JP5470864B2 - Water quality reforming system and water quality reforming method - Google Patents

Description

  The present invention relates to a water quality reforming system and a water quality reforming method for reforming the quality of water supplied to equipment such as a boiler using a separation membrane device such as a membrane filtration device.

  Controls the number of reverse osmosis membrane units operated, a plurality of reverse osmosis membrane units connected in parallel to each other to remove impurities in the treated water and supply them to equipment, a pump for supplying the treated water to the reverse osmosis membrane units Patent Documents 1 and 2 disclose a water quality reforming system including a control unit that performs the above-described control.

  In the patent document 1, the applicant of the present application includes a reverse osmosis membrane portion on the upstream side of the water supply line to the thermal equipment, a pump for supplying water to the filtration membrane portion on the upstream side, and a membrane on the downstream side. After removing the corrosion-promoting component from the reverse osmosis membrane part of the water to be treated and degassing the dissolved gas at the membrane type deaeration part, multiple reverse osmosis membrane parts are connected to the water supply line in parallel. A water quality reforming system in which a pump is arranged for each reverse osmosis membrane section, and further, a control valve capable of preventing backflow is arranged on the downstream side of each reverse osmosis membrane section. Based on the temperature of the feed water, the operation and stoppage of the pumps arranged for each reverse osmosis membrane part are selectively performed based on the temperature of the feed water so that both the corrosion promotion component residual allowable value and the dissolved gas residual allowable value are satisfied. Proposing a water quality reforming system that controls the number of reverse osmosis membrane units in operation To have.

  Further, in Patent Document 2, when water to be treated is boosted and supplied to a plurality of reverse osmosis membrane units provided in parallel, and a reverse osmosis treatment device for obtaining treated water as permeated water is operated, A water quality reforming system that controls the number of operating reverse osmosis membrane units according to the temperature of water and / or the quality of treated water is proposed.

JP 2005-279462 A JP 2001-239134 A

In the water quality reforming systems shown in Patent Document 1 and Patent Document 2 , the system performance can be optimized because the number of units is controlled without considering the membrane characteristics of membrane degradation and membrane clogging. Not.

  It is an object of the present invention to provide a water quality reforming system capable of optimizing system performance and uniformizing clogging and deterioration of each separation membrane section in a water quality reforming system for controlling the number of operating separation membrane sections. And Here, optimization means satisfying the required water quality and performing maximum energy saving operation.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is a plurality of separation membranes connected in parallel to each other to remove impurities in water to be treated and supply the treated water to equipment. And a pump capable of controlling the number of rotations provided for each separation membrane unit and supplying treated water to each separation membrane unit, and controlling the number of operation of the separation membrane units, and the number of rotations of each pump A water quality reforming system comprising a control means for individually controlling the water temperature detecting means for detecting the water temperature, and a first membrane performance detecting means for detecting the membrane performance of each of the separation membrane portions by a permeation flux, A second membrane performance detecting means for detecting the membrane performance of each separation membrane part by a reference ion permeability at a reference water temperature and a reference rated flow rate; a required water quality determining means for determining a required water quality of the device for treated water; Treatment water for separation membrane A flow rate detecting means for detecting an amount, each separation membrane of the treatment water flow rate and water quality table of treated water quality of the water temperature as a parameter, as well as the reference temperature and stored in advance stores an initial reference ion transmittance at the reference rated flow Means for setting the priority order of the separation membrane unit based on the permeation flux by the first membrane performance detecting means, and the detection reference ion permeability by the second membrane performance detecting means. seeking the value the initial reference ion permeability value divided by deterioration correction coefficient of, by multiplying the deterioration correction coefficient to the value of the treated water quality of the water quality table, and correcting the respective quality characteristic table , Based on the water temperature by the water temperature detecting means and the required water quality by the required water quality judging means, the request from each water quality characteristic table corrected for each separation membrane unit. Calculating a required water quality maintenance flow rate for obtaining treated water quality satisfying the quality, setting a relationship between the priority order and the required water quality maintenance flow rate, determining an increase / decrease in the number of operating units of the separation membrane unit, and operating number When it is determined to increase or decrease, the separation membrane unit with higher priority is prioritized for operation and / or the separation membrane unit with lower priority during operation is stopped, and the separation membrane in operation And a step of controlling the number of revolutions of the pump so that the detected flow rate of the flow rate detection means becomes the required water quality maintenance flow rate.

According to the first aspect of the present invention, the performance of the system can be optimized, and the clogging and deterioration of each separation membrane can be made uniform. Moreover, the rotation speed of the pump can be controlled to be low, and energy saving can be realized.

The invention according to claim 2 removes impurities in the water to be treated and supplies the treated water to the apparatus, and includes a plurality of separation membrane parts connected in parallel to each other, and the water to be treated provided for each of the separation membrane parts. A pump capable of controlling the number of rotations supplied to each separation membrane unit, a membrane deaeration device connected to the downstream side of the separation membrane unit, and controlling the number of operation of the separation membrane unit, and rotating each pump A water quality reforming system comprising a control means for individually controlling the number of water, a water temperature detecting means for detecting the water temperature, and a first membrane performance detecting means for detecting the membrane performance of each of the separation membrane sections by a permeation flux The second membrane performance detecting means for detecting the membrane performance of each separation membrane part by the reference ion permeability at the reference water temperature and the reference rated flow rate, the required water quality determining means for determining the required water quality of the device for the treated water, The flow rate of treated water in each separation membrane A flow rate detecting means for output, said each separation membrane of the treatment water flow rate and water quality table of treated water quality of the water temperature as a parameter, and storage means for previously storing an initial reference ion transmittance at the reference temperature and the reference rated flow And the control means sets the priority order of the separation membrane part based on the permeation flux by the first membrane performance detection means, and the value of the detection reference ion permeability by the second membrane performance detection means the search of the initial reference ion permeability value deterioration correction coefficient divided by the, by multiplying the deterioration correction coefficient to the value of the treated water quality of the water quality table, and correcting the respective quality characteristic table, wherein Based on the water temperature by the water temperature detecting means and the required water quality by the required water quality judging means, the required water quality is obtained from each water quality characteristic table corrected for each separation membrane section. Calculating the required water quality maintenance flow rate for obtaining the treated water quality, setting the relationship between the priority order and the required water quality maintenance flow rate, determining the increase / decrease in the number of operating separation membrane units, and increasing the number of operating water Alternatively, when it is determined to decrease, the separation membrane unit with higher priority is prioritized for operation and / or the separation membrane unit with lower priority during operation is stopped, and the separation membrane unit in operation And a step of controlling the number of revolutions of the pump so that the detected flow rate of the flow rate detection means becomes the required water quality maintenance flow rate.

According to the second aspect of the present invention, since the separation membrane portion having high membrane performance is operated with priority, the performance of the system is optimized with respect to the filtered water quality, and the clogging and deterioration of each separation membrane portion are made uniform. be able to.

Invention according to claim 3, in claim 2, wherein the membrane consists deaerator plurality of degassing membrane unit connected in parallel with each other, the flow of treated water to the water supply line of the respective degassing membrane unit A third membrane performance detecting means for detecting the membrane performance of each deaeration membrane part by the dissolved oxygen concentration downstream of each deaeration membrane part, wherein the control means comprises the first based on the dissolved oxygen concentration by the three membrane performance detection means, determining the membrane performance of the degassing membrane unit, comprising the steps of: determining an increase or decrease in number of operating the degassing membrane unit determines that the number of operating units increase or decrease In some cases, the operation is performed in preference to the deaeration membrane part having a high membrane performance and / or the step of giving priority to the deaeration membrane part having a low membrane performance is stopped.

According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, the deaeration membrane part having high membrane performance is operated with priority, so that the system performance is optimized with respect to the deaeration water quality. Thus, there is an effect that the clogging and deterioration of each deaeration membrane part can be made uniform.

Furthermore, the invention according to claim 4 is provided with a plurality of separation membrane portions connected in parallel to each other to remove impurities in the water to be treated and supply the treated water to the equipment, and to be treated for each of the separation membrane portions. A water quality reforming method comprising: a pump capable of controlling the number of revolutions for supplying water to each separation membrane unit; and individually controlling the number of revolutions of each pump and controlling the number of operating separation membrane units. In addition, the water quality characteristic table of the treated water quality using the treated water flow rate and the water temperature of each separation membrane unit as parameters, and the initial reference ion permeability at the reference water temperature and the standard rated flow rate are stored in advance, and the separation membrane unit detecting the membrane performance flux, and the reference ion transmittance at the reference temperature and the reference rated flow, based on the detected flux, and setting a priority of the separation membrane, the detection reference The value of the on transmittance was divided by the value of the initial reference ion permeability calculated deterioration correction factor, by multiplying the deterioration correction coefficient to the value of the treated water quality of the water quality table, corrects the respective quality characteristic table Each of the separation membrane portions corrected based on the detected water temperature and the determined required water quality based on the detected water temperature and the determined water quality. Calculate the required water quality maintenance flow rate to obtain the treated water quality that satisfies the required water quality from the water quality characteristic table, set the relationship between the priority order and the required water quality maintenance flow rate, and determine the increase or decrease in the number of operation of the separation membrane unit And when it is determined that the number of operating units is increased or decreased, the separation membrane unit with higher priority is given priority and the separation membrane unit with lower priority during operation and / or operation is given priority. A step of stopping, in the separation membrane during operation, detecting the flow rate of the flow rate detecting means is characterized by executing and controlling the rotational speed of the pump so that the requested quality maintenance flow rate.

According to the invention described in claim 4 , since the separation membrane part with high membrane performance is operated with priority, the system performance is optimized with respect to the water quality, and the clogging and deterioration of each separation membrane part are made uniform. Can do.

According to this invention, the performance of the system can be optimized with respect to water quality, and the clogging and deterioration of each separation membrane can be made uniform.

It is a schematic block diagram of Example 1 of the water quality modification system which implemented this invention. It is a schematic block diagram of the membrane filtration apparatus of the Example 1. It is a flowchart figure which shows the principal part of the control procedure of the Example 1. FIG. It is a flowchart figure explaining the control procedure of the principal part of FIG. It is a figure explaining the relationship between the operation number with respect to the water level of the treated water tank of the Example 1, the setting value of the treated water flow rate of a reverse osmosis membrane part, a priority, and operation / stop. It is a flowchart figure explaining the control procedure of other Example 2 of this invention. It is a schematic block diagram of the membrane filtration apparatus of the Example 2. It is a figure explaining the setting relationship of the flow rate ratio which satisfy | fills the driving | running priority in Example 2 and the required water quality Q1. It is a figure explaining the relationship between the operation pattern with respect to the water level of the treated water tank of the Example 2, and the amount of supplied water. It is the characteristic figure of the permeation | transmission ratio which used the flow rate ratio and water temperature of the Example 2 as a parameter. It is a water quality characteristic figure which made the flow rate ratio and water temperature of the example 2 into a parameter. It is an effective operation pressure characteristic figure which made the flow rate ratio and water temperature of Example 2 the parameter. It is an energy-saving ratio characteristic figure which made the flow rate ratio and water temperature of Example 2 the parameter. It is a flowchart figure explaining the control procedure of other Example 3 of this invention. It is a flowchart figure explaining the control procedure of the principal part of FIG. It is a figure explaining the relationship between the operation pattern with respect to the water level of the treated water tank of the Example 3, and the amount of supplied water. It is a figure explaining the relationship between the driving | running pattern with respect to the water level of the treated water tank in the modification of the Example 3, and the amount of supplied water. It is a schematic block diagram of the other Example 4 of this invention. It is a schematic block diagram of the other Example 5 of this invention.

  An embodiment of the present invention will be described. The embodiment of the present invention is preferably implemented in a water quality reforming system using a filtration treatment unit using a reverse osmosis membrane including a nanofiltration membrane (NF membrane, NF: Nanofiltration) and a deaeration membrane unit using a deaeration membrane. Can do.

(Embodiment 1)
Embodiment 1 of the present invention is a water quality reforming system including the following components. That is, a plurality of separation membrane parts connected to each other in parallel to remove impurities in the treated water and supplying the treated water to the device, a pump for supplying the treated water to each separation membrane part, and the separation membrane part And control means for controlling the number of operating units. The control means is characterized in that when it is determined that the number of operating units is increased or decreased, a separation membrane portion having high membrane performance is used preferentially. Here, use can be rephrased as water flow.

  Here, the water to be treated and the treated water mean water before being treated in each separation membrane section and water after being treated. The separation membrane portion is preferably a reverse osmosis membrane, but a filtration membrane portion using a filtration membrane such as an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane) other than the reverse osmosis membrane, and a treatment target A degassing membrane part using a degassing membrane for degassing water gas components is included. The membrane performance is the initial membrane performance of each separation membrane section (membrane performance measured before product shipment or when a reforming system is installed), and the membrane performance that changes with the operation of each separation membrane section. Includes the degree of membrane clogging and membrane degradation.

  When the separation membrane portion is a reverse osmosis membrane portion, the degree of clogging of the membrane can be detected by the permeation flux, and the degree of deterioration of the membrane can be detected by the removal rate (or permeability). The removal rate and transmittance can be referred to as ion removal rate and ion transmittance, respectively.

  Embodiment 1 shows a system in which a pump is individually provided for each separation membrane section as shown in FIG. 1 of Patent Document 1 and FIG. 2 of Patent Document 1 or FIG. 1 of Patent Document 2. The present invention can be applied to any system in which a common pump is provided for each of the separation membrane parts. The operation and stop of the separation membrane unit is realized by operation and stop of each pump in a system in which a pump is individually provided for each separation membrane unit. In a system provided with a common pump, it is realized by opening and closing a valve provided in series with each of the separation membrane portions.

In the first embodiment, preferably, each pump is configured to be able to control the rotational speed . And control of the operation number of the said separation membrane part preferably increases / decreases the operation number of the said separation membrane part according to the water temperature of a to-be-processed water and / or the quality of the treated water. More preferably, the control of the number of operating separation membrane units controls the number of rotations of the pump according to the temperature change of the water to be treated so that the flow rate and quality of the treated water are within a predetermined range, and This is done by increasing or decreasing the number of operating separation membrane units.

  In the first embodiment, the membrane performance representing the clogging and deterioration of each separation membrane section is periodically detected by the membrane performance detecting means. And if the said control means determines the increase / decrease in the number of operation | movement of the said separation membrane part, it will drive preferentially the separation membrane part with the high membrane performance detected by the said membrane performance detection means. As a result, the separation membrane part having relatively high membrane performance is operated. The treated water treated by the separation membrane unit is supplied to equipment used such as a boiler.

  According to the first embodiment, since the separation membrane portion with high membrane performance detected by the membrane performance detecting means is used preferentially, the performance of the system is optimized with respect to water quality, and the membrane of each separation membrane portion is clogged. And deterioration can be made uniform. Also, when performing membrane cleaning and membrane exchange all at once due to the uniform clogging and deterioration of the membrane, it can be performed with the most of the membrane capacity, and the interval between membrane cleaning and membrane exchange can be extended. Can be taken.

  When the separation membrane part is a filtration membrane part and the membrane performance is the degree of clogging of the membrane, the rotation of the pump is performed to obtain the same treated water flow rate by operating the separation membrane part with higher membrane performance in preference. Since the number can be lowered, energy saving is realized.

  And in this Embodiment 1, the following three aspects are included as an aspect which "uses the separation membrane part with the high membrane performance detected by the said membrane performance detection means preferentially."

  In the first mode, when it is determined that the number of operating units is increased, the separation membrane unit that is stopped is preferentially operated with a high membrane performance detected by the membrane performance detecting means. In this aspect, when there are a plurality of separation membrane units whose operation is stopped, the separation membrane unit having the higher membrane performance is selected and the operation is sequentially started.

  Moreover, a 2nd aspect is an aspect which gives priority and stops the thing with the low membrane performance detected by the said membrane performance detection means among the said separation membrane parts in operation when it determines with the number of operation reduction. In this aspect, when there are a plurality of separation membrane portions in operation, the separation membrane portion having the lower membrane performance is selected and sequentially stopped.

  Furthermore, when the third aspect determines that the number of operating units is increased, the separation membrane unit that is stopped is preferentially operated with the high membrane performance detected by the membrane performance detecting means, and the number of operating units is decreased. It is an aspect which preferentially stops the thing with the said low membrane performance among the said separation membrane parts in operation when it determines with. In this aspect, when there are a plurality of separation membrane units in operation stop, the operation is started by selecting the separation membrane unit having the higher membrane performance, and when there are a plurality of separation membrane units in operation, the membrane Select the separation membrane with the lower performance and stop.

  Here, the components of the first embodiment will be described. The device is a device in which treated water treated by the separation membrane unit is used, and is a boiler or the like.

  Each of the separation membrane portions is preferably a reverse osmosis membrane portion that removes a filtration component by a reverse osmosis membrane such as a nanofiltration membrane, but may be a filtration device having other filtration membrane portions, and has a specific structure. It is not limited to a filtration device. Moreover, the said separation membrane part can be made into the deaeration membrane part which deaerates gaseous components, such as dissolved oxygen in the to-be-processed water as an impurity.

  The pump preferably has a controllable rotational speed and is not limited to a specific pump. The rotational speed is preferably controlled by an inverter.

  The membrane performance detecting means detects the membrane performance of each separation membrane section. The treated water quality of the separation membrane part (reverse osmosis membrane part and deaeration membrane part) varies depending on the water temperature, operating pressure (flow rate), membrane performance (including individual differences), and the like. In addition, the reverse osmosis membrane changes depending on the raw water quality (ion balance), and the deaeration membrane portion also changes depending on the degree of vacuum. The difference between the solids is a difference in the initial performance of the film caused by manufacturing. And membrane performance falls with time in addition to individual differences, and water quality deteriorates. This decrease in membrane performance may be due to clogged filtration components or due to membrane degradation. The clogging is recovered to some extent by regeneration (chemical cleaning), but the deterioration of the membrane is chemical deterioration, physical deterioration, aging deterioration due to chlorine deterioration or water temperature (high temperature), and is not recovered by regeneration (chemical cleaning).

  The membrane performance detecting means detects the state of membrane performance due to membrane clogging and membrane degradation including the individual differences. When the separation membrane part is a reverse osmosis membrane part, the membrane performance can be detected by the quality of treated water (electrical conductivity), the removal rate (the ratio of the filtered component removed) or the permeability, the permeation flux, and the like. The membrane performance relating to the degree of membrane degradation can be detected by the treated water quality and the permeability (or removal rate), and the membrane performance relating to the degree of membrane clogging can be detected by the permeation flux. In this case, when the membrane performance is regarded as the degree of deterioration of the membrane, it is possible to obtain treated water with high quality of treated water by operating with priority given to the separation membrane portion having high membrane performance, and clog the membrane performance. In this case, energy saving can be realized by giving priority to the operation of the separation membrane part having high membrane performance.

  When the separation membrane part is a deaeration membrane part, the membrane performance can be achieved by the DO value of the treated water, the flow rate, the differential pressure (the difference in water pressure between the inlet side and the outlet side of the deaeration membrane part), and the like. In this case, by preferentially operating the degassing membrane part with good (high) DO value of treated water, treated water with high quality of treated water can be obtained, and a vacuum pump that drives each membrane degassing part Energy saving can be realized by reducing the number of operating units.

The transmittance will be described. The membrane of each of the filtration membrane parts has an initial reference performance due to a solid difference. This initial reference performance can be expressed by an initial reference transmittance. The initial reference transmittance can be obtained by the control unit by passing water at the start of use of the system. However, before the system is shipped, the initial reference transmittance is obtained and input for each filtration membrane unit. be able to.
Transmittance (%) = 100−removal rate (%). The transmittance and the removal rate represent water quality, and are numerical values representing the membrane performance due to the solid difference and deterioration of the membrane.

The permeability is affected by the water temperature and pressure (flow rate). Therefore, the reference transmittance under actual operating conditions can be obtained by the following equation.
Reference transmittance under actual operating conditions = Reference transmittance (25 ° C, reference rated flow rate) x water temperature correction factor X × pressure (flow rate) correction factor

When the filtration membrane portions are actually used, the removal rate may be deteriorated due to deterioration of the membrane or the like, so that the reference transmittance changes with time. Therefore, the reference transmittance under actual operating conditions considering degradation is represented by the following equation.
Reference transmittance under actual operating conditions = reference transmittance (25 ° C, reference rated flow rate) x water temperature correction factor x pressure (flow rate) correction factor x deterioration correction factor Y
This deterioration correction coefficient Y can be obtained by the following equation.
Deterioration correction coefficient Y = current reference transmittance / initial reference transmittance This deterioration correction coefficient Y may be obtained in real time or may be a constant coefficient in advance depending on the water passage time. For example, the deterioration correction coefficient is 1.1 after 1000 hours of water flow.
The removal rate is obtained by dividing the difference in electric conductivity between the inlet side and the outlet side of each membrane filtration part by the electric conductivity on the inlet side.

  The permeation flux is an index indicating the water permeation performance of the membrane, that is, the clogging state of the membrane, and can be obtained by the method described in JP-A-2008-55336. In other words, the amount of water permeating through the unit membrane area per unit time is converted under standard temperature conditions as per unit membrane differential pressure. If this is expressed by an equation, it can be expressed by the following equation 1.

Permeation flux (L / m ² · h · MPa) = instantaneous flow rate of treated water / [{inlet operating pressure-(device differential pressure ÷ 2)-outlet back pressure-osmotic pressure} x temperature correction coefficient x membrane area] ... ............ Formula 1

Here, treated water instantaneous flow rate: detected value with treated water flow meter (unit: L / h), inlet operating pressure: detected value with inlet operating pressure sensor (unit: MPa), device differential pressure: set value (unit) : MPa), outlet back pressure: set value (unit: MPa), osmotic pressure: set value (unit: MPa), temperature correction coefficient: A (function of feed water temperature detected by feed water temperature sensor), membrane area: set Value (unit: m ² ).

  Data for calculating the permeation flux (the instantaneous flow rate of treated water, the inlet operating pressure, and the feed water temperature) is detected by each data measurement (detection) means. The sampling of these data is performed at the timing when the filtration performance of the reverse osmosis membrane portion is stabilized by the control means. The device differential pressure, osmotic pressure, and outlet back pressure are not necessarily set values, and may be obtained by detecting in real time with a sensor. The permeation flux is preferably an average value of a plurality of permeation fluxes obtained by performing the sampling a plurality of times.

Further, the expression for expressing the permeation flux (L / m ² · h · MPa) is not limited to Expression 1 but can also be expressed by Expression 2 below.
Treated water instantaneous flow rate / [{(Inlet pressure−Outlet pressure) ÷ 2-Outlet back pressure−Osmotic pressure} × Temperature correction coefficient × Membrane area] …… Equation 2
Moreover, in the said Formula 1 or the said Formula 2, when the influence of an outlet back pressure or an osmotic pressure can be disregarded (constant), these can be deleted.

The control means has a function of preferentially using a separation membrane section having a high membrane performance at the time of determination when it is determined that the number of operating units is increased or decreased. The membrane performance is preferably detected periodically or continuously while the system is operated by the membrane performance detection means. However, it is also possible to detect only the initial membrane performance and use the separation membrane portion having a high initial membrane performance with priority. In this case, the membrane performance detection means need not always be provided in the reforming system of the first embodiment, and may be any device that can be used only when detecting the initial membrane performance. Moreover, although the said control means is provided for every said separation membrane part, it can comprise so that it may control by the controller common to each said separation membrane part.

(Embodiment 2)
The present invention is not limited to the above-described first embodiment. For example, the present invention is applied to a system similar to the water quality reforming system shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2005-279462. It can be set as form 2.

  In this second embodiment, a plurality of filtration membrane parts connected to each other in parallel to remove impurities in the water to be treated and supplied to the equipment, and the water to be treated provided to each of the filtration membrane parts are supplied to the filtration membrane part. A water quality reforming system comprising: a pump to be supplied; a membrane deaeration device connected to a downstream side of the filtration membrane portion; and a control means for controlling the pump, wherein the control means When the increase / decrease in the number of operating units is determined and it is determined that the number of operating units is increased or decreased, the water membrane reforming system is characterized by preferentially using the filtration membrane unit having high membrane performance.

  Each of the pumps of the second embodiment is preferably configured such that the rotational speed can be controlled. Further, the control means controls the number of operation of the filtration membrane units by selectively performing operation / stop of the pumps arranged for each filtration membrane unit, and controls the rotation speed of each pump. . And also in this Embodiment 2, like the said Embodiment 1, when the said control means determines with the number of operation increase or reduction, it preferentially operates the filtration membrane part with high membrane performance.

  The flow rate control of the second embodiment will be described more specifically. The flow rate of the feed water, the temperature of the feed water, the residual value of the corrosion promoting component in the filtered water after filtering the corrosion promoting component by the filtration membrane unit, and the removal The relationship between the dissolved gas remaining value in the permeated water after degassing the dissolved gas at the gas membrane part is determined in advance, the corrosion promoting component remaining allowable value and the dissolved gas remaining allowable value are determined, and the water supply line is Detecting the temperature of the flowing feed water, and operating / stopping the pumps arranged for each filtration membrane unit so that both the corrosion promotion component residual allowable value and the dissolved gas residual allowable value are satisfied based on the temperature of the supplied water. The flow rate of feed water is controlled by selectively performing and controlling the rotation speed of each pump.

  The first and second embodiments include the following water quality reforming method. The water quality reforming method includes a plurality of filtration membrane parts connected in parallel to remove impurities in the treated water and supplying the treated water to the apparatus, and a pump for supplying the treated water to each of the filtration membrane parts. A water quality reforming method for controlling the number of operation of the filtration membrane units, the first step of detecting the membrane performance of each of the filtration membrane units, and the second of determining increase / decrease in the number of operation of the filtration membrane units And a third step of preferentially using the filtration membrane part having a high membrane performance detected in the first step when it is determined in the second step that the number of operating units is increased or decreased. To do.

  In the water quality reforming method, the first step is preferably performed at all times during operation of the water quality reforming system for performing the water quality reforming method, but is performed only at the start of use of the water quality reforming system. can do.

  According to this water quality reforming method, the performance of the system can be optimized with respect to the water quality, and the clogging and deterioration of each filtration membrane can be made uniform. In addition, when each pump is capable of controlling the rotation speed, the filtration membrane portion with high performance is given priority to operation and / or the separation membrane portion with low membrane performance is given priority to stop. When obtaining a predetermined treated water flow rate and / or treated water quality in each filtration membrane part, the number of revolutions of the pump can be lowered, and the power consumption of the pump can be reduced.

Further, in the second embodiment, preferably, the membrane deaerator is configured by a plurality of deaeration membrane units connected in parallel to each other, and the flow of treated water is controlled in the water supply line of each of the deaeration membrane units. The control means determines increase / decrease in the number of operating units of the deaeration membrane part, and when it is determined to increase or decrease the number of operating units, the control unit preferentially uses the deaeration film unit having high membrane performance, that is, The degassing membrane part with high membrane performance is given priority for operation and / or the deaeration membrane part with low membrane performance is given priority and stopped.

  In this Embodiment 2, the number of rotations of the pump can be reduced by detecting the membrane performance of the reverse osmosis membrane part with a permeation flux and preferentially passing the reverse osmosis membrane part with a high permeation flux. , Energy saving can be realized. Moreover, the membrane performance of the reverse osmosis membrane part is detected by the treated water quality or the removal rate, and the filtered water quality is high by preferentially setting the treated water quality or the reverse osmosis membrane part having a high removal rate. Can be realized.

  Further, when the degassing membrane part is degassed by a vacuum pump, energy saving can be realized by reducing the number of vacuum pumps by reducing the number of operating degassing membrane parts, High deaerated water quality can be realized by detecting the membrane performance by the treated water quality and preferentially bringing the deaerated membrane part having the high treated water quality into a water passage state.

(Embodiment 3)
The present invention is not limited to the first embodiment, but includes a third embodiment in which the separation membrane is the degassing membrane.

  The third embodiment includes a plurality of deaeration membrane parts connected in parallel to remove gas components as impurities in the water to be treated and supplying the treated water to the equipment, and each deaeration membrane part to be treated water. And a control means for controlling the number of operating deaeration membrane units. The control means is a water quality reforming system that preferentially uses a deaeration membrane part having high membrane performance when it is determined that the number of operating units is increased or decreased. The meaning of “use” is the same as in the first embodiment.

  In this third embodiment, treated water with high deaeration is supplied by preferentially using a deaeration membrane part with high membrane performance, that is, with high deaeration of treated water (DO value is low). it can.

  Embodiment 1 of the water quality reforming system of the present invention will be described below with reference to the drawings. The first embodiment is a system that controls the number of operating reverse osmosis membrane units as separation membrane units according to the present invention so that the treated water flow rate of each reverse osmosis membrane unit becomes a predetermined flow rate according to the water level of the treated water tank. It is. FIG. 1 is a schematic configuration diagram of the first embodiment. FIG. 2 is a schematic configuration diagram of each membrane filtration device of the first embodiment. FIG. 3 is a flowchart for explaining the control procedure of the first embodiment. FIG. 4 is a flowchart for explaining the control procedure of the main part of FIG. FIG. 5 is a view for explaining the relationship among the number of operating water tanks relative to the water level, the set value of the treated water flow rate of the reverse osmosis membrane section, the operating priority, and the operation / stopping.

  In FIG. 1, a water quality reforming system 1 of Example 1 is a water quality reforming system for reforming the quality of feed water supplied to a thermal device 2, and a feed water line 3 for supplying feed water to the thermal device 2. And the activated carbon filtration device 4 connected to the water supply line 3, the soft water device 5, the prefilter 6, and three or more (three in this embodiment) membrane filtration devices 7 connected in parallel to each other ( 7-1, 7-2, 7-3) and a treated water tank 8 for storing treated water to be supplied to the thermal device 2. In the water supply, the upstream side of the reverse osmosis membrane unit 9 is referred to as treated water, and the downstream side of the reverse osmosis membrane unit 9 is referred to as treated water. In the water supply line 3, the upstream side of each reverse osmosis membrane portion 9, which will be described later, included in each membrane filtration device 7 is referred to as a treated water line 3-1, and the downstream side of each reverse osmosis membrane portion 9 is treated water. This is referred to as line 3-2.

  The thermal device 2 is a steam boiler, a hot water boiler, a cooling tower, a water heater, or the like. The activated carbon filtration device 4 is configured as a device for adsorbing and removing an oxidizing agent such as sodium hypochlorite dissolved in the water supply. The soft water device 5 is configured as a device that removes hardness components such as calcium and magnesium contained in the water supply from which the residual chlorine has been removed with an ion exchange resin (not shown). The pre-filter 6 is for removing dust and the like in the water supply.

  Referring to FIG. 2, each membrane filtration device 7 includes a reverse osmosis membrane portion 9, a pump 10 connected to the upstream side of the reverse osmosis membrane portion 9, and an upstream side of each reverse osmosis membrane portion 9. And various detectors 11 (11a to 11e) connected to the downstream side, an inverter (not shown) connected to the pump 10, control of the pump 10, and filtration members of the reverse osmosis membrane portions 9 The first controller 12 is configured to judge clogging and / or deterioration, control the entire apparatus, and control notification means (not shown) that displays the clogging and / or deterioration warning. ing. Hereafter, each said component is demonstrated.

  Each of the reverse osmosis membrane portions 9 includes a nanofiltration membrane (NF membrane, NF: Nanofiltration) as a filtration member.

  Water supplied from the pump 10 flows into one end of each reverse osmosis membrane portion 9. In the supplied water, the corrosion promoting component as a filtration component is captured and the corrosion inhibiting component is permeated by the nanofiltration membrane inside each reverse osmosis membrane portion 9. From the other end of each reverse osmosis membrane section 9, permeated water and concentrated water flow out. The permeated water flows through the treated water line 3-2 as treated water and is stored in the treated water tank 8. On the other hand, a part of the concentrated water flows toward the drainage line 13 and the rest flows through the circulating water line 14 and is supplied to the upstream side of the pump 10.

  The pump 10 is for supplying the reverse osmosis membrane section 9 with water that has been removed from dust and the like flowing through the water to be treated 3-1 on the downstream side of the prefilter 6, and its rotation. The number is configured to vary according to the output frequency output from the inverter.

  The various detectors 11 include a flow sensor 11a, a water temperature sensor 11b, an inlet pressure sensor 11c, an outlet pressure sensor 11d, and an electric conduction sensor 11e. The flow rate sensor 11a detects the amount of permeated water that has passed through each reverse osmosis membrane unit 9 and outputs a flow rate detection signal to the first controller 12. It is connected to the downstream treated water line 3-2.

  The water temperature sensor 11b functions as the water temperature detecting means of the present invention. The treated water line 3-1 on the upstream side of each reverse osmosis membrane unit 9 and the treated water on the downstream side of each reverse osmosis membrane unit 9 Connected to either the line 3-2 or the drainage line 13, and in this first embodiment, the treated water line 3-1 upstream of each reverse osmosis membrane section 9 and upstream of the pump 10. It is connected to the. The water temperature sensor 11 b is configured to detect the temperature of the water supply and output a temperature detection signal to the first controller 12.

  The inlet operating pressure sensor 11c and the outlet back pressure sensor 11d are connected to the treated water line 3-1 and the treated water line 3-2 on the upstream side and the downstream side of the respective reverse osmosis membrane sections 9, respectively. The pressure is detected and a pressure detection signal is output to the first controller 12.

The electric conduction sensor 11e is connected to the treated water line 3-2 on the downstream side of each reverse osmosis membrane section 9 and detects the electric conductivity of the permeated water that has passed through each reverse osmosis membrane section 9 and detects the detected signal. Is output to the first controller 12.

  The flow rate sensor 11a, the inlet operating force sensor 11c, and the water temperature sensor 11b function as the membrane performance detecting means of the present invention that detects the permeation flux.

  The first controller 12 includes a first CPU, first storage means (ROM, RAM), and an interface, and inputs signals from the various detectors 11a to 11e and signals from the second controller 19 described later.

  The first storage means stores a membrane performance detection procedure, a control procedure for controlling the number of operating reverse osmosis membrane sections 9, 9,.

  Referring again to FIG. 1, electromagnetic valves 16 (16-1, 16-2, 16-3) are provided on the downstream side of the membrane filtration devices 7, respectively, and upstream of the treated water tank 8. In the treated water line 3-2 where the treated water of the membrane filtration devices 7 flows and flows, the second electrical conductivity sensor 17 for confirming the water quality and the second flow sensor 18 for confirming the flow rate. The detection signal is input to the second controller 19.

The second controller 19 includes a second CPU, a second storage means (ROM, RAM), and an interface, and is connected to the first controller 12 to control the membrane filtration devices 7. The electromagnetic valve 16 is controlled. Each electromagnetic valve 16 is closed when the reverse osmosis membrane portion 9 needs to be cleaned, when the operation is stopped, or when the operation is on standby.

  The second controller 19 executes the flow rate control procedure shown in FIG. 3 and the priority operation control procedure shown in FIG. 4 stored in the second storage means in cooperation with the first controller 12.

  In the flow rate control procedure, the permeation flux of each reverse osmosis membrane unit 9 is detected to set the operation priority of the reverse osmosis membrane unit 9 and the reverse osmosis according to the water level of the treated water tank 8. This is a control procedure for setting the number of operating membrane units 9 and the treated water flow rate so that the treated water flow rate of each reverse osmosis membrane unit 9 becomes the set flow rate.

  More specifically, the priority of the reverse osmosis membrane portion 9 having a large (high) permeation flux is set high, and the water level of the treated water tank 8 is H or higher, H to M, as shown in FIG. For M to L and below, the number of operating reverse osmosis membrane units 9 is set to 0, 1, 2 and 3 respectively, and the set flow rate of each reverse osmosis membrane unit 9 is the rated flow rate. It is set to 4t / h. The total treated water flow rate in FIG. 5 is the product of the rated flow rate and the number of operating units. Here, the relationship between H, M, and L is H> M, M> L.

  The control procedure for the priority operation is a procedure for preferentially using the reverse osmosis membrane unit 9 having high membrane performance when the increase or decrease in the number of operation units is determined by determining increase or decrease in the number of operation of the reverse osmosis membrane units 9. Yes, more specifically, when it is determined that the number of operating units is increased, the reverse osmosis membrane unit 9 that is not operating is preferentially operated with high membrane performance detected by the membrane performance detecting means, When it is determined that the number of units is reduced, this is a control procedure that preferentially stops the reverse osmosis membrane unit 9 that is in operation and that has a low membrane performance. Specifically, as shown in FIG. 5, the reverse osmosis membrane unit 9 is configured to operate with a higher priority (the smaller the number, the higher the priority).

The second controller 19 determines whether the required water quality Q1 is satisfied based on the detection signal from the second electrical conductivity sensor 17, and the set flow rate is satisfied based on the detection signal from the flow sensor 18. If it is not satisfied, control is also performed to notify the user by the reporting means. This notification includes a notification to inform the user by a buzzer or a display panel (not shown) and a notification to a management device (not shown) by communication. When the required water quality Q1 is not satisfied, it is desirable to perform control to increase the flow rate ratio set so as to satisfy the required water quality Q1.

  The control function of the second controller 19 can be given to each of the first controllers 12. In this case, the second controller 19 can be omitted. The control function of each first controller 12 can be integrated with the second controller 19. In this case, the first controller 12 can be omitted.

Next, the operation of the first embodiment will be described below.
(Overall operation)
The feed water that flows out from the untreated water tank (not shown) first passes through the activated carbon filtration device 4 and becomes the feed water in a state where residual chlorine is removed. Next, the water supply passes through the water softening device 5 and becomes soft water. Subsequently, the soft water (water to be treated) passes through the pre-filter 6 and is filtered in each membrane filtration device 7 to become treated water that can be supplied to the thermal equipment 2. Specifically, when the water to be treated, which is soft water, passes through the nanofiltration membrane in each reverse osmosis membrane section 9 of the membrane filtration device 7, corrosion promoting components such as sulfate ions and chloride ions are added to the nanofiltration membrane. Captured by That is, the corrosion promoting component is removed from the soft water. On the other hand, silica contained in the soft water, that is, the corrosion inhibiting component permeates the nanofiltration membrane together with the soft water. The treated water that becomes soft water containing the corrosion inhibiting component after the filtration treatment is stored in the treated water tank 8 as feed water that can be supplied to the thermal equipment 2.

(Flow control / number control operation of each membrane filtration device 7)
Next, the operation of the first embodiment based on the control procedure of FIGS. 3 and 4 will be described.

  In processing step S1 (hereinafter, processing step SN is simply referred to as SN), the membrane performance is detected, that is, the permeation flux is calculated. The calculation of the permeation flux is performed using Equation 1 and can be performed by a known method. In Example 1, the permeation flux is measured a plurality of times, and the average value is held as the average permeation flux.

  Next, in S2, the priority order of the reverse osmosis membrane unit 9 is set. That is, the higher the average permeation flux, the higher priority is set as priority 1, priority 2, and priority 3. This priority order is set periodically, for example, once / day. The reverse osmosis membrane part 9 from which the permeation flux cannot be obtained has the lowest priority.

  In S3, as shown in FIG. 5, the number of operating units is set according to the water level of the treated water tank 8. When the water level is H or higher, the number of operating units is set to 0. When the water level is H to M, the operating number is set to 1. When the water level is M to L, the operating number is set to 2. Set and set the number of units to 3 when the water level is below L. Although the values for changing the number of operating units are H, M, and L, the number of units is controlled by giving a differential between when the water level rises and when it falls. In S3, the set flow rate of each reverse osmosis membrane unit 9 is set to the rated flow rate.

Next, in S4, priority operation control is performed. In this control, referring to FIG. 4, in S41, the reverse osmosis membrane unit 9 is operated by the number of operation set in S3 from the highest priority. At the beginning of operation, it is determined in S42 that there is no increase / decrease, and thereafter, in S42, it is determined whether the number of units operated in S3 has been changed. If it is determined that the number of operating units is increased, in S44, an operation with a high priority during operation stop, that is, a high average permeation flux of the reverse osmosis membrane unit 9 is operated. If it is determined that the number of operating units is reduced, the operation with low priority during operation, that is, the one with the low average permeation flux of the reverse osmosis membrane unit 9 is stopped in S43. The operation / stop of the reverse osmosis membrane unit 9 is performed by operating / stopping the pump 10 connected to the reverse osmosis membrane unit 9 and opening / closing the electromagnetic valve 16.

  Next, returning to FIG. 3, in S5, the rotational speed of the pump 9 to be operated is controlled so that the flow rate detected by the flow rate sensor 11a becomes the set flow rate. That is, in each reverse osmosis membrane part 9 with low membrane performance, the rotational speed of the pump 9 is controlled to be high, and in each reverse osmosis membrane part 9 with high membrane performance, the rotation of the pump 9 is controlled. The number will be controlled low.

  As described above, in the first embodiment, the reverse osmosis membrane unit 9 having high membrane performance is prioritized when the number of operating reverse osmosis membrane units 9 is controlled according to the water level of the treated water tank 8. Therefore, the rotational speed of the pump 9 of each reverse osmosis membrane section 9 is controlled to be low as a whole. As a result, the power consumption of the pump 10 can be reduced and energy saving can be realized.

  Further, according to the first embodiment, the reverse osmosis membrane portion 9 having high membrane performance is operated with priority, so that the deterioration of the membrane performance of each reverse osmosis membrane portion 9 can be made uniform. Play. As a result, in the first embodiment, when the membrane cleaning and the membrane exchange of all the reverse osmosis membrane portions 9 are performed at the same time, the membrane cleaning and the membrane exchange are performed with the most ability of the membrane being used. As a result, it is possible to increase the interval between membrane cleaning and membrane exchange.

  In the first embodiment, the processing steps S1 to S3 can be included in the processing step S4.

  The present invention is not limited to the first embodiment, and may be a second embodiment shown in FIGS. The second embodiment will be described below with a focus on the differences from the first embodiment. The same constituent elements as those in the first embodiment and the processing steps of the control procedure are denoted by the same reference numerals and description thereof is omitted. FIG. 6 is a flowchart for explaining the control procedure of the second embodiment. FIG. 7 is a schematic configuration diagram of each membrane filtration device of the second embodiment, FIG. 8 is a diagram for explaining the relationship of the required maintenance flow rate with respect to operation priority, and FIG. 9 is a diagram with respect to the water level of the treated water tank. It is a figure explaining the relationship of an operation pattern. FIG. 10 is a characteristic diagram of the permeation ratio with the flow rate ratio and the water temperature of the second embodiment as parameters, and FIG. 11 is a water quality characteristic diagram of the second embodiment with the flow rate ratio and the water temperature as parameters. These are effective operation pressure characteristic diagrams using the flow rate ratio and water temperature of the second embodiment as parameters, and FIG. 13 is an energy saving ratio characteristic diagram of the flow rate ratio and water temperature of the second embodiment as parameters.

  This Example 2 does not use the set value of the treated water flow rate of each reverse osmosis membrane section 9 as the rated flow rate as in Example 1, but the minimum flow rate that maintains the required water quality Q1 of the thermal device 2. This is different from the first embodiment in that the required water quality maintenance flow rate R1 is set.

  The first storage means stores a membrane performance detection procedure, a control procedure for obtaining the required water quality maintenance flow rate R1, and the like.

  The first storage means stores in advance the relational characteristics of the treated water flow rate ratio, the water temperature of each reverse osmosis membrane part 9 and the treated water quality of each reverse osmosis membrane part. These are the water quality characteristics of the treated water using the flow rate ratio and water temperature of each reverse osmosis membrane part as parameters. This water quality characteristic is for obtaining the required water quality maintenance flow rate R1, which is the lower limit treated water flow rate for maintaining the required water quality Q1 of the thermal device 2 with respect to the treated water.

In the second embodiment, the water quality characteristics are stored in a table format as shown in FIG. And this water quality characteristic is calculated | required as follows. First, as shown in FIG. 10, the ion permeation ratio is obtained using the flow rate ratio and the water temperature as parameters. The flow rate ratio-water temperature characteristic of the ion permeation ratio is expressed by a correction coefficient K (K11 to K65, where K63 = 1.000). As an example, the value of water quality (mg / L) at a water temperature of 25 ° C. and a flow rate ratio of 100% is 10.9 (when the quality of the water to be treated and the recovery rate are constant), and this value is multiplied by the correction coefficient K. Thus, as shown in FIG. 11, the water quality (mg / L) using the flow rate ratio of the treated water and the water temperature as parameters is obtained. This is stored in the storage means as water quality characteristics.

  Below, this water quality characteristic is demonstrated. When the treated water quality is expressed in terms of ion removal rate% (the amount of treated water divided by the amount of ions removed by the reverse osmosis membrane), the ion removal rate is the flow rate ratio when the water temperature is constant. As the water temperature rises, it increases (water quality improves), and when the flow rate ratio is constant, it shows a tendency to decrease (water quality decreases) as the water temperature rises.

  In the water quality characteristics, the treated water quality can be expressed by ion permeability% (a value obtained by dividing the amount of ions of the water to be treated divided by the amount of ions permeated through the reverse osmosis membrane). When the water temperature is constant, the ion permeability decreases as the flow rate increases (water quality improves), and when the flow rate is constant, the ion permeability shows a tendency to increase (water quality decreases) as the water temperature increases. .

  Further, the quality of treated water can be expressed by an ion transmission ratio. This ion permeation ratio is a value obtained by dividing the ion permeation rate when the flow rate ratio and the water temperature are changed by the ion permeation rate at a specific flow rate ratio and a specific water temperature. The change in the value of the ion permeation ratio with respect to the increase and decrease in the flow rate ratio and the water temperature changes with the same tendency as the ion permeation rate.

  Furthermore, the quality of treated water can be directly expressed by water quality (mg / L) and can be detected by electric conductivity (mS / m). Water quality (mg / L) shows the same tendency as ion permeability and ion permeability ratio. That is, water quality (mg / L) decreases as the flow rate ratio increases (water quality improves) when the water temperature is constant, and increases as the water temperature increases (water quality decreases) when the flow rate ratio is constant. Show a tendency to

  The ion removal rate and the ion transmission rate are preferably obtained in real time, but in the first embodiment, the ion transmission rate is calculated from data at the time of a trial run or the like and is input to the first storage means, and this is set under certain conditions. The initial ion permeability under the water temperature (for example, a water temperature of 25 ° C.) is used. The ion permeability ratio is obtained from the ion permeability thus obtained, and the water quality (mg / L) characteristics of the treated water from the ion permeability ratio and the water quality (mg / L) measured at a specific flow rate ratio and a specific water temperature. Ask for.

Since the “flow rate ratio” in this water quality characteristic is equivalent to the treated water flow rate and has a predetermined relationship with the operating pressure, it can be expressed by replacing the “flow rate ratio” with the treated water flow rate or the operating pressure. In addition, since “water quality (mg / L)” has a predetermined relationship with the ion removal rate, ion transmission rate, and ion transmission rate, “water quality (mg / L)” is the ion removal rate, ion transmission rate, and ion transmission rate. It can be expressed as any of the ratios. Accordingly, in the present invention, “flow rate ratio” includes treated water flow rate and operating pressure, and “water quality (mg / L)” is a concept including electrical conductivity, ion removal rate, ion permeability, and ion permeability ratio. . In short, the water quality characteristic is not particularly limited as long as the flow rate of the treated water can be directly or indirectly determined from the predetermined treated water quality.

  The second controller 19 executes a flow rate / water quality control procedure for controlling the flow rate and water quality shown in FIG. 6 stored in the second storage means in cooperation with the first controller 12.

The flow rate / water quality control procedure controls the number of operating reverse osmosis membrane sections 9 according to the water level of the treated water tank 8, and rotates the pumps so that the treated water quality becomes the required water quality maintenance flow rate R1. It is a procedure to control the number. More specifically, the priority of the reverse osmosis membrane section 9 having a large permeation flux is set high, and the water level of the treated water tank 8 is H or higher, as shown in FIG. 9, H to M2, M2 to M1. , M1 to L, L or less, the number of operating the reverse osmosis membrane units 9 is set to 0, 1, 2, 3, and 3, respectively. When the water level is H to M2, M2 to M1, and M1 to L, the set flow rate of each reverse osmosis membrane unit 9 is set to the required water quality maintenance flow rate R1. To control.

Next, the operation of the second embodiment will be described below.
(Flow control operation of each membrane filtration device 7)
The operation of the second embodiment based on the control procedure of FIG. 6 will be described. In the following description, it is assumed that the quality of the water to be treated is constant.

  First, in S21, as the membrane performance, in addition to the permeation flux, the ion permeability is detected. As shown in FIG. 7, the ion permeability is obtained by subtracting the detection value of the electrical conductivity sensor 11e on the outlet side from the detection value of the electrical conductivity sensor 11f provided on the inlet side of each reverse osmosis membrane portion 9. By dividing by the detection value of the electrical conductivity sensor 11f, the ion removal rate is obtained, and the ion transmission rate is calculated by (100−ion removal rate). Since the processing step S2 is the same as that of the first embodiment, the description thereof is omitted.

  In S6, the required water quality Q1 of the thermal device 2 stored in the second storage unit in advance is read (determined). In S7, the water temperature T0 is detected by the water temperature sensor 11a.

Next, in S81, the relationship between the operation priority order and the required water quality maintenance flow rate as shown in FIG. 8 is set from the water temperature and membrane performance of the water to be treated. That is, first, the required water quality maintenance flow rate R1 of each reverse osmosis membrane section 9 is obtained as follows. The water quality characteristic as shown in FIG. 11 stored in the first storage means is read out, and the ion permeability detected in S1 for this water quality characteristic is used as the initial ion permeability of each reverse osmosis membrane section 9 (at the time of product shipment). Correction by the deterioration correction coefficient Y based on the deterioration of the film divided by the value of the ion transmission rate of the film. Specifically, the water quality characteristic is corrected by multiplying the water quality value in FIG. 11 by Y. That is, the corrected water quality characteristic is obtained by 10.9 × K (ion transmission ratio) × Y.

  Next, based on the required water quality Q1 determined in S6 and the detected water temperature T0 obtained in S7, the required water quality Q1 is calculated from the water quality characteristics corrected based on the ion permeability detected for each reverse osmosis membrane section 9. The required water quality maintenance flow rate R1, which is the minimum flow rate to be satisfied, is calculated. Specifically, it is assumed that the water quality characteristic of the filtration membrane device 7-1 is now expressed in FIG. 11, Y = 1, the required water quality Q1 is Q23, and the detected water temperature is 25 ° C. Then, the flow rate ratio at which the water quality is Q23 is obtained from the 25 ° C. column in the table of FIG. That is, when the required water quality is Q23, the flow rate ratio is 60%. When the value of the required water quality Q1 is not in the table, for example, between Q23 and Q33, it is obtained by proportional distribution between the flow rate ratios of 60% and 70%. That is, it can be obtained by 60% + 10% × (Q23−Q1) / (Q23−Q33).

  Further, when the membrane performance (permeation flux) of the filtration membrane devices 7-2 and 7-3 is lowered and the water quality characteristics satisfy the required water quality Q1 at flow rate ratios of 70% and 80%, respectively, As shown in FIG. 8, the operation priorities of the filtration membrane devices 7-1, 7-2, 7-3 are set to priorities 1, 2, 3, respectively, and the flow rate ratios are 60%, 70%, 80%. Set to.

Then, in S 81 , as shown in FIG. 9, the filtration membrane device 7-1 is stopped, the flow rate control operation (flow rate ratio 60%), the rating according to the water level of the treated water tank 8 and the operation priority. The operation is set to any one of the operation patterns, the filtration membrane device 7-2 is stopped, the flow control operation (flow rate ratio 70%), or the operation operation is set to any one of the rated operation, and the filtration membrane device 7-3 is set. Is set to one of the operation patterns of stop, flow control operation (flow rate ratio 80%), or rated operation. Since the process of S3 is the same as that of the said Example 1, the description is abbreviate | omitted. Moreover, since the process of S4 is the same as that of the said Example 1, the description is abbreviate | omitted.

  In S5, the flow rate detected by each flow sensor 11a in each reverse osmosis membrane section 9 is the set flow rate of the operation pattern set in S8 (flow rate ratio 60%, flow rate ratio 70%, flow rate ratio 80%, rated flow rate). The number of rotations of the pump 9 connected to each reverse osmosis membrane section 9 is controlled so that

  As described above, in this second embodiment, as in the first embodiment, the membrane performance is high when controlling the number of operating reverse osmosis membrane sections 9 according to the water level of the treated water tank 8. Since the reverse osmosis membrane unit 9 is operated with priority, the rotational speed of the pump 9 of each reverse osmosis membrane unit 9 is controlled to be low overall. In addition, when the water level is H to M2, M2 to M1, and M1 to L, the required water quality maintenance flow rate corresponding to the change in membrane performance of each reverse osmosis membrane portion is set as the set treatment water flow rate of each reverse osmosis membrane portion 9. Since it is set to R1, the rotation speed of the pump 9 of each said reverse osmosis membrane part 9 is generally controlled low so that a treated water quality may not become an excessive water quality. As a result, the power consumption of the pump 10 can be reduced and energy saving can be realized.

Here, the reason why energy saving is realized by operating each pump 10 at a low rotational speed so that the treated water flow rate becomes low will be described. Now, when the permeation flux is 40 (L / m ² · h · MPa) and the rated flow rate is 4000 (L / h), the flow rate ratio (treated water flow rate) of the reverse osmosis membrane section 9 and the water temperature are The operating pressure characteristics as parameters are, for example, characteristics as shown in FIG. This characteristic shows that when the water temperature is constant, the operating pressure required to obtain the treated water flow rate increases as the flow rate ratio increases.

On the other hand, the power consumption of the pump is proportional to the 1.5th power of the operating pressure. That is, the energy saving ratio = (W2 / W1) ∝ (P2 / P1) ^1.5 . If the operating pressure characteristics are as shown in FIG. 12, the energy saving ratio is as shown in FIG. Therefore, when the flow rate ratio that satisfies the required water quality Q1 = Q33 is 70%, the pump power consumption ratio is 100/70 (time ratio) × 0.586 (pump power consumption ratio) = 0.837. 16.3% power saving. Similarly, 60% operation results in 22.5% power saving, and 50% operation results in 29.2% power saving.

  Also in the second embodiment, as in the first embodiment, since the reverse osmosis membrane portion 9 having high membrane performance is preferentially operated, the membrane performance of each reverse osmosis membrane portion 9 is improved. There is an effect that the deterioration can be made uniform.

Moreover, this invention can be made into Example 3 which performs the process sequence of FIG. 14, FIG. Hereinafter, the third embodiment will be described with a focus on differences from the first and second embodiments. The same components as those in the first and second embodiments and the processing steps of the control procedure are denoted by the same reference numerals and description thereof is omitted. 14 and 15 are flowcharts for explaining the control procedure of the third embodiment, and FIG. 16 is a diagram for explaining the relationship of the operation pattern with respect to the water level of the treated water tank.

In this third embodiment, as in the second embodiment, the number of the reverse osmosis membrane units 9 to be operated is not determined only by the water level of the treated water tank 8, and the treated water flow rate of each reverse osmosis membrane unit 9 is determined. Is not the rated flow rate or the required water quality maintenance flow rate R1. The third embodiment is different from the first and second embodiments in that the number of the reverse osmosis membrane portions 9 and the number of rotations of the pumps are controlled so that the treated water flow rate and the treated water quality are within a predetermined range.

  The second controller 19 executes the flow rate / water quality control procedure for controlling the flow rate and water quality shown in FIGS. 14 and 15 stored in the second storage means in cooperation with the first controller 12. To do.

  The flow rate / water quality control procedure is a control procedure for controlling the number of the reverse osmosis membrane units 9 and the number of rotations of the pumps so that the treated water flow rate and the treated water quality are within a predetermined range. More specifically, in the flow rate / water quality control procedure, with respect to the treated water flow rate, the value is equal to or greater than the total required water amount R0 from the thermal device 2, and the treated water quality by each reverse osmosis membrane unit 9 is: The control is performed so that the value is equal to or higher than the required water quality Q1 and as close to the required water quality Q1 as possible so as not to become an excessive water quality.

  Now, the relationship between the operation priority of each of the filtration membrane devices 7-1, 7-2, 7-3 and the flow rate ratio satisfying the required water quality Q1 is the same as in FIG. The relationship with the required water amount is shown in FIG.

(Flow control operation of each membrane filtration device 7)
Next, the operation of the third embodiment based on the control procedure of FIGS. 14 and 15 will be described. In the following description, it is assumed that the quality of the water to be treated is constant.

  Referring to FIG. 14, S21, S2, S6, S7, and S81 are the same as those in the second embodiment, and hence the description thereof is omitted.

  In S9, the total required water amount R0 is set according to the water level of the treated water tank 8, and the priority control operation of S10 shown in FIG. 15 is performed.

  Referring to FIG. 15, in S <b> 11, it is determined whether the amount of supplied water (the sum of the flow rates of treated water flowing through the filtration membrane devices 7) ≧ total required water amount. Now, it is assumed that the initial water level of the treated water tank 8 is L or less, and that the filtration membrane devices 7 are rated. When the water level of the treated water tank 8 rises and the water level exceeds L, the total required water amount becomes 8 t / h, and the process proceeds to S12. In S12, the presence / absence of the reverse osmosis membrane portion 9 during rated operation is determined. In this case, YES is determined, and in S13, the supply flow rate ≧ total required water amount when the reverse osmosis membrane portion 9-3 having the lowest priority during the rated operation is set to the flow rate control operation of FIG. 8 is determined. . In this case, YES is determined when 11.2 t / h ≧ 10 t / h, and the process proceeds to S14, and first, the reverse osmosis membrane section 9-3 having the lowest operation priority is subjected to flow control operation (flow rate ratio 80%). And

  Next, the reverse osmosis membrane portion 9-2 with the operation priority 2 is set to a flow control operation (flow rate ratio 70%) by the processing of S11, S12, S13, S14, and the reverse osmosis membrane portion 9- with the operation priority 1 is set. 1 is a flow control operation (flow rate ratio 60%). Thus, when the water level of the treated water tank 8 is between M (> L) and L, as shown in FIG. 16, all three of the reverse osmosis membrane sections 9 are set to flow control operation.

  Next, when the water level of the treated water tank 8 rises and the water level exceeds M, the total required water amount becomes 4 t / h. Therefore, NO is determined in the processing of S12, and priority is given during the flow control operation in S15. When the operation of the reverse osmosis membrane portion 9-3 having the lowest degree is stopped, supply flow rate ≧ total required water amount is determined. In this case, YES is determined at 5.2 t / h ≧ 4 t / h, the process proceeds to S16, and the reverse osmosis membrane portion 9-3 is stopped as shown in FIG. Thus, when the water level of the treated water tank 8 is between H (> M) and M, the reverse osmosis membrane portions 9-1 and 9-2 are set to flow control operation as shown in FIG.

  Further, when the water level of the treated water tank 8 rises and the water level exceeds H, the total required water amount becomes 0 t / h. Therefore, the reverse osmosis membrane portion having the operation priority 2 is obtained by the processing of S12, S15, and S16. 9-2 is stopped, and then the reverse osmosis membrane portion 9-1 having the operation priority 1 is stopped. Thus, while the water level of the treated water tank 8 is higher than H, the operations of the reverse osmosis membrane portions 9-1, 9-2, 9-3 are stopped as shown in FIG.

  Conversely, when the water level in the treated water tank 8 falls below H, NO is determined in S11, and YES is determined in S17. In S18, the reverse osmosis membrane unit 9-1 having the operation priority level 1 during operation stop is operated by the flow rate control operation (flow rate ratio 60%), and the operation priority level 2 is obtained by the processing of S11, S17, and S18. The reverse osmosis membrane portion 9-2 is operated in a flow rate control operation (flow rate ratio 60%). Thus, while the water level of the treated water tank 8 is between H and M, as shown in FIG.

  Similarly, as the water level falls and between M and L, as shown in FIG. 16, all three of the reverse osmosis membrane sections 9 are set to flow control operation. Further, when the water level is equal to or lower than L, NO is determined in S17, and in S19, the reverse osmosis membrane unit 9 having the operation priority 1 is operated in the flow control operation. And the said reverse osmosis membrane part 9-2, 9-3 is rated-operated sequentially by the process of S11, S17, S19. Thus, when the water level is L or less, all reverse osmosis membrane portions 9 are rated.

  As described above, in Example 3, each reverse osmosis membrane section 9 is operated at a required water quality maintenance flow rate that satisfies the required water quality Q1, and the reverse osmosis is performed so that the supplied water amount is equal to or higher than the required water amount. Control of the number of operating membrane portions 9 and rotation speed control of the pump 10 are performed. And when controlling the number of operating units, the reverse osmosis membrane part 9 having high membrane performance is preferentially operated, so the system performance is optimized with respect to the filtered water quality, and the membrane of each reverse osmosis membrane part The clogging and deterioration of can be made uniform. Further, the pump 10 can be operated at a small flow rate and a low rotational speed. As a result, power consumption of the pump 10 of the entire system can be reduced, and energy saving can be realized.

  As a modification of the third embodiment, as shown in FIG. 17, the water level of the treated water tank can be further subdivided to set the total required water amount with respect to the tank water level. In this case, when each said reverse osmosis membrane part 9-1, 9-2, 9-3 is set as the operation priority order 1, 2, 3, respectively, and the required maintenance water amount is set to flow rate ratio 60%, 70%, 80% The operation pattern and the amount of supplied water at each water level are controlled as shown in FIG. 17 according to the control procedure of FIGS. In FIG. 17, α = (HL) / 5.

  The present invention is not limited to the first to third embodiments, but includes the fourth embodiment shown in FIG. This Example 4 is connected in parallel to each other, and is provided in common with a plurality of reverse osmosis membrane portions 9 (9-1, 9-2, 9-3) having the same rated capacity and the respective reverse osmosis membrane portions 9. A water quality reforming system comprising a pump 10 capable of controlling the number of rotations for supplying treated water to each reverse osmosis membrane section. Hereinafter, in this Example 4, it demonstrates centering on a different part from the said Examples 1-3, the same part attaches | subjects the same code | symbol and abbreviate | omits description.

  The difference from the first to third embodiments is that each membrane filtration device 7 (7-1, 7-2, 7-3) is not equipped with a pump, and each membrane filtration device 7 (7-1, 7-2, The common pump 10 is provided in 7-3).

In the fourth embodiment, similarly to the third embodiment, the number of operating units and the number of revolutions of the pump 10 are controlled so that the treated water flow rate and the treated water quality are within a predetermined range. And when performing the unit control, the reverse osmosis membrane part 9 having high membrane performance is preferentially used (operating one having high membrane performance or stopping one having low membrane performance). . As the required water quality maintenance flow rate R1, the largest value in the reverse osmosis membrane portion 9 is adopted.

  The present invention is not limited to the first to fourth embodiments, but includes the fifth embodiment shown in FIG. Hereinafter, in this Example 5, it demonstrates centering on a different part from the said Examples 1-4, the same part attaches | subjects the same code | symbol and abbreviate | omits description. In FIG. 19, signal lines to the controller 19 of each deaeration membrane section 22 and each dissolved oxygen concentration sensor 24 described later are omitted.

  The fifth embodiment includes a plurality of reverse osmosis membrane portions 9 (9-1, 9-2, 9-3) connected in parallel to each other to remove impurities in the water to be treated and supply the devices, and the reverse osmosis units. A pump 10 (10-1, 10-2, 10-3) that is provided for each membrane unit 9 and supplies treated water to the reverse osmosis membrane unit 9 is connected to the downstream side of the reverse osmosis membrane unit 9. A membrane deaerator 20 and a third controller 21 are provided. The membrane deaerator 20 is configured by connecting a plurality of deaerator parts 22 (22-1, 22-2, 22-3) in parallel. Each deaeration membrane part 22 has a well-known configuration, and water to be treated flows on one side of a deaeration membrane (not shown) formed of a hollow fiber membrane or the like, and a vacuum pump (not shown) on the other side. The dissolved gas in the water to be treated is removed by evacuating with a vacuum. An electromagnetic valve 23 (23-1, 23-2, 23-3) for controlling the flow of water supplied to each degassing membrane section 22 is provided on the upstream side of each degassing membrane section 22 in the water supply line 3. ing.

And the film | membrane performance of each said deaeration film | membrane part 22 is detected by the dissolved acid concentration sensor 24 (24-1, 24-2, 24-3) which detects the dissolved oxygen concentration of the downstream of each said deaeration film | membrane part 22. The film performance detecting means is provided. In addition to the function of the second controller 19, the third controller 21 determines the film performance of each degassing membrane section 22 based on a signal from the membrane performance detecting means, and the degassing membrane When it is determined that the number of operating units 22 is increased or decreased, the degassing membrane unit 22 having high membrane performance is used preferentially (operating one having high membrane performance or stopping one having low membrane performance) doing. The operating number of the degassing membrane units 22 is controlled according to the amount of treated water flowing through the membrane degassing device 20, and the operating number is controlled by opening and closing the electromagnetic valve 23. When closing the electromagnetic valve 23, the vacuum pump is stopped.

  Other configurations of the fifth embodiment are the same as those of the first embodiment, but may be the same as those of the second to fourth embodiments.

  According to the fifth embodiment, the system performance can be optimized with respect to the water quality, and the clogging and deterioration of each reverse osmosis membrane section 9 can be made uniform. In addition, since the reverse osmosis membrane unit 9 having high membrane performance is operated with priority, the rotation speed of the pump is used to obtain a predetermined treated water flow rate and / or treated water quality in each reverse osmosis membrane unit 9 to be operated. The power consumption of the pump 10 can be reduced.

  In addition, since the degassing membrane part 22 having high membrane performance is operated with priority, the system performance can be optimized with respect to deaerated water quality, and the clogging and deterioration of each deaeration membrane part 22 can be made uniform. There is an effect.

It goes without saying that the present invention can be variously modified without departing from the spirit of the present invention. That is, the control of the treated water supply amount and the treated water quality is not limited to FIGS. 14 and 15 and can be variously changed. For example, as described in Patent Document 2 (Japanese Patent Laid-Open No. 2001-239134), reverse osmosis treatment is performed by boosting water to be treated and supplying the water to a plurality of reverse osmosis membrane parts connected in parallel to obtain water to be treated. When the apparatus is operated, the number of the reverse osmosis membrane units can be controlled according to the temperature of the water to be treated and / or the quality of the water to be treated. Specifically, this control controls the supply pressure of the water to be treated according to the temperature change of the water to be treated so that the flow rate and quality of the water to be treated are within a predetermined range, and the reverse osmosis membrane The number of operating units is controlled.

  In the first to fourth embodiments, the following configuration can be added as described in JP-A-2008-658. The structure includes a reverse osmosis membrane part that removes impurities in the feed water, drains a part of the concentrated water from the reverse osmosis membrane part, and recirculates the remaining part to the upstream side of the reverse osmosis membrane part. And a control means for controlling the reflux amount adjusting means according to the drainage amount of the concentrated water from the reverse osmosis membrane portion or the permeated water amount from the reverse osmosis membrane portion. Are provided.

  By adding such a configuration, the ratio of the concentrated water amount to the permeated water amount can be maintained when the pump is controlled at the predetermined flow rate. As a result, it is possible to prevent wasted power from being consumed in the pump for supplying water to the reverse osmosis membrane part, and the flow rate at the surface of the filtration membrane of the reverse osmosis membrane part is maintained and The filter membrane can be prevented from being clogged by the ring.

  In the second to fourth embodiments, as in the first embodiment, the second controller 19 determines whether the required water quality Q1 is satisfied by the detection signal of the second electrical conductivity sensor 17. A determination is made based on a detection signal from the flow sensor 18 to determine whether or not the set flow rate is satisfied. If the set flow rate is not satisfied, control is performed to notify the user by the notification means. This notification includes a notification to inform the user by a buzzer or a display panel (not shown) and a notification to a management device (not shown) by communication. When the required water quality Q1 is not satisfied, it is desirable to perform control to increase the flow rate ratio set so as to satisfy the required water quality Q1.

  Furthermore, the present invention can also be applied to a water quality reforming system that includes only the membrane deaerator 20 in the fifth embodiment but does not include the filtration membrane device 7.

DESCRIPTION OF SYMBOLS 1 Water quality reforming system 2 Thermal equipment 3 Water supply line 7 Membrane filtration device 8 Treated water tank 9 Reverse osmosis membrane section 10 Pump 11a Flow rate sensor 11b Water temperature sensor 11c Inlet pressure sensor 11d Outlet back pressure sensor 11e Electrical conduction sensor 11f Electrical conduction sensor 12 First controller

Claims (4)

A plurality of separation membrane parts connected in parallel to each other to remove the impurities in the treated water and supply the treated water to the device, and a rotation for supplying the treated water to each separation membrane part provided for each of the separation membrane parts A water quality reforming system comprising a number-controllable pump and a control means for controlling the number of operating separation membrane units and individually controlling the number of rotations of each pump;
Water temperature detecting means for detecting the water temperature;
First membrane performance detecting means for detecting the membrane performance of each separation membrane part by permeation flux;
A second membrane performance detecting means for detecting the membrane performance of each separation membrane portion by a reference ion permeability at a reference water temperature and a reference rated flow rate ;
A required water quality determination means for determining a required water quality of the equipment for treated water;
A flow rate detection means for detecting the flow rate of the treated water in each separation membrane part;
A water quality characteristic table of treated water quality using the treated water flow rate and water temperature of each separation membrane as parameters, and storage means for storing in advance the initial reference ion permeability at the reference water temperature and the reference rated flow rate ,
The control means, based on said flux by the first membrane performance detection means, wherein the step of setting the priority of the separation membrane, the value of the detection standard ion transmission by the second membrane performance detecting means initial A step of obtaining a deterioration correction coefficient by dividing by a value of the reference ion transmittance, multiplying the value of the treated water quality of the water quality characteristic table by the deterioration correction coefficient to correct each water quality characteristic table, and the water temperature detecting means Based on the water temperature by the required water quality and the required water quality by the required water quality judging means, the required water quality maintenance flow rate that obtains the treated water quality that satisfies the required water quality is calculated from each water quality characteristic table corrected for each separation membrane section. The step of setting the relationship between the rank and the required water quality maintenance flow rate, the step of determining the increase / decrease in the number of operation of the separation membrane unit, and the priority order when determining the increase or decrease in the number of operation A step of giving priority to the separation membrane having a high priority and stopping the separation membrane having a low priority during operation, and a detection flow rate of the flow rate detecting means in the separation membrane in operation And a step of controlling the rotational speed of the pump so that the required water quality maintenance flow rate is achieved. A plurality of separation membrane parts connected in parallel to each other to remove the impurities in the treated water and supply the treated water to the device, and a rotation for supplying the treated water to each separation membrane part provided for each of the separation membrane parts A number-controllable pump, a membrane deaerator connected to the downstream side of the separation membrane unit, and a control means for controlling the number of operation of the separation membrane unit and individually controlling the number of rotations of each pump; A water quality reforming system comprising:
Water temperature detecting means for detecting the water temperature;
First membrane performance detecting means for detecting the membrane performance of each separation membrane part by permeation flux;
A second membrane performance detecting means for detecting the membrane performance of each separation membrane portion by a reference ion permeability at a reference water temperature and a reference rated flow rate ;
A required water quality determination means for determining a required water quality of the equipment for treated water;
A flow rate detection means for detecting the flow rate of the treated water in each separation membrane part;
A water quality characteristic table of treated water quality using the treated water flow rate and water temperature of each separation membrane as parameters, and storage means for storing in advance the initial reference ion permeability at the reference water temperature and the reference rated flow rate ,
The control means, based on said flux by the first membrane performance detection means, wherein the step of setting the priority of the separation membrane, the value of the detection standard ion transmission by the second membrane performance detecting means initial A step of obtaining a deterioration correction coefficient by dividing by a value of the reference ion transmittance, multiplying the value of the treated water quality of the water quality characteristic table by the deterioration correction coefficient to correct each water quality characteristic table, and the water temperature detecting means Based on the water temperature by the required water quality and the required water quality by the required water quality judging means, the required water quality maintenance flow rate that obtains the treated water quality that satisfies the required water quality is calculated from each water quality characteristic table corrected for each separation membrane section. The step of setting the relationship between the rank and the required water quality maintenance flow rate, the step of determining the increase / decrease in the number of operation of the separation membrane unit, and the priority order when determining the increase or decrease in the number of operation A step of giving priority to the separation membrane having a high priority and stopping the separation membrane having a low priority during operation, and a detection flow rate of the flow rate detecting means in the separation membrane in operation And a step of controlling the rotational speed of the pump so that the required water quality maintenance flow rate is achieved. The membrane deaerator is composed of a plurality of deaeration membrane parts connected in parallel with each other,
A valve for controlling the flow of treated water is provided in the water supply line of each deaeration membrane part,
Third membrane performance detection means for detecting the membrane performance of each deaeration membrane part based on the dissolved oxygen concentration downstream of each deaeration membrane part,
The control means determines the film performance of the deaeration membrane part based on the dissolved oxygen concentration by the third membrane performance detection means, determines the increase / decrease in the number of operating units of the deaeration film part, When it is determined that the number of units is increased or decreased, the step of giving priority to the deaeration membrane unit having a high membrane performance and / or the step of giving priority to stopping the deaeration membrane unit having a low membrane performance are performed. The water quality reforming system according to claim 2. A plurality of separation membrane parts connected in parallel to each other to remove the impurities in the treated water and supply the treated water to the device, and a rotation for supplying the treated water to each separation membrane part provided for each of the separation membrane parts A number of controllable pumps, individually controlling the number of rotations of each pump, and controlling the number of operating separation membrane units,
A water quality characteristic table of treated water quality using the treated water flow rate and water temperature of each separation membrane section as parameters, and an initial reference ion permeability at a reference water temperature and a standard rated flow rate are stored in advance.
Detecting the membrane performance of each of the separation membrane portions by a permeation flux , and a reference ion permeability at a reference water temperature and a reference rated flow rate;
Setting the priority of the separation membrane unit based on the detected permeation flux;
The value of the detection reference ion permeability by dividing the value of the initial reference ion permeability calculated deterioration correction factor, by multiplying the deterioration correction coefficient to the value of the treated water quality of the water quality characteristic table, wherein each quality characteristic table A step of correcting
Determining the required water quality of the equipment for treated water;
Detecting the water temperature;
Based on the detected water temperature and the determined required water quality, the required water quality maintenance flow rate for obtaining the treated water quality satisfying the required water quality is calculated from each water quality characteristic table corrected for each separation membrane unit, and the priority order is calculated. And setting a relationship between the required water quality maintenance flow rate,
Determining an increase / decrease in the number of operating separation membrane units;
When it is determined that the number of operating units is increased or decreased, priority is given to the separation membrane unit having a high priority and the operation and / or the separation membrane unit having a low priority during operation is stopped.
And a step of controlling the number of revolutions of the pump so that the detected flow rate of the flow rate detection means becomes the required water quality maintenance flow rate in the separation membrane section in operation.

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