Membrane desalination water treatment device

Abstract

The application provides a membrane desalination water treatment device, industrial clean water is preheated through a preheating system, the preheating system comprises a heating heat exchanger, a heat pump and a cooling heat exchanger, the heat pump and the cooling heat exchanger are further provided with a first bypass pipeline and a second bypass pipeline in parallel, and under the premise that the temperature of the industrial clean water is less than the design water temperature of a reverse osmosis system: when the return water temperature of a cooling water system is less than a first set threshold, the heat pump and the cooling heat exchanger work, and the first bypass pipeline and the second bypass pipeline are disconnected; when the return water temperature is greater than the first set threshold and a direct heating coefficient is greater than a second set threshold, the heat pump and the cooling heat exchanger work, and the first bypass pipeline and the second bypass pipeline are disconnected; when the return water temperature is greater than the first set threshold, and the direct heating coefficient is less than the second set threshold, the first bypass pipeline and the second bypass pipeline are turned on, and the heat pump and the cooling heat exchanger are disabled. The whole process does not need external steam heat sources and other high-temperature heat sources.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a membrane desalination treatment device. Background Technology

[0002] Desalinated water is water in which salt ions have been removed from the raw water, and it is widely used in industrial fields. Desalinated water is produced by purifying and desalinating industrial purified water, often using a membrane method.

[0003] The conventional membrane-based water treatment process flow is as follows: industrial water purification → filtration → heat exchange → ultrafiltration → reverse osmosis.

[0004] The purpose of filtration is to remove suspended solids and colloidal organic matter from the water, further reducing turbidity to ensure stable operation of the subsequent ultrafiltration unit. The filtered water enters the heat exchanger using residual pressure, with steam as the heat medium, to ensure a stable water temperature of around 20°C in winter, thus ensuring stable and safe operation of the subsequent ultrafiltration and reverse osmosis systems.

[0005] Ultrafiltration (UF) systems utilize hollow fiber membrane separation technology, a novel purification and separation technology. Before reverse osmosis, UF membrane separation thoroughly removes colloids, bacteria, microorganisms, and suspended solids from the water, significantly reducing the TSS (Total Susceptibility Saturation) and SDI (Soil Degradation Index) of the effluent. This greatly reduces the cleaning frequency of the subsequent reverse osmosis system, improving production efficiency and reducing wastewater discharge, energy consumption, and chemical consumption. Reverse osmosis systems primarily remove dissolved salts from the water, while also removing some large organic molecules and small particles not removed in the previous stage. Under pressure, most water molecules and trace amounts of other ions permeate through the reverse osmosis membrane, are collected as product water, and enter subsequent equipment through the product water pipeline. Most of the salts, colloids, and organic matter in the water cannot permeate through the reverse osmosis membrane and remain in a small amount of concentrate, which is discharged through the concentrate pipeline.

[0006] The membrane desalination equipment currently used requires the discharge of concentrated water and a large amount of steam as a heat source for heat exchange in winter, which has the disadvantages of high water consumption, high energy consumption and environmental unfriendliness. Summary of the Invention

[0007] The purpose of this invention is to provide a membrane desalination water treatment device that solves the problems of high water consumption and high energy consumption in existing membrane desalination water treatment devices, which require a large amount of steam as a heat source for heat exchange in winter.

[0008] To achieve the above objectives, the present invention provides a membrane desalination water treatment device for desalinating industrial purified water, comprising a pretreatment system, a preheating system, an ultrafiltration system, and a reverse osmosis system connected in sequence.

[0009] The preheating system includes a heating heat exchanger, a heat pump, and a cooling heat exchanger. The heating side inlet of the heating heat exchanger is connected to the outlet of the pretreatment system. The heating side outlet of the heating heat exchanger is connected to the inlet of the ultrafiltration system. The heat exchange side inlet of the heating heat exchanger is connected to the heat medium outlet of the heat pump via a heat medium supply pipeline. The heat exchange side outlet of the heating heat exchanger is connected to the heat exchange side inlet of the cooling heat exchanger via a heat medium return pipeline. The heat exchange side outlet of the cooling heat exchanger is connected to the supply of a factory's cooling water system. The heat medium inlet of the heat pump is connected to the return of the cooling water system.

[0010] The refrigerant inlet of the heat pump is connected to the outlet of the cooling heat exchanger on the heating side through a refrigerant return water pipeline, and the refrigerant outlet of the heat pump is connected to the inlet of the cooling heat exchanger on the heating side through a refrigerant supply water pipeline.

[0011] The heat pump and the cooling heat exchanger are also respectively provided with a first bypass pipe and a second bypass pipe in parallel. The inlet end of the first bypass pipe is connected to the return end of the cooling water system, the outlet end of the first bypass pipe is connected to the heat medium supply pipe, the inlet end of the second bypass pipe is connected to the heat medium return pipe, and the outlet end of the second bypass pipe is connected to the supply end of the cooling water system.

[0012] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is lower than the first set threshold, the heat pump and the cooling heat exchanger operate, and the first bypass pipeline and the second bypass pipeline are disconnected.

[0013] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is greater than the first set threshold, and the direct heating coefficient is greater than the second set threshold, the heat pump and the cooling heat exchanger operate, and the first bypass pipeline and the second bypass pipeline are disconnected.

[0014] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is greater than the first set threshold, and the direct heating coefficient is less than the second set threshold, the first bypass pipeline and the second bypass pipeline are connected, and the heat pump and the cooling heat exchanger are shut down.

[0015] The direct heating coefficient is the ratio of the heat required to heat the industrial purified water to the design water temperature of the reverse osmosis system to the heat generated by the supply and return water of the cooling water system.

[0016] Optionally, the design water temperature of the reverse osmosis system is between 24.5℃ and 25.5℃.

[0017] Optionally, the first set threshold is not less than 30°C, and the second set threshold is not less than 0.8°C.

[0018] Optionally, the heating heat exchanger is also provided with a third bypass pipeline in parallel, the inlet of the third bypass pipeline is connected to the outlet of the pretreatment system, and the outlet of the third bypass pipeline is connected to the inlet of the ultrafiltration system.

[0019] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system, the third bypass pipe is disconnected and the preheating system operates; when the temperature of the industrial purified water is higher than or equal to the design water temperature of the reverse osmosis system, the third bypass pipe is connected and the preheating system is shut down.

[0020] Optionally, a first shut-off valve and a second shut-off valve are respectively provided between the heating heat exchanger and the pretreatment system and the ultrafiltration system, and a third shut-off valve is provided on the third bypass pipeline.

[0021] Optionally, the first shut-off valve is an automatic control valve, the second shut-off valve is a check valve, and the third shut-off valve is a pressure relief valve.

[0022] Optionally, a first water supply pump is provided between the heat exchange side outlet of the cooling heat exchanger and the water supply end of the cooling water system, and a second water supply pump is provided on the refrigerant water supply pipeline.

[0023] Optionally, a fourth shut-off valve is provided on the first bypass pipeline, and a fifth shut-off valve is provided on the second bypass pipeline.

[0024] Optionally, the product water of the reverse osmosis system is demineralized water, and the concentrate of the reverse osmosis system is directly used as makeup water for the circulating water tank of the cooling water system. The makeup water volume is calculated by multiplying the flow difference between the main supply pipe and the main return pipe of the cooling water system by a replenishment coefficient, which is the ratio of the conductivity of the circulating water to the conductivity of the concentrate in the cooling water system.

[0025] Optionally, the concentrate pipeline of the reverse osmosis system is directly connected to the return water main of the cooling water system, and the return water main is also equipped with a pipeline static mixer.

[0026] The membrane desalination treatment device provided by the present invention has at least one of the following beneficial effects:

[0027] 1) When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is lower than the first set threshold, the heat pump and the cooling heat exchanger operate. The return water of the cooling water system is heated by the heat pump and then enters the heat exchange side of the heating heat exchanger. After the heating heat exchanger heats the effluent of the pretreatment system, it is sent to the ultrafiltration system. Throughout the process, the heat pump forces heat from the low-temperature medium to the high-temperature medium in a reverse circulation manner. Only a small amount of reverse circulation net work is consumed to obtain a large amount of heat supply. This effectively utilizes the low-grade heat energy of the cooling water system without the need for external steam heat sources or other high-temperature hot water heat sources, thereby achieving energy saving. Furthermore, since only a very small portion of the external cooling water is used, it will not have any impact on the original cooling water system.

[0028] 2) When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is higher than the first set threshold, and the direct heating coefficient is higher than the second set threshold, the heat pump and the cooling heat exchanger operate, and the first bypass pipeline and the second bypass pipeline are disconnected. The direct heating coefficient is the ratio of the heat required to raise the temperature of the industrial purified water to the design water temperature of the reverse osmosis system to the heat generated by the supply and return water of the cooling water system. Since there is a temperature difference between the supply and return water of the cooling water system, when the temperature difference between the supply and return water and the heat generated by the circulation are insufficient to raise the temperature of the industrial purified water to a level not lower than the design water temperature of the reverse osmosis system, the heat pump and the cooling heat exchanger operate, and their preheating process refers to the preheating process when the return water temperature of the cooling water system is lower than the first set threshold.

[0029] 2) When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is higher than the first set threshold, the heat pump is not required for heating. Therefore, the heat pump and the cooling heat exchanger do not need to operate. By opening the first bypass pipe and the second bypass pipe, the supply and return water of the cooling water system can form a circulation loop on the heat exchange side of the heating heat exchanger to heat the effluent of the pretreatment system and send it into the ultrafiltration system. This process also does not require an external steam heat source or other high-temperature hot water heat sources, achieving energy saving. Furthermore, it will not have any impact on the original cooling water system.

[0030] 3) When the temperature of the industrial purified water is higher than or equal to the design water temperature of the reverse osmosis system, it is not necessary to heat the industrial purified water. The effluent from the pretreatment system directly enters the ultrafiltration system from the third bypass pipeline, and the preheating system is shut down.

[0031] 4) The concentrate from the reverse osmosis system is used as makeup water for the circulating water tank of the cooling water system. The amount of makeup water is calculated by multiplying the flow difference between the main supply pipe and the main return pipe of the cooling water system by a replenishment coefficient. The replenishment coefficient is the ratio of the conductivity of the circulating water to the conductivity of the concentrate in the cooling water system. This enables the reuse of concentrate, reduces the discharge of concentrate, and is beneficial to environmental protection. Attached Figure Description

[0032] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0033] Figure 1 This is a schematic diagram of a membrane desalination treatment device provided in an embodiment of the present invention.

[0034] In the attached image:

[0035] 10-Pretreatment system; 20-Preheating system; 21-Heating heat exchanger; 22-Heat pump; 23-Cooling heat exchanger; 24-Heating medium supply pipeline; 25-Heating medium return pipeline; 26-Cooling medium return pipeline; 27-Cooling medium supply pipeline; 30-Ultrafiltration system; 40-Reverse osmosis system; 51-First bypass pipeline; 52-Second bypass pipeline; 53-Third bypass pipeline; 61-First water supply pump; 62-Second water supply pump; 71-First shut-off valve; 72-Second shut-off valve; 73-Third shut-off valve; 74-Fourth shut-off valve; 75-Fifth shut-off valve; 80-Circulating water tank. Detailed Implementation

[0036] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the purpose of the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only used to complement the content disclosed in the specification, for those skilled in the art to understand and read, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, if they are the same as or similar to the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0037] As used herein, the singular forms “a,” “an,” and “the” include plural objects unless otherwise expressly indicated. As used herein, the term “or” is generally used to include “and / or” unless otherwise expressly indicated. As used herein, the term “a number” is generally used to include “at least one” unless otherwise expressly indicated. As used herein, the term “at least two” is generally used to include “two or more” unless otherwise expressly indicated. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature.

[0038] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a membrane desalination treatment device according to an embodiment of the present invention. This embodiment provides a membrane desalination treatment device for desalinating industrial purified water, comprising a pretreatment system 10, a preheating system 20, an ultrafiltration system 30, and a reverse osmosis system 40 connected in sequence.

[0040] The preheating system 20 includes a heating heat exchanger 21, a heat pump 22, and a cooling heat exchanger 23. The heating side inlet of the heating heat exchanger 21 is connected to the outlet of the pretreatment system 10. The heating side outlet of the heating heat exchanger 21 is connected to the inlet of the ultrafiltration system 30. The heat exchange side inlet of the heating heat exchanger 21 is connected to the heat medium outlet of the heat pump 22 via a heat medium supply pipeline 24. The heat exchange side outlet of the heating heat exchanger 21 is connected to the heat exchange side inlet of the cooling heat exchanger 23 via a heat medium return pipeline 25. The heat exchange side outlet of the cooling heat exchanger 23 is connected to the supply end of a factory's cooling water system. The heat medium inlet of the heat pump 22 is connected to the return end of the cooling water system.

[0041] The refrigerant inlet of the heat pump 22 is connected to the heating side outlet of the cooling heat exchanger 23 through a refrigerant return water pipe 26, and the refrigerant outlet of the heat pump 22 is connected to the heating side inlet of the cooling heat exchanger 23 through a refrigerant supply water pipe 27.

[0042] The heat pump 22 and the cooling heat exchanger 23 are also respectively provided with a first bypass pipe 51 and a second bypass pipe 52 in parallel. The inlet end of the first bypass pipe 51 is connected to the return end of the cooling water system, the outlet end of the first bypass pipe 51 is connected to the heat medium supply pipe 24, the inlet end of the second bypass pipe 52 is connected to the heat medium return pipe 25, and the outlet end of the second bypass pipe 52 is connected to the supply end of the cooling water system.

[0043] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water temperature of the cooling water system is lower than the first set threshold, the heat pump 22 and the cooling heat exchanger 23 operate, and the first bypass pipe 51 and the second bypass pipe 52 are disconnected.

[0044] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water temperature of the cooling water system is greater than the first set threshold, and the direct heating coefficient is greater than the second set threshold, the heat pump 22 and the cooling heat exchanger 23 operate, and the first bypass pipe 51 and the second bypass pipe 52 are disconnected.

[0045] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water temperature of the cooling water system is greater than the first set threshold, and the direct heating coefficient is less than the second set threshold, the first bypass pipe 51 and the second bypass pipe 52 are connected, and the heat pump 22 and the cooling heat exchanger 23 are deactivated.

[0046] The direct heating coefficient is the ratio of the heat required to heat the industrial purified water to the design water temperature of the reverse osmosis system 40 to the heat generated by the supply and return water of the cooling water system.

[0047] The working principle of this invention is as follows:

[0048] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40, typically in winter, preheating is required to ensure the stable and safe operation of the subsequent ultrafiltration system 30 and reverse osmosis system 40, so that the temperature of the industrial purified water is not lower than the design water temperature of the reverse osmosis system 40. Simultaneously, the return water temperature of the cooling water system needs further monitoring. When the return water temperature of the cooling water system is lower than a first set threshold, the heat pump 22 and the cooling heat exchanger 23 operate, and the first bypass pipe 51 and the second bypass pipe 52 are disconnected. The return water from the cooling water system, heated by the heat pump 22, enters the heat exchange side of the heating heat exchanger 21. The heat exchanger 21 then heats the effluent from the pretreatment system 10 before sending it to the ultrafiltration system 30. Simultaneously, the effluent from the heat exchanger 21 enters the inlet of the cooling heat exchanger 23 via the heat medium return pipe 25. After being cooled by the cooling heat exchanger 23, it returns to the cooling water system. Throughout this process, the heat pump 22 forces heat from the low-temperature medium to the high-temperature medium in a reverse circulation manner, consuming only a small amount of net reverse circulation work while achieving a large heat supply. This effectively utilizes the low-grade heat energy of the cooling water system without requiring external steam or other high-temperature hot water sources, thus achieving energy savings. Furthermore, since only a very small portion of the external cooling water is used, it has no impact on the original cooling water system.

[0049] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water temperature of the cooling water system is higher than the first set threshold, and the direct heating coefficient is higher than the second set threshold, the heat pump 22 and the cooling heat exchanger 23 operate, and the first bypass pipe 51 and the second bypass pipe 52 are disconnected. The direct heating coefficient is the ratio of the heat required to raise the temperature of the industrial purified water to the design water temperature of the reverse osmosis system 40 to the heat generated by the supply and return water of the cooling water system. Since there is a temperature difference between the supply and return water of the cooling water system, when the temperature difference between the supply and return water and the heat generated by the circulation are insufficient to raise the temperature of the industrial purified water to a level not lower than the design water temperature of the reverse osmosis system 40, the heat pump 22 and the cooling heat exchanger 23 operate, and their preheating process refers to the preheating process when the return water temperature of the cooling water system is lower than the first set threshold.

[0050] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water of the cooling water system is higher than the first set threshold, and the direct heating coefficient is lower than the second set threshold, it indicates that the temperature difference between the return water and the supply water, and the heat generated by the circulation, are sufficient to raise the temperature of the industrial purified water to no lower than the design water temperature of the reverse osmosis system 40. In this case, the heat pump 22 is not required for heating, so the heat pump 22 and the cooling heat exchanger 23 do not need to operate. By opening the first bypass pipe 51 and the second bypass pipe 52, the supply and return water of the cooling water system can form a circulation loop on the heat exchange side of the heating heat exchanger 21 to heat the effluent of the pretreatment system 10 and send it into the ultrafiltration system 30. This process also does not require an external steam heat source or other high-temperature hot water heat sources, achieving energy saving. Furthermore, it will not have any impact on the original cooling water system.

[0051] It should be understood that the "cooling water system" mentioned in this application refers to the factory's existing industrial cooling water system, which is not protected or limited in this application.

[0052] In this embodiment, conventional heat exchangers can be used for the heating heat exchanger 21 and the cooling heat exchanger 23.

[0053] In this embodiment, the design water temperature of the reverse osmosis system 40 is between 24.5℃ and 25.5℃. The design water temperature can be adjusted according to the actual situation, and this application does not limit it.

[0054] Preferably, the first set threshold is not less than 30°C, and the second set threshold is not less than 0.8°C.

[0055] Preferably, a first water supply pump 61 is provided between the heat exchange side outlet of the cooling heat exchanger 23 and the water supply end of the cooling water system, and the water from the heat exchange side outlet of the cooling heat exchanger 23 is pressurized by the first water supply pump 61 and then supplied to the cooling water system.

[0056] Preferably, a second water supply pump 62 is provided on the refrigerant supply pipeline 27, and the refrigerant outlet water of the heat pump 22 is pressurized by the second water supply pump 62 and enters the heating side water inlet of the cooling heat exchanger 23.

[0057] In this embodiment, a fourth shut-off valve 74 is provided on the first bypass pipeline 51, and the fourth shut-off valve 74 is used to control the opening and closing of the first bypass pipeline 51.

[0058] In this embodiment, a fifth shut-off valve 75 is provided on the second bypass pipeline 52, and the fifth shut-off valve 75 is used to control the opening and closing of the second bypass pipeline 52.

[0059] Preferably, the heating heat exchanger 21 is also provided with a third bypass pipe 53 in parallel, the inlet end of the third bypass pipe 53 is connected to the outlet end of the pretreatment system 10, and the outlet end of the third bypass pipe 53 is connected to the inlet end of the ultrafiltration system 30.

[0060] When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40, the third bypass pipe 53 is disconnected and the preheating system 20 is activated; when the temperature of the industrial purified water is higher than or equal to the design water temperature of the reverse osmosis system 40, the third bypass pipe 53 is activated and the preheating system 20 is deactivated.

[0061] In other words, when the temperature of the industrial purified water is higher than or equal to the design water temperature of the reverse osmosis system 40, which usually occurs outside of winter, there is no need to heat the industrial purified water. The effluent from the pretreatment system 10 directly enters the ultrafiltration system 30 from the third bypass pipe 53, and the preheating system 20 is shut down.

[0062] In this embodiment, a first shut-off valve 71 and a second shut-off valve 72 are respectively provided between the heating heat exchanger 21, the pretreatment system 10, and the ultrafiltration system 30, and a third shut-off valve 73 is provided on the third bypass pipeline 53.

[0063] Preferably, the first shut-off valve 71 is an automatic control valve, the second shut-off valve 72 is a check valve, and the third shut-off valve 73 is a pressure relief valve. When the first shut-off valve 71 is closed, the inlet water pressure on the third bypass pipeline 53 will increase, allowing water to flow out through the third shut-off valve 73; therefore, the third shut-off valve 73 does not require separate control. Simultaneously, the second shut-off valve 72 is a check valve to prevent backflow and also does not require separate control. Therefore, switching between the third bypass pipeline 53 and the preheating system 20 can be achieved simply by controlling the first shut-off valve 71, resulting in a high degree of automation.

[0064] Preferably, the product water of the reverse osmosis system 40 is demineralized water, and the concentrate of the reverse osmosis system 40 can be directly used as makeup water for the circulating water tank 80 of the cooling water system. The makeup water volume is calculated by multiplying the flow difference between the main supply pipe and the main return pipe of the cooling water system by a replenishment coefficient. The replenishment coefficient is the ratio of the conductivity of the circulating water to the conductivity of the concentrate in the cooling water system. This achieves the reuse of concentrate, reduces the discharge of concentrate, and is beneficial to environmental protection.

[0065] The flow rate of the main supply pipe of the cooling water system can be measured by a flow meter installed on the main supply pipe, and the flow rate of the main return pipe of the cooling water system can be measured by a flow meter installed on the main return pipe.

[0066] Preferably, the concentrate pipeline of the reverse osmosis system 40 is directly connected to the return water main of the cooling water system. The return water main is also equipped with a pipeline static mixer so that the concentrate from the concentrate pipeline can be fully mixed with the return water of the circulating cooling water after entering the pipeline static mixer.

[0067] The membrane desalination treatment device provided in this embodiment of the invention has the following three operating states:

[0068] 1) When the temperature of the industrial purified water is higher than or equal to the design water temperature of the reverse osmosis system 40, the third shut-off valve 73 is opened, the first shut-off valve 71 and the second shut-off valve 72 are disconnected, the third bypass pipeline 53 is connected, and the preheating system 20 is shut down.

[0069] 2) When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water temperature of the cooling water system is lower than the first set threshold, or when the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water temperature of the cooling water system is higher than the first set threshold, and the direct heating coefficient is higher than the second set threshold, the third shut-off valve 73, the fourth shut-off valve 74 and the fifth shut-off valve 75 are disconnected, the first shut-off valve 71 and the second shut-off valve 72 are opened, the heat pump 22 and the cooling heat exchanger 23 are operated, and the first bypass pipeline 51 and the second bypass pipeline 52 are disconnected.

[0070] 3) When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system 40 and the return water of the cooling water system is greater than the first set threshold, and the direct heating coefficient is less than the second set threshold, the third shut-off valve 73 is disconnected, the first shut-off valve 71, the second shut-off valve 72, the fourth shut-off valve 74 and the fifth shut-off valve 75 are opened, the first bypass pipeline 51 and the second bypass pipeline 52 are connected, and the heat pump 22 and the cooling heat exchanger 23 are shut down.

[0071] In summary, this invention provides a membrane-based desalination water treatment device. Based on whether the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system, whether the return water temperature of the cooling water system is lower than a first set threshold, and whether the direct heating coefficient is lower than a second set threshold, the device selects whether preheating is required and whether a heat pump is needed. The heating process requires no external steam heat source or other high-temperature hot water heat source, achieving energy savings. Furthermore, it does not affect the existing cooling water system.

[0072] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure are within the protection scope of the present invention. Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A membrane desalination water treatment device for desalinating industrial purified water, characterized in that, It includes a pretreatment system, a preheating system, an ultrafiltration system, and a reverse osmosis system connected in sequence; The preheating system includes a heating heat exchanger, a heat pump, and a cooling heat exchanger. The heating side inlet of the heating heat exchanger is connected to the outlet of the pretreatment system. The heating side outlet of the heating heat exchanger is connected to the inlet of the ultrafiltration system. The heat exchange side inlet of the heating heat exchanger is connected to the heat medium outlet of the heat pump via a heat medium supply pipeline. The heat exchange side outlet of the heating heat exchanger is connected to the heat exchange side inlet of the cooling heat exchanger via a heat medium return pipeline. The heat exchange side outlet of the cooling heat exchanger is connected to the supply of a factory's cooling water system. The heat medium inlet of the heat pump is connected to the return of the cooling water system. The refrigerant inlet of the heat pump is connected to the outlet of the cooling heat exchanger on the heating side through a refrigerant return water pipeline, and the refrigerant outlet of the heat pump is connected to the inlet of the cooling heat exchanger on the heating side through a refrigerant supply water pipeline. The heat pump and the cooling heat exchanger are also respectively provided with a first bypass pipe and a second bypass pipe in parallel. The inlet end of the first bypass pipe is connected to the return end of the cooling water system, the outlet end of the first bypass pipe is connected to the heat medium supply pipe, the inlet end of the second bypass pipe is connected to the heat medium return pipe, and the outlet end of the second bypass pipe is connected to the supply end of the cooling water system. The membrane desalination treatment device operates as follows: When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is lower than the first set threshold, the heat pump and the cooling heat exchanger operate, and the first bypass pipeline and the second bypass pipeline are disconnected. When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is greater than the first set threshold, and the direct heating coefficient is greater than the second set threshold, the heat pump and the cooling heat exchanger operate, and the first bypass pipeline and the second bypass pipeline are disconnected. When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system and the return water temperature of the cooling water system is greater than the first set threshold, and the direct heating coefficient is less than the second set threshold, the first bypass pipeline and the second bypass pipeline are connected, and the heat pump and the cooling heat exchanger are shut down. The direct heating coefficient is the ratio of the heat required to heat the industrial purified water to the design water temperature of the reverse osmosis system to the heat generated by the supply and return water of the cooling water system.

2. The membrane desalination treatment device according to claim 1, characterized in that, The design water temperature of the reverse osmosis system is between 24.5℃ and 25.5℃.

3. The membrane desalination treatment device according to claim 1 or 2, characterized in that, The first set threshold is not less than 30°C, and the second set threshold is not less than 0.8°C.

4. The membrane desalination treatment device according to claim 1, characterized in that, The heating heat exchanger is also provided with a third bypass pipeline in parallel. The inlet end of the third bypass pipeline is connected to the outlet end of the pretreatment system, and the outlet end of the third bypass pipeline is connected to the inlet end of the ultrafiltration system. When the temperature of the industrial purified water is lower than the design water temperature of the reverse osmosis system, the third bypass pipe is disconnected and the preheating system operates; when the temperature of the industrial purified water is higher than or equal to the design water temperature of the reverse osmosis system, the third bypass pipe is connected and the preheating system is shut down.

5. The membrane desalination treatment device according to claim 4, characterized in that, A first shut-off valve and a second shut-off valve are respectively provided between the heating heat exchanger and the pretreatment system and the ultrafiltration system, and a third shut-off valve is provided on the third bypass pipeline.

6. The membrane desalination treatment device according to claim 5, characterized in that, The first shut-off valve is an automatic control valve, the second shut-off valve is a check valve, and the third shut-off valve is a pressure relief valve.

7. The membrane desalination treatment device according to claim 1, characterized in that, A first water supply pump is installed between the heat exchange side outlet of the cooling heat exchanger and the water supply end of the cooling water system, and a second water supply pump is installed on the refrigerant water supply pipeline.

8. The membrane desalination treatment device according to claim 1, characterized in that, A fourth shut-off valve is installed on the first bypass pipeline, and a fifth shut-off valve is installed on the second bypass pipeline.

9. The membrane desalination treatment device according to claim 1, characterized in that, The product water of the reverse osmosis system is demineralized water, and the concentrate of the reverse osmosis system is directly used as makeup water for the circulating water tank of the cooling water system. The makeup water volume is calculated by multiplying the flow difference between the main supply pipe and the main return pipe of the cooling water system by a replenishment coefficient, which is the ratio of the conductivity of the circulating water to the conductivity of the concentrate in the cooling water system.

10. The membrane desalination treatment apparatus according to claim 9, characterized in that, The concentrate pipeline of the reverse osmosis system is directly connected to the return water main of the cooling water system, and a static mixer is also installed on the return water main.

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