JPH0656375B2 - Zirconia electrode and pH measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pH measuring device for measuring pH (pH) of a liquid at high temperature and high pressure, and more specifically,
The electrode for pH measurement is made of zirconia and gas can be supplied to the hollow part, and the liquid pressure in the internal space of the pressure vessel containing the solution is adjusted by the action of the pressure balancing means to the pressure of the gas in the hollow part of the zirconia electrode. To an improved pH measuring device so that the zirconia electrode can also withstand high hydraulic pressure.

(Prior Art and Problems Thereof) It may be necessary to measure pH in a liquid at high temperature and high pressure. For example, when investigating the corrosion phenomenon of a metal material in a solution under high temperature and high pressure. In this type of pH measuring device, the center is a pH measuring electrode, and as the electrode, a glass electrode, a zirconia (ZrO ₂ ) solid electrolyte diaphragm electrode, a Pt-H electrode, a Pd-H electrode, TiO ₂ semiconductor electrodes and the like are known. However, since each of them has advantages and disadvantages, a zirconia electrode is used when importance is attached to the stability of measurement.

The principle is briefly described. A zirconia electrode having a diaphragm made of zirconia and a reference electrode having a reference potential are set in a predetermined solution, and each is connected to a potentiometer. Then, if the type of solution, that is, the measurement atmosphere changes,
A potential corresponding to the hydrogen ion concentration is generated on the outer peripheral surface of the zirconia diaphragm, and a potential difference is generated between the reference electrode and the zirconia electrode in response to this, and this is measured by a potentiometer. It should be noted that the zirconia electrode is filled with a solid electrolyte or electrolytic solution, and oxygen is insufficient in the zirconia electrode during pH measurement, so it is necessary to replenish it from the outside.

Here, referring to the case where the conventional zirconia electrode is set in a high temperature and high pressure solution, the mechanical strength of the zirconia electrode becomes weak due to the high temperature and high pressure, and
Due to the high pressure, the zirconia diaphragm is easily deformed, and the amount of oxygen in the solid electrolyte or the electrolytic solution in the zirconia electrode may change, which may make continuous use difficult for a long time.

The present invention solves the above-mentioned problems, that is, a zirconia electrode having a zirconia diaphragm and capable of measuring the pH of a solution for a long time even when set in a high-temperature, high-pressure (particularly high-pressure) solution The purpose is to provide a pH measuring device.

Another object of the present invention is to achieve the above object by making the most of the components of a conventional measuring device without complicating the measuring device.

(Means and Actions for Solving Problems) In order to achieve the above object, the zirconia electrode (30) of the first aspect of the present invention is injected into a solution (16) in order to measure the pH of the solution. A hollow part (53) having a tip (55), at least the tip (55) being composed of a zirconia diaphragm (58),
The hollow portion (53) is configured to contain oxygen gas or a gas containing at least oxygen and to be supplied from the outside. The hollow portion (53) contains oxygen gas (which may be gas containing oxygen) instead of the conventional solid electrolyte or electrolytic solution, and this gas is supplied from the outside, so that the solid electrolyte or electrolytic solution Insufficient oxygen content in the liquid does not occur. Therefore, the electrode can be used for a long time.

Further, the second aspect of the present invention provides the zirconia electrode (30) for measuring the pH of the solution (16) in the pressure vessel (14), the reference electrode (20) injected into the solution, and the zirconia electrode ( A pH measuring device comprising a pH measuring means (22, 24) for measuring the pH value of the solution (16) from the potential difference between the electrode (30) and the reference electrode (20). As described above, the hollow part (53) of the zirconia electrode (30)
Since the oxygen gas is contained in and is supplied from the outside, the lack of oxygen which is a problem in the solid electrolyte and the electrolytic solution does not occur. Therefore, the pH of the solution in the pressure vessel can be measured for a long time.

The third aspect of the present invention provides a pressure vessel (1
The pH measuring device is equipped with a pressure balancing means (100) for balancing the pressure inside 4) and the gas pressure inside the hollow portion (53) of the zirconia electrode (30). The pressure of the gas in the hollow part (53) of the zirconia electrode (30) is adjusted by the pressure balance means (100) to the pressure vessel (14).
Since it is balanced with the internal pressure, the zirconia electrode is less likely to be deformed by the pressure in the pressure vessel, and the pH of the solution in the pressure vessel can be measured for a long time. This structure is particularly advantageous when the pressure of the pressure vessel is high.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In FIG. 1 showing the entire pH measuring device, a heater 1
A pressure vessel main body 14 is inserted into the hollow portion of the heating furnace 10 having 2 and is filled with a solution 16 of a predetermined type. The opening of the pressure vessel body 14 is covered with a pressure vessel cover plate 18, whereby the inside of the body is set in a sealed state. A reference electrode 20 and a zirconia electrode 30 having a zirconia diaphragm 58 for pH measurement are inserted through the pressure vessel cover plate 18, and the lower end of each (in the case of the zirconia electrode 30, the portion 55 in FIG. 3) is in the solution 16. And a potentiometer 22 is connected to the upper end. A pH measuring device 24 is connected to the potentiometer 22. The zirconia electrode 30 will be described in detail later.

A pressure balance adjuster 100 is arranged on the side of the pressure vessel body 14 and the cover plate 18, and one pressure that is balanced with each other is communicated with the vessel body 14 and the other pressure is communicated with the zirconia electrode 30. The pressure balance regulator 100 has a cylinder 160
Oxygen is supplied from the tank, which will be described later in detail.

Next, referring to FIG. 2, a zirconia electrode 3 for pH measurement
No. 0 will be described. The electrode 30 includes a cylindrical electrode holder 32, a cylindrical gas-filled pressure vessel 46 attached to an opening at one end thereof by a cap nut 70, and zirconia extending through a hollow portion of the holder. The zirconia diaphragm 58 is made hollow, including the diaphragm 58 and the like, and the hollow portion 53 is formed inside thereof.

That is, the electrode holder 32 is composed of a small diameter portion 34, a medium diameter portion 36 and a large diameter portion, and the small diameter portion 34 is screwed into a mounting hole 40 formed in the pressure vessel lid plate 18, and the medium diameter portion 36.
An annular water chamber 42 for filling cooling water is formed therein. The mounting portion 48 at the lower end of the gas filled pressure container 46 is inserted into the large diameter hole 44 of the large diameter portion 38, and the axial position is determined by the contact between the flange portion 50 and the end surface of the large diameter portion 38. A packing 52 seals between the mounting portion 48 and the large diameter portion 38.

The diameter of the hollow hole portion of the lower end portion 49 of the mounting portion 48 gradually increases toward the tip (lower end), and the head portion 56 formed at the upper end of the zirconia diaphragm 58 engages with this. The zirconia diaphragm 58 includes a body portion 54 and a head portion 56. The body portion 54 has a cylindrical tubular shape with a tip (lower end) in a crucible shape, and a head portion 56 is formed at the unend (upper end). Body 5
The platinum catalyst 60 is coated on the inner peripheral surface of the lower end portion of No. 4. The diameter of the head portion 56 is the lower end portion 49 of the mounting portion 48.
Is gradually reduced toward the tip (upper end) to engage with. The zirconia diaphragm 58 has a diaphragm fixing cap 6 on the neck.
1 is fitted, and the cap 61 is screwed to the lower end 49 of the mounting portion 48. As a result, the zirconia diaphragm 58 is fixed to the pressure container 46. A packing 64 seals between the head portion 56 and the lower end portion 49 of the mounting portion 48. And the electrode holder 32 and the pressure vessel 4
The peripheral portion 66 is screwed into the large diameter portion 38, and the flange portion 68 is integrated with the cap nut 6 by the cap nut 70 engaging with the end surface of the collar portion 50.

A large diameter hole 72 is formed at the upper end of the pressure vessel 46, and a radial direction 74 is formed at a portion slightly lower than the upper end, and communicates with the pressure chamber 76. An insulating seal plug 84 attached to a conductor insulating tube 82 holding a conductor 80 is seated on a step portion between the large diameter hole 72 and the pressure chamber 76, and a seal plug retainer 86 is further fitted. Seal plug retainer 8
6 and the cylindrical portion 88 are sealed by a packing 90, and the seal plug 84 and the presser 86 are provided in the cylindrical portion 8
It is fastened and fixed to the pressure vessel 46 by means of a cap nut 92 screwed onto the pressure vessel 8.

The insulating tube 82 extends substantially over the entire length of the pressure chamber 76 of the pressure vessel 46, and a coil 94 is connected to the end of the lead wire 80 held by the insulating tube 82.
It is in elastic contact with 0. The upper end of the conducting wire 80 is connected to the potentiometer 22 (FIG. 1). A gas introduction pipe 96 is fixedly installed in the radial hole 74.

The reference electrode 20 is a publicly known one, and the details thereof are described in, for example, Japanese Patent Publication No. 60-4130 filed by the applicant.
Please refer to 3.

Next, the pressure balance adjuster 100 will be described with reference to FIG. 3. The adjuster 100 includes a bottom plate 102, a main body 104, and
It consists of a pressure balancing piston 106 and a lid 108. A stepped hole 110 is formed in the center of the bottom plate 102, and a packing holder 109 is fitted and held therein. Body 104
Has a shape of a container opened downward, and a pressure balancing piston 106 is slidably fitted in the hollow portion of the main body 104.
A first pressure chamber 112 is formed above 06.
The first pressure chamber 112 has a communication hole 13 that forms a first passage.
1 and a pipe (gas introduction pipe) 96 communicate with the hollow portion 53 in the zirconia electrode 30. The piston 106 has an axial hole 114 and a radial hole 116. The cylindrical portion 120 of the main body and the piston 106 are sealed by double packings 122 and 124. A second pressure chamber 115 is provided below the piston 106.
Is formed in the pressure vessel 14 by the communication hole 133 and the pipe 97 that form the second passage.
Is in communication with.

A hollow minute differential pressure piston 126 is provided at the center of the lower surface of the pressure balancing piston 106, and the hollow hole 125 is communicated with the axial hole 114 to form a third passage.
The piston 126 is composed of an elongated hollow rod and is inserted into the hollow hole of the packing holder 110 to
6 and the holder 110 are sealed by a packing 129.

Large and small diameter axial holes 130 and 132 are continuously formed in the ceiling portion 128 of the main body 104, and a support portion 134 is continuously formed in the opening portion of the large diameter hole 132.
A support portion 134 is formed in the opening of 32. Hole 1
A first valve stem 136 is disposed within 30 and 132, and a valve portion 138 at the lower end can be inserted into the hole 114 of the piston 106, and is disposed between the collar portion 135 and the ceiling portion of the axial hole 130. The spring 140 is urged downward.

The lid 108 has large and small diameter axial holes 144 and 14
6 is formed, and the large diameter hole 144 communicates with the radial hole 148. From the small diameter hole 132 of the ceiling 128 to the lid plate 10
A second valve stem 150 is arranged over the eight holes 144 and 146. The valve rod 150 has a lower end that can come into contact with the first valve rod 36, and has a valve portion 152 at an intermediate portion,
A spring 156 is arranged between the upper spring receiving plate 154 and the end wall of the small diameter hole 146. Further, oxygen is supplied from the oxygen cylinder 160 to the radial hole 148 by a pipe 162.

Next, the operation and effect of this embodiment will be described.

The zirconia diaphragm 58 is a good conductor of oxygen ions, and the hydrogen ions in the solution 16 whose paper is to be measured react with oxygen ions to generate a membrane potential in the zirconia diaphragm 58. This membrane potential is measured by a potentiometer 22 via a coil and a lead wire, and compared with a reference potential of the reference electrode 20, and the paper measuring device 2
Converted to pH in 4 and displayed.

Oxygen in the zirconia diaphragm 58 is reduced by the above chemical reaction, and it is necessary to supplement oxygen there. Here, the pressure of the solution 16 in the pressure vessel 14 is P ₂ , and the pressure in the first pressure chamber 112 of the pressure balance adjuster 100 is P ₁
Then, assuming that the pressure of oxygen in the oxygen cylinder 160 is P ₃ , even if there is a difference between the pressures P ₁ and P ₂ , they are equalized by the action of the pressure balance adjuster 100.

That is, if the pressure P ₂ of the solution 16 in the pressure vessel 14 is P ₁
Higher than the second pressure chamber 1 through the pipe 97
15 pressure _{(P 2)} is, the pressure _{P 1} of the first pressure chamber 112
Therefore, the piston 106
Moves to the upper first pressure chamber 112 side. Then, the piston 106 lifts the first valve rod 136 with the valve portion 138 of the first valve rod 136 seated on the seat portion 139 at the upper end of the hole 114 of the piston 106 and closing the hole 114, and The upper end of the first valve rod 136 comes into contact with the lower end of the second valve rod 150, the second valve rod 150 is lifted upward, and the valve portion 152 separates from the seat portion 153 at the upper end of the axial hole 132. Therefore, the oxygen having the pressure P ₃ is supplied from the oxygen cylinder 160 through the pipe 162 to the pressure balance regulator 100.
Is supplied to the first pressure chamber 112. This supply of oxygen is performed until the pressure P ₁ of oxygen in the first pressure chamber 112 becomes equal to the pressure P ₂ of the solution 16 in the pressure vessel 14. Then, when the pressure P ₁ becomes substantially equal to P ₂ , the piston 106 descends and returns to its original position (FIG. 3), and the valve portion 152 is seated on the seat portion 153 to cut off the supply of oxygen.

On the contrary, when the pressure P ₂ inside the pressure vessel 14 becomes lower than P ₁ , the piston 106 is pushed downward due to the pressure difference between the upper and lower sides, and the valve portion 138 of the first valve rod 136 is inserted into the hole of the piston 106. The seat portion 139 at the upper end of 114 is separated. Then, the oxygen in the first pressure chamber 112 becomes
4 and the hollow hole 125, the pressure of the first pressure chamber 112 is reduced by being discharged to the outside. Then, the first pressure chamber 1
If the pressure P _{1 of} 12 becomes substantially equal to P ₂ , the piston 1
06 rises and returns to the original position (FIG. 3), and the valve portion 138
Seats on the seat portion 139 and stops the release of oxygen to the outside. Thus, the pressure P ₁ of the first pressure chamber 112, that is, the hollow portion 53 in the zirconia diaphragm 58, is the pressure of the second pressure chamber 115, that is, the pressure P ₂ of the solution 16 in the pressure vessel 14.
Is approximately equal to and is maintained in that state.

Further, in this embodiment, the pressure (P ₁ ) in the hollow portion 53 inside the zirconia diaphragm 58 is configured to be slightly lower than the pressure (P ₂ ) outside the hollow portion 53, that is, in the pressure vessel 14. This is because the zirconia electrode always receives a pressure on its outer surface, and a compressive stress is internally generated against it. Therefore, the differential pressure piston 12
6 is provided, the area of the piston 106 on the second pressure chamber 115 side is smaller than the area of the first pressure chamber 112 side by the outer diameter d of the differential pressure piston 126 ( (Fig. 3). Therefore, when the piston 106 is in equilibrium between the first and second pressure chambers 112 and 115, the pressure P ₂ of the second pressure chamber 115 is equal to the pressure P ₂ of the first pressure chamber 112.
Than _1, it increased by an amount to compensate for the force corresponding to the area of the outer diameter d of the differential pressure piston 126, between the pressure P ₁ of the first pressure chamber 112 and the pressure P ₂ of the second pressure chamber 115 Causes a slight pressure difference corresponding to the area of the outer diameter d. By appropriately selecting the size of the diameter of the differential pressure piston 126,
The magnitude of the vertical force acting on the piston 106 can be adjusted.

The pressure balance adjuster 100 includes pressure chambers 112 on both upper and lower sides.
Gases and liquids having completely different properties, such as gas and liquid, are enclosed in 115 and 115. However, since the packings 122 and 124 are doubly interposed, there is almost no risk of gas and liquid mixing. If even a small amount of gas or liquid leaks, it will be discharged to the outside through the hole 116 and the hollow portion of the differential pressure piston 126.

The present invention should not be construed as being limited to the above-mentioned examples, and appropriately changed within a range not impairing the gist thereof,
It goes without saying that improvements are possible. For example, the detailed structure of the zirconia electrode and the pressure balancing means, and the types of solution and gas can be selected as necessary.

As described above, according to the present invention, since the pressure of the solution in the pressure vessel and the pressure of the gas in the zirconia electrode can be balanced, even when the zirconia electrode is set in a high-pressure solution, This is not damaged, and the pH of the solution can be measured for a long time without any trouble.

[Brief description of drawings]

FIG. 1 is an overall view showing an embodiment of the present invention, FIG. 2 is a front sectional view showing its main part (zirconia electrode), and FIG. 3 is a front sectional view showing another main part (pressure balancer). Is. [Explanation of Signs of Main Parts] 10: Pressure Vessel 24: pH Measuring Device 20: Reference Electrode 22: Potentiometer 100: Pressure Balancer

Claims (4)

[Claims] 1. A hollow part having a tip injected into the solution for measuring the pH of the solution, wherein the tip is composed of a zirconia diaphragm, and oxygen gas or a gas containing at least oxygen is contained in the hollow part. A zirconia electrode characterized in that the gas is contained and the gas is supplied from the outside. 2. A hollow part having a tip which is injected into the solution for measuring the pH of the solution in the pressure vessel,
At least the tip is formed of a zirconia diaphragm, a zirconia electrode configured to contain oxygen gas or a gas containing at least oxygen in the hollow portion and the gas is supplied from the outside, and collation injected into the solution. A pH measuring apparatus comprising: an electrode; and a pH measuring unit that measures a pH value of the solution based on a potential difference between the zirconia electrode and the reference electrode. 3. A hollow portion having a tip which is injected into the solution for measuring the pH of the solution in the pressure vessel,
At least the tip is formed of a zirconia diaphragm, a zirconia electrode configured to contain oxygen gas or a gas containing at least oxygen in the hollow portion and the gas is supplied from the outside, and collation injected into the solution. An electrode, a pH measuring means for measuring the pH value of the solution from the potential difference between the zirconia electrode and the reference electrode, and a pressure balance for balancing the pressure in the pressure vessel and the gas pressure in the hollow portion of the zirconia electrode. And a pH measuring device. 4. The pH measuring device according to claim 3, wherein the pressure of the gas in the hollow portion of the zirconia electrode is slightly lower than the pressure in the pressure vessel to balance the pressure.