Multiple-effect desalination system

Abstract

The application provides a multi-effect desalination system and relates to the technical field of multi-effect evaporation. The multi-effect desalination system can have two working conditions under the action of a first valve, a second valve and a third valve. The first working condition is that the third valve is closed, and the first valve and the second valve are opened. At this time, low-pressure steam discharged by a low-pressure steam generation device is directly introduced into a first-effect evaporator as heating steam. A second condenser can condense part of secondary steam generated by an mth-effect evaporator, so that the pressure in the first condenser and the second condenser is balanced, and the two can work under normal working conditions. The second working condition is that the second valve is opened, the first valve and the third valve are closed, and the second condenser stops working. Medium-pressure steam discharged from a medium-pressure steam generation device is introduced into the mth-effect evaporator to inject the secondary steam generated by the mth-effect evaporator through a steam heat compressor. After mixing, the medium-pressure steam is introduced into the first-effect evaporator as heating steam, so that the energy of the medium-pressure steam can be effectively utilized, and a higher water production ratio is obtained.

Description

Technical Field

[0001] This invention relates to the field of multi-effect evaporation technology, and more specifically to a multi-effect desalination system. Background Technology

[0002] Thermal desalination technologies, such as low-temperature multi-effect distillation (MED), are widely used in seawater desalination, high-mineralization mine water desalination, and various wastewater desalination and wastewater reduction treatment. Because this technology operates at low temperatures—typically below 75°C—it reduces the risk of scaling and corrosion. Furthermore, it utilizes inexpensive low-temperature steam to drive water production, thus providing a relatively economical way to obtain high-quality distilled freshwater.

[0003] Depending on the quality (pressure, temperature) of the heating steam, low-temperature multi-effect distillation typically operates in two modes: 1. Steam thermal compression, i.e., MED-TVC mode; 2. Direct steam heating, i.e., pure MED mode. For example, in thermal seawater desalination combined with power plants, steam extracted from the turbine is used as the heat source, and the first mode is often adopted. That is, the low-pressure steam extracted from the turbine first drives the TVC, and the secondary steam generated by the evaporation of some seawater is mixed and then enters the first effect of the low-temperature multi-effect evaporator as heating steam to obtain a better water production ratio and water production economy. In the chemical and metallurgical fields, where low-temperature waste heat steam or low-temperature steam generated by hot water flash evaporation is used as the heat source, since the steam parameters are low and close to the inlet steam parameters required for the first effect, the direct steam heating method is often adopted. Usually, the heating steam is sprayed with water to remove superheat and then directly introduced into the first effect evaporator to produce water.

[0004] The two operating modes require different steam pressure ranges. Generally, the steam pressure range required for the steam thermal compression operating mode is greater than that required for the direct steam heating mode. Traditional technical solutions can only adapt to one operating mode under one steam pressure range, resulting in poor compatibility of the multi-effect desalination system, reduced water production efficiency, and increased operating costs. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-effect desalination system to solve the problem that existing multi-effect desalination systems cannot be compatible with multiple steam pressure ranges.

[0006] To achieve the above objectives, embodiments of the present invention provide a multi-effect desalination system, comprising:

[0007] A multi-effect evaporator includes multiple evaporators connected in series, wherein the heat exchange area of ​​the first to m-1th effects evaporators is greater than the heat exchange area of ​​the m to nth effects evaporators.

[0008] The first condenser system has its steam inlet connected to the exhaust end of the nth effect evaporator in the multi-effect evaporator, and its distilled water discharge end connected to the distilled water inlet of the nth effect evaporator in the multi-effect evaporator.

[0009] The second condenser system has its vacuum end connected to the steam inlet of the first condenser system and the exhaust end of the nth effect evaporator in the multi-effect evaporator. The distilled water discharge end of the second condenser system is connected to the distilled water inlet of the mth effect evaporator in the multi-effect evaporator. The steam inlet of the second condenser system is connected to the exhaust end of the (m-1)th effect evaporator in the multi-effect evaporator. A first valve is installed between the steam inlet of the second condenser system and the exhaust end of the (m-1)th effect evaporator in the multi-effect evaporator.

[0010] The medium-pressure steam conveying system includes a medium-pressure steam generating device, a steam thermal compressor, and a steam jet vacuum device. The output end of the medium-pressure steam generating device is connected to the power steam input end of the steam thermal compressor and the power steam input end of the steam jet vacuum device. The ejector end of the steam jet vacuum device is connected to the vacuum end of the first condenser system. The cooling water input end of the steam jet vacuum device is connected to the material water end of the second to nth effects of the multi-effect evaporator and the material water discharge end of the first condenser system. The cooling water output end of the steam jet vacuum device is connected to the material water end of the first effect of the multi-effect evaporator. The steam condensate output end of the steam jet vacuum device is connected to the fresh water input end of the first effect of the multi-effect evaporator. The ejector end of the steam thermal compressor is connected to the exhaust end of the (m-1)th effect of the multi-effect evaporator. The steam output end of the steam thermal compressor is connected to the steam inlet end of the first effect of the multi-effect evaporator. A second valve is provided between the steam output end of the steam thermal compressor and the steam inlet end of the first effect of the multi-effect evaporator.

[0011] The low-pressure steam conveying system includes a low-pressure exhaust steam generating device. The exhaust end of the low-pressure exhaust steam generating device is connected to the heating steam inlet end of the first-effect evaporator in the multi-effect evaporator. A third valve is provided between the exhaust end of the low-pressure exhaust steam generating device and the heating steam inlet end of the first-effect evaporator in the multi-effect evaporator.

[0012] Optionally, the first condenser system includes: a first condenser, a first condenser inlet steam line, and a first condenser distilled water outlet line;

[0013] The steam inlet of the first condenser is connected to the exhaust end of the nth effect evaporator in the multi-effect evaporator through the steam inlet pipe of the first condenser, and the distilled water discharge end of the first condenser is connected to the distilled water inlet of the nth effect evaporator in the multi-effect evaporator through the distilled water discharge pipe of the first condenser.

[0014] Optionally, the second condenser system includes: a second condenser, a second condenser vacuum line, a second condenser steam inlet line, and a second condenser distilled water outlet line;

[0015] The vacuum end of the second condenser is connected to the steam inlet of the first condenser through the vacuum pipeline of the second condenser. The distilled water discharge end of the second condenser is connected to the distilled water inlet of the m-th effect evaporator through the distilled water discharge pipeline of the second condenser. The steam inlet of the second condenser is connected to the exhaust end of the m-th effect evaporator in the multi-effect evaporator through the steam inlet pipeline of the second condenser. A first valve is provided on the steam inlet pipeline of the second condenser. A flow regulating component is provided on the vacuum pipeline of the second condenser. A water pump is provided on the distilled water discharge pipeline of the second condenser.

[0016] Optionally, the medium-pressure steam conveying system includes: a steam input pipeline for a steam thermal compressor, an ejector pipeline for a steam thermal compressor, an output pipeline for a steam thermal compressor, a steam input pipeline for a steam jet vacuum equipment, a vacuuming pipeline for a steam jet vacuum equipment, a material water pipeline, and a condensate output pipeline.

[0017] The output end of the medium-pressure steam generator is connected to the power steam input end of the steam jet vacuum equipment via the power steam input pipeline. The ejector end of the steam jet vacuum equipment is connected to the vacuum end of the first condenser via the vacuum pipeline. The cooling water input end of the steam jet vacuum equipment is connected to the material water end of the second to nth effects evaporators in the multi-effect evaporator and the material water discharge end of the first condenser via the material water pipeline. The cooling water output end of the steam jet vacuum equipment is connected to the material water end of the first effect evaporator in the multi-effect evaporator. The steam condensate of the steam jet vacuum equipment... The output end is connected to the material water end of the first effect evaporator of the multi-effect evaporator through the condensate output pipeline. The power steam input end of the steam thermal compressor is connected to the power steam input pipeline of the steam jet vacuum equipment through the power steam input pipeline of the steam thermal compressor. The ejector end of the steam thermal compressor is connected to the steam inlet pipeline of the second condenser through the ejector pipeline of the steam thermal compressor. The steam output end of the steam thermal compressor is connected to the steam inlet end of the first effect evaporator in the multi-stage evaporator through the steam thermal compressor output pipeline. A second valve is installed on the output pipeline of the steam thermal compressor, and a water pump is installed on the material water pipeline.

[0018] Optionally, the low-pressure steam delivery system includes: a low-pressure waste steam generating device and a low-pressure steam pipeline. The output end of the low-pressure waste steam generating device is connected to the heating steam inlet of the first-effect evaporator in the multi-stage evaporator through the low-pressure steam pipeline. A third valve is provided on the low-pressure steam pipeline.

[0019] Optionally, the first condenser system further includes: a seawater production device, a seawater discharge pipeline, and a cooling seawater discharge system. One end of the seawater discharge pipeline is connected to the output end of the seawater production device, and the other end of the seawater discharge pipeline is connected to the input end of the cooling seawater discharge system after passing through the first condenser.

[0020] Optionally, the first condenser system also includes: a brine cooler, a brine discharge device, a brine discharge pipeline, and a first seawater discharge bypass;

[0021] One end of the brine discharge pipeline is connected to the brine discharge end of the nth effect evaporator in the multi-effect evaporator, and the other end of the brine discharge pipeline is connected to the brine discharge device after passing through the brine cooler. One end of the first seawater discharge bypass is connected to the seawater discharge pipeline, and the other end of the first seawater discharge bypass is connected to the seawater discharge pipeline after passing through the brine cooler.

[0022] Optionally, the first condenser system also includes: a distilled water cooler, a distilled water collection device, a distilled water discharge pipeline, and a second seawater discharge bypass;

[0023] One end of the distilled water discharge pipeline is connected to the distilled water discharge end of the nth effect evaporator in the multi-effect evaporator, and the other end of the distilled water discharge pipeline is connected to the distilled water collection device via the distilled water cooler. One end of the second seawater discharge bypass is connected to the seawater discharge pipeline, and the other end of the second seawater discharge bypass is connected to the seawater discharge pipeline via the distilled water cooler.

[0024] Optionally, the system further includes: a desuperheating water pipeline, a low-pressure steam input bypass, a condensate collection pipeline, and a condensate collection tank;

[0025] In a multi-effect evaporator, the condensate discharge end of the first-effect evaporator is connected to the power steam input pipeline of the steam jet vacuum equipment via a desuperheating water pipeline. The low-pressure steam pipeline is connected to the desuperheating water pipeline via a low-pressure steam input bypass. The condensate collection tank is connected to the desuperheating water pipeline via a condensate collection pipeline.

[0026] Optionally, a low-pressure steam desuperheater is installed on the low-pressure steam pipeline; a water spray desuperheater is installed on the power steam input pipeline of the steam jet vacuum equipment.

[0027] In this embodiment of the invention, under the action of the first valve, the second valve, and the third valve, there are two operating conditions. The first condition is that the third valve is closed, and the first and second valves are open. In this case, the low-pressure steam discharged from the low-pressure exhaust steam generator is directly fed into the first-effect evaporator as heating steam. The second condenser can condense a portion of the secondary steam generated by the m-th effect evaporator, balancing the pressure in the first and second condensers, allowing them to operate under normal conditions. The second condition is that the second valve is open, and the first and third valves are closed. The second condenser stops working, and the medium-pressure steam discharged from the medium-pressure steam generator is induced by a steam thermal compressor to inject the secondary steam generated by the m-th effect evaporator. After mixing, it is fed into the first-effect evaporator as heating steam, thereby effectively utilizing the energy of the medium-pressure steam to achieve a higher water production ratio.

[0028] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a multi-effect desalination system provided in one embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a multi-effect desalination system provided in another embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of a multi-effect desalination system provided in another embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Evaporators with effects m to n; 2. Evaporators with effects 1 to m-1;

[0034] 3. First condenser; 4. Second condenser; 5. First valve;

[0035] 6. Medium-pressure steam generating unit; 7. Steam thermal compressor;

[0036] 8. Vacuum jetting equipment; 9. Second valve; 10. Low-pressure exhaust steam generator;

[0037] 11. Third valve; 12. Steam inlet pipeline of the first condenser;

[0038] 13. First condenser distilled water discharge pipeline; 14. Second condenser steam inlet pipeline;

[0039] 15. Vacuum pumping pipeline for the second condenser; 16. Distilled water discharge pipeline for the second condenser;

[0040] 17. Steam input pipeline for the steam thermal compressor; 18. Ejector pipeline for the steam thermal compressor;

[0041] 19. Steam compressor output pipeline; 20. Steam injection pipeline for steam jet vacuum equipment;

[0042] 21. Vacuuming pipeline of vapor jet vacuum equipment; 22. Material water pipeline;

[0043] 23. Condensate output pipeline; 24. Low-pressure steam pipeline; 25. Seawater production unit;

[0044] 26. Seawater discharge pipeline; 27. Cooling seawater discharge system; 28. Brine discharge device;

[0045] 29. Brine discharge pipeline; 30. Brine cooler; 31. First bypass for seawater discharge;

[0046] 32. Distilled water collection device; 33. Distilled water cooler; 34. Distilled water discharge pipeline;

[0047] 35. Second bypass for seawater discharge; 36. Condensate collection tank; 37. Desuperheating water pipeline;

[0048] 38. Condensate collection pipeline; 39. Low-pressure steam input bypass; 40. Low-pressure steam desuperheater;

[0049] 41. Water spray desuperheater; 42. Flow regulation component; 43. Water pump.

[0050] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0052] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0053] Reference Figure 1This invention provides a multi-effect desalination system, comprising: a multi-effect evaporator, including multiple evaporators connected in series, wherein the heat exchange area of ​​the first to m-1 effect evaporators 2 is larger than the heat exchange area of ​​the m to n effect evaporators 1; a first condenser system, wherein the steam inlet of the first condenser system is connected to the exhaust end of the nth effect evaporator 1 in the multi-effect evaporator, and the distilled water discharge end of the first condenser system is connected to the distilled water inlet end of the nth effect evaporator 1 in the multi-effect evaporator; and a second condenser system, wherein the vacuum end of the second condenser system is connected to the steam inlet of the first condenser system and the nth effect evaporator 1 in the multi-effect evaporator. The exhaust end of condenser 1 is connected to the steam outlet of the second condenser system. The distilled water discharge end of the second condenser system is connected to the distilled water inlet of the m-th effect evaporator 1 in the multi-effect evaporator. The steam inlet of the second condenser system is connected to the exhaust end of the (m-1)-th effect evaporator 1 in the multi-effect evaporator. A first valve 5 is installed between the steam inlet of the second condenser system and the exhaust end of the (m-1)-th effect evaporator 1 in the multi-effect evaporator. The medium-pressure steam conveying system includes a medium-pressure steam generating device 6, a steam thermal compressor 7, and a steam jet vacuum device 8. The output end of the medium-pressure steam generating device 6 is connected to the power steam input end of the steam thermal compressor 7 and the steam jet vacuum device 8, respectively. The steam input terminal of the steam jet vacuum device 8 is connected to the steam injection vacuum device 8; the ejector terminal of the steam jet vacuum device 8 is connected to the vacuum terminal of the first condenser system; the cooling water input terminal of the steam jet vacuum device 8 is connected to the material water terminal of the second to nth effects evaporators in the multi-effect evaporator and the material water discharge terminal of the first condenser system; the cooling water output terminal of the steam jet vacuum device 8 is connected to the material water terminal of the first effect evaporator 2 in the multi-effect evaporator; the steam condensate output terminal of the steam jet vacuum device 8 is connected to the fresh water input terminal of the first effect evaporator 2 in the multi-effect evaporator; and the ejector terminal of the steam thermal compressor 7 is connected to the (m-1)th effect evaporator in the multi-effect evaporator. The exhaust end of device 1 is connected to the steam output end of the steam thermal compressor 7 and the steam inlet end of the first-effect evaporator 2 in the multi-effect evaporator. A second valve 9 is provided between the steam output end of the steam thermal compressor 7 and the steam inlet end of the first-effect evaporator 2 in the multi-effect evaporator. The low-pressure steam conveying system includes a low-pressure exhaust steam generating device 10. The exhaust end of the low-pressure exhaust steam generating device 10 is connected to the heating steam inlet end of the first-effect evaporator 2 in the multi-effect evaporator. A third valve 11 is provided between the exhaust end of the low-pressure exhaust steam generating device 10 and the heating steam inlet end of the first-effect evaporator 2 in the multi-effect evaporator.

[0054] In one embodiment, the first condenser system includes: a first condenser 3, a first condenser steam inlet pipe 12, and a first condenser distilled water outlet pipe 13; the steam inlet of the first condenser 3 is connected to the exhaust end of the nth effect evaporator 1 in the multi-effect evaporator through the first condenser steam inlet pipe 12, and the distilled water outlet of the first condenser 3 is connected to the distilled water inlet of the nth effect evaporator 1 in the multi-effect evaporator through the first condenser distilled water outlet pipe 13.

[0055] In one embodiment, the second condenser system includes: a second condenser 4, a second condenser vacuum line 15, a second condenser steam inlet line 14, and a second condenser distilled water outlet line 16; the vacuum end of the second condenser 4 is connected to the first condenser steam inlet line 12 through the second condenser vacuum line 15, the distilled water outlet of the second condenser 4 is connected to the distilled water inlet of the m-th effect evaporator 1 through the second condenser distilled water outlet line 16, the steam inlet of the second condenser 4 is connected to the exhaust end of the m-th effect evaporator 1 in the multi-effect evaporator through the second condenser steam inlet line 14, a first valve 5 is provided on the second condenser steam inlet line 14, a flow regulating component 42 is provided on the second condenser vacuum line 15, and a water pump 43 is provided on the second condenser distilled water outlet line 16.

[0056] In one embodiment, the medium-pressure steam conveying system includes: a steam input pipeline 17 for a steam thermal compressor, an ejector pipeline 18 for a steam thermal compressor, an output pipeline 19 for a steam thermal compressor, a steam input pipeline 20 for a steam jet vacuum device, a vacuuming pipeline 21 for a steam jet vacuum device, a material water pipeline 22, and a condensate output pipeline 23. The output end of the medium-pressure steam generating device 6 is connected to the steam input end of the steam jet vacuum device 8 via the steam input pipeline 20. The ejector end of the steam jet vacuum device 8 is connected to the vacuuming end of the first condenser via the vacuuming pipeline 21. The cooling water input end of the steam jet vacuum device 8 is connected to the material water end of the second to nth effects evaporators in the multi-effect evaporator and the material water discharge end of the first condenser 8 via the material water pipeline 22. The cooling water output end of the steam jet vacuum device 8 is connected to the material water end of the first-effect evaporator 2 of the multi-effect evaporator. The steam condensate output end of the steam jet vacuum device 8 is connected to the material water end of the first-effect evaporator 2 of the multi-effect evaporator through the condensate output pipe 23. The power steam input end of the steam thermal compressor 7 is connected to the power steam input pipe 20 of the steam jet vacuum device through the power steam input pipe 17 of the steam thermal compressor. The ejector end of the steam thermal compressor 7 is connected to the steam inlet pipe 14 of the second condenser through the steam ejector pipe 18 of the steam thermal compressor. The steam output end of the steam thermal compressor 7 is connected to the steam inlet end of the first-effect evaporator 2 in the multi-stage evaporator through the steam thermal compressor output pipe 19. A second valve 9 is installed on the steam thermal compressor output pipe 19. A water pump 43 is installed on the material water pipe 22.

[0057] In one embodiment, the low-pressure steam delivery system includes a low-pressure waste steam generating device 10 and a low-pressure steam pipeline 24. The output end of the low-pressure waste steam generating device 10 is connected to the heating steam inlet of the first-effect evaporator 2 in the multi-stage evaporator through the low-pressure steam pipeline 24. A third valve 11 is provided on the low-pressure steam pipeline 24.

[0058] A multi-effect evaporator is a series heat exchanger, with each independent condensation-evaporation heat exchanger unit called an effect. Heating steam enters the first-effect evaporator and condenses, releasing heat in the heat exchange tubes. This condensation heats the saline material water outside the tubes, causing the water to evaporate and produce steam. This steam is called the secondary steam of this effect. The secondary steam from the first effect then becomes the heating steam for the next effect, repeating the steam condensation-material water evaporation process until the last effect, i.e., the nth effect. Besides the condensate from the first effect being drawn off separately, starting from the second effect, distilled water flows by gravity through each effect under the pressure difference, collecting at the nth effect and being discharged as product desalinated water. The concentrated water remaining after the material water evaporates in the first effect is called brine, which flows by gravity through each effect to the nth effect and is discharged as concentrated brine.

[0059] The vapor ejection vacuum device 8 is used to remove non-condensable gases dissolved in the material water and air leaked into the multi-effect evaporator, so as to ensure that the multi-effect evaporation system can establish a normal temperature and pressure gradient and maintain the multi-effect evaporation process.

[0060] The power steam inlet line 17 and the low-pressure steam line 24 of the steam thermal compressor are used to supply heating steam to the first-effect evaporator in the multi-effect evaporator. The steam pressures supplied in the power steam inlet line 17 and the low-pressure steam line 24 are different. For example, the steam pressure range in the power steam inlet line 17 can be 3-7 bar, while the steam pressure range in the low-pressure steam line 24 is 0.3-1 bar.

[0061] The power steam input pipeline 17 of the steam thermal compressor introduces the secondary steam generated by the evaporation of seawater in the m-th effect evaporator of the multi-effect evaporator into the steam thermal compressor 7, where it is mixed, thereby improving energy utilization efficiency.

[0062] The second condenser 4 is used to condense the secondary steam generated by the first to m-1 effects of the multi-effect evaporator, and the first condenser 3 is used to condense the secondary steam generated by the multi-effect evaporator.

[0063] The flow regulating component 42 is used to adjust the steam flow rate input from the second condenser 4 into the first condenser 3, so that the first condenser 3 can operate under appropriate conditions.

[0064] In one embodiment, the flow regulating component 42 includes a regulating valve or a throttling orifice plate.

[0065] In one embodiment, the first condenser system further includes: a seawater production device 25, a seawater discharge pipeline 26, and a cooling seawater discharge system 27. One end of the seawater discharge pipeline 26 is connected to the output end of the seawater production device 25, and the other end of the seawater discharge pipeline 26 is connected to the input end of the cooling seawater discharge system 27 after passing through the first condenser 3.

[0066] The seawater discharge pipe 26 is used to introduce seawater into each evaporator. When the seawater discharge pipe 26 passes through the cooling medium channel of the first condenser 3, it can be heated by the steam in the first condenser 3, thereby improving energy utilization efficiency.

[0067] In one embodiment, the first condenser system further includes: a brine cooler 30, a brine discharge device 28, a brine discharge pipeline 29, and a first seawater discharge bypass 31; one end of the brine discharge pipeline 29 is connected to the brine discharge end of the nth effect evaporator 1 in the multi-effect evaporator, and the other end of the brine discharge pipeline 29 is connected to the brine discharge device 28 after passing through the brine cooler 30; one end of the first seawater discharge bypass 31 is connected to the seawater discharge pipeline 26, and the other end of the first seawater discharge bypass 31 is connected to the seawater discharge pipeline 26 after passing through the brine cooler 30.

[0068] The brine discharged from the multi-effect evaporator has a certain temperature. The seawater introduced into the cooling medium channel exchanges heat with the brine in the high-temperature medium channel, which lowers the brine temperature and raises the seawater temperature, thereby improving energy utilization efficiency.

[0069] In one embodiment, the first condenser system further includes: a distilled water cooler 33, a distilled water collection device 32, a distilled water discharge line 34, and a second seawater discharge bypass 35; one end of the distilled water discharge line 34 is connected to the distilled water discharge end of the nth effect evaporator 1 in the multi-effect evaporator, and the other end of the distilled water discharge line 34 is connected to the distilled water collection device 32 via the distilled water cooler 33; one end of the second seawater discharge bypass 35 is connected to the seawater discharge line 26, and the other end of the second seawater discharge bypass 35 is connected to the seawater discharge line 26 via the distilled water cooler 33.

[0070] The distilled water discharged from the multi-effect evaporator has a certain temperature. The seawater introduced into the cooling medium channel exchanges heat with the distilled water in the high-temperature medium channel, which lowers the temperature of the distilled water and raises the temperature of the seawater, thereby improving energy utilization efficiency.

[0071] In one embodiment, the system further includes: a desuperheating water pipeline 37, a low-pressure steam input bypass 39, a condensate collection pipeline 38, and a condensate collection tank 36; the condensate discharge end of the first-effect evaporator 2 in the multi-effect evaporator is connected to the power steam input pipeline 20 of the steam jet vacuum equipment through the desuperheating water pipeline 37, the low-pressure steam pipeline 24 is connected to the desuperheating water pipeline 37 through the low-pressure steam input bypass 39, and the condensate collection tank 36 is connected to the desuperheating water pipeline 37 through the condensate collection pipeline 38.

[0072] In one embodiment, the evaporators in the multi-effect evaporator are all evaporators equipped with spray components.

[0073] Evaporators with spray components can be selected from existing products, and their specific structures will not be described in detail here.

[0074] Evaporators with spray components can complete a large amount of evaporation in a short time, improving water production efficiency and heating more evenly, thus improving product quality.

[0075] In one embodiment, a low-pressure steam desuperheater 40 is provided on the low-pressure steam pipeline 24; a water spray desuperheater 41 is provided on the power steam input pipeline 20 of the steam jet vacuum equipment.

[0076] In this embodiment of the invention, the multi-effect desalination system can operate under two conditions under the action of the first valve 5, the second valve 9, and the third valve 11. In the first condition, the second valve 4 is closed, and the first valve 5 and the third valve 11 are open. At this time, the low-pressure steam discharged from the low-pressure steam conveying device 10 is directly fed into the first-effect evaporator 1 as heating steam. The second condenser 4 can condense part of the secondary steam generated by the m-th effect evaporator 2, balancing the pressure in the first condenser 3 and the second condenser 4, allowing both to operate under normal conditions. In the second condition, the second valve 9 is open, and the first valve 5 and the third valve 11 are closed. The second condenser 4 stops working, and the medium-pressure steam discharged from the medium-pressure steam generating device 6 is injected by the steam thermal compressor 7 into the m-th effect evaporator 1. After mixing, the mixture is fed into the first-effect evaporator 1 as heating steam, thereby effectively utilizing the energy of the medium-pressure steam to achieve a higher water production ratio.

[0077] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0078] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A multiple-effect desalination system, characterized in that, Comprise: Multi-effect evaporator, including a plurality of evaporators in series, the heat exchange area of the first to m-1 evaporators (2) is larger than that of the m to n evaporators (1); The first condenser system, the steam inlet end of the first condenser system is communicated with the steam outlet end of the n evaporator (1) in the multi-effect evaporator, and the distilled water discharge end of the first condenser system is communicated with the distilled water inlet end of the n evaporator (1) in the multi-effect evaporator; The second condenser system, the vacuumizing end of the second condenser system is communicated with the steam inlet end of the first condenser system and the steam outlet end of the n evaporator (1) in the multi-stage evaporator, the distilled water discharge end of the second condenser system is communicated with the distilled water inlet end of the m evaporator (1) in the multi-effect evaporator, the steam inlet end of the second condenser system is communicated with the steam outlet end of the m-1 evaporator (1) in the multi-effect evaporator, and the first valve (5) is arranged between the steam inlet end of the second condenser system and the steam outlet end of the m-1 evaporator (1) in the multi-effect evaporator; The medium-pressure steam conveying system comprises a medium-pressure steam generating device (6), a steam heat compressor (7) and a steam jet vacuumizing equipment (8), the output ends of the medium-pressure steam generating device (6) are respectively communicated with the power steam input end of the steam heat compressor (7) and the power steam input end of the steam jet vacuumizing equipment (8), the jet end of the steam jet vacuumizing equipment (8) is communicated with the vacuumizing end of the first condenser system, the cooling water input end of the steam jet vacuumizing equipment (8) is communicated with the material water end of the second to n evaporators in the multi-effect evaporator and the material water discharge end of the first condenser system, the cooling water output end of the steam jet vacuumizing equipment (8) is communicated with the material water end of the first evaporator (2) in the multi-effect evaporator, the steam condensate water output end of the steam jet vacuumizing equipment (8) is communicated with the fresh water input end of the first evaporator (2) in the multi-effect evaporator, the jet end of the steam heat compressor (7) is communicated with the steam outlet end of the m-1 evaporator (1) in the multi-effect evaporator, the steam output end of the steam heat compressor (7) is communicated with the steam inlet end of the first evaporator (2) in the multi-effect evaporator, and the second valve (9) is arranged between the steam output end of the steam heat compressor (7) and the steam inlet end of the first evaporator (2) in the multi-effect evaporator; The low-pressure steam conveying system comprises a low-pressure waste steam generating device (10), the steam outlet end of the low-pressure waste steam generating device (10) is communicated with the heating steam inlet end of the first evaporator (2) in the multi-effect evaporator, and the third valve (11) is arranged between the steam outlet end of the low-pressure waste steam generating device (10) and the heating steam inlet end of the first evaporator (2) in the multi-effect evaporator.

2. The multiple-effect desalination system of claim 1, wherein, The first condenser system comprises a first condenser (3), a first condenser steam inlet pipeline (12) and a first condenser distilled water discharge pipeline (13). The steam inlet end of the first condenser (3) is communicated with the steam exhaust end of the nth evaporator (1) in the multi-effect evaporator through the first condenser steam inlet pipeline (12), and the distilled water discharge end of the first condenser (3) is communicated with the distilled water inlet end of the nth evaporator (1) in the multi-effect evaporator through the first condenser distilled water discharge pipeline (13).

3. The multiple-effect desalination system of claim 2, wherein, The second condenser system comprises a second condenser (4), a second condenser vacuum pipeline (15), a second condenser steam inlet pipeline (14) and a second condenser distilled water discharge pipeline (16); The vacuum discharge end of the second condenser (4) is communicated with the first condenser steam inlet pipeline (12) through the second condenser vacuum pipeline (15), the distilled water discharge end of the second condenser (4) is communicated with the distilled water inlet end of the mth evaporator (1) through the second condenser distilled water discharge pipeline (16), the steam inlet end of the second condenser (4) is communicated with the steam exhaust end of the mth evaporator (1) in the multi-effect evaporator through the second condenser steam inlet pipeline (14), the first valve (5) is arranged on the second condenser steam inlet pipeline (14), the flow regulating assembly (42) is arranged on the second condenser vacuum pipeline (15), and the water pump (43) is arranged on the second condenser distilled water discharge pipeline (16).

4. The multiple-effect desalination system of claim 3, wherein, The medium-pressure steam conveying system comprises a steam heat compressor power steam input pipeline (17), a steam heat compressor extraction pipeline (18), a steam heat compressor output pipeline (19), a steam jet vacuumizing equipment power steam input pipeline (20), a steam jet vacuumizing equipment vacuumizing pipeline (21), a material water pipeline (22) and a condensed water output pipeline (23). The output end of the medium-pressure steam generating device (6) is communicated with the power steam input end of the steam-jet vacuumizing device (8) through a steam-jet vacuumizing device power steam input pipeline (20), the injection end of the steam-jet vacuumizing device (8) is communicated with the vacuumizing end of the first condenser through a steam-jet vacuumizing device vacuumizing pipeline (21), the cooling water input end of the steam-jet vacuumizing device (8) is communicated with the material water end of the second to nth evaporators in the multi-effect evaporator and the material water discharge end of the first condenser (8) through a material water pipeline (22), the cooling water output end of the steam-jet vacuumizing device (8) is communicated with the material water end of the first evaporator (2) of the multi-effect evaporator, the steam condensate water output end of the steam-jet vacuumizing device (8) is communicated with the material water end of the first evaporator (2) of the multi-effect evaporator through a condensate water output pipeline (23), the power steam input end of the steam heat compressor (7) is communicated with the steam-jet vacuumizing device power steam input pipeline (20) through a steam heat compressor power steam input pipeline (17), the injection end of the steam heat compressor (7) is communicated with the second condenser steam inlet pipeline (14) through a steam heat compressor injection pipeline (18), the steam output end of the steam heat compressor (7) is communicated with the steam inlet end of the first evaporator (2) in the multi-stage evaporator through a steam heat compressor output pipeline (19), a second valve (9) is arranged on the steam heat compressor output pipeline (19), and a water pump (43) is arranged on the material water pipeline (22).

5. The multiple-effect desalination system of claim 4, wherein, The low-pressure steam conveying system comprises a low-pressure waste steam generating device (10) and a low-pressure steam pipeline (24), and the output end of the low-pressure waste steam generating device (10) is communicated with the heating steam inlet end of the first evaporator (2) in the multi-stage evaporator through the low-pressure steam pipeline (24), and a third valve (11) is arranged on the low-pressure steam pipeline (24).

6. The multiple-effect desalination system of claim 2, wherein, The first condenser system further comprises a seawater outlet device (25), a seawater discharge pipeline (26) and a cooling seawater discharge system (27), one end of the seawater discharge pipeline (26) is communicated with the output end of the seawater outlet device (25), and the other end of the seawater discharge pipeline (26) is communicated with the input end of the cooling seawater discharge system (27) after passing through the first condenser (3).

7. The multiple-effect desalination system of claim 6, wherein, The first condenser system further comprises a brine cooler (30), a brine discharge device (28), a brine discharge pipeline (29) and a seawater discharge first bypass (31); one end of the brine discharge pipeline (29) is communicated with the brine discharge end of the nth evaporator (1) in the multi-effect evaporator, the other end of the brine discharge pipeline (29) is communicated with the brine discharge device (28) after passing through the brine cooler (30), one end of the seawater discharge first bypass (31) is communicated with the seawater discharge pipeline (26), and the other end of the seawater discharge first bypass (31) is communicated with the seawater discharge pipeline (26) after passing through the brine cooler (30).

8. The multiple-effect desalination system of claim 6, wherein, The first condenser system further comprises a distilled water cooler (33), a distilled water collecting device (32), a distilled water discharge pipeline (34) and a seawater discharge second bypass (35); One end of the distilled water discharge pipeline (34) is communicated with the distilled water discharge end of the nth evaporator (1) in the multi-effect evaporator, the other end of the distilled water discharge pipeline (34) is communicated with the distilled water collecting device (32) through the distilled water cooler (33), one end of the seawater discharge second bypass (35) is communicated with the seawater discharge pipeline (26), the other end of the seawater discharge second bypass (35) is communicated with the seawater discharge pipeline (26) through the distilled water cooler (33).

9. The multiple-effect desalination system of claim 5, wherein, The system further comprises a desuperheating water pipeline (37), a low-pressure steam input bypass (39), a condensate collecting pipeline (38) and a condensate collecting tank (36); The condensate discharge end of the first evaporator (2) in the multi-effect evaporator is communicated with the jet-pumping vacuum equipment power steam input pipeline (20) through the desuperheating water pipeline (37), the low-pressure steam pipeline (24) is communicated with the desuperheating water pipeline (37) through the low-pressure steam input bypass (39), and the condensate collecting tank (36) is communicated with the desuperheating water pipeline (37) through the condensate collecting pipeline (38).

10. The multiple-effect desalination system of claim 5, wherein, The low-pressure steam pipeline (24) is provided with a low-pressure steam desuperheater (40), and the jet-pumping vacuum equipment power steam input pipeline (20) is provided with a water injection desuperheater (41). The low-pressure steam pipeline (24) is provided with a low-pressure steam desuperheater (40), and the jet-pumping vacuum equipment power steam input pipeline (20) is provided with a water injection desuperheater (41).

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