CN115901115A - Secondary side gas mixing regulation and control method for helium leakage detection equipment of heat transfer pipe of nuclear evaporator - Google Patents
Secondary side gas mixing regulation and control method for helium leakage detection equipment of heat transfer pipe of nuclear evaporator Download PDFInfo
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- CN115901115A CN115901115A CN202211451492.7A CN202211451492A CN115901115A CN 115901115 A CN115901115 A CN 115901115A CN 202211451492 A CN202211451492 A CN 202211451492A CN 115901115 A CN115901115 A CN 115901115A
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a secondary side gas mixing regulation and control method of a helium leakage detection device for a heat transfer pipe of a nuclear evaporator, which comprises the following steps: connecting a gas circulation system with an industrial control system, drying and isolating the secondary side at the lower part of an evaporator, starting pressurizing to Abar, starting a circulating pump for gas stirring, calculating the helium percentage to be set in helium/air mixed gas according to the secondary pressure of the evaporator, and calculating the helium percentage to be injected: b × B% - (Pt 1 × Ct 1))/(B-Pt 1); opening compressed air and helium; obtaining each parameter; after helium is filled, the helium is continuously mixed after the concentration is uniform and the pressure is stable; and continuously injecting mixed gas of air and helium into the secondary side until the pressure is filled to Bbar +/-C percent, and the helium concentration at the top and the bottom is b% +/-C percent. The helium leakage detection device can realize accurate matching of helium and air, and has higher inflation speed than the conventional helium leakage detection device at present.
Description
Technical Field
The invention belongs to the field of nuclear power detection equipment, and particularly relates to a secondary side gas mixing regulation and control method of helium leakage detection equipment for a heat transfer pipe of a nuclear evaporator.
Background
The heat transfer pipe of the nuclear power station evaporator is used as a pressure boundary of a primary loop and a secondary loop and has double functions of heat exchange and a secondary safety barrier. The method has the characteristics of dense tube bundles and thin tube walls, and once the thin-wall tubes and welding lines are damaged under normal operation and accident conditions, the leakage of radioactive fission products can be caused, and the radioactive fission products must be periodically overhauled to ensure the safe operation of the nuclear power station. The helium leak detection is an effective means for checking the sealing performance of the heat transfer pipe of the evaporator, and is also a mandatory in-service check project of RSME specifications. According to the standard RSEM pressurized water reactor nuclear power plant in-service inspection rule, the steam generator heat transfer pipe is subjected to a 100% helium mass spectrum leak detection experiment after a circuit hydrostatic test is carried out for ten years of overhaul. During detection, after the secondary side of the steam generator is dried, emptied and isolated, a mixed gas of tracer gas helium is filled, so that pressure difference is generated on two sides of the tube wall of a heat transfer tube of the steam generator. When leakage points exist on the wall of the heat transfer pipe, helium can enter the heat transfer pipe through the defect opening, and gas in the heat transfer pipe is sucked out of the outlet of the primary side heat transfer pipe by using a suction gun probe and then sent into a mass spectrometer for analysis so as to determine whether leakage exists, size and position. The detection process can be divided into 6 key steps of secondary side drying, secondary side emptying isolation, mixed gas of helium and air on the secondary side, primary side emptying drying, equipment installation on one side, inspection starting and the like. Filling a trace gas helium/air mixed gas is a crucial link, and if the concentration of the filled helium is higher, the helium is decompressed in a relatively closed space of the nuclear island, so that the background of the helium concentration in the air is increased, and the accuracy and the detection sensitivity of a detection result are influenced; if the helium is filled to the bottom, the process requirement of the inspection cannot be met. The secondary side of the steam generator is internally provided with a secondary separator, a steam-water separation dryer and other complex internal structures, the size is large, if the concentration of helium cannot be effectively controlled, a detection experiment cannot be carried out, and an accurate leakage rate is obtained, so that the test failure is caused. The detection time of one evaporator is generally more than 24 hours, and helium gas is lighter than air and moves upwards after standing and gathers at the top of a container, so that the concentration of the helium gas is different at different positions of the whole length of the heat transfer pipe, and the measurement result has errors. The secondary side has a large volume, and the long helium filling time affects the whole key path of overhaul, which is not allowed. In addition, the helium filling time is too long, and the suffocation risk exists. Aiming at a helium leakage detection technology and equipment for a steam generator heat transfer pipe of a pressurized water reactor nuclear power station, the conventional secondary side gas mixing regulation and control method for helium leakage detection of the heat transfer pipe of the evaporator cannot accurately and uniformly mix gas on the secondary side of the evaporator.
Disclosure of Invention
The invention aims to provide a secondary side gas mixing regulation and control method of helium leakage detection equipment for a heat transfer pipe of a nuclear evaporator, which can be used for rapidly and accurately allocating mixed gas.
In order to solve the technical problem, the invention adopts the following technical scheme: a secondary side gas mixing regulation and control method of helium leakage detection equipment for a heat transfer pipe of a nuclear evaporator is disclosed, wherein the leakage detection equipment comprises:
the gas circulating system is connected with the evaporator and comprises an air source, a helium source, an air distributor, a gas mixing injection cabinet, a gas distributor, a first flange cover plate and a measuring joint which are arranged on an eyelet of the evaporator, a second flange cover plate and a measuring joint which are arranged on a manhole of the evaporator, a circulating pump, a lower helium concentration sensor and an upper helium concentration sensor;
which is used for controlling a gas circulation system and comprises an industrial personal computer and a control system,
the regulation and control method comprises the following steps:
the method comprises the following steps: connecting a gas circulating system with an industrial control system and well installing the gas circulating system and an evaporator, enabling dry air to enter a gas mixing injection cabinet through an air distributor and to be mixed with helium in the injection cabinet, enabling the mixed gas to pass through the gas distributor and to be interconnected with a plurality of holes in a steam generator, connecting a gas outlet at a manhole of the evaporator to a gas inlet of a circulating pump, and connecting an outlet of the circulating pump to the gas distributor to form gas flowing circulation;
step two: and drying and isolating the secondary side at the lower part of the evaporator, closing all manholes and eyelets, and starting pressurizing to Abar.
Step three: when the pressure is increased to Abar and the Abar is checked to be qualified, starting a gas stirring circulating pump to enable gas at the upper part and the lower part of the secondary side to circularly flow;
step four: calculating the percentage of helium to be set in the helium/air mixture according to the secondary pressure of the evaporator, wherein the set helium concentration is calculated by the following formula:
reading the pressure and concentration reached at the point t1, and marking Pt1 and Ct1;
calculating the helium partial pressure Pt1 multiplied by Ct1;
desired helium partial pressure at end of pressurization: b × B% bar;
calculating the required helium partial pressure: b × B% bar- (Pt 1 × Ct 1);
calculating the total pressure to be added: B-Pt1;
calculating the percentage of helium injected: b × B% - (Pt 1 × Ct 1))/(B-Pt 1)
Setting a calculation proportion; opening compressed air and helium on the injection cabinet, enabling the air channel to immediately generate gas flow, and enabling the helium channel to respond to a set value according to a set proportion under the control action of an industrial control system;
step five: acquiring a compressed air flow value, helium concentration at the lower part of an eyelet at the secondary side of the evaporator, a helium concentration top helium concentration value at an eyelet at the upper part of the evaporator and a pressure value at the secondary side of a mixed gas outlet;
step six: after helium is filled for a period of time, stopping filling helium for several minutes, and under the stirring of a circulating pump, continuously recovering mixing after the upper helium gas and the lower helium gas have uniform concentration and stable pressure, wherein a staged helium filling method is adopted;
step seven: continuously filling helium to the secondary side, and injecting air and helium mixed gas until the pressure of the helium/air mixed gas is filled to Bbar.a +/-C%, and the helium concentration at the top and the bottom is b% +/-C%; and when the helium concentration and the pressure reach the requirements, starting a helium leak detection test.
Optimized, A is more than or equal to 1 and less than or equal to 4; b is more than or equal to 5 and less than or equal to 7, B is more than or equal to 10 and less than or equal to 20, and C is more than or equal to 8 and less than or equal to 15.
Optimally, A is more than or equal to B/3 and less than or equal to 2B/3.
Optimized, a =3, b =6, b =16, c =10.
The invention has the beneficial effects that: the invention can automatically mix air and helium according to a set proportion and inject the mixture into the secondary side of the steam generator; the accurate ratio of helium to air can be realized, and the gas filling speed is higher than that of the conventional helium leak detection equipment at present; the gas filled into the secondary side can be stirred, so that helium is uniformly distributed, and water vapor condensation is prevented; the secondary side sealing is ensured, meanwhile, the helium concentration and pressure can be measured in real time, and the detection environment is ensured to be effective.
Drawings
FIG. 1 is a schematic view of a system connection device of the present invention;
FIG. 2 is a flow chart of an embodiment of a gas mixing method.
Detailed Description
The invention is described in detail below with reference to embodiments shown in the drawings:
as shown in fig. 1, the leak detection apparatus includes: the gas circulating system is connected with the evaporator and comprises an air source 1, a helium source 2, an air distributor 3, a gas mixing injection cabinet 4, a gas distributor 5, a first flange cover plate and a measuring joint 6 which are arranged on an eyelet of the evaporator, a second flange cover plate and a measuring joint 7 which are arranged on a manhole of the evaporator, a circulating pump 8, a lower helium concentration sensor 10 and an upper helium concentration sensor 9; the industrial control system is used for controlling the gas circulation system and comprises an industrial control computer 12 and a control system 11.
The air distributor 3 is used for distributing air provided by an air source, the gas mixing injection cabinet 4 is used for outputting mixed gas formed after the air provided by the air distributor is mixed with helium provided by a helium source, the gas distributor 5 is used for distributing the mixed gas output by the injection cabinet, the first flange cover plate and the measuring joint 6 are used for sealing three eyelets on the secondary side of the steam generator, the second flange cover plate and the measuring joint 7 are installed on a manhole, and the circulating pump 8 is connected between the gas distributor and the circulating gas joint and used for stirring gas in the secondary side. The gas mixing injection cabinet 4 is used for realizing secondary drying and secondary side helium/air mixing pressurization. And a secondary side helium-air mixed gas outlet is connected to the secondary side eye hole, so that the secondary side is dried and filled with helium. During the inspection, under the control of a control system, air/helium is uniformly mixed according to a proportion and then is filled into the secondary side of the evaporator by adjusting the flow of helium and dry air, and the concentration of helium on the secondary side is ensured to reach a specified value.
An upper helium concentration sensor 9 for acquiring the concentration of helium in the upper space of the secondary side of the evaporator is connected with the second flange cover plate and the measuring joint 7 and is arranged at a manhole of the secondary side of the evaporator; a lower helium concentration sensor 10 for acquiring a helium concentration value of a lower space at the secondary side of the evaporator is connected with the first flange cover plate and the measuring joint 6 and is arranged at an eye hole at the secondary side of the evaporator; the pressure sensor is arranged at the mixed gas outlet connecting pipe and is used for acquiring the secondary side pressure of the evaporator; the control system 11 and the industrial personal computer 12 collect and control the pressure, helium concentration, and gas flow rate.
As shown in fig. 2, the secondary side gas mixing control method of the helium leak detection device for the heat transfer pipe of the nuclear evaporator comprises the following steps:
the method comprises the following steps: connecting a gas circulating system with an industrial control system and well installing the gas circulating system and an evaporator, enabling dry air to enter a gas mixing injection cabinet through an air distributor and to be mixed with helium in the injection cabinet, enabling the mixed gas to pass through the gas distributor and to be interconnected with a plurality of holes in a steam generator, connecting a gas outlet at a manhole of the evaporator to a gas inlet of a circulating pump, and connecting an outlet of the circulating pump to the gas distributor to form gas flowing circulation;
step two: and drying and isolating the secondary side at the lower part of the evaporator, closing all manholes and eyelets, and starting pressurizing to 3bar.
Step three: when the pressure is increased to 3bar and the pressure is checked to be qualified, starting a gas stirring circulating pump to enable gas at the upper part and the lower part of the secondary side to circularly flow;
step four: calculating the percentage of helium to be set in the helium/air mixture according to the secondary pressure of the evaporator, wherein the set helium concentration is calculated by the following formula:
reading the pressure and concentration reached at the point t1, and marking Pt1 and Ct1;
calculating the helium partial pressure Pt1 multiplied by Ct1;
desired helium partial pressure at the end of pressurization: 6 × 16% bar =0.96bar;
calculating the partial pressure of helium to be added to be 0.96bar- (Pt 1 x Ct 1);
calculating the total pressure to be added: 6-Pt1;
calculating the percentage of helium injected: 0.96- (Pt 1 × Ct 1))/(6-Pt 1)
Setting a calculation proportion; opening compressed air and helium on the injection cabinet, enabling the air channel to immediately generate gas flow, and enabling the helium channel to respond to a set value according to a set proportion under the control action of an industrial control system;
step five: acquiring a compressed air flow value, a helium concentration at the lower part of an eyelet 6 at the secondary side of the evaporator, a helium concentration top helium concentration value at a manhole 7 at the upper part of the evaporator and a pressure value at the secondary side of a mixed gas outlet;
step six: after helium is filled for a period of time, stopping filling helium for several minutes, and under the stirring of a circulating pump, continuously recovering mixing after the upper helium gas and the lower helium gas have uniform concentration and stable pressure, wherein a staged helium filling method is adopted;
step seven: continuously filling helium to the secondary side, and injecting air and helium mixed gas until the pressure of the helium/air mixed gas is filled to 6bar +/-10%, and the helium concentration at the top and the bottom is 16% +/-10%; and when the helium concentration and the pressure reach the requirements, starting a helium leak detection test.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention.
Claims (4)
1. A secondary side gas mixing regulation and control method of nuclear evaporator heat transfer pipe helium leak detection equipment is disclosed, wherein the leak detection equipment comprises:
the gas circulating system is connected with the evaporator and comprises an air source, a helium source, an air distributor, a gas mixing injection cabinet, a gas distributor, a first flange cover plate and a measuring joint which are arranged on an eyelet of the evaporator, a second flange cover plate and a measuring joint which are arranged on a manhole of the evaporator, a circulating pump, a lower helium concentration sensor and an upper helium concentration sensor;
an industrial control system for controlling the gas circulation system, which comprises an industrial control computer and a control system,
the method is characterized in that:
the regulation and control method comprises the following steps:
the method comprises the following steps: connecting a gas circulating system with an industrial control system and well installing the gas circulating system and an evaporator, enabling dry air to enter a gas mixing injection cabinet through an air distributor and to be mixed with helium inside the injection cabinet, enabling the mixed gas to pass through the gas distributor and to be interconnected with a plurality of holes in a steam generator, connecting a gas outlet at the manhole of the evaporator to a gas inlet of a circulating pump, and connecting an outlet of the circulating pump to the gas distributor to form gas flowing circulation;
step two: and drying and isolating the secondary side at the lower part of the evaporator, closing all manholes and eyelets, and starting pressurizing to Abar.
Step three: when the pressure is increased to Abar and the Abar is checked to be qualified, starting a gas stirring circulating pump to enable gas at the upper part and the lower part of the secondary side to circularly flow;
step four: calculating the percentage of helium to be set in the helium/air mixture according to the secondary pressure of the evaporator, wherein the set helium concentration is calculated by the following formula:
reading the pressure and concentration reached at the point t1, and marking Pt1 and Ct1;
calculating the helium partial pressure Pt1 multiplied by Ct1;
desired helium partial pressure at the end of pressurization: b × B% bar;
calculating the required helium partial pressure: b × B% bar- (Pt 1 × Ct 1);
calculate the total pressure to add: B-Pt1;
calculating the percentage of helium injected: b × B% - (Pt 1 × Ct 1))/(B-Pt 1)
Setting a calculation proportion; opening compressed air and helium on the injection cabinet, wherein gas flow appears in the air channel immediately, and the helium channel responds to a set value according to a set proportion under the control action of an industrial control system;
step five: acquiring a compressed air flow value, a helium concentration at the lower part of an eye hole on the secondary side of the evaporator, a helium concentration value at the top of the helium concentration at a human hole on the upper part of the evaporator and a pressure value of the secondary side of a mixed gas outlet;
step six: after helium is filled for a period of time, stopping filling helium for a few minutes, and continuously recovering mixing after the upper helium gas and the lower helium gas have uniform concentration and stable pressure under the stirring of a circulating pump, wherein a staged helium filling method is adopted;
step seven: continuously filling helium to the secondary side, and injecting air and helium mixed gas until the pressure of the helium/air mixed gas is filled to Bbar.a +/-C%, and the helium concentration at the top and the bottom is b% +/-C%; and when the helium concentration and the pressure reach the requirements, starting a helium leak test.
2. The secondary side gas mixing regulation and control method of the nuclear evaporator heat transfer pipe helium leak detection device according to claim 1, characterized by comprising the following steps: a is more than or equal to 1 and less than or equal to 4; b is more than or equal to 5 and less than or equal to 7, B is more than or equal to 10 and less than or equal to 20, and C is more than or equal to 8 and less than or equal to 15.
3. The secondary side gas mixing regulation and control method of the nuclear evaporator heat transfer pipe helium leak detection device according to claim 2, characterized by comprising the following steps: b/3 is more than or equal to A and less than or equal to 2B/3.
4. The secondary side gas mixing regulation and control method of the nuclear evaporator heat transfer pipe helium leak detection device according to claim 2, characterized by comprising the following steps: a =3,b =6,b =16,c =10.
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| CN202211451492.7A CN115901115A (en) | 2022-11-21 | 2022-11-21 | Secondary side gas mixing regulation and control method for helium leakage detection equipment of heat transfer pipe of nuclear evaporator |
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| CN202211451492.7A CN115901115A (en) | 2022-11-21 | 2022-11-21 | Secondary side gas mixing regulation and control method for helium leakage detection equipment of heat transfer pipe of nuclear evaporator |
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