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A method for surface modification of inner and outer walls of austenitic steel boiler tubes

A technology of surface modification and austenitic steel, which is applied in the field of surface modification of the inner and outer walls of austenitic steel boiler tubes, can solve the problems such as the decline of the oxidation resistance of the alloy, the peeling of the oxide film, and the peeling of the alloy oxide film. Significant corrosion effect, improved surface roughness, and improved bonding effect

Active Publication Date: 2019-07-30
HUANENG POWER INT INC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But Cr 2 o 3 The stability in steam above 600°C is poor, and the oxide film loosening caused by volatile products will cause the oxide film to peel off, and further lead to pipe plugging and pipe explosion accidents; in addition, the Cr content in the alloy matrix is ​​relatively low, and the With the increase of service time, when the Cr content required for the growth of oxide film cannot be supplemented, the oxidation resistance of the alloy will also drop sharply
Therefore, the two technologies can only improve the oxidation resistance of the alloy in a short period of time at the initial stage of service, and cannot fundamentally solve the problems of alloy oxidation and oxide film peeling
[0010] There is currently no technology capable of addressing both steam side and flue gas side oxidation / corrosion of austenitic steel boiler tubes

Method used

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  • A method for surface modification of inner and outer walls of austenitic steel boiler tubes
  • A method for surface modification of inner and outer walls of austenitic steel boiler tubes
  • A method for surface modification of inner and outer walls of austenitic steel boiler tubes

Examples

Experimental program
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Embodiment 1

[0044] The instruments and reagents used in the following examples are all commercially available. The pipe matrix used in the examples is the Super 304H (produced by Baosteel) boiler pipe in the state of delivery. The specific implementation process is as follows:

[0045] (1) Fully stir the mixed inner wall spraying slurry and outer wall spraying slurry respectively, then put the slurry into the ball ceramic tank, and plug the gap between the aluminum-silicon slurry bottle and the porcelain tank with a soft cloth , place the porcelain jar on a ball mill, and ball mill for 10 hours to obtain the ball-milled slurry.

[0046] Among them, the inner wall coating slurry consists of 40wt.% metal mixed powder, 35wt.% cellulose acetate and aluminum dihydrogen phosphate mixed solution (the mass ratio of cellulose acetate to aluminum dihydrogen phosphate is 1:1), 2wt.% chromic anhydride and the remainder of water. Among them, the mixed metal powder contains 55wt.% aluminum powder, 2...

Embodiment 2

[0057] The pipe matrix used in Example 2 is the Super 304H (produced by Baosteel) boiler pipe in the state of delivery. The specific implementation process is the same as in Example 1. The surface modification parameters and the structural characteristics of the modified inner and outer walls are shown in the following table 1:

[0058] Table 1 Example 2 Boiler tube surface modification parameters and structural characteristics of the modified layer on the inner and outer walls after modification

[0059]

Embodiment 3

[0061] The pipe matrix used in Example 3 is the supplied state TP347HFG (produced by Baosteel) boiler pipe. The specific implementation process is the same as in Example 1. The surface modification parameters and the structural characteristics of the modified inner and outer walls are shown in the following table 2:

[0062] Table 2 Example 3 Boiler Tube Surface Modification Parameters and Structure Characteristics of the Modified Layer on the Inner and Outer Walls after Modification

[0063]

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Abstract

The invention provides a method for modifying inner and outer wall surfaces of an austenitic steel boiler pipe. The method comprises the steps of applying inner wall coating slurry to the inner wall of the boiler pipe for 0.01-0.05 mm in thickness, and applying outer wall coating slurry to the outer wall of the boiler pipe for 0.01-0.05 mm in thickness; repeating the application process after drying till the thickness of the inner and outer wall coatings of the boiler pipe reaches 0.05-1 mm; finally conducting pickling after sintering. The method provided by the invention has the advantages of simple process, low cost and high production efficiency, and applies to the austenitic steel boiler pipe with small caliber and great length; and the anti-oxidation / anti-corrosion effect of the modified surface of the boiler pipe is obvious, and the structure and strength of alloy matrix are not changed.

Description

technical field [0001] The invention relates to the technical field of surface alloying and coating, in particular to a method for modifying the inner and outer walls of austenitic steel boiler tubes. Background technique [0002] Boiler tubes are the key components in the boiler that are responsible for recovering the energy of coal-fired flue gas, heating steam, and realizing energy conversion. The corrosion suffered by the heating surface mainly comes from the oxidation corrosion of high temperature steam inside the furnace tube and the flue gas corrosion caused by the combustion of pulverized coal outside the furnace tube. [0003] Due to the differences in boiler equipment structural materials, operating modes and combustion coal types, the high-temperature corrosion on the flue gas side is more complicated. In the reported boiler accidents in recent years, the metal corrosion (scale peeling, pitting corrosion, sulfur corrosion, fly ash blowing damage and stress corros...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F7/04B22F5/12B22F1/00
CPCB22F1/0003B22F5/106B22F7/04
Inventor 鲁金涛李卫东黄锦阳杨珍周永莉党莹樱赵新宝严靖博尹宏飞袁勇
Owner HUANENG POWER INT INC