阅读说明：本技术 一种同时提高电站锅炉管内外壁耐蚀性能的方法及装置 (Method and device for simultaneously improving corrosion resistance of inner wall and outer wall of power station boiler tube ) 是由 杨珍 屠亮 杨征 张醒兴 鲁金涛 黄锦阳 周永莉 谷月峰 袁勇 于 2021-08-23 设计创作，主要内容包括：一种同时提高电站锅炉管内外壁耐蚀性能的方法及装置,通过对锅炉管进行表面处理；在真空环境中,对表面处理后的锅炉管进行加热,使其发生预氧化反应；将预氧化反应之后的锅炉管进行冷却,然后通入空气,得到内表面和外表面同时发生选择性氧化产生致密预氧化膜的锅炉管。装置包括由壳体与密封盖组成的反应室,反应室的外周设有加热装置；反应室的内腔中设有用于放置锅炉管的工件支架以及用于测量锅炉管表面温度的测温装置,壳体上开设抽真空接口；密封盖的盖体内部设有螺旋盘管,密封盖上开设有进水孔和出水孔,进水孔和出水孔与螺旋盘管的进水口和出水口相接。本发明不会损害锅炉管基体的力学性能,且工艺简单高效、环境友好。(A method and device for improving the corrosion resistance of the inner and outer walls of a boiler tube of a power station at the same time, by carrying out surface treatment on the boiler tube; 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 device 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 is arranged on the shell; the inside spiral coil pipe that is equipped with of the lid of sealed lid, sealed covering has seted up inlet opening and apopore, and inlet opening and apopore meet with spiral coil pipe's water inlet and delivery port. The invention does not damage the mechanical property of the boiler tube matrix, and has simple and efficient process and environmental protection.)

1. A method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of a boiler tube of a power station is characterized by comprising the following steps:

-surface treating the boiler tubes (8);

-heating the surface treated boiler tubes (8) in a vacuum environment for pre-oxidation;

-cooling the boiler tubes (8) after the pre-oxidation reaction, and then introducing air to obtain the boiler tubes (8) with the inner surface and the outer surface being selectively oxidized simultaneously to generate a dense pre-oxidation film.

2. The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 1, characterized in that: the axial temperature distribution of the inner surface and the outer surface of the boiler tube (8) is uniform in the heating process.

3. The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 1, characterized in that: the boiler pipe (8) is made of austenitic heat-resistant steel, and the dense pre-oxidation film is Cr₂O₃And (3) a membrane.

4. The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 1, characterized in that: the surface treatment enables the surface quality of the boiler pipe (8) to meet the requirements of GB5310-2008 'seamless steel pipe for high-pressure boiler'.

5. The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 1 or 4, characterized in that:

the surface treatment is carried out by sand blowing treatment or acid washing treatment.

6. The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 1, characterized in that:

the vacuum degree of the vacuum environment is 10^-2～10^-4Pa, in the range of Pa.

7. The method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 1, characterized in that: the temperature of the pre-oxidation reaction is not higher than the pipe tempering temperature of the boiler pipe (8), and the time of the pre-oxidation reaction is 10-60 min.

8. The utility model provides a improve power plant boiler pipe inside and outside wall corrosion resistance's device 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) is arranged on the shell (2); the spiral coil (3) is arranged in the cover body of the sealing cover (6), the water inlet hole (4) and the 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 the water inlet and the water outlet of the spiral coil (3).

9. The device for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 8, characterized in that: the heating device is an induction heating coil (1), 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 coil (1) is axially and uniformly arranged on the periphery of the reaction chamber along the boiler tube (8).

10. The device for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the power station boiler tube according to claim 8, characterized in that: the temperature measuring device is a temperature measuring thermocouple (10) arranged on the inner surface and the outer surface of the boiler tube (8).

Technical Field

The invention belongs to the field of boiler tubes, and relates to a method and a device for simultaneously improving the corrosion resistance of inner and outer walls of a power station boiler tube.

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) modifying the surface of boiler tube, aluminizing or chromium plating to form rich Al or Cr protecting coating on the surface of boiler tube, and making the boilerThe surface of the furnace tube quickly forms 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.

Disclosure of Invention

The invention aims to solve the problem of poor effect of improving the corrosion resistance of the boiler tube in the prior art, and provides a method and a device for simultaneously improving the corrosion resistance of the inner wall and the outer wall of the boiler tube of a power station, so that the mechanical property of a boiler tube matrix is not damaged on the basis of improving the corrosion resistance, and the method and the device are simple in process, efficient and environment-friendly.

In order to achieve the purpose, the invention has the following technical scheme:

a method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of a boiler tube of a power station comprises the following steps:

-surface treating the boiler tubes;

heating the surface-treated boiler tube in a vacuum environment to perform a pre-oxidation reaction;

cooling the boiler tube after the pre-oxidation reaction, and then introducing air to obtain the boiler tube with the inner surface and the outer surface being selectively oxidized simultaneously to generate a dense pre-oxidation film.

Preferably, the axial temperature distribution of the inner and outer surfaces of the boiler tubes is made uniform during the heating process.

Preferably, the boiler tube is made of austenitic heat-resistant steel, and the dense pre-oxidation film is Cr₂O₃And (3) a membrane.

Preferably, the surface treatment enables the surface quality of the boiler tube to meet the requirements of GB5310-2008 'seamless steel tube for high-pressure boiler'.

Preferably, the surface treatment is performed by sand blasting or acid washing.

Preferably, the vacuum degree of the vacuum environment is 10^-2～10^-4Pa, in the range of Pa.

Preferably, the temperature of the pre-oxidation reaction is not higher than the tempering temperature of the tube of the boiler tube, and the time of the pre-oxidation reaction is 10-60 min.

A device for simultaneously improving the corrosion resistance of the inner wall and the outer wall of a power station boiler tube 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 is arranged on the shell; the inside spiral coil pipe that is equipped with of the lid of sealed lid, sealed covering has seted up inlet opening and apopore, and inlet opening and apopore meet with spiral coil pipe's water inlet and delivery port.

Preferably, the heating device is an induction heating coil, 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 coil is 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.

Compared with the prior art, the invention has the following beneficial effects: the inner surface and the outer surface of the boiler tube are selectively oxidized simultaneously in a low vacuum environment to form a compact pre-oxidation film, so that the diffusion of oxygen-containing anions and metal cations through the oxidation film is effectively prevented, and the corrosion resistance of the inner wall and the outer wall of the boiler tube is improved. The pre-oxidation reaction of the invention is carried out in a low vacuum environment, and the invention 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 invention 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 invention 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 invention provides a method for simultaneously improving the corrosion resistance of the inner wall and the outer wall of a power station boiler tube, which 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^{- 3}Pa；

(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 are not intended to limit the technical solution of the present invention, and it should be understood by those skilled in the art that the technical solution can be modified and replaced by a plurality of simple modifications and replacements without departing from the spirit and principle of the present invention, and the modifications and replacements also fall into the protection scope covered by the claims.