A system and method for increasing the water production ratio of thermal seawater desalination

Abstract

The application provides a system and method for improving water production ratio of thermal seawater desalination, wherein the system for improving water production ratio of thermal seawater desalination comprises a seawater pipeline, a cooling water pipeline and an energy-saving pipeline; the output end of the seawater pipeline is communicated with the input end of a multi-effect evaporation system to form a passage, and is respectively communicated with a falling film condenser, a concentrated brine feeding water heat exchanger and a product water heat exchanger; the input end and the output end of the cooling water pipeline are communicated with a cooling tower to form a loop, and are respectively communicated with an NCG condensate water heat exchanger, a forced circulation condenser and a cooling water side of a condensate water heat exchanger; the energy-saving pipeline comprises a first pipeline, a second pipeline, a third pipeline and a fourth pipeline. The system and method for improving water production ratio of thermal seawater desalination can increase the reliability and flexibility of the system, avoid the loss of heat and working medium, reduce the use amount of first-effect heat exchange steam and the operation and maintenance cost of a circulating cooling tower system, and improve the water production ratio.

Description

Technical Field

[0001] The present application relates to the field of thermal seawater desalination, and in particular to a system and method for improving the water production ratio of thermal seawater desalination. Background Art

[0002] Desalination refers to water treatment technologies that remove most of the salt from seawater, making the treated water suitable for use as drinking water or boiler feed water. Currently, the mainstream desalination technologies include reverse osmosis (RO) membranes and thermal desalination, with the most common thermal desalination technology being low-temperature multi-effect distillation (LW-MED).

[0003] like Figure 4 As shown, the existing LW-MED process operates based on the countercurrent flow of evaporating steam and seawater feed. The process feed seawater is first introduced into the cold effect, where it partially evaporates by receiving the latent heat of condensation from the steam in the adjacent, hotter effect. The remaining seawater in each effect, slightly heated and concentrated, is then pumped to the next, hotter effect. A portion of the regenerated steam from the low-temperature effect is compressed and recycled back to the first effect via a thermocompressor, significantly improving the process's thermal efficiency and thus the unit's performance ratio.

[0004] In the LW-MED process, cooling water is required through a cooling tower, including:

[0005] 1. The regeneration steam generated in the final effect is split into two paths. One path enters the falling film condenser, where it condenses and heats the incoming seawater to a controlled fixed temperature while also degassing the seawater. The second path of regeneration steam, which is excess from heating the incoming seawater, enters the forced circulation condenser, where it is cooled by cooling water from the circulating cooling tower.

[0006] 2. Non-condensable gases (NCGs) must be removed from the process because they can affect heat transfer efficiency and cause corrosion. NCGs are piped to the tube side of the heat rejection condenser for concentration. Here, along with NCGs from the shell side (seawater side) of the falling film condenser, they are extracted from the process via a three-stage steam ejector pump with a direct contact condenser. The condensate from the direct contact condenser circulates in a closed loop. The NCG condensate is cooled by cooling water from the cooling tower through a plate heat exchanger.

[0007] 3. In order to ensure that the temperature of the first-effect steam condensate (initial temperature of about 68°C) meets the temperature requirements of process water, the first-effect steam condensate is cooled by cooling water from the cooling tower through a plate heat exchanger.

[0008] The above three processes all use cooling water from the circulating cooling tower. After passing through their respective forced circulation condensers (or plate heat exchangers), the temperature rises, and after being gathered into one path, it returns to the circulating cooling tower, exchanges with the air to release heat, and then circulates in a closed loop.

[0009] However, the LW-MED process has the following technical problems:

[0010] 1. When the LW-MED device is in normal operation, multiple circulating cooling towers are usually needed to take away the heat continuously generated during the operation of the device. When several sets of LW-MED devices share one circulating cooling tower system, the reliability and flexibility of the LW-MED device during operation are greatly reduced.

[0011] 2. The circulating cooling tower system continuously takes away the generated heat and eventually enters the atmosphere through air heat exchange, resulting in the loss of heat and working medium.

[0012] 3. To ensure that the circulating seawater of the circulating cooling tower system does not scale, scale inhibitors, bactericides and other reagents need to be added, and continuous water replenishment and pollution discharge are needed to ensure that the system does not corrode and scale, resulting in high maintenance costs and waste of working medium. SUMMARY

[0013] To solve the above problems, the present application provides a system and method for improving the water production ratio of thermal seawater desalination, which can increase the reliability and flexibility of the system, avoid the loss of heat and working medium, reduce the amount of primary effect heat exchange steam and the operation and maintenance cost of the circulating cooling tower system, and improve the water production ratio.

[0014] To achieve the purpose of the present application, the present application provides the following technical solutions:

[0015] First aspect:

[0016] The present application provides a system for improving the water production ratio of thermal seawater desalination, comprising: a seawater pipeline, a cooling water pipeline, and an energy-saving pipeline.

[0017] The output end of the seawater pipeline is in communication with the input end of the multiple-effect evaporation system to form a passage, and is in communication with the falling film condenser, the concentrated brine inlet water heat exchanger, and the product water heat exchanger, respectively.

[0018] The input end and the output end of the cooling water pipeline are in communication with the cooling tower to form a loop, and are in communication with the NCG condensate heat exchanger, the forced circulation condenser, and the cooling water side of the condensate heat exchanger, respectively.

[0019] The energy-saving pipeline comprises a first pipeline, a second pipeline, a third pipeline, and a fourth pipeline.

[0020] One end of the first pipeline is in communication with the seawater pipeline, and the other end is in communication with the cooling water pipeline at the front end of the NCG condensate heat exchanger.

[0021] One end of the second pipeline is in communication with the first pipeline, and the other end is in communication with the cooling water pipeline at the front end of the condensate heat exchanger.

[0022] One end of the third pipeline is in communication with the cooling water pipeline at the rear end of the NCG condensate heat exchanger, and the other end is in communication with the seawater pipeline at the rear end of the falling film condenser;

[0023] One end of the fourth pipeline is in communication with the cooling water pipeline at the rear end of the condensate heat exchanger, and the other end is in communication with the third pipeline;

[0024] The first pipeline has a first regulating valve between the connection end of the seawater pipeline and the connection end of the second pipeline;

[0025] The first pipeline has a second regulating valve between the connection end of the cooling water pipeline and the connection end of the second pipeline;

[0026] The second pipeline has a third regulating valve;

[0027] The third pipeline has a fourth regulating valve between the connection end of the cooling water pipeline and the connection end of the fourth pipeline;

[0028] The fourth pipeline has a fifth regulating valve;

[0029] The cooling water pipeline has a sixth regulating valve between the connection end of the third pipeline and the connection end of the cooling water pipeline NCG condensate heat exchanger branch and the cooling water pipeline output main branch;

[0030] The cooling water pipeline has a seventh regulating valve between the connection end of the fourth pipeline and the connection end of the cooling water pipeline condensate heat exchanger branch and the cooling water pipeline output main branch.

[0031] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a concentrated brine pipeline;

[0032] The input end and the output end of the concentrated brine pipeline form a loop with the concentrated brine flash unit and are in communication with the concentrated brine side of the concentrated brine condensate heat exchanger;

[0033] The concentrated brine pipeline further has a second output end in communication with the concentrated brine discharge unit and in communication with the concentrated brine feed water heat exchanger;

[0034] The concentrated brine output end of the falling film condenser is in communication with the concentrated brine pipeline.

[0035] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a product water pipeline;

[0036] The output end of the product water pipeline is in communication with a product water system to form a passage, and is in communication with a product water side of the product water heat exchanger;

[0037] The product water output end of the falling film condenser and the forced circulation condenser is in communication with the product water pipeline.

[0038] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a condensate water pipeline;

[0039] The output end of the condensate water pipeline is in communication with a boiler feed water system to form a passage, and is in communication with a condensate water side of the concentrated brine condensate water heat exchanger and the condensate water heat exchanger;

[0040] The condensate water pipeline further comprises a condensate water circulation branch; the output end and the input end of the condensate water circulation branch are in communication with an NCG condenser to form a loop, and are in communication with, in sequence, a condensate water side of an NCG condensate water heat exchanger and a condensate water system.

[0041] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a steam pipeline;

[0042] The input end of the steam pipeline is in communication with the output end of the multi-effect evaporation system, the output end is in communication with the NCG condenser and the atmosphere through the NCG ejector to form a passage, and is in communication with a steam side of the falling film condenser and the forced circulation condenser, respectively.

[0043] In a possible implementation, a first emptying valve is arranged on the first pipeline between the connection end of the first pipeline and the first regulating valve.

[0044] In a possible implementation, a second emptying valve is further arranged on the third pipeline between the connection end of the third pipeline and the fourth regulating valve.

[0045] In a possible implementation, the input end of the NCG ejector is further in communication with a unit auxiliary steam system.

[0046] The second aspect is a system for increasing the water production ratio of thermal seawater desalination, comprising:

[0047] The second aspect is a system for increasing the water production ratio of thermal seawater desalination, comprising:

[0048] When the temperature of the raw seawater is greater than 15 degrees Celsius, the first regulating valve, the second regulating valve, the third regulating valve, the fourth regulating valve and the fifth regulating valve are closed, and the sixth regulating valve and the seventh regulating valve are opened.

[0049] When the original seawater temperature is less than or equal to 15 degrees Celsius, the sixth regulating valve and the seventh regulating valve are closed, and the first regulating valve, the second regulating valve, the third regulating valve, the fourth regulating valve and the fifth regulating valve are opened.

[0050] In a possible implementation, the opening degree of the second regulating valve is less than 60%, and the opening degree of the third regulating valve is less than 58%.

[0051] Beneficial effects:

[0052] The system and method for improving the water production ratio of thermal seawater desalination provided in the application can solve the problem of energy waste caused by the cooling tower running in the seawater desalination system when the original seawater temperature is lower than 15 degrees Celsius; by flexibly adjusting the opening degree of the second regulating valve, the seawater flow on the cooling water side of the NCG condensate water heat exchanger is precisely controlled under the premise of meeting the cooling of the NCG condensate water heat exchanger, so that the pressure head loss of the clean water pump is avoided; by flexibly adjusting the opening degree of the third regulating valve, the seawater flow on the cooling water side of the condensate water heat exchanger is precisely controlled under the premise of meeting the condensate water discharge temperature, so that the pressure head loss of the clean water pump is further avoided; and the seawater used for cooling is introduced into the multi-effect evaporator, so that the working medium and heat are recovered, and the water production ratio of seawater desalination is improved; the drain valve is added to the backwater pipeline to solve the problem of system drainage and anti-freezing during the maintenance of the seawater desalination system or during the winter shutdown. BRIEF DESCRIPTION OF DRAWINGS

[0053] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application together with the embodiments thereof, and explain the application, but do not form a limitation on the application;

[0054] Figure 1 A structural schematic diagram of a system for improving the water production ratio of thermal seawater desalination is provided for the embodiments of the application;

[0055] Figure 2 A structural schematic diagram of an energy-saving pipeline of a system for improving the water production ratio of thermal seawater desalination is provided for the embodiments of the application

[0056] Figure 3 A flowchart of a method for improving the water production ratio of thermal seawater desalination is provided for the embodiments of the application;

[0057] Figure 4 A structural schematic diagram of a system for improving the water production ratio of thermal seawater desalination is provided for the embodiments of the application;

[0058] Figure 5 A color structural schematic diagram of a system for improving the water production ratio of thermal seawater desalination is provided for the embodiments of the application.

[0059] Reference signs: 1-first regulating valve; 2-second regulating valve; 3-third regulating valve; 4-fourth regulating valve; 5-fifth regulating valve; 6-sixth regulating valve; 7-seventh regulating valve; 8-first exhaust valve; 9-second exhaust valve; 10-falling film condenser; 11-forced circulation condenser; 12-concentrated brine feed water heat exchanger; 13-product water heat exchanger; 14-condensed water heat exchanger; 15-concentrated brine condensed water heat exchanger; 16-NCG condensed water heat exchanger; 17-NCG ejector; 18-NCG condenser; 19-cooling tower; 20-first pipeline; 21-second pipeline; 22-third pipeline; 23-fourth pipeline. DETAILED DESCRIPTION

[0060] For the purpose, technical solutions and advantages of the present application to be clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0061] The terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features; in the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0062] Embodiment 1

[0063] Figures 1-2 A system for improving the water production ratio of thermal seawater desalination provided by the embodiments of the present application, comprising: a seawater pipeline, a cooling water pipeline, an energy-saving pipeline;

[0064] The output end of the seawater pipeline is in communication with the input end of the multi-effect evaporation system to form a passage, and is in communication with the falling film condenser 10, the concentrated brine feed water heat exchanger 12 and the product water heat exchanger 13, respectively;

[0065] The input end and the output end of the cooling water pipeline are in communication with the cooling tower to form a loop, and are in communication with the NCG condensed water heat exchanger 16, the forced circulation condenser 11 and the cooling water side of the condensed water heat exchanger 14, respectively;

[0066] The energy-saving pipeline comprises: a first pipeline 20, a second pipeline 21, a third pipeline 22 and a fourth pipeline 23;

[0067] One end of the first pipeline 20 is communicated with the seawater pipeline, and the other end is communicated with the cooling water pipeline in front end of the NCG condensate water heat exchanger 16;

[0068] One end of the second pipeline 21 is communicated with the first pipeline 20, and the other end is communicated with the cooling water pipeline in front end of the condensate water heat exchanger 14;

[0069] One end of the third pipeline 22 is communicated with the cooling water pipeline in rear end of the NCG condensate water heat exchanger 16, and the other end is communicated with the seawater pipeline in rear end of the falling film condenser 10;

[0070] One end of the fourth pipeline 23 is communicated with the cooling water pipeline in rear end of the condensate water heat exchanger 14, and the other end is communicated with the third pipeline 22;

[0071] The first regulating valve 1 is arranged between the connection end of the first pipeline 20 and the connection end of the second pipeline 21;

[0072] The second regulating valve 2 is arranged between the connection end of the first pipeline 20 and the connection end of the cooling water pipeline;

[0073] The third regulating valve 3 is arranged on the second pipeline 21;

[0074] The fourth regulating valve 4 is arranged between the connection end of the third pipeline 22 and the connection end of the fourth pipeline 23;

[0075] The fifth regulating valve 5 is arranged on the fourth pipeline 23;

[0076] The sixth regulating valve 6 is arranged between the connection end of the third pipeline 22 and the connection end of the cooling water pipeline NCG condensate water heat exchanger branch and the cooling water pipeline output main branch;

[0077] The seventh regulating valve 7 is arranged between the connection end of the fourth pipeline 23 and the connection end of the cooling water pipeline condensate water heat exchanger branch and the cooling water pipeline output main branch.

[0078] Optionally, the cooling water pipeline transports cooling water through a cooling water circulating pump to provide a cooling source for the NCG condensate water heat exchanger 16, the forced circulation condenser 11 and the condensate water heat exchanger 14.

[0079] Optionally, the input end of the seawater pipeline is communicated with the output end of a seawater pretreatment system, which is used for transporting seawater into the concentrated brine feed water heat exchanger 12, the product water heat exchanger 13 and the falling film condenser 10 to exchange heat, and then into the multi-effect evaporator, so as to improve the heat circulation efficiency of the system.

[0080] Optionally, the energy saving pipeline is as shown in the dashed line. Figure 2

[0081] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a concentrated brine pipeline.

[0082] The input end and the output end of the concentrated brine pipeline form a loop with the concentrated brine flash unit and are in communication with the concentrated brine side of the concentrated brine condensate heat exchanger 15.

[0083] The concentrated brine pipeline further has a second output end in communication with the concentrated brine discharge unit and in communication with the concentrated brine feed water heat exchanger 12.

[0084] The concentrated brine output end of the falling film condenser 10 is in communication with the concentrated brine pipeline.

[0085] The concentrated brine pipeline receives the discharged concentrated brine of the falling film condenser 10 and exchanges heat with the concentrated brine feed water heat exchanger 12 and the concentrated brine condensate heat exchanger 15 respectively, thereby improving the heat circulation efficiency of the system.

[0086] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a product water pipeline.

[0087] The output end of the product water pipeline is in communication with the product water system to form a passage and is in communication with the product water side of the product water heat exchanger.

[0088] The product water output end of the falling film condenser 10 and the forced circulation condenser 11 is in communication with the product water pipeline.

[0089] The product water pipeline receives the product water output by the falling film condenser 10 and the forced circulation condenser 11, and the product water exchanges heat in the product water heat exchanger 13, thereby improving the heat circulation efficiency of the system.

[0090] In a possible implementation, the system for increasing the water production ratio of thermal seawater desalination further comprises a condensate water pipeline.

[0091] The output end of the condensate water pipeline is in communication with the boiler feed water system to form a passage and is in communication with the concentrated brine condensate heat exchanger 15 and the condensate water side of the condensate water heat exchanger 14.

[0092] The condensate water pipeline further comprises a condensate water circulation branch, and the output end and the input end of the condensate water circulation branch form a loop with the NCG condenser 18 and are in communication with the condensate water side of the NCG condensate heat exchanger 16 and the condensate water system in sequence.

[0093] ​The condensate water pipeline exchanges heat with the concentrated brine condensate water heat exchanger 15 and the condensate water heat exchanger 14, improves the heat circulation efficiency of the system, and the condensate water circulation branch is used to collect the condensate water output by the NCG condenser 18, and then exchanges heat with the NCG condensate water heat exchanger 16. The partially cooled condensate water is returned to the NCG condenser 18, and the excess condensate water flows into the condensate water system.

[0094] In a possible implementation, the system for improving the water production ratio of thermal seawater desalination further comprises a steam pipeline;

[0095] The input end of the steam pipeline is in communication with the output end of the multi-effect evaporation system, the output end is in communication with the atmosphere through the NCG ejector 17 and the NCG condenser 18 to form a passage, and is in communication with the steam side of the falling film condenser 10 and the forced circulation condenser 11 respectively.

[0096] The input end of the steam pipeline is in communication with the multi-effect evaporator, used to receive the steam output by the multi-effect evaporator, and the steam is condensed in the forced circulation condenser 11 and the falling film condenser 10. The non-condensable gas (NCG) is further condensed in the NCG condenser 18 for further condensate water collection and gas cooling, and finally discharged into the atmosphere.

[0097] In a possible implementation, the first emptying valve 8 is arranged on the first pipeline between the connection end of the first pipeline and the first regulating valve 1, and is used to empty the water in the system during maintenance.

[0098] In a possible implementation, the second emptying valve 9 is arranged on the third pipeline between the connection end of the third pipeline and the fourth regulating valve, and is used to empty the water in the system during maintenance.

[0099] In a possible implementation, the input end of the NCG ejector is further in communication with the unit auxiliary steam system, and is used to adjust the pressure and recover steam.

[0100] In a possible implementation, in order to facilitate the understanding of the seawater pipeline, the cooling water pipeline, the energy-saving pipeline, the concentrated brine pipeline, the product water pipeline, the condensate water pipeline and the steam pipeline in the present application, a color structural schematic diagram is provided as shown in Figure 5 The seawater pipeline is shown as dark green, the cooling water pipeline is shown as light yellow, the energy-saving pipeline is shown as a black dashed line, the concentrated brine pipeline is shown as dark blue, the product water pipeline is shown as sky blue, the condensate water pipeline is shown as light green, and the steam pipeline is shown as red.

[0101] Example 2

[0102] Figure 3A method for improving the water production ratio of thermal seawater desalination provided by the embodiments of the present application, comprising:

[0103] When the raw seawater temperature is greater than 15 degrees Celsius, the first regulating valve 1, the second regulating valve 2, the third regulating valve 3, the fourth regulating valve 4, and the fifth regulating valve 5 are closed, and the sixth regulating valve 6 and the seventh regulating valve 7 are opened.

[0104] When the raw seawater temperature is less than or equal to 15 degrees Celsius, the sixth regulating valve 6 and the seventh regulating valve 7 are closed, and the first regulating valve 1, the second regulating valve 2, the third regulating valve 3, the fourth regulating valve 4, and the fifth regulating valve 5 are opened.

[0105] Wherein, the raw seawater temperature is the temperature of seawater before entering the seawater desalination system, when the raw seawater temperature is greater than 15 degrees Celsius, the cooling tower works normally to provide cooling water for the NCG condensate water heat exchanger 16, the forced circulation condenser 11, and the condensate water heat exchanger 14; when the raw seawater temperature is less than or equal to 15 degrees Celsius, seawater is used to provide cooling for the NCG condensate water heat exchanger 16, the forced circulation condenser 11, and the condensate water heat exchanger 14, and the cooling tower is closed to further achieve water and electricity saving.

[0106] In a possible implementation, the opening degree of the second regulating valve 2 is less than 60%, and the opening degree of the third regulating valve 3 is less than 58%.

[0107] Wherein, by controlling the opening degree of the second regulating valve 2, the amount of cooling water entering the NCG condensate water heat exchanger 16 can be accurately controlled, so as to control the temperature of the cooling water side and the condensate water side of the NCG condensate water heat exchanger 16; by controlling the opening degree of the third regulating valve 3, the amount of cooling water entering the condensate water heat exchanger 14 can be accurately controlled, so as to control the temperature of the cooling water / condensate water side of the condensate water heat exchanger 14, and the specific parameters are as follows:

[0108] NCG condensate water heat exchanger 16 operating parameters:

[0109]

[0110] Condensate water heat exchanger 14 operating parameters:

[0111]

[0112] In a possible implementation, when the seawater desalination system is shut down in winter or needs to be overhauled, the first emptying valve 8 and the second emptying valve 9 are opened to empty the stored water in the system, so as to achieve winter anti-freezing or facilitate overhauling.

[0113] Technical effects and principles:

[0114] Adopting the control method of the embodiment of the present application, when the seawater temperature is less than or equal to 15 degrees Celsius, the heat energy of the NCG condensate water heat exchanger 16 and the condensate water heat exchanger 14 is recovered to the feed water system through the cooling of the original seawater, avoiding the loss of the working medium and the loss of heat, and the recovered heat is used to heat the feed water. Since the temperature of the feed water of the first effect in the operation of the seawater desalination system is 70°, the amount of steam used for heating the first effect is correspondingly reduced. Guided by the "black box" theory, the boundary of the heat balance of the entire seawater desalination system is researched (taking a single set of seawater desalination system with a design value of 25000 tons / day in a coastal area as a calculation model):

[0115] 1) Calculate the boundary conditions:

[0116] The power steam parameters of the first effect are: pressure 0.5 MPa, temperature 70° (saturated steam with superheat degree of 0°);

[0117] Circulating cooling water: winter inlet water temperature 6°, return water temperature (see table below), flow rate (100+140) t / h;

[0118] The specific heat capacity of the cooling seawater is 3.9795*103 J / (kg.°C) for convenience of calculation (salinity 4.9%, temperature 42℃);

[0119] Latent heat of vaporization: for convenience of calculation, the latent heat is 2675.9 kJ / kg (100℃).

[0120]

[0121] Change of water production ratio:

[0122] The original design of a single set of seawater desalination has a water production of 25000 t / d, and the first effect steam consumption is 69 t / h, and the water production ratio is 15.096 (see the following formula):

[0123] Water production ratio = water production / first effect steam consumption

[0124] = 25000 t / d*24*69 t / h

[0125] = 15.096

[0126] According to the operation mode of the present application, the water production ratio is 15.945, which is calculated as follows:

[0127] Water production ratio = water production / first effect steam consumption

[0128] = 25000 t / d*24*(69-3.675) t / h

[0129] = 15.945

[0130] Through the heat balance as the boundary to calculate, the seawater desalination water production ratio is increased by 0.849 before the technology is improved, and the macroeconomic benefit is obvious.

[0131] In several embodiments provided in the present application, it should be understood that the disclosed system, module and method can be implemented in other ways. For example, the above-described module embodiments are only illustrative, for example, the division of units is only a logical function division, and actual implementation can have another division mode, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed can be through some interface, indirect coupling or communication connection between modules or units, which can be electrical, mechanical or other forms.

[0132] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them. The present application is not limited to the exact structure described above and shown in the drawings, and the specific implementation of the present application should not be limited to the description. For ordinary skilled in the art to which the present application belongs, various changes and modifications made without departing from the concept of the present application should be considered to belong to the protection scope of the present application.

Claims

1. A system for increasing the water production ratio of thermal desalination of sea water, characterized in that, Comprising: sea water pipeline, energy saving pipeline, cooling water pipeline, condensate water pipeline, steam pipeline; the output end of the sea water pipeline is communicated with the input end of the multi-effect evaporation system to form a passage, and is respectively communicated with a falling film condenser (10), a concentrated brine feeding water heat exchanger (12), and a product water heat exchanger (13); the input end and the output end of the cooling water pipeline are communicated with a cooling tower to form a loop, and are respectively communicated with an NCG condensate water heat exchanger (16), a forced circulation condenser (11), and the cooling water side of a condensate water heat exchanger (14); the output end of the condensate water pipeline is communicated with a boiler feed water system to form a passage, and is communicated with a concentrated brine condensate water heat exchanger (15) and the condensate water side of the condensate water heat exchanger (14); the condensate water pipeline further comprises a condensate water circulation branch; the output end and the input end of the condensate water circulation branch are communicated with an NCG condenser (18) to form a loop, and are communicated with the condensate water side of the NCG condensate water heat exchanger (16) and a condensate water system in sequence; the input end of the steam pipeline is communicated with the output end of the multi-effect evaporation system, the output end is communicated with the NCG condenser (18) through an NCG ejector (17) to form a passage with the atmosphere, and is respectively communicated with the steam side of the falling film condenser (10) and the forced circulation condenser (11); the energy saving pipeline comprises a first pipeline (20), a second pipeline (21), a third pipeline (22), and a fourth pipeline (23); one end of the first pipeline (20) is communicated with the sea water pipeline, and the other end is communicated with the cooling water pipeline at the front end of the NCG condensate water heat exchanger (16); one end of the second pipeline (21) is communicated with the first pipeline (20), and the other end is communicated with the cooling water pipeline at the front end of the condensate water heat exchanger (14); one end of the third pipeline (22) is communicated with the cooling water pipeline at the rear end of the NCG condensate water heat exchanger (16), and the other end is communicated with the sea water pipeline at the rear end of the falling film condenser (10); one end of the fourth pipeline (23) is communicated with the cooling water pipeline at the rear end of the condensate water heat exchanger (14), and the other end is communicated with the third pipeline (22). The first pipe (20) has a first adjusting valve (1) between the connecting end of the seawater pipe and the connecting end of the second pipe (21); the first pipe (20) has a second adjusting valve (2) between the connecting end of the cooling water pipe and the connecting end of the second pipe (21); the second pipe (21) has a third adjusting valve (3); the third pipe (22) has a fourth adjusting valve (4) between the connecting end of the cooling water pipe and the connecting end of the fourth pipe (23), and the seawater for cooling is introduced into a multi-effect evaporation system, so that the working medium and heat are recovered, and the seawater desalination water production ratio is improved; the fourth pipe (23) has a fifth adjusting valve (5); when the temperature of the raw seawater is reduced to 15 degrees Celsius or below, the first adjusting valve (1), the second adjusting valve (2), the third adjusting valve (3), the fourth adjusting valve (4) and the fifth adjusting valve (5) are simultaneously opened; The cooling water pipe has a sixth adjusting valve (6) between the connecting end of the third pipe (22) and the connecting end of the cooling water pipe NCG condensate water heat exchanger branch and the cooling water pipe output main branch; the cooling water pipe has a seventh adjusting valve (7) between the connecting end of the fourth pipe (23) and the connecting end of the cooling water pipe condensate water heat exchanger branch and the cooling water pipe output main branch; in the case that the temperature of the raw seawater is reduced to 15 degrees Celsius or below, the sixth adjusting valve (6) and the seventh adjusting valve (7) are simultaneously switched from the self-opening state to the closed state.

2. The system for improving the gain output ratio of thermal desalination according to claim 1, characterized in that, Further comprising: A concentrated brine pipe; The input end and the output end of the concentrated brine pipe form a loop with the concentrated brine flash evaporation unit, and are in communication with the concentrated brine side of the concentrated brine condensate water heat exchanger (15); The concentrated brine pipe further has a second output end, which is in communication with the concentrated brine discharge unit and the concentrated brine feed water heat exchanger (12); The concentrated brine output end of the falling film condenser (10) is in communication with the concentrated brine pipe.

3. The system for improving the gain output ratio of thermal desalination according to claim 1, characterized in that, Further comprising: A product water pipe; The output end of the product water pipe is in communication with the product water system to form a passage, and is in communication with the product water side of the product water heat exchanger; The product water output end of the falling film condenser (10) and the forced circulation condenser (11) are in communication with the product water pipe.

4. The system for improving the gain output ratio of thermal desalination according to claim 1, characterized in that, The first pipe has a first emptying valve (8) between the connecting end of the first pipe and the first adjusting valve (1).

5. The system for improving the gain output ratio of thermal desalination according to claim 1, characterized in that, The third pipe further has a second emptying valve (9) between the connecting end of the third pipe and the fourth adjusting valve.

6. The system for improving the gain output ratio of thermal desalination according to claim 1, characterized in that, The input end of the NCG ejector (17) is further in communication with the unit auxiliary steam system.

7. A method of increasing the water production ratio of a thermal desalination process, the method employing the system of any one of claims 1 to 6, characterised in that, Including: When the temperature of the raw seawater is greater than 15 degrees Celsius, the first adjusting valve (1), the second adjusting valve (2), the third adjusting valve (3), the fourth adjusting valve (4) and the fifth adjusting valve (5) are closed, and the sixth adjusting valve (6) and the seventh adjusting valve (7) are opened; When the original seawater temperature is less than or equal to 15 degrees Celsius, the sixth regulating valve (6) and the seventh regulating valve (7) are closed, and the first regulating valve (1), the second regulating valve (2), the third regulating valve (3), the fourth regulating valve (4) and the fifth regulating valve (5) are opened.

8. The method of improving the gain output ratio of thermal desalination according to claim 7, characterized in that, The opening of the second regulating valve (2) is less than 60%, and the opening of the third regulating valve (3) is less than 58%.

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