second heat exchanger 2 and the third heat exchanger 3, the first pipeline L1 is used to contain gas in condensed water, a gas-liquid separator 5' is provided on the second pipeline L2, a liquid level detection component 5 is provided on the first pipeline L1, and a first on-off valve 71 and a second on-off valve 72 are respectively provided on both sides of the liquid level detection component 5 on the first pipeline L1; the recovery method further includes:

[0136] During the sewage recovery process, the first on-off valve 71 and the second on-off valve 72 are both in an on state;

[0137] When the liquid level detection component 5 needs maintenance, both the first on-off valve 71 and the second on-off valve 72 are in the off state.

[0138] This embodiment can not only separate the non-condensable gas in the condensed water in time and keep the gas in the first pipeline L1, thereby preventing the gas from accumulating in the main pipeline to occupy volume and block the pipeline, and preventing the non-condensable gas from affecting the process of sewage evaporation to form water vapor, but also improve the flow efficiency of the liquid in the pipeline and improve the sewage recovery efficiency; moreover, when the first on-off valve 71 and the second on-off valve 72 are in the disconnected state, the first pipeline L1 can be independent of the second pipeline L2 without affecting the sewage treatment process.

[0139] In some embodiments, the wastewater recovery system further includes: a third pipeline L3 for extracting condensed water passing through the first heat exchanger 1; and a negative pressure pump 7, which is arranged on the third pipeline L3; the recovery method of the present disclosure further includes:

[0140] During the sewage recovery process, the operating frequency of the negative pressure pump 7 is adjusted according to the demand load of the condensed water and / or the amount of condensed water generated.

[0141] The amount of condensed water generated can be detected by a liquid level detection component 5 disposed in the first pipeline L1. The liquid level detection component 5 can detect the liquid level of the gas-liquid separator 5' to obtain the amount of condensed water stored inside the gas-liquid separator 5'.

[0142] This embodiment can increase the operating frequency of the negative pressure pump 7 to meet the condensate water supply demand when the external condensate water demand is large or the condensate water generated during the sewage recovery process is large; when the external condensate water demand is small or the condensate water generated during the sewage recovery process is small, reduce the operating frequency of the negative pressure pump 7 to reduce the operating energy consumption of the negative pressure pump 7 on the basis of meeting the condensate water supply demand.

[0143] In some embodiments, the first heat exchanger 1 further has a slag outlet 15, and the sewage recovery system further includes: a sludge container 9 having a seventh inlet 91 and a seventh outlet 92, the seventh inlet 91 being connected to the slag outlet 15; and a sludge drying container 10 being connected to the seventh outlet 92; wherein a fourth on-off valve 74 is provided on the pipeline between the slag outlet 15 and the seventh inlet 91, and a fifth on-off valve 75 is provided on the pipeline between the seventh outlet 92 and the sludge drying container 10; and the recovery method further includes:

[0144] During the sewage recovery process, the fourth on-off valve 74 is in an on state, and the fifth on-off valve 75 is in an off state;

[0145] During the slag discharge process, the fourth on-off valve 74 is in an off state, and the fifth on-off valve 75 is in an on state, so that the sludge in the sediment container 9 is discharged into the sludge drying container 10 .

[0146] This embodiment can allow the sludge at the bottom of the first heat exchanger 1 to enter the sediment container 9 during the sewage recovery process, and can maintain the negative pressure requirement of the system, so that the sewage recovery process proceeds smoothly; moreover, the sludge in the sediment container 9 enters the sludge drying container 10 for drying, and at the same time, the negative pressure in the system can still be maintained during the slag discharge process.

[0147] In some embodiments, the sediment container 9 has a water inlet 93, and the sewage recovery system further includes: a fourth pipeline L4, both ends of which are respectively connected to the fifth pipeline L5 and the water inlet 93, the fifth pipeline L5 is used to pass the sewage to be treated, and the fourth pipeline L4 is provided with a sixth on-off valve 76; the recovery method also includes:

[0148] After the slag discharge is completed, the sixth on-off valve 76 is turned on to allow water to flow into the sludge container 9 to remove the sludge;

[0149] After the preset flushing time, the fifth on-off valve 75 is in the off state, and water continues to flow into the sediment container 9, so that the sediment container 9 is filled with water;

[0150] After the water filling is completed, the fourth on-off valve 74 is in the on state, and the fifth on-off valve 75 and the sixth on-off valve 76 are in the off state.

[0151] This embodiment can open the sixth on-off valve 76 to introduce sewage to be treated after the sludge in the sediment container 9 is discharged into the sludge drying container 10, so as to flush the sediment container 9, remove the sludge in time, and prevent the sludge from accumulating in the sediment container 9. After the preset flushing time, the fifth on-off valve 75 is in the disconnected state, and water continues to be introduced into the sediment container 9 to fill the sediment container 9 with water, so that the sewage completely occupies the space in the sediment container 9. After the fourth on-off valve 74 is turned on in the subsequent sewage treatment process, the negative pressure value in the first heat exchanger 1 is kept unchanged, which is also convenient for sedimentation in the subsequent sewage treatment process. In addition, after the water filling is completed, the fifth on-off valve 75 and the sixth on-off valve 76 are in the disconnected state, and the fourth on-off valve 74 is in the connected state, so that the pressure in the system can be maintained to enter the sewage recovery process at any time.

[0152] Each on-off valve and heat exchanger in the above embodiments of the present disclosure can be controlled by a controller, which can be a general-purpose processor, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components or any appropriate combination thereof for performing the functions described in the present disclosure.

[0153] The above description is only an exemplary embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A sewage recovery system, characterized in that: include: The first heat exchanger (1) has a first inlet (11), a first outlet (12), a second inlet (13), a second outlet (14) and a slag outlet (15), wherein the first inlet (11) is used to introduce a gaseous refrigerant, and the first outlet (12) is connected to the first inlet (11) and is used to discharge liquid refrigerant formed after condensation heat exchange between the gaseous refrigerant and sewage; the second inlet (13) is used to introduce sewage, and the second outlet (14) is used to discharge water vapor formed after evaporation heat exchange between the sewage and the gaseous refrigerant; The second heat exchanger (2) has a third inlet (21), a third outlet (22), a fourth inlet (23) and a fourth outlet (24), wherein the third inlet (21) is used to introduce condensed water formed by water vapor, and the third outlet (22) is connected to the third inlet (21) and is used to discharge the condensed water after heat exchange with the wastewater to be recycled; the fourth inlet (23) is used to introduce wastewater to be recycled, and the fourth outlet (24) is connected to both the fourth inlet (23) and the second inlet (13) and is used to allow the wastewater after heat exchange with the condensed water to enter the first heat exchanger (1); A sediment container (9) having a seventh inlet (91), a seventh outlet (92) and a water inlet (93), wherein the seventh inlet (91) is connected to the sediment outlet (15); A sludge drying container (10) connected to the seventh outlet (92); a fourth on-off valve (74) provided on the pipeline between the slag outlet (15) and the seventh inlet (91); a fifth on-off valve (75) provided on the pipeline between the seventh outlet (92) and the sludge drying container (10); and a fourth pipeline (L4), the two ends of which are respectively connected to the fifth pipeline (L5) and the water inlet (93); the fifth pipeline (L5) is used to introduce the sewage to be treated; the fourth pipeline (L4) is provided with a sixth on-off valve (76) so as to allow water to enter the sediment container (9) when the sixth on-off valve (76) is in an on state; In the process of sewage recovery, the fourth on-off valve (74) is in an on state, and the fifth on-off valve (75) is in an off state, so as to maintain the negative pressure requirement of the system and keep the pressure in the first heat exchanger (1) constant; in the process of slag discharge, the fourth on-off valve (74) is in an off state, and the fifth on-off valve (75) is in an on state, so as to discharge the sludge in the sediment container (9) into the sludge drying container (10), and maintain the negative pressure in the system; After the slag discharge is completed, the sixth on-off valve (76) is in an on state, and the fifth on-off valve (75) is configured to be in an off state after a preset flushing time, so as to continue to feed water into the slag container (9), so that the slag container (9) is filled with sewage to be treated; After the water filling is completed, the fifth on-off valve (75) and the sixth on-off valve (76) are in an off state, and the fourth on-off valve (74) is in an on state, so as to maintain the system pressure for sewage recovery.

2. The sewage recovery system according to claim 1, characterized in that: Also includes: Compressor (4); and The third heat exchanger (3) has a fifth inlet (31), a fifth outlet (32), a sixth inlet (33) and a sixth outlet (34); the fifth inlet (31) is connected to the first outlet (12); the fifth outlet (32) is connected to the first inlet (11) through the compressor (4); the sixth inlet (33) is connected to the second outlet (14); the sixth outlet (34) is connected to the sixth inlet (33) and the third inlet (21); the third heat exchanger (3) is used to perform heat exchange between liquid refrigerant and water vapor to achieve phase change.

3. The sewage recovery system according to claim 2, characterized in that: Also includes: A first pipeline (L1) and a second pipeline (L2) are connected in parallel, and the first ends of the first pipeline (L1) and the second pipeline (L2) are respectively connected to the sixth outlet (34), and the second ends of the first pipeline (L1) and the second pipeline (L2) are respectively connected to the third inlet (21), the first pipeline (L1) is used to contain the gas in the condensed water, and the second pipeline (L2) is provided with a gas-liquid separator (5').

4. The sewage recovery system according to claim 3, characterized in that: Also includes: A liquid level detection component (5), arranged in the first pipeline (L1), and used to detect the liquid level of condensed water in the first pipeline (L1); and The first on-off valve (71) and the second on-off valve (72) are arranged on the first pipeline (L1) and are respectively located on both sides of the liquid level detection component (5).

5. The sewage recovery system according to claim 3, characterized in that: Also includes: a third pipeline (L3), connected to the third outlet (22), for conducting the condensed water; A negative pressure pump (7) is arranged on the third pipeline (L3); and An exhaust valve (8) is provided on the third pipeline (L3) and is located at the inlet of the negative pressure pump (7), and the exhaust valve (8) is connected to the first pipeline (L1) and is used to exhaust the gas in the condensed water in an open state.

6. The sewage recovery system according to claim 5, characterized in that: It also includes a connecting pipe, through which the exhaust valve (8) and the first pipeline (L1) are connected.

7. The sewage recovery system according to claim 1, characterized in that: Also includes: a third pipeline (L3), connected to the third outlet (22), for conducting the condensed water; and A negative pressure pump (7) is provided on the third pipeline (L3) and is used to maintain a negative pressure in the first heat exchanger (1).

8. The sewage recovery system according to claim 7, characterized in that: The negative pressure pump (7) is a variable frequency pump, and the operating frequency is configured to be adjusted according to the demand for condensed water and / or the amount of condensed water generated.

9. The sewage recovery system according to claim 1, characterized in that: Also includes: a third pipeline (L3), connected to the third outlet (22), for conducting the condensed water; and A one-way valve (6) is provided on the third pipeline (L3) and is used to allow only the condensed water to flow in one direction along the third pipeline (L3) from the third outlet (22).

10. A recycling method based on the sewage recycling system according to any one of claims 1 to 9, characterized in that: include: The sewage to be recovered is heat exchanged with condensed water recovered from the sewage by the second heat exchanger (2) to preheat the sewage to be recovered, and the condensed water is discharged after heat exchange; The preheated sewage is subjected to heat exchange with the gaseous refrigerant through the first heat exchanger (1), so that the gaseous refrigerant is condensed and heat-exchanged to form liquid refrigerant, and the sewage is evaporated and heat-exchanged to form water vapor, which then enters the second heat exchanger (2) after forming condensed water; During the sewage recovery process, the fourth on-off valve (74) is in an on state, and the fifth on-off valve (75) is in an off state; During the slag discharge process, the fourth on-off valve (74) is in an off state, and the fifth on-off valve (75) is in an on state, so that the sludge in the sediment container (9) is discharged into the sludge drying container (10); After the slag discharge is completed, the sixth on-off valve (76) is turned on to allow water to flow into the sludge container (9) to remove sludge; After the preset flushing time, the fifth on-off valve (75) is placed in an off state, and water continues to flow into the sediment container (9) so that the sediment container (9) is filled with water; After the water filling is completed, the fourth on-off valve (74) is in an on state, and the fifth on-off valve (75) and the sixth on-off valve (76) are in an off state.

11. The recycling method according to claim 10, characterized in that: The recycling method further comprises: The liquid refrigerant and water vapor are heat exchanged through the third heat exchanger (3), so that the liquid refrigerant evaporates and exchanges heat to form a gaseous refrigerant, which enters the first heat exchanger (1) after being compressed by the compressor (4), and the water vapor is condensed and exchanges heat to form condensed water, which enters the second heat exchanger (2).

12. The recycling method according to claim 11, characterized in that: A first pipeline (L1) and a second pipeline (L2) are provided in parallel between the second heat exchanger (2) and the third heat exchanger (3); the first pipeline (L1) is used to contain the gas in the condensed water; the second pipeline (L2) is provided with a gas-liquid separator (5'); the first pipeline (L1) is provided with a liquid level detection component (5); and the first pipeline (L1) is provided with a first on-off valve (71) and a second on-off valve (72) on both sides of the liquid level detection component (5); the recovery method further comprises: During the sewage recovery process, the first on-off valve (71) and the second on-off valve (72) are both in an on state; When the liquid level detection component (5) needs maintenance, both the first on-off valve (71) and the second on-off valve (72) are placed in an off state.

13. The recycling method according to claim 10, characterized in that: The wastewater recovery system further comprises: a third pipeline (L3) for conducting away the condensed water passing through the first heat exchanger (1); and a negative pressure pump (7) provided on the third pipeline (L3); and the recovery method further comprises: During the sewage recovery process, the operating frequency of the negative pressure pump (7) is adjusted according to the demand load of condensed water and / or the amount of condensed water generated.

Images