JP2011196963A - Gaseous waste treatment system and method of operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gaseous waste treatment system for improving recombination performance of an off-gas recombiner without providing any dedicated blowers on an off-gas recirculation line.SOLUTION: The gaseous waste treatment system includes, in an off-gas channel from a steam capacitor, an air ejector, the off-gas recombiner, an off-gas steam capacitor, a rare gas holdup device, and a stack. The gaseous waste treatment system also includes an off-gas recirculation line branched from an exit side of the off-gas steam capacitor and disposed to return one portion of off-gas through the off-gas steam capacitor to the off-gas channel between the steam capacitor and the air ejector, a flow regulating valve installed in the off-gas recirculation line, a hydrogen concentration detector for detecting hydrogen concentration of off-gas flowing in the off-gas channel at a downstream side of the off-gas steam capacitor, and a control unit for regulating the flow regulating valve based on the hydrogen concentration of the off-gas detected by the hydrogen concentration detector, thus circulating the off-gas to the off-gas recombiner through the off-gas recirculation line with the air ejector as a drive source.

Description

  The present invention relates to a gas waste treatment facility for removing or treating gas waste in a boiling water nuclear power plant and a method for operating the gas waste treatment facility.

  As an exhaust gas recirculation operation method for a gas waste treatment facility for removing or treating gaseous waste in a boiling water nuclear power plant, Japanese Patent Laid-Open No. 10-260296 discloses a part of exhaust gas from the outlet side of an exhaust gas recombiner. A recirculation line that is branched and supplied to the inlet side of the exhaust gas recombiner is disposed, and provided in the recirculation line when the hydrogen concentration of the exhaust gas on the outlet side of the exhaust gas recombiner exceeds a predetermined value. A technique for operating a gas waste treatment facility configured to circulate a part of the exhaust gas that has passed through the exhaust gas recombiner through the recirculation line to the exhaust gas recombiner by opening a valve is disclosed.

  Japanese Patent Application Laid-Open No. 2004-69572 has a recirculation line that branches a part of the exhaust gas from the outlet side of the exhaust gas condenser installed downstream of the exhaust gas recombiner and releases it to the main condenser. The process pressure from the exhaust gas condenser outlet to the rare gas hold-up device is measured so that the process pressure at the exhaust gas condenser outlet side is maintained at a predetermined value, and the measured process pressure is maintained at a desired pressure. A technique is disclosed in which the opening of a valve provided in the recirculation line is adjusted so that a part of the exhaust gas that has passed through the exhaust gas condenser is released to the main condenser through the recirculation line.

JP-A-10-260296 JP 2004-69572 A

  However, in the technique described in Japanese Patent Laid-Open No. 10-260296, the exhaust gas recirculation line causes the exhaust gas flowing through the exhaust gas recirculation line to return from the outlet side of the exhaust gas recombiner to the inlet side of the exhaust gas recombiner. In order to recycle the exhaust gas to the exhaust gas recombiner through the exhaust gas recirculation line in order to improve the recombination performance of the exhaust gas recombiner, a dedicated blower for forcibly supplying the exhaust gas is provided. Has to be provided on the exhaust gas recirculation line, and there is a problem that the equipment structure becomes complicated and the equipment cost for installing the blower is required.

  Further, in the technique described in Japanese Patent Application Laid-Open No. 2004-69572, in order to keep the process pressure from the exhaust gas condenser outlet to the rare gas hold-up device at a predetermined value, the outlet side of the exhaust gas condenser through the recirculation line. A part of the exhaust gas is branched and released to the main condenser, which is not directly related to the technology for improving the recombination performance of the exhaust gas recombiner.

  The object of the present invention is to adjust the flow rate of the recirculation line so that the hydrogen concentration in the exhaust gas becomes a desired value without installing a dedicated blower for supplying the exhaust gas to the exhaust gas recirculation line. Another object of the present invention is to provide a gas waste treatment facility and a method for operating the gas waste treatment facility that can improve the recombination performance.

  The gas waste treatment facility of the present invention is configured to supply gas waste to the exhaust gas flow path for flowing down the water vapor and the gas waste supplied from the condenser that condenses the water vapor generated in the nuclear reactor using the water vapor as a driving source. An air extractor for extraction, an exhaust gas recombiner for treating gaseous waste extracted by the air extractor, an exhaust gas condenser for condensing water vapor in the exhaust gas flowing down from the exhaust gas recombiner, and an exhaust gas condensate Exhaust gas condensate in a gas waste treatment facility equipped with a noble gas holdup device for treating radioactive noble gas in exhaust gas flowing down the vessel and an exhaust cylinder for discharging the exhaust gas flowing down the noble gas holdup device out of the system An exhaust gas recirculation line arranged to return from the exhaust gas outlet to the exhaust gas flow path between the condenser and the air extractor to return a part of the exhaust gas through the exhaust gas condenser. Installed in the line A flow control valve that adjusts the flow rate of the exhaust gas flowing through the gas recirculation line, a hydrogen concentration detector that detects the hydrogen concentration of the exhaust gas flowing through the exhaust gas flow path downstream of the exhaust gas condenser, and the hydrogen concentration detector And a control device for adjusting the flow rate control valve based on the hydrogen concentration of the exhaust gas, wherein the exhaust gas is circulated to the exhaust gas recombiner through the exhaust gas recirculation line using the air extractor as a drive source. .

  The operation method of the gas waste treatment facility of the present invention is the method in which water vapor generated in a nuclear reactor is condensed in a condenser, and the gas waste flowed down from the condenser through an exhaust gas flow path is steam-driven air. The gaseous waste extracted by the extractor and extracted by the air extractor is treated by the exhaust gas recombiner, and the water vapor in the exhaust gas flowing down from the exhaust gas recombiner is condensed by the exhaust gas condenser, and the exhaust gas condensate is recovered. In the operation method of the gas waste treatment facility, the radioactive noble gas in the exhaust gas flowing down the water device is treated by a rare gas holdup device, and the exhaust gas flowing down the rare gas holdup device is discharged out of the system by an exhaust pipe. The exhaust gas passes through an exhaust gas recirculation line that is branched from the outlet side of the exhaust gas condenser and connected to an exhaust gas flow path between the condenser and the air extractor. A part of the exhaust gas flowing down the water device is returned to the upstream side of the air extractor, and the flow rate of the exhaust gas flowing through the exhaust gas recirculation line is adjusted based on the hydrogen concentration of the exhaust gas that has passed through the exhaust gas condenser, The exhaust gas is circulated to the exhaust gas recombiner through the exhaust gas recirculation line using the air extractor as a driving source.

  According to the present invention, the exhaust gas recombiner is adjusted by adjusting the flow rate of the recirculation line so that the hydrogen concentration in the exhaust gas becomes a desired value without installing a dedicated blower for supplying exhaust gas to the exhaust gas recirculation line. It is possible to realize a gas waste treatment facility and a method for operating the gas waste treatment facility that can improve the recombination performance.

FIG. 1 is a configuration diagram showing a gas waste treatment facility of a boiling water nuclear power plant that is an embodiment of the present invention.

  A gas waste treatment facility for removing or treating gas waste in a boiling water nuclear power plant that is an embodiment of the present invention and a method for operating the gas waste treatment facility will be described below with reference to the drawings.

  A gas waste treatment facility and a method for operating the gas waste treatment facility of a boiling water nuclear power plant according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 shows a schematic configuration of a boiling water nuclear power plant according to the present embodiment. Steam generated in a nuclear reactor 1 is composed of hydrogen gas, oxygen gas and It is supplied to the condenser 2 together with the rare gas gaseous waste and cooled, and the steam becomes condensate and is returned to the reactor 1 again.

  The exhaust gas containing hydrogen gas, oxygen gas, and rare gas gaseous waste flowing into the condenser 2 flows down from the condenser 2 through the exhaust gas system 15 and is supplied to the gaseous waste treatment facility 20.

  An air extractor 3 is installed in the exhaust gas system 15 located downstream of the condenser 2 and upstream of the gaseous waste treatment facility 20, and the exhaust gas is gasified from the condenser 2 through the exhaust gas system 15. It is configured to lead to the waste treatment facility 20.

  The gas waste treatment facility 20 is installed for the purpose of recombination of hydrogen and oxygen in the gas waste discharged from the nuclear reactor 1 and attenuation of radioactivity. Exhaust gas that is sequentially installed in the exhaust gas flow path 15 for flowing down the exhaust gas flowing in from the condenser 2 as a main device constituting the exhaust gas, and recombines (water) the hydrogen and oxygen in the exhaust gas into a non-flammable exhaust gas A recombiner 4, an exhaust gas condenser 5 installed downstream of the exhaust gas recombiner 4 to cool the water vapor in the exhaust gas flowing down the exhaust gas recombiner 4 to condensate, and the exhaust gas A rare gas hold-up device 9 that is disposed downstream of the condenser 5 and processes radioactive noble gas in the exhaust gas flowing down the exhaust gas condenser 5, and is disposed downstream of the rare gas hold-up device 9. The noble gas hold-up device 9 is Chimney 8 for discharging beat exhaust gas out of the system is provided.

From the reactor 1, hydrogen gas and oxygen gas generated by radiolysis of the reactor water, and by-products such as ³ H, ¹⁶ N, and ¹⁹ O are discharged as gas waste, and the reactor 1 Noble gases such as krypton (Kr) and xenon (Xe) are discharged as gaseous waste when radioactive material leaks from the fuel cladding tube. The exhaust gas recombiner 4 filled with a catalyst for recombining hydrogen and oxygen through the exhaust gas passage 15 via a main steam pipe (not shown), a condenser 2 and an air extractor 3 to be supplied. Introduced and processed.

  The exhaust gas recombiner 4 performs a process of recombining hydrogen and oxygen (water), and the gas discharged from the exhaust gas recombiner 4 is subjected to removal of water vapor in the gas by the exhaust gas condenser 5, and further, a rare gas. The gaseous waste in the gas is treated by the hold-up device 9 and finally released into the atmosphere by the exhaust pipe 8.

  As an apparatus constituting the gas waste treatment facility 20, an exhaust gas system 15 located between the outlet side of the exhaust gas condenser 5 and the inlet side of the air extractor 3 is branched from the exhaust gas system 15 and is An exhaust gas that is connected to an exhaust gas system 15 located between the downstream side of the condenser 2 and the upstream side of the air extractor 3 and circulates a part of the exhaust gas that has passed through the exhaust gas condenser 5 to the exhaust gas recombiner 4. A recirculation line 6 is provided, and a flow rate adjusting valve 7 for adjusting the flow rate of the exhaust gas flowing in the exhaust gas recirculation line 6 is provided on the exhaust gas recirculation line 6.

  An exhaust gas system 15 located between the outlet side of the exhaust gas condenser 5 and the inlet side of the air extractor 3 includes a hydrogen concentration detector 10 that measures the hydrogen concentration in the exhaust gas, and the hydrogen concentration detector. Based on the hydrogen concentration in the exhaust gas measured at 10, a control device 30 is installed to adjust the opening degree of the flow control valve 7 provided in the exhaust gas recirculation line 6.

The hydrogen concentration vo 1% (dry) in the exhaust gas at the outlet side of the exhaust gas condenser 5 is monitored by the hydrogen concentration detector 10, and the control device 30 is based on the hydrogen concentration of the exhaust gas detected by the hydrogen concentration detector 10. The flow rate of the flow rate regulating valve 7 of the exhaust gas recirculation line 6 is adjusted by adjusting the flow rate of exhaust gas to be circulated through the exhaust gas recirculation line 6 through the exhaust gas recirculation line 6 and detected by the hydrogen concentration detector 10. The hydrogen concentration of the exhaust gas is controlled to a desired value.
To do.

  That is, the detection signal of the hydrogen concentration of the exhaust gas detected by the hydrogen concentration detector 10 is input to the control device 30, and the control signal is used to adjust the flow rate of the command signal based on the comparison between the detected value of the hydrogen concentration and the set value. The flow rate of the exhaust gas that is output to the valve 7 and circulated to the exhaust gas recombiner 4 through the exhaust gas recirculation line 6 is adjusted, and the hydrogen concentration vo1% in the exhaust gas on the outlet side of the exhaust gas condenser 5 is set to a desired value (for example, 2 vol. % (Dry)), the hydrogen concentration of the exhaust gas is always maintained at 2 vol% (dry).

  If the recombination performance of the exhaust gas recombiner 4 decreases for some reason and the hydrogen concentration in the exhaust gas after passing through the exhaust gas condenser 5 increases to a concentration exceeding 4 vol% (dry), hydrogen combustion may occur. Therefore, the operation of the atomic coplant must be stopped.

  Therefore, when the hydrogen concentration of the exhaust gas detected by the hydrogen concentration detector 10 rises to a prescribed hydrogen concentration value, for example, 4 vol% (dry), an alarm is output and the operation of the nuclear power plant is stopped. ing.

  Therefore, in order to avoid an event in which the hydrogen concentration in the exhaust gas rises until the operation of the nuclear power plant is stopped, the recombination performance of the exhaust gas recombiner 4 is improved, and the hydrogen concentration in the exhaust gas is reduced to hydrogen. It must be reduced to a concentration that does not lead to combustion.

  Therefore, in the gaseous waste treatment facility 20 of the nuclear power plant of the present embodiment, in order to improve the recombination performance in the exhaust gas recombiner 4, the exhaust gas flowing through the exhaust gas recombiner 4 is based on the hydrogen concentration in the exhaust gas. An exhaust gas recirculation operation is performed so that the exhaust gas recombiner 4 is circulated many times.

  In this exhaust gas recirculation operation, a part of the exhaust gas is branched from the downstream side of the exhaust gas recombiner 4 and recirculated so as to return to the upstream side of the exhaust gas recombiner 4 through the exhaust gas recirculation line. By passing the exhaust gas through the exhaust gas recombiner 4 many times, the recombination efficiency of hydrogen and oxygen in the exhaust gas recombiner is increased, and the hydrogen concentration in the exhaust gas at the outlet of the exhaust gas condenser 5 is lowered to a desired concentration.

  In the operation method by the gas waste treatment facility of this embodiment, as shown in FIG. 1, the exhaust gas flow path 15 on the upstream side of the air extractor 4 is connected to the exhaust gas flow path 15 on the downstream side of the exhaust gas condenser 5. Since the branched exhaust gas recirculation line 6 is connected, the exhaust gas suction force by the air extractor 3 installed in the exhaust gas flow path 15 upstream of the exhaust gas recombiner 4 is circulated through the exhaust gas recirculation line 6. It can be used as a drive source for recirculating exhaust gas.

  In the gaseous waste treatment facility 20 of this embodiment, a part of the exhaust gas flowing down the exhaust gas condenser 5 is sucked from the upstream side of the air extractor 3 through the exhaust gas recirculation line 6 by the suction force of the air extractor 3. Since the driving source for flowing the exhaust gas into the exhaust gas recombiner 4 is used, the exhaust gas can be circulated through the exhaust gas recombiner 4 any number of times.

  As a result, in the gaseous waste treatment facility 20 of the present embodiment, the hydrogen concentration vol% in the exhaust gas on the outlet side of the exhaust gas condenser 5 is set to a desired value (for example, 2 vol% (dry)) that can prevent hydrogen combustion. It becomes possible to control.

  Therefore, if the gaseous waste treatment facility of the wood embodiment is used, the recombination efficiency of the exhaust gas recombiner 4 can be increased without providing a dedicated blower for supplying exhaust gas to the exhaust gas recirculation line 6. It becomes possible to reduce the hydrogen concentration in the exhaust gas at the outlet of the condenser 5 to a desired concentration.

  According to the present embodiment, the exhaust gas recombination is performed by adjusting the flow rate of the recirculation line so that the hydrogen concentration in the exhaust gas becomes a desired value without installing a dedicated blower for supplying the exhaust gas to the exhaust gas recirculation line. It is possible to realize a gas waste treatment facility and an operation method of the gas waste treatment facility that can improve the recombination performance of the vessel.

  The present invention is applicable to a gas waste treatment facility for removing or treating gas waste in a boiling water nuclear power plant and a method for operating the gas waste treatment facility.

  1: nuclear reactor, 2: condenser, 3: air extractor, 4: exhaust gas recombiner, 5: exhaust gas condenser, 6: exhaust gas recirculation line, 7: exhaust gas recirculation line flow control valve, 8: Exhaust tube, 9: noble gas hold-up device, 10: hydrogen concentration detector, 15: exhaust gas system, 20: gas waste treatment facility, 30: control device.

Claims (2)

An air extractor for extracting gaseous waste by using water vapor as a driving source in an exhaust gas flow path for flowing down water vapor and gaseous waste supplied from a condenser for condensing water vapor generated in a nuclear reactor, and an air extractor Exhaust gas recombiner that processes the gaseous waste extracted in step 1, exhaust gas condenser that condenses water vapor in the exhaust gas flowing down from the exhaust gas recombiner, and radioactive noble gas in the exhaust gas that flows down the exhaust gas condenser In a gas waste treatment facility equipped with a rare gas hold-up device for treating the waste gas and an exhaust cylinder for discharging the exhaust gas flowing down the rare gas hold-up device out of the system,
An exhaust gas recirculation line arranged to branch from the outlet side of the exhaust gas condenser and return a part of the exhaust gas passed through the exhaust gas condenser to the exhaust gas flow path between the condenser and the air extractor; A flow rate control valve that is installed in the exhaust gas recirculation line and adjusts the flow rate of the exhaust gas flowing through the exhaust gas recirculation line, and a hydrogen concentration detector that detects the hydrogen concentration of the exhaust gas flowing through the exhaust gas flow path downstream of the exhaust gas condenser And a control device for adjusting the flow rate control valve based on the hydrogen concentration of the exhaust gas detected by the hydrogen concentration detector, and the exhaust gas is recombined through the exhaust gas recirculation line using the air extractor as a drive source. Gas waste treatment facility characterized by circulating in a container. Water vapor generated in the nuclear reactor is condensed in a condenser, and gaseous waste flowing down from the condenser through an exhaust gas flow path is extracted by an air extractor using steam as a drive source, and extracted by the air extractor. Gaseous waste is treated by an exhaust gas recombiner, water vapor in the exhaust gas flowing down from the exhaust gas recombiner is condensed by an exhaust gas condenser, and radioactive noble gas in the exhaust gas flowing down the exhaust gas condenser is diluted. In the operation method of the gas waste treatment facility that treats by the gas holdup device and exhausts the exhaust gas flowing down the rare gas holdup device out of the system by the exhaust pipe,
The exhaust gas condenser was flowed down through an exhaust gas recirculation line that was branched from the outlet side of the exhaust gas condenser and connected to an exhaust gas flow path between the condenser and the air extractor. A part of the exhaust gas is returned to the upstream side of the air extractor, and the flow rate of the exhaust gas flowing through the exhaust gas recirculation line is adjusted based on the hydrogen concentration of the exhaust gas that has passed through the exhaust gas condenser. A method for operating a gas waste treatment facility, wherein the exhaust gas is circulated to the exhaust gas recombiner through the exhaust gas recirculation line as a driving source.

Images