JP2012047659A - Hydrogen concentration measurement apparatus with humidity correction function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain highly accurate hydrogen concentration measurement by correcting a measurement error caused by variation of humidity which is a composition of gas subjected to measurement in a hydrogen concentration measurement apparatus.SOLUTION: A hydrogen concentration detector 7 of a hydrogen concentration measurement instrument 12 is installed in a sampling line 2 for supplying sampling gas 1 acquired from an outlet of a recombiner of hydrogen and oxygen of a nuclear power plant. An oxygen concentration detector 5 of an oxygen concentration measurement instrument 11, a pressure detector 4 of a pressure measurement instrument 10, and a humidity detector 3 of a humidity measurement instrument 9 are installed on the upstream side of an installation position of the hydrogen concentration detector 7. Measurement results by the respective measurement instruments are input in a correction operation unit 13, and correction values of hydrogen concentration measurement values corresponding to the respective measurement results are added or subtracted to or from the measured hydrogen concentration measurement results, by the correction operation unit 13, based on correlation of correction values of hydrogen concentration with oxygen concentration, pressure, and humidity to raise accuracy of the hydrogen concentration measurement.

Description

  The present invention relates to an apparatus for measuring a hydrogen concentration in a sampling gas whose humidity varies.

  In a nuclear power plant having a boiling water reactor among the nuclear power plants, a large amount of hydrogen molecules and oxygen molecules are contained in the exhaust gas generated from the air extractor in the power plant. The hydrogen molecules and oxygen molecules are bonded to water molecules by a recombiner, and water generated by the bonding is dehumidified by a dehumidifying cooler. The dehumidified exhaust gas is appropriately treated in an activated carbon type rare gas holdup tower and then exhausted outside the power plant.

  A hydrogen concentration measurement device for measuring the hydrogen concentration in the sampling gas sampled from the recombiner outlet for the purpose of monitoring that the hydrogen and oxygen bonding function in the recombiner is functioning soundly. Is provided.

  The hydrogen concentration depends on the process pressure and temperature of the sampling gas. For this reason, in the hydrogen concentration measuring device, a hydrogen concentration detector for detecting the hydrogen concentration and a correction arithmetic unit capable of correcting the signal detected by the hydrogen concentration detector with an arbitrary input signal are installed. The corrected hydrogen concentration value can be measured.

  In the prior art, a measuring apparatus that uses the process pressure and temperature of a sampling gas as a correction signal in an atmosphere monitor in a reactor containment vessel has been proposed (for example, see Patent Document 1).

  Although it relates to a fuel cell system, it is known to correct the normalized output with humidity and a humidity correction formula to obtain the concentration of a gas to be detected such as hydrogen mixed with the atmosphere containing moisture ( For example, see Patent Document 2).

  Although it is related to the gas chromatograph of the exhaust gas measuring device, it is known to include a correction calculation unit that corrects the analysis value in the gas chromatograph based on the values detected by the concentration detection device and the humidity detection device (for example, And Patent Document 3).

  This is related to the hydrogen detection system. The hydrogen component in the taken-in gas is converted to water, and the moisture content in the gas discharged from the hydrogen reaction part after the water generation reaction is measured with a hygrometer. It is known to detect the amount of hydrogen (see, for example, Patent Document 4).

  This relates to a heater control device for a heater built-in type gas sensor. A humidity sensor is provided upstream from the installation position of the hydrogen gas sensor, and the humidity (humidity detection value) of the gas to be detected upstream from the hydrogen gas sensor is predetermined. It is known to control the start and stop of energization of the heater of the hydrogen gas sensor in accordance with the determination result of whether or not the threshold humidity is higher than the threshold humidity (see, for example, Patent Document 5).

JP 2000-2784 A JP 2004-354210 A Japanese Patent Laid-Open No. 2008-216025 JP 7-325075 A JP 2009-128221 A

  The hydrogen concentration detector depends not only on the process pressure and temperature of the sampling gas but also on the humidity. In addition, the hydrogen concentration measuring apparatus calibrates at the same pressure as the actual measurement in order to perform an accurate measurement, but the pressure is different from that at the time of calibration in the actual process, resulting in a measurement error due to the pressure. In addition, since fluctuations in humidity greatly change the indicated value of the hydrogen concentration detector, conventionally, a dehumidifier has been installed upstream of the hydrogen concentration detector to remove moisture in the sampling gas. However, in practice, moisture cannot be completely removed, so there is a measurement error due to humidity. Therefore, even if the temperature is corrected as a correction signal as in Patent Document 1, the measurement error cannot be eliminated.

  Moreover, although the thing of patent document 2 implement | achieves gas detection and humidity detection with one element by changing the electric current sent through a heat generating element, this method can measure hydrogen concentration only intermittently. However, since the nuclear power plant requires continuous measurement of the hydrogen concentration for the purpose of monitoring the hydrogen concentration of the gas waste treatment system, the one described in Patent Document 2 cannot satisfy the above-described requirement.

  Further, the one described in Patent Document 3 includes an exhaust gas detection line (a supply pipe 13a to a gas chromatograph 2 line in Patent Document 3) and a humidity detection line (an exhaust gas supply pipe 17a to a hygrometer 4 in Patent Document 3). Line) is divided. As described above, if the detection lines are different, there is a possibility that the gas state may be different.

  Moreover, since the thing of patent document 4 makes hydrogen react, it is made water, and since hydrogen concentration is detected from the amount of moisture, it cannot measure the hydrogen which has not reacted, and therefore hydrogen concentration measurement accuracy There is a problem.

  In addition, a device described in Patent Document 5 is a device in which a humidity sensor is attached to acquire information for controlling a heater that prevents dew condensation on the sensor, and the humidity indication value is the indication value of the hydrogen concentration meter. It is not used as correction data for the measurement, and does not achieve improvement in measurement accuracy.

  Accordingly, an object of the present invention is to continuously and accurately measure the hydrogen concentration.

  Means for achieving the object of the present invention is to provide a hydrogen concentration measuring apparatus in which a hydrogen concentration detector is installed in a sampling line through which a sampling gas to be measured passes, and the flow of the sampling gas rather than the installation position of the hydrogen concentration detector. A humidity detector that detects the humidity of the sampling gas installed on the same line as the sampling line upstream of the sensor, and a hydrogen concentration measurement value by the hydrogen concentration detector based on a humidity measurement value by the humidity detector It is a hydrogen concentration measuring apparatus with a humidity correction function, characterized in that it includes a correction calculation unit for correcting.

  Install a hydrogen concentration detector on the same sampling line and a humidity detector on the upstream side to measure the humidity and hydrogen concentration without being affected by the heat generated by the hydrogen concentration detector and in the same sampling gas state. Thus, the hydrogen concentration measurement value is corrected by the correction calculation unit due to the humidity fluctuation, so that continuous and highly accurate hydrogen concentration measurement can be realized.

It is a systematic diagram of the hydrogen concentration measuring apparatus by the Example of this invention. It is a flowchart of the correction process of the hydrogen concentration measured value by the Example of this invention. It is a graph which shows the humidity dependence of the hydrogen concentration correction value in the Example of this invention. It is a graph which shows the oxygen concentration dependence of the hydrogen concentration correction value in the Example of this invention. It is a graph which shows the pressure dependence of the hydrogen concentration correction value in the Example of this invention.

  In the embodiment of the present invention, in the hydrogen concentration measuring apparatus in which the hydrogen concentration detector 7 is installed in the sampling line 2 through which the sampling gas 1 to be measured passes, the upstream of the flow of the sampling gas 1 from the installation position of the hydrogen concentration detector 7. The humidity detector 3 for detecting the humidity of the sampling gas 1 installed on the same line as the sampling line 2 on the side and the hydrogen concentration measurement value by the hydrogen concentration detector 7 are corrected based on the humidity measurement value by the humidity detector 3 The correction calculation unit 13 is provided, and the correction result is displayed on the instruction unit 15 which is a display unit, and a concentration signal for recording / warning is output to the outside through the alarm circuit 14.

  Thus, by correcting the measured hydrogen concentration value based on the humidity of the sampling gas, a hydrogen concentration measuring device with little measurement error due to humidity can be provided without sacrificing measurement continuity and correction accuracy.

  Embodiments of the present invention will be described more specifically with reference to the drawings. FIG. 1 shows a system of a hydrogen concentration measuring apparatus according to Embodiment 1 of the present invention.

  In a nuclear power plant having a boiling water reactor among nuclear power plants, hydrogen molecules and oxygen molecules contained in a large amount in exhaust gas generated from the air extractor in the power plant are combined with water molecules by a recombiner, and the combination The water generated by is dehumidified by a dehumidifying cooler. The dehumidified exhaust gas is appropriately treated in an activated carbon type rare gas holdup tower and then exhausted outside the power plant.

  Hydrogen concentration for measuring the hydrogen concentration in the sampling gas 1 collected from the outlet of the recombiner for the purpose of monitoring that the bonding function of hydrogen molecules and oxygen molecules is functioning soundly in the recombiner. A measuring device is provided.

  In addition, the nuclear power plant is required to continuously measure the hydrogen concentration in the sampling gas 1 collected from the gas waste treatment system outlet for the purpose of monitoring the hydrogen concentration of the gas waste treatment system. A hydrogen concentration measuring device for continuously measuring the hydrogen concentration in the sampling gas 1 collected from the gas waste treatment system outlet is provided.

  As shown in FIG. 1, the hydrogen concentration measuring apparatus causes the gas to be measured to flow as sampling gas 1 to the sampling line 2 from the outlet of a device that discharges the gas to be measured. The direction in which the sampling gas 1 flows is the direction in which the arrow of the sampling gas 1 is directed. The sampling line 2 is constituted by a pipe through which the sampling gas 1 flows.

  The sampling line 2 is equipped with a flow meter 6 and a constant flow valve 8, and a sampling gas flowing through the sampling line 2 by the hydrogen concentration detector 7 of the hydrogen concentration measuring device 12 is located in the portion of the sampling line 2 between them. It is installed so that the hydrogen concentration in 1 can be detected.

  On the same sampling line 2 as the sampling line 2 where the hydrogen concentration detector 7 is installed, the humidity detector 3 of the humidity measuring device 9, the pressure detector 4 of the pressure measuring device 10, and the oxygen concentration of the oxygen concentration measuring device 11. The detector 5 is provided so as to measure the sampling gas 1 flowing in the sampling line 2.

  The installation positions of these detectors are installed upstream of the sampling gas flow from the installation position of the hydrogen concentration detector 7. Even if the hydrogen concentration detector 7 is a detector of a type having a heating unit, each detection in the source state is not affected by heat or temperature from the heating unit. It is considered so that the detection accuracy can be maintained, and the calibration accuracy when the hydrogen concentration measurement value is calibrated based on the detection result can be maintained.

  The humidity measuring device 9, the pressure measuring device 10, the oxygen concentration measuring device 11, and the hydrogen concentration measuring device 12 are connected to the correction calculating unit 13 so that the measurement result is input to the correction calculating unit 13. The correction calculation unit 13 is connected to an instruction unit 15 that displays a correction result by the correction calculation unit and an alarm circuit 14 that outputs a concentration signal for recording and alarming to the outside.

  The hydrogen concentration measuring apparatus having such a configuration has the following effects. That is, the sampling gas 1 flowing through the sampling line 2 is maintained at a constant pressure and flow rate by the constant flow valve 8 and the flow meter 6, and the humidity detector 3, the oxygen concentration detector 5, the hydrogen concentration detector 7, and the pressure detector. 4 is activated. This detects humidity, oxygen concentration, and hydrogen concentration, respectively. Further, the pressure detector 4 also detects the pressure of the sampling gas 1.

  The humidity measuring device 9 receives a detection signal from the humidity detector 3 and represents a humidity signal, and the oxygen concentration measuring device 11 receives a detection signal from the oxygen concentration detector 5 and receives an oxygen concentration signal representing the oxygen concentration. Similarly, the hydrogen concentration measuring device 12 receives a detection signal from the hydrogen concentration detector 7 and receives a detection signal from the pressure detector 4, and the pressure measuring device 10 receives a detection signal from the pressure detector 4 and indicates a pressure. Each signal is input to the correction calculation unit 13.

  The correction calculation unit 13 corrects the value of the hydrogen concentration signal as will be described later, outputs the correction result to the instruction unit 15, displays the corrected hydrogen concentration signal on the instruction unit 15, and outputs an alarm together with this. A hydrogen concentration signal is output to the outside for recording / warning through the circuit 14.

  Thereby, even when the detection signal output from the hydrogen concentration detector 7 fluctuates due to the humidity change of the sampling gas 1, the correction calculation unit 13 can correct the hydrogen concentration signal and keep the measurement error to a minimum. More accurate hydrogen concentration measurement is possible.

  Next, a flow of correcting the influence of the humidity concentration instruction value by humidity, pressure, and oxygen in the correction calculation unit 13 is shown in FIG. The correction of humidity, oxygen concentration, and pressure through steps S1 to S3 in FIG. 2 is added to the hydrogen concentration at the time of measurement before correction, and the corrected hydrogen concentration is corrected to the effect of humidity, oxygen concentration, and pressure. get.

  Before performing the correction, the hydrogen concentration meter used at the nuclear power plant has a hydrogen concentration detector attached to the sampling line that actually performs the measurement, and the lower and upper limits of the measurement range are determined in order to determine the lower and upper limits of the measurement range. A gas with a known composition corresponding to is flowed to adjust the output of the instrument.

  That is, first, a hydrogen concentration detector is attached to a sampling line for actual measurement, and the output of the instrument is adjusted with a gas whose composition is known. The time to make this adjustment is called calibration. Next, a sampling gas whose humidity is actually unknown is caused to flow through the sampling line, and the hydrogen concentration is measured during plant operation. The time when the actual measurement is performed is called the measurement time. The same calibration and measurement data is acquired for the output of the oxygen concentration and pressure gauges.

  First, the influence of humidity is corrected from the hydrogen concentration H1 and the humidity measured by the hydrogen concentration detector 7 and the hydrogen concentration measuring device 12 in step S1 of FIG.

FIG. 3 shows the humidity dependence of the hydrogen concentration correction value. The horizontal axis represents humidity, and the vertical axis represents the hydrogen concentration correction value. The deviation between the humidity during calibration and the humidity during measurement is a1, and the hydrogen concentration meter correction value at this time is k1 from FIG. At this time, the hydrogen concentration H2 corrected by humidity is expressed by the following equation.
H2 = H1-k1 (1)

  Correction by humidity is performed by this equation (1).

Here, a specific example of correction will be described as an example of humidity as follows. The shift amount of the indicated value of the hydrogen concentration, that is, the hydrogen concentration correction value is k1, and the humidity is x, and the following correlation is obtained. However, when the humidity is 14.4%, the reference is k1 = 0.
k1 = 0.245x ² + 0.2021x−0.0338

  Assuming that the humidity at the time of calibration is 14.4%, the humidity at the time of measurement is 90.0%, and the indicated value of the hydrogen concentration meter at the time of measurement is 1.0%, k1 = 0.33% from the above formula. Since H1 = 1.0%, H2 = 1.0-0.33 = 0.67% from the equation (1). This correction shows the hydrogen concentration corrected for the influence of humidity.

  Next, the influence of oxygen is corrected from the hydrogen concentration and oxygen concentration corrected for humidity in step S2 of FIG.

FIG. 4 shows the oxygen concentration dependence of the hydrogen concentration correction value. The horizontal axis represents the oxygen concentration, and the vertical axis represents the hydrogen concentration correction value. The deviation between the oxygen concentration during calibration and the oxygen concentration during measurement is a2, and the hydrogen concentration correction value at this time is k2 from FIG. The hydrogen concentration H3 corrected by the oxygen concentration is expressed by the following equation.
H3 = H2-k2 (2)

  The correction by the oxygen concentration is performed by this equation (2).

  Next, the influence of pressure is corrected from the hydrogen concentration and pressure corrected for humidity and oxygen concentration in step S3 of FIG.

FIG. 5 shows the pressure dependence of the hydrogen concentration correction value. The horizontal axis represents pressure, and the vertical axis represents the hydrogen concentration correction value. The difference between the pressure at the time of calibration and the pressure at the time of measurement is a3, and the hydrogen concentration correction value at this time is k3 from FIG. The hydrogen concentration H4 corrected by the pressure is expressed by the following equation.
H4 = H3-k3 (3)

  Correction by pressure is performed by this equation.

  Further, the influence of temperature is corrected from humidity correction, oxygen concentration correction, and pressure corrected hydrogen concentration and temperature in accordance with necessity, such as when there is a temperature fluctuation. Also for this correction, like the correction described in connection with Steps 2 and 3, the correlation between the shift amount of the output of the hydrogen concentration meter and the temperature is obtained in advance, and the shift amount of the output is subtracted during actual plant operation. Correct with.

  When correcting the influence of such temperature, a temperature detector of a temperature measuring device is attached so that the temperature of the sampling gas 1 can be detected in the middle of the sampling line 2 upstream of the hydrogen concentration detector 7. The detection result is input to the correction calculation unit 13.

  In this way, the calibration gas is selected so that the pressure, humidity, temperature, and oxygen concentration during calibration are the same as those during plant operation. Since the pressure, humidity, temperature, and oxygen concentration differ from those at the time of calibration due to changes in the composition, the correlation between the shift amount of the output of the hydrogen concentration meter and the pressure, humidity, temperature, and oxygen concentration should be obtained in advance and during actual plant operation. Correction is made by subtracting the shift amount of the output.

  As described above, the hydrogen concentration can be measured with high accuracy by performing the correction in steps S1 to S3 in FIG. Note that the correction in each step may be performed in any order.

  INDUSTRIAL APPLICABILITY The present invention can be used for facilities that sample gas discharged from the outlet of an oxygen-hydrogen recombiner installed in a nuclear power plant and measure the hydrogen concentration in the gas.

DESCRIPTION OF SYMBOLS 1 Sampling gas 2 Sampling line 3 Humidity detector 4 Pressure detector 5 Oxygen concentration detector 6 Flowmeter 7 Hydrogen concentration detector 8 Constant flow valve 9 Humidity measuring device 10 Pressure measuring device 11 Oxygen concentration measuring device 12 Hydrogen concentration measuring device 13 Correction calculation unit 14 Alarm circuit 15 Instruction unit

Claims (3)

In a hydrogen concentration measurement device with a hydrogen concentration detector installed in the sampling line through which the sampling gas to be measured passes,
A humidity detector for detecting the humidity of the sampling gas installed in the same line as the sampling line upstream of the sampling gas flow from the installation position of the hydrogen concentration detector;
A hydrogen concentration measuring apparatus with a humidity correction function, comprising: a correction calculation unit that corrects a hydrogen concentration measurement value obtained by the hydrogen concentration detector based on a humidity measurement value obtained by the humidity detector.   2. The calculation function according to claim 1, wherein the correction calculation unit subtracts a hydrogen concentration correction value corresponding to the humidity measurement value obtained from the correlation between the hydrogen concentration correction value and the humidity from a hydrogen concentration before the influence of humidity is corrected. A hydrogen concentration measuring device with a humidity correction function, comprising: 3. The oxygen concentration, pressure, and temperature of the sampling gas installed in the same line as the sampling line upstream of the sampling gas flow from the installation position of the hydrogen concentration detector according to claim 1 or claim 2. Another detector for detecting at least one of
The correction calculation unit includes a calculation function for correcting a hydrogen concentration measurement value obtained by the hydrogen concentration detector based on the humidity measurement value and a measurement value obtained by the other detector. Concentration measuring device.

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