JPS599549A - Measurement of gas concentration - Google Patents

Abstract

PURPOSE:To achieve the measurement of gas concentration in a handy, safe and accurate manner by mixing a dry gas other than a specified gas at a certain rate to maintain the water in a gas to be measured within the applicable range of a gas analyzer when the concentration of the specified gas is measured in the gas to be measured containing water. CONSTITUTION:For example, in the measurement of H2O2 and the like in a gas of a high temperature and high humidity for example in a gas within a vessel housed in a nuclear reactor, a dry gas such as N2 is mixed with a sample gas sent via a needle valve 14 and a flowmeter 15 through a pipe 17 passing through a pressure regulation valve 16 and the mixture is sent to an oxygen analyzer 10 and a hydrogen analyzer 11 through a flow control valve 7 and a flowmeter 8 to measure concentrations of the gases. An excessive gas above the required level for analysis flows to the flow control valve 13. Thus, in stead of the use of a dehumidifier of the sample gas, a certain amount of the dry gas is added within the applicable range of the analyzers 10 and 11 whereby the measurement can be made possible accurately with a simple equipment without danger of making H2 and O2 an explosive gas respectively.

Description

Detailed Description of the Invention [Technical details of the invention] The present invention is applicable to specific gases in a gas to be measured whose moisture content exceeds the usable range of a gas analyzer. The present invention relates to a gas concentration measuring method for measuring the oxygen gas concentration and hydrogen gas iM of internal gas.

[Technical background of the invention]

Generally, in the event of a loss of coolant accident in a boiling water nuclear power generation facility, the gas inside the reactor containment vessel is sampled and the oxygen gas concentration and hydrogen gas concentration are measured. As is well known, the gas inside the containment vessel is high temperature and humid, so it can condense when cooled during measurement, and the moisture content can interfere with measurement. Therefore, after dehumidifying and cooling the sampled gas to be measured, It is supplied to the analyzer and hydrogen analyzer.

As shown in FIG. 1, a gas analysis system using this method uses a sampling pump 1 to which a needle valve 2 is connected in parallel to limit the maximum pressure between a gas inlet and an outlet. is attracted,
Next, it is fed into the dehumidifying cooler 5 via the pressure regulating valve 3 that keeps the outlet pressure constant. In this case, a pressure gauge 4 is connected to the outlet side of the pressure regulating valve 3, thereby monitoring the gas pressure.

The gas to be measured sent to the dehumidifying cooler 5 is dehumidified there, and then sent to the oxygen analyzer 10 and hydrogen analyzer 11 via the flow rate adjustment valve 7, where the oxygen gas concentration and hydrogen gas concentration are measured. be done.

Note that a flow meter 8 and a pressure gauge 9 are provided between the flow rate adjustment valve 7 and the oxygen analyzer 10 and hydrogen analyzer 11.
A constant acid test gas is monitored to be supplied to these analyzers.

The gas to be measured whose concentration has been measured (1) is returned to the reactor containment vessel by the sampling pump 12, and (a) the water separated by dehumidification of the gas to be measured is discharged through the water valve 6 and separately It is processed.

In this way, the moisture content in the gas to be measured is determined by the oxygen analyzer 10.
Even if the water exceeds the usable range of the hydrogen analyzer 11, most of this moisture is removed by the dehumidifying cooler 5, so the oxygen and hydrogen gas concentrations in the gas to be measured can be reliably measured. can be measured.

[Problems with background technology]

Measuring gas concentration using such a conventional method requires a dehumidifying cooler 5 and a step to treat the moisture generated in the dehumidifying cooler 5, which complicates the measuring system and requires extra operations and operations. The disadvantage is that it requires management.

In addition, dehumidification causes the oxygen and hydrogen gas concentrations in the gas to be measured to become relatively high, and there is a risk that dehumidification will exceed the limit of explosive gas, which was below the limit due to moisture content. Furthermore, there is a drawback that complicated correction is required for the measured gas concentration.

(4) [Object of the Invention] The present invention has been made to eliminate the drawbacks of the conventional methods described above. The purpose of the present invention is to provide a gas concentration measuring method that can accurately and safely measure gas concentration while eliminating the need for processing drain water generated by dehumidification. The present invention uses a gas analyzer to measure the moisture content of the gas to be measured by mixing the gas to be measured and a drying gas other than the specific gas whose concentration is to be measured contained in the gas to be measured at a constant ratio. is maintained within a usable range, the gas concentration of the specific gas in the mixed gas is measured, and the specific gas concentration in the measured gas is calculated using the measurement result and the mixing ratio of the mixed gas. It is said that

[Embodiments of the invention]

The present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a system diagram of a gas measuring device that performs the entire gas concentration measuring method according to the present invention. In the same way as described above, the gas inside the reactor vessel is added as the gas to be measured, and the oxygen gas in this gas to be measured is The purpose is to measure the concentration and hydrogen gas concentration.

In the figure, the same reference numerals as in FIG. 1 indicate the same elements. Then, the dehumidifying cooler 5 in FIG. 1 is removed, and the outlet side of the pressure regulating valve 3 and the sampling pump 12 are removed.
A flow regulating valve 13 is newly installed between the inlet side of the pressure regulating valve 3 and a needle valve 14 and a flow meter 15 are newly installed between the outlet side of the pressure regulating valve 3 and the inlet side of the flow regulating valve 7. A pressure regulating valve 16 capable of supplying drying gas at a constant pressure is newly provided on the inlet side of the fuel cell 7.

In FIG. 2, the gas inside the reactor containment vessel, that is, the gas to be measured, is sucked by a sampling pump 1,
The pressure is maintained at a constant pressure by the pressure regulating valve 3. Most of this constant pressure gas to be measured is guided to the inlet side of the sampling pump 12 through the flow rate regulating valve 13 and returned to the reactor containment vessel. On the other hand, the remaining gas to be measured, that is, the gas to be measured that is subjected to concentration measurement, is transferred to the needle valve 14 and the flow meter 15.
The drying gas is completely guided to the inlet side of the flow rate regulating valve 15 and is fed here through the pressure regulating valve 16;
For example, it is mixed with nitrogen gas. As a result, the gas to be measured diluted with nitrogen gas is supplied to the oxygen analyzer 10 and the hydrogen analyzer 11 through the flow rate adjustment valve 7 and the flow meter 8, and then the gas to be measured after concentration analysis is supplied to the flow rate adjustment valve 7 and the flow meter 8. It is returned to the reactor containment vessel in a mixed state with the gas to be measured passing through 13.

In this case, the outlet pressure of the pressure regulating valve 3 and the pressure regulating valve 1
Since both outlet pressures of No. 6 are kept constant, a certain amount of gas to be measured and a certain amount of drying gas are mixed, and the moisture content in the mixed state is measured by an oxygen analyzer. The flow rate and pressure of each pressure regulating valve, flow regulating valve, and needle valve are set so as to be within the usable range of the hydrogen analyzer.

Thus, by multiplying the measured values of the oxygen analyzer 10 and the hydrogen analyzer 11 by the ratio of the flow rate value of the flow rate 1t15 and the flow rate value of the flow meter 80, that is, the mixing ratio, the oxygen gas in the reactor containment vessel gas is determined. The concentration and hydrogen gas concentration can be measured accurately and easily.

On the other hand, all of the gas to be measured drawn out by the sampling pump 1 is returned to the reactor containment vessel in a state mixed with nitrogen gas, so there is no need to treat drain water, which was unavoidable with conventional methods. Furthermore, the disadvantage of the conventional method that the oxygen gas concentration and hydrogen gas concentration in the gas to be measured increase during measurement is eliminated.

Note that, since the gas inside the reactor containment vessel is hot and humid, it is conceivable that dew may form in the pipes leading this gas.

In order to prevent such a situation, a heat trace 17 is provided in FIG. 2 to appropriately heat the area where dew condensation is expected.

By the way, although this is a method normally adopted for this type of gas analyzer, the oxygen analyzer 10 and the hydrogen analyzer 11
Here, by supplying a calibration gas for calibrating between the sampling pump 1 and the pressure regulating valve 3,
Each flow rate adjustment valve or pressure adjustment valve is operated in the same way as when actually measuring concentration (7).

In the above example, the case where the gas to be measured is the gas inside the reactor containment vessel was explained, but the same concentration measurement can be performed for the gas to be measured whose moisture content exceeds the usable range of the gas analyzer. It is possible, and the specific gas in the gas to be measured, that is, the gas to be measured, is not limited to oxygen and hydrogen, and may be gases other than these.

In addition, in the above embodiment, a drying gas and a general nitrogen gas were used, but it goes without saying that other gases may be used as long as they do not affect the measurement accuracy. .

〔Effect of the invention〕

As is clear from the above description, the gas concentration measuring method of the present invention eliminates the need for a dehumidifying cooler and its associated drain water treatment line, simplifying the concentration measuring system and at the same time requiring unnecessary operations and Management becomes unnecessary.

In addition, since the gas to be measured is simply diluted, the concentration of the gas to be measured can be easily determined by simply multiplying the measured concentration and the dilution rate, that is, the mixing ratio of the gas to be measured and the drying gas (8). Complicated corrections for dehumidification, which were unavoidable with conventional methods, are no longer required. Furthermore, by mixing the measured gas and the drying gas 1.', the oxygen gas concentration and hydrogen gas concentration during gas analysis can be reduced. As the concentration decreases, there is no danger that the gas to be measured becomes explosive gas, and excellent effects such as safe concentration measurement can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the configuration of a concentration measurement system according to a conventional gas concentration measurement method, and FIG. .

Claims (1)

[Claims] 1. A gas concentration measuring method for measuring the concentration of a specific gas in a gas to be measured containing moisture, wherein the gas to be measured;
By mixing a drying gas other than the specific gas at a constant ratio, the moisture content of the gas to be measured is kept within the usable range of a gas analyzer, and the concentration of the specific gas in the mixed gas is measured. A method for measuring gas concentration, characterized in that the concentration of a specific gas in the gas to be measured is calculated using the measurement result and the mixing ratio of the mixed gas. 2. The gas concentration measuring method according to claim 1, characterized in that the flow rates of the gas to be measured and the drying gas are measured during mixing, and the flow rate ratio of these gases is used as the mixing ratio. 3. The method according to claim 1, wherein the gas to be measured is a gas in a reactor containment vessel, the specific gas is oxygen gas or hydrogen gas, and nitrogen gas is used as the drying gas. Gas concentration measurement method.