CN110828004A - An overpressure protection device for high temperature gas-cooled reactor test and its use method - Google Patents

Abstract

An overpressure protection device for a high temperature gas-cooled reactor test and a method of using the same, comprising installing a test tool with a special interface on the top of a reactor pressure vessel, and the test tool is respectively connected with a safety valve and a pressure transmitter. An electric isolation valve is installed upstream of the connection with the test fixture, and the measurement signal of the pressure transmitter is transmitted to the controller. The output end of the controller is respectively connected to the pressure source, the intake isolation valve and the electric isolation valve. The pressure source passes through the intake air. The isolation valve is connected to the reactor pressure vessel. The invention ensures the safety of the large metal pressure vessel during the air pressure test and prevents equipment damage caused by accidental overpressure.

Description

An overpressure protection device for high temperature gas-cooled reactor test and its use method

technical field

The invention relates to the technical field of high-pressure pressure test protection for metal pressure vessels, in particular to an overpressure protection device for high-temperature gas-cooled reactor tests and a method for using the same.

Background technique

The primary circuit pressure vessel of a nuclear power plant, as the second safety barrier, is an important device to prevent the release of radioactive effluents to the outside world. It is bulky and complicated in processing technology. The strength test of the primary loop pressure vessel of the reactor is required. The strength test is divided into hydraulic test and air pressure test. Considering the high risk of the air pressure test, the pressure vessel of the pressurized water reactor and the general pressure vessel are all tested by the hydraulic pressure test.

Different from the pressurized water reactor nuclear power plant, the high temperature gas-cooled nuclear power plant uses inert gas such as helium or carbon dioxide as the coolant, graphite as the moderator, and the core structure is a graphite matrix. Moisture is allowed. According to the limitation of ASME BPVC-III-I-NB sub-volume NB-6000, only the air pressure test can be used instead of the water pressure test. The strength test of the high temperature gas-cooled reactor, especially the pebble bed type high temperature gas-cooled reactor pressure vessel, can only use the air pressure test.

The air pressure test conditions of high temperature gas-cooled reactors at home and abroad are different, and the settings for overpressure protection are also different. By comparing the air pressure test technology of the German THTR reactor and the Tsinghua HTR-10 experimental reactor, the German THTR adopts the structural form of prestressed concrete and the air pressure test pressure is 4.4MPa, and no overpressure protection device is used during the air pressure test. The HTR-10 experimental reactor adopts a metal pressure vessel, and the air pressure test pressure is 3.85MPa, and no overpressure protection device is adopted during the air pressure test. The HTR-PM demonstration project uses a metal pressure vessel, and the air pressure test is 9MPa. Because the compressibility of gas is much greater than that of water, and considering that the boosting process of the air pressure test is much slower than that of the water pressure test, the HTR-PM does not design an overpressure protection device during the air pressure test stage.

However, the difference between HTR-PM and THTR and HTR-10 is that HTR-PM uses compressed air as the air pressure test medium. According to the highest test pressure, a total of nearly 50 tons of compressed air is required. The medium capacity is extremely high, and the test risk is greatly increased. There are few precedents for air pressure tests at home and abroad. During the air pressure test, the temperature change has a great influence on the pressure change. Due to the risk of overpressure due to the change of the test temperature, in order to ensure that the pressure vessel is not damaged during the test process, the HTR-PM needs to consider an overpressure protection device during the air pressure test stage.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide an overpressure protection device for high temperature gas-cooled reactor testing and a method of using the same to ensure the safety of large metal pressure vessels during the gas pressure test and prevent accidental overpressure equipment damage.

In order to achieve the above object, the technical scheme adopted in the present invention is:

An overpressure protection device for a high temperature gas-cooled reactor test, comprising a test tool 2 with a special interface installed on the top of a reactor pressure vessel 1, and the test tool 2 is respectively connected with a safety valve 4 and a pressure transmitter 5, the said An electric isolation valve 3 is installed upstream of the connection between the safety valve 4 and the test fixture 2, and the measurement signal of the pressure transmitter 5 is transmitted to the controller 6. The output ends of the controller 6 are respectively connected to the pressure source 7 and the intake isolation valve 8. As well as the electric isolation valve 3 , the pressure source 7 is connected to the reactor pressure vessel 1 through the intake isolation valve 8 .

The test tool 2 is provided with an exhaust through hole and an instrument interface, the exhaust through hole is connected with the safety valve 4 , and the instrument interface is connected with a pressure transmitter 5 .

The test tool 2 is connected to the manhole or other flange interface of the pressure vessel 1 through a flange.

The test tool 2 is connected with the isolation valve 3 and the pressure transmitter 5 by welding.

The isolation valve 3 and the safety valve 4 are connected by flanges.

The dedicated interface is the butt joint process interface between the safety valve 4 and the vessel flange blind plate of the reactor pressure vessel 1. The two ends of the short pipe are welded to the butt test tool 2, and the flange blind plate side adopts welding methods such as socket welding or surfacing welding. Install the safety valve exhaust connection pipe, weld the safety valve end seat flange in the 4th section of the safety valve, and realize the sealing connection with the safety valve flange through the welding connection pipe of the end seat flange.

The controller 6 is a control system, usually in the form of an industrial computer or a centralized control system (DCS). Control instructions to deal with special situations.

A method of using an overpressure protection device for a high temperature gas-cooled reactor test:

When the reactor is carrying out the air pressure test, connect the test tool 2 to the manhole or other flange interface of the pressure vessel 1, that is, to complete the connection between the device and the pressure vessel, and set the interlocking closing value of the isolation valve 3 and the opening in the controller 6. Conditions, set the pressure source 7 and the intake isolation valve 8 to interlock and close the fixed value, the system pressure is transmitted to the controller 6 through the pressure transmitter 5, and the real-time system pressure in the controller 6 is compared with the set protection pressure. , when the system pressure exceeds the protection setting of the compressor 7 and the intake isolation valve 8, the controller 6 sends a signal to instruct the interlock to cut off the power supply of the pressure source 7, and the interlock closes the intake isolation valve 8, so that the system and the pressure source Isolation, if the system pressure still rises after isolating the pressure source, after reaching the preset protection value of the safety valve 4, the safety valve 4 is opened to discharge part of the system medium to protect the pressure vessel and the system from the risk of overpressure damage.

Beneficial effects of the present invention:

In the overpressure protection stage, the present invention cuts off the main path leading to the system boosting through logic control, eliminates the system overpressure caused by external factors before the safety valve takes off, reduces the accidental event of the safety valve taking off, and prevents the container from releasing pressure due to the safety valve taking off. cause internal pressure fluctuations.

During the pressure maintenance and leak detection stage, the possibility of external leakage caused by internal leakage of the safety valve set by overpressure protection can be effectively reduced by controlling the electric isolation valve in front of the safety valve to close.

The overpressure protection device has a simple structure, is easy to operate in engineering, and has a low cost. It can effectively prevent the overpressure of the container, and can ensure that no additional leakage points are added during the air tightness test. It is the best solution for overpressure protection of large metal pressure vessels, especially the primary circuit pressure vessels of high temperature gas-cooled reactors.

By directly installing the overpressure protection device on the reactor pressure vessel, the existing interface of the pressure vessel can be effectively used, and the pressure loss along the pipeline caused by the connection between the safety valve and the system can be effectively reduced, and the safety valve can realize the overpressure more quickly and accurately. pressure protection function.

In the present invention, the safety valve is directly installed on the top of the pressure vessel to prevent the pressure vessel from being overpressured; in the air pressure test, the pressure relief speed is relatively slow, and the safety valve is directly connected with the nozzle on the upper part of the pressure vessel, which effectively reduces the pressure loss along the pipeline. To meet the requirements of protecting vessels and systems in the overpressure protection stage.

Considering the influence of the safety valve sealing on the leakage rate of the system, the present invention adopts the method of isolating the safety valve in stages. A condition that results in an increase in the overall leak rate of the system.

Description of drawings

Figure 1 is a schematic structural diagram of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1: The system air pressure test provides compressed gas into the pressure vessel 1 through the pressure source 7 and the inlet isolation valve 8 and other equipment.

According to the requirements of ASME BPVC-III-I-NB sub-volume NB-7000 "the pressure loss along the pipeline generated by the connection between the system and the safety valve 4 should not be greater than 3% of the release pressure", so the safety valve 4 is directly installed in on the pressure vessel body. In order to install the pressure transmitter 5 and the safety valve 4 without changing the design structure of the original pressure vessel, the connection tool 2 is installed in the manhole of the pressure vessel 1 or other flange interfaces in the form of flanges.

The connection tool 2 is provided with a connection through hole of the safety valve 4 and a connection through hole of the pressure transmitter 5 .

An electric isolation valve 3 is set in front of the safety valve 4, and the connection tool 2 is connected with the isolation valve 3 and the pressure transmitter 5 by welding.

The isolation valve 3 and the safety valve 4 are installed in the form of flange connection, which is convenient for the regular verification of the safety valve 4.

The pressure transmitter 5 transmits the signal to the controller 6, and automatically controls the isolation valve 3, the pressure source 7 and the intake isolation valve 8 through the temporary control logic.

A test tool 2 with a special interface is installed on the reactor pressure vessel 1. The tool 2 is provided with an exhaust through hole for connecting the safety valve 4 and an instrument interface for connecting the pressure transmitter 5. An electric isolation valve is installed upstream of the safety valve 4. 3. The measurement signal of the pressure transmitter 5 is transmitted to the controller 6 (DCS can be used in the power station, and the combination configuration of the industrial computer and the data collector can be used for other types), and the controller 6 adds temporary control logic to control the pressure source 7, Intake isolation valve 8 and temporary electric isolation valve 3.

The present invention adds an electric isolation valve 3 before the safety valve on the basis of the traditional safety valve 4, and controls the electric isolation valve 3 to close in the air tightness test stage through logic, so as to prevent the leakage of the safety valve from affecting the overall leakage rate of the system, In the strength test stage, the electric isolation valve 3 is kept in a normally open state, and the safety valve 4 is connected with the equipment 1 to realize the overpressure protection function. In the initial stage of overpressure, the intake isolation valve 8 is automatically cut off by the logic control compiled by the controller 6, the pressure source 7 is interlocked and shut down, and the overpressure caused by the introduction of internal and external sources in the pressure range from the initial stage of overpressure to the jump of the safety valve 4 is blocked. , in order to prevent the adverse effect of releasing part of the test medium on the system pressure after the safety valve 4 jumps off. If the pressure still rises after the system is isolated, release the test medium through the safety valve 4 to protect the system equipment.

The difference between the set value of the logic protection pressure set by the interlocking stop and closing the intake isolation valve 8 and the cut-off pressure source 7 and the take-off set value of the safety valve should fully consider the influence of temperature changes on the system pressure fluctuation to prevent the safety valve 4 from The system pressure changes and jumps. Taking HTR-PM as an example, the maximum test pressure of the pressure test is 9.0MPa, the recommended protection signal of the interlocking cut-off intake valve 8 and the shut-off pressure source 7 is 9.2MPa, and the take-off pressure of the safety valve 4 is recommended to be set to 9.7MPa ( The factory hydraulic test pressure of the pressure vessel is 10MPa).

The working principle of the present invention is as follows:

First, connect the overpressure protection device as shown in the figure, set the interlocking closing value and opening conditions of the isolation valve 3 in the controller 6, set the interlocking closing value of the pressure source 7 and the intake isolation valve 8, and the system pressure passes through the pressure The transmitter 5 is sent to the controller 6, and the real-time system pressure is compared with the set protection pressure in the controller 6. When the system pressure exceeds the protection set value of the compressor 7 and the intake isolation valve 8, the controller 6. Send a signal to instruct the interlock to cut off the power supply of the pressure source 7, and the interlock to close the intake isolation valve 8 to isolate the system from the pressure source. If the system pressure still rises after the pressure source is isolated, the preset protection value of the safety valve 4 is reached. Afterwards, the safety valve 4 is opened to discharge part of the system medium to protect the pressure vessel and the system from the risk of overpressure damage.

In order to meet the requirements of the air tightness test, adding a safety valve 4 in the system is equivalent to adding a known leak point. Therefore, in the air tightness test stage, in order to avoid the influence of the leakage of the safety valve 4 on the overall leakage rate of the system, it is necessary to interlock and close the safety valve. Electric isolation valve 3 in front of valve 4.

At the same time, the invention can realize the requirement of overpressure protection of the air pressure test strength test, and can also meet the sealing requirement of the air tightness test system.

Claims (8)

1. The overpressure protection device for the high-temperature gas cooled reactor test is characterized by comprising a test tool (2) with a special interface, which is mounted at the top of a reactor pressure vessel (1), wherein the test tool (2) is respectively connected with a safety valve (4) and a pressure transmitter (5), an electric isolation valve (3) is mounted at the upstream of the joint of the safety valve (4) and the test tool (2), a measurement signal of the pressure transmitter (5) is transmitted to a controller (6), the output end of the controller (6) is respectively connected with a pressure source (7), an air inlet isolation valve (8) and the electric isolation valve (3), and the pressure source (7) is connected with the reactor pressure vessel (1) through the air inlet isolation valve (8).

2. The overpressure protection device for the high-temperature gas cooled reactor test according to claim 1, wherein the test fixture (2) is provided with an exhaust through hole and an instrument interface, the exhaust through hole is connected with the safety valve (4), and the instrument interface is connected with the pressure transmitter (5).

3. The overpressure protection device for the high-temperature gas cooled reactor test according to claim 1, wherein the test tool (2) is connected with a manhole or other flange interfaces of the pressure vessel (1) through a flange.

4. The overpressure protection device for the high-temperature gas cooled reactor test according to claim 1, wherein the test fixture (2) is connected with the isolation valve (3) and the pressure transmitter (5) in a welding mode.

5. The overpressure protection device for the high temperature gas cooled reactor test according to claim 1, wherein the isolation valve (3) and the safety valve (4) are connected by a flange.

6. The overpressure protection device for the high-temperature gas-cooled reactor test according to claim 1, wherein the special interface is a butt joint process interface of the safety valve (4) and a vessel flange blind plate of the reactor pressure vessel (1), the two ends of the butt joint test tool (2) are welded through a short pipe, a safety valve exhaust connecting pipe is installed on the flange blind plate side in a socket welding or surfacing welding mode, a safety valve end seat flange is welded on one section of the safety valve (4), and the connecting pipe welded through the end seat flange is connected with the safety valve flange in a sealing mode.

7. The overpressure protection device for the high-temperature gas cooled reactor test according to claim 1, wherein the controller (6) is a control system, such as an industrial personal computer or a centralized control system, and is used for acquiring data signals, issuing control commands through compiled internal control logic, realizing an automatic closed-loop feedback control function, and manually inputting control commands to deal with special situations.

8. The use method of the overpressure protection device for the high-temperature gas cooled reactor test is characterized in that the overpressure protection device comprises a pressure sensor, a pressure sensor and a pressure sensor;

when a reactor carries out an air pressure test, a test tool (2) is connected with a manhole or other flange interfaces of a pressure container (1), namely, the butt joint of a device and the pressure container is completed, an interlocking closing fixed value and an opening condition of an isolation valve (3) are set in a controller (6), an interlocking closing fixed value of a pressure source (7) and an air inlet isolation valve (8) is set, system pressure is transmitted to the controller (6) through a pressure transmitter (5), the real-time pressure of the system is compared with a set protection pressure in the controller (6), when the system pressure exceeds the protection fixed values of a compressor (7) and the air inlet isolation valve (8), the controller (6) sends a signal instruction to interlock and cut off a power supply of the pressure source (7), the air inlet isolation valve (8) is interlocked and closed, the system is isolated from the pressure source, if the system pressure is still raised after the pressure source is isolated, and the protection fixed value preset by a safety valve (4) is reached, the safety valve (4) is opened to discharge part of the system medium, and the pressure container and the system are protected from the risk of overpressure damage.

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