JP2013204854A - Apparatus and method for filling gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove residual moisture in a heat transfer tube when filling gas in a primary side of a heat exchanger.SOLUTION: An apparatus for filling gas fills gas in a primary side of a steam generator (heat exchanger) 101 that includes: the primary side in communication with the inside of a heat transfer tube 105; and a secondary side that is outside of the heat transfer tube 105, and includes: a vacuuming means 2 for vacuuming the primary side; a gas supplying means 3 for supplying gas in the primary side; and a heating means 4 for heating the heat transfer tube 105.

Description

  The present invention relates to a gas sealing device and a gas sealing method for sealing a gas inside a heat transfer tube when manufacturing a heat exchanger such as a steam generator.

  In a pressurized water reactor (PWR), light water is used as a reactor coolant and neutron moderator, and high-temperature high-pressure water that does not boil throughout the core is sent to a steam generator for heat exchange. The steam is generated by this, and the steam is sent to a turbine generator to generate power. In this pressurized water reactor, heat of the high-temperature and high-pressure primary cooling water is transmitted to the secondary cooling water by the steam generator, and steam is generated by the secondary cooling water. In this steam generator, primary cooling water flows inside a large number of thin heat transfer tubes, heat is transferred to secondary cooling water flowing outside, and steam is generated, and a turbine is rotated by the steam to generate electric power.

  In this steam generator, a tube group outer cylinder is disposed at a predetermined distance from the inner wall surface in a hollow hermetically sealed body portion, and a plurality of inverted U-shaped heat transfer tubes are arranged in the tube group outer cylinder. The end of each heat transfer tube is supported by the tube plate, and the inlet side water chamber and the outlet side water chamber of the primary cooling water are partitioned by a bowl-shaped water chamber mirror and partition plate joined to the lower part of the tube plate Has been. The water chamber mirror is provided with an inlet side nozzle that opens to the outside in the inlet side water chamber, and an outlet side nozzle that opens to the outside in the outlet side water chamber. The inlet side nozzle is connected to a cooling water pipe for supplying high-temperature and high-pressure primary cooling water from the pressurized water reactor, and the outlet side nozzle is a cooling water for returning the primary cooling water after the heat exchange to the pressurized water reactor. Piping is connected. Further, the water chamber mirror is provided with maintenance manholes in the inlet side water chamber and the outlet side water chamber, respectively. In addition, an inlet portion of secondary cooling water is provided in the body portion above the outer tube of the tube group, and a steam-water separator and a moisture separator are arranged side by side, above which steam is placed. There is an exit.

  Patent Document 1 describes a process of inserting a heat transfer tube when manufacturing a steam generator.

JP 2009-168405 A

  As described above, the heat transfer tube, the water chamber side inlet side water chamber and the outlet side water chamber, the tube plate water chamber side surface, and the partition plate are used as the primary side of the steam generator as a primary high-temperature cooling water. It is important to prevent rust and maintain its integrity until the steam generator is manufactured and transported to a nuclear facility, and nitrogen or inert gas is enclosed. .

  In order to efficiently replace the air with the gas, the primary side is once evacuated to remove the air, and then the gas is sealed. Here, if moisture is present inside the heat transfer tube including water vapor in the air, the air is adiabatically expanded by evacuation at a normal evacuation speed, and the moisture solidifies and becomes ice as the temperature decreases. Since the vaporization rate of ice is slow, ice remains even after evacuation, and this melts after gas filling and becomes residual moisture. This residual moisture makes it difficult to maintain the integrity of the primary side.

  The present invention solves the above-described problems, and provides a gas sealing device and a gas sealing method capable of removing residual moisture inside a heat transfer tube when gas is sealed on the primary side of a heat exchanger. For the purpose.

  In order to achieve the above-described object, the gas sealing apparatus of the present invention is configured to supply gas to the primary side of a heat exchanger that forms a primary side that communicates with the inside of the heat transfer tube and a secondary side that is outside the heat transfer tube. A gas sealing device for sealing, comprising: a vacuuming means for evacuating the primary side; a gas supply means for supplying gas to the primary side; and a heating means for heating the heat transfer tube. To do.

  According to this gas sealing apparatus, the heat transfer tube is heated by the heating means at the time of evacuation and gas supply, so that adiabatic expansion is less likely to occur at the time of evacuation in the heat transfer tube, or adiabatic expansion occurs and the temperature is increased. The water is effectively removed by melting the ice that has been reduced and solidified, and evaporating the water that has become liquid. As a result, the humidity on the primary side can be sufficiently reduced, that is, the vapor pressure can be sufficiently reduced, so that the dew point temperature at which the primary side does not condense can be maintained even with a long-term temperature change from shipment to delivery. .

  Moreover, the gas sealing apparatus of the present invention is characterized by comprising oxygen concentration measuring means for measuring the oxygen concentration on the primary side and dew point temperature measuring means for measuring the dew point temperature on the primary side.

  In order to achieve the above-described object, the gas sealing method of the present invention includes a heat exchanger that configures a primary side that communicates with the inside of a heat transfer tube and a secondary side that is the outside of the heat transfer tube. In which the primary side is evacuated and gas is injected into the primary side while the heat transfer tube is heated.

  According to this gas sealing method, the heat transfer tube is heated at the time of evacuation and gas supply, so that adiabatic expansion is less likely to occur at the time of evacuation in the heat transfer tube, or the adiabatic expansion occurs and the temperature is lowered and moisture is reduced. The dew point temperature at which no dew condensation can be maintained can be maintained by effectively removing the water by evaporating the water that has become solid by melting the solidified ice. As a result, residual moisture inside the heat transfer tube can be removed.

  According to the present invention, when gas is sealed on the primary side of the heat exchanger, the residual moisture inside the heat transfer tube is maintained at a dew point temperature at which the primary side does not condense even with a long-term temperature change from shipment to delivery. To a level that can be done.

FIG. 1 is a configuration diagram of a gas sealing apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart of the gas filling method according to the embodiment of the present invention. FIG. 3 is an explanatory diagram showing the configuration of the steam generator.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 3 is an explanatory diagram showing the configuration of the steam generator. As shown in FIG. 3, the steam generator 101 as a heat exchanger has a trunk portion 102. The trunk portion 102 has a hollow cylindrical shape that extends in the vertical direction and is hermetically sealed. The lower half portion has a slightly smaller diameter than the upper half portion. The body portion 102 is provided with a heat transfer tube group 105A in the lower half thereof. The heat transfer tube group 105A includes a plurality of heat transfer tubes 105 having an inverted U shape. Each heat transfer tube 105 has a U-shaped arc portion facing upward, a lower end portion is inserted and supported in the tube hole 104 a of the tube plate 104, and an intermediate portion is supported by a plurality of tube support plates 106.

  The body portion 102 has a water chamber mirror 107 joined to the lower end thereof. The water chamber mirror 107 is partitioned into an inlet side water chamber 107A and an outlet side water chamber 107B by a partition plate 108 with an opening edge formed in a bowl shape joined to the tube plate 104. One end of each heat transfer tube 105 communicates with the inlet side water chamber 107A, and the other end of each heat transfer tube 105 communicates with the outlet side water chamber 107B. The inlet-side water chamber 107A is formed with an inlet-side nozzle 107Aa that communicates with the outside of the trunk 102, and the outlet-side water chamber 107B is formed with an outlet-side nozzle 107Ba that communicates with the exterior of the trunk 102.

  FIG. 1 is a configuration diagram of a gas sealing apparatus according to the present embodiment. The steam generator 101 described above is assembled in a laid-down form at the time of manufacture. Then, as a final process before shipment, for example, a gas such as nitrogen or an inert gas is sealed on the primary side and the secondary side. In this embodiment, a gas sealing device that seals gas on the primary side will be described.

  The gas sealing apparatus includes a sealing means 1, a vacuum drawing means 2, a gas supply means 3, a heating means 4, a vacuum degree measuring means 5, an oxygen concentration measuring means 6, and a dew point temperature measuring means 7. It is configured.

  The sealing means 1 seals the primary side of the steam generator 101. When the steam generator 101 is manufactured, the nozzles 107Aa and 107Ba formed on the water chamber mirror 107 are opened on the primary side. The sealing means 1 is configured as a closing lid for closing the openings of the nozzles 107Aa and 107Ba. The water chamber mirror 107 has manholes (not shown), and when the steam generator 101 is used, the opening portions of these manholes are closed by a manhole cover (not shown). At the time of gas filling, a manhole cover is included in a part of the sealing means 1 to close the manhole.

  The evacuation means 2 evacuates the primary side of the steam generator 101. The vacuum evacuation means 2 is provided on one of the closed lids, and is connected to the connection pipe 2 a that is drawn out of the water chamber mirror 107 and communicates with the inside and outside of the water chamber mirror 107. And a vacuum suction portion 2b. The vacuum suction unit 2b is configured as a vacuum pump that evacuates the primary side via the connecting pipe 2a. The connecting pipe 2a is provided with a vacuum opening / closing valve 2c for opening and closing the connecting pipe 2a. As an opening / closing lid provided with the vacuum evacuation means 2, FIG. 1 shows a closing lid for closing the outlet side nozzle 107Ba, but it may be a closing lid for closing the inlet side nozzle 107Aa.

  The gas supply means 3 supplies gas to the primary side of the steam generator 101. The gas supply means 3 includes a gas supply pipe 3a that is in the middle of the connection pipe 2a and branches from the closing lid side of the vacuum on-off valve 2c and communicates with the inside and outside of the water chamber mirror 107 through a part of the connection pipe 2a. And a gas supply unit 3b connected to the gas supply pipe 3a. The gas supply part 3b is comprised with the tank in which gas is stored, and the pump which sends out the gas of a tank. The gas supply pipe 3a is provided with a gas on / off valve 3c for opening and closing the gas supply pipe 3a in the middle thereof. Note that the gas supply pipe 3a may be configured so as to be provided directly on one side of the closing lid and communicate with the inside and outside of the water chamber mirror 107 without passing through the connection pipe 2a.

  The heating means 4 heats the heat transfer tube 105. In the present embodiment, the heating means 4 is configured as a hot air supply unit 4 a having a heater and a fan so as to send hot air to the secondary side of the steam generator 101. When the hot air is sent to the secondary side of the steam generator 101, only two openings on the secondary side of the steam generator 101 are closed and heated to the secondary side through one opening. Air is sent in and the cooled air is discharged from the secondary side through the other opening. As shown in FIG. 1, the two openings that are opened include an opening (for example, a hand hole) on the tube plate 104 side of the heat transfer tube 105 and an opening on the U-shaped end side of the heat transfer tube 105 ( For example, a small diameter nozzle) is preferable for appropriately heating the heat transfer tube 105. The heating unit 4 may be configured to heat the heat transfer tube 105 from the outside by covering the body portion 102 of the steam generator 101 with a heater or the like.

  The degree-of-vacuum measuring means 5 measures the degree of vacuum on the primary side of the steam generator 101. The degree-of-vacuum measuring means 5 is configured as a pressure gauge that measures the internal pressure on the primary side.

  The oxygen concentration measuring means 6 measures the oxygen concentration on the primary side of the steam generator 101. The oxygen concentration measuring means 6 may be arranged in the connecting pipe 2a separately from the vacuum degree measuring means 5.

  The dew point temperature measuring means 7 measures the dew point temperature on the primary side of the steam generator 101. The dew point temperature measuring means 7 may be arranged in the connecting pipe 2a separately from the vacuum degree measuring means 5.

  FIG. 2 is a flowchart of the gas filling method according to the embodiment of the present invention. First, heating of the heat transfer tube 105 is started by the heating means 4 (step S1). The heating of the heat transfer tube 105 is preferably started at least before evacuation. Next, the primary side is evacuated (step S2). That is, the gas on-off valve 3c is closed and the vacuum on-off valve 2c is opened to operate the vacuum suction unit 2b. Then, evacuation is continued until the primary side reaches a predetermined pressure (degree of vacuum) (step S3: No), and when the predetermined pressure is reached (step S3: Yes), the evacuation is stopped and gas is injected (step S4). . Then, steps S2 to S4 are performed until the primary side has a predetermined oxygen concentration and a predetermined temperature (step S5: No), and when the primary side has a predetermined oxygen concentration and a predetermined temperature (step S5: Yes), the primary side Gas is injected until the side is pressurized to a predetermined pressure (step S6: No and step S7), and when the predetermined pressure is reached (step S6: Yes), heating of the heat transfer tube 105 by the heating means 4 is stopped (step S6). S8) The primary side is sealed, that is, the vacuum on-off valve 2c and the gas on-off valve 3c are closed, and this operation is completed.

  As described above, the gas sealing apparatus according to the present embodiment is configured so that the steam generator (heat exchanger) 101 constituting the primary side communicating with the heat transfer tube 105 and the secondary side outside the heat transfer tube 105 is the primary side. A gas sealing device for sealing a gas with a vacuum suction means 2 for evacuating the primary side, a gas supply means 3 for supplying the gas to the primary side, and a heating means 4 for heating the heat transfer tube 105. .

  According to this gas sealing device, the heat transfer tube 105 is heated by the heating means 4 during evacuation and gas supply, so that adiabatic expansion is less likely to occur during evacuation in the heat transfer tube 105 or adiabatic expansion occurs. The water is effectively removed by evaporating the water that has become liquid by melting the ice that has been solidified as the temperature drops. For this reason, since the humidity on the primary side can be sufficiently reduced, that is, the vapor pressure can be sufficiently reduced, it is possible to maintain a dew point temperature at which the primary side does not condense even with a long-term temperature change from shipment to delivery. . As a result, it becomes possible to remove residual moisture inside the heat transfer tube 105.

  In addition, the gas sealing apparatus of the present embodiment includes an oxygen concentration measuring unit 6 that measures the primary oxygen concentration and a dew point temperature measuring unit 7 that measures the primary dew point temperature.

  In addition, the gas sealing method of the present embodiment is such that the steam generator (heat exchanger) 101 constituting the primary side communicating with the inside of the heat transfer tube 105 and the secondary side outside the heat transfer tube 105 is arranged on the primary side. A gas filling method for filling a gas, wherein the heat transfer tube 105 is heated when the gas is injected after the primary side is evacuated.

  According to this gas sealing method, the heat transfer tube 105 is heated during evacuation and gas supply, thereby making it difficult for adiabatic expansion to occur during evacuation in the heat transfer tube 105, or adiabatic expansion occurs and the temperature decreases. The dew point temperature which does not condense can be maintained by effectively removing the moisture by evaporating the water that has become solid and melted by melting the ice solidified. As a result, it becomes possible to remove residual moisture inside the heat transfer tube 105.

  The gas sealing method of the present embodiment includes a step of evacuating the primary side and a step of injecting a gas when the primary side reaches a predetermined degree of vacuum. Vacuuming and gas injection are performed until the concentration reaches a predetermined temperature, while the heat transfer tube 105 is continuously heated. According to this gas sealing method, the primary atmosphere can be set to an oxygen concentration and a dew point temperature at which no residual moisture is generated inside the heat transfer tube.

DESCRIPTION OF SYMBOLS 1 Sealing means 2 Vacuum drawing means 3 Gas supply means 4 Heating means 5 Vacuum degree measuring means 6 Oxygen concentration measuring means 7 Dew point temperature measuring means 101 Steam generator 105 Heat transfer tube

Claims (4)

About a heat exchanger that constitutes a primary side leading to the inside of a heat transfer tube and a secondary side outside the heat transfer tube, a gas sealing device that seals gas on the primary side,
Evacuation means for evacuating the primary side;
Gas supply means for supplying gas to the primary side;
Heating means for heating the heat transfer tube;
A gas sealing device comprising: Oxygen concentration measuring means for measuring the oxygen concentration on the primary side;
Dew point temperature measuring means for measuring the dew point temperature on the primary side;
The gas sealing device according to claim 1, comprising: About a heat exchanger that constitutes a primary side that leads to the inside of a heat transfer tube and a secondary side that is the outside of the heat transfer tube, a gas sealing method for sealing gas to the primary side,
A gas filling method, wherein the primary side is evacuated and a gas is injected into the primary side while the heat transfer tube is heated. Evacuating the primary side;
Next, a step of injecting gas when the primary side has a predetermined degree of vacuum;
The evacuation and gas injection are performed until the primary side has a predetermined oxygen concentration and reaches a predetermined temperature, and the heat transfer tube is continuously heated during that time. Gas filling method.

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