JPH05253579A - Neutralization control device - Google Patents

Abstract

PURPOSE:To provide the title device automatically selecting a proper nutralization titration curve from the pH change rate due to the charging amount of a neutralizing agent and charging a proper amount of the neutralizing agent not only to shorten the time of a neutralization process but also to prevent the generation of unnecessary waste. CONSTITUTION:A neutralization control unit consists of an input processing part 3 inputting the pH value of a waste fluid to be neutralized, an output treatment part 4 outputting the charging amount of a neutralizing agent, a memory part 2 storing a neutralization titration curve group and an operational processing part 5 operating a pH change rate from the pH value inputted from the input processing part 3 and the charging amount of the neutralizing agent outputted from the output processing part 4 and comparing the same with the neutralization titration curve group of the memory part 2 to select a proper nutralization titration curve and determining the proper charging amount of the neutralizing agent to output the same to the output processing part 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutralization control device for controlling the neutralization reaction by determining the amount of the neutralizing agent added based on the pH value of the target liquid.

[0002]

BACKGROUND OF THE INVENTION Chemical waste liquids such as nuclear power plant waste liquids include regeneration waste liquids for condensate desalination equipment and decontamination waste liquids after equipment decontamination.
Since various liquids such as chemical waste liquid for water quality decomposition are included, to eliminate the corrosiveness of this liquid due to acidity and to facilitate waste liquid treatment, a nuclear power plant or chemical plant has a waste liquid neutralization facility. Is installed.

This neutralizing equipment is usually equipped with a neutralizing agent tank, a neutralizing agent charging pump, a waste liquid tank, a waste liquid stirring pump, and a pH.
It consists of a meter, piping and neutralization control device. Of these, the neutralization control device controls the amount of the neutralizing agent input by the neutralizing agent input pump according to the pH value of the waste liquid.

Here, if the chemical waste liquid is only one kind of acid, the amount of the neutralizing agent required for neutralization can be easily obtained from the method of neutralization titration performed in the laboratory and the tank capacity. , Chemical waste liquid contains several kinds of acids, bases and salts, and there is a buffer solution that has a buffering effect that suppresses the pH value change due to the addition of a neutralizing agent. Further, since the mixing ratio is not always the same, the amount of the neutralizing agent injection required until the completion of neutralization is not simply determined, which makes it difficult to control the neutralization of the chemical waste liquid.

For example, as shown in the neutralization titration curve group diagram of FIG. 3, the theory of neutralization titration of a strong acid with a strong base, where the vertical axis represents the amount of the neutralizer input v and the horizontal axis represents the pH value. Compare with curve 20,
In the case of a chemical waste liquid, the amount of the neutralizing agent required for neutralization increases due to the presence of the buffer solution, and the neutralization titration differs depending on the type of waste liquid as shown by curves 21 to 23.

Therefore, in the case of neutralizing the chemical waste liquid,
Although the type of waste liquid is unknown, excessive addition of a neutralizing agent causes the solution to become more basic, which increases the amount of neutralizing agent added until the completion of neutralization, resulting in an increase in waste. Therefore, the method of gradually adding the neutralizing agent while always measuring the pH value is adopted.

Examples of this neutralization process include (1) stirring / pH value measurement / neutralizing agent injection, (2) same operation as (1), (3) same operation as (1), (4) (1 )), And (5) stirring / pH value measurement (final determination) is usually repeated several times.

[0008]

In neutralizing chemical waste liquid,
Since the neutralization titration curve of the target waste liquid is unknown, it is difficult to determine the required amount of neutralizer input even if the pH value is known. Therefore, the amount of the neutralizing agent added in the neutralization step of the waste liquid can be selected as large or small depending on the pH value, but basically it is a trial and error method to gradually bring it to neutralization. , Generally, stirring /
It is necessary to repeat the steps of pH value measurement / neutralizing agent addition about 4 times. Therefore, there is a problem that it takes a long time to complete all the steps and even if the neutralizing agent is excessively added, the amount of waste increases.

[0009] This increase in waste causes an increase in the amount of radioactive waste, especially in a nuclear power plant, which causes an obstacle to the capacity of the treatment facility.

The object of the present invention is to automatically select an appropriate neutralization aptitude curve from the pH change rate depending on the amount of the neutralizing agent added, and to add an appropriate amount of the neutralizing agent, An object of the present invention is to provide a neutralization control device that saves time and prevents the generation of unnecessary waste.

[0011]

An input processing unit for inputting a pH value of a waste liquid to be neutralized, an output processing unit for outputting an input amount of a neutralizing agent, a storage unit for storing a neutralization titration curve group, and The pH change rate is calculated from the pH value input from the input processing section and the neutralizing agent input amount output from the output processing section, and the pH change rate is compared with the neutralization titration curve group in the storage section to obtain an appropriate value. A neutralization titration curve is selected and an arithmetic processing unit for determining an appropriate amount of the neutralizing agent input and outputting it to the output processing unit is characterized.

[0012]

[Operation] Based on the pH value of the waste liquid input from the input processing unit, the arithmetic processing unit puts in a predetermined amount of the neutralizing agent based on the pH value from the theoretical curve of the neutralization titration curve group stored in the storage unit in advance, After stirring, measure the pH value again. Next, the pH change relative to the amount of the neutralizing agent added, that is, the rate of pH change is determined, and the initial pH value and pH
The rate of change is compared with the neutralization titration curve group in the memory unit, and the closest neutralization titration curve is selected.

From the neutralization titration curve and the present pH value, the amount of the neutralizing agent required for the completion of the neutralization is determined, and the output processing unit instructs the input pump. After this neutralizing agent is added, the waste liquid is stirred again with a stirring pump to adjust the pH value to a specified value (for example, 7 ≦ pH
After confirming that ≦ 8), the neutralization control is completed.

[0014]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a neutralization control device and a neutralization device related thereto, and FIG. 2 is a group diagram of neutralization titration curves. The neutralization control device 1 stores several types of neutralization titration curves based on actual plant performance, a storage unit 2 for storing neutralization titration curves of strong acids and strong bases, that is, theoretical curves, and detected waste liquids.
An input processing unit 3 for inputting a pH value, an output processing unit 4 for outputting a neutralizer input amount, a pH value input from the input processing unit 3 and a neutralizer input amount output from the output processing unit 4. The pH change rate is calculated from the calculated pH change rate, and the pH change rate is stored in the storage unit 2
Of the neutralization titration curve group, a proper neutralization titration curve is selected, an appropriate amount of the neutralizing agent is determined, and the calculation processing section 5 outputs the output to the output processing section 4.

In FIG. 2, the vertical axis represents the amount of the neutralizing agent input v, and the horizontal axis represents the pH value. The theoretical curve 11 stored in the storage unit 2,
And neutralization titration curves 12, 13 based on actual plant performance
14 is shown. The neutralization device also detects, for example, a waste liquid tank 6 that stores and neutralizes waste liquid, a stirring pump 7 that pumps out the waste liquid in the waste liquid tank 6 and returns it to the waste liquid tank 6, and further detects the pH value of the waste liquid. The pH meter 8 and the neutralizer tank 9 that output the neutralization agent to the input processing unit 3 of the neutralization control device 1 and the waste liquid tank 6 by the command from the output processing unit 4 of the neutralization control device 1 It is composed of a neutralizing agent charging pump 10 to be charged, and pipings that connect the respective devices.

Next, the operation of the above configuration will be described. After the stirring pump 7 is operated to circulate and stir the waste liquid in the waste liquid tank 6, the input processing unit 3 of the neutralization control device 1 inputs the pH value detected by the pH meter 8. From this pH value, the arithmetic processing unit 5 obtains the neutralizing agent input amount Δv required on the theoretical curve 11 from the input pH value and the theoretical curve 11 stored in the storage unit 2. This neutralizing agent input amount Δv and the above
The pH value is stored in the storage unit 2.

The output processing unit 4 outputs an output signal corresponding to the neutralizing agent input amount Δv to the neutralizing agent input pump 10. The neutralizing agent input pump 10 inputs the neutralizing agent input amount Δv according to this command from the neutralizing agent tank 9 to the waste liquid tank 6. After that, the waste liquid in the waste liquid tank 6 is stirred by the stirring pump 7, and the pH value after the neutralizer is added is measured again by the pH meter 8.

The amount of the neutralizing agent added first is
There is no problem if the waste liquid does not become basic because it is too much, but the amount that does not hinder is unknown, but in order to improve work efficiency, it is better to add as much as possible. Therefore, as one guide, it is considered that it is preferable to use the neutralizing agent input amount Δv obtained from the theoretical curve 11.

Next, the arithmetic processing unit 5 calculates the pH change rate ΔpH / with respect to the neutralizing agent input amount Δv from the previous pH value and the neutralizing agent input amount Δv stored in the storage unit 2 and the pH value measured this time.
By determining Δv and comparing this and the previous pH value with the neutralization titration curves 12, 13, and 14 stored in the storage unit 2, it is possible to select which neutralization titration curve the wastewater neutralization titration curve is close to. To do.

For example, in FIG. 2, the initial pH value is pH 3, and the pH change after the addition of the neutralizing agent Δv is ΔpH.
If it is close to -2, select neutralization titration curve 13. Further, the arithmetic processing unit 3 obtains the neutralizing agent input amount va necessary for neutralization from the neutralization titration curve 13. The output processing unit 4 uses the neutralizing agent input amount v
An output signal corresponding to a is output to the neutralizer injection pump 10.

After a predetermined neutralizing agent is charged by the neutralizing agent charging pump 10, stirring is performed by the stirring pump 7 to measure the pH value again, and finally the judgment reference value, for example, pH 7 to pH 8 is entered. And the neutralization work is completed. In addition, in the above-mentioned one embodiment, the neutralization titration curve stored in the storage unit 2 is set to 3
Although described as a seed, by increasing the number of curves, a finer and more optimal neutralization titration curve can be easily selected, and more accurate neutralization control can be performed.

[0022]

As described above, according to the present invention, several acids, bases,
The process of stirring / pH value measurement / neutralizing agent addition required to complete the neutralization of the waste liquid mixed with salt, etc. is performed only twice, and an appropriate neutralizing titration curve can be selected and controlled. The effect is to minimize the input amount of. As a result, the time required to complete the neutralization of the waste liquid can be greatly shortened, and the amount of salt generated by the neutralization, that is, the amount of waste can be minimized. Particularly in the case of nuclear power plants, the effect of reducing radioactive waste is significant.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a neutralization control device and a neutralization device according to an embodiment of the present invention.

FIG. 2 is a group diagram of neutralization titration curves stored in a storage unit according to an embodiment of the present invention.

FIG. 3 is a group diagram of neutralization titration curves of general chemical waste liquid.

[Explanation of symbols]

1 ... Neutralization control device, 2 ... Storage unit, 3 ... Input processing unit, 4 ...
Output processing unit, 5 ... Arithmetic processing unit, 6 ... Waste liquid tank, 7 ... Agitation pump, 8 ... pH meter, 9 ... Neutralizer tank, 10 ... Injection pump.

Claims (1)

[Claims] 1. An input processing unit for inputting a pH value of a waste liquid to be neutralized, an output processing unit for outputting a neutralizer input amount, a storage unit for storing a neutralization titration curve group, and the input processing unit. An appropriate neutralization titration curve is calculated by calculating the pH change rate from the input pH value and the neutralizing agent input amount output from the output processing unit, and comparing the pH change rate with the neutralization titration curve group in the storage unit. The neutralization control device is characterized by comprising an arithmetic processing unit that selects the appropriate amount of neutralizer and outputs the determined neutralizing agent to the output processing unit.