Hot film coupling seawater desalination system and seawater coupling method

Abstract

The invention belongs to the field of seawater desalination, and provides a hot film coupling seawater desalination system and a seawater coupling method. According to the hot film coupling seawater desalination system, the input end of a flash tank is connected with power plant incoming water, and the output end of the flash tank is connected with the first input end of a multi-effect distillation evaporator; a path of seawater is introduced into the second input end of the multi-effect distillation evaporator, heated seawater is generated at the output end of the multi-effect distillation evaporator and conveyed to the multi-effect distillation condenser, and produced water condensed by the multi-effect distillation condenser enters a pure water tank; the filtering device is used for filtering the other path of seawater and conveying the filtered seawater to the seawater reverse osmosis system; part of seawater reverse osmosis produced water of the seawater reverse osmosis system is conveyed to the fresh water reverse osmosis system; output paths of the other part of seawater reverse osmosis produced water of the seawater reverse osmosis system and fresh water reverse osmosis produced water of the fresh water reverse osmosis system are determined according to the current seawater temperature.

Description

Technical Field

[0001] The invention belongs to the field of seawater desalination, and in particular relates to a thermal film coupled seawater desalination system and a seawater coupling method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Seawater desalination methods are divided into two categories: membrane method and thermal method. Among them, membrane method mainly refers to reverse osmosis method; thermal method includes multi-stage flash evaporation and low-temperature multi-effect method. For colder areas, thermal desalination systems have the disadvantages of high energy consumption, high steam demand, long start-up and shutdown time, large footprint, large impact of concentrated seawater discharge on the environment, and the need to set up a separate cooling water source. The disadvantage of membrane desalination is that the heat source is used to heat the raw seawater for about 3 months in winter, but the membrane heating system will be idle for the remaining 9 months. Low system utilization and idle state will also make related systems more prone to failure, increasing the difficulty of maintenance. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a thermal membrane coupled seawater desalination system and a seawater coupling method, which combine the advantages of membrane and thermal seawater desalination, fully utilize thermal energy, improve the utilization rate of the system, and reduce equipment investment while meeting users' requirements for water quality.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A first aspect of the present invention provides a thermal membrane coupled seawater desalination system.

[0007] A thermal membrane coupled seawater desalination system, comprising: a flash tank, a filtering device, a multi-effect distillation evaporator, a multi-effect distillation condenser, a pure water tank, a fresh water reverse osmosis system and a seawater reverse osmosis system;

[0008] The input end of the flash tank is connected to hot water from the power plant, and the output end is connected to the first input end of the multiple-effect distillation evaporator; the second input end of the multiple-effect distillation evaporator is connected to seawater, and the output end of the multiple-effect distillation evaporator produces heated seawater and transports it to the multiple-effect distillation condenser, and the produced water condensed by the multiple-effect distillation condenser enters the pure water tank;

[0009] The filtering device is used to filter another path of seawater and transport the filtered seawater to the seawater reverse osmosis system; part of the seawater reverse osmosis water produced by the seawater reverse osmosis system is transported to the freshwater reverse osmosis system; the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system both determine their output paths according to the current seawater temperature.

[0010] As an implementation mode, if the current seawater temperature is lower than a preset temperature threshold, another part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are directly transported to the pure water tank according to the current seawater temperature.

[0011] As an implementation method, if the current seawater temperature is lower than a preset temperature threshold, the pure water tank contains mixed water of three water qualities: water produced by condensation of a multi-effect distillation condenser, water produced by seawater reverse osmosis, and water produced by freshwater reverse osmosis.

[0012] As an implementation mode, the salt content of the mixed water is determined by the output of the multiple-effect distillation condenser, the seawater reverse osmosis system and the fresh water reverse osmosis system.

[0013] As an implementation mode, if the current seawater temperature is not lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both transported to the multi-effect distillation condenser according to the current seawater temperature, and the produced water condensed by the multi-effect distillation condenser enters the pure water tank.

[0014] As an embodiment, the thermal film coupled seawater desalination system further includes: a first clear water tank, wherein the first clear water tank is connected to the second input end of the multiple-effect distillation evaporator.

[0015] As an implementation manner, the thermal membrane coupled seawater desalination system further includes: a second clear water tank, wherein the second clear water tank is connected to the input end of the filtering device.

[0016] As an implementation mode, if the current seawater temperature is lower than a preset temperature threshold, the water heated by heat exchange in the multi-effect distillation condenser is returned to the second clear water tank.

[0017] A second aspect of the present invention provides a seawater coupling method based on the thermal membrane coupled seawater desalination system as described above.

[0018] A seawater coupling method based on the thermal film coupled seawater desalination system as described above comprises:

[0019] The seawater is divided into two routes, one of which is transported to the multi-effect distillation evaporator, and the other is filtered by the filter device and then transported to the seawater reverse osmosis system; part of the seawater reverse osmosis water produced by the seawater reverse osmosis system is transported to the fresh water reverse osmosis system;

[0020] The hot water from the power plant is transported to the multiple-effect distillation evaporator after passing through the flash tank, and the seawater is transported to the multiple-effect distillation condenser after absorbing heat in the multiple-effect distillation evaporator;

[0021] According to the current seawater temperature, it is determined whether the other part of the seawater reverse osmosis water of the seawater reverse osmosis system and the freshwater reverse osmosis water of the freshwater reverse osmosis system are output to the pure water tank or the multi-effect distillation condenser.

[0022] As an implementation mode, if the current seawater temperature is lower than a preset temperature threshold, another portion of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both directly transported to the pure water tank according to the current seawater temperature;

[0023] If the current seawater temperature is not lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both transported to the multi-effect distillation condenser according to the current seawater temperature, and the produced water condensed by the multi-effect distillation condenser enters the pure water tank.

[0024] The beneficial effects of the present invention are:

[0025] (1) The thermal membrane coupled seawater desalination system of the present invention integrates a flash evaporation system, a multi-effect distillation system, a freshwater reverse osmosis system and a seawater reverse osmosis system. The seawater coupling mode in the thermal membrane coupled seawater desalination system is adjusted according to the current seawater temperature, thereby solving the problem of high requirements for drainage temperature rise in some areas and meeting the user's requirements for the salt content of fresh water.

[0026] (2) The concentrated water that meets the discharge temperature requirements of the sea obtained by the thermal membrane coupled seawater desalination system of the present invention can be more than 2°C lower than that of the conventional thermal membrane coupling method; and by adjusting the output of the multi-effect distillation system, the fresh water reverse osmosis system and the seawater reverse osmosis system, fresh water that meets the user's salt content requirements can be obtained, while reducing the investment in the overall equipment as much as possible.

[0027] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a thermal film coupled seawater desalination system under winter conditions according to an embodiment of the present invention;

[0030] Figure 2 This is a thermal film coupled seawater desalination system under summer conditions according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] Terminology explanation:

[0035] Thermal desalination: refers to the technology of using high temperature to separate water vapor and salt in seawater. The commonly used methods are multi-stage flash evaporation and low-temperature multi-effect.

[0036] Membrane desalination: also known as reverse osmosis desalination, is currently the mainstream desalination technology. Its principle is that under the drive of osmotic pressure, the solvent (water) enters the low-pressure side of the membrane through the semi-permeable membrane, while other components (salts) in the solution are blocked on the high-pressure side of the membrane and discharged with the concentrated water, thereby achieving an effective separation process. Reverse osmosis desalination technology mainly uses the selective permeability of the reverse osmosis membrane to achieve the enrichment of fresh water in seawater.

[0037] Thermal membrane coupled desalination: refers to a desalination process that combines thermal desalination and membrane desalination.

[0038] Seawater coupling: refers to the secondary utilization of seawater in thermal desalination and membrane desalination process systems in order to fully utilize the thermal energy of seawater.

[0039] In one or more embodiments, a thermal membrane coupled seawater desalination system is provided, comprising: a flash tank, a filtration device, a multiple-effect distillation evaporator, a multiple-effect distillation condenser, a pure water tank, a fresh water reverse osmosis system, and a seawater reverse osmosis system;

[0040] The input end of the flash tank is connected to hot water from the power plant, and the output end is connected to the first input end of the multiple-effect distillation evaporator; the second input end of the multiple-effect distillation evaporator is connected to seawater, and the output end of the multiple-effect distillation evaporator produces heated seawater and transports it to the multiple-effect distillation condenser, and the produced water condensed by the multiple-effect distillation condenser enters the pure water tank;

[0041] The filtering device is used to filter another path of seawater and transport the filtered seawater to the seawater reverse osmosis system; part of the seawater reverse osmosis water produced by the seawater reverse osmosis system is transported to the freshwater reverse osmosis system; the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system both determine their output paths according to the current seawater temperature.

[0042] In some optional embodiments, such as Figure 1 As shown, if the current seawater temperature is lower than a preset temperature threshold (e.g., 15°C), another portion of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both directly transported to the pure water tank according to the current seawater temperature.

[0043] It should be noted here that the preset temperature threshold can be specifically set according to actual conditions. The working condition where the current seawater temperature is lower than the preset temperature threshold (eg, 15° C.) belongs to the winter working condition.

[0044] If the current seawater temperature is lower than the preset temperature threshold, the pure water tank contains a mixture of water produced by the multi-effect distillation condenser, seawater reverse osmosis and freshwater reverse osmosis. The concentrated seawater produced by seawater reverse osmosis can be reused or directly discharged.

[0045] The salt content of the mixed water is determined by the output of the multi-effect distillation condenser, the seawater reverse osmosis system and the freshwater reverse osmosis system. Since the salt content of the three produced waters is different, the ratio of the three produced waters can be adjusted according to the detailed requirements of the end user on the salt content, that is, the output of the multi-effect distillation condenser, the seawater reverse osmosis system and the freshwater reverse osmosis system can be adjusted.

[0046] like Figure 2 As shown, if the current seawater temperature is not lower than the preset temperature threshold (for example, 15°C), the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both transported to the multiple-effect distillation condenser according to the current seawater temperature, and the produced water condensed by the multiple-effect distillation condenser enters the pure water tank.

[0047] In this embodiment, the thermal film coupled seawater desalination system further includes: a first clear water tank, wherein the first clear water tank is connected to the second input end of the multiple-effect distillation evaporator.

[0048] The thermal film coupled seawater desalination system further includes: a second clear water tank connected to the input end of the filter device. If the current seawater temperature is lower than a preset temperature threshold, the water heated by heat exchange in the multi-effect distillation condenser is returned to the second clear water tank.

[0049] Among them, the water in the first clean water tank and the second clean water tank is transported by flotation after being collected from the water intake pump room.

[0050] In this embodiment, the output end of the seawater reverse osmosis system is connected to the input end of the fresh water reverse osmosis system through a primary fresh water tank.

[0051] In this embodiment, the filtering device includes a V-shaped filter tank and an ultrafiltration device connected in series.

[0052] The seawater coupling method based on the thermal film coupled seawater desalination system as described above comprises:

[0053] Step 1: The seawater is divided into two paths, one of which is transported to a multi-effect distillation evaporator, and the other is filtered by a filter device and then transported to a seawater reverse osmosis system; part of the seawater reverse osmosis water produced by the seawater reverse osmosis system is transported to a fresh water reverse osmosis system;

[0054] Step 2: The hot water from the power plant is transported to the multiple-effect distillation evaporator after passing through the flash tank, and the seawater is transported to the multiple-effect distillation condenser after absorbing heat in the multiple-effect distillation evaporator;

[0055] Step 3: Determine whether the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are output to the pure water tank or the multi-effect distillation condenser according to the current seawater temperature.

[0056] like Figure 1 As shown, if the current seawater temperature is lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are directly transported to the pure water tank according to the current seawater temperature;

[0057] When the current seawater temperature is lower than the preset temperature threshold, i.e., in winter conditions, specifically:

[0058] 1) Part of the low-temperature raw seawater after pretreatment is used as process water and cooling water and enters the multiple-effect distillation condenser respectively;

[0059] 2) After the heat exchange is completed, the temperature of the fresh water and concentrated water produced by the multi-effect distillation condenser rises to the set temperature range;

[0060] 3) The concentrated water after heat exchange is mixed with part of the low-temperature raw seawater after pretreatment and enters the clear water tank. The water in the clear water tank is filtered and then enters the seawater reverse osmosis system;

[0061] 4) The water produced by the seawater reverse osmosis system directly enters the pure water tank, and part of it enters the freshwater reverse osmosis system for further purification. The concentrated water is directly discharged when the temperature meets the discharge standards;

[0062] 5) The fresh water produced by the multi-effect distillation condenser directly enters the pure water tank and is mixed with the water produced by the fresh water reverse osmosis system and the seawater reverse osmosis system. After reaching the required water quality, it is transported to the water use point.

[0063] like Figure 2 As shown, if the current seawater temperature is not lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both transported to the multi-effect distillation condenser according to the current seawater temperature, and then the produced water condensed by the multi-effect distillation condenser enters the pure water tank.

[0064] When the current seawater temperature is not lower than the preset temperature threshold, that is, it is in summer working condition, specifically:

[0065] 1) After pretreatment, part of the low-temperature raw seawater enters the clean water tank, and the water in the clean water tank enters the seawater reverse osmosis system after filtration;

[0066] 2) Part of the low-temperature raw seawater after pretreatment enters the multiple-effect distillation condenser as process water;

[0067] 3) Part of the water produced by the seawater reverse osmosis system enters the freshwater reverse osmosis system for further purification, and the remaining water produced by the seawater reverse osmosis system and the freshwater reverse osmosis system enter the multiple-effect distillation condenser as cooling water for the multiple-effect distillation condenser. After heat exchange, it enters the pure water tank and is mixed with the water produced by the multiple-effect distillation condenser and part of the water produced by the freshwater reverse osmosis system. After reaching the required water quality, it is transported to the water use point;

[0068] 4) The concentrated water after evaporation in the multi-effect distillation condenser is mixed with the concentrated water from the seawater reverse osmosis system and discharged after the temperature meets the discharge standards.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thermal film coupled seawater desalination system, characterized in that: include: Flash tanks, filtration devices, multiple-effect distillation evaporators, multiple-effect distillation condensers, pure water tanks, fresh water reverse osmosis systems and seawater reverse osmosis systems; The input end of the flash tank is connected to hot water from the power plant, and the output end is connected to the first input end of the multiple-effect distillation evaporator; the second input end of the multiple-effect distillation evaporator is connected to seawater, and the output end of the multiple-effect distillation evaporator produces heated seawater and transports it to the multiple-effect distillation condenser, and the produced water condensed by the multiple-effect distillation condenser enters the pure water tank; The filtering device is used to filter another path of seawater and transport the filtered seawater to the seawater reverse osmosis system; part of the seawater reverse osmosis water produced by the seawater reverse osmosis system is transported to the freshwater reverse osmosis system; the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system both determine their output paths according to the current seawater temperature.

2. The thermal film coupled seawater desalination system according to claim 1, characterized in that: If the current seawater temperature is lower than the preset temperature threshold, another part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are directly transported to the pure water tank according to the current seawater temperature.

3. The thermal film coupled seawater desalination system according to claim 1, characterized in that: If the current seawater temperature is lower than the preset temperature threshold, the pure water tank contains mixed water of three water qualities: water produced by condensation of the multi-effect distillation condenser, water produced by seawater reverse osmosis, and water produced by freshwater reverse osmosis.

4. The thermal film coupled seawater desalination system according to claim 3, characterized in that: The salt content of the mixed water is determined by the output of the multi-effect distillation condenser, the seawater reverse osmosis system and the freshwater reverse osmosis system.

5. The thermal film coupled seawater desalination system according to claim 1, characterized in that: If the current seawater temperature is not lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both transported to the multi-effect distillation condenser according to the current seawater temperature, and the produced water condensed by the multi-effect distillation condenser enters the pure water tank.

6. The thermal film coupled seawater desalination system according to claim 1, characterized in that: The thermal film coupled seawater desalination system further includes: a first clear water tank, wherein the first clear water tank is connected to the second input end of the multiple-effect distillation evaporator.

7. The thermal film coupled seawater desalination system according to claim 1, characterized in that: The thermal membrane coupled seawater desalination system further includes: a second clear water tank, wherein the second clear water tank is connected to the input end of the filtering device.

8. The thermal film coupled seawater desalination system according to claim 7, characterized in that: If the current seawater temperature is lower than the preset temperature threshold, the water heated by heat exchange in the multi-effect distillation condenser is returned to the second clear water tank.

9. A seawater coupling method based on the thermal film coupled seawater desalination system according to any one of claims 1 to 8, characterized in that: include: The seawater is divided into two routes, one of which is transported to the multi-effect distillation evaporator, and the other is filtered by the filter device and then transported to the seawater reverse osmosis system; part of the seawater reverse osmosis water produced by the seawater reverse osmosis system is transported to the fresh water reverse osmosis system; The hot water from the power plant is transported to the multiple-effect distillation evaporator after passing through the flash tank, and the seawater is transported to the multiple-effect distillation condenser after absorbing heat in the multiple-effect distillation evaporator; According to the current seawater temperature, it is determined whether the other part of the seawater reverse osmosis water of the seawater reverse osmosis system and the freshwater reverse osmosis water of the freshwater reverse osmosis system are output to the pure water tank or the multi-effect distillation condenser.

10. The seawater coupling method according to claim 9, characterized in that: If the current seawater temperature is lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are directly transported to the pure water tank according to the current seawater temperature; If the current seawater temperature is not lower than the preset temperature threshold, the other part of the seawater reverse osmosis water produced by the seawater reverse osmosis system and the freshwater reverse osmosis water produced by the freshwater reverse osmosis system are both transported to the multi-effect distillation condenser according to the current seawater temperature, and the produced water condensed by the multi-effect distillation condenser enters the pure water tank.

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