JP2013126632A - Method for generating and injecting diluted aqueous solution of sodium hypochlorite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for generating and injecting the diluted aqueous solution of sodium hypochlorite in which an acid is mixed to inhibit a scale generation and which is injected in a water to be treated for sterilization or oxidation by calculating the required amount of the acid to be mixed in the above aqueous solution to be injected in the water by a simple and easy method without being based on an actual measurement.SOLUTION: A controller 40 calculates a prescribed injection amount per unit time of sodium hypochlorite for sterilization or oxidation of the water to be treated from the measurement value of an instrumentation device 50 measuring the water to be treated, and further calculates the production requirement amount per unit time of the acid for adjusting to a prescribed pH value or a Langelier's index based on the above prescribed injection amount and the alkali component of the sodium hypochlorite. Then, the diluted aqueous solution of sodium hypochlorite is generated by diluting the calculated amounts of the sodium hypochlorite and acid, and is injected in the water to be treated.

Description

  The present invention relates to a method for producing and injecting a sodium hypochlorite diluted aqueous solution in which a sodium hypochlorite diluted aqueous solution produced containing sodium hypochlorite, an acid and diluted water is injected into water to be treated.

  When sodium hypochlorite is injected into the water to be treated for disinfection or oxidation as an undiluted solution, the oxygen gas generated by the self-decomposition of sodium hypochlorite is air-locked, particularly at the joints of the injection pipe, reducing the injection volume There was a problem that injection failure such as injection occurred. In addition, when sodium hypochlorite is injected into the water to be treated as a stock solution, the amount of sodium hypochlorite is very small relative to the amount of water to be treated. It was.

  As a method for preventing the above-described problems, there is a method in which sodium hypochlorite diluted aqueous solution generated by diluting sodium hypochlorite with diluted water such as purified water is injected into the water to be treated. FIG. 4 shows the dilute sodium hypochlorite by mixing the undiluted sodium hypochlorite and diluting water of the stock solution flowed from the storage tank 101 with the injector 103 under control of the injection controller 105, The production | generation injection | pouring method which inject | pours the produced | generated sodium hypochlorite diluted aqueous solution to process target water is shown. Further, FIG. 5 shows that dilute sodium hypochlorite by injecting sodium hypochlorite of the stock solution transported by the injection pump 102 from the storage tank 101 into the dilution water transport pipe 104 in which the dilution water is transported. The production | generation injection | pouring method which inject | pours the produced | generated sodium hypochlorite diluted aqueous solution to process target water is shown.

As for the above-described method for producing and injecting the sodium hypochlorite diluted aqueous solution, the hardness component (calcium, magnesium) in the diluted water and the alkali component in sodium hypochlorite react with each other, and the calcium scale ( Calcium carbonate) and magnesium scale (magnesium carbonate) are produced in the dilute aqueous solution of sodium hypochlorite and adhere to the inner surface of the injector and piping. .

Ca (HCO ₃ ) ₂ (hardness component) +2 NaOH (alkali component in sodium hypochlorite) → CaCO ₃ (calcium scale) + Na ₂ CO ₃ + 2H ₂ O
Mg (HCO ₃ ) ₂ (hardness component) +2 NaOH (alkali component in sodium hypochlorite) → MgCO ₃ (magnesium scale) + Na ₂ CO ₃ + 2H ₂ O

  As a method for suppressing scale formation in a dilute aqueous solution of sodium hypochlorite, it is a common practice to increase the dilution rate by increasing the amount of diluting water to an extremely high level relative to sodium hypochlorite. As shown in FIG. 6, in order to reduce the scale deposition rate to 5% or less, 200 times or more of dilution water is required with respect to the amount of sodium hypochlorite injected. There was a problem that maintenance costs would increase.

  As another method of suppressing the scale formation in another dilute aqueous solution of sodium hypochlorite, as shown in FIG. 7, in the water softening device 110 using an ion exchange resin, the hardness component that is the main component of the scale is obtained from the diluted water. The removed soft water is circulated through the dilution water transport pipe 104, and the raw solution sodium hypochlorite transported from the storage tank 101 by the injection pump 102 is injected to dilute, and the resulting sodium hypochlorite diluted aqueous solution is generated. There is a production injection method for injecting water into the water to be treated. Although scale generation is greatly suppressed, the ion exchange resin used in the water softening device 110 needs to be frequently regenerated using saturated saline in the resin regenerating device 111. There were problems such as an increase in equipment costs for the apparatus 111 and the like, and an increase in maintenance costs for performing complicated maintenance on these equipments.

  Further, in Patent Document 1 below, in a sodium hypochlorite diluted aqueous solution produced by diluting an acid and sodium hypochlorite with diluted water, hypochlorous acid having high sterilizing power is contained in the sodium hypochlorite diluted aqueous solution. In order to contain chloric acid at a high concentration, the supply amount of sodium hypochlorite and acid is controlled based on the pH value of the sodium hypochlorite diluted aqueous solution measured by the pH measuring means, and the sodium hypochlorite diluted aqueous solution It has been proposed to adjust the pH value around pH 5. Scale generation is suppressed by setting the pH value of the dilute aqueous sodium hypochlorite solution to pH 7 or less, but there is a problem that the equipment cost and the maintenance cost increase because measuring instruments such as pH measuring means are used. Furthermore, the amount of acid used is increased to bring the pH value of the diluted sodium hypochlorite aqueous solution produced by mixing acid with sodium hypochlorite, which is an alkaline solution, to around pH 5, and the pH is around 5. As a result, there was a problem that dangerous chlorine gas was generated.

  Furthermore, in Patent Document 2 below, the Langelia index, which indicates the degree of calcium scale generation, takes advantage of the possibility of scale generation when the index value is a positive value from 0, and the acid measured by the pH measuring means is Calculate the Langeria index from the pH value of the mixed sodium hypochlorite diluted aqueous solution, and soften the sodium hypochlorite diluted aqueous solution using a water softener when the calculated Langelia index is a positive value, Alternatively, it has been proposed that a scale dispersant is injected into a dilute aqueous solution of sodium hypochlorite to suppress scale formation. However, measuring equipment for measuring the pH value of dilute aqueous sodium hypochlorite solution and a water softening device for softening the diluted water are required, which increases equipment costs and maintenance costs, or scale dispersion. Since the agent is injected, there are problems such as mixing inappropriate chemicals as drinking water.

JP2010-162476 JP 2008-149226 A

  The present invention has been made to solve the above-mentioned problems, and the purpose of the present invention is to treat a sodium hypochlorite diluted aqueous solution produced by mixing an acid for suppressing scale formation. In the method of injecting sodium hypochlorite diluted aqueous solution injected into the target water for disinfection or oxidation, the required amount of acid mixed in the sodium hypochlorite diluted aqueous solution injected into the water to be treated is based on the actual measurement value It is providing the production | generation injection | pouring method of the sodium hypochlorite diluted aqueous solution which can be calculated by a simple method without it.

  Another object is to provide a method for producing and injecting a sodium hypochlorite diluted aqueous solution that can produce a sodium hypochlorite diluted aqueous solution without considering the amount and quality of the diluted water.

  In order to achieve the above object, a method for producing and injecting a sodium hypochlorite diluted aqueous solution according to the present invention is a treatment target for a sodium hypochlorite diluted aqueous solution produced containing sodium hypochlorite, an acid and diluted water. In the method for producing and injecting a sodium hypochlorite diluted aqueous solution to be injected into water, the control device receives a measurement value from an instrument that measures the treatment target water, and adds the measurement value to the treatment target water based on the measurement value. Calculate a predetermined injection amount per unit time of sodium hypochlorite to be injected, and a predetermined pH value based on the predetermined injection amount of sodium hypochlorite and the alkali components contained in the sodium hypochlorite Alternatively, the calculation required amount per unit time of the acid required for adjusting to the Langeria index is calculated, and the predetermined injection amount of sodium hypochlorite and the calculation required amount of acid are calculated. Diluting with a preset amount of dilution water per unit time set in advance to generate a sodium hypochlorite diluted aqueous solution, and injecting the generated sodium hypochlorite diluted aqueous solution into the water to be treated It is characterized by.

  The method for producing a diluted aqueous solution of sodium hypochlorite according to claim 2 of the present invention is the method for producing and injecting the diluted aqueous solution of sodium hypochlorite according to claim 1, wherein the predetermined pH value or Langeria index is The pH value is 9.6 or less, and the Langeria index is 2.2 or less.

  Moreover, the production | generation injection method of the sodium hypochlorite dilution aqueous solution which concerns on Claim 3 of this invention is the production | generation injection method of the sodium hypochlorite dilution aqueous solution of Claim 1 or 2, The said acid is a sulfuric acid, It is one of hydrochloric acid and carbonic acid.

  According to the method for producing and injecting a sodium hypochlorite diluted aqueous solution of the present invention having the above-described configuration, the required amount of acid for which scale production is suppressed is determined by the control device from the instrumentation instrument that measures the water to be treated. The measurement value is received, and based on the measurement value, a predetermined injection amount per unit time of sodium hypochlorite required for disinfecting or oxidizing the water to be treated is calculated. Unit time of the acid required to adjust the sodium hypochlorite diluted aqueous solution to a predetermined pH value or Langeria index based on the predetermined injection amount and the alkali component contained in the sodium hypochlorite Since the required amount per unit of calculation is calculated, it is possible to prevent excessive injection of acid and to prevent the pH value of the dilute aqueous sodium hypochlorite solution from being significantly lowered. It is possible to prevent the occurrence, it is possible to reduce the amount of acid used.

  According to the method for producing and injecting a sodium hypochlorite diluted aqueous solution of the present invention having the above-described configuration, the required amount of acid for which scale production is suppressed is determined by the control device from the instrumentation instrument that measures the water to be treated. The measurement value is received, and based on the measurement value, a predetermined injection amount per unit time of sodium hypochlorite required for disinfecting or oxidizing the water to be treated is calculated. Unit time of the acid required to adjust the sodium hypochlorite diluted aqueous solution to a predetermined pH value or Langeria index based on the predetermined injection amount and the alkali component contained in the sodium hypochlorite Since the calculation amount per unit is calculated, a water quality meter such as a pH meter or an electric conductivity meter that measures the pH value of the diluted sodium hypochlorite aqueous solution is not necessary, and the construction cost can be reduced. Rutotomoni, maintenance of calibration, etc. of the water meter for measuring the pH value of the dilute sodium hypochlorite solution can be reduced maintenance costs become unnecessary.

  Furthermore, since the control device calculates the predetermined injection amount of sodium hypochlorite and the required amount of acid with the preset amount of dilution water per unit time, the sodium hypochlorite Even if the predetermined injection amount per unit time fluctuates, the dilution water is constant when the preset amount per unit time is not changed, so that the generation work can be simplified. Further, since it is not diluted with a large amount of dilution water, the amount of dilution water can be reduced, and the dilution water supply facility can be made compact. Furthermore, since the proportion of the alkali component in sodium hypochlorite is much larger than the alkali component in the diluted water, there is no need to consider whether the quality of the diluted water is hard or soft water. A device can be dispensed with.

  Furthermore, since the predetermined pH value at which scale formation is suppressed in dilute aqueous sodium hypochlorite solution is set to pH 9.6 or less, or the Langeria index is set to 2.2 or less, the required amount of acid calculation is further reduced. In addition, it is possible to prevent generation of dangerous chlorine gas by setting the pH to 7 or more.

  Furthermore, since any of sulfuric acid, hydrochloric acid, and carbonic acid can be used as the acid to be injected, the acid to be used can be arbitrarily selected according to cost, water quality, and application.

Schematic explanatory diagram of the production and injection method of dilute aqueous sodium hypochlorite solution according to the present invention Graph showing the relationship between scale deposition rate and pH value or Langeria index Schematic explanatory drawing of the production injection method of another sodium hypochlorite diluted aqueous solution according to the present invention Schematic explanatory diagram of the conventional method for producing and injecting dilute aqueous sodium hypochlorite solution Schematic explanatory diagram of the conventional method for producing and injecting dilute aqueous sodium hypochlorite solution Graph showing the relationship between scale deposition rate and sodium hypochlorite dilution factor Schematic explanatory diagram of the conventional method for producing and injecting dilute aqueous sodium hypochlorite solution 3

  Hereinafter, with reference to the drawings, a method for producing and injecting a sodium hypochlorite diluted aqueous solution according to the present invention will be described by way of example.

Example 1
FIG. 1 is a schematic explanatory view showing a method for producing and injecting a sodium hypochlorite diluted aqueous solution according to the first aspect of the present invention.

  In the figure, 10 is a sodium hypochlorite storage tank for storing sodium hypochlorite as a stock solution. The stock sodium hypochlorite flows from the sodium hypochlorite storage tank 10 via the sodium hypochlorite transport pipe 11 to the diluting water transport pipe 20 described later at the injection point 21 by the injection pump 12 and mixed. Is done. The injection amount of sodium hypochlorite is a predetermined injection amount per unit time required to disinfect or oxidize the water to be treated, and is an instrument that will be described later in response to changes in the quality of the water to be treated. Based on the measurement value measured at 50, it is calculated by the control device 40 described later.

  Dilution water, such as purified water mixed with acid, is always circulated through the dilution water transport pipe 20 evenly at a preset amount per unit time. The quality of the dilution water may be hard water or soft water. The set amount per unit time of dilution water is controlled to take into account the size of the water treatment facility and the amount of water that can be used. It is set in advance by the device 40.

  30 is an acid storage tank for storing acid. The acid flows from the acid storage tank 30 through the acid transport pipe 31 by the acid injection pump 32 and flows into the diluting water that is constantly flowing evenly at the injection point 22 to be mixed. The acid injection amount is a calculation required amount per unit time required for preventing the scale from being generated in the diluted sodium hypochlorite aqueous solution, and is calculated by the control device 40. As the type of acid, one of sulfuric acid, hydrochloric acid, and carbonic acid is selected in consideration of the quality of the water to be treated.

  The control device 40 receives measurement values of the instrumentation instrument 50 that measures the treatment target water at regular intervals, and is a unit of sodium hypochlorite necessary for disinfecting or oxidizing the treatment target water based on the measurement values. Calculate the prescribed injection volume per hour. Furthermore, the control device 40 sets the unit per unit time based on the calculated predetermined injection amount of sodium hypochlorite per unit time and the known alkaline component contained in the sodium hypochlorite. When diluted with an amount of dilution water, the pH value of the sodium hypochlorite diluted aqueous solution, which is a level at which scale formation is suppressed in the sodium hypochlorite diluted aqueous solution, becomes pH 9.6 or less, or the Langeria index The required amount of acid to be injected per unit time is calculated so that is an index of 2.2 or less.

  50 is an instrumentation device that measures water to be treated. There are two types of target water to be measured by the instrumentation device 50: the target water before the sodium hypochlorite diluted aqueous solution is injected and the target water after the sodium hypochlorite diluted aqueous solution is injected. There is. Accordingly, the instrumentation device 50 may be installed in either one of the treatment target waters or in both of the two types of treatment target waters depending on the treatment target waters having different water quality. Specific measurement items measured by the instrumentation device 50 are individually determined for each water to be treated having different water quality.

  An example is described below. The control device 40 receives the measured value of the processing target water measured by the instrumentation device 50. The control device 40 calculates a predetermined injection amount per unit time of sodium hypochlorite necessary for disinfecting or oxidizing the water to be treated based on the received measurement value, and also calculates the next injection amount per unit time. Based on the prescribed injection amount of sodium chlorite and the known alkaline components contained in the sodium hypochlorite, dilute with sodium hypochlorite when diluted with a set amount of dilution water per unit time. Injection per unit time so that the pH value of the dilute sodium hypochlorite solution, which is a level at which scale formation is suppressed in the solution, becomes pH 9.6 or less, or the Langeria index becomes index 2.2 or less Calculate the required amount of acid to be calculated. The required amount of acid calculated per unit time calculated by the control device 40 is injected and mixed into dilution water that is distributed in an equal amount at a preset amount per unit time, and the diluted water is mixed with acid. Is distributed in an equal amount through the dilution water transport pipe 20 at a set amount per unit time set in advance, and a predetermined amount of injection per unit time calculated by the control device 40 is passed through the dilution water transport pipe 20. Sodium chlorite is injected and mixed to produce a diluted aqueous solution of sodium hypochlorite, and the generated diluted aqueous solution of sodium hypochlorite is injected into the water to be treated.

  After the injection of dilute aqueous sodium hypochlorite solution, the flow rate, water quality, etc. are measured by the instrumentation device 50 for the water to be treated when adjustment to the target value for the effect of disinfection or oxidation is required. The value is sent to the control device 40. On the other hand, the measurement values such as the flow rate and water quality measured by the instrumentation device 50 are sent to the control device 40 for the water to be treated before the sodium hypochlorite diluted aqueous solution is injected. Based on the measured value of the treatment target water after the sodium hypochlorite diluted aqueous solution is injected and the measured value of the treatment target water before the sodium hypochlorite diluted aqueous solution is injected, the control device 40 Calculate the predetermined injection amount of sodium chlorite and the required amount of acid. Therefore, in this case, the processes are sequentially repeated.

  In addition, as a method of controlling the predetermined injection amount of sodium hypochlorite and the calculation required amount of acid, a method of measuring and controlling water to be treated before the sodium hypochlorite diluted aqueous solution is injected, hypochlorite Method of measuring and controlling the water to be treated after the sodium hydroxide diluted aqueous solution has been injected, after the water to be treated and the sodium hypochlorite diluted aqueous solution being injected before the sodium hypochlorite diluted aqueous solution is injected There is a method to measure and control both of the treatment target water, and in consideration of the water quality of the treatment target water and the allowable level for the target value of the disinfection or oxidation effect on the treatment target water, any method is used to control Select

  In addition, as shown in FIG. 2, when calculating the injection amount of the acid at the above pH value, the scale deposition rate is 10% or less when the pH is 9.6 or less. However, when the pH is 9.3 or less, the scale deposition rate is Since it is 5% or less, it is more preferable to calculate the required amount of the acid to be injected so that the pH value of the diluted sodium hypochlorite aqueous solution is 9.3 or less. Note that when the pH value is decreased, the scale deposition rate gradually decreases. However, in consideration of a decrease in the amount of acid used and a decrease in the risk of generation of chlorine gas, the pH value is preferably set to pH 7 or more.

  Similarly, as shown in FIG. 2, when calculating the amount of acid injected with the Langerian index, the scale deposition rate is 10% or less when the index is 2.2 or less, but the scale deposition rate is 10 or less when the index is 1.8 or less. Therefore, it is more preferable to calculate the required amount of the acid to be injected so that the Langelia index of the diluted sodium hypochlorite aqueous solution is an index of 1.8 or less. Although the scale deposition rate gradually decreases when the Langeria index is reduced, the Langeria index is preferably set to an index of 0 or more in consideration of the decrease in the amount of acid used and the risk of chlorine gas generation.

  As described above, the required amount of acid to be injected and mixed into the diluted sodium hypochlorite aqueous solution is based on the measurement value of the instrument 50 that measures the flow rate, water quality, and the like of the water to be treated, calculated by the control device 40. Calculated by the controller 40 based on the predetermined injection amount per unit time of sodium hypochlorite necessary for disinfecting or oxidizing the water to be treated and the alkali components contained in the sodium hypochlorite. Therefore, it is possible to prevent dangerous chlorine gas from being generated due to a marked decrease in the pH value of the diluted sodium hypochlorite aqueous solution due to excessive injection of acid. Moreover, it becomes possible to suppress the usage-amount of an acid.

  Furthermore, the required amount of acid to be injected and mixed into the dilute aqueous sodium hypochlorite solution is to be treated based on the measurement values of the instrumentation instrument 50 that measures the flow rate and quality of the treatment target water calculated by the control device 40. Calculation calculated by the control device 40 based on a predetermined injection amount per unit time of sodium hypochlorite necessary for disinfecting or oxidizing water and an alkali component contained in the sodium hypochlorite Because it is a necessary amount, it becomes possible to eliminate the need for water quality instruments such as a pH meter and an electrical conductivity meter that measure dilute aqueous sodium hypochlorite solutions, and the construction cost and maintenance of dilute sodium hypochlorite transport equipment Management costs can be reduced, and maintenance work such as calibration of water quality meters can be facilitated.

  In addition, the required amount of acid to be injected and mixed into the diluted sodium hypochlorite aqueous solution is a treatment target based on the measurement value of the instrument 50 that measures the flow rate, water quality, etc. of the treatment target water calculated by the control device 40. Calculation calculated by the control device 40 based on a predetermined injection amount per unit time of sodium hypochlorite necessary for disinfecting or oxidizing water and an alkali component contained in the sodium hypochlorite This is a necessary amount, and the proportion of the alkali component in sodium hypochlorite is much larger than the alkali component in the diluted water. It becomes unnecessary to change, and it becomes possible to eliminate the need for complicated adjustment to change the amount of acid injection according to the water quality that is different for each site unique to the water treatment facility. In addition, since the dilution rate is not taken into consideration, it is possible to eliminate the need to change the dilution water amount each time in accordance with the predetermined injection amount of sodium hypochlorite.

  Moreover, the injection amount of the acid mixed with the sodium hypochlorite diluted aqueous solution is the water to be treated based on the measurement values of the instrumentation instrument 50 that measures the flow rate, water quality, etc. of the water to be treated, calculated by the control device 40. In a dilute aqueous solution of sodium hypochlorite based on the predetermined injection amount per unit time of sodium hypochlorite necessary to disinfect or oxidize and the alkali components contained in the sodium hypochlorite Since it is calculated by the control device 40 as a required calculation amount per unit time of the acid required for adjusting to a predetermined pH value or Langeria index at which scale generation is suppressed, dilution of dilute aqueous sodium hypochlorite solution Scale generation can be suppressed even if the magnification is lowered, and the dilution water supply facility can be made smaller. The construction cost and maintenance cost of the sodium hypochlorite dilution transport facility It is possible to reduce.

  Since the acid to be injected for adjusting the pH value and the Langeria index can be selected from sulfuric acid, hydrochloric acid, and carbonic acid, it is possible to arbitrarily select an acid to be used according to cost, water quality, and application.

Example 2:
FIG. 3 is a schematic explanatory diagram illustrating a method for producing and injecting a sodium hypochlorite diluted aqueous solution according to the second aspect of the present invention. The same numbers as those in the first embodiment indicate the same configurations. Hereinafter, differences from the first embodiment will be mainly described.

  In the figure, 10 is a sodium hypochlorite storage tank for storing sodium hypochlorite as a stock solution. The stock sodium hypochlorite flows out of the sodium hypochlorite storage tank 10 by water pressure, the flow rate is adjusted by the injection control device 13 installed in the sodium hypochlorite transport pipe 11, and an injector 23 described later. Flow into.

  The injector 23 includes diluted water such as purified water mixed with acid that always flows in a set amount per unit time that is set in advance, and hypochlorite that flows from the sodium hypochlorite storage tank 10 described above. Sodium hypochlorite is mixed under reduced pressure to dilute sodium hypochlorite to produce a dilute aqueous solution of sodium hypochlorite.

  An example is described below. The control device 40 receives the measured value of the processing target water measured by the instrumentation device 50. The control device 40 calculates a predetermined injection amount per unit time of sodium hypochlorite necessary for disinfecting or oxidizing the water to be treated based on the received measurement value, and also calculates the next injection amount per unit time. Based on the prescribed injection amount of sodium chlorite and the known alkaline components contained in the sodium hypochlorite, dilute with sodium hypochlorite when diluted with a set amount of dilution water per unit time. Injection per unit time so that the pH value of the dilute sodium hypochlorite solution, which is a level at which scale formation is suppressed in the solution, becomes pH 9.6 or less, or the Langeria index becomes index 2.2 or less Calculate the required amount of acid to be calculated. The required amount of acid calculated per unit time calculated by the control device 40 is injected and mixed into the diluted water flowing in an equal amount at a preset amount per unit time, and then flows into the injector 23. A preset amount of dilution water per unit time mixed with an acid and a predetermined injection amount of sodium hypochlorite per unit time calculated by the control device 40 are mixed under reduced pressure, and hypochlorous acid is mixed. A sodium chlorate diluted aqueous solution is generated, and the generated sodium hypochlorite diluted aqueous solution is injected into the water to be treated.

  After the injection of dilute aqueous sodium hypochlorite solution, the flow rate, water quality, etc. are measured by the instrumentation device 50 for the water to be treated when adjustment to the target value for the effect of disinfection or oxidation is required. The value is sent to the control device 40. On the other hand, the measurement values such as the flow rate and water quality measured by the instrumentation device 50 are sent to the control device 40 for the water to be treated before the sodium hypochlorite diluted aqueous solution is injected. Based on the measured value of the treatment target water after the sodium hypochlorite diluted aqueous solution is injected and the measured value of the treatment target water before the sodium hypochlorite diluted aqueous solution is injected, the control device 40 Calculate the predetermined injection amount of sodium chlorite and the required amount of acid. Therefore, in this case, the processes are sequentially repeated.

  In the description of the above-described embodiment, after injecting and mixing the acid into the dilution water, the original sodium hypochlorite was injected and mixed, but conversely after the original sodium hypochlorite was injected and mixed into the dilution water, Needless to say, the acid may be injected and mixed.

10 Sodium hypochlorite storage tank 11 Sodium hypochlorite transport pipe 12 Infusion pump
DESCRIPTION OF SYMBOLS 13 Injection control apparatus 20 Dilution water conveyance pipes 21, 22 Injection point 23 Injector 30 Acid storage tank 31 Acid conveyance pipe 32 Acid injection pump 40 Control apparatus 50 Instrumentation equipment

Claims (3)

In the method of injecting sodium hypochlorite diluted aqueous solution, injecting sodium hypochlorite diluted aqueous solution generated containing sodium hypochlorite, acid and diluted water into the water to be treated,
The control device receives a measurement value from an instrumentation device that measures the treatment target water, and calculates a predetermined injection amount per unit time of sodium hypochlorite to be injected into the treatment target water based on the measurement value And the unit time of the acid required to adjust to the predetermined pH value or Langerial index based on the predetermined injection amount of sodium hypochlorite and the alkali component contained in the sodium hypochlorite. Calculate the required amount per unit, dilute the prescribed injection amount of sodium hypochlorite and the required amount of acid with a preset amount of dilution water per unit time set in advance, and hypochlorous acid A method for producing and injecting a sodium hypochlorite diluted aqueous solution, wherein a sodium dilute aqueous solution is produced, and the produced sodium hypochlorite diluted aqueous solution is injected into the water to be treated.   2. The sodium hypochlorite diluted aqueous solution according to claim 1, wherein the predetermined pH value or the Langeria index is a pH value of 9.6 or less and the Langeria index is an index of 2.2 or less. Injection method. 3. The method for producing and injecting a diluted aqueous solution of sodium hypochlorite according to claim 1 or 2, wherein the acid is any one of sulfuric acid, hydrochloric acid, and carbonic acid.

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