KR101551450B1 - Vacuum membrane distillation system for monitoring and controlling membrane wetting index, and method for the same - Google Patents

Abstract

Provided are a vacuum membrane distillation system for monitoring and controlling membrane a wetting index and a method thereof. The vacuum membrane distillation system can restore performance of the system by continuously measuring a membrane wetting index, recognizing the level of membrane wetting of a hydrophobic membrane depending on the state of the membrane wetting index, and preventing the membrane wetting on the surface of the membrane at room temperature by dry air or maintaining the vacuum in an inflow side of a hydrophobic membrane module depending on the membrane wetting index. In addition, the present invention is capable of self-diagnosis and self-healing with respect to the membrane wetting by monitoring the membrane wetting index combined with the liquid entry pressure (LEP) of the hydrophobic membrane, quantity of processed water, and variation coefficients of the water quality in a nondestructive state where the hydrophobic membrane module is not dismantled, and by controlling the membrane wetting of the hydrophobic membrane based on a maximum drivable filtering time calculated by the membrane wetting index.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum film distillation system capable of monitoring and controlling a film wettability index,

The present invention relates to a vacuum film distillation system, and more particularly, to a vacuum film distillation system capable of monitoring and controlling a membrane wetting index of a hydrophobic membrane module in a vacuum membrane distillation system used in a seawater desalination process, It is about the method.

As a seawater desalination process, a membrane distillation (evaporation) method, an electrodialysis method, and a reverse osmosis (RO) method are generally used. Here, the reverse osmosis method, which is mainly used, is a process of obtaining fresh water by applying a pressure higher than osmotic pressure to the influent water by using a high-pressure pump after pre-treatment. Since the consumption power is large and a hydrophilic membrane is used, the membrane is easily contaminated by floating particles and organic substances .

The Membrane Distillation (MD) process is a technology that compensates for each disadvantage by combining seawater desalination technology using heat and seawater desalination technology using membrane. This membrane distillation process is a technology that combines thermal phase change and membrane technology, and is a process that uses vapor pressure due to temperature difference as a driving force mainly in a hydrophobic separation membrane.

This membrane distillation process is a process for obtaining fresh water by passing steam through a hydrophobic separation membrane using a difference in vapor pressure generated between hot seawater having a temperature of 60 to 80 ° C and room temperature as a driving force. At this time, However, since it is possible to operate without pretreatment, it is possible to reduce the site area and operate with lower energy than other conventional seawater desalination processes. In addition, since the hydrophobic separation membrane is used, there is an advantage that the membrane contamination phenomenon due to organic substances and suspended particles is less.

In particular, such a membrane distillation process has less energy used in operation and a salt removal rate close to 100% when alternative energy such as waste heat and solar heat is available, compared with the conventional pressurized separation membrane process. At this time, even if the high-concentration influent water enters the membrane distillation process, there is little change in the permeation flux and the salt removal efficiency. In addition, the membrane distillation process consumes less heat energy than the conventional multi-stage distillation process, and has a merit that the chemical reaction between the separation membrane and the process water is less.

In this film distillation step, although the heated inflow solution always comes in contact with the separation membrane, the shape of the fluid flow on the permeation side can be classified as follows according to the configuration on the permeation side.

Specifically, a direct contact membrane distillation (DCMD) method in which cooling water flows directly in contact with the separator, an air gap film in which an air gap exists between the separator and the cold plate, Vacuum Membrane Distillation (VMD), which is a method of obtaining treated water by applying a vacuum pressure to the permeate side, and a sweep (sweep) process between a separator and a cold plate (Sweep gas membrane distillation (SGMD)), which is a method in which a gas flows through the membrane, is used.

In the direct contact membrane distillation method (DCMD), steam generated as the heated feed solution passes through the inflow side passes through the hydrophobic separation membrane and moves to the permeation side. At this time, the permeate solution (Permeate Solution) Refers to a process that flows in contact with the separation membrane. In this direct contact membrane distillation method (DCMD), the vapor pressure difference caused by the temperature gradient of the influent solution and the permeate solution acts as the driving force.

Next, the air gap film distillation method (AGMD) is a process in which the permeation side is composed of an air gap and a cooling plate, and the steam generated from the heated inflow solution passes through the air gap on the permeation side and collides with the cooling plate to condense the vapor. At this time, the existence of the air gap can reduce the heat loss caused by the heat conduction through the separation membrane.

Next, the accompanying gas film distillation method (SGMD) is a process in which a cold inert gas flows through the permeate side, and the inert gas has a low temperature and serves as a gas accompanied by it. At this time, the steam generated from the heated inflow solution exits the module together with the accompanying gas at the permeate side, and the steam is condensed in a separate condenser. At this time, since the amount of condensed steam is not so large and the amount of the accompanying gas required is considerable, a relatively large condenser is required.

Next, the vacuum film distillation (VMD) process is a process in which a vacuum pump is used to create a pressure near the vacuum on the permeation side. In order to separate the vaporized molecules from the influent solution, Should be applied lower. Accordingly, the vacuum film distillation (VMD) can remove the partial pressure in the membrane pores by applying a pressure close to vacuum, and the effect of removing the molecular diffusion resistance can be obtained.

In this membrane distillation process, ultrapure water can only be obtained by selectively passing steam only in the state where the raw water to be treated such as seawater is in direct contact with the fresh water. However, if the pressure exceeding the Liquid Entry Pressure (LEP) The seawater containing, for example, saline is permeated into the pores of the separation membrane, resulting in serious deterioration of the treated water quality. Accordingly, in the separation membrane in which the membrane wetting phenomenon occurs due to the pressure exceeding the liquid permeation pressure (LEP), water is caught in the gap and the separation membrane is required to be dried for 24 hours or more at room temperature . Here, the liquid permeation pressure (LEP) is determined by the contact angle of the film, the surface tension, the pore size and the like, and this has been confirmed through a number of studies.

In particular, when a vacuum pressure is applied to the permeation side to increase the permeation flux as in the vacuum film distillation (VMD) method, a high permeation flux can be obtained compared to the DCMD technique described above, Lt; / RTI > That is, the vacuum film distillation method (VMD) uses the vapor pressure due to the temperature difference as the driving pressure and applies the hydrophobic separation membrane and the vacuum pump. Therefore, when the hydrophobic separation membrane is operated for a long time or exposed to various pollutants, Membrane wetting phenomenon occurs and the permeation does not progress any more.

The hydrophobic separation membrane, which has membrane wetting phenomenon due to the pressure exceeding the liquid permeation pressure (LEP), is filled with water and the membrane can be recovered in its performance. At this time, the liquid permeation pressure (LEP) which can be used as an index of the wetting phenomenon in the hydrophobic separation membrane means a minimum pressure at which the solution can enter into the membrane pore.

Therefore, when hydrostatic pressure exceeding the liquid permeation pressure (LEP) is applied, separation membrane wetting phenomenon may occur, which may act as a cause of reducing the quality of the treated water. In addition, at the time when the membrane wetting phenomenon actually occurs, the hydrophobic separation membrane is hydrophilized, the permeation flux rapidly increases, and the concentration of TDS (Total Dissolved Solid), which is the concentration of dissolved solids in the treated water, is increased .

), 황산이온(

), 탄산이온(

) 등에 의해 생성되는 스케일 물질 등의 무기염 결합 상태 및 농도 등 막 오염 유발물질의 영향을 받아서 막 젖음 현상이 가속화될 수 있다.This membrane wetting phenomenon can be accelerated depending on the kind of contaminants in the raw water to be treated. In particular, when a membrane distillation technique is applied to treat groundwater, seawater, nose water and the like, for example, Characteristic and concentration, calcium ion (

), Sulfate ion (

), Carbonate ions (

) Due to the influence of the film-contamination-inducing substance such as the inorganic salt-binding state and the concentration of the scale substance, etc.

In addition, in applying the membrane distillation process to treat the concentrated water of the reverse osmosis membrane for desalination of seawater, calcium ions, sulfate ions and bicarbonate ions exist in the concentration of the calcium sulfate and calcium carbonate in the seawater concentrated water, Calcium sulphate and calcium carbonate crystals interfere with the pore gap in the hydrophobic membrane of the membrane distillation system, which is the main cause of membrane contamination.

Therefore, in the water treatment system using the membrane distillation technology, the membrane wetting index through the membrane permeation index (LEP) of the hydrophobic membrane, the treated water quantity and the water quality is monitored and the membrane wettability index Accordingly, there is a need for a control technique for maintaining a vacuum on the inlet side or for quickly preventing film wetting on the surface of the separation membrane at room temperature by dry air.

Particularly, in the case of the hydrophobic separation membrane applied to the membrane distillation technique, the membrane is a flat membrane or a hollow fiber membrane, and when the membrane wetting phenomenon actually starts, the influent water is rapidly transferred to the permeation side to change the water quality on the permeation side, It takes a long time to recover. This leads to a problem that the recovery rate of the membrane distillation system is lowered, and when the high temperature steam is used to control the membrane wetting, material denaturation occurs. Therefore, the membrane wettability index is actually monitored on the scale of the hydrophobic membrane module, A rapid membrane wetting prevention and control technology is required.

Korean Patent No. 10-956765 filed on January 18, 2008, entitled "Membrane Module for Membrane Distillation and High-Efficiency Membrane Distillation Separation Process Using the Same" Korean Patent No. 10-1020316 filed on Apr. 28, 2010, entitled " Ozone Desalination System Using Membrane Distillation Method " Korean Patent No. 10-1298724 filed on Aug. 12, 2011, entitled "A membrane-distillation type osmosis desalination apparatus in which a part of the induction solution is directly re-supplied to the osmosis separator" Korean Patent No. 10-1426000 filed on Dec. 6, 2012, entitled "PTFE Hollow Membrane Distillation Membrane and Method of Manufacturing the Same"

In order to solve the problems described above, the present invention provides a method for continuously measuring the membrane wetting index in a vacuum membrane distillation system and determining the degree of membrane wetting of the hydrophobic separator according to the state of the membrane wettability index Which can restore the performance of the vacuum membrane distillation system by keeping the vacuum at the inlet side of the hydrophobic membrane module according to the membrane wettability index or by quickly preventing membrane wetting at the membrane surface at room temperature by dry air, And to provide a vacuum film distillation system and method therefor.

Another problem to be solved by the present invention is to provide a membrane that combines the liquid permeation pressure (LEP) of the hydrophobic membrane with the coefficient of variation of the water quality and the water quality in the non-destructive state where the hydrophobic membrane module is not disassembled with respect to the membrane of the actual hydrophobic membrane module. It is possible to monitor and control the membrane wetting index, which can self-diagnose and self-heal the membrane wetting by controlling the wetting of the hydrophobic membrane based on the maximum operable filtration time calculated by the membrane wettability index A vacuum film distillation system and a method thereof.

As a means for achieving the above technical object, a vacuum film distillation system capable of monitoring and controlling the film wettability index according to the present invention is characterized in that a hydrophobic separation membrane of a vacuum film distillation system applied to a water treatment apparatus is used for a long time, A vacuum film distillation system for controlling film wettability caused by exposure of a trigger material, comprising: a hydrophobic separation membrane module, an influent storage tank, a steam generator, a TDS measuring device, a flow meter, a drying air supply unit, A vacuum film distillation system installed to generate steam by passing steam through a difference in vapor pressure generated between inflow water at normal temperature as a driving force; And a membrane wetting index of the hydrophobic separation membrane module to monitor the membrane wettability index, measure the water quality change and the permeation flux of the treated water, and measure the measured membrane wettability or the measured permeate flux and water quality And a membrane wetting index monitoring and control unit for controlling the hydrophobic membrane module to control the supply of vacuum pressure and dry air to the hydrophobic membrane module, The membrane is wetted on the surface of the hydrophobic separation membrane by controlling the vacuum to be maintained on the inlet side of the hydrophobic separation membrane module according to the membrane wettability index or to be supplied with dry air.

The vacuum membrane distillation system includes a hydrophobic separation membrane module installed to generate steam by passing steam through a difference in vapor pressure generated between seawater and an influent of normal temperature, An inflow water reservoir for supplying inflow water by an inflow pump; A steam generator installed on an inflow side of the hydrophobic separation membrane module to supply steam to the inflow water; A TDS measuring device installed on the permeate side of the hydrophobic separation membrane module for measuring total dissolved solids; A flow meter installed on the permeate side of the hydrophobic separation membrane module and measuring the flow rate of the treated water; A dry air supply unit for supplying dry air to the surface or inside of the hydrophobic separation membrane under the control of the vacuum pump and the dry air valve control unit; And a treated water storage tank for storing and discharging the treated water that has passed through the hydrophobic separation membrane module.

Here, the membrane wettling index monitoring and control unit may include a membrane wettability measuring unit installed on the inlet side of the hydrophobic membrane module to measure the membrane wettability index to monitor the membrane wettability index of the hydrophobic membrane; A permeate flow rate and water quality change measuring unit for measuring a change in water quality according to a flow rate of the treated water measured by the flow meter and measuring a permeate flow rate according to the TDS measured by the TDS meter; A film wettability determining unit for determining a film wettability of the hydrophobic separation membrane in accordance with the membrane wettability measured by the membrane wettability measurement unit and / or the permeation flux and the water quality measured by the permeation flux and water quality measurement unit; And a vacuum pump and a dry air valve controller for controlling the vacuum pump to operate so as to apply a vacuum pressure to the hydrophobic separation membrane module and for controlling the drying air supply unit to spray dry air to the hydrophobic separation membrane module can do.

)으로 주어지고,

, 여기서,

는 분리막의 형상계수를 나타내고,

는 액체의 표면장력을 나타내며,

는 분리막과 액체 사이의 접촉각을 나타내고,

는 최대 공극의 크기를 나타내는 것을 특징으로 한다.Herein, the membrane wettling index monitoring and control unit selects and monitors the pressure point at which the membrane wetting of the hydrophobic separation membrane is accelerated at the beginning of the operation of the hydrophobic separation membrane module, and determines the pressure at which the measured membrane wetting is generated as the membrane wettability index , The film wettability index is expressed by the liquid permeation pressure (

), ≪ / RTI >

, here,

Represents the shape coefficient of the separation membrane,

Represents the surface tension of the liquid,

Represents the contact angle between the separation membrane and the liquid,

Is characterized by indicating the size of the maximum air gap.

The membrane wettance monitoring and control unit calculates the temperature polarization and concentration polarization of the hydrophobic separation membrane relative to the target influent water (raw water), predicts the permeation flux considering the temperature and concentration on the surface of the separation membrane, % After the predetermined time has elapsed.

Herein, the membrane wetting index monitoring and control unit is characterized in that the pressure is gradually increased from the inside to the outside of the hydrophobic separation membrane module, and the pressure time point at which the pressure change is greatest at the pressurized pressure is selected as the point at which the membrane wetting is accelerated do.

In this case, one side of the permeate side pipe of the hydrophobic separation membrane module is installed as a transparent tube, and the pressure is increased step by step so that the bubble, which is a time point at which the air velocity rapidly accelerates from incomplete pores due to membrane wetting phenomenon of the hydrophobic separation membrane, And the time point at which the bubbles are generated is selected as the point at which the film wetting is accelerated.

As another means for achieving the above technical object, a vacuum film distillation method capable of monitoring and controlling the film wettability index according to the present invention is characterized in that a hydrophobic separation membrane of a vacuum film distillation system applied to a water treatment apparatus is used for a long time Or membrane fouling caused by the exposure of a membrane fouling material, the method comprising the steps of: a) measuring the membrane wettability index at the membrane surface of the hydrophobic membrane module with the membrane wettability index measurement; b) filling the inlet side piping of the hydrophobic separation membrane module with a wetting index indicator; c) gradually turning off the first on / off motor-operated valve installed on the inflow side pipe of the hydrophobic separation membrane module and gradually pushing the inflow pump for supplying inflow water to the inflow side pipe; d) monitoring a pressure of the inflow pump at a time when bubbles are generated by observing a transparent tube installed in the permeate side pipe of the hydrophobic separation membrane module; e) judging whether the film wettability is judged by judging the film wettability of the separation membrane of the hydrophobic separation membrane module; f) If it is determined that the membrane wetting phenomenon has occurred in the separation membrane of the hydrophobic separation membrane module, the first and second on / off electric valves before and after the hydrophobic separation membrane module are turned off and the vacuum pump and the dry air valve control unit Operating the pump to keep the inlet side of the hydrophobic membrane module in vacuum; g) operating the dry air supply unit under the control of the vacuum pump and the dry air valve control unit to dehumidify the surface and inside of the hydrophobic separation membrane by injecting dry air into the inlet side of the hydrophobic separation membrane module; And h) re-measuring the film wettability index in the membrane wettability measuring unit and checking whether the membrane wettability is judged by restoring the number of membrane wettability.

In the step (a), the temperature polarization and the concentration polarization of the hydrophobic separator for the target influent water (raw water) are calculated to predict the permeation flux considering the temperature and the concentration at the surface of the separator, The film wettability index is calculated after a predetermined time.

Here, the calculated film wettability index is stored in a database to monitor the trend of the film wettability index during the long-term operation, and the film wetting can be prevented in advance by circulating and supplying the dry air repeatedly according to the tendency of the film wettability index .

In step c), the inflow water stored in the inflow water reservoir is gradually pressurized in steps of 3 bar or less, and the pressure change at the pressurized pressure is the largest. The time point at which the film wetting is accelerated is selected.

Here, in step d), a pressure condition in which a pressure higher than the liquid permeation pressure (LEP) is applied to the hydrophobic separation membrane in accordance with the pressure of the inflow pump, thereby accelerating the wetting of the membrane, is confirmed, and when the membrane wetting of the initial hydrophobic separation membrane is accelerated The pressurization with a pressure corresponding to 80% of the pressure condition of the membrane can be judged early.

In the step d), a transparent tube is installed on one side of the permeate side pipe of the hydrophobic separation membrane module, and the pressure is increased step by step, so that the bubble, which is the time point at which the air flow rate rapidly accelerates from incomplete pores due to film wettability of the hydrophobic separation membrane And the time point at which the film wetting is accelerated is selected as the time point at which the film wetting is accelerated.

In the case where seawater is used as the wetting index indicator in step b), it is necessary to determine the time point at which the TDS change occurs by measuring the permeate side salt concentration with the TDS measuring instrument in step d), or, When the chromogenic material is used, the UV absorbance of the permeation side salt concentration is measured in the step d), and the time point at which the absorbance value changes is confirmed.

In step e), the controller determines whether the initial wetness number is changed by 50% or whether the measured wetness number is smaller than the predetermined wetting index.

Here, in step h), it is possible to determine whether the film wettability is restored to 80% or more of the initial wetness index or recovered to a set value or more.

According to the present invention, in the vacuum film distillation system, the membrane wetting index is continuously measured, the degree of film wettability of the hydrophobic separator is determined according to the state of the film wettability index, The performance of the vacuum film distillation system can be restored by keeping the vacuum on the inlet side or by quickly preventing the membrane wetting on the surface of the separator at room temperature by dry air.

According to the present invention, the membrane wettability index obtained by combining the liquid permeation pressure (LEP) of the hydrophobic separator, the treated water quantity and the water quality coefficient is monitored in the non-destructive state where the hydrophobic membrane module is not disassembled with respect to the membrane of the actual hydrophobic membrane module , It is possible to self-diagnose and self-heal the membrane wetting by controlling the membrane wetting of the hydrophobic separation membrane based on the maximum operable filtration time calculated by the membrane wettability index, thereby improving the recovery rate during the operating period of the vacuum membrane distillation system And it is possible to provide driving convenience.

1 is a configuration diagram of a vacuum film distillation system according to an embodiment of the present invention.
2 is a schematic view for explaining a vacuum film distillation system capable of monitoring and controlling the film wettability index according to an embodiment of the present invention.
3 is a specific configuration diagram of a vacuum film distillation system capable of monitoring and controlling the film wettability index according to an embodiment of the present invention.
4A and 4B are operational flowcharts of a method of monitoring and controlling the film wettability index of a vacuum film distillation system according to an embodiment of the present invention.
5 is a view illustrating an operation result of a vacuum film distillation system capable of monitoring and controlling a film wettability index according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the term "part" or the like, as described in the specification, means a unit for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

[Vacuum membrane distillation system capable of monitoring and controlling membrane wetting index]

1 is a configuration diagram of a vacuum film distillation system according to an embodiment of the present invention.

1, a vacuum film distillation system 100 according to an embodiment of the present invention includes a steam generating unit 111, a first thermometer 112, an inflow water reservoir 113, an inflow pump 114, Off valve 115, a dry air supply section 116, a hydrophobic separation membrane module 117, a flow meter 118, a second on / off electromotive valve 119, a heat exchanger 120, a cooling water reservoir 121, A second thermometer 122, a TDS measuring device 123, a pressure gauge 124, a process water reservoir 125, a third on / off electric motor 126, a vacuum pump 127, a fourth on / Off valve 132, a de-wetting reservoir 129, a fifth on / off electromotive valve 130 and a sixth on / off electromotive valve 131.

The steam generating unit 111 generates steam so that the steam passes through the hydrophobic separator module 117 with a difference in vapor pressure generated between the hot seawater at 60 to 80 ° C and the inflow water at room temperature. The first thermometer 112 is connected to the steam generator 111 and the hydrophobic separator module 100 to check whether the steam of the steam generator 111 is at a predetermined temperature, 117 on the inlet piping.

The inflow pump 114 supplies the inflow water stored in the inflow water reservoir 113 onto the inflow pipe between the steam generation unit 111 and the hydrophobic separation membrane module 117.

The first on / off electromotive valve 115 is installed on the upstream side of the hydrophobic separation membrane module 117 and opens and closes the inflow water flow. The second on / off electromotive valve 119 is connected to the hydrophobic separation membrane module 117, To open and close the process water flow.

The dry air supply unit 116 is installed on the inflow pipe between the first on-off electromotive valve 115 and the hydrophobic separation membrane module 117 so that the membrane surface of the hydrophobic separation membrane module 117 and / And the dry air is sprayed into the inside.

The hydrophobic membrane module 117 includes a membrane in the form of a hollow fiber membrane or a flat plate membrane and is installed to generate fresh water through the steam with a difference in the vapor pressure generated between the seawater and the influent water at room temperature as a driving force. (118) is installed on the permeate side of the hydrophobic separation membrane module (117) to measure the flow rate of the treated water.

The heat exchanger 120 is installed on the permeate side of the hydrophobic separation membrane module 117, and the temperature of the treated water is lowered to room temperature by the cooling water supplied from the cooling water storage tank 121. At this time, the second thermometer 122 is installed to measure the temperature of the cooling water supplied from the cooling water storage tank 121.

The TDS measuring device 123 measures the concentration (TDS) of the dissolved solids of the treated water which has been warmed to room temperature through the heat exchanger 120, and the pressure gauge 124 is disposed on the permeate side of the hydrophobic separation membrane module 117, Is installed on the permeation side of the hydrophobic separation membrane module 117 to measure the pressure.

The process water reservoir 125 is installed on the permeate side of the hydrophobic separation membrane module 117 to store treated water and a third on / off electric motor valve 126 is installed at the rear end of the treated water reservoir 125, The water flow is opened and closed.

The vacuum pump 127 is installed on the permeate side of the hydrophobic separation membrane module 117 to keep the hydrophobic separation membrane module 117 in a vacuum.

A de-wetting reservoir 129 is provided on the permeate side of the hydrophobic separator module 117 and a fourth on / off electromotive valve 128 and a second on / off valve 128 are provided on the front and rear ends of the non- A fifth on / off motor-operated valve 130 may be provided and a sixth on / off motor-operated valve 131 may be installed between the non-wetted water storage tank 129 and the influent water storage tank 113.

FIG. 2 is a schematic view for explaining a vacuum film distillation system capable of monitoring and controlling the film wettability index according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between the film wettability index FIG. 2 is a specific configuration diagram of a vacuum film distillation system that can be used.

1 to 3, a vacuum film distillation system capable of monitoring and controlling the film wettability index according to an embodiment of the present invention is a system in which a hydrophobic separation membrane of a vacuum film distillation system applied to a water treatment apparatus is used for a long period of time, A vacuum film distillation system for controlling the film wettability phenomenon caused by exposure of a pollution inducing substance, comprises a vacuum film distillation system 100 shown in FIG. 1 and a film wettance index monitoring and control unit 200 shown in FIG. 3, . The film wetting index monitoring and control unit 200 includes a film wetting index measuring unit 210, a film wettability determination unit 220, a permeation flow rate and water quality change measuring unit 230, 240, a vacuum pressure and dry air injection time determination unit 250, and a vacuum pump and dry air valve control unit 260.

The vacuum film distillation system 100 is for obtaining treated water by applying a vacuum pressure to the permeate side of the hydrophobic separation membrane module 117. The film wetting phenomenon of the hydrophobic separation membrane is intermittently injected and injected according to the film wettability index A self-healing membrane wetting index monitoring and control unit 200 can be incorporated, as described above with reference to FIG.

The membrane wetting rate monitoring and control unit 200 measures the membrane wetting index by measuring the membrane wetting index of the hydrophobic separation membrane module 117 and measures the water quality change and the permeation flux of the treated water, The membrane wetting degree of the hydrophobic separation membrane is determined according to the measured membrane wettability or the measured permeation flux and the water quality change, and the vacuum pressure and dry air are supplied to the hydrophobic separation membrane module 117. The membrane wettability monitoring and control unit 200 may control the membrane wetting factor on the surface of the hydrophobic separator membrane 117 so that the vacuum is maintained or the dry air is supplied on the inlet side of the hydrophobic separator module 117 according to the membrane wettability index, .

1 to 3, the hydrophobic separation membrane module 117 of the vacuum membrane distillation system 100 includes a hollow fiber membrane or a separator in the form of a flat membrane. The hydrophobic separation membrane module 117 has a vapor pressure Is used as a driving force to transmit steam to generate fresh water.

As shown in FIGS. 2 and 3, the membrane wettability measuring unit 210 of the membrane wettling index monitoring and control unit 200 measures the film wettability index of the membrane of the hydrophobic separation membrane module 117, Measure the wetting index.

The TDS measuring device 123 is installed on the permeate side of the hydrophobic separation membrane module 117 to measure the total dissolved solids TDS and the flow meter 118 is provided on the permeate side of the hydrophobic separation membrane module 117, Measure the flow rate.

As shown in FIG. 3, the permeation flow rate and water quality change measuring unit 230 measures the water quality change according to the flow rate of the treated water measured by the flow meter 118, and furthermore, by the TDS measuring device 123 The permeate flux is measured according to the measured TDS.

3, the film wettability determination unit 220 determines the film wettability based on the film wettance measured by the film wettability measurement unit 210 and / or the film wettability measured by the permeation flux and water quality measurement unit 230 The membrane wetting degree of the hydrophobic separation membrane is determined according to the permeation flux and the water quality change.

3, the operation continuity determination unit 240 determines whether the operation of the hydrophobic separation membrane module 117 is continued according to the degree of film wettability determined by the film wettability determination unit 220 . For example, if the degree of membrane wetting is judged to be a membrane wetting, the operation is stopped.

As shown in FIG. 3, the vacuum pressure and dry air injection time determination unit 250 determines that the film wettability is generated according to the film wettability determined by the film wettability determination unit 220, 117 are stopped, the vacuum pressure and the injection time of the dry air are determined so as to dry the surface and inside of the separation membrane of the hydrophobic separation membrane module 117.

2 and 3, the vacuum pump and dry air valve control unit 260 operates the vacuum pump 127 during the injection time determined by the vacuum pressure and dry air injection time determination unit 250, Controls the hydrophobic separation membrane module 117 to apply vacuum pressure and controls the drying air supply section 116 to operate to spray and supply dry air to the hydrophobic separation membrane module 117.

The dry air supply unit 116 supplies dry air to the inflow side of the hydrophobic separation membrane module 117 under the control of the vacuum pump and the dry air valve control unit 260, as shown in FIG.

As shown in FIGS. 1 and 2, the treated water storage tank 125 stores and discharges the treated water that has passed through the hydrophobic separation membrane module 117.

1 to 3, in order to monitor and measure the film wettability index on the scale of the actual hydrophobic separation membrane module 117 according to the present invention, the operation of the hydrophobic separation membrane module 117 is temporarily stopped. At this time, Or the waste water heated by the steam generating unit 111 and the cooling water on the permeate side of the hydrophobic separation membrane module 117 are temporarily transferred to the hydrophobic separation membrane module 117 without being transferred to the hydrophobic separation membrane module 117, Off motor valve 115 and the second on / off motor-operated valve 119 are closed. In addition, the pressure is gradually increased from the inside to the outside of the hydrophobic separation membrane module 117, and the pressure time point at which the pressure change is greatest at the pressurized pressure is selected as the point at which the membrane wetting is accelerated.

Alternatively, one side of the permeation side pipe of the hydrophobic separation membrane module 117 is installed as a transparent tube, and the pressure is increased step by step to generate a bubble which is a time point at which the air flow rate rapidly accelerates from incomplete pores due to membrane wetting phenomenon of the hydrophobic separation membrane And the time of occurrence of such a bubble may be selected as a point at which the wetting is accelerated.

As described above, the pressure time point at which the film wetting of the hydrophobic separation membrane at the initial stage of operation is accelerated is selected and monitored. At this time, it is possible to promptly determine whether or not the membrane wetting occurs by pressing the membrane at a pressure corresponding to 80% of the pressure condition in which the membrane wetting is accelerated.

)으로 주어진다. 이러한 막 젖음 현상은 소수성 분리막 모듈(117)의 분리막 표면에서 액체투과압력(

)의 감소로 나타나고, 액체투과압력(LEP)의 감소는 소수성 분리막 모듈(117)의 분리막 최대 기공 크기를 증가시키며, 또한, 상기 소수성 분리막 모듈(117)의 분리막과 처리될 용액과의 접촉각의 감소에 의해 발생한다.The pressure at which the membrane wetting is measured is referred to as a membrane wettability index, and the membrane wettability index is expressed by the following equation (1)

). This membrane wetting phenomenon is caused by the liquid permeation pressure (< RTI ID = 0.0 >

And the reduction of the liquid permeation pressure LEP increases the maximum membrane pore size of the hydrophobic membrane module 117 and decreases the contact angle between the membrane of the hydrophobic membrane module 117 and the solution to be treated Lt; / RTI >

는 분리막의 형상계수를 나타내고,

는 액체의 표면장력을 나타내며,

는 분리막과 액체 사이의 접촉각을 나타내고,

는 최대 공극의 크기를 나타낸다. 이때, 소수성 분리막 모듈(117)의 분리막의 소수성도가 높을수록 LEP가 커지고 최대 공극크기가 클수록 LEP는 작아지는 것을 알 수 있다. 이러한 LEP 측정은 소수성 분리막 모듈(117)의 분리막 비건조(Dewettting) 여부를 쉽게 알 수 있고, 이를 통해서 소수성 분리막 모듈(117)의 분리막의 거동을 대략적으로 예측할 수 있다.here,

Represents the shape coefficient of the separation membrane,

Represents the surface tension of the liquid,

Represents the contact angle between the separation membrane and the liquid,

Represents the maximum pore size. At this time, it can be seen that as the hydrophobicity of the separation membrane of the hydrophobic separation membrane module 117 increases, the LEP increases, and as the maximum pore size increases, the LEP decreases. The LEP measurement can easily determine whether or not the hydrophobic membrane module 117 is dewettable, and the behavior of the membrane of the hydrophobic membrane module 117 can be roughly predicted.

1 and 3, the flowmeter 118 and the TDS measuring device 123 provided on one side of the permeate side pipe of the hydrophobic membrane module 117 in operation are continuously monitored in addition to the membrane wettability index described above , And when the initially measured data changes by more than 20%, it can be diagnosed as the point at which the film wetting phenomenon accelerates.

Therefore, a method of monitoring the membrane wetting index by the pressurized pressure measuring method and monitoring the change of the flow rate and the water quality of the permeate-side treated water of the hydrophobic membrane module 117 are performed, and if any one of the two methods is met It is judged to be the time when membrane wetting occurs.

The vacuum film distillation system capable of monitoring and controlling the film wettability index according to the embodiment of the present invention is a vacuum film distillation system in which the hydrophobic membrane module (117) is circulated or stopped to prevent wetting of the hydrophobic membrane module (117) The drying air supply unit 116 injects the dry air into the hydrophobic separation membrane module 117 for 10 minutes or more under the condition that no fluid is contained in the separation membrane tank 117, By circulating the hydrophobic membrane module 117 for the operation time, the membrane wetting of the hydrophobic membrane membrane can be controlled by drying the hydrophobic membrane module 117.

Meanwhile, in the vacuum film distillation system capable of monitoring and controlling the film wettability index according to the embodiment of the present invention, the film wettance index monitoring point and the control period are controlled by a control signal for the target influent (raw water) By calculating the temperature polarization and concentration polarization of the hydrophobic separation membrane according to the following expressions (2) to (6), it is possible to estimate the permeation flux considering the temperature and concentration on the surface of the actual hydrophobic separation membrane, The film wettability index is calculated and the calculated film wettability index is stored in a database (not shown) to monitor the tendency of the film wettability index during a long-term operation. Thereafter, by supplying or circulating dry air repeatedly, It can be prevented in advance.

)를 계산하기 위해서는 수학식 2에서와 같이 분리막 표면에서의 증기압력(

)를 계산해야 하는데, 이러한 증기압력(

)은 수학식 4를 이용하여 소수성 분리막 모듈(117)의 분리막 표면에서의 온도(

)와 농도(

)를 이용하여 계산한다. 이때, 소수성 분리막 모듈(117)의 분리막 표면에서의 온도(

)와 농도(

)는 직접적으로 측정하는 것이 불가능하기 때문에 내부 최적화 알고리즘을 수렴하는 수치해석 알고리즘을 포함된 모델에 의하여 수학식 5 및 수학식 6을 이용하여 산출한다.Specifically, the permeation flux (

), The steam pressure at the surface of the membrane as shown in Equation (2)

). This vapor pressure (

) Is calculated from the temperature at the separation membrane surface of the hydrophobic separation membrane module 117 (

) And concentration (

). At this time, the temperature at the surface of the separation membrane of the hydrophobic separation membrane module 117

) And concentration (

) Can not be measured directly. Therefore, a numerical analysis algorithm for converging the internal optimization algorithm is calculated by using a model including Equation 5 and Equation 6.

)는 다음의 수학식 2와 같이 주어진다.First, the permeate flux (

) Is given by the following equation (2).

은 투과 플럭스(단위:

)를 나타내고,

는 진공 막증류 계수(단위: s/m)를 나타내며,

는 분리막 표면에서의 증기압력(단위: Pa)을 나타내고,

는 적용된 진공 압력(단위: Pa)을 나타낸다. 본 발명의 실시예에 따른 진공 막증류 시스템에서 소수성 분리막 표면의 투과 플럭스(

)가 15% 감소되는 시점에서 막 젖음지수를 측정한다.here,

The permeation flux (unit:

),

Represents the vacuum film distillation coefficient (unit: s / m)

Represents the vapor pressure (unit: Pa) at the separation membrane surface,

Represents the applied vacuum pressure (unit: Pa). In the vacuum film distillation system according to the embodiment of the present invention, the permeation flux of the surface of the hydrophobic separation membrane (

) Is decreased by 15%, the film wettability index is measured.

)는 다음의 수학식 3과 같이 주어진다.Further, in the above-described formula (2), the vacuum film distillation coefficient

) Is given by the following equation (3).

는 기공 크기(단위: ㎛)를 나타내고,

는 공극률(단위: 무차원)을 나타내며,

는 분리막 두께(단위: ㎛)를 나타내고,

는 분리막 굴곡비(단위: 무차원)를 나타내며,

은 물의 분자량(단위: g/mol)을 나타내고,

은 이상기체상수(단위: J/molㅇ K)를 나타내며,

은 분리막 표면에서의 유입 용액의 온도(단위: K)를 나타낸다.here,

Represents the pore size (unit: 占 퐉)

Represents the porosity (unit: dimensionless)

Represents the separation membrane thickness (unit: 占 퐉)

Represents the separation membrane bending ratio (unit: dimensionless)

Represents the molecular weight (unit: g / mol) of water,

Represents the ideal gas constant (unit: J / mol K)

Represents the temperature (unit: K) of the incoming solution at the separation membrane surface.

)은 다음의 수학식 4와 같이 주어진다.Further, in the above-mentioned equation (2), the steam pressure at the surface of the separation membrane

) Is given by the following equation (4).

는 증기압력(단위: atm)을 나타내고,

은 분리막 표면에서 유입 용액의 온도(단위: K)를 나타내며,

은 분리막 표면에서 유입 용액의 농도(단위: g/kg)를 나타낸다.here,

Represents the steam pressure (unit: atm)

Represents the temperature (unit: K) of the influent solution at the separation membrane surface,

Represents the concentration (unit: g / kg) of the influent solution at the separation membrane surface.

)는 다음의 수학식 5와 같이 주어진다.Further, in the above-mentioned equation (4), the concentration of the influent solution at the surface of the separation membrane

) Is given by the following equation (5).

은 유입 용액의 분리막 표면에서의 농도(단위: g/kg)를 나타내고,

는 유입 용액의 농도(단위: g/kg)를 나타내며,

은 플럭스(단위: kg/㎡ㅇs)를 나타내며,

는 물질전달 계수(단위: m/s)를 나타낸다.here,

Represents the concentration (unit: g / kg) of the incoming solution on the surface of the separation membrane,

Represents the concentration (unit: g / kg) of the influent solution,

Represents the flux (unit: kg / m < 2 > s)

Represents the mass transfer coefficient (unit: m / s).

)는 다음의 수학식 6과 같이 주어진다.Further, in the above-mentioned formula (4), the temperature at the surface of the separation membrane of the inflow solution

) Is given by the following equation (6).

는 열전달 계수(단위:

)를 나타내고,

는 유입 용액의 농도(단위: K)를 나타내며,

은 유입 용액의 분리막 표면에서의 온도(단위: K)를 나타내고,

은 플럭스(단위:

)를 나타내고,

는 증기의 잠열(단위: J/kg)을 나타낸다.here,

Is the heat transfer coefficient (unit:

),

Represents the concentration (unit: K) of the influent solution,

Represents the temperature (unit: K) at the separation membrane surface of the influent solution,

Is the flux (unit:

),

Indicates the latent heat of steam (unit: J / kg).

Therefore, according to the embodiment of the present invention, in the non-destructive state in which the hydrophobic separation membrane module is not disassembled, the liquid permeation pressure (LEP) of the hydrophobic separation membrane and the coefficient of variation of water quality The wetting index can be monitored and the membrane wetting of the hydrophobic membrane can be controlled based on the maximum operable filtration time calculated by the membrane wettability index. According to the embodiment of the present invention, the hydrophilicity between the separation membrane surface and the pores of the hydrophobic separation membrane module is rapidly dehumidified at room temperature by dry air while maintaining the vacuum at the inlet side of the hydrophobic separation membrane module, Self-diagnosis and self-healing of membrane wetting with control algorithm recovering to pressure (LEP) becomes possible.

[Vacuum membrane distillation method capable of monitoring and controlling membrane wetting index]

4A and 4B are operational flowcharts of a method of monitoring and controlling the film wettability index of a vacuum film distillation system according to an embodiment of the present invention.

4A and 4B, the method for monitoring and controlling the film wettability index of the vacuum film distillation system according to the embodiment of the present invention is characterized in that the film wettability measurement unit 210 shown in FIG. The membrane wettability index is measured at a point of time when the permeation flux is reduced by 15% at the separation membrane surface of the membrane 117 (S201). For example, by calculating the temperature polarization and concentration polarization of the hydrophobic separator for the target influent (raw water), the permeation flux considering the temperature and concentration at the surface of the separator is predicted, and based on the point at which the flux is reduced by 15% The film wettability index can be calculated after a predetermined time. As described later, the calculated film wettability index is stored in a database to monitor the tendency of the film wettability index during the long-term operation, and the dry air is repeatedly supplied in accordance with the trend of the film wettability, .

Next, the inlet side piping of the hydrophobic separation membrane module 117 is filled with a wetting index indicator (S202). At this time, as the wetting index indicator, seawater, chromogenic material or treated water may be used.

Next, the first on / off motor-operated valve 115 installed on the inflow pipe of the hydrophobic separation membrane module 117 is turned off (S203).

Next, the pressure of the inflow pump 114 for supplying the inflow water stored in the inflow water reservoir 113 to the inflow pipe is gradually increased (step S204) so that the maximum pressure is within 3 bar. In other words, the inflow pump 114 gradually pressurizes the inflow pump 114 in stages so that the maximum pressure of the inflow pump 114 for supplying inflow water stored in the inflow water reservoir 113 to the inflow pipe is within 3 bar, Select the point of time when the wetting is accelerated. Specifically, a pressure condition in which a pressure higher than a liquid permeation pressure (LEP) is applied to the hydrophobic separation membrane according to the pressure of the inflow pump 114, thereby accelerating the wetting of the membrane, is checked, and the membrane wetting of the initial hydrophobic separation membrane It is possible to early determine whether or not the film is wetted by applying a pressure corresponding to 80% of the pressure condition at the time of acceleration.

Next, a transparent tube (not shown) installed in the permeate side pipe of the hydrophobic separation membrane module 117 is observed to monitor the pressure of the inflow pump 114 at the time when bubbles are generated (S205). Specifically, a transparent tube is provided on one side of the permeate side pipe of the hydrophobic separation membrane module 117 to increase the pressure in each step, so that the bubble, which is a time point at which the air velocity rapidly accelerates from incomplete pores due to film wettability of the hydrophobic separation membrane, The time point at which the film wetting is accelerated can be selected.

Next, when seawater is used as the wetting index indicator, the permeate side salt concentration is measured by the TDS measuring device 123, and the time when the TDS change occurs is checked (S206). When a chromogenic material is used as the wetting index indicator, a UV absorbance (not shown) of the permeation side salt concentration is measured and a point of time when the absorbance value changes is confirmed (S207).

Next, the film wettability determination unit 220 determines whether the initial number of wet paper sheets is changed by 50% or whether the measured wet paper water number is smaller than the predetermined wettability index (S208).

Next, the first and second on / off electric valves 115 and 119 before and after the hydrophobic separator module 117 are operated when the initial number of the wet paper is changed by 50% or the measured wet paper number is smaller than the predetermined wetting index. (S209). At this time, if the number of the initial wetted paper is not changed by 50% or the measured wetted paper number is not smaller than the preset wetting index, the hydrophobic separation membrane module 117 of the vacuum film distillation system according to the embodiment of the present invention is continuously operated (S213 ).

Subsequently, the first and second on / off electromotive valves 115, 119 before and after the hydrophobic separation membrane module 117 are turned off, and the vacuum pump 127 is controlled under the control of the vacuum pump and the dry air valve control unit 260. Then, To keep the inflow side of the hydrophobic separation membrane module 117 at a vacuum (S210).

Next, the dry air supply unit 116 is operated under the control of the vacuum pump and the dry air valve control unit 260 while the inflow side of the hydrophobic separation membrane module 117 is kept vacuum, and the inflow of the hydrophobic separation membrane module 117 The membrane wetting index measuring unit 210 measures the film wettability index of the hydrophobic membrane module 117 by re-

Next, the film wetting determination unit 220 determines whether the determination unit 220 is recovered to 80% or more of the initial wetting index or recovered to a set value or more (S212).

Next, in the case where the initial wetting index is recovered to 80% or more or recovered to a set value or more, the hydrophobic separation membrane module of the vacuum film distillation system according to the embodiment of the present invention is continuously operated (S213). If the initial wetting index is not recovered to 80% or more than the initial wetting index, or if the initial wetting index is not recovered to the predetermined value or more, the step S211 is repeated until the initial wetting index is recovered to 80% .

Meanwhile, FIG. 5 is a diagram illustrating operation results of a vacuum film distillation system capable of monitoring and controlling the film wettability index according to an embodiment of the present invention. In the vacuum film distillation system, And it was recovered to the initial flux and reactivated by bringing dry air in a vacuum state into contact for 10 minutes.

According to the embodiment of the present invention, since the operation algorithm and the controller applied to various water treatment techniques including seawater desalination have a self-diagnosis function and a healing function for the membrane wetting phenomenon with the built-in membrane distillation technology, It is possible to improve the recovery rate and provide the convenience of operation.

Also, as an embodiment of the present invention, a vacuum film distillation system and method capable of monitoring and controlling the film wettability index and the method thereof have been described. However, the present invention can be applied to other membrane distillation systems other than the vacuum film distillation system.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: Vacuum membrane distillation system
200: Membrane wetting index monitoring and control unit
111: steam generator
112: first thermometer
113: Influent storage tank
114: inflow pump
115: first ON / OFF electric valve
116: Dry air supply
117: Hydrophobic separator module
118: Flowmeter
119: second ON / OFF electric valve
120: Heat exchanger
121: Cooling water storage tank
122: second thermometer
123: TDS meter
124: Pressure gauge
125: treated water storage tank
126: Third on / off electric valve
127: Vacuum pump
128: Fourth on / off electric valve
129: De-wetting storage tank
130: Fifth on / off electric valve
131: Sixth on / off electric valve
210: Membrane wettability index measuring section
220: Film wetting degree judging unit
230: Permeate flow rate and water quality change measuring part
240: Operation continuity determination unit
250: Vacuum pressure and dry air injection time determination unit
260: Vacuum pump and dry air valve control

Claims (16)

1. A vacuum film distillation system for controlling the phenomenon of film wettability caused by the use of a hydrophobic separation membrane of a vacuum film distillation system applied to a water treatment apparatus for a long period of time or by exposure to a film pollution inducing substance,
And includes a hydrophobic separation membrane module 117, an influent storage tank 113, a steam generating unit 111, a TDS measuring unit 123, a flow meter 118, a dry air supply unit 116 and a process water storage tank 125, A vacuum film distillation system (100) installed to generate steam by passing steam through a difference in vapor pressure generated between inflow water at room temperature as a driving force; And
The membrane wetting index of the hydrophobic separation membrane module 117 is measured to monitor the membrane wettability index, the water quality change and the permeation flux of the treated water are measured, and the measured membrane wettability index or the measured permeation flow rate And a film wettance index monitoring and control unit (200) for judging the degree of film wettability of the hydrophobic separation membrane according to a change in water quality and controlling the vacuum pressure and dry air to be supplied to the hydrophobic separation membrane module (117) The wetting index monitoring and control unit 200 controls the supply of dry air or the vacuum to the inflow side of the hydrophobic separation membrane module 117 according to the membrane wettability index to prevent wetting of the surface of the hydrophobic separation membrane,
The membrane wettability monitoring and control unit 200 calculates the temperature polarization and concentration polarization of the hydrophobic separation membrane relative to the target influent water (raw water), predicts the permeation flux considering the temperature and concentration on the surface of the separation membrane, Wherein the film wettability index is calculated after a predetermined time based on a time point at which the film wettability is reduced by 15% or more. The vacuum film distillation system (100) according to claim 1, wherein the vacuum film distillation system (100)
A hydrophobic separation membrane module (117) installed to generate steam by passing steam through a difference in vapor pressure generated between seawater and an influent of normal temperature as a driving force;
An inflow water reservoir 113 for supplying inflow water by the inflow pump 114;
A steam generator 111 installed on an inflow side of the hydrophobic separation membrane module 117 to supply steam to the inflow water;
A TDS meter 123 installed on the permeate side of the hydrophobic separation membrane module 117 to measure total dissolved solids (TDS);
A flow meter 118 installed on the permeate side of the hydrophobic separation membrane module 117 for measuring the flow rate of the treated water;
A dry air supply unit (116) for supplying dry air to the surface or inside of the hydrophobic separation membrane under the control of a vacuum pump and a dry air valve control unit (260); And
And a process water reservoir (125) storing and discharging the process water that has passed through the hydrophobic separation membrane module (117). 3. The apparatus of claim 2, wherein the membrane wettling index monitoring and control unit (200)
A membrane wettability measurement unit 210 installed at an inlet side of the hydrophobic separation membrane module 117 to measure the membrane wettability index to monitor a membrane wettability index of the separation membrane of the hydrophobic separation membrane module 117;
A permeate flow rate and water quality change measuring unit 230 for measuring the water quality change according to the flow rate of the treated water measured by the flow meter 118 and measuring the permeate flow rate according to the TDS measured by the TDS meter 123;
The membrane wetting index measured by the membrane wettability measuring unit 210 and / or the membrane wetting degree of the hydrophobic separating membrane according to the permeation flux and the water quality change measured by the permeation flux and water quality change measuring unit 230 A wetness determination unit 220; And
The vacuum pump 127 is operated to control the vacuum pressure to be applied to the hydrophobic separation membrane module 117 and the dry air supply section 116 is operated to spray the dry air to the hydrophobic separation membrane module 117 A vacuum pump and a dry air valve controller 260,
A vacuum film distillation system capable of monitoring and controlling the film wettability index. The method according to claim 1,
The membrane wettling index monitoring and control unit 200 monitors the pressure at which the wetting of the hydrophobic separation membrane at the initial stage of operation of the hydrophobic separation membrane module 117 is accelerated and monitors the pressure at which the membrane wetting is generated, And the film wettability index is expressed by the liquid permeation pressure (

), ≪ / RTI >

here,

Represents the shape coefficient of the separation membrane,

Represents the surface tension of the liquid,

Represents the contact angle between the separation membrane and the liquid,

Wherein the membrane wettability index indicates the maximum pore size. delete The method according to claim 1,
The membrane wettling index monitoring and control unit 200 increases the pressure of the inside of the hydrophobic separation membrane module 117 step by step to select the time point at which the membrane wetting is accelerated, Wherein the film wettability index is measured and controlled. The method according to claim 1,
One side of the permeation side pipe of the hydrophobic separation membrane module 117 is installed as a transparent tube and the pressure is increased step by step so that the bubble which is the time point at which the air flow rate rapidly accelerates from incomplete pores due to the membrane wetting phenomenon of the hydrophobic separation membrane And selecting a time point at which the bubble is generated as a point at which the film wetting is accelerated. A vacuum film distillation method for controlling a film wettability phenomenon which is caused by a hydrophobic separation membrane of a vacuum film distillation system applied to a water treatment apparatus for a long period of time or caused by exposure of a film contamination inducing substance,
a) measuring the membrane wettability index at the membrane surface of the hydrophobic membrane module (117) by the membrane wettability measurement unit (210);
b) filling the inlet side piping of the hydrophobic separation membrane module (117) with a wetting index indicator;
c) gradually pressurizing the inflow pump 114 for turning off the first on / off motor-operated valve 115 provided on the inflow pipe of the hydrophobic separation membrane module 117 and supplying inflow water to the inflow pipe, ;
d) monitoring a pressure of the inflow pump (114) at a time point at which bubbles are generated by observing a transparent pipe installed in the permeate side pipe of the hydrophobic separation membrane module (117);
e) determining whether the membrane wettability determination unit (220) determines the membrane wettability of the separation membrane of the hydrophobic separation membrane module (117);
f) If it is determined that the membrane wetting phenomenon occurs in the separation membrane of the hydrophobic separation membrane module 117, the first and second on / off transmission valves 115 and 119 before and after the hydrophobic separation membrane module 117 are turned off, Operating the vacuum pump 127 under the control of the vacuum pump and dry air valve control unit 260 to maintain the inflow side of the hydrophobic separation membrane module 117 in vacuum;
g) The dry air supply unit 116 is operated under the control of the vacuum pump and the dry air valve control unit 260 to inject dry air into the inflow side of the hydrophobic separation membrane module 117 so that the surface and inside of the hydrophobic separation membrane Dehumidifying; And
h) re-measuring the membrane wettability index in the membrane wettability measurement unit 210 and checking whether the membrane wettability determination unit 220 has recovered the membrane wettability
Wherein the film wettability index of the vacuum film separator is in the range of from about 1 to about 10. 9. The method of claim 8,
In the step a), the temperature polarization and the concentration polarization of the hydrophobic separator for the target influent water (raw water) are calculated to predict the permeation flux considering the temperature and the concentration at the surface of the separator, Wherein the film wettability index is calculated after a predetermined time. 10. The method of claim 9,
The calculated film wettability index is stored in a database to monitor the tendency of the film wettability index during a long-term operation, and dry air is circulated repeatedly according to the tendency of the film wettability index to prevent film wetting in advance A vacuum film distillation method capable of monitoring and controlling film wettability index. 9. The method of claim 8,
In step c), the inflow pump 114 gradually pressurizes the inflow pump 114 in a stepwise manner so that the maximum pressure of the inflow pump 114 for supplying inflow water stored in the inflow water reservoir 113 to the inflow pipe is within 3 bar, And a large pressure point is selected as a time point at which the wetting is accelerated. A vacuum film distillation method capable of monitoring and controlling a film wettability index. 12. The method of claim 11,
In step d), a pressure condition in which a pressure higher than a liquid permeation pressure (LEP) is applied to the hydrophobic separation membrane according to the pressure of the inflow pump 114 to accelerate the membrane wetting is checked, and the pressure of the initial hydrophobic separation membrane Wherein the film wettability is determined early by applying a pressure corresponding to 80% of the pressure condition at the time when the wetting is accelerated, whereby the film wettability can be monitored and controlled. 9. The method of claim 8,
In step d), a transparent tube is installed on one side of the permeate side pipe of the hydrophobic separation membrane module 117 to increase the pressure in each step so that the bubble, which is a time point at which the air velocity rapidly accelerates from incomplete pores due to membrane wetting phenomenon of the hydrophobic separation membrane Is selected as a time point at which film wetting is accelerated. A vacuum film distillation method capable of monitoring and controlling a film wettability index. 9. The method of claim 8,
When the seawater is used as the wetting index indicator in the step b), the time of the TDS change is measured by measuring the permeate side salt concentration with the TDS measuring device 123 in the step d), or the time when the TDS is changed, Wherein a chromaticity-inducing substance is used, the UV absorbance of the permeate side salt concentration is measured in the step d), and a point of time when a change in the absorbance value is observed is confirmed, and a vacuum film distillation method capable of monitoring and controlling the film wettability index . 9. The method of claim 8,
In step e), the film wettability determination unit 220 determines whether the initial wetness number is changed by 50% or whether the measured wetness number is smaller than a predetermined wetting index. And a controllable vacuum film distillation method. 9. The method of claim 8,
Wherein in step h), the controller determines whether the film wettability is restored to 80% or more than the initial wettability index or recovered to a preset value or more. Membrane distillation method.

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