Water purification process based on pervaporation desalination technology

Abstract

The invention discloses a water purification process based on a pervaporation desalination technology, which comprises the following steps: firstly, raw water is guided to a raw water buffer tank, and water quality parameters are monitored through built-in conductivity, temperature and liquid level sensors; secondly, the circulation of raw water in the system is realized by utilizing a raw water circulating pump; then, the raw water is preheated by a shell pass of the pre-condenser and then is fed into a hot-end heat exchanger of the heating and condensing coupler to be heated; then, the heated raw water enters a pervaporation desalination membrane element to complete a pervaporation process, concentrated water returns to the raw water buffer tank to continue to circulate, and the raw water becomes steam under the action of a vacuum pump and enters a tube pass of a pre-condenser to be primarily condensed; then, the primarily condensed water vapor is further condensed by heating a cold end heat exchanger of the condensation coupler; finally, purified water formed by condensation is collected in a produced water storage tank; the process can effectively remove salt in water and improve the utilization rate of water resources.

Description

Technical Field

[0001] The invention relates to a water purification process, in particular to a water purification process based on pervaporation desalination technology. Background Art

[0002] With the rapid development of industry and social progress, the demand for high-quality pure water in all walks of life is growing, especially in the fields of semiconductors, electronics, medicine, chemicals, coal-fired power generation, etc. Pure water is an important cleaning fluid, and its purity directly affects product quality and production efficiency.

[0003] Traditional pure water preparation equipment usually adopts a complex process route that combines multiple methods, including pretreatment, reverse osmosis technology, purification treatment, and post-treatment. Its purpose is to remove various impurities such as conductive media, colloids, gases and organic matter in water, so that the water quality reaches an extremely low impurity content and meets the stringent requirements for pure water purity in different fields.

[0004] Among them, the pretreatment stage usually includes filtration, flocculation, ion exchange and other steps, aiming to remove large particle impurities, colloids and ions in the raw water, and provide high-quality raw water for subsequent reverse osmosis. Reverse osmosis is the core process of pure water preparation. By pressurizing raw water through a semipermeable membrane, it can effectively separate and remove dissolved solids and some organic matter with smaller molecular weight in the water. Purification treatment uses technologies such as mixed bed or electrodialysis to further reduce the conductivity of the water. Finally, the post-treatment uses ultraviolet disinfection or ultrafiltration membranes to remove residual bacteria and large molecular organic matter.

[0005] However, the existing pure water preparation technology has many shortcomings. First, the process route is long and complicated, requiring multiple steps to cooperate and cumbersome operation. Second, the energy consumption is high, especially the reverse osmosis stage requires a high-pressure pump to pressurize the raw water, resulting in high energy consumption. Third, the preparation process will produce a large amount of concentrated water discharge, which contains a certain concentration of dissolved substances, which not only causes a waste of resources, but also increases the cost and burden of subsequent wastewater treatment. In addition, in order to ensure the long-term stable operation of the membrane, the raw water needs to be pretreated in a complex manner to remove large particles of impurities, organic matter, etc., which increases the operating cost of the pretreatment.

[0006] Therefore, the existing technology has obvious shortcomings in terms of complex process, high energy consumption, large amount of concentrated water discharge and complex pretreatment, and urgently needs improvement and innovation. Developing a new method for preparing pure water with simpler process, lower energy consumption and no concentrated water discharge will help reduce operating costs, reduce energy consumption and environmental pollution, and promote the sustainable development of the pure water industry. Summary of the invention

[0007] The purpose of the present invention is to provide a water purification process based on pervaporation desalination technology, which can simplify the process flow, reduce energy consumption, and reduce concentrated water discharge, thereby achieving efficient and energy-saving pure water preparation.

[0008] To achieve the above object, the present invention provides the following technical solution: a water purification process based on pervaporation desalination technology, comprising the following steps:

[0009] S1, water intake step: introducing raw water into a raw water buffer tank, and monitoring the water quality, temperature and liquid level of the raw water respectively through a conductivity sensor, a temperature sensor and a liquid level sensor arranged in the raw water buffer tank;

[0010] S2, raw water circulation step: pumping out the raw water in the raw water buffer tank through the raw water circulation pump, so that the raw water circulates in the system;

[0011] S4, heating step: transporting the raw water to the shell side of the pre-condenser, and then transporting the raw water passing through the shell side of the pre-condenser to the hot end heat exchanger of the heating condensation coupler for heating;

[0012] S5, pervaporation step: the heated raw water is transported to the pervaporation desalination membrane element for pervaporation treatment, and the concentrated water after treatment is returned to the raw water buffer tank to form a cycle. At the same time, under the action of the vacuum pump, the water vapor that permeates the membrane enters the tube side of the pre-condenser through the vacuum pipeline;

[0013] S6, condensation collection step: after the water vapor is pre-condensed in the tube of the pre-condenser, it enters the cold end heat exchanger of the heating condensation coupler for further condensation;

[0014] S7, produced water collection step: collect the condensed pure water into a produced water storage tank, and monitor the purity of the produced water by a conductivity sensor or a resistance sensor arranged in the produced water storage tank.

[0015] Furthermore, step S1 also includes the following preprocessing steps:

[0016] S11, water quality monitoring step of the raw water buffer tank: monitor the water quality of the raw water buffer tank in real time through a conductivity sensor, and when the conductivity of the water in the buffer tank exceeds a preset range, discharge it through a first vent valve;

[0017] S12, raw water buffer tank water temperature adjustment step: monitor the water temperature of the raw water buffer tank in real time through a temperature sensor, and when the water temperature is lower than a preset temperature, start the built-in heater for heating; when the water temperature is higher than the preset temperature, turn off the heater;

[0018] S13, raw water level control step: monitor the raw water level in real time through the level sensor, when the raw water level is lower than the minimum level, start water replenishment, when the raw water level reaches the maximum level, stop water intake.

[0019] Furthermore, step S4 also includes the following heating control step:

[0020] S41, monitoring the inlet temperature and outlet temperature of the heat exchanger at the hot end of the heating condensing coupler;

[0021] S42. Adjust the heating power according to the outlet temperature. When the outlet temperature is lower than the set value, increase the heating power; when the outlet temperature is higher than the set value, reduce the heating power.

[0022] Furthermore, step S5 also includes the following pervaporation process control steps:

[0023] S51, pervaporation desalination membrane element pressure difference monitoring:

[0024] a. Install a vacuum pressure sensor on the permeate side of the pervaporation desalination membrane element to monitor the permeate side pressure P in real time;

[0025] b. When the pressure difference P does not meet the preset range, an alarm will be sounded and corresponding adjustments will be made;

[0026] S52, permeation flux monitoring of pervaporation desalination membrane elements:

[0027] a. Install a flow meter at the water production end of the pervaporation desalination membrane element to measure the permeate water volume V per unit time;

[0028] b. Record the effective membrane area A of the pervaporation desalination membrane element;

[0029] c. Calculate the permeation flux per unit time and per unit area J = V / (A·t);

[0030] d. Establish the relationship curve between permeation flux J and operation time t;

[0031] e. When the permeate flux drops by more than 20%, the pervaporation desalination membrane element is cleaned;

[0032] S53, Analysis of separation efficiency of pervaporation desalination membrane elements:

[0033] a. Install conductivity sensor EC1 at the water inlet of the pervaporation desalination membrane element to measure the conductivity of the inlet water;

[0034] b. Install conductivity sensor EC2 at the water production end of the pervaporation desalination membrane element to measure the conductivity of the produced water;

[0035] c. Calculate the desalination rate R = (EC1-EC2) / EC1×100%;

[0036] d. When the desalination rate is lower than the set value, adjust the operating parameters or perform membrane element maintenance.

[0037] Furthermore, step S6 also includes the steps of temperature monitoring and recording.

[0038] Install temperature sensor T1 at the inlet of the pre-condenser tube to monitor the water vapor inlet temperature;

[0039] Install temperature sensor T2 at the outlet of the pre-condenser tube to monitor the outlet temperature of the pre-condensed water;

[0040] Install temperature sensor T3 at the shell inlet of the pre-condenser to monitor the cooling water inlet temperature;

[0041] A temperature sensor T4 is installed at the shell outlet of the pre-condenser to monitor the cooling water outlet temperature.

[0042] Furthermore, after step S7, a resin adsorption step S8 is also included: the condensed pure water portion is sent to a resin adsorption column, the resin is a polishing resin, and the resin adsorption column is used to further remove ionic impurities in the water, thereby preparing ultrapure water, and the prepared ultrapure water is sent to another water production storage tank.

[0043] Furthermore, the heating and condensing coupler is in one of the following two forms: a heating and condensing device based on multiple semiconductor refrigeration plates connected in series or in parallel, wherein the hot end of the semiconductor refrigeration plate is used to heat raw water and the cold end is used to condense produced water; or a refrigeration compressor, wherein the condensing end is used to heat raw water and the evaporating end is used to condense produced water.

[0044] Furthermore, the raw water buffer tank and the produced water storage tank are both thermal insulation type storage tanks, and the pipelines connecting the various components are made of thermal insulation materials or coated with thermal insulation layers.

[0045] Furthermore, the pervaporation desalination membrane element is a hydrophilic pervaporation desalination membrane or a reverse osmosis membrane with a desalination rate greater than 99.5%, and the membrane assembly is in the form of a roll membrane or a hollow fiber column membrane.

[0046] Compared with the prior art, the advantages of the present invention are: the water purification system realizes an efficient water purification process through the coordinated work of multiple components. The working principle of the system is as follows: the raw water first enters the buffer tank and is then driven by the circulating pump to flow in the system. After the raw water undergoes preliminary heat exchange in the shell side of the pre-condenser, it enters the hot end heat exchanger of the heating condensing coupler for further heating. The heated raw water enters the pervaporation desalination membrane element, where the pervaporation process occurs, and the water vapor passes through the membrane into the vacuum side. The water vapor then enters the tube side of the pre-condenser for preliminary condensation, and then is completely condensed into liquid water in the cold end heat exchanger of the heating condensing coupler, and is finally stored in the water production tank. The vacuum pump continuously maintains the vacuum state of the water production circuit on the permeation side of the pervaporation membrane assembly, provides a driving force for mass transfer, and promotes the pervaporation process.

[0047] Different from reverse osmosis technology, the influent of pervaporation desalination is less affected by salt concentration (osmotic pressure), which can even be ignored, and the pervaporation membrane has strong anti-pollution properties, so it can achieve a high recovery rate (no concentrated water or only a very small amount of concentrated water discharge). The main advantages of this design include: high energy utilization efficiency, reducing energy consumption through cascade utilization and recovery of heat; using pervaporation desalination technology, it can effectively remove salt and other pollutants in water; the system is compact in structure, and the components are closely connected, which improves the overall efficiency, and improves the utilization rate of water through the circulation design. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0049] Figure 1 is a flow chart of the present invention;

[0050] Figure 2 It is a structural schematic diagram of the present invention;

[0051] In the figure, 1. raw water buffer tank; 2. raw water circulation pump; 3. pre-condenser; 4. heating condensation coupler; 5. hot end heat exchanger; 6. pervaporation desalination membrane element; 7. cold end heat exchanger; 8. resin adsorption column; 9. produced water storage tank; 10. vacuum pump. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0053] Embodiment 1: As shown in the figure, a water purification process based on pervaporation desalination technology includes the following steps:

[0054] S1, water intake step: introducing raw water into the raw water buffer tank 1, and monitoring the water quality, temperature and liquid level of the raw water respectively by means of a conductivity sensor, a temperature sensor and a liquid level sensor arranged in the raw water buffer tank 1;

[0055] S2, raw water circulation step: pumping the raw water in the raw water buffer tank 1 through the raw water circulation pump 2, so that the raw water circulates in the system;

[0056] S4, heating step: transporting the raw water to the shell side of the precondenser 3, and then transporting the raw water passing through the shell side of the precondenser 3 to the hot end heat exchanger 5 of the heating condensation coupler 4 for heating;

[0057] S5, pervaporation step: the heated raw water is transported to the pervaporation desalination membrane element 6 for pervaporation treatment, and the concentrated water after treatment is refluxed to the raw water buffer tank 1 to form a cycle. At the same time, under the action of the vacuum pump 10, the water vapor that permeates the membrane enters the tube side of the precondenser 3 through the vacuum pipeline;

[0058] S6, condensation collection step: after the water vapor is pre-condensed in the tube of the pre-condenser 3, it enters the cold end heat exchanger 7 of the heating condensation coupler 4 for further condensation;

[0059] S7, produced water collection step: collect the condensed pure water into the produced water storage tank 9, and monitor the purity of the produced water by a conductivity sensor or a resistance sensor arranged in the produced water storage tank 9.

[0060] Embodiment 2: As shown in the figure, different from Embodiment 1, step S1 also includes the following pre-processing steps:

[0061] S11, water quality monitoring step of the raw water buffer tank 1: monitor the water quality of the raw water buffer tank 1 in real time through a conductivity sensor, and when the conductivity of the water in the buffer tank exceeds a preset range, discharge it through a first vent valve;

[0062] S12, water temperature adjustment step of the raw water buffer tank 1: monitor the water temperature of the raw water buffer tank 1 in real time through a temperature sensor, and when the water temperature is lower than a preset temperature, start the built-in heater for heating; when the water temperature is higher than the preset temperature, turn off the heater;

[0063] S13, raw water level control step: monitor the raw water level in real time through the level sensor, when the raw water level is lower than the minimum level, start water replenishment, when the raw water level reaches the maximum level, stop water intake.

[0064] Furthermore, step S4 also includes the following heating control step:

[0065] S41, monitoring the inlet temperature and outlet temperature of the hot end heat exchanger 5 of the heating condensation coupler 4;

[0066] S42. Adjust the heating power according to the outlet temperature. When the outlet temperature is lower than the set value, increase the heating power; when the outlet temperature is higher than the set value, reduce the heating power.

[0067] A closed-loop control system is established by real-time monitoring of temperature parameters at the inlet and outlet of the hot end heat exchanger 5 of the heating condensation coupler 4. When the system detects that the outlet temperature is lower than the preset value, the controller will automatically increase the heating power to ensure that the treated water temperature can reach the temperature required by the pervaporation process; conversely, when the outlet temperature exceeds the set value, the system will reduce the heating power accordingly to avoid excessive energy consumption and possible adverse effects caused by excessive water temperature.

[0068] This precise temperature control solution not only enables the system to always operate within the optimal temperature range, ensuring the treatment efficiency and water quality of the pervaporation process, but also can dynamically adjust energy input according to actual needs, significantly improving energy utilization efficiency and reducing operating costs.

[0069] Furthermore, step S5 also includes the following pervaporation process control steps:

[0070] S51, pervaporation desalination membrane element 6 pressure difference monitoring:

[0071] a. Install a vacuum pressure sensor on the permeate side of the pervaporation desalination membrane element 6 to monitor the permeate side pressure P in real time;

[0072] b. When the pressure difference P does not meet the preset range, an alarm will be sounded and corresponding adjustments will be made;

[0073] S52, permeation flux monitoring of pervaporation desalination membrane element 6:

[0074] a. Install a flow meter at the water production end of the pervaporation desalination membrane element 6 to measure the permeate water volume V per unit time;

[0075] b. Record the effective membrane area A of the pervaporation desalination membrane element 6;

[0076] c. Calculate the permeation flux per unit time and per unit area J = V / (A·t);

[0077] d. Establish the relationship curve between permeation flux J and operation time t;

[0078] e. When the permeate flux drops by more than 20%, the pervaporation desalination membrane element 6 is cleaned;

[0079] S53, Pervaporation Desalination Membrane Element 6 Separation Efficiency Analysis:

[0080] a. Install conductivity sensor EC1 at the water inlet end of the pervaporation desalination membrane element 6 to measure the inlet water conductivity;

[0081] b. Install conductivity sensor EC2 at the water production end of pervaporation desalination membrane element 6 to measure the conductivity of produced water;

[0082] c. Calculate the desalination rate R = (EC1-EC2) / EC1×100%;

[0083] d. When the desalination rate is lower than the set value, adjust the operating parameters or perform membrane element maintenance.

[0084] This step achieves precise management of the membrane separation process through three key dimensions. First, in terms of pressure difference monitoring, a vacuum pressure sensor is installed on the permeate side of the membrane element to monitor the permeate side pressure in real time. When the pressure difference deviates from the preset range, an alarm is issued and adjusted in time, ensuring the stable driving force required for the membrane separation process.

[0085] In terms of permeation flux monitoring, the system measures the amount of permeated water per unit time through a flow meter, calculates the unit permeation flux based on the effective area of ​​the membrane element, and establishes a flux-time relationship curve. When the permeation flux drops by more than 20%, the membrane element cleaning mechanism is automatically triggered to effectively prevent and control membrane pollution problems.

[0086] In terms of separation efficiency analysis, conductivity sensors are installed at the water inlet and water production ends respectively to calculate the desalination rate in real time. When the desalination rate is lower than the set value, the operating parameters are adjusted in time or the membrane elements are maintained to ensure the stability of the water production quality.

[0087] Embodiment 3: As shown in the figure, the difference from Embodiment 2 is that step S6 also includes the steps of temperature monitoring and recording.

[0088] Install temperature sensor T1 at the inlet of pre-condenser 3 tube pass to monitor the water vapor inlet temperature;

[0089] Install temperature sensor T2 at the outlet of pre-condenser 3 to monitor the outlet temperature of pre-condensed water;

[0090] Install temperature sensor T3 at the shell inlet of pre-condenser 3 to monitor the cooling water inlet temperature;

[0091] A temperature sensor T4 is installed at the outlet of the shell side of the pre-condenser 3 to monitor the cooling water outlet temperature.

[0092] The temperature monitoring system of the pre-condenser 3 adopts a complete four-point temperature monitoring solution, and realizes all-round monitoring of the heat exchange process by arranging temperature sensors at key positions. Specifically, the T1 sensor at the tube inlet can monitor the initial temperature of the water vapor entering the system, and the T2 sensor at the tube outlet monitors the temperature of the condensed water after pre-condensation. The temperature difference between these two measuring points directly reflects the effect of the condensation process; at the same time, the T3 sensor at the shell inlet and the T4 sensor at the outlet monitor the inlet and outlet temperatures of the cooling water respectively. This set of data can not only reflect the temperature rise of the cooling water, but also be used to calculate the heat exchange efficiency and heat recovery of the system.

[0093] The above temperature monitoring layout enables the operator to grasp the operating status of the pre-condenser 3 in real time, discover abnormal heat exchange efficiency in time, and optimize the operating parameters by analyzing the temperature data, and adjust the cooling water flow or other process parameters. In addition, the complete temperature data record also provides reliable data support for equipment fault diagnosis, system performance evaluation and energy efficiency analysis.

[0094] Furthermore, after step S7, a resin adsorption step S8 is also included: the condensed pure water portion is sent to a resin adsorption column 8, the resin is a polishing resin, and the resin adsorption column 8 is used to further remove ionic impurities in the water, thereby preparing ultrapure water, and the prepared ultrapure water is sent to another water production tank 9.

[0095] By configuring the polishing resin adsorption column 8 at the end of the system, the strong adsorption capacity of the ion exchange resin for residual ions in the water can be fully utilized to further remove the trace ion impurities that may remain in the water after the pervaporation treatment. The polishing resin has extremely high exchange capacity and selectivity, and can adsorb and remove both cations and anions in the water. This deep treatment enables the final water production to meet the ultrapure water standard.

[0096] Furthermore, the heating and condensing coupler 4 is in one of the following two forms: a heating and condensing device based on multiple semiconductor refrigeration plates connected in series or in parallel, wherein the hot end of the semiconductor refrigeration plate is used to heat the raw water and the cold end is used to condense the produced water; or a refrigeration compressor, wherein the condensing end is used to heat the raw water and the evaporating end is used to condense the produced water.

[0097] The heating and condensing device based on multiple semiconductor refrigeration chips connected in series or in parallel utilizes the thermoelectric effect of semiconductor refrigeration chips, which can directly convert electrical energy into thermal energy to achieve the heating of raw water and the condensation of produced water. The hot end of the semiconductor refrigeration chip can absorb electrical energy, generate heat, and heat the raw water, while its cold end can absorb heat and condense the produced water vapor. By connecting multiple semiconductor refrigeration chips in series or in parallel, the power of heating and condensation can be adjusted to meet different needs. This solution has the advantages of small size, light weight, easy installation and maintenance, and is particularly suitable for small water purification systems.

[0098] The solution using a refrigeration compressor utilizes the phase change process of the refrigerant to achieve heat transfer. The refrigeration compressor compresses the refrigerant to increase its temperature and pressure, and then releases heat in the condenser to heat the raw water. At the same time, the refrigerant absorbs heat in the evaporator and condenses the produced water vapor. This solution can provide greater cooling and heating power and is suitable for larger water purification systems.

[0099] The above two schemes are both effective heating condensing coupler 4 designs, which have the following advantages: directly using electric energy for heating and condensing, avoiding heat loss in traditional heat exchange methods and improving energy utilization efficiency; not using any chemicals, which is more environmentally friendly; the heating and condensing power can be conveniently controlled by adjusting the current or compressor speed.

[0100] Furthermore, the raw water buffer tank 1 and the produced water storage tank 9 are both thermal insulation type storage tanks, and the pipelines connecting the various components are made of thermal insulation materials or coated with thermal insulation layers.

[0101] The raw water buffer tank 1 and the produced water storage tank 9 are both designed with thermal insulation, which can effectively reduce heat loss to the outside, ensure the temperature stability of the raw water and produced water, and provide guarantee for the normal operation of the entire water purification system. Especially for preheated raw water and condensed produced water, insulation measures can effectively reduce heat loss, improve energy utilization efficiency, and save energy consumption.

[0102] The pipelines connecting the various components are made of insulation materials or covered with insulation layers, which can also effectively reduce heat loss and improve system efficiency. For example, in the process of the condenser transporting produced water to the produced water storage tank 9, the insulated pipelines can effectively reduce the heat loss of the produced water, improve the condensation efficiency and save energy.

[0103] The thermal insulation design can not only improve energy utilization efficiency, but also extend the service life of the equipment. Since the thermal insulation measures can effectively reduce heat loss and reduce temperature fluctuations, they can effectively reduce the thermal stress of internal parts of the equipment, slow down the aging of the equipment, and extend the service life of the equipment.

[0104] Furthermore, the pervaporation desalination membrane element 6 is a hydrophilic pervaporation desalination membrane or a reverse osmosis membrane with a desalination rate greater than 99.5%, and the membrane component is in the form of a spiral membrane or a hollow fiber column membrane.

[0105] In terms of membrane module configuration, both rolled membrane elements and hollow fiber membrane elements can provide a large specific surface area, thereby significantly improving the membrane separation efficiency per unit volume. Rolled membrane elements have the characteristics of compact structure and small footprint, while hollow fiber membrane elements have higher membrane area density and better self-support. In addition, another outstanding advantage of this membrane separation system is its near-zero emission environmental protection characteristics. During operation, there is no need to continuously discharge concentrated water, only a small amount of accumulated concentrated liquid needs to be discharged regularly, which greatly reduces the burden of wastewater treatment and improves the utilization efficiency of water resources.

[0106] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A water purification process based on pervaporation desalination technology, characterized in that: The following steps are involved: S1, water intake step: introducing raw water into a raw water buffer tank, and monitoring the water quality, temperature and liquid level of the raw water respectively through a conductivity sensor, a temperature sensor and a liquid level sensor arranged in the raw water buffer tank; S2, raw water circulation step: pumping out the raw water in the raw water buffer tank through the raw water circulation pump, so that the raw water circulates in the system; S4, heating step: transporting the raw water to the shell side of the pre-condenser, and then transporting the raw water passing through the shell side of the pre-condenser to the hot end heat exchanger of the heating condensation coupler for heating; S5, pervaporation step: the heated raw water is transported to the pervaporation desalination membrane element for pervaporation treatment, and the concentrated water after treatment is returned to the raw water buffer tank to form a cycle. At the same time, under the action of the vacuum pump, the water vapor that permeates the membrane enters the tube side of the pre-condenser through the vacuum pipeline; S6, condensation collection step: after the water vapor is pre-condensed in the tube of the pre-condenser, it enters the cold end heat exchanger of the heating condensation coupler for further condensation; S7, produced water collection step: collect the condensed pure water into a produced water storage tank, and monitor the purity of the produced water by a conductivity sensor or a resistance sensor arranged in the produced water storage tank.

2. A water purification process based on pervaporation desalination technology according to claim 1, characterized in that: Step S1 also includes the following preprocessing steps: S11, water quality monitoring step of the raw water buffer tank: monitor the water quality of the raw water buffer tank in real time through a conductivity sensor, and when the conductivity of the water in the buffer tank exceeds a preset range, discharge it through a first vent valve; S12, raw water buffer tank water temperature adjustment step: monitor the water temperature of the raw water buffer tank in real time through a temperature sensor, and when the water temperature is lower than a preset temperature, start the built-in heater for heating; when the water temperature is higher than the preset temperature, turn off the heater; S13, raw water level control step: monitor the raw water level in real time through the level sensor, when the raw water level is lower than the minimum level, start water replenishment, when the raw water level reaches the maximum level, stop water intake.

3. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: Step S4 also includes the following heating control steps: S41, monitoring the inlet temperature and outlet temperature of the heat exchanger at the hot end of the heating condensing coupler; S42. Adjust the heating power according to the outlet temperature. When the outlet temperature is lower than the set value, increase the heating power; when the outlet temperature is higher than the set value, reduce the heating power.

4. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: Step S5 also includes the following pervaporation process control steps: S51, pervaporation desalination membrane element pressure difference monitoring: a. Install a vacuum pressure sensor on the permeate side of the pervaporation desalination membrane element to monitor the permeate side pressure P in real time; b. When the pressure difference P does not meet the preset range, an alarm will be sounded and corresponding adjustments will be made; S52, permeation flux monitoring of pervaporation desalination membrane elements: a. Install a flow meter at the water production end of the pervaporation desalination membrane element to measure the permeate water volume V per unit time; b. Record the effective membrane area A of the pervaporation desalination membrane element; c. Calculate the permeation flux per unit time and per unit area J = V / (A·t); d. Establish the relationship curve between permeation flux J and operation time t; e. When the permeate flux drops by more than 20%, the pervaporation desalination membrane element is cleaned; S53, Analysis of separation efficiency of pervaporation desalination membrane elements: a. Install conductivity sensor EC1 at the water inlet of the pervaporation desalination membrane element to measure the conductivity of the inlet water; b. Install conductivity sensor EC2 at the water production end of the pervaporation desalination membrane element to measure the conductivity of the produced water; c. Calculate the desalination rate R = (EC1-EC2) / EC1×100%; d. When the desalination rate is lower than the set value, adjust the operating parameters or perform membrane element maintenance.

5. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: Step S6 also includes the steps of temperature monitoring and recording. Install temperature sensor T1 at the inlet of the pre-condenser tube to monitor the water vapor inlet temperature; Install temperature sensor T2 at the outlet of the pre-condenser tube to monitor the outlet temperature of the pre-condensed water; Install temperature sensor T3 at the shell inlet of the pre-condenser to monitor the cooling water inlet temperature; A temperature sensor T4 is installed at the shell outlet of the pre-condenser to monitor the cooling water outlet temperature.

6. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: After step S7, a resin adsorption step S8 is also included: the condensed pure water portion is sent to a resin adsorption column, the resin is a polishing resin, and the resin adsorption column is used to further remove ionic impurities in the water, thereby preparing ultrapure water, and the prepared ultrapure water is sent to another water production tank.

7. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: The heating and condensing coupler is in one of the following two forms: a heating and condensing device based on a plurality of semiconductor refrigeration plates connected in series or in parallel, wherein the hot end of the semiconductor refrigeration plate is used to heat the raw water and the cold end is used to condense the produced water; or a refrigeration compressor, wherein the condensing end is used to heat the raw water and the evaporating end is used to condense the produced water.

8. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: The raw water buffer tank and the produced water storage tank are both thermal insulation type storage tanks, and the pipelines connecting the various components are made of thermal insulation materials or coated with thermal insulation layers.

9. The water purification process based on pervaporation desalination technology according to claim 1, characterized in that: The pervaporation desalination membrane element is a hydrophilic pervaporation desalination membrane or a reverse osmosis membrane with a desalination rate greater than 99.5%, and the membrane component is in the form of a roll membrane or a hollow fiber column membrane.

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