JP5750061B2 - Device for measuring hydrogen concentration in sampling gas - Google Patents

Description

  The present invention relates to a hydrogen concentration measuring device for sampling gas extracted from exhaust gas generated from a nuclear reactor at the time of in-service (operation) in a nuclear power plant.

  In nuclear power plants having boiling water reactors such as BWR and ABWR among nuclear power plants, the exhaust gas containing steam generated from the nuclear reactor of the nuclear power plant contains water that has been irradiated with neutrons in the reactor. It contains a large amount of hydrogen and oxygen molecules produced by radiolysis. Furthermore, radioactive noble gas generated by radiolysis in the furnace leaks from the nuclear fuel and enters the exhaust gas.

  In order to remove hydrogen molecules and oxygen molecules in the exhaust gas and to reduce radioactive gas waste such as radioactive noble gases, a gas waste treatment system is installed at the nuclear power plant.

  The system configuration of the gas waste treatment system will be described with reference to FIG. The exhaust gas generated from the nuclear reactor and driving the steam turbine 1 is partially returned to water by the condenser 2 and then heated to the recombination temperature of hydrogen molecules and oxygen molecules by the exhaust gas preheater 3. .

  Next, after the exhaust gas is converted into steam by the recombination reaction in the exhaust gas recombiner 4, the heat of the steam is removed by the exhaust gas condenser 5, and then dehumidified by the dehumidifying cooler 6. The dehumidified exhaust gas is stored outside the power plant through the exhaust pipe 8 after the radioactive gas waste in the exhaust gas is retained for a predetermined time by the activated carbon in the activated carbon type rare gas holdup tower 7 to reduce the concentration of the radioactive gas waste. Exhausted.

  In this system, in order to confirm the soundness of the coupling performance in the exhaust gas recombiner 4 using a catalytic reaction, a sampling line 9 is provided as a piping system for sampling gas B from the exhaust gas downstream of the exhaust gas recombiner 4, A hydrogen concentration meter 11 for measuring the hydrogen concentration in the collected sampling gas B is provided downstream of the sampling line 9 via an inlet valve 13 and a dehumidifier 16.

  The sampling gas B used for measurement by the hydrogen concentration meter 11 is discharged from the outlet valve 14 and then returned to the outlet side of the condenser 2. In order to remove the condensed water generated in the sampling line 9, a drain pot 12 branched from the sampling line 9 is installed via a dehumidifier 16, and the condensed water stored in the drain pot 12 is drain valve 15. Is discharged from the sampling line 9 and returned to the condenser 2.

  As a hydrogen concentration meter of the hydrogen concentration measuring device, a heat conduction type hydrogen concentration meter is mainly used. The thermal conductivity type hydrogen concentration meter measures the hydrogen concentration by taking advantage of the fact that the thermal conductivity of hydrogen is higher than that of air. There is a problem that it cannot be measured.

  In the above-mentioned system, in the prior art, for example, as in Patent Document 1, a dehumidifying apparatus that removes moisture by incorporating a hollow fiber membrane having a large vapor permeability coefficient as a vapor permeable membrane in a radioactive gas waste treatment system of a nuclear power plant is incorporated. Proposed.

  Further, as a method for dehumidifying and drying exhaust gas, a dehumidifying device to which a vapor permeable membrane is applied as shown in Patent Document 2 is adopted, and a vapor absorbing liquid in which a substance that lowers the saturated vapor pressure is added to a fluid as a vapor permeable membrane side medium Has been proposed that lowers the saturated vapor pressure from the exhaust gas side.

  In addition, as shown in Patent Document 3, a hydrogen oxygen measuring device having a dehumidifier that cools sampling gas using cooling water on a sampling rack in a containment atmosphere monitor of a nuclear power plant has been proposed.

  In addition, as shown in Patent Document 4, in order to measure the hydrogen concentration of soil gas for earthquake prediction, etc., a drying tube filled with a desiccant is provided upstream of the semiconductor gas sensor to remove the moisture of the soil gas to be inspected. The structure to do is known.

JP-A-6-347593 JP-A-11-264984 JP 2000-2784 A JP-A-1-66554

  As described above, the hydrogen concentration meter used in the hydrogen concentration measuring apparatus of the gas waste treatment system cannot measure normally when moisture flows into the meter. For this reason, in the gas waste treatment system, a dehumidifying cooler is installed to remove moisture in the exhaust gas to prevent inflow of moisture into the hydrogen concentration meter.

  However, during the periodic inspection for inspecting the nuclear power plant, the exhaust gas sampling is not performed by the hydrogen concentration measuring device, and a gas containing moisture stays in the piping of the sampling line. The sampling line is in contact with the atmosphere inside the reactor, and when the atmospheric temperature changes, condensation occurs in the sampling line from the outlet of the dehumidifying cooler to the hydrogen concentration meter, and moisture adheres to the piping. There is a possibility of flowing into the hydrogen concentration meter during service.

  Even if a dehumidifying device having a built-in hollow fiber membrane having a large vapor permeability coefficient is used as a vapor permeable membrane in a dehumidifying cooler for a gas waste treatment system as in Patent Document 1 and Patent Document 2, water drops on the hydrogen concentration meter Inflow cannot be completely prevented.

  Moreover, in the prior art which uses the dehumidifier which cools sampling gas using cooling water like patent document 3, it is a hydrogen concentration meter with respect to the condensed water which generate | occur | produces in the sampling line from a dehumidifier to a hydrogen concentration meter. The inflow to can not be prevented. In addition, it is necessary to secure power supply and cooling water for the operation of the dehumidifier, but the dehumidifier cannot be operated during the periodic inspection due to the inspection of the equipment. Inflow cannot be prevented.

  Moreover, when using the drying pipe | tube with which the desiccant was enclosed like patent document 4, if a desiccant is saturated, dehumidification performance will fall rapidly.

  Accordingly, an object of the present invention is to provide a hydrogen concentration measuring apparatus that reliably prevents the inflow of moisture into a hydrogen concentration meter and continuously and accurately measures the hydrogen concentration.

  The present invention relates to a boiling water reactor, a steam turbine, a sampling line for collecting sampling gas from exhaust gas of a gas waste treatment system of a nuclear power plant equipped with a gas waste treatment system having an exhaust gas recombiner, and In a reactor exhaust gas hydrogen concentration measurement device having a hydrogen concentration meter provided in the sampling line, a dryer that reduces the moisture of the sampling gas upstream of the hydrogen concentration meter in the sampling line and prevents the flow into the hydrogen concentration meter Is provided.

  In the apparatus for measuring hydrogen concentration in reactor exhaust gas, the humidity of the sampling gas whose moisture has been reduced by a dryer is set to about 1% to 10%.

  In the apparatus for measuring hydrogen concentration in reactor exhaust gas, the dryer uses a hollow fiber membrane as a filter material.

  In the apparatus for measuring the hydrogen concentration in the reactor exhaust gas, the sampling line is provided with a pipe warming heater for preventing moisture condensation in the sampling line pipe.

  Moreover, in the hydrogen concentration measuring device for nuclear reactor exhaust gas, the set temperature of the pipe heat-retaining heater is about 40 degrees or more.

  In addition, in the reactor exhaust gas hydrogen concentration measurement device, a dry air line that allows dry air to flow upstream of the dryer of the sampling line and a dry air tank are connected to dry the moisture in the sampling line before the operation of the reactor. It is characterized by.

  Furthermore, in the reactor exhaust gas hydrogen concentration measurement device, an inlet motor valve and an outlet motor valve are provided at the inlet and outlet of the sampling line dryer and hydrogen concentration meter, respectively, and the opening and closing of the inlet motor valve and the outlet motor valve are controlled. An interlock control device and a power source are provided, and the interlock control device performs interlock control for opening the outlet motor valve after opening the inlet motor valve.

  Furthermore, in the apparatus for measuring the hydrogen concentration of the reactor exhaust gas, a pressure indicating switch and an inlet motor valve are provided upstream of the dryer and the hydrogen concentration meter of the sampling line, and an interlock control device and a power source for controlling the pressure indicator switch and the inlet motor valve The interlock control device performs interlock control for opening the inlet motor-operated valve when the pressure measured by the pressure indication switch becomes equal to or lower than a set value.

  The present invention relates to a boiling water reactor, a steam turbine, a sampling line for collecting sampling gas from exhaust gas of a gas waste treatment system of a nuclear power plant equipped with a gas waste treatment system having an exhaust gas recombiner, and In a reactor exhaust gas hydrogen concentration measurement device having a hydrogen concentration meter provided in the sampling line, a dryer that reduces the moisture of the sampling gas upstream of the hydrogen concentration meter in the sampling line and prevents the flow into the hydrogen concentration meter By providing this, it is possible to reliably prevent moisture generated in the sampling line from flowing into the hydrogen concentration meter during regular inspections as well as during operation of the nuclear power plant, and thus a continuous and highly accurate hydrogen concentration measuring device. Can be realized.

It is a systematic diagram of the hydrogen concentration measuring apparatus by Example 1 of this invention. It is a systematic diagram of the hydrogen concentration measuring apparatus by Example 2 of this invention. It is a systematic diagram of the hydrogen concentration measuring apparatus by Example 3 of this invention. It is a systematic diagram of the hydrogen concentration measuring apparatus by Example 4 of this invention. It is a systematic diagram of the hydrogen concentration measuring apparatus by Example 5 of this invention. It is a systematic diagram of the hydrogen concentration measuring apparatus in a prior art.

  Hereinafter, the present invention will be described with reference to examples and drawings.

  Embodiment 1 of the present invention will be described below with reference to FIG. In the following drawings, the description of the same components as those in FIG. 6 described in the background art is omitted.

  In the first embodiment, the sampling gas B is collected from the sampling line 9 connected to the subsequent stage of the dehumidifying cooler 6 and taken into the hydrogen concentration meter 11 through the inlet valve 13 of the hydrogen concentration measuring device. Further, the humidity in the sampling gas B is reduced by the dehumidifier 16 while passing through the sampling line 9.

  Next, after the sampling gas B is further dried by the dryer 10 installed downstream of the dehumidifier 16, the hydrogen concentration in the sampling gas B is measured by the subsequent hydrogen concentration meter 11.

  The sampling gas B used for the measurement is discharged from the outlet valve 14 of the hydrogen concentration measuring device and then returned to the outlet side of the condenser 2. In order to remove the condensed water generated in the sampling line 9, a drain pot 12 branched from the sampling line 9 is installed downstream of the dryer 16, and the condensed water collected in the drain pot 12 is drain valve 15. Is returned to the condenser 2.

  In the first embodiment, the dryer 10 is installed on the sampling line 9 upstream of the hydrogen concentration meter 11. As a result, when the performance of the dehumidifying cooler 6 is insufficient and moisture-containing gas flows into the sampling line 9, moisture condensed in the sampling line 9 during periodic plant inspection flows into the hydrogen concentration meter 11 at the start of in-service. Even in this case, the moisture is removed by the dryer 10 and the inflow of moisture to the hydrogen concentration meter 11 is reliably blocked.

  The humidity of the sampling gas B after passing through the dryer 10 is reduced to about 1 to 10%. Therefore, the measurement can be performed in a state where the dried sampling gas B constantly flows into the hydrogen concentration meter 11, and the sampling gas B can be provided without sacrificing the continuity of measurement and the correction accuracy of the hydrogen concentration meter 11.

  The dryer 10 uses a dryer using a hollow fiber membrane as a filter material. This dryer does not require a power source, and it is possible to prevent moisture generated in the sampling line 9 from flowing into the hydrogen concentration meter 11 when maintenance work is performed with the main power turned off during a periodic inspection of a nuclear power plant. These moisture can be removed later in service.

  Next, Example 2 of the present invention will be described with reference to FIG. In the following drawings, the description of the same components as those in the first embodiment is omitted.

  In FIG. 2, a plurality of pipe heat insulation heaters 17 for preventing condensation are installed on the outer circumference of the sampling line 9 at appropriate intervals. Considering that the ambient temperature of the hydrogen concentration meter 11 is about 40 ° C., the set temperature of the pipe heat insulation heater 17 is set to 40 ° C. or higher, which is higher than the expected ambient temperature. The re-sampling gas B is kept at 40 ° C. or higher by keeping the temperature of the water, and moisture condensation in the sampling line 9 is prevented.

  According to the second embodiment, it is possible to reliably reduce the amount of moisture flowing into the dryer 10, and not only can provide an accurate measurement function without sacrificing measurement continuity and correction accuracy, but also the dryer. It is possible to further improve the maintainability, for example, by extending the device replacement time due to performance degradation.

  Next, Embodiment 3 of the present invention will be described with reference to FIG. In FIG. 3, a drying line 18 and a dry air tank AC for flowing dry air for drying the piping are newly installed upstream of the hydrogen concentration meter 11. Before flowing the sampling gas B into the hydrogen concentration meter 11, the dry air in the dry air tank AC flows into the sampling line 9 from the drying line 18 and is blown until the piping is dried, so that the moisture in the sampling line 9 piping is Allow to dry completely.

  According to the third embodiment, it is possible to surely prevent the performance of the dryer 10 from being deteriorated, and it is possible to extend the equipment replacement time due to the performance deterioration of the dryer 10. An accurate measurement function can be provided without sacrificing the continuity of measurement and the accuracy of correction.

  Next, Embodiment 4 of the present invention will be described with reference to FIG. In FIG. 4, an inlet motor operated valve 19 and an outlet motor operated valve 20 are installed at the inlet and outlet of the sampling line, respectively.

  In addition, the inlet motor-operated valve 19 and the outlet motor-operated valve 20 are controlled by performing interlock control in which the outlet motor-operated valve 20 is opened after the inlet motor-operated valve 19 is opened. An interlock control device ILC is provided. PS is a maintenance power source for driving the inlet motor operated valve 19, the outlet motor operated valve 20, and the interlock control device ILC.

  Here, since the outlet side of the condenser 2 which is the return destination of the sampling gas B has a pressure close to vacuum, when the outlet motor-operated valve 20 is opened while the inlet motor-operated valve 19 is closed, there is a difference. Due to the pressure, the water in the drain pot 12 flows into the hydrogen concentration meter 11 via the sampling line 9 and accurate measurement cannot be performed.

  According to the fourth embodiment, it is possible to realize stable hydrogen concentration measurement by suppressing a sudden decrease in the pressure of the hydrogen concentration meter 11 and preventing water from flowing into the hydrogen concentration meter 11. .

  Next, Embodiment 5 of the present invention will be described with reference to FIG. In FIG. 5, a pressure indicating switch 21 is installed on the upstream side of the hydrogen concentration meter 11 in the sampling line 9, and an inlet electric valve 22 for the hydrogen concentration meter is provided on the upstream side of the pressure indicating switch 21. The inlet motor-operated valve 22 is an electrically operated on / off valve having an interlock control having a control logic that is opened when the pressure measured by the pressure indicating switch becomes a predetermined value or less. Interlock control of the pressure indicating switch 21 and the inlet motor operated valve 22 is executed by the interlock control device ILC and the maintenance power source PS as in the fourth embodiment.

  When a rapid pressure drop occurs, the inflow of water from the drain pot 12 to the hydrogen concentration meter 11 occurs as described in the fourth embodiment. In the fifth embodiment, the pressure indication switch 21 and the inlet motor-operated valve 22 are provided to notify the operator of the abnormality as soon as possible, and the sudden pressure drop is prevented by the interlock control device ILC so that the water droplets flow into the hydrogen concentration meter 11. By preventing this automatically, instrument failure can be reliably prevented.

1: Steam turbine 2: Condenser 3: Exhaust gas preheater 4: Exhaust gas recombiner 5: Exhaust gas condenser 6: Dehumidifier cooler 7: Rare gas holdup tower 8: Exhaust tube 9: Sampling line 10: Dryer 11: Hydrogen concentration meter 12: Drain pot 13: Inlet valve 14: Outlet valve 15: Drain valve 16: Dehumidifier 17: Piping warmer heater 18: Drying line 19: Inlet motor valve 20: Outlet motor valve 21: Pressure indication switch 22 : Motor inlet A: Steam B: Sampling gas AT: Dry air tank ILC: Interlock controller PS: Power supply for maintenance

Claims (2)

A sampling line for sampling gas from the exhaust gas of the gas waste treatment system of a nuclear power plant equipped with a boiling water reactor, a steam turbine, and a gas waste treatment system having an exhaust gas recombiner, and the sampling In the hydrogen concentration measuring device for reactor exhaust gas having a hydrogen concentration meter installed in the line,
Provided upstream of the hydrogen concentration meter in the sampling line is a dryer that reduces the moisture of the sampling gas and prevents inflow into the hydrogen concentration meter, and the dryer of the sampling line and the inlet of the hydrogen concentration meter An inlet motor-operated valve and an outlet motor-operated valve, respectively, and an interlock control device and a power source for controlling the opening and closing of the inlet motor-operated valve and the outlet motor-operated valve. A hydrogen concentration measuring device for reactor exhaust gas, wherein interlock control is performed to open the outlet motor valve after opening the valve. A sampling line for sampling gas from the exhaust gas of the gas waste treatment system of a nuclear power plant equipped with a boiling water reactor, a steam turbine, and a gas waste treatment system having an exhaust gas recombiner, and the sampling In the hydrogen concentration measuring device for reactor exhaust gas having a hydrogen concentration meter installed in the line,
A dryer for reducing the moisture of the sampling gas and preventing inflow into the hydrogen concentration meter is provided upstream of the hydrogen concentration meter in the sampling line, and upstream of the dryer and hydrogen concentration meter in the sampling line. A pressure indicating switch and an inlet motor operated valve are provided, and an interlock control device and a power source for controlling the pressure indicating switch and the inlet motor operated valve are provided, and the pressure measured by the pressure indicating switch by the interlock control device is a set value. An apparatus for measuring a hydrogen concentration in a reactor exhaust gas, wherein an interlock control is performed to open the inlet motor valve when:

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