JP2006292531A - Method for surface treatment of heat transfer tube of steam generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for surface treatment a of a heat transfer tube of a steam generator capable of executing a treatment for inhibiting elution of Ni from a heat transfer tube of a steam generator by using an inexpensive apparatus of a very simple constitution at reduced costs and man-hours for treatment work. <P>SOLUTION: The method for surface treatment of a heat transfer tube of a steam generator made of a Ni-Cr-Fe system alloy comprises the steps of assembling a heat transfer tube in the interior of a steam generator and circulating a surface treatment liquid in the heat transfer tube via a heat-temperature fluid outlet chamber and a high-temperature liquid inlet chamber to form a surface coating on the inner surface of the heat transfer tube. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface treatment method for a heat transfer tube for a steam generator, which is applied to a heat transfer tube for a steam generator of a nuclear power generation facility and is made of a Ni—Cr—Fe alloy.

The steam generator of the nuclear power generation facility has about 3000 heat exchange tubes for heat exchange bent in a U shape and assembled in the steam generator body, and the inside of the heat transfer tubes is filled with high-temperature water (heating fluid) from the reactor. The steam is exchanged to exchange heat with the feed water, and steam for driving the steam turbine is generated from the feed water.
Such a heat transfer tube is usually made of a high Ni (high Ni content) Ni-Cr-Fe alloy, but in high temperature water circulating between the reactors, it comes into contact with the high temperature water. In some cases, Ni which is a main component in the alloy is dissolved from the inner surface of the heat transfer tube.

As one of the surface treatment methods for the inner surface of a heat transfer tube for a steam generator for preventing the dissolution of Ni as described above, the technique of Patent Document 1 (Japanese Patent Laid-Open No. 5-195191) is provided.
In such a technique, after immersion treatment in a nitric acid solution at 40 ° C. or higher at a concentration of 10 to 40% with Cr ⁶⁺ ions added at 0.5 g / liter or more,
In a vacuum of 10 ⁻² to 10 ⁻⁴ torr, elution of Ni or the like into the heat transfer tube is suppressed by performing heat treatment for a predetermined time in a predetermined temperature range.
JP-A-5-195191

As described above, in the technique provided in Patent Document 1 (Japanese Patent Laid-Open No. 5-195191), in a heat transfer tube for a steam generator made of a high Ni Ni—Cr—Fe alloy, In order to suppress the dissolution of Ni from the inner surface of the heat transfer tube in the high-temperature water circulating through the heat transfer tube, after being immersed in the heat transfer tube nitric acid solution for 0.1 hour or more, heat treatment is performed in a predetermined temperature range for a predetermined time in a vacuum. Has been given.
However, in the prior art, the Ni elution prevention treatment of the heat transfer tube is configured to be performed by combining immersion treatment in a nitric acid bath and heat treatment in a heat treatment furnace. Since the heat treatment was performed separately, the device was complicated and large, and the device cost was increased. In order to combine the two-step treatment of the immersion treatment in the nitric acid bath and the heat treatment in the heat treatment furnace, There was a problem that a large amount of man-hours was required for the Ni elution prevention treatment, and the processing work cost also increased.

  The present invention has been made in view of such a situation, and the object thereof is to reduce the Ni elution prevention treatment from the heat transfer tube for the steam generator with a very simple configuration and low cost apparatus. An object of the present invention is to provide a method for treating the surface of a heat transfer tube for a steam generator, which can be carried out with reduced man-hours and reduced processing costs.

In order to solve the problems of the prior art, the present invention relates to a Ni—Cr—Fe based alloy (usually 30 to 80% Ni, 10 to 40% Cr, and the balance is Fe. Is a composition of 70% Ni, 15% Cr of the 600 alloy and the balance of Fe, or a composition of 60% Ni, 30% Cr of the 690 alloy and the remainder of Fe, etc.). A surface treatment method for a heat tube, wherein the heat transfer tube is assembled in a steam generator body, and the surface treatment liquid is passed through the heat transfer tube through a high-temperature fluid inlet / outlet chamber of the steam generator, thereby the heat transfer tube. A surface coating is formed on the inner surface.
As the surface treatment liquid, a nitric hydrofluoric acid aqueous solution, a nitric acid aqueous solution, a citric acid aqueous solution, or the like is preferably used, and the surface treatment liquid is circulated in the heat transfer tube by a pump.
Here, the “heat transfer tube” in the present invention includes both a heat transfer thin tube and a heat transfer tube bundle in which a plurality of the heat transfer thin tubes are bundled as shown in the following embodiments.

In addition to the above invention, the following configuration is preferable.
(1) Heated air heated to a predetermined temperature is supplied into the steam generator body to heat the heat transfer tube, and a surface treatment liquid is caused to flow through the heat transfer tube.
(2) Pure water heated to a predetermined temperature is supplied into the steam generator body to heat the heat transfer tube, and a surface treatment liquid is passed through the heat transfer tube.

  Further, the present invention is a surface treatment method for a heat generator tube for a steam generator made of a Ni—Cr—Fe-based alloy, wherein the heat transfer tube is removed from the steam generator body, and the surface treatment liquid is in a state of the heat transfer tube alone. Is passed through the heat transfer tube to form a surface coating on the inner surface of the heat transfer tube.

In addition to the above invention, the following configuration is preferable.
(1) the heat transfer tube in a single state, the heat transfer tube was warmed with a heater maintained at a predetermined temperature to flow through a surface treatment liquid to the heat transfer tube. In this case, the heater is preferably wound around a plurality of heat transfer tubes.
(2) With the heat transfer tube as a single unit, the heat transfer tube is housed in a constant temperature layer and maintained at a predetermined temperature, and a surface treatment liquid is passed through the heat transfer tube. In this case, it is preferable to use water heated to a predetermined temperature as the constant temperature layer and immerse the heat transfer tube in the constant temperature water.

  The present invention is also a surface treatment method for a heat transfer tube for a steam generator made of a Ni-Cr-Fe alloy, wherein the heat transfer tube formed in a U-shape is in a single state, and the inlet of the surface treatment liquid is provided. And a surface coating is formed on the inner surface of the heat transfer tube by injecting a surface treatment liquid from the inlet of the heat transfer tube and immersing the inner surface of the heat transfer tube in the surface treatment solution for a predetermined time. is doing.

In addition to the above invention, the following configuration is preferable.
That is, the heat transfer tube is immersed in a hot water tank in which warm water heated inside is stored, the heat transfer tube is maintained at a predetermined temperature, and the inner surface of the heat transfer tube is immersed in a surface treatment liquid for a predetermined time.
Further, the present invention provides an inlet duct connected to one of the openings of the heat transfer tube bundle made up of a plurality of heat transfer thin tubes removed from the steam generator, and an outlet duct connected to the other, and the surface treatment is simultaneously performed on the heat transfer tube bundle. The method of applying is also included.

  According to the present invention, with the heat transfer tube assembled in the steam generator body, the surface treatment liquid prepared to a predetermined concentration is transferred using the pump provided in the pipe for circulating the surface treatment liquid. By flowing through the tube and forming a surface coating on the inner surface of the heat transfer tube, it is possible to suppress elution of Ni from the inner surface of the heat transfer tube into the heating fluid in the heat transfer tube during actual operation.

Therefore, according to the present invention, a heat treatment tube comprising a plurality of heat transfer thin tubes is prepared by a single operation using a pump with a surface treatment liquid prepared at a predetermined concentration while the heat transfer tube is assembled in the steam generator body. The elution prevention treatment of Ni from the inner surface of the heat transfer tube can be performed with a very simple operation and a small number of work steps of flowing through the tube, and the work cost can be reduced. That is, it becomes possible to simultaneously perform processing of a heat transfer tube composed of a plurality of heat transfer thin tubes.
In addition, with the heat transfer tube assembled in the steam generator body, the high temperature fluid inlet / outlet nozzle of the steam generator body is used as it is, and the surface treatment liquid circulation pipe and circulation pump are installed, Can be made to flow through the heat transfer tube, so that no special immersion bath is required as in the prior art, and the apparatus is simpler and smaller than the prior art, and the apparatus cost can be greatly reduced.

  Further, in addition to the invention, in the steam generator main body, heated air heated to a predetermined temperature is supplied through a nozzle of the steam generator main body to heat the heat transfer tube, The surface treatment liquid is allowed to flow through, or pure water heated to a predetermined temperature is supplied into the steam generator body through a nozzle of the steam generator body to heat the heat transfer tube. If the surface treatment liquid is made to flow through the heat transfer tube, the heat transfer tube is heated from the outer surface side and maintained at a high temperature by the heated air or pure water heated to a predetermined temperature. Since the surface treatment liquid can be passed through the heat transfer tube and the steam generator itself is used, a separate heat treatment furnace is not required. In addition, the time for forming the surface coating on the inner surface of the heat transfer tube can be shortened and the number of man-hours for surface treatment can be reduced as compared with normal temperature.

  Further, according to the present invention, the heat transfer tube is removed from the steam generator body, and the surface treatment liquid is passed through the heat transfer tube in a state of the heat transfer tube alone to form a surface coating on the inner surface of the heat transfer tube. Therefore, in a state of a heat transfer tube alone, the surface treatment liquid prepared to a predetermined concentration is made to flow through the heat transfer tube with a single operation using a pump, with a very simple operation and less work man-hours. Ni elution prevention treatment from the inner surface can be performed, and the operation cost can be reduced. In addition, since the present invention performs the surface treatment with a single heat transfer tube, the place where the surface treatment is performed can be freely selected.

  Further, in addition to the invention, in the state of the heat transfer tube alone, the heat transfer tube is heated with a heater and maintained at a predetermined temperature, and a surface treatment liquid is allowed to flow through the heat transfer tube. With the heater, the heat transfer tube is heated from the outer surface side and kept at a high temperature, so that the surface treatment liquid can be passed through the heat transfer tube, and the surface coating on the inner surface of the heat transfer tube can be made more than at normal temperature. The formation time can be shortened, and the number of man-hours for surface treatment can be reduced.

  Further, in addition to the invention, the heat transfer tube alone is housed in a constant temperature layer maintained at a predetermined temperature to hold the heat transfer tube at a predetermined temperature, and the surface treatment liquid is passed through the heat transfer tube. If configured so that the entire heat transfer tube is housed in a constant temperature layer controlled at a target constant temperature and is uniformly heated from the outer surface side of the heat transfer tube and kept at a high temperature, the heat transfer tube It is possible to allow the surface treatment liquid to flow through the heat transfer tube while keeping the temperature at the target high temperature at all times, and the time required for surface coating can be reduced to a minimum, further reducing the man-hours for surface treatment. Can be realized.

  Further, according to the present invention, the heat transfer tube is erected with the surface treatment liquid inlet and outlet facing upward, the surface treatment liquid is injected from the inlet of the heat transfer tube, and the inner surface of the heat transfer tube is used as the surface treatment liquid. Since the surface coating is formed on the inner surface of the heat transfer tube by dipping for a predetermined time, the surface coating can be formed on the inner surface of the heat transfer tube by simply pouring the surface treatment liquid into the standing heat transfer tube and holding it for a certain period of time. Pumps and piping are not required.

  Further, in addition to the above invention, the heat transfer tube is immersed in a hot water tank in which warm water heated inside is stored, the heat transfer tube is maintained at a predetermined temperature, and a surface treatment liquid is placed in the heat transfer tube. If configured to flow, the entire heat transfer tube is housed in a hot water tank held at a high temperature, and the surface treatment liquid is kept in the heat transfer tube in a state where the temperature of the heat transfer tube is always kept high. Can be poured for a certain period of time, and the time required for forming the surface coating can be shortened by means simpler than those of the inventions described above.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
Here, in the following embodiments, the “heat transfer tube” includes both a heat transfer thin tube and a heat transfer tube bundle in which a plurality of the heat transfer thin tubes are bundled.
FIG. 1 is a cross-sectional view of an essential part showing a surface treatment method for a heat transfer tube for a steam generator according to a first embodiment of the present invention.
In FIG. 1, 100 is a steam generator, 1 is a shell constituting the steam generator body of the steam generator 100, 120 is a tube plate fixed to the lower inner periphery of the shell 1, and 2 is a tube plate 120 having a lower end portion. It is a supported heat transfer tube. These heat transfer tubes 2 are made of a Ni-Cr-Fe alloy of high Ni, and are formed into U-shaped bent tubes whose lower ends are opened, and the lower ends of the heat transfer tubes 2 are brazed to the tube plate 120, etc. It is fixed by.
Reference numeral 4 denotes a high-temperature fluid inlet chamber into which high-temperature fluid (high-temperature water) is introduced. Reference numeral 5 denotes a high-temperature fluid outlet chamber. The high-temperature fluid inlet chamber 4 and the high-temperature fluid outlet chamber 5 are partitioned by a partition plate 04. Reference numeral 10 denotes a high-temperature fluid inlet nozzle for introducing a high-temperature fluid into the high-temperature fluid inlet chamber 4, and 11 denotes a high-temperature fluid outlet nozzle for deriving high-temperature fluid from the high-temperature fluid outlet chamber 5.

  3 is a tube support plate for supporting a plurality of locations in the intermediate portion of the heat transfer tube 2, and 9 is a wrapper cylinder fixed to the inner periphery of the shell 1, and the outer periphery of each tube support plate 3 is formed by the wrapper cylinder 9. It is supported. 01 is a downcomer of the shell 1, 6 is a steam chamber formed in the upper part inside the shell 1, 7 is a water supply inlet nozzle for introducing water to the downcommer 01, and 8 is a steam outlet in the steam chamber 6. This is a steam outlet nozzle.

During the operation of the steam generator 100 configured as described above, a high-temperature fluid (high-temperature water) generated in a nuclear reactor (not shown) is introduced from the high-temperature fluid inlet nozzle 10 into the high-temperature fluid inlet chamber 4, and the high-temperature fluid inlet chamber. While entering the heat transfer pipe 2 opened to 4 and flowing through the heat transfer pipe 2, heat is exchanged with the feed water introduced from the feed water inlet nozzle 7 to the downcomer 01, and the feed water is heated to generate steam. .
The high-temperature fluid lowered in temperature by such heat exchange flows out from the heat transfer tube 2 into the high-temperature fluid outlet chamber 5 and returns to the nuclear reactor through the high-temperature fluid outlet nozzle 11. On the other hand, the steam generated from the feed water by heat exchange with the high-temperature fluid is stored in the steam chamber 6 and then sent to the steam turbine (not shown) through the steam outlet nozzle 8 to perform expansion work and generate power. .

The present invention relates to a surface treatment method for the heat transfer tube 2 for a steam generator configured as described above.
In the first embodiment of the present invention, the heat transfer tube 2 is still assembled in the shell (steam generator body) 1, that is, in the assembled state of the steam generator 100, the high-temperature fluid inlet nozzle 10 of the steam generator 100 and The high temperature fluid outlet nozzle 11 is used to connect the inlet flange 13a of the processing liquid pipe 13 in which the processing liquid pump 12 is interposed to the high temperature fluid inlet nozzle 10, and the outlet flange 13b of the processing liquid pipe 13 is connected to the high temperature fluid outlet nozzle. The surface treatment liquid is made to flow through the heat transfer tube 2 by the treatment liquid pump 12.

As the surface treatment liquid, nitric hydrofluoric acid aqueous solution, nitric acid aqueous solution, citric acid aqueous solution and the like are used, preferably prepared with 0.1 to 5% by weight hydrofluoric acid aqueous solution and 3 to 30% by weight nitric acid aqueous solution. A nitric hydrofluoric acid aqueous solution, a 5 to 50% by weight nitric acid aqueous solution, and a 5 to 20% by weight citric acid aqueous solution (or an ammonium citrate aqueous solution, hereinafter the same) are used. The surface treatment liquid prepared to have a predetermined concentration enters the heat transfer tubes 2 from the treatment solution pipe 13 through the high temperature fluid inlet chamber 4 and flows through the heat transfer tubes 2 by the treatment liquid pump 12. A surface coating is formed on the inner surface of the heat transfer tube 2. That is, the surface treatment liquid forms a surface coating on the inner surface of the heat transfer tube 2, while the treatment liquid pump 12 → the treatment liquid pipe 13 → the high temperature fluid inlet chamber 4 → the heat transfer pipe 2 → the high temperature fluid outlet chamber 5 → the treatment liquid pipe 13. → Circulates the path of the processing liquid pump 12. In the first embodiment of the present invention, first, the inner surface of the heat transfer tube 2 is treated with a nitric hydrofluoric acid aqueous solution to dissolve a scale which is an undesired corroded oxide film, and then treated with a nitric acid aqueous solution. Thus, an oxidized surface film in which Cr is concentrated is formed. By forming a surface film in which Cr is concentrated, the outflow of Ni (nickel) is suppressed. As the nitric hydrofluoric acid treatment step, a nitric hydrofluoric acid aqueous solution prepared with 0.1 to 5% by weight HF and 3 to 30% by weight HNO ₃ is preferably used at room temperature to 100 ° C. for 30 to 120 minutes. Can be mentioned. Further, as the nitric acid treatment step, with 5 to 50% HNO ₃ aqueous solution, it includes treatment conditions 30 to 120 minutes at room temperature to 100 ° C.. Alternatively, first, the surface film may be formed by using a nitric acid aqueous solution after first flowing through a citric acid aqueous solution and removing the scale.

  As described above, according to the first embodiment, the surface treatment liquid prepared to a predetermined concentration with the heat transfer tube 2 assembled in the shell (steam generator body) 1 is used as a tube for circulating the surface treatment liquid. The heat transfer tube 2 is made to flow through the heat transfer tube 2 using a treatment liquid pump 12 provided in the treatment liquid tube 13, and a surface coating is formed on the inner surface of the heat transfer tube 2 by surface treatment, so that the heat transfer tube 2 during actual operation is formed. The elution of Ni from the inner surface into the heating fluid in the heat transfer tube can be suppressed. Since the present invention is a method of assembling the heat transfer tube to the steam generator main body and subjecting the surface of the heat transfer tube to a surface treatment, it is of course applicable to cleaning of a new heat transfer tube. It is also possible to stop the operation and perform the surface treatment in the heat transfer tube according to the first embodiment.

Therefore, according to the first embodiment, a plurality of surface treatment liquids prepared to a predetermined concentration with the heat transfer tube 2 being assembled in the steam generator main body by a single operation using the treatment liquid pump 12. The elution prevention treatment of Ni from the inner surface of the heat transfer tube 2 can be performed with a very simple operation and with a small number of work steps of flowing through the heat transfer tube 2 formed of a heat transfer thin tube, and the work cost can be reduced.
Further, as described above, with the heat transfer tube 2 assembled in the shell (steam generator body) 1, the nozzles of the high-temperature fluid inlets 10 and 11 of the shell (steam generator body) 1 are used as they are, and the surface treatment is performed. Since the surface treatment liquid can be passed through the heat transfer pipe 2 simply by installing the treatment liquid pipe 13 for the circulation of the liquid and the treatment liquid pump 12 for the circulation of the treatment liquid, A heat treatment furnace is not required, and the apparatus is simpler and smaller than the prior art.

FIG. 2 is a cross-sectional view of an essential part corresponding to FIG. 1 showing a second embodiment of the present invention.
In the second embodiment, in addition to the first embodiment, a heating water heated to a predetermined temperature from the air supply device 15 using the feed water inlet nozzle 7 in the upper part of the shell (steam generator body) 1 is used. The inlet flange 14a of the air pipe 14 through which the warm air flows is connected to the feed water inlet nozzle 7, and the heated air heated to a predetermined temperature is supplied from the air supply device 15 into the downcomer 01 to add the heat transfer pipe 2. (The temperature of the heated air is preferably surface-treated in a temperature range from higher than room temperature to 100 ° C.), and the surface treatment liquid is put into the heat transfer tube 2 as in the first embodiment. It is configured to allow flow.
The same members as those in the first actual embodiment are denoted by the same reference numerals, and the description thereof is omitted.

According to the second embodiment, the heat treatment tube 2 is heated from the outer surface side by the heated air heated to a predetermined temperature, and the surface treatment liquid is allowed to flow through the heat transfer tube 2 while being kept at a high temperature. As a result, the time for forming the surface coating on the inner surface of the heat transfer tube 2 can be shortened and the number of man-hours for the surface treatment can be reduced as compared with the normal temperature as in the first embodiment.
Other configurations and procedures are the same as those in the first embodiment (FIG. 1).

FIG. 3 is a cross-sectional view of an essential part corresponding to FIG. 1 showing a third embodiment of the present invention.
In the third embodiment, in addition to the first embodiment, a predetermined temperature is supplied from a pure water tank 19 to a pure water pump 18 by using a flange of the water supply inlet 7 at the upper part of the shell (steam generator body) 1. An inlet flange 17a of a pure water pipe 17 for supplying pure water heated to is connected to the water supply inlet nozzle 7, and pure water heated to a predetermined temperature is supplied into the water chamber 01 by a pure water pump 18. Then, the heat transfer tube 2 is heated, and the surface treatment liquid is allowed to flow through the heat transfer tube 2 as in the first embodiment. It is preferable to perform the surface treatment in a temperature range from a temperature higher than room temperature to 100 ° C. or less by heating the heated water.
The same members as those in the first actual embodiment are denoted by the same reference numerals, and description thereof is omitted.

According to the third embodiment, the heat treatment tube 2 is heated from the outer surface side by pure water heated to a predetermined temperature, and the surface treatment liquid is allowed to flow through the heat transfer tube 2 while being kept at a high temperature. As a result, the time required for forming the surface coating on the inner surface of the heat transfer tube 2 can be shortened and the number of man-hours for the surface treatment can be reduced as compared with the normal temperature as in the first embodiment.
Other configurations and procedures are the same as those in the first embodiment (FIG. 1).

FIG. 4 is a side view of an essential part showing a surface treatment method for a single heat transfer tube according to a fourth embodiment of the present invention.
In the fourth embodiment, as shown in FIG. 4, before the heat transfer tube 2 is assembled in the shell 1 of the steam generator 100 or in a state of the heat transfer tube 2 alone removed from the steam generator 100, the heat transfer tube 2. An inlet duct 23 is connected to the inlet side, an outlet duct 24 is connected to the outlet side of the heat transfer tube 2, and a processing liquid pipe 13 having a processing liquid pump 12 interposed between the inlet duct 23 and the outlet duct 24. Connected with. As shown in FIG. 4, a fixing plate 121 may be provided in order to connect the heat transfer tube 2 stably to the ducts 23 and 24.

In the fourth embodiment, the surface treatment liquid enters the heat transfer tubes 2 from the treatment solution pipe 13 through the inlet duct 23 and flows through the heat transfer tubes 2 by the treatment liquid pump 12. A surface coating of the surface treatment liquid is formed on the inner surface of the heat transfer tube 2. That is, the surface treatment liquid forms a surface film on the inner surface of the heat transfer tube 2, and the treatment liquid pump 12 → the treatment liquid pipe 13 → the inlet duct 23 → the heat transfer pipe 2 → the outlet duct 24 → the treatment liquid pipe 13 → the treatment liquid pump 12. It is designed to circulate through the route. Note that the nitric hydrofluoric acid treatment is performed before the surface treatment method of the fourth embodiment.
In this embodiment, the same surface treatment liquid and scale as in the first embodiment can be applied, and then a surface treatment process for forming a surface film with a high chromium content can be applied.

As described above, according to the fourth embodiment, in the state of the heat transfer tube 2 alone with the heat transfer tube 2 removed from the steam generator 100, the surface treatment liquid is allowed to flow through the heat transfer tube 2 and chromium is applied to the inner surface of the heat transfer tube 2. Since a surface coating with a high content is formed, the surface treatment liquid adjusted to a predetermined concentration is caused to flow through the plurality of heat transfer tubes 2 by a single operation using the treatment solution pump 12 in the state of the heat transfer tube alone. It is possible to perform the elution prevention treatment of Ni from the inner surface of the heat transfer tube 2 with an extremely simple operation and a small number of work steps, and the work cost can be reduced.
Furthermore, according to this 4th Embodiment, the surface treatment of a desired number of heat exchanger tubes is attained.

FIG. 5 is a side view of an essential part corresponding to FIG. 4 showing a fifth embodiment of the present invention.
In the fifth embodiment, in addition to the fourth embodiment, a heater 25 is wound around the outer periphery of the heat transfer tube 2, and the heat transfer tube 2 is heated by the heater 25 and maintained at a predetermined temperature. The surface treatment liquid is made to flow through the heat transfer tube 2 in the same procedure as the embodiment. The heater 25 is connected to a power source 26 via a cable 27. The same members as those in the fourth actual embodiment are denoted by the same reference numerals, and description thereof is omitted.
According to the fifth embodiment, the surface treatment liquid can be caused to flow through the heat transfer tube 2 while the heat transfer tube 2 is heated from the outer surface side and maintained at a high temperature by the heater 25. The time for forming the surface coating on the inner surface of the heat transfer tube 2 can be shortened and the number of man-hours for the surface treatment can be reduced as compared with the normal temperature of the fourth embodiment. It is preferable to perform the surface treatment by heating the heater 25 in a temperature range from higher than room temperature to 100 ° C. or less.
Other configurations and procedures are the same as those in the fourth embodiment (FIG. 4).

FIG. 6 is a side view of an essential part showing a surface treatment method for a single heat transfer tube according to a sixth embodiment of the present invention.
In the sixth embodiment, as in the fourth embodiment, before the heat transfer tube 2 is incorporated into the shell 1 of the steam generator 100 or in a state of the heat transfer tube 2 alone removed from the steam generator 100, An inlet duct 23 is connected to the inlet side of the heat transfer tube 2, an outlet duct 24 is connected to the outlet side of the heat transfer tube 2, and a treatment liquid pump 12 is interposed between the inlet duct 23 and the outlet duct 24. The treatment liquid pipe 13 is connected.
Further, in the sixth embodiment, the surface treatment assembly of the heat transfer tube 2 similar to that in the fourth embodiment as described above is placed in a thermostatic chamber 025 in which a heating fluid (a thermostatic layer) 28 is accommodated at a predetermined temperature. The thermostat 025 is kept at a predetermined temperature, and the surface treatment liquid is passed through the heat transfer tube 2.
Reference numeral 29 denotes a temperature control device, which controls the temperature of the heated fluid (constant temperature layer) 28 to a target temperature by adjusting the amount of heating or cooling to the heated fluid 28. The same members as those in the fourth actual embodiment are denoted by the same reference numerals, and description thereof is omitted. It is preferable to perform the surface treatment in a temperature range from a temperature higher than room temperature to 100 ° C. or less by heating the heated fluid.

  According to the sixth embodiment, the assembly for surface treatment of the heat transfer tube 2 is accommodated in the heated fluid (constant temperature layer) 28 controlled to a target constant temperature, and the heat transfer tube 2 is moved from the outer surface side. Since the heat treatment tube 2 is heated and kept at a high temperature, it is possible to allow the surface treatment liquid to flow through the heat transfer tube 2 while keeping the temperature of the heat transfer tube 2 at the target high temperature at all times, thereby minimizing the formation time of the surface coating. It can be shortened to the limit, and the man-hours for surface treatment can be further reduced as compared with the fourth to fifth embodiments.

FIG. 7 is a side view of an essential part showing a surface treatment method for a single heat transfer tube according to a seventh embodiment of the present invention.
In the seventh embodiment, the heat transfer tube 2 formed in a U-shape is in a single state, the inlet and outlet of the surface treatment liquid are faced upward, and the inlet chamber of the surface treatment liquid having an inlet 31 is provided. The surface treatment liquid is injected and filled in the heat transfer tube 2 from 30 and the inner surface of the heat transfer tube 2 is immersed in the surface treatment liquid for a predetermined time so as to form a surface coating of the surface treatment liquid on the inner surface of the heat transfer tube 2. It is configured. Before the surface treatment method of the seventh embodiment, nitric hydrofluoric acid treatment or citric acid treatment for scale removal may be performed.
According to the seventh embodiment, by attaching the heat transfer tube 2 to the fixed plate 121 which is a member capable of bringing together a plurality of tubes, the heat transfer tube 2 composed of a plurality of heat transfer thin tubes is connected to an inlet for one treatment liquid. Can be surface treated at once. Further, as shown in FIG. 7, when a U-shaped heat transfer thin tube having a small diameter of the R portion is connected from the inside to a fixed plate 121 that can bundle a plurality of heat transfer thin tubes together, a small space can be used. The heat transfer tube 2 can be surface-treated at a time.

  In addition, according to the seventh embodiment, the heat transfer tube 2 is placed with the surface treatment liquid inlet and outlet facing upward, and the surface treatment liquid is injected from the inlet of the heat transfer tube 2 through the inlet 31 and the inlet chamber 30. Since the inner surface of the heat transfer tube 2 is immersed in the surface treatment liquid for a predetermined time to form a surface coating on the inner surface of the heat transfer tube 2, the surface treatment liquid is poured into the standing heat transfer tube 2 by gravity and held for a certain period of time. Thus, a surface coating can be formed on the inner surface of the heat transfer tube 2, and a processing liquid pump and a processing liquid pipe for circulating the surface processing liquid become unnecessary.

FIG. 8 is a view corresponding to FIG. 6 showing an eighth embodiment of the present invention.
In the eighth embodiment, similarly to the seventh embodiment, the heat transfer tube 2 formed in a U-shape is in a single state and is placed in a hot water tank 33 in which warm water 34 heated inside is accommodated. A fixed plate that immerses the heat transfer tube 2 so that the inlet and outlet of the surface treatment liquid face upward, and heats the heat transfer tube 2 to a predetermined temperature by hot water 34 and holds the heat transfer tube 2 together. The inner surface of the heat transfer tube 2 is injected by injecting the surface treatment solution into the heat transfer tube 2 through the inlet 31 and the inlet chamber 30 of the surface treatment solution attached to 121 and immersing the inner surface of the heat transfer tube 2 in the surface treatment solution for a predetermined time. A surface film having a high chromium content is formed. When the opening on the opposite side of the heat transfer tube 2 is fixed to a fixing plate 121 that can bundle a plurality of heat transfer thin tubes as shown in FIG. 8, surface treatment can be performed more stably. Moreover, it is preferable to perform the surface treatment in a temperature range from higher than room temperature to 100 ° C. or less by heating the heated water.
The same members as those in the seventh actual embodiment are denoted by the same reference numerals, and the description thereof is omitted.

According to the eighth embodiment, the entire heat transfer tube is housed in the hot water tank 33 held at a high temperature, and the surface of the heat transfer tube 2 is surface-treated while the temperature of the heat transfer tube 2 is always kept high. It is possible to pour the liquid and hold it for a certain period of time, and the time for forming the surface film can be shortened by simple means compared to the above embodiments.
Other configurations and procedures are the same as those in the seventh embodiment (FIG. 7).

  While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a surface treatment method for a heat transfer tube for a steam generator according to a first embodiment of the present invention. It is principal part sectional drawing corresponding to FIG. 1 which shows 2nd Embodiment of this invention. It is principal part sectional drawing corresponding to FIG. 1 which shows 3rd Embodiment of this invention. It is a principal part side view which shows the surface treatment method of the heat exchanger tube single-piece | unit which concerns on 4th Embodiment of this invention. It is a principal part side view corresponding to FIG. 4 which shows 5th Embodiment of this invention. It is a principal part side view which shows the surface treatment method of the heat exchanger tube single-piece | unit which concerns on 6th Embodiment of this invention. It is a principal part side view corresponding to FIG. 4 which shows 7th Embodiment of this invention. It is a principal part side view corresponding to FIG. 6 which shows 8th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Steam generator 01 Downcomer 2 Heat transfer tube 3 Tube support plate 04 Partition plate 4 Hot fluid inlet chamber 5 Hot fluid outlet chamber 6 Steam chamber 7 Feed water inlet nozzle 8 Feed water outlet nozzle 9 Outer cylinder 10 Hot fluid inlet nozzle 11 Hot fluid outlet Nozzle 12 Treatment liquid pump 120 Tube plate 121 Fixed plate 13 Treatment liquid pipe 14 Air tube 15 Air supply device 17 Pure water pipe 18 Pure water pump 19 Pure water tank 23 Inlet duct 24 Outlet duct 25 Heater 025 Constant temperature bath 26 Power supply 27 Cable 28 Addition Warm fluid 29 Temperature controller 30 Inlet chamber 31 Inlet 33 Hot water tank 34 Heated fluid

Claims (9)

  A surface treatment method for a steam generator heat transfer tube made of a Ni-Cr-Fe alloy, wherein the heat transfer tube is assembled in a steam generator body, and a surface treatment liquid is passed through a high-temperature fluid inlet / outlet chamber of the steam generator. A surface treatment method for a heat transfer tube for a steam generator, wherein a surface coating is formed on the inner surface of the heat transfer tube by flowing through the heat transfer tube.   The heated air is heated to a predetermined temperature in the steam generator body to heat the heat transfer tube, and a surface treatment liquid is allowed to flow through the heat transfer tube. The surface treatment method of the heat exchanger tube for steam generators as described.   The pure water heated to a predetermined temperature is supplied into the steam generator body to heat the heat transfer tube, and a surface treatment liquid is allowed to flow through the heat transfer tube. Surface treatment method for heat transfer tubes for steam generators.   A method for surface treatment of a heat transfer tube for a steam generator made of a Ni-Cr-Fe alloy, wherein the heat transfer tube is removed from the steam generator body, and the surface treatment liquid is passed through the heat transfer tube in the state of the heat transfer tube alone. A surface treatment method for a heat transfer tube for a steam generator, characterized in that a surface coating is formed on the inner surface of the heat transfer tube by flowing.   The steam generation according to claim 4, wherein the heat transfer tube is heated to a predetermined temperature by heating the heat transfer tube with a heater, and a surface treatment liquid is allowed to flow through the heat transfer tube. Surface treatment method for heat transfer tubes for equipment.   5. The steam according to claim 4, wherein the heat transfer tube is contained in a single state, the heat transfer tube is housed in a constant temperature layer and maintained at a predetermined temperature, and a surface treatment liquid is allowed to flow through the heat transfer tube. Surface treatment method for heat transfer tubes for generators.   A surface treatment method for a heat transfer tube for a steam generator made of a Ni-Cr-Fe alloy, wherein the heat transfer tube formed in a U-shape is in a single state, and the inlet and outlet of the surface treatment liquid are directed upward. And generating a surface coating on the inner surface of the heat transfer tube by injecting a surface treatment solution from the inlet of the heat transfer tube and immersing the inner surface of the heat transfer tube in the surface treatment solution. Surface treatment method for heat transfer tubes for equipment.   The heat transfer tube is immersed in a hot water tank in which warm water heated inside is stored, the heat transfer tube is held, and the inner surface of the heat transfer tube is immersed in a surface treatment liquid. The surface treatment method of the heat exchanger tube for steam generators as described.   An inlet duct is connected to one of the openings of the heat transfer tube bundle consisting of a plurality of heat transfer thin tubes removed from the steam generator, and an outlet duct is connected to the other, and the heat transfer tube bundle is subjected to surface treatment at the same time. A surface treatment method for a heat transfer tube for a steam generator according to any one of claims 4 to 6.

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