JPS6180041A - Device for detecting partial pressure of gas in environment in which abnormality is generated - Google Patents

Abstract

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

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to galvanic gas sensors, and more particularly to compensation networks for such sensors.

[Prior art]

Flow! Galvanic gas sensors and similar devices are well known in the art. U.S. Pat. No. 3,149,921 discloses a method for measuring the partial pressure of a reactant gas by arranging various conditions of the cell such that the electrical output of the cell is determined by the concentration of the reactant gas. The basic technology for employing fuel cells is described. The technology disclosed in this patent employs a number of techniques to generate electricity from fuel by utilizing reactant gases as fuel and oxygen.

An improved gas sensor is disclosed in US Pat. No. 3,616,411, issued to the inventor of the present invention. The gas introduced into the gas sensor and metered by passing through the diffusion barrier is ionized by contact with an absorbent catalyst in the presence of an electrolyte. This ionization represents the partial pressure of the gas.

Since such conventional sensors are typically used in environments that produce many anomalies, the output signal appearing across the terminals of the gas sensor not only represents the partial pressure of the detected gas, but also the components caused by the environment. Also included. therefore,
Gas sensors that compensate for abnormalities caused by their environment would be of great advantage in this field.

[Summary of the invention]

In the present invention, a compensator is provided which can be used to compensate for anomalies caused by the environment.

The compensator is placed in hydrogen gas and consists of a housing having a sensing electrode and a counter electrode.

A potential is created between the detection electrode and the counter electrode, which is indicative of the partial pressure of the gas whose constituents caused by environmental anomalies are to be detected.

A third electrode is provided inside the sensor. This third electrode is electrically isolated from the other two electrodes and isolated from the gas to be detected. The third electrode is connected to either the counter electrode or the sensing electrode such that the potential generated is the result of an environmentally induced anomaly. The signals from each electrode pair are connected to produce a signal difference so that the output is indicative of the partial pressure of the gas to be detected.

Another embodiment of the invention generates an output signal representative of the partial pressure of the gas to be detected when connected to a typical gas sensor as shown in the prior art.

In this embodiment, the electrodes are separated from the gas such that the compensator produces an emf that directly cancels the portion of the emf caused by the environment.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 and 2, electrolyte compensator 10 includes a cylindrical housing 12. In FIGS. This housing 12 is
It has a first end 14 and a second end 16. A threaded annular retainer 20 extends upwardly from the interior of the end portion 14.
It has an axial passage 22 and a lower end 23. Retainer 20
A cylindrical thin film holder 2B is juxtaposed to the end portion 23 of the cylindrical membrane holder 2B.

The membrane retainer 28 includes a shoulder 26, an upper end 30. and a lower end portion 34. When the retainer 20 is screwed in clockwise, the corrugated springs 24 are compressed, forcing the end 23 into the end 3
A wave spring 24 is placed on the shoulder 26 so as to bring it closer to zero. End 34 rests on membrane support side 36 of semipermeable membrane 38 . The underside 39 of the membrane 38 is placed against the sensing electrode 40 . Electrode 40 is placed on electrode pad 42 and connected to terminal post 72 by a wire 44 that is routed through compression screw 46 .

An electrode pad 42 is placed on the inner electrode support 43. The support body 43 is made of polysufone.
) A wafer having holes containing an electrolyte. Those holes are connected to the hinge 49. During assembly, recess 4
9 is! This will be the area where the disinfectant will flow. Contained within recess 49 is an electrode 50 that is placed over electrode pad 47 . The support body 43 supports the detection electrode 40 from inside, and the support body 43 supports the detection electrode 40 from inside.
The edges of the electrode pads 47 are sealed to separate the electrode pads 40 from the sensing electrodes 40. A wire 57 passed through the compression screw 55 connects the electrode 50 to the terminal post T3. Electrode pad 4T is placed on counter electrode assembly 60. This counter electrode assembly 71 includes a counter electrode. Counter electrode assembly 60 has a current collector screen 51 covered with powder 52 . The powder is platinum dioxide (PtO2)
It can be done.

The powder is soaked in an aqueous electrolyte solution. Powder 52 is brought into close contact with screen 51. The screen 51 is
Wire 54 is connected to terminal post 74 by threading through screw 56 . Powder 5 on collector screen 51
2 constitutes a counter electrode. An electrode pad 53 is provided at the bottom of the counter electrode assembly 60 to prevent the counter electrode powder 52 from moving. This [pole pad 53 is placed on the counter electrode holder 62. The counterelectrode holder is a perforated, threaded polysulfon cap. The bladder 68 compensates for expansion of the electrolyte caused by heating due to environmental conditions and allows internal body selection to be referenced to ambient pressure to minimize pressure differentials on either side of the seal.

A second threaded retainer 70 extends downwardly from within the lower end 16 of the sensor 10 . This retainer TO has an axial passage 61 and an upper end 63. Juxtaposed to this upper end 63 is an expansion chamber ring 66 having a shoulder 64 . Retainer 7
A wave spring T2 is provided within shoulder 64 such that wave spring 72 is compressed when G contacts shoulder 64.

The electrode 40 is a battery (galvanic c@1l) 74
constitutes half of the The other half of cell T4 is comprised of counter electrode assembly 60. When the diffusion of hydrogen to the detection electrode 40 is blocked by the diffusion membrane or semipermeable membrane 3B, this cell becomes a "senna". All other mechanical components within compensator 10 maintain separation between sensing electrode 40 and counter electrode 51 and also maintain electrolyte.

The battery 74 operates as a battery that uses hydrogen or oxygen as fuel. Hydrogen diffuses through the semipermeable membrane 38 and reaches the detection electrode 4
Absorbed by 0. If an electrolyte is present, the absorbed hydrogen is converted into ions and at the same time releases electrons. Those electrons are captured by the sensing electrode 40 and conveyed to the exterior of the sensor housing by a screw 46 and a wire 44 through a thermistor network as shown in FIG. 3 to a counter electrode collector assembly 60. from there to the counter electrode powder 52.

All internal components other than the electrodes and current collectors are electrically isolated from the electron flow, but are all in contact with the sulfuric acid TrLFn liquid solution that conducts the flow (ie, positive ions).

The hydrogen ions are guided to the counter electrode 52 through the electrolyte. At the counter electrode, the reactants combine with water and possibly an oxide of platinum and a lower form of platinum (t6v@r
form). Since the electron source is hydrogen gas, the current generated is directly representative of the reacted hydrogen. The amount of hydrogen that reaches the sensing electrode is controlled by the rate of diffusion through the thin film. The rate of diffusion is a function of the partial pressure of hydrogen in the atmosphere. Therefore, the current measured is the partial pressure of hydrogen.

The electrode 50 is electrically connected to the detection electrode 40 or the counter electrode 52, as shown in FIG. fix and Rg are thermistors coupled to the positive input terminals of operational amplifier 110. The power between sensing electrode 40 and counter electrode 520 results from hydrogen and environmentally induced anomalies. All hydrogen diffused through the semipermeable membrane 3B is used (converted to H+) at the detection electrode 40. Electrode 5
The output between 0 and counter electrode 52 can only be produced by something other than hydrogen. What is that something?
For example, radiation. Since the outputs from each pair of electrodes are opposite to each other, the signal caused by something other than hydrogen is
canceled out. The resulting compensated signal represents only the signal caused by hydrogen.

FIG. 4 shows a compensator 11 similar to the compensator described above. In this compensator 11, a solid barrier member 38' that prohibits the flow of electrons is used in place of the semipermeable membrane 3B. In this embodiment, third electrode 50 is not required. Because the gas whose partial pressure is to be measured does not reach the counter electrode due to the barrier member 38', no reaction occurs. Therefore, the output of the compensator will be based on anomalies due to the environment.

Next, the operation will be explained. Another embodiment of the compensator is connected in an electrical circuit to a typical gas sensor such as that disclosed in the aforementioned US Pat. No. 3,616,411. Since the gas sensor and compensator 11 are exposed to the same environment, the output signal of the gas sensor represents the combined output of the partial pressure of the gas and the output of the anomaly caused by the environment. The output of the compensator 11 represents only the output caused by radiation.

This circuit takes the difference between two output signals. The environmentally induced output of compensator 11 is subtracted from the output of a typical gas sensor. The only component remaining in the output signal of the combined sensor circuit is that representing the partial pressure of the gas. Therefore, even if an abnormality occurs in the output signal of the gas sensor due to the environment, the partial pressure of the gas can be accurately measured.

One circuit C (FIG. 5) that can determine the difference in output signal output is a simple Wheatstone bridge that includes resistor R1, variable resistor R2, and resistors Rs and R4. A typical gas sensor is connected in parallel with a resistor R,. The connection is made to a terminal post that is connected to the electrode of the gas sensor. The compensator is connected in parallel to variable resistor R1. The output signal of this bridge is connected to the resistor R
1 and applied to a chart recorder 95 for testing. Variable resistor R2 is adjusted so that the recorder reads zero volts when the gas sensor and compensator are in a normal atmosphere. In this configuration, the compensator 11
Since the electromotive force ('BMFJ') generated by This circuit automatically corrects the output of the gas sensor due to radiation-induced anomalies and greatly expands the range of radiation levels over which the gas sensor can accurately measure the partial pressure of a gas.

Although the Wheatstone bridge circuit of FIG. 5 is used in another preferred embodiment of the invention, other standard configurations of bridge circuits may be used.

FIG. 6 shows a circuit configuration different from that shown in FIG. 5 of a typical circuit for determining the difference between the output signals of the gas sensor and the compensator 11. The output signal of the sensor is applied to the positive input terminal of summing amplifier 10G, and the output of the compensator is applied to the negative input terminal of summing amplifier 100. The output of this summing amplifier is then the difference between the two signals, ie the desired compensated output of the gas sensor.

By using the compensator of the present invention inside a nuclear power plant, accidents due to design causes can be monitored more effectively. Before such compensators and circuits were available,
It has been the accepted procedure to wait a certain amount of time (i.e., 3 to 24 hours) before placing an uncompensated gas sensor on line.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the compensation sensor of the present invention, and FIG.
An enlarged sectional view of the sensor shown in the figure along line 2-2.
4 is a partial sectional view of another embodiment of the compensation sensor shown in FIG. 2; FIG. 5 is a diagram of the environment during the output of the gas sensor; FIG. Figure 4 is a circuit diagram of the electrical interconnection between the compensation sensor and a typical gas sensor to compensate for anomalies caused by a FIG. 3 is another circuit diagram of the connection between a compensation sensor and a typical gas sensor. 10@...φ housing, 2G, 7G--fist holder,
38... Semi-permeable membrane, 40... Detection electrode, 50 fist...
... Third electrode, 51 ... Current collector screen, 52
...Powder (counter electrode). Patent applicant: Exo Sensors, Inc., agent: Masaki Yamakawa (and 2 others)

Claims (14)

[Claims] (1) a housing means disposed within the gas; a first electrode means disposed within the housing means; a second electrode means disposed within the housing means; and the first electrode. coupling means to said second electrode means;
a first connection means for generating a first electrical potential indicative of the partial pressure of the gas to be detected, including anomalies caused by the environment; a third electrode means arranged electrically isolated and separated from the gas to be detected; said third electrode means being coupled to said first electrical means or said second electrical means; second connection means for generating a second potential indicative of an abnormality caused by the environment, thereby representing a partial pressure of the gas when the second potential is subtracted from the first potential. A device for detecting the partial pressure of a gas in an environment that produces an anomaly, characterized in that a signal is generated. (2) The device according to claim 1,
An apparatus comprising a circuit for subtracting the second potential from the first potential. (3) The device according to claim 1,
Apparatus characterized in that said first electrode means and said second electrode means are combined to form a galvanic cell. (4) a gas sensor disposed in a gas, the gas sensor having a detection electrode means, a counter electrode means, and a third electrode means separated from the detection electrode means and the counter electrode means; The sensing electrode means and the counter electrode means, when coupled together, generate a first potential indicative of the partial pressure of the gas to be detected, including any environmentally induced anomalies; Means, when electrically coupled to either said sensing electrode means or said counter electrode means, generates a second electrical potential indicative of an environmentally induced anomaly, thereby causing said electrical potential to change from said first electrical potential to said electrical potential. An apparatus for detecting a partial pressure of a gas in an abnormal environment, characterized in that when a second potential is subtracted, a signal representative of the partial pressure of the gas is generated. (5) The device according to claim 4,
An apparatus comprising a circuit for subtracting the second potential from the first potential. (6) The device according to claim 4,
Apparatus characterized in that said third electrode means is coupled to said detection electrode means. (7) The device according to claim 4,
Apparatus characterized in that said third electrode means is coupled to said counter electrode means. (8) a cylindrical housing means having a first end and a second end; a first end having an axial passageway and a lower end disposed within the first end of the cylindrical housing means; a cylindrical thin film holding means disposed close to the lower end of the environment holding means; a semipermeable membrane means juxtaposed to the cylindrical thin film holding means; and connected to the first terminal means. a sensing electrode means connected to and electrically isolated from the sensing electrode means, and a third terminal means; and a current collector assembly means connected and coated with powder, wherein the first terminal means is connected to the third terminal means to detect any environmentally induced anomaly, including any environmentally induced anomaly. a potential is generated indicative of a partial pressure of a gas, and when said second terminal is coupled to either said first terminal and said second terminal, a second electrical potential indicative of an environmentally induced anomaly is generated; of a gas in an abnormal environment, characterized in that an electric potential is generated, such that when the second electric potential is subtracted from the first electric potential, a signal representative of the partial pressure of the gas is generated. A device that detects partial pressure. (9) The device according to claim 8,
An apparatus comprising a circuit for subtracting the second potential from the first potential. (10) A gas sensor that has a detection electrode means and a counter electrode means and is disposed within the gas to be detected and generates a first output signal; The counter electrode means and the detection electrode means separated from the gas to be detected. and a compensation sensor generating a second output signal, wherein when the second output signal is subtracted from the first output signal, the resulting signal represents the partial pressure of the gas to be detected. Apparatus operating in an environment containing an anomaly to generate an output signal indicative of the presence of a detected gas, characterized in that: (11) An apparatus according to claim 10, characterized in that it comprises means for calculating the difference between the second output signal and the first output signal. (12) The apparatus according to claim 11, wherein the means comprises a circuit having a Wheatstone bridge connected to the recording means. (13) The device according to claim 12, wherein the Wheatstone bridge is: a first resistor connected between an output terminal of the gas sensor; and an output terminal of the compensation sensor. a third resistor connected to the detection electrode means of the gas sensor; and a third resistor connected to the detection electrode of the compensation sensor and connected to the third resistor. a fourth resistor, whereby the output signal is measured by the recording means across the terminals of the first resistor. (14) The device according to claim 11, wherein the means for taking the difference comprises a summing amplifier.