JP4367197B2 - Water treatment method - Google Patents

Description

  The present invention comprises a filtration part in a water supply line for supplying water to a thermal device such as a boiler, a membrane type deaeration part on the downstream side, and after filtering the corrosion promoting component in the filtration part of the feed water flowing through the water supply line, A water treatment method in which dissolved gas is degassed by a membrane-type degassing unit and water is supplied to a thermal device, and the corrosion promoting components dissolved in the feedwater flowing through the water supply line are filtered efficiently and the gas is degassed efficiently. The present invention relates to a water treatment method.

  In heat equipment such as a steam boiler, hot water boiler, cooling tower, and water heater, a large amount of water is generally consumed. In such a thermal device, a portion that comes into contact with the supplied water may be damaged due to corrosion due to the influence of the water supply, and the life of the thermal device may be fatally affected. The corrosion of the thermal equipment by water is mainly caused by corrosion promoting components such as chloride ions and sulfate ions contained in the feed water and oxygen dissolved in the feed water. Therefore, in order to stably operate and use the thermal equipment for a long time, it is necessary to effectively suppress the corrosion of the thermal equipment.

For this reason, conventionally, as a means for suppressing the corrosion of the thermal equipment, the corrosion caused by the corrosion promoting component contained in the water supply is described in, for example, Patent Document 1, Patent Document 2, and Patent Document 3. As shown in the figure, chemicals are added to the water supply to suppress it, and in the case of corrosion due to dissolved gas in the water supply, a degassing device is provided in the water supply line for supplying water to the heat equipment to remove the dissolved gas in the water supply. Suppress it.
JP-A-4-232286 JP-A-4-283299 JP-A-6-158366

  However, there is a possibility that a part of the chemical added to the water supply in order to suppress corrosion due to the corrosion promoting component contained in the water supply will be taken into the steam or hot water. From the viewpoint of hygiene, for example, it is difficult to use as it is in food cooking and processing applications. Moreover, although the chemical | medical agent added to feed water will be contained in feed water, for example, when discharging the concentrated water of feed water in a boiler, since this concentrated water contains the added chemical | medical agent, a chemical | medical agent is removed. Unless special treatment is performed, there is a problem that if it is discharged as it is into sewage, it may cause environmental pollution.

  Therefore, the inventors of the present application have conducted research on the suppression of corrosion by the corrosion promoting component contained in the water supply without using chemicals, and as a result, the nanofiltration membrane has been corroded by chloride ions and sulfate ions. It is found that the accelerating component is effectively captured and the silica recognized as the corrosion inhibiting component is permeated, and the above-mentioned filter membrane is considered as a means for suppressing the corrosion caused by the corrosion accelerating component contained in the water supply. It was. Furthermore, as a means for degassing the dissolved gas in the feed water, it was considered to use a membrane type deaeration part that evacuates through the gas permeable membrane. And the corrosion promoting component contained in the feed water is captured and filtered by the filtration membrane on the upstream side of the water supply line, and the dissolved gas is removed from the filtered water in which the corrosion promoting component is filtered on the downstream side. I thought to remove the dissolved oxygen by deaerating.

  However, there was one problem here. This is due to the properties of the filtration membrane that captures and filters the corrosion promoting components contained in the feed water, and the gas permeable membrane used in the membrane-type degassing part that degass the dissolved gas from the filtered water. . The ion removal performance (dissolved substance filtration performance) of the filtration membrane has a property that it decreases as the effective pressure decreases (water volume decreases) or the temperature of the feed water increases. Further, the permeability (degassing performance) of dissolved gas in water in the gas permeable membrane has a property that it decreases as the temperature of the feed water decreases or the flow rate of the feed water increases. For this reason, when the flow rate of the feed water decreases, the filtration performance of the corrosion promoting component of the filtration membrane may deteriorate, and the corrosion promoting component contained in the feed water may not be effectively filtered. When the temperature is lowered, the degassing performance of the dissolved gas by the gas permeable membrane is lowered, and it may not be possible to obtain a dissolved gas concentration that suppresses corrosion.

  The object of the present invention is to provide a filtration part on the upstream side of the water supply line for supplying water to the thermal equipment, a membrane type deaeration part on the downstream side, and promote corrosion according to the change in the temperature of the feed water flowing through the water supply line. An object of the present invention is to provide a water treatment method for efficiently filtering components and degassing dissolved gas.

  In order to achieve the above object, the water treatment method according to the first aspect of the present invention performs filtration using a filter membrane that captures a corrosion promoting component that causes corrosion of the thermal equipment upstream of the water supply line that feeds the thermal equipment. And a membrane-type deaeration unit that degassed by using a gas permeable membrane that allows the dissolved gas in the feed water to pass through, and the corrosion-promoting component is filtered by the filtration unit of the feed water flowing through the water supply line. Then, a water treatment method for degassing the dissolved gas in the membrane deaeration unit and supplying water to the thermal equipment, the flow after supplying the flow rate of the feed water, the temperature of the water supply, and the corrosion promoting component in the filtration unit The relationship between the corrosion promotion component residual value in water and the dissolved gas residual value in the permeated water after degassing the dissolved gas in the membrane-type deaeration unit is determined in advance, and the corrosion promotion component residual allowable value and dissolved gas residual value are determined. A water supply that flows through the water supply line after setting an allowable value. It detects the temperature, and controlling the feedwater flow rate to both satisfy the dissolved gas remaining allowable value and the corrosion promoting component remaining allowable value based on the water temperature.

  By doing in this way, since the flow rate of feed water is controlled so that both the said corrosion promotion component residual permissible value and dissolved gas residual permissible value are satisfied by the detected temperature of the feed water flowing through the said water supply line, The quality of the feed water supplied to the water can be improved to a quality that suppresses corrosion due to corrosion promoting components and suppresses corrosion due to oxygen in the dissolved gas.

  A water treatment method according to a second aspect of the present invention is the water treatment method according to the first aspect, wherein the reduction in the flow rate of the feed water flowing through the feed water line by detecting the temperature of the feed water flowing through the feed water line is at an arbitrary position of the feed water line. A temperature sensor for detecting the temperature of the feed water is provided, and a pump for supplying the feed water to the filtration unit is provided upstream of the filtration unit, and the rotation speed of the pump is variable according to the output frequency. An inverter for controlling the temperature sensor and an interface for the inverter, and a control unit for outputting a command signal to the inverter based on a temperature detection signal from the temperature sensor, and controlling based on a temperature detection signal for water supply from the temperature sensor The unit outputs a command signal to the inverter, and the rotation speed of the pump is varied by the inverter. .

  By doing in this way, water treatment can be performed automatically and the quality of the feed water supplied to the thermal equipment can be more reliably improved.

  The water treatment method according to the invention described in claim 3 is provided with a filtration section that filters using a filter membrane that captures corrosion promoting components that cause corrosion of the thermal equipment on the upstream side of the water supply line that feeds the thermal equipment. The membrane type deaeration part is provided with a membrane type deaeration part for deaerating on the side using a gas permeable membrane that allows the dissolved gas in the feed water to pass through. This is a water treatment method in which the feed water from which dissolved gas has been degassed is stored in a treated water tank and fed from the treated water tank to the thermal equipment, and the corrosion promoting components are filtered by the flow rate of the feed water, the temperature of the feed water, and the filtration unit. The relationship between the residual value of the corrosion promoting component in the filtered water and the residual value of the dissolved gas in the permeated water after degassing the dissolved gas in the membrane type deaeration part is determined in advance, and the allowable value of the residual corrosion promoting component is determined. And set the dissolved gas residual tolerance value. The required amount of water to be stored in the water tank is determined, the temperature of the water supply flowing through the water supply line is detected, and the residual corrosion promoting component residual value and the dissolved gas residual allowable value are both satisfied based on the temperature of the water supply. When the flow rate of the feed water is controlled and the amount of water in the treated water tank is detected to detect that the amount of water in the treated water tank is below the required amount of water, the temperature of the feed water exceeds the allowable dissolved gas residual value. Even if it becomes the temperature which shows a dissolved gas residual value, the flow volume of the feed water which flows through the feed water line sent out to a membrane type deaeration part is controlled.

  By doing in this way, since the flow rate of feed water is controlled so that both the said corrosion promotion component residual permissible value and dissolved gas residual permissible value are satisfied by the detected temperature of the feed water flowing through the said water supply line, The quality of the feed water supplied to the water can be improved to a quality that suppresses corrosion due to corrosion promoting components and suppresses corrosion due to oxygen in the dissolved gas. And when it is detected that the amount of water in the treated water tank is below the required amount of water, even if the temperature of the water supply becomes a temperature indicating a dissolved gas residual value exceeding the dissolved gas residual allowable value, Since the flow rate of the feed water flowing through the feed water line is not reduced, it is possible to avoid inconvenient situations due to insufficient feed water of the thermal equipment.

  A water treatment method according to a fourth aspect of the present invention is directed to the water treatment method according to the third aspect, wherein the reduction of the flow rate of the feed water flowing through the feed water line and the reduction of the flow rate of the feed water are performed by detecting the temperature of the feed water flowing through the feed water line. A pump having a temperature sensor for detecting the temperature of the feed water at an arbitrary position of the water supply line, a water amount sensor for detecting the amount of water in the treated water tank, and a pump for supplying the feed water to the filtration unit upstream of the filtration unit And an inverter connected to the pump for varying the rotational speed of the pump according to an output frequency, the temperature sensor, and an interface to the inverter, and a temperature detection signal from the temperature sensor and a water amount sensor. A control unit that outputs a command signal to the inverter based on the water supply amount detection signal is provided, and control is performed based on the temperature detection signal of the water supply from the temperature sensor. Outputs a command signal to the inverter, changes the pump rotation speed by the inverter, and releases the variable rotation speed of the pump based on the temperature detection signal based on the water supply amount detection signal from the water amount sensor. It is characterized by that.

  By doing in this way, water treatment can be performed automatically, reforming the quality of the feed water supplied to the thermal equipment, and reducing the flow rate of the feed water when the amount of water in the treated water tank falls below the required amount of water By avoiding the above, it is possible to more reliably avoid inconvenient situations due to insufficient water supply of the thermal equipment.

  According to the first aspect of the present invention, the flow rate of the feed water is controlled by the detected temperature of the feed water flowing through the feed water line so as to satisfy both the allowable corrosion promoting component residual value and the dissolved gas residual allowable value. Therefore, the quality of the feed water supplied to the thermal equipment can be improved to a quality that suppresses corrosion due to corrosion promoting components and suppresses corrosion due to oxygen in the dissolved gas. Moreover, according to the invention described in claim 2, water treatment can be performed automatically, and the quality of the water supplied to the thermal equipment can be more reliably improved. According to the invention described in claim 3, the flow rate of the feed water is controlled so as to satisfy both the allowable corrosion promoting component residual value and the dissolved gas residual allowable value based on the detected temperature of the feed water flowing through the feed water line. Therefore, the quality of the feed water supplied to the thermal equipment can be improved to a quality that suppresses corrosion due to corrosion promoting components and suppresses corrosion due to oxygen in the dissolved gas. And when it is detected that the amount of water in the treated water tank is below the required amount of water, even if the temperature of the water supply becomes a temperature indicating a dissolved gas residual value exceeding the dissolved gas residual allowable value, Since the flow rate of the feed water flowing through the feed water line is not reduced, it is possible to avoid inconvenient situations due to insufficient feed water of the thermal equipment. Further, according to the invention described in claim 4, water treatment can be performed automatically, reforming the quality of the water supplied to the thermal equipment, and avoiding unfavorable situations due to insufficient water supply of the thermal equipment. Can be performed more reliably.

Hereinafter, an example of the best mode for carrying out the water treatment method according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory diagram of a water treatment operation system for carrying out the present invention, and FIG. 2 is a flowchart showing an example of a water treatment system incorporating the water treatment operation system.
As shown in FIG. 2, the water treatment operation system 1 shown in FIG. 1 supplies water such as tap water, industrial water, and groundwater supplied from an external water source (not shown) to a steam boiler, hot water boiler, cooling tower, hot water supply. It is constructed on a water supply line 3 in a water quality reforming system that supplies heat equipment 2 such as a water heater.

  First, the water treatment system of FIG. 2 will be described. From the raw water side to the water supply line 3, an activated carbon filtration unit 4 that adsorbs and removes an oxidizing agent such as sodium hypochlorite dissolved in the water supply, and water supply water. The soft water treatment part 5 that removes hardness components such as calcium and magnesium contained in the water with an ion exchange resin, and captures corrosion promoting components such as chloride ions and sulfate ions contained in the water supply, as a corrosion inhibiting component A filtration unit 6 using a nanofiltration membrane that allows permeated silica, a membrane type deaeration unit 7 using a gas permeable membrane that transmits a gas such as oxygen dissolved in feed water, and a membrane type deaeration unit In order to prevent clogging of the nanofiltration membrane of the filtration unit 6 between the soft water treatment unit 5 and the filtration unit 6, a treated water tank 8 that stores the feed water that has passed through 7 is disposed in order. The filter 9 is arranged It is configured. In the water treatment system, although not shown, a sand filtration unit and an iron removal / manganese removal unit are disposed upstream of the activated carbon filtration unit 4 in accordance with the quality of water supplied from the outside. is doing.

  The nanofiltration membrane used in the filtration unit 6 will be described. The nanofiltration membrane is a synthetic polymer membrane such as polyamide or polyether. Further, the nanofiltration membrane is a liquid separation membrane that can prevent permeation of particles or polymers (having a maximum molecular weight of several hundreds) smaller than about 2 nm. In addition, the nanofiltration membrane includes an ultrafiltration membrane (a membrane capable of filtering out one having a molecular weight of about 1,000 to 300,000) and a reverse osmosis membrane (a molecular weight of about several dozens) in terms of its filtration function. It is a liquid separation membrane having a function located in the middle of a membrane that can be filtered off. Incidentally, nanofiltration membranes are commercially available from various companies and can be easily obtained.

  Further, in the membrane type deaeration unit 7 that evacuates through the gas permeable membrane, as a method of deaeration with respect to the gas permeable membrane, an internal perfusion method that sucks and deaerates from the water flowing outside, and an inner side Although there is an external perfusion method in which suction and deaeration is performed outward from flowing water, any method may be used.

  The water treatment operation system 1 is constructed on the filtration unit 6, the membrane deaeration unit 7, and the treated water tank 8 arranged in the water supply line 3 of the system 1 as follows.

  A temperature sensor 10 that detects the temperature of the water supply is provided between an arbitrary position of the water supply line 3, in this example, between the filtration unit 6 and the membrane deaeration unit 7. Further, a pump 11 that pressurizes and supplies the water supply to the filtration unit 6 and a water amount sensor 12 that detects the amount of water supply in the treated water tank 8 are provided upstream of the filtration unit 6. Furthermore, an inverter 13 connected to the pump 11 and capable of varying the rotational speed of the pump 11 according to an output frequency, the temperature sensor 10 and an interface to the inverter 13, a temperature detection signal from the temperature sensor 10, and A control unit 14 that outputs a command signal to the inverter 13 based on a water supply amount detection signal from the water amount sensor 12 is provided.

  The control unit 14 includes a flow rate of feed water flowing through the feed water line 3, a temperature of the feed water, a residual value of the corrosion promoting component in the filtered water after filtering the corrosion promoting component by the filtering unit 6, and the membrane type deaeration unit 7. Dissolved gas residual value in permeated water after degassing dissolved gas, corrosion promotion component residual allowable value and dissolved gas residual allowable value allowed for water supply used in specific heat equipment 2 determined in advance, treatment A storage unit (not shown) that stores the required water supply amount stored in the water tank 8 is provided.

  Furthermore, when the temperature of the feed water flowing through the feed water line 3 detected by the temperature sensor 10 becomes a temperature indicating the corrosion promoting component residual value or the dissolved gas residual value exceeding the corrosion promoting component residual allowable value or the dissolved gas residual allowable value, A command signal is output to the inverter 13 based on the temperature detection signal of the feed water from the temperature sensor 10, and the flow rate of the feed water sent to the membrane type deaeration unit 7 by the inverter 13 is set to allow the corrosion promoting component to remain. When the amount of water in the treated water tank 8 detected by the water amount sensor 12 is less than or equal to the required amount of water, the water amount sensor outputs a command signal for changing to a flow rate that can satisfy the value and the dissolved gas remaining allowable value. Based on the water amount detection signal from 12, a water supply reduction cancellation program for canceling the water supply reduction is provided.

  The water treatment method according to the present invention will be described using the water treatment operation system 1 configured as described above.

  A filtration unit 6 is provided on the upstream side of the water supply line 3 for supplying water to the thermal equipment 2, a membrane type deaeration unit 7 is provided on the downstream side thereof, and water is supplied to the filtration unit by a pump 11 provided on the upstream side of the filtration unit 6. 6, a flow rate set in advance is supplied, and the water supply flowing through the water supply line 3 is filtered through the filter unit 6 to remove corrosion promoting components, and then the dissolved gas is degassed by the membrane type deaeration unit 7. The water supply thus treated is stored in the treated water tank 8 and a water treatment operation for supplying water to the thermal equipment 2 is performed.

  The flow rate values at this time are 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 unit 6, and the dissolved gas in the membrane type deaeration unit 7. In the relationship with the dissolved gas remaining value in the permeated water after degassing, when the water supply is at the set water temperature, the corrosion promoting component remaining value and dissolved gas in the filtered water after filtering the corrosion promoting component are removed. The dissolved gas residual value in the permeated water after the gas is set to a flow rate that can satisfy the corrosion promoting component residual allowable value and the dissolved gas residual allowable value.

  In the course of the water treatment operation, for example, the temperature of the water supply decreases, and the temperature sensor 10 supplies the dissolved gas that exceeds the dissolved gas remaining allowable value stored in the storage unit at the set flow rate of the water supply. When it is detected that the temperature indicates the remaining value, the control unit 14 outputs a command signal to the inverter 13 according to the water supply reduction program based on the temperature detection signal from the temperature sensor 10, and the inverter 13 rotates the rotation speed of the pump 11. The amount of the feed water supplied is varied, and the dissolved gas remaining value does not exceed the permissible dissolved gas residual value within the range in which the filtration of the corrosion promoting component by the filtering unit 6 satisfies the allowable corrosion residual component allowable value. To lose weight.

  By doing in this way, the degassing of the dissolved gas by the membrane-type degassing unit 7 is improved, and the decrease in the performance of removing the dissolved gas due to the lower temperature of the feed water is offset, and the corrosion promoting component by the filtering unit 6 In the state where the filtration satisfies the allowable corrosion promoting component residual value, the dissolved gas residual value in the feed water can be maintained at a value not exceeding the dissolved gas residual allowable value.

  After this, when the temperature of the feed water rises and the dissolved water remaining value in the feed water after degassing the dissolved gas reaches a temperature at which the dissolved gas remaining allowable value can be satisfied even if the feed water reaches the set flow rate The temperature sensor 10 detects this, and based on this temperature detection signal, the control unit 14 outputs a command signal to the inverter 13 according to the water supply reduction program, and the inverter 13 varies the number of rotations of the pump 10 to supply water. Return the supply amount to the set flow rate.

  In addition, a water amount sensor 12 that detects the amount of water in the treated water tank 8 during the operation of changing the rotation speed of the pump 11 to reduce the amount of supplied water due to a decrease in the temperature of the supplied water is a water amount in the treated water tank 8. Is detected to be less than the required amount of water, the control unit 14 cancels the water supply reduction based on the water supply amount detection signal from the water amount sensor 12, and the rotation speed of the pump 11 based on the temperature detection signal is canceled. Release variable.

  By doing in this way, when the amount of water in the treated water tank 8 falls below the required amount of water, it is possible to avoid various disadvantageous situations due to insufficient water supply of the thermal equipment 2 by avoiding a decrease in the flow rate of the water supply.

  As described above, according to the water treatment method of the present invention, the filtration unit 6 is provided on the upstream side of the water supply line 3 for supplying water to the thermal equipment 2, and the membrane type deaeration unit 7 is provided on the downstream side thereof. At the time of water quality reforming operation for reforming the quality of the feed water, when the temperature of the feed water flowing through the feed water line 3 becomes low and reaches a temperature indicating a dissolved gas residual value exceeding the allowable dissolved gas residual value, a membrane type deaeration unit The flow rate of the feed water sent to 7 is reduced to an amount that shows a dissolved gas residual value that does not exceed the dissolved gas residual allowable value within a range in which the filtration of the corrosion promoting component by the filtration unit satisfies the corrosion promoting component residual allowable value. Therefore, the degassing of the dissolved gas is improved and the decrease in the degassing performance of the dissolved gas due to the lower temperature of the feed water is offset, so that the dissolved gas remaining value in the feed water does not exceed the allowable dissolved gas remaining value. Thermal equipment that can be maintained, even when the water supply is cold Water supply water quality supplied to, suppresses corrosion caused by corrosion promoting component, it can be modified to inhibit water corrosion due to dissolved gas. And when it detects that the amount of water of the treated water tank 8 has fallen below the required amount of water, even if the temperature of the said water supply becomes the temperature which shows the dissolved gas residual value exceeding a dissolved gas residual allowable value, a membrane type deaeration part 7, the flow rate of the feed water flowing through the feed water line 3 that is sent to 7 is not reduced, so that various inconveniences due to a lack of feed water of the thermal device 2 can be avoided.

The schematic explanatory drawing of the water treatment operation system which enforces the water treatment method concerning the present invention. The flow which shows an example of the water treatment system incorporating the water treatment operation system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water treatment operation system 2 Thermal equipment 3 Water supply line 4 Activated carbon filtration part 5 Soft water treatment part 6 Filtration part 7 Membrane type deaeration part 8 Treated water tank 9 Filter 10 Temperature sensor 11 Pump 12 Water quantity sensor 13 Inverter 14 Control part

Claims (4)

A gas permeable membrane that has a filtration part that filters using a filter membrane that captures corrosion-promoting components that cause corrosion of the thermal equipment on the upstream side of the water supply line that supplies water to the thermal equipment, and that permeates dissolved gas in the feed water on the downstream side A membrane-type deaeration unit that degass using the filter, and after the corrosion-promoting component is filtered by the filtration unit of the feed water flowing through the water supply line, the dissolved gas is deaerated at the membrane-type deaeration unit and supplied to the thermal equipment A water treatment method,
The flow rate of 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 in the filtration unit, and the dissolved gas in the permeated water after degassing the dissolved gas in the membrane type deaeration unit The relationship with the residual value is determined in advance, the corrosion promoting component residual allowable value and the dissolved gas residual allowable value are determined, the temperature of the feed water flowing through the water supply line is detected, and the corrosion is determined based on the temperature of the feed water. A water treatment method, wherein the flow rate of feed water is controlled so as to satisfy both the acceleration component residual allowable value and the dissolved gas residual allowable value.   The reduction of the flow rate of the feed water flowing through the feed water line by detecting the temperature of the feed water flowing through the feed water line includes a temperature sensor for detecting the feed water temperature at an arbitrary position of the feed water line, and the upstream side of the filtration unit A pump for supplying water to the filtration unit; an inverter connected to the pump for changing a rotation speed of the pump according to an output frequency; and an interface for the temperature sensor and the inverter. A control unit that outputs a command signal to the inverter based on a temperature detection signal is provided, and the control unit outputs a command signal to the inverter based on a temperature detection signal of feed water from a temperature sensor, and the inverter rotates the pump speed. The water treatment method according to claim 1, wherein the water treatment method is performed. A gas permeable membrane that has a filtration part that filters using a filter membrane that captures corrosion-promoting components that cause corrosion of the thermal equipment on the upstream side of the water supply line that supplies water to the thermal equipment, and that permeates dissolved gas in the feed water on the downstream side The membrane type deaeration part is used to deaerate, and after the corrosion promoting component is filtered by the filtration part of the feed water flowing through the water supply line, the feed water from which the dissolved gas is deaerated by the membrane type deaeration part is supplied to the treated water tank A water treatment method for storing and supplying water to a thermal device from a treated water tank,
The flow rate of 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 in the filtration unit, and the dissolved gas in the permeated water after degassing the dissolved gas in the membrane type deaeration unit A relationship with the residual value is obtained in advance, a corrosion promoting component residual allowable value and a dissolved gas residual allowable value are determined, and further, a necessary water supply amount stored in the treated water tank is determined and flows through the water supply line. The temperature of the feed water is detected, and the flow rate of the feed water is controlled based on the temperature of the feed water so as to satisfy both the allowable value for remaining corrosion promoting components and the allowable value for residual dissolved gas, and the amount of water in the treated water tank is detected. When the water amount in the treated water tank is detected to be lower than the required water amount, even if the temperature of the feed water reaches a temperature indicating a dissolved gas residual value exceeding the dissolved gas residual allowable value, the membrane deaeration unit The water supply line Water treatment method and controlling the feedwater flow rate of.   The reduction of the flow rate of the feed water flowing through the water supply line and the avoidance of the reduction of the flow rate of the feed water performed by detecting the temperature of the feed water flowing through the feed water line are provided with a temperature sensor for detecting the temperature of the feed water at an arbitrary position of the feed water line. A water amount sensor for detecting the amount of water in the water tank is provided, and a pump for supplying the water supply to the filtration unit is provided upstream of the filtration unit, and the number of rotations of the pump connected to the pump is determined according to an output frequency. An inverter to be varied, and a controller having an interface to the temperature sensor and the inverter, and outputting a command signal to the inverter based on a temperature detection signal from the temperature sensor and a water supply amount detection signal from the water amount sensor; Based on the temperature detection signal from the temperature sensor, the control unit outputs a command signal to the inverter. 4. The water according to claim 3, wherein the number of rotations of the pump is made variable, and the variable of the number of rotations of the pump based on the temperature detection signal is canceled based on a water supply amount detection signal from a water amount sensor. Processing method.

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