JPS60125556A - Convection circulation type dissolved oxygen meter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a fixed concentration of dissolved 07 in reactor water in light water reactors, heavy water reactors, etc. 6 [Background of the Invention] Fig. 1 shows a known high-temperature, high-pressure dissolved The structure of an oxygen meter is shown. In this dissolved oxygen meter, a detector 13 is housed in a pressure-resistant container 14, and sample water introduced from a sample water inlet 16 is passed through a water hole 5 to immerse the entire detector in high-pressure sample water 15. 6 and the sample water to improve pressure resistance, the detector and oxygen permeable membrane 3 are made of heat-resistant resin, and the bellows 10 absorbs the thermal expansion of the electrolyte to improve heat resistance. It is characterized by improving sexual performance. To prevent the internal pressure of the detector from increasing due to the tension of the bellows and damaging the oxygen permeable membrane.

The oxygen permeable membrane is inserted and supported by a porous cathode 4 and a metal filter 1 to reinforce the oxygen permeable membrane. Dissolved 02 in sample water
passes through the metal filter and oxygen permeable membrane and enters the detector. The porous cathode is made of gold and the anode is made of silver. A KCQ solution is used as the electrolyte. The porous cathode is a constant voltage power supply 1
1, the dissolved O3 that has entered the detector is reduced to 0)(-) on the porous cathode according to equation (1).

0. +2H20+4 e--)40H-・=(1) On the other hand, on the anode, the reaction of formula (2) proceeds, and one bipolar Ag+CQ
A current flows between -→AgCQ+e−(2). This current is detected by an ammeter 10, and the dissolved 02 concentration is determined from this current value.

[Purpose of the invention]

The purpose of the present invention is to continuously supply an electrolytic solution from a large volume reservoir to the vicinity of the electrodes in the detector, thereby making it possible to quantify the dissolved 02 concentration in sample water at high temperature and high pressure over a long period of time. There is an oxygen meter to provide.

[Summary of the invention]

Since the known dissolved oxygen meter consumes CQ- ions in the electrolyte during 02 measurement, the usable time of the detector is limited by the total amount of CQ- ions, that is, the amount of the electrolyte. Therefore, in order to extend the usage time of a dissolved oxygen meter, it is essential to equip it with a large capacity reservoir and increase the amount of electrolyte. However, in known dissolved oxygen meters, it is difficult to create a temperature gradient that causes convection within the detector, and transport of CQ- ions is performed exclusively by diffusion, resulting in low transport efficiency and the ability to smoothly transport CQ-ions from the liquid reservoir to the vicinity of the detector. The problem was that ions were not transported. Therefore, in the present invention, by creating a temperature gradient between the detector and the liquid reservoir, the electrolyte is circulated by creating convection between the two, and the electrolyte is smoothly and continuously transferred from the liquid reservoir to the vicinity of the electrode. I thought about supplying it.

The features of the present invention include providing a large capacity reservoir filled with electrolyte above the detector and communicating with the electrolyte in the detector, and providing a temperature gradient such that the detector is at high m and the wjt reservoir is at low temperature, or By installing a large-capacity liquid reservoir at the bottom of the detector and creating a temperature gradient in which the detector is at a low temperature and the liquid reservoir is at a high temperature, convection is created between the liquid reservoir and the detector, and electrolysis occurs between the two. The purpose is to circulate the liquid and smoothly and continuously supply the electrolyte from the liquid reservoir to the vicinity of the electrode.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described using FIGS. 2 to 4. FIG. 2 is a schematic diagram of a convection circulation type dissolved oxygen meter. The convection circulation type dissolved oxygen meter includes a detector body 13, a liquid reservoir 22 connected thereto, and a body pressure vessel 14 that houses these.
, and a constant voltage power supply, 11. It consists of an external electric circuit system connected to the electrodes in the detector, such as a voltmeter 12 and an ammeter lo. An oxygen permeable membrane 3 is provided on the surface of the detector body, and an electrolytic solution 6 is sealed inside. A KCQ aqueous solution is used as the electrolyte. A porous cathode 6 and an anode 7 are arranged in this electrolyte. The porous cathode is made of gold, platinum, etc., and the anode is made of silver. The oxygen permeable membrane is reinforced by a porous cathode and a metal filter 1. 02 in the sample water passes through the metal filter and oxygen-permeable membrane and is reduced to OH- according to equation (1) on the porous cathode, and the reaction of equation (2) proceeds on the anode, causing a current to flow between the two electrodes. flows. This current is detected to quantify the dissolved zero and concentration. The detector has a liquid reservoir filled with the same electrolyte as the detector in tube A17 and tube B.
connected by 18. Electrolyte can be transferred between the detector and the reservoir through these tubes.

The tube, liquid reservoir, detector body, oxygen permeable membrane, etc. are made of tetrafluoroethylene resin.

Manufactured from heat-resistant resins such as fluorocarbon resins, silicone resins, and polyimide resins. The detectors are arranged at the bottom of the pressure-resistant container and at the top of the liquid reservoir pressure-resistant container, and these are fixed inside the container by a pedestal 2. High-pressure sample water is introduced into the container from a sample water inlet 16 at the bottom of the pressure container, and flows out from a sample water outlet 9 provided at the bottom of the same pressure container. A part of this sample water flows into the inner part of the pressure-resistant container through the water passage hole 5 provided in the pedestal, and the inside of the container is filled with the sample water. Since the detector, the tube, and the entire liquid reservoir are immersed in this sample water, a pressure balance is maintained between the sample water and the electrolyte, and these are not damaged by the sample water pressure. As the high-temperature water flows in, the temperature of the detector increases, so the thermal expansion of the electrolyte is absorbed by the bellows 8 provided in the reservoir. When the pressure-resistant container is filled with sample water, the inflow of sample water through the water hole is reduced, and the sample water injected from the sample water inlet circulates only at the bottom of the container and flows out as it is.
The lower part of the pressure vessel is heated to a high temperature. On the other hand, the upper part of the container is cooled by heat radiation, resulting in a temperature gradient in which the lower part of the container is at a higher temperature and the upper part is at a lower temperature.

Accordingly, a temperature gradient occurs in the electrolytic solution 4, with the liquid reservoir side being low temperature and the detector side being high temperature. This temperature gradient causes convection of the electrolyte, and the electrolyte in the detector rises from the pore B21 through the tube AL7 into the liquid reservoir and is cooled within the liquid reservoir. On the other hand, the electrolytic solution in the reservoir flows into the detector through the pore 19 through the tube B and is heated. A valve A20 and a valve B23 are attached to the pores A and B to prevent backflow of the electrolyte. This circulation of electrolyte based on convection allows the electrolyte to be continuously and efficiently supplied from the reservoir to the detector even when using a large-capacity reservoir, greatly improving the operating time of the detector. can be done. In this example, a KCQ aqueous solution was used as the electrolyte, but this may be other aqueous solutions such as H2SO, 504Na, SO2, etc., or an aqueous solution containing 5042- ions such as 11,1PO4,
Na112PO4, Nat HPO4, Na, PO4
It is also possible to use an aqueous solution containing Po, 2-ions such as. At this time, the anodic reaction is expressed by equation (3) and equation (4), respectively.
becomes.

2Ag+30.2--+Ag25Oa +2e--(3
)3Ag+P0.3-→Agi po4+3e--(4
) Also, if there is no need to limit the direction of circulation of the electrolytic solution, valves A and B are unnecessary.

In this embodiment, the upper part of the pressure vessel is cooled by natural heat radiation. As shown in FIG. 3, air cooling fins 24 may be provided at the upper part of the pressure vessel to cool the upper part of the pressure vessel. Further, as shown in FIG. 4, a cooling tank 25 may be attached to the upper part of the pressure vessel and cooling water 28 may be passed between a cooling water outlet 27 and a cooling water outlet 26 for cooling.

〔Effect of the invention〕

According to the present invention, a large amount of electrolyte can be continuously and efficiently supplied to the vicinity of the electrode, so that the usage time of the detector can be significantly extended. When applying a high-temperature, high-pressure dissolved oxygen meter to quantify the dissolved O2 concentration in sub-reactor cooling water,
It is essential that the device has the ability to be used continuously from one periodic inspection to the next periodic inspection without adding operations such as replenishing the electrolyte, and the present invention can provide an effective means for this purpose. .

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a known high-temperature, high-pressure dissolved oxygen meter;
The figure is a schematic diagram of a convection circulation type dissolved oxygen meter according to an embodiment of the present invention, and FIGS. 3 and 4 are sectional views showing modified examples of the container used in the convection circulation type dissolved oxygen meter. ■... Metal filter, 2 river pedestal, 3... Oxygen permeable membrane, 4... Porous cathode, Death... Water hole, 6... Electrolyte, 7... FJ)ll, 8 ...bellows, 9...
Sample water output 0.10... Current side, 11... Constant voltage power supply, 12... Voltmeter, 13... Detector body, 14...
・Pressure container, 15...sample water, 16...sample water inlet, 17...tube A, 18...tube B, ]9
...Pore A, 2o...Valve A, 21...Pore B, 2
2...Liquid reservoir, 23...Valve B, 24...Air cooling fin, 25...Empty tank, 26...Air cooling water outlet, 27...
...1st mouth 2nd figure 3 figure 4 figure 9

Claims (1)

[Claims] 1. A container is filled with an electrolytic solution, a diaphragm is placed on the surface of the container in contact with the sample water, a detector is provided with a working electrode and a counter electrode in the electrolytic solution, and wires are connected to both of the electrodes. In a diaphragm-type dissolved oxygen meter, which consists of an electric circuit system consisting of a power supply device that maintains a constant potential between both electrodes and an ammeter that measures the current flowing between both electrodes, the electrolyte in the detector A communicating large volume liquid reservoir is placed above the detector, and a temperature gradient is created so that this liquid reservoir is cooler than the detector.
A convection circulation dissolved oxygen meter characterized in that the electrolyte is circulated between the reservoir and the detector by convection, thereby smoothly and continuously supplying the electrolyte from the reservoir to the detector.