JPH0210148A - Composite electrode for measuring ph of high-temperature high-pressure aqueous solution - Google Patents

Abstract

PURPOSE:To obtain the composite electrode which is chemically stable and has a wide measurable temp. range and fast response speed by providing an oxide semiconductor sensing electrode part, a counter electrode part and a reference electrode part to the inside wall side of an insulating holder which is hollow and is open on one side. CONSTITUTION:Apertures 2-4 are provided to an insulating holder 1 and the oxide semiconductor pH sensing electrode 5 is held in the aperture 2 via an O-ring 7 in a cylinder 6 by positioning the electrode toward the inside wall side of the insulating holder. The reference electrode body 14 is fixed in the aperture 3 and a liquid permeable solid 15 is fixed to the inside wall surface side. An ion-permeable high-polymer film 16 is installed in the pipeline from the aperture 3 and an internal liquid 17 for the reference electrode is packed therein. Further, the counter electrode 28 made of an inert metal is held in the aperture 4 via an O-ring 20 in a cylinder 19 toward the inside wall side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite electrode for rapidly and accurately measuring the pH of a high-temperature aqueous solution (especially in a high-temperature, high-pressure environment).

[Prior Art] In general, the pH of an aqueous solution is determined by the reaction electrode portion consisting of a metal and a sparingly soluble salt or oxide of the metal formed on the surface of the metal, and the pH of the aqueous solution in an environment of normal temperature and pressure. The electrolyte is composed of an aqueous solution of an electrolyte containing a common anion, or an electrolyte that is an easily soluble hydroxide for the slightly soluble salt oxide, a container that isolates this aqueous electrolyte solution from the measurement target, and a liquid junction. ing. For example, in the high-temperature, high-pressure Yui environment p)l electrode, in addition to the harsh operating environment of high temperature and high pressure, it also contains substances that promote corrosion such as H2S, Co2, and C1- ions, so it is not suitable for the structure, material, and measurement. subject to restrictions. In order to avoid this restriction, attempts have been made to use Zr (h solid electrolyte diaphragm type electrode, Pt-l electrode, and Pd hydride electrode as measurement electrodes. However, in the presence of H2S, Co2., and C1- ions, However, due to reasons such as low stability and low measurement accuracy, the range of use is severely limited.

In addition, when measuring the pH of high-temperature water using the hydrogen electrode method, a test solution with a known dissolved hydrogen concentration is pressurized above the saturated vapor pressure to maintain a single phase liquid and circulated as high-temperature, high-pressure water. Measure the potential of the hydrogen electrode with respect to the reference electrode, convert it to the standard hydrogen electrode reference at each temperature, correct for the temperature change in hydrogen partial pressure, and divide the hydrogen electrode potential by the Nernst equation slope 2J/RT. pH due to
It is necessary to ask for Therefore, the biggest drawback of this method is that it is necessary to blow H2 into it, and it is difficult to accurately measure the H2 partial pressure with the current technology, and pH measurement by the hydrogen electrode method is almost never carried out. Furthermore, factors that make measurement difficult include the strength of the reducing action of H2 and the susceptibility to the influence of impurities (Redox type) in the solution.

Furthermore, the hydrogen electrode method has the limitation that when measuring the pH of high-temperature water using an actual device, it can only be applied if conditions such as the presence of dissolved oxygen and the absence of oxidizing substances are met. For this reason, attempts have been made to measure using the membrane electrode method. Although this membrane electrode is chemically stable, has a long life, and is unaffected by the Redox system in the solution, the main reasons are that the applicable temperature range is limited and the response speed is slow. This hinders practical measurements. Although JP-A No. 80-177257 discloses pH measurement at high temperatures, it is based on a photoelectrochemical method and is not suitable for pH measurement in oil well environments, which is the object of the present invention. It doesn't suit me. Furthermore, even if there is an electrode that can be used to measure pH in an oil well environment, it is impossible to measure pH with just the electrode alone; in some cases, a reference electrode that provides an electrode potential is required as a counter electrode for pH measurement. An active electrode is required.

[Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the drawbacks of the conventional p++ measurement method, and to develop a method for pH measurement that is chemically stable, has a wide measurable temperature range, and has a fast response speed. The object of the present invention is to provide a composite electrode. Furthermore, another object of the present invention is to provide a jig and a seal portion for safely holding the composite electrode for measurement in 9) 1 in a high-temperature, high-pressure oil well environment.

[Means for Solving the Problems] The gist of the present invention is as follows: (1) an oxide semiconductor sensing electrode portion disposed on the inner wall side of the insulating holder, which is partially hollow and has one side open; A counter electrode part made of an inert metal, a reference electrode part for regulating the potential of the sensing electrode from the outside, and each of the above electrode parts were connected to each other, and were buried through the solid part of the insulating holder. It is characterized by comprising a lead wire of 3 wood, a coupler for connecting the lead wire to a cable connected to a p) l measuring device, and a sealing part for insulating the connecting part from an external solution. Composite electrode for pH measurement of high temperature and high pressure water.

2. The sensing electrode part includes a cylinder electrically connected to the terminal at the end of the insulating holder, a sensing electrode arranged inside the cylinder toward the inner wall surface of the insulating holder, and fixing the sensing electrode. The composite electrode for measuring the pH of high-temperature, high-pressure water as described in item 1 above, comprising a presser foot and a plug for insulating the presser foot from the outside.

3. The reference electrode part has a liquid-permeable solid on the inner wall side of the boulder, an ion-permeable polymer membrane, an internal liquid separated from the liquid to be measured by the polymer membrane, and an internal liquid immersed in the internal liquid. The composite electrode for measuring pH of high-temperature, high-pressure water according to item 1 or 2 above, characterized in that it comprises a reference electrode body and a reference electrode body.

4 The counter electrode part includes a cylinder electrically connected to the terminal at the end of the insulating holder, a counter electrode placed inside the cylinder toward the inner wall surface of the insulating holder, and a presser for fixing the counter electrode. The composite electrode for measuring p++ of high-temperature, high-pressure water according to any one of the above items 1 to 3, characterized in that it is made of gold and a plug that insulates the presser foot from the outside.

It is in.

The present invention will be explained in detail below.

[Function and Examples] FIG. 1 shows an outline of a pH sensing composite electrode according to an example of the present invention. The insulating holder has a main body 1 provided with an opening 2 for holding a pH sensing electrode, an opening 3 for holding a reference electrode, and an opening 4 for holding a counter electrode. The main body 1 is made of mechanical strength such as polytetrafluoroethylene (hereinafter referred to as PTFE) resin, for example.
A chemically inert material with excellent electrical insulation properties is used.

FIG. 2 shows a cross section of the oxide semiconductor electrode in the opening for the pH sensing electrode.

A pH sensing electrode 5 is held in the opening 2 with its sensing surface facing the inner wall of the insulating holder in a stainless steel cylinder 6 via an O-ring 7, and a stainless steel presser 8. Electrical insulation from the outside is achieved by the ring 9 and the upper plug 10 made of PTFE. A small hole 11 is opened in the center of the thickness of the opening 2 toward one end of the insulating holder, and a vinyl plug is inserted into the hole for electrically connecting the stainless steel cylinder 6 and the external cable of the coupler part 12. Line 13 is embedded. This achieves electrical connection between the pH sensing electrode and an external cable. pH
As the sensing electrode, a TlO2 semiconductor electrode is preferable in consideration of chemical stability, usable temperature range, and response speed, such as in an oil well environment.

FIG. 3 shows a cross section of the reference electrode section.

In the opening 3, a liquid-permeable solid 15 is fixed to the inner wall surface of the insulating holder in order to establish electrical connection between the reference electrode body 14 and the liquid to be measured. An ion-permeable polymer membrane 16 is installed in the conduit provided from the opening 3 to one end of the insulating holder in order to prevent the liquid to be measured from mixing with the internal liquid for the reference electrode. A reference electrode internal liquid 17 is filled from the polymer membrane 16 toward one end of the insulating holder 1, and an electrical connection is achieved with the reference electrode body 14 whose one end is connected to one end of the insulating holder. ing.

One end of the reference electrode 14 is led out to the coupler portion 12 . The reference electrode is most preferably an Ag/AgCf1 electrode in consideration of physicochemical stability and usable temperature range, the liquid-permeable solid is preferably ZrCh, and the polymer membrane is most preferably a diaphragm.

FIG. 4 shows a cross section of the inert metal electrode in the counter electrode opening.

A counter electrode 18 is held in the opening 4 through an O-ring 20 in a stainless steel cylinder 19 toward the inner wall side of the insulating holder, and a stainless steel presser 21, an O-ring 22 and a PTFE upper part are attached. The plug 23 achieves electrical insulation from the outside. A small hole 24 is opened in the center of the wall thickness of the frontage part 4 toward the end of the insulating holder, and a vinyl wire 25 for electrically connecting the stainless steel cylinder and the coupler is embedded in the hole. There is. This achieves electrical connection between the counter electrode and the external cable.

For the opposite electrode, pt is most desirable from the viewpoint of chemical stability.

The pH sensing electrode 5 is attached to the solid end of the insulating holder.
, terminals for connecting the reference electrode 14 and the counter electrode 18 to external cables are provided. The terminal portion is provided with a coupler 12 to prevent electrical leakage due to infiltration of liquid from the outside. For the coupler, PTFE is most desirable in consideration of chemical stability and usable temperature range.

After measuring pH with the pH measurement composite electrode, the insulating holder can be disassembled for the purpose of cleaning the oxide semiconductor electrode part, the reference electrode part, and the counter electrode part, if necessary. be. Moreover, it can be said that the life of the composite electrode for pH measurement of the present invention is semi-permanent. Furthermore, the composite electrode of the present invention is easily portable and can be measured by lengthening the cable even when the solution to be measured is located several thousand meters underground, away from the measurement equipment, such as in an actual oil well environment.

Next, an example of the implementation of the example electrode will be described.

As a composite electrode for high temperature and high pressure oil well environmental pH measurement of the present invention,
The device shown in FIG. 1 was manufactured. This pH composite electrode is
%Na (4 in aqueous solution at 200 °C and 250 °C, CO
The samples were kept in an environment where the partial pressures of 2 and H2S were 10 and 40 atm, and the pH was measured. During measurement, an alternating current of 100 Hz was applied between the pH sensing electrode and the PT electrode, and T
The AC impedance of the iO2 semiconductor electrode and the phase difference between voltage and current were measured and converted to p)l.

Table 1 shows the results of measuring pH in the above environment. In any atmospheric gas, pressure, or temperature,
The values measured using the electrode according to the present invention were almost the same as the calculated values.

[Effects of the Invention] As described above, the composite electrode for measuring pH of high temperature water of the present invention has the following effects:
For example, it is possible to measure pH in Yui environment, which was previously considered impossible, and it is also reasonable from a scientific point of view.
This makes it possible to quantitatively evaluate high-temperature water in oil well environments, etc., and provides useful information for selecting and managing Yui materials, making it an extremely valuable tool that contributes to industrial development. be.

[Brief explanation of the drawing]

FIG. 1(a) shows a high-temperature, high-pressure oil well environment in an embodiment of the present invention.
Schematic diagram of H-sensing composite electrode, Fig. 1(b) is similar to Fig. 1(a)
A-A″ sectional view of , FIG. 2 is a sectional view of the po sensing electrode part,
FIG. 3 is a sectional view of the reference electrode part, FIG. 4 is a sectional view of the counter electrode part, and FIG. 5 is a sectional view of a part of the coupler. DESCRIPTION OF SYMBOLS 1... Insulating holder body, 23.4... Opening, 5... pH sensing electrode, 619... Stainless steel cylinder 7 9.20.22... O-ring, 821... Stainless steel presser, 10.23... Upper plug, 1124... Small hole, 12... Part of coupler, 13.25... Vinyl wire, 14... Reference electrode, 15... Liquid permeable solid, 16... Polymer membrane, 17... Internal liquid for reference electrode, 18... Counter electrode, 26... Piping.

Claims (1)

[Claims] 1. An insulating holder that is partially hollow and open on one side, an oxide semiconductor sensing electrode section disposed on the inner wall side of the insulating holder, a counter electrode section made of an inert metal, and a counter electrode section made of an inert metal. A reference electrode part for regulating the potential of the sensing electrode from the outside, three lead wires connected to each of the above electrode parts and embedded through the solid part of the insulating holder, and the lead wires. p
A composite electrode for measuring the pH of high-temperature, high-pressure water, comprising a coupler for connecting to a cable connected to an H measuring device, and a sealing part for insulating the connecting part from an external solution. 2. The sensing electrode part includes a cylinder electrically connected to the terminal at the end of the insulating holder, a sensing electrode arranged inside the cylinder toward the inner wall surface of the insulating holder, and fixing the sensing electrode. 2. The composite electrode for measuring pH of high-temperature, high-pressure water according to claim 1, comprising a presser foot and a plug for insulating the presser foot from the outside. 3. The reference electrode part has a liquid-permeable solid on the inner wall side of the holder, an ion-permeable polymer membrane, an internal liquid separated from the liquid to be measured by the polymer membrane, and an internal liquid immersed in the internal liquid. 3. The composite electrode for measuring pH of high-temperature, high-pressure water according to claim 1 or 2, comprising a reference electrode body. 4 The counter electrode part includes a cylinder electrically connected to the terminal at the end of the insulating holder, a counter electrode placed inside the cylinder toward the inner wall surface of the insulating holder, and a presser for fixing the counter electrode. The composite electrode for measuring the pH of high-temperature, high-pressure water according to any one of claims 1 to 3, comprising gold and a plug for insulating the presser foot from the outside.