CN215713313U - Device for simultaneously pre-oxidizing inner and outer walls of boiler tube - Google Patents
Device for simultaneously pre-oxidizing inner and outer walls of boiler tube Download PDFInfo
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- CN215713313U CN215713313U CN202121986750.2U CN202121986750U CN215713313U CN 215713313 U CN215713313 U CN 215713313U CN 202121986750 U CN202121986750 U CN 202121986750U CN 215713313 U CN215713313 U CN 215713313U
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Abstract
A device for pre-oxidizing the inner wall and the outer wall of a boiler tube simultaneously comprises a reaction chamber consisting of a shell and a sealing cover, wherein a heating device is arranged on the periphery of the reaction chamber; a workpiece support for placing a boiler tube and a temperature measuring device for measuring the surface temperature of the boiler tube are arranged in an inner cavity of the reaction chamber, and a vacuumizing interface capable of being connected with vacuumizing equipment is arranged on the shell; the sealing cover is connected with the shell through a sealing gasket. By surface treatment of the boiler tubes; heating the boiler tube with the surface treated in a vacuum environment to perform pre-oxidation reaction; and cooling the boiler tube after the pre-oxidation reaction, and then introducing air to obtain the boiler tube of which the inner surface and the outer surface are selectively oxidized at the same time to generate a compact pre-oxidation film. The utility model does not damage the mechanical property of the boiler tube matrix, and has simple and efficient process and environmental protection.
Description
Technical Field
The utility model belongs to the field of boiler tubes, and relates to a device for pre-oxidizing the inner wall and the outer wall of a boiler tube simultaneously.
Background
The super/reheater is a key part of the boiler of the ultra-supercritical thermal power generating unit, the service environment of the super/reheater is very harsh, and the inner wall and the outer wall of a pipe respectively bear the oxidative corrosion action of high-temperature and high-pressure water vapor and flue gas/coal ash to form a corrosion product layer, so that great hidden danger is brought to the safe and stable operation of the boiler. First, this results in an effective wall thickness reduction of the over/reheater tube under pressure, making the tube susceptible to creep rupture. Second, the low thermal conductivity corrosion product film acts as a shield to the tube, causing over-temperature. Moreover, when the boiler is started and stopped, because the thermal expansion coefficient difference with the alloy is large, the oxide film on the inner wall of the pipe is easy to peel off, the peeled oxide film can block the pipe of the reheating/passing pipe to cause pipe explosion, and the peeled oxide film is carried out by high-flow-rate steam to erode the high-pressure and medium-pressure section turbine blades.
Therefore, in order to reduce adverse effects caused by oxidation and corrosion, it is highly desirable to improve the corrosion resistance of boiler tubes, which is also the focus of power station material development. The solutions that researchers have proposed at present include: (1) the alloy components of the boiler tube are optimized, and the contents of corrosion resistant elements such as Cr, Al, Si, RE and the like are improved; (2) the surface of the boiler pipe is modified, and the surface of the boiler pipe is formed with an aluminum-rich or chromium-rich protective coating by aluminizing or chromium plating and other methods, so that the surface of the boiler pipe is rapidly formed with continuous and complete protective Cr in the service process2O3Film or Al2O3And (3) a membrane. The fact shows that the corrosion resistance of the boiler tube can be improved by the method, but the optimization of the alloy components needs to be verified through a large number of experimental iterations so as to give consideration to the influence on the mechanical property, the processing property, the welding property and the like of the alloy, so that the cost is extremely high, and the efficiency is low; the surface modified coating has element mutual diffusion with the substrate in the service process, possibly damages the mechanical property of the substrate, and the preparation process of the coating is complex, and usually brings certain environmental pollution.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the problem of poor effect of improving the corrosion resistance of the boiler tube in the prior art, and provides a device for simultaneously pre-oxidizing the inner wall and the outer wall of the boiler tube, which can not damage the mechanical property of a boiler tube matrix on the basis of improving the corrosion resistance, and has the advantages of simple and efficient process and environmental friendliness.
In order to achieve the purpose, the utility model has the following technical scheme:
a device for pre-oxidizing the inner wall and the outer wall of a boiler tube simultaneously comprises a reaction chamber consisting of a shell and a sealing cover, wherein a heating device is arranged on the periphery of the reaction chamber; a workpiece support for placing a boiler tube and a temperature measuring device for measuring the surface temperature of the boiler tube are arranged in an inner cavity of the reaction chamber, and a vacuumizing interface capable of being connected with vacuumizing equipment is arranged on the shell; the sealing cover is connected with the shell through a sealing gasket.
Preferably, the heating device adopts an induction heating coil.
Preferably, the boiler tube is horizontally suspended and supported in the inner cavity through a plurality of workpiece supports arranged at intervals, and the induction heating coils are uniformly arranged on the periphery of the reaction chamber along the axial direction of the boiler tube.
Preferably, the temperature measuring device is a temperature measuring thermocouple arranged on the inner surface and the outer surface of the boiler tube.
Preferably, the inner wall of the inner cavity is coated with a high temperature resistant ceramic coating.
Preferably, the workpiece support is made of a high temperature resistant ceramic material.
Preferably, a cooling assembly for cooling the sealing washer is arranged inside the cover body of the sealing cover.
Preferably, the cooling assembly is a spiral coil pipe arranged along the inside of the cover body, a water inlet hole and a water outlet hole are formed in the sealing cover, and the water inlet hole and the water outlet hole are connected with a water inlet and a water outlet of the spiral coil pipe.
Compared with the prior art, the utility model has the following beneficial effects: the boiler tube is arranged in the inner cavity of the reaction chamber and heated in a low-vacuum environment, so that the inner surface and the outer surface of the boiler tube are selectively oxidized at the same time to form a compact pre-oxidation film, further, the diffusion of oxygen-containing anions and metal cations through the oxidation film is effectively blocked, and the corrosion resistance of the inner wall and the outer wall of the boiler tube is improved. The pre-oxidation reaction of the utility model is carried out in a low vacuum environment, and the utility model has no pollution and is environment-friendly. Compared with the traditional mode of improving the corrosion resistance of the boiler tube, the method can improve the corrosion resistance of the inner wall and the outer wall of the boiler tube of the power station at the same time, is simple to implement, has high efficiency, does not generate high cost, and has considerable application prospect.
Furthermore, the utility model adopts the induction heating coils which are uniformly arranged on the periphery of the reaction chamber in the axial direction to heat the boiler tube in the inner cavity of the reaction chamber, and the heat is concentrated on the inner surface and the outer surface of the boiler tube by utilizing the skin effect of alternating current, so that the microstructure of the core part of the boiler tube is not influenced. Meanwhile, the boiler tube is heated to a set temperature quickly by induction heating, and the process is simple and efficient.
Drawings
FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention;
in the drawings: 1-induction heating coil; 2-a shell; 3-a spiral coil pipe; 4-water inlet holes; 5-water outlet; 6-sealing cover; 7-inner cavity; 8-boiler tubes; 9-a workpiece holder; 10-temperature thermocouple; 11-evacuation interface.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Referring to fig. 1, the utility model provides a device for simultaneously improving the corrosion resistance of the inner wall and the outer wall of a power station boiler tube, which comprises a reaction chamber consisting of a shell 2 and a sealing cover 6, wherein a heating device is arranged on the periphery of the reaction chamber; the inner cavity 7 of the reaction chamber is internally provided with a workpiece bracket 9 for placing a boiler tube 8 and a temperature measuring device for measuring the surface temperature of the boiler tube 8. The heating device is an induction heating coil 1, and the induction heating coil 1 is powered by alternating current with the frequency of 200-300 kHz. The boiler tube 8 is horizontally suspended and supported in the inner cavity 7 through a plurality of workpiece supports 9 which are arranged at intervals, and the induction heating coils 1 are uniformly arranged on the periphery of the reaction chamber along the axial direction of the boiler tube 8 so as to ensure that the axial temperature distribution of the inner surface and the outer surface of the boiler tube 8 is uniform in the heating process. The temperature measuring device is a temperature measuring thermocouple 10 arranged on the inner surface and the outer surface of the boiler pipe 8. The shell 2 is provided with a vacuumizing interface 11, and is connected with external vacuumizing equipment through the vacuumizing interface 11. Inside spiral coil 3 that is equipped with of lid of sealed lid 6, seted up inlet opening 4 and apopore 5 on the sealed lid 6, inlet opening 4 and apopore 5 meet with spiral coil 3's water inlet and delivery port. The inner ring of the sealing cover 6 is provided with a high-temperature-resistant sealing gasket to ensure the sealing property. The inner wall of the inner cavity 7 is coated with a high-temperature resistant ceramic coating. The workpiece support 9 is made of a high-temperature-resistant ceramic material.
The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the boiler tube of the power station comprises the following steps:
performing surface treatment on the boiler pipe 8, wherein the specific mode of the surface treatment is sand blowing treatment or acid washing treatment, and removing a corrosion layer and oil stains, so that the surface quality of the boiler pipe 8 meets the requirements of GB5310-2008 seamless steel pipe for high-pressure boiler.
Placing the surface-treated boiler tube 8 on the work support 9 in the inner chamber 7, closing the sealing lid 6 to seal the inner chamber 7;
circulating cooling water is made to flow from the water inlet 4 into the spiral coil 3 inside the sealing cover 6 and out from the water outlet 5;
opening a vacuum device externally connected with the vacuum interface 11 to perform vacuum pumping so as to maintain the vacuum degree of the inner cavity 7 of the reaction chamber within a certain range; in the examples, the vacuum degree of the vacuum environment was controlled to 10-2～10-4Pa, in the range of Pa.
The ac power supply is switched on, and the induction heating coil 1 provided on the outer periphery of the reaction chamber is energized to heat the boiler tube 8 for pre-oxidation; in the embodiment, the temperature of the pre-oxidation reaction is not higher than the tempering temperature of the tube of the boiler tube 8, and the time of the pre-oxidation reaction is 10-60 min.
Closing the alternating current power supply, cooling the boiler tube 8 after the pre-oxidation reaction to room temperature, opening the vacuum-pumping port 11 to allow air to enter the reaction chamber, opening the sealing cover 6, and taking out the boiler tube 8 whose inner surface and outer surface simultaneously generate a dense pre-oxidation film.
Typically, the boiler tubes 8 are made of austenitic heat resistant steel and the dense pre-oxidized film is Cr2O3And (3) a membrane.
Example 1
(1) Selecting a Super304H boiler tube 8 with the diameter of 60mm and the wall thickness of 7mm, and carrying out acid cleaning treatment on the surface of the boiler tube to ensure that the surface quality meets the requirements of GB5310-2008 seamless steel tubes for high-pressure boilers;
(2) placing the Super304H boiler tube 8 with the surface treated on the workpiece support 9, and closing the sealing cover 6;
(3) the cooling water device is opened, so that circulating cooling water flows into the spiral coil 3 in the sealing cover 6 from the water inlet 4 and flows out from the water outlet 5, and the sealing washer is prevented from being aged due to the fact that the sealing cover 6 is heated;
(4) opening a vacuumizing device externally connected with a vacuumizing interface 11 for vacuumizing to maintain the vacuum degree in the cavity to be 10- 3Pa；
(5) Setting the frequency of an alternating current power supply to be 200kHz, switching on the alternating current power supply, and electrifying an induction heating coil 1 arranged on the periphery of the reaction chamber to heat a boiler tube 8-800 ℃ for pre-oxidation;
(6) after pre-oxidation is carried out for 20min, the power supply is turned off, the boiler pipe 8 is cooled to room temperature, the vacuumizing connector 11 is opened to enable air to enter the inner cavity 7, the sealing cover 6 is opened, and the pre-oxidized boiler pipe 8 is taken out;
(7) a layer of dense Cr is formed on the surface of the Super304H boiler tube 8 through pre-oxidation reaction2O3And (5) pre-oxidizing the film.
The above-mentioned embodiments are only preferred embodiments of the present invention, and it should be understood by those skilled in the art that the present invention can be easily modified and replaced without departing from the spirit and principle of the present invention, and the modifications and replacements are also covered by the protection scope of the claims.
Claims (8)
1. The utility model provides a device of boiler pipe inside and outside wall is preoxidized simultaneously which characterized in that: comprises a reaction chamber consisting of a shell (2) and a sealing cover (6), wherein a heating device is arranged on the periphery of the reaction chamber; a workpiece support (9) for placing a boiler tube (8) and a temperature measuring device for measuring the surface temperature of the boiler tube (8) are arranged in an inner cavity (7) of the reaction chamber, and a vacuumizing interface (11) capable of being connected with vacuumizing equipment is arranged on the shell (2); the sealing cover (6) is connected with the shell (2) through a sealing gasket.
2. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 1, wherein:
the heating device adopts an induction heating coil (1).
3. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 2, wherein:
the boiler tube (8) is horizontally suspended and supported in the inner cavity (7) through a plurality of workpiece supports (9) which are arranged at intervals, and the induction heating coils (1) are uniformly arranged on the periphery of the reaction chamber along the axial direction of the boiler tube (8).
4. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 1, wherein:
the temperature measuring device is a temperature measuring thermocouple (10) arranged on the inner surface and the outer surface of the boiler tube (8).
5. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 1, wherein:
the inner wall of the inner cavity (7) is coated with a high-temperature-resistant ceramic coating.
6. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 1, wherein:
the workpiece support (9) is made of high-temperature-resistant ceramic material.
7. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 1, wherein: and a cooling assembly used for cooling the sealing washer is arranged in the cover body of the sealing cover (6).
8. The apparatus for simultaneously pre-oxidizing the inner and outer walls of a boiler tube according to claim 7, wherein:
the cooling assembly is a spiral coil (3) arranged along the inside of the cover body, a water inlet hole (4) and a water outlet hole (5) are formed in the sealing cover (6), and the water inlet hole (4) and the water outlet hole (5) are connected with a water inlet and a water outlet of the spiral coil (3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121986750.2U CN215713313U (en) | 2021-08-23 | 2021-08-23 | Device for simultaneously pre-oxidizing inner and outer walls of boiler tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121986750.2U CN215713313U (en) | 2021-08-23 | 2021-08-23 | Device for simultaneously pre-oxidizing inner and outer walls of boiler tube |
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| Publication Number | Publication Date |
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| CN215713313U true CN215713313U (en) | 2022-02-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202121986750.2U Active CN215713313U (en) | 2021-08-23 | 2021-08-23 | Device for simultaneously pre-oxidizing inner and outer walls of boiler tube |
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| CN (1) | CN215713313U (en) |
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2021
- 2021-08-23 CN CN202121986750.2U patent/CN215713313U/en active Active
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