JP2011179992A - Exhaust gas recombiner and method for measuring temperature of catalyst used for it - Google Patents

Abstract

An exhaust gas recombiner capable of monitoring the temperature of a metal catalyst filled therein is provided in an exhaust gas recombiner of a gas waste treatment system installed in a nuclear power plant or the like.
In an exhaust gas recombiner with a built-in metal catalyst, a thermometer well with a built-in thermocouple is installed inside the exhaust gas recombiner to monitor the temperature of the metal catalyst around the thermocouple. As a result, the recombination performance of the metal catalyst is monitored, and the life and replacement period of the metal catalyst are grasped.
[Selection] Figure 1

Description

  The present invention relates to an exhaust gas recombiner in a gas waste treatment system installed in a nuclear power plant and the like, and a temperature measurement method for a metal catalyst filled therein.

  The exhaust gas recombiner is used in, for example, a gas waste treatment system installed in a nuclear power plant as described in Patent Document 1, and has a built-in metal catalyst. In the nuclear power plant, radiation irradiation is performed. It is installed to recombine oxygen and hydrogen generated by decomposition from water vapor by catalytic action.

  It is known that the recombination performance of a metal catalyst decreases due to the deterioration of the catalyst over time or the poisoning of the catalyst poisonous substance. For example, as described in Patent Document 2 and Patent Document 3, It is known that when the recombination performance is lowered, the heat of reaction between oxygen and hydrogen generated from the metal catalyst is reduced, and the ambient temperature in the vicinity of the metal catalyst and the catalyst is lowered.

  In Patent Document 4, a plurality of temperature sensors are provided at the entrance, exit and inside of the reaction zone. Furthermore, as shown in Patent Document 5, an example in which a temperature sensor is inserted into a honeycomb-shaped catalyst layer is disclosed.

JP 2005-55270 A Japanese Utility Model Publication No. 62-61919 JP-A-9-166015 JP 2009-216707 A JP 2001-310114 A

  In a nuclear power plant, the recombination performance of oxygen and hydrogen decreases due to the aging of the metal catalyst installed inside the exhaust gas recombiner or the influence of catalyst poisons, etc., and the exhaust gas containing hydrogen is discharged into the exhaust gas recombiner. If the recombination reaction cannot be achieved sufficiently when passing through, the hydrogen concentration at the downstream outlet increases. If the hydrogen concentration increases during operation, hydrogen combustion may occur, and the operation of the power plant is stopped for safety reasons. For this reason, it is extremely important to grasp the decrease in recombination performance during operation of the metal catalyst installed inside the exhaust gas recombiner.

  Conventional exhaust gas recombiners are equipped with a thermometer at the exhaust gas outlet side pipe, monitoring the reaction heat accompanying the recombination reaction of hydrogen and oxygen by the catalyst from the exhaust gas temperature, and monitoring the deterioration of the recombination performance of the metal catalyst. Yes. However, in the above configuration, there is a possibility that the hydrogen concentration has already increased at the time when the temperature drop of the exhaust gas is detected. For this reason, it is effective to monitor the temperature of the catalyst or the vicinity of the catalyst in the upstream part of the reaction system in order to grasp the catalyst deterioration state in advance before the catalyst is completely deteriorated.

  However, it has been difficult to directly measure the temperature of the metal catalyst installed inside the exhaust gas recombiner with the exhaust gas recombiner using the metal catalyst so far. The exhaust gas recombiner uses a double structure that accommodates the metal catalyst by installing a cartridge in the container in consideration of the metal catalyst replacement workability at the time of maintenance, and inserting a thermometer in an arbitrary area is structurally There was a problem that there was a limitation and the performance status of the metal catalyst could not be easily grasped.

  In order to solve the above-described problems, the present invention provides an exhaust gas recombiner of a gas waste treatment system having a cartridge filled with a metal catalyst that feeds exhaust gas into the interior, and a plurality of measurement regions for the metal catalyst in the cartridge. A plurality of temperature sensors for detecting the reaction temperature are provided.

  Further, the plurality of measurement areas in which the temperature sensor is installed are different measurement areas in the exhaust gas feeding direction of the metal catalyst in the cartridge.

  The temperature sensor is held for each of the plurality of measurement regions for detecting the temperature in a thermometer well inserted in the exhaust gas feeding direction in the metal catalyst of the cartridge.

  Further, the thermometer well is characterized by having confidentiality against exhaust gas.

  Further, the temperature sensor is constituted by a thermocouple.

  The thermometer well has a plurality of spacer blocks, and the ambient temperature of the metal catalyst in each spacer block installation measurement region is measured by the thermocouple held by each spacer block.

  In addition, a leak prevention plate is provided between the thermometer well and the metal catalyst to prevent leakage of exhaust gas from the gap.

  The thermometer well is supported by a nozzle provided in a lower pipe of the exhaust gas recombiner, and is supported by a nozzle provided on an upper end plate of the exhaust gas recombiner.

  In addition, a plurality of thermometer wells are pressed from the side surface of the exhaust gas recombiner to each measurement region in the exhaust gas feeding direction on the outer surface of the cartridge. The thermometer well has an axially flexible bellows at least in part.

  Further, a gas waste treatment system having a cartridge filled with a metal catalyst for feeding exhaust gas inside, and having a plurality of temperature sensors for detecting reaction temperatures in a plurality of measurement regions in the exhaust gas feeding direction of the metal catalyst. In the exhaust gas recombiner temperature control method, the temperature of each measurement region is measured, and warning information indicating the deterioration of the metal catalyst in each measurement region is output when the temperature of each measurement region falls below a predetermined threshold value. Features.

  According to the present invention, the ambient temperature in an arbitrary region of the metal catalyst installed in the exhaust gas recombiner can be measured by the temperature sensor inserted in the metal catalyst cartridge. This makes it possible to constantly monitor changes in the heat of reaction generated from the metal catalyst as a result of the recombination reaction between oxygen and hydrogen, and immediately detects signs of deterioration of the recombination performance due to aging of the metal catalyst or catalyst poisoning in the reaction region. Thus, it is possible to quickly and accurately grasp the life and replacement period of the metal catalyst and appropriately cope with it.

It is sectional drawing which shows the exhaust gas recombiner by the 1st Embodiment of this invention. It is the A section expanded sectional view of FIG. It is a fragmentary sectional view which shows the exhaust gas leak prevention structure in the metal catalyst of this invention. It is a schematic diagram which shows the detail of the temperature well of 1st Embodiment. It is a graph which shows the temperature change of the metal catalyst in the measurement area | region (a) (b) (c) of FIG. It is sectional drawing which shows the exhaust gas recombiner by the 2nd Embodiment of this invention. It is the B section expanded sectional view of FIG. It is sectional drawing which shows the exhaust gas recombiner by the 3rd Embodiment of this invention. It is the C section expanded sectional view of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[First Embodiment]
In FIG. 1, an exhaust gas recombiner 1 is used in a gas waste treatment system installed in a nuclear power plant, and is composed of a vertical cylindrical pressure vessel. The fluid flowing in the exhaust gas recombiner 1 is exhaust gas composed of oxygen, hydrogen, water vapor, and the like. Inside the exhaust gas recombiner 1, there is provided a cartridge 3 for storing a metal catalyst 2 provided for recombining oxygen and hydrogen generated by partial decomposition of water vapor. Reference numeral 4 denotes an inlet of the exhaust gas recombiner 1.

  The metal catalyst 2 is formed by laminating a catalyst having a thin plate structure in which an activated metal (Pt, Pd, etc.) that promotes the binding of hydrogen and oxygen on a porous alumina base material is formed in the cartridge 3 of the exhaust gas recombiner 1. Has a structure.

  As shown in FIG. 2, a pipe base 7 is installed in the lower pipe 6 of the exhaust gas recombiner 1, and a thermometer arranged so as to penetrate through the hole provided in the central part of the metal catalyst layer and the cartridge bottom plate. The well 8 is held by the nozzle 7. In order to insert the thermometer well 8, a hole 5 is provided in the center of each metal catalyst 2 and a hole 6 is provided in the center of the bottom plate of the cartridge 3 as shown in FIG. The thermometer well 8 is provided with a disk-shaped leak prevention member 14 for each layer of the metal catalyst 2 to prevent leakage of exhaust gas from the gap between the hole 5 of the metal catalyst 2 and the thermometer well 8.

  As shown in FIG. 4, a plurality of spacer blocks 10 made of a material having good thermal conductivity such as metal are arranged inside the thermometer well 8, and each spacer block 10 is accommodated in a guide tube 11. A thermocouple 12 is attached. In order to prevent a bypass leak in which unreacted hydrogen gas flows through the inside of the thermometer well 8, a cap 12 is attached to the upper end of the thermometer well 8 to maintain airtightness.

  The guide tube 11 attached to the upper spacer block 10 passes through the lower spacer block 10 and is held by the upper spacer block 10. In the thermocouple 12 that measures the ambient temperature of the metal catalyst 2, the temperature detection part at the tip of the thermocouple 12 is held and fixed to each spacer block 10 to detect the ambient temperature. With this configuration, the reaction heat generated from the metal catalyst 2 is transmitted to the thermocouple 12 fixed to the spacer block 10 via the thermometer well 8, and the ambient temperature of the metal catalyst 2 is measured. The measurement data is processed by a control device (not shown) and used for system control.

  By installing each spacer block 10 in an arbitrary area, the ambient temperature of the metal catalyst 2 in an arbitrary area can be measured, and thereby the recombiner performance can be monitored over the entire metal catalyst.

  FIG. 5 is a graph showing the measurement state of the ambient temperature of the metal catalyst in the regions (a), (b), and (c) of FIG. The long time axis corresponding to the life of the metal catalyst is taken on the horizontal axis, and the temperature due to the heat of reaction of the metal catalyst is taken on the vertical axis. In the temperature curve (a) corresponding to the region (a), the reaction is continued at, for example, 320 ° C. under a predetermined condition, and the reaction temperature gradually decreases due to deterioration of the metal catalyst. As the temperature curve (b) and the temperature curve (c) sequentially deteriorate, the deterioration of the metal catalyst proceeds. These data are constantly monitored by the control device and transmitted to the operator through a display or the like as necessary. When the reaction temperature decreases to, for example, 300 ° C. in each temperature curve, it is determined that the metal catalyst 2 in each temperature region has deteriorated, and the cartridge 3 is replaced. At this time, warning information such as a warning light, a warning display, a warning sound, and the like can be output to prompt replacement of the metal catalyst 2.

According to this, the cartridge 3 can be reliably replaced before the metal catalyst 2 is completely deteriorated and the hydrogen gas is discharged, so that the exhaust gas recombiner 1 can be used safely. The metal catalyst 2 is composed of, for example, about 40 catalyst layers. The 10th layer from the top is set as a region (a), the 20th layer is set as a region (b), and the 30th layer is set as a region (c). Measure.
[Second Embodiment]
FIG. 6 is a cross-sectional view showing the overall configuration of the exhaust gas recombiner according to the second embodiment of the present invention, and FIG. It is sectional drawing.

  In the exhaust gas recombiner 20 according to the present embodiment, a hole 22 is provided in the metal catalyst 21, and a hole 24 is provided at the bottom of the cartridge 23. Further, a nozzle 26 is installed on the upper end plate 25 of the exhaust gas recombiner 20, and a thermometer well 27 disposed so as to penetrate the metal catalyst 21 and the holes 22 and 24 provided in the bottom of the cartridge. Is held by the nozzle 26. The leak prevention structure for the exhaust gas on the side surface of the thermometer well 27 is the same as that of the first embodiment.

With the configuration described above, the ambient temperature of the metal catalyst in an arbitrary region can be measured as in the first embodiment, and thereby the recombination performance of the metal catalyst in an arbitrary region can be monitored.
[Third Embodiment]
FIG. 8 is a cross-sectional view showing the overall configuration of the exhaust gas recombiner according to the third embodiment of the present invention, and FIG. It is.

  In the present embodiment, the body plate 31 of the exhaust gas recombiner 30 has a through hole 32, and a seat 33 for attaching a thermometer well is provided in the through hole 32. A thermocouple 35 is attached to the tip of the thermometer well 34 from the inside of the tube, and the outside is in contact with the cartridge 36. Moreover, the termination | terminus is made into the tubular structure which has the seat for attachment.

  Further, a part of the thermometer well 34 is a bellows 37 whose well length can be expanded and contracted to absorb the thermal expansion of the constituent members accompanying the high temperature heat generation during the operation of the exhaust gas recombiner 30. The thermometer well 34 is inserted into the through hole 32 of the exhaust gas recombiner body plate 31 from the tip, and is fixed to the seat 33 in a state where the tip is in close contact with the outer surface of the cartridge 36 fixed inside the exhaust gas recombiner 30. Is done.

  With the above configuration, even when the cartridge 36 installed in the exhaust gas recombiner 30 is thermally expanded, the tip of the thermometer well 34 is in close contact with the outer surface of the cartridge 36, and the metal catalyst 38 filled in the cartridge 36. The change in the reaction heat of oxygen and hydrogen generated from the gas can be measured and monitored by the thermocouple 35 in the thermometer well 34 through the outer surface of the cartridge 36 and the tip of the thermometer well 34. Thereby, the recombination performance of the metal catalyst filled in the exhaust gas recombiner can be grasped.

1, 20, 30: Exhaust gas recombiner 2: Metal catalyst 3, 23, 36: Cartridge 6: Lower piping 8, 27, 34: Thermometer well 10: Spacer block 11: Guide tube 12, 35: Thermocouple 14: Leak prevention plate 25: Upper end plate 37: Bellows

Claims (12)

  In an exhaust gas recombiner of a gas waste treatment system having a cartridge filled with a metal catalyst for feeding exhaust gas inside, a plurality of temperature sensors are provided for detecting reaction temperatures in a plurality of measurement regions of the metal catalyst in the cartridge. An exhaust gas recombiner characterized by that.   2. The exhaust gas recombiner according to claim 1, wherein the plurality of measurement regions in which the temperature sensor is installed are different measurement regions in the exhaust gas feeding direction of the metal catalyst in the cartridge.   3. The exhaust gas recirculation device according to claim 1, wherein the temperature sensor is held for each of the plurality of measurement regions for detecting the temperature in a thermometer well inserted in the metal catalyst of the cartridge in the exhaust gas feeding direction. Combiner.   4. The exhaust gas recombiner according to claim 3, wherein the thermometer well has confidentiality with respect to the exhaust gas.   The exhaust gas recombiner according to any one of claims 1 to 4, wherein the temperature sensor is constituted by a thermocouple.   6. The exhaust gas recycle according to claim 5, wherein the thermometer well has a plurality of spacer blocks, and the temperature of the metal catalyst in each spacer block installation measurement region is measured by the thermocouple held by each spacer block. Combiner.   The exhaust gas recombiner according to claim 3, wherein a leak prevention plate for preventing leakage of exhaust gas from a gap is provided between the thermometer well and the metal catalyst.   4. The exhaust gas recombiner according to claim 3, wherein the thermometer well is supported by a nozzle provided in a lower pipe of the exhaust gas recombiner.   4. The exhaust gas recombiner according to claim 3, wherein the thermometer well is supported by a nozzle provided on an upper end plate of the exhaust gas recombiner.   3. The exhaust gas recombiner according to claim 1, wherein a plurality of thermometer wells are pressed from a side surface of the exhaust gas recombiner to each measurement region in the exhaust gas feeding direction on the outer surface of the cartridge.   11. The exhaust gas recombiner according to claim 10, wherein the thermometer well has a bellows having axial flexibility in at least a part thereof. An exhaust gas recycle system for a gas waste treatment system having a cartridge filled with a metal catalyst for feeding exhaust gas inside and having a plurality of temperature sensors for detecting reaction temperatures in a plurality of measurement regions in the exhaust gas feed direction of the metal catalyst. In the temperature control method of the coupler,
The catalyst temperature of the exhaust gas recombiner is characterized by measuring the temperature of each measurement region and outputting warning information indicating the deterioration of the metal catalyst in each measurement region when the temperature of each measurement region falls below a predetermined threshold value Measuring method.

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