JP2010131579A - System for improving water quality - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily achieve energy saving by reducing power consumption of a pump while maintaining the water quality of treated water regardless of change of water temperature and the like. <P>SOLUTION: A system for improving water quality comprises a reverse osmosis membrane portion 9, a pump 10 for supplying water to be treated to the reverse osmosis membrane portion 9, and a control means for controlling the number of revolutions of the pump 10. The system includes at least a water temperature sensor 11e for detecting water temperature, a required water quality determining means for determining the required water quality of an apparatus 2, and a flow rate sensor 11a for detecting the flow rate of treated water. The control means 12 performs a first step for setting mutual relational characteristics among the flow rate of the treated water, water temperature, and the water quality of the treated water, a second step for calculating a predetermined flow rate satisfying the required water quality from the relational characteristics based on the water temperature detected by the water temperature sensor 11e and the required water quality determined by the required water quality determining means, and a third step for controlling the number of revolutions of the pump 10 so that the flow rate detected by the flow rate sensor 11a may becomes the predetermined flow rate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In this type of water quality reforming system, the reverse osmosis membrane changes in water viscosity and membrane characteristics depending on the water temperature, so the filtration flow rate changes greatly. In order to solve this problem, the applicant has proposed the following system in Patent Document 1. This water quality reforming system is a water quality reforming system for reforming the quality of water supplied to equipment, a reverse osmosis membrane part for removing impurities in the feed water, and a pump for supplying feed water to the reverse osmosis membrane part. A flow rate sensor for detecting the flow rate of the permeated water from the reverse osmosis membrane part, an inverter for changing the rotational speed of the pump according to an output frequency, and a flow rate detection signal from the flow rate sensor to the inverter. And a control unit that outputs a command signal.

  In this water quality reforming system, the target rotational speed of the pump to be controlled is generally set to the required flow rate of the treated water (required treated water flow rate) by the equipment, so that the quality of the treated water is Excessive water quality exceeding the required water quality of the equipment. That is, this conventional water quality reforming system is a control with priority on the required flow rate, and without considering the required treated water flow rate, up to the control for further energy saving operation of the pump while satisfying the required water quality, Not specifically mentioned.

JP 2005-296945 A

  As a result of studying the usage pattern of the system, the inventors of this application pay attention to the fact that there is a usage pattern that can operate the system without considering the treated water flow rate of the equipment, and actively use such usage pattern. Accordingly, it is an object of the present invention to reduce the power consumption of the pump while maintaining the quality of the treated water regardless of changes in the water temperature or the like, and to easily realize energy saving.

  This invention was made in order to solve the said subject, The invention of Claim 1 removes the impurity in to-be-processed water, the reverse osmosis membrane part which supplies treated water to an apparatus, and to-be-processed water Is a water quality reforming system comprising a pump for supplying water to the reverse osmosis membrane part, and a control means for controlling the rotation speed of the pump, and detects a value of a change factor of the treated water quality of the reverse osmosis membrane part And at least a factor value detecting means for detecting a water temperature, a required water quality determining means for determining a required water quality of the device for treated water, and a flow rate detecting means for detecting a treated water flow rate of the reverse osmosis membrane part. The control means includes a first step of setting the mutual relational characteristics of the treated water flow rate, the water temperature, and the treated water quality of the reverse osmosis membrane unit, the water temperature by the factor value detecting means, and the request by the required water quality judging means. Based on water quality Performing a second step of calculating a predetermined flow rate satisfying the required water quality from the relationship characteristics, and a third step of controlling the number of revolutions of the pump so that the detected flow rate of the flow rate detection means becomes the predetermined flow rate. It is a feature.

According to the first aspect of the present invention, the predetermined flow rate that satisfies the required water quality and realizes energy saving can be easily calculated from the relational characteristics of the reverse osmosis membrane portion. As a result, energy consumption can be easily realized by reducing the power consumption of the pump while satisfying the required water quality of the treated water. In addition, the one that detects the quality of the treated water and performs feedback control may cause hunting in response, but according to the invention described in claim 1, the number of rotations of the pump is controlled so as to achieve the predetermined flow rate. Therefore, compared with what detects the treated water quality and controls it to become a predetermined treated water quality, there is an effect that stable water quality and flow rate control can be performed.

  The invention according to claim 2 is characterized in that, in claim 1, the predetermined flow rate is a minimum flow rate satisfying the required water quality.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, there is an effect that the maximum energy saving can be realized by setting the predetermined flow rate to the minimum flow rate.

  According to a third aspect of the present invention, in the second aspect, the control means controls the number of rotations of the pump so that the required treated water flow rate is obtained when the required treated water flow rate of the device exceeds the minimum flow rate. It is characterized by.

  According to the third aspect of the present invention, in addition to the effect of the second aspect of the invention, when the required treated water flow rate exceeds the minimum flow rate, the required treated water flow rate and the required water quality can be satisfied. There is an effect.

  According to this invention, the power consumption of the pump can be reduced while maintaining the quality of the treated water, and energy saving can be easily realized.

It is a schematic block diagram of Example 1 of the water quality modification system which implemented this invention. It is a flowchart figure which shows the principal part of the control procedure of the Example 1. FIG. It is a figure explaining the relationship between the treated water tank water level of the same Example 1, and an operation mode. It is the characteristic figure of the permeation | transmission ratio which used the flow rate ratio and the water temperature of the Example 1 as a parameter. It is a water quality characteristic figure which made the flow rate ratio and water temperature of Example 1 the parameter. It is an effective operation pressure characteristic figure which made the flow rate ratio and water temperature of Example 1 the parameter. It is an energy-saving ratio characteristic figure which made the flow rate ratio and water temperature of the Example 1 the parameter. It is a schematic block diagram of Example 2 of the water quality modification system which implemented this invention. It is a schematic block diagram of the principal part of the Example 2. It is a schematic block diagram of Example 3 of the water quality modification system which implemented this invention.

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 part 10 Pump 11a Flow rate sensor 11b Water temperature sensor 11c Inlet pressure sensor 11d Outlet back pressure sensor 11e Electric conduction sensor 12 First controller

  An embodiment of the present invention will be described. The embodiment of the present invention can be suitably 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).

(Embodiment 1)
Embodiment 1 of the present invention includes a reverse osmosis membrane part that supplies treated water from which impurities in the treated water are removed to a device, a pump that supplies treated water to the reverse osmosis membrane part, and the rotational speed of the pump A water quality reforming system comprising a control means for controlling the water quality, and a factor value detection means for detecting a change in a value of a change factor (change factor) of the quality of the treated water (treated water quality) of the reverse osmosis membrane portion And a required water quality determining means for determining the required water quality of the device for treated water, and a flow rate detecting means for detecting a flow rate of treated water in the reverse osmosis membrane part, wherein the control means includes the reverse osmosis membrane part. A first step of setting mutual relational characteristics of the treated water flow rate, water temperature and treated water quality, and a second step of calculating a predetermined flow rate satisfying the required water quality from the relational characteristics based on the required water quality by the required water quality judging means And the flow rate detection hand Detected flow of a water reforming system and carrying out the third step of controlling the rotational speed of the pump so that the predetermined flow rate. Here, the water to be treated and the treated water mean water before being treated in the reverse osmosis membrane part and water after being treated, respectively.

  In the first embodiment, assuming that the use environment has almost no change in the quality of the water to be treated, the change factors are treated water flow rate, water temperature, and membrane performance of the reverse osmosis membrane portion, and the factor value detection is performed. In the case where the means is a water temperature detecting means and a membrane performance detecting means, the first embodiment is preferably a water quality reforming system having the following configuration.

  The water quality reforming system includes a water temperature detecting means for detecting a water temperature as the factor value detecting means, a membrane performance detecting means for detecting the membrane performance of the reverse osmosis membrane section, and a required water quality determination for determining a required water quality of the device. And flow rate detection means for detecting the flow rate of the treated water in the reverse osmosis membrane part, and the control means is a mutual relationship between the treated water flow rate, water temperature, membrane performance and treated water quality of the reverse osmosis membrane part. Based on the first step of setting the characteristics, the required water quality by the required water quality determining means, the detected water temperature by the water temperature detecting means, and the membrane performance by the membrane performance detecting means, a predetermined flow rate that satisfies the required water quality from the relational characteristics is determined. A second step of calculating and a third step of controlling the number of revolutions of the pump so that the detected flow rate of the flow rate detecting means becomes the predetermined flow rate are performed. The membrane performance detecting means preferably detects a transmittance or a removal rate.

  The relational characteristic of the reverse osmosis membrane part can be expressed as the water quality characteristic of the treated water using the flow rate ratio and the water temperature as parameters. 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 (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 ion transmission rate are preferably obtained in real time, but the ion transmission rate is calculated from data such as during a trial run and is input to the storage means inside or outside the control means, and this is inputted under certain conditions (for example, , And the initial ion permeability under a water temperature of 25 ° C. or the like. 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. Can be requested. This water quality characteristic is a characteristic using a change factor including a flow rate ratio as a parameter. The water quality characteristics (relationship characteristics) thus determined are stored in the storage means.

  Since the “flow rate ratio” in this water quality characteristic is equivalent to the treatment flow rate and has a predetermined relationship with the operation pressure, it can be expressed by replacing the “flow rate ratio” with the treatment water flow rate or the operation 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.

  In the first embodiment, the change factor includes at least the treated water flow rate and the water temperature, and preferably further includes the membrane performance. However, the factor value detection means is a sensor or a measuring instrument for detecting the value of the change factor. Can do. Which change factor is selected is determined according to the environment in which the water quality reforming system is used. The temperature of the water to be treated is detected by a water temperature sensor as a water temperature detecting means, but may be configured to be indirectly detected based on the temperature of the treated water or the temperature of the drainage (concentrated water) from the reverse osmosis membrane. it can. The quality of the water to be treated is detected by a water quality sensor that detects the concentration of the component removed by the reverse osmosis membrane (preferably, a conductivity sensor, a hardness sensor or a sensor that detects the silica concentration).

  The membrane performance detecting means for each reverse osmosis membrane as the factor value detecting means detects the state of the membrane performance due to clogging of the membrane and deterioration of the membrane including the individual differences. This membrane performance can be detected based on the quality of treated water (electrical conductivity), removal rate (ratio from which ion components are removed) or permeability, 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.

The transmittance will be described. The membranes of the reverse osmosis membrane portions have initial reference performance (initial characteristics) due to solid differences. This initial reference performance can be expressed by an initial reference transmittance. The initial reference transmittance can be obtained by the control unit through the water at the start of system use, but before the system is shipped, the initial reference transmittance is obtained and input for each reverse osmosis membrane unit. I can leave.
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. This transmittance and removal rate can be referred to as ion transmittance and ion removal rate, respectively.

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 reverse osmosis 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) × water temperature correction factor X × pressure (flow rate) correction factor × deterioration correction factor Y

  This deterioration correction coefficient Y = current reference transmittance / initial reference transmittance can be obtained. The 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 electrical conductivity between the inlet side and the outlet side of each reverse osmosis membrane part by the electrical 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 relational characteristic can be obtained as a water quality characteristic of treated water using the flow rate ratio, the water temperature, and the membrane performance of the reverse osmosis membrane part as parameters. Specifically, the characteristic of the treated water obtained by changing the water temperature and the flow rate ratio of the reverse osmosis membrane part is the water quality characteristic, and the deterioration correction coefficient based on the detected membrane performance with respect to this water quality characteristic It can be obtained by correcting with Y. The deterioration correction coefficient (film deterioration coefficient) Y is preferably the detection film performance / initial film performance as described above.

  When the water quality characteristic is expressed in a table, the water quality characteristic can be corrected by multiplying the value in this table by Y.

The case where the water quality characteristic is expressed by an expression (function) will be described. The expected water quality of the water quality characteristics with flow rate ratio and water temperature as parameters can be obtained by the following relational expression.
Expected water quality = α × K × degradation correction coefficient Y
Where α is the water quality at a specific water temperature and specific flow rate ratio, and K is the ion permeation ratio.

  In the water quality reforming system of this embodiment, the control means performs the first step. This first step is to determine and set the interrelated characteristics of the treated water flow rate, water temperature, membrane performance and treated water quality of the reverse osmosis membrane part. This setting includes the following two methods. The first method is a method in which mutual relational characteristics of treated water flow rate, water temperature, membrane performance and treated water quality are obtained in advance, stored in the storage means, and the stored relational characteristics are read and set. In the second method, the mutual performance characteristics of the treated water flow rate, the water temperature, and the treated water quality are obtained in advance, stored in the storage means, the relation characteristics are read out, and the membrane performance detected by the membrane performance detection means. This is a method for correcting this relational characteristic.

  In the second step, the required water quality of the device set in advance or the required water quality from the device that changes is determined by the required water quality determination means, the detected water temperature detected by the water temperature detection means, Based on the membrane performance detected by the membrane performance detecting means, a predetermined flow rate that satisfies the required water quality is calculated from the relational characteristics.

  In the third step, the rotational speed of the pump is feedback-controlled so that the flow rate detected by the flow rate detection means becomes the predetermined flow rate. The predetermined flow rate is the minimum flow rate (minimum flow rate) of the treated water flow rate that satisfies the required water quality from the viewpoint of energy saving.

  According to this water quality reforming system, a predetermined flow rate that satisfies the required water quality can be easily calculated from the relational characteristics. This predetermined flow rate can be set to the minimum flow rate that satisfies the required water quality as much as possible, reducing the power consumption of the pump while maintaining the quality of the treated water regardless of changes in the water temperature and membrane performance, and simplifying energy saving. Can be realized.

  In this water quality reforming system, the operation mode for operation at the minimum flow rate is energy saving operation. This energy-saving operation is an operation under conditions that do not take into account the required treated water flow rate of the equipment. For example, a treated water tank holding system that stores treated water in the treated water tank and then supplies treated water to the equipment. In the case where the water level of the treated water tank is equal to or higher than the first set water level, etc.

In this water quality reforming system, preferably, non-energy-saving operation is added in addition to the energy-saving operation. In this non-energy-saving operation, when the required treatment water flow rate for the reverse osmosis membrane portion exceeds the minimum flow rate of the reverse osmosis membrane portion, the required treatment water flow rate is increased by increasing the rotation speed of the pump of the reverse osmosis membrane portion. It can be set as the driving | running controlled to become. This non-energy-saving operation is performed in the treated water tank holding system when the water level of the treated water tank is lower than the second set water level (<first set water level). This non-energy-saving operation is preferably a rated flow rate operation of the reverse osmosis membrane part, but can be a flow rate that is less than the rated flow rate and greater than the minimum flow rate. In this case, recovery of the water level of the treated water tank is delayed. In energy saving operation, the flow rate can be slightly higher than the minimum flow rate. In this case, the energy saving effect is reduced.

  The energy-saving operation is an operation for controlling the pump at a low rotational speed while satisfying the required water quality, and the non-energy-saving operation is an operation for controlling the pump so as to satisfy the required water quality while satisfying the required water quality. It is.

  Here, the reason why energy saving is achieved when the treated water flow rate is lowered will be described. The operating pressure characteristic with the flow rate ratio (treated water flow rate) of the reverse osmosis membrane part and the water temperature as parameters is the operating pressure required to obtain the treated water flow rate as the flow rate ratio increases when the water temperature is constant. Shows a tendency to increase. When the flow rate ratio is constant, the operation pressure required to obtain the flow rate ratio tends to decrease as the water temperature rises.

On the other hand, the power consumption of the pump is proportional to the 1.5th power of the operating pressure. Therefore, the energy saving ratio = (W2 / W1) ∝ (P2 / P1) ^1.5 . Here, W1 is the reference power consumption at the reference treated water flow rate of the pump, W2 is the power consumption at the treated water flow rate to be compared with the pump, and P1 and P2 are operations corresponding to W1 and W2, respectively. Pressure. That is, the energy saving ratio decreases as the treated water flow rate decreases (energy saving). Since the lower level is 1.5 power of the treated water flow rate, the energy saving effect by reducing the treated water flow rate is great.

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

  The reverse osmosis membrane portion may be a filtration device having a reverse osmosis membrane portion that removes ionic components by a reverse osmosis membrane such as a nanofiltration membrane, and is not limited to a filtration device having a specific structure.

  The pump is not limited to a specific pump as long as the rotation speed can be controlled. The rotational speed is preferably controlled by an inverter.

  The present invention is not limited to the first embodiment described above, but includes the following second and third embodiments.

(Embodiment 2)
The second embodiment is the same as the first embodiment, wherein the water quality reforming system is provided with a plurality of reverse osmosis membrane parts connected in parallel to each other and the reverse osmosis membrane part for each of the water to be treated. It is comprised from the pump supplied to an osmosis membrane part.

  In the second embodiment, a relational characteristic is obtained for each of the reverse osmosis membrane units, and, similarly to the first embodiment, the control means controls the pumps so that the treated water flow rate becomes the predetermined flow rate. Control the number of revolutions. Then, the factor value detection means is the membrane performance detection means, and by including the membrane performance as a factor in the relational characteristic, the flow rate control considering the change in the membrane performance can be performed.

  According to the second embodiment, the effect of the first embodiment is obtained by connecting a plurality of reverse osmosis membrane portions connected in parallel and the water to be treated provided for each of the reverse osmosis membrane portions to the reverse osmosis membrane portion. This can be realized in a reforming system including a pump to be supplied.

(Embodiment 3)
The third embodiment is the same as the first embodiment, in which the water quality reforming system is connected in parallel to each other and has a plurality of reverse osmosis membrane portions having the same relational characteristics, and is common to the respective reverse osmosis membrane portions. And a pump for supplying the water to be treated to each of the reverse osmosis membrane portions.

  In the third embodiment, as in the first embodiment, the control means controls the rotation speed of each pump so that the treated water flow rate becomes the predetermined flow rate from the relational characteristics of the reverse osmosis membrane portion. To do.

  According to the third embodiment, the effects of the first embodiment are obtained by combining the plurality of reverse osmosis membrane portions connected in parallel and the respective reverse osmosis membrane portions with the water to be treated provided in the respective reverse osmosis membranes. This can be realized in a reforming system including a pump for supplying to the section.

  Embodiment 1 of the water quality reforming system of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of the first embodiment. FIG. 2 is a flowchart for explaining the control procedure of the first embodiment. FIG. 3 is a diagram for explaining the relationship between the treated water tank water level and the operation mode of the first embodiment. 4 is a characteristic diagram of the permeation ratio with the flow rate ratio and the water temperature of the first embodiment as parameters, and FIG. 5 is a water quality characteristic diagram with the flow ratio and the water temperature of the first embodiment as parameters. FIG. 7 is an effective operation pressure characteristic diagram with the flow rate ratio and water temperature of the first embodiment as parameters, and FIG. 7 is an energy saving ratio characteristic diagram with the flow rate ratio and water temperature of the first embodiment as parameters.

  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 apparatus 4 connected to this water supply line 3, the soft water apparatus 5, the prefilter 6, the reverse osmosis membrane part 9, and the treated water tank 8 which stores the treated water supplied to the said heat apparatus 2; It is configured with. 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 the reverse osmosis membrane unit 9 is referred to as a treated water line 3-1, and the downstream side of the reverse osmosis membrane unit 9 is referred to as a treated water 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.

  The reforming system includes a pump 10 connected to the upstream side of the reverse osmosis membrane unit 9, various detectors 11 (11a to 11e) connected to the upstream side and the downstream side of the reverse osmosis membrane unit 9, An inverter (not shown) connected to the pump 10 and a first controller 12 that controls the pump 10 and the like are provided. Hereafter, each said structure is demonstrated.

  The said reverse osmosis membrane part 9 is provided with the nanofiltration membrane (NF membrane, NF: Nanofiltration) as a filtration member.

Water supplied from the pump 10 flows into one end of the reverse osmosis membrane portion 9. In the supplied water, inside the reverse osmosis membrane portion 9, the nanofiltration membrane captures the corrosion promoting component as a filtration component and allows the corrosion inhibiting component to permeate. From the other end of the reverse osmosis membrane portion 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 feed water from which dust and the like flowing through the water to be treated 3-1 on the downstream side of the prefill 6 are removed. The output frequency is variable according to the output frequency output from the inverter.

  The various detectors 11 include a flow rate sensor 11a, a water temperature sensor 11b, an inlet pressure sensor 11c, an outlet pressure sensor 11d, and electrical conduction sensors 11e and 11f. The flow sensor 11 a detects the amount of permeated water that has passed through the reverse osmosis membrane unit 9 and outputs a flow rate detection signal to the first controller 12, and is downstream of the reverse osmosis membrane unit 9. Is connected to the 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 the reverse osmosis membrane portion 9 and the treated water line 3 on the downstream side of the reverse osmosis membrane portion 9 are used. -, Connected to any one of the drainage lines 13, and in this embodiment 1, connected to the treated water line 3-1 upstream of the reverse osmosis membrane 9 and upstream of the pump 10. ing. 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 reverse osmosis membrane part 9, respectively, and the pressure of the feed water And a pressure detection signal is output to the first controller 12.

  The electrical conductivity sensors 11e and 11f are connected to the treated water line 3-2 on the downstream side of each reverse osmosis membrane unit 9 and the treated water line 3-1 on the upstream side, respectively. The electric conductivity of the permeated water and the water to be treated that has passed through is detected and the detection 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 a membrane performance detection unit that detects a permeation flux. The electrical conductivity sensors 11e and 11f function as membrane performance means for detecting ion permeability (removal rate).

  The first controller 12 includes a CPU, storage means (ROM, RAM), and an interface. The storage means stores in advance the relational characteristics of the treated water flow rate ratio, the water temperature of the reverse osmosis membrane part 9 and the treated water quality of the reverse osmosis membrane part, the relational characteristic being the reverse osmosis membrane It is the water quality characteristic of the treated water which used the flow rate ratio and water temperature of the part as parameters.

  In the first 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. 4, 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). And by setting the value of water quality (mg / L) at a water temperature of 25 ° C. and a flow rate ratio of 100% to 10.9 (when the treated water quality and recovery rate are constant), this value is multiplied by the correction coefficient K, As shown in FIG. 5, the water quality (mg / L) is obtained using the water flow rate ratio and the water temperature as parameters. This is stored in the storage means as water quality characteristics.

  The first controller 12 inputs signals from the various detectors 11a to 11f and the water level sensor 15, and executes the flow rate control procedure shown in FIG. 2 stored in the storage means.

  This flow rate control procedure sets the relational characteristics of the treated water flow rate ratio, the water temperature, the membrane performance of the reverse osmosis membrane unit 9 and the treated water quality of the reverse osmosis membrane unit 9 in the reverse osmosis membrane unit 9. A second step of calculating a predetermined flow rate satisfying the required water quality Q1 from the relational characteristics based on the step, the required water quality Q1 of the thermal device 2, the detected water temperature by the water temperature sensor 11b, and the membrane performance by the membrane performance detecting means. And a third step of controlling the rotational speed of the pump 10 so that the detected flow rate of the flow rate sensor 11a becomes the predetermined flow rate. In the first embodiment, the predetermined flow rate is the minimum flow rate that is the minimum value of the treated water flow rate that satisfies the required water quality Q1.

  This flow rate control procedure includes a control procedure for performing stop, energy saving flow rate operation, and rated flow rate operation according to the detected water level of the water level sensor 15. The control procedure is configured as follows.

  That is, as shown in FIG. 3, when the water level of the treated water tank 8 rises, when the water level is lower than the first water level L, the pump 10 is operated at a rated flow rate, and when the water level is equal to or higher than the first water level L + A, When the energy saving operation is performed and the water level is equal to or higher than the second water level H, control for stopping the pump 10 is performed.

  Further, the first controller 12 determines whether or not the required water quality Q1 is satisfied based on the detection signal of the electrical conductivity sensor 11a. If not, the first controller 12 is used by a reporting means (not shown). Also controls to notify the person. 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 in the energy saving operation so as to satisfy the required water quality Q1.

  Next, the operation of the first embodiment will be described below. (Overall Operation) The feed water that has flowed 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) is filtered in the reverse osmosis membrane section 9 to become treated water that can be supplied to the thermal equipment 2. Specifically, when water to be treated, which is soft water, passes through the nanofiltration membrane in the reverse osmosis membrane portion 9, corrosion promoting components such as sulfate ions and chloride ions are captured by the nanofiltration membrane. 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 operation)
Next, the operation of the first embodiment based on the control procedure of FIG. 2 will be described. In processing step S1 (hereinafter, processing step SN is simply referred to as SN), the required water quality Q1 of the thermal device 2 set in advance and stored in the storage means is read (determined). In S2, the water temperature is detected by the water temperature sensor 11a.

In S3, the membrane performance is detected, that is, the ion transmittance is calculated. The calculation of the ion transmittance is performed as follows. The value obtained by subtracting the detection value of the downstream conductivity sensor 11e from the detection value of the upstream conductivity sensor 11f of each reverse osmosis membrane portion 9 is divided by the detection value of the upstream conductivity sensor 11f. Thus, the ion removal rate is obtained, and the ion transmittance is calculated by (100−ion removal rate).

  In S4, the water quality characteristic as shown in FIG. 6 stored in the storage means is read out. In S5, the value of the ion permeability detected in S3 is used as the initial ion permeability of each reverse osmosis membrane section 9. Correction is performed by a correction coefficient Y divided by the value of the rate (ion transmittance at the time of product shipment). Specifically, the water quality characteristic is corrected by multiplying the water quality value in FIG. 6 by Y. That is, the corrected water quality characteristic is obtained by 10.9 × K (ion transmission ratio) × Y. S4 and S5 correspond to the first step.

  Next, in S6, based on the required water quality Q1 determined in S1 and the detected water temperature in S2, the minimum flow rate that satisfies the required water quality Q1 is calculated from the water quality characteristics of FIG. 5 corrected by the ion permeability. Specifically, assuming that Y = 1, the required water quality Q1 is Q33, and the detected water temperature is 25 ° C., the water quality is Q33 from the column of the water temperature 25 ° C. in the table of FIG. Obtain the flow rate ratio. That is, when the required water quality is Q33, the flow rate ratio is 70%. 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). This S6 corresponds to the second step.

  In S7, based on the signal from the water level sensor 15, the first controller 12 determines the operation mode. If the water level of the treated water tank 8 is less than the first water level L, the rated flow operation is determined in S7, the process proceeds to S8, and the pump 10 is operated at the rated flow, that is, the flow rate ratio 100%. By this rated flow rate operation, treated water is supplied from the reverse osmosis membrane portion 9 to the treated water tank 8 at a maximum treated flow rate, so that the water level of the treated water tank 8 rises rapidly.

  When the water level of the treated water tank 8 is equal to or higher than the second water level (L + A), an energy-saving flow operation is determined in S7, the process proceeds to S9, and the first controller 12 sets the pump 10 to the treated water flow rate. Is controlled to be the minimum flow rate calculated in S6. That is, the rotational speed of the pump 10 is feedback-controlled using the inverter so that the detected flow rate of the flow rate sensor 11a becomes the minimum flow rate. This S9 corresponds to the third step.

  Here, the reason why energy saving is realized by controlling the pump 10 so that the treated water flow rate becomes the minimum flow rate 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 parameters. The operating pressure characteristics are as shown in FIG. 6, for example. 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 characteristic is as shown in FIG. 6, 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.

Further, when the water level of the treated water tank 8 is equal to or higher than the third water level H, it is determined in S7 that the water is stopped, and the pump 10 is stopped. When the water level of the treated water tank 8 falls, every time the third water level and the second water level fall below a predetermined differential from the stop,
Control that energy-saving operation → rated flow operation is performed.

  According to the water quality reforming system of the first embodiment, the minimum flow rate that satisfies the required water quality Q1 can be easily calculated from the water quality characteristics. And, regardless of changes in water temperature and membrane performance, the power consumption of the pump can be reduced while maintaining the quality of the treated water, and high energy saving can be easily realized. Moreover, since the flow rate control considering the change in membrane performance can be performed for each reverse osmosis membrane portion 9, the quality of the treated water in the reverse osmosis membrane portion 9 can be made uniform while satisfying the required water quality Q1.

  In addition, since the change in the treated water quality is captured by the treated water flow rate and the rotational speed of the pump 10 is controlled so as to be the predetermined flow rate, the treated water quality is detected and the predetermined treated water quality is determined. Compared with what controls so that it becomes, there is little possibility of hunting, and stable water quality and flow rate control can be performed.

  As shown in FIGS. 8 and 9, the second embodiment is configured such that, in the first embodiment, the water quality reforming system includes a plurality of membrane filtration devices 7, 7,. As shown in FIG. 9, each of the membrane filtration devices 7 includes the reverse osmosis membrane portion 9, the pump 10, the various detectors 11, the drainage line 13, and the circulation line 14, respectively. . In the following, the second embodiment will be described with a focus on differences from the first embodiment.

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

  The second controller 19 for overall control of the system is connected to each first controller 12 of each membrane filtration device 7 shown in FIG. 9 to control each membrane filtration device 7 and each electromagnetic The 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.

  In the second embodiment, the second controller 19 sends stop, energy saving flow rate operation, and rated flow rate operation signals to the first controller 12 in accordance with the detected water level of the water level sensor 15, and the membrane filtration. The apparatus 7 is controlled. The control procedure is configured as follows.

  That is, as shown in FIG. 4, when the water level of the treated water tank 8 rises, when the water level is less than the first water level L, the first command for operating the pumps 10 at the rated flow rate is set to the first water level L + A or higher. Then, the second command for causing the pumps 10 to perform the energy saving operation and the third command for stopping the pumps 10 when the water level H is equal to or higher than the second water level H are controlled to be transmitted to the first controller 12. The second controller 19 determines whether or not the required water quality Q1 is satisfied based on the detection signal of the second electrical conductivity sensor 17, and the treated water flow rate is satisfied based on the detection signal of the flow sensor 18. In the case where it is not satisfied, as in the first embodiment, the notification means is also used to notify the user.

  The first command can be considered to be the total required treatment water flow rate for the system of Example 1 as the rated flow rate of the reverse osmosis membrane unit 9 × the number of the reverse osmosis membrane units 9. Further, the second command can be considered that there is no total required treated water flow rate.

The control procedure of the second controller 19 includes a control for closing each electromagnetic valve 16 when the reverse osmosis membrane portion 9 needs to be cleaned, and opening the others.

  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.

  In this Example 2, the said relational characteristic is calculated | required for every said reverse osmosis membrane part 9, and similarly to the said Example 1, the said controllers 12 and 19 are the treated water flow rates of each said reverse osmosis membrane part 9. The number of rotations of each pump 10 is controlled so that the predetermined flow rate is achieved. Then, the factor value detection means is the membrane performance detection means, and by including the membrane performance as a factor in the relational characteristic, the flow rate control considering the change in the membrane performance can be performed.

  As shown in FIG. 10, the third embodiment includes a plurality of reverse osmosis membrane portions 9 (9-1, 9-1) having the same relational characteristics in which the water quality reforming systems are connected in parallel to each other in the first embodiment. 9-2, 9-3) and a pump 10 that is provided in common to each of the reverse osmosis membrane units 9 and supplies treated water to each of the reverse osmosis membrane units. . In the following description, the third embodiment will be described with a focus on the differences from the first and second embodiments.

  Referring to FIG. 10, electromagnetic valves 16 (16-1, 16-2, 16-3) are provided on the downstream side of each reverse osmosis membrane unit 9, and these are controlled by the first controller 12. It is configured to do.

  In the third embodiment, as in the first embodiment, the first controller 12 is configured such that the treated water flow rate detected by the flow sensor 11a from the relational characteristics of the reverse osmosis membrane unit 9 becomes the predetermined flow rate. Thus, the rotation speed of the pump 10 is controlled.

  It goes without saying that the present invention can be variously modified without departing from the spirit of the present invention. That is, in the first embodiment, the following configuration can be added as described in JP-A-2008-658. The structure includes a reverse osmosis membrane part for removing impurities in the feed water, drains 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 part or the permeated water amount from the reverse osmosis membrane part. 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 wasteful power consumption in the pump for supplying water to the reverse osmosis membrane part, and to maintain the flow velocity at the surface of the filtration membrane of the reverse osmosis membrane part. The filter membrane can be prevented from being clogged by the ring.

Claims (3)

A reverse osmosis membrane part that removes impurities in the water to be treated and supplies the treated water to the device, a pump that supplies the water to be treated to the reverse osmosis membrane part, and a control unit that controls the rotation speed of the pump A water quality reforming system,
A value of a factor of change in the quality of treated water in the reverse osmosis membrane portion, and a factor value detection means for detecting at least a water temperature;
A required water quality determination means for determining a required water quality of the equipment for treated water;
A flow rate detecting means for detecting the treated water flow rate of the reverse osmosis membrane part,
The control means sets the mutual characteristics of the treated water flow rate, the water temperature and the treated water quality of the reverse osmosis membrane part, the water temperature by the factor value detecting means and the required water quality by the required water quality judging means. And a second step of calculating a predetermined flow rate satisfying the required water quality from the relational characteristics, and a third step of controlling the rotational speed of the pump so that the detected flow rate of the flow rate detection means becomes the predetermined flow rate. Water quality reforming system characterized by this.   The water quality reforming system according to claim 1, wherein the predetermined flow rate is a minimum flow rate that satisfies the required water quality.   The water quality reforming according to claim 2, wherein the control means controls the number of rotations of the pump so that the required treated water flow rate is obtained when the required treated water flow rate of the device exceeds the minimum flow rate. system.

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