JP2002062278A - Instrument for measuring gas purity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute an instrument for real-time measurement of gas purity, using a difference of strength of an ionization current which flows by ionization of gas by a radiation. SOLUTION: This instrument is constituted of a gas purity measuring chamber provided with a gas inlet and a gas outlet, positive and negative electrodes provided in a gas flow passage inside the measuring chamber, a radiation source for emitting the radiation toward the gas passing through a space between the electrodes, an ammeter provided in a circuit connected to both electrodes, and a measured purity processing circuit connected to the ammeter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a real-time apparatus for measuring the purity of a gas by utilizing the difference in the magnitude of an ionization current flowing when gas is ionized by radiation.

[0002]

2. Description of the Related Art In the conventional gas analysis, a method of introducing a small gas into a vacuum-evacuated chamber, analyzing the components using a quadrupole mass analyzer or the like, and calculating the components of the original gas from the analysis results is known. Used.

[0003]

However, in such a conventional method, it is impossible to directly analyze a gas at a high pressure, and it is also difficult to know its components immediately. The present invention solves these disadvantages,
It can be installed in a gas flow path to measure gas purity in real time.

[0004]

According to the present invention, there is provided a gas purity measuring apparatus comprising: a gas purity measuring chamber provided with a gas inlet and a gas outlet; an anode electrode and a negative electrode plate provided in a gas flow path in the measuring chamber; It comprises a radiation source for irradiating the gas passing between the plates with radiation, an ammeter provided in a circuit connecting the two electrode plates, and a measurement purity processing circuit connected to the ammeter.

In the gas purity measuring device of the present invention, the gas to be measured is introduced from the gas inlet to between the electrodes in the measuring chamber, and the gas to be measured flowing between the electrode plates is irradiated with radiation to ionize it by ionization. By applying a voltage between the electrode plates and measuring the current flowing between the electrodes, and comparing the magnitude of the measured current with the previously measured measurement current of the same gas, the gas to be measured flowing between the electrode plates is measured. The purity of is measured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When a gas is irradiated with radiation, the gas is ionized and exhibits conductivity. When an opposing electrode plate is placed there and a voltage is applied, a current flows between the electrodes. This phenomenon has been applied to conventional radiation measuring instruments. The magnitude of the flowing current is
It depends on the applied voltage, the amount of radiation and the pressure of the gas.
In addition, since the ionization current is also determined by the type of gas, by measuring the ionization current of a certain gas due to radiation of a predetermined intensity, the purity of the gas can be determined from the deviation from the current value.

For example, the purity of SF6 (sulfur hexafluoride), which is used as a high-voltage insulating gas, is important when used in electrical equipment, and also when purified from a mixed state of air or the like. Monitoring its purity is essential.

A gas purity measuring apparatus according to the present invention will be described with reference to FIG. A gas inlet is provided on one side wall of the gas purity measuring chamber 1, and a gas outlet is provided on the opposite side wall.
Two electrode plates are arranged between a gas inlet and a gas outlet in the measurement chamber, and a circuit is formed between the electrode plates, and an ammeter A is inserted into the circuit. Furthermore, in the measurement room,
A radiation source is provided for irradiating the gas to be measured passing between the electrode plates with radiation. A measurement purity processing circuit is coupled to the ammeter, and the circuit operation measures the purity of the gas to be measured based on the measurement current.

In the measuring apparatus of the present invention, when a gas is irradiated with radiation, the gas is ionized and becomes conductive.
Therefore, when a voltage is applied between the opposing electrode plates, a current flows between the electrodes. The current flowing at that time is determined by the voltage applied between the electrode plates, the amount of irradiated radiation, and the pressure and type of the gas to be measured.

[0010] The current flowing at that time also differs depending on the type of gas. Therefore, a gas of the same kind as the gas to be measured is ionized by radiation of a predetermined intensity, and the current between the electrodes at that time is measured, whereby the measured current value of the gas to be measured is measured in advance. The purity of the gas to be measured can be measured based on the deviation from the set current value.

To measure the purity of the gas to be measured based on the deviation from the current value, for example, first, SF6 gas of various concentrations with a known pressure is used as a standard gas, and a predetermined intensity At various concentrations of S
The inter-electrode current measured corresponding to the F6 gas is measured, and a table or graph relating to concentration versus current value is created based on the measured current. Next, radiation of the same intensity as that of the standard gas is applied to the SF6 gas having an unknown concentration at the same pressure as that of the standard gas, and the current between the electrodes at that time is measured. By comparing the measured current value of the gas having the unknown concentration with the current value in a table or a graph prepared for standard gases having various concentrations, the SF6 concentration of the gas can be known.

[0012]

By attaching the apparatus of the present invention to a gas flow path, the state of purification and the state of purity of the gas can be easily measured. The apparatus of the present invention is SF
It can also be used to measure the purity of gases other than 6,
Its applicability is wide.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a gas purity measuring device of the present invention.

[Explanation of symbols]

 1: Gas purity measurement room

Claims (2)

[Claims] A gas purity measuring chamber provided with a gas inlet and a gas outlet; an anode electrode and a negative electrode plate provided in a gas flow path in the measuring chamber; and a gas for irradiating a gas passing between the electrode plates with radiation. A gas purity measuring device comprising: a radiation source; an ammeter provided in a circuit in which both electrode plates are coupled; and a measurement purity processing circuit coupled to the ammeter. 2. The apparatus according to claim 1, which is used for measuring the purity of SF6 (sulfur hexafluoride) gas used in electrical equipment as a high-voltage insulating gas.