Heat exchange tube of waste heat boiler

Patent metadata

Field	Value
Publication number	US-11796170-B2
Application number	US-202217723408-A
Country	US
Kind code	B2
Filing date	Apr 18, 2022
Priority date	Oct 18, 2019
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

Disclosed is a heat exchange tube of waste heat boiler, which includes a tube body. The outer surface of the tube body is sprayed with a layer of anti-corrosion coating. The components of the anti-corrosion coating are Al 2 O 3 , CaAl 2 O 4 and Ca 3 (PO 4 ) 2 . On the surface of nano anti-corrosion coating, HF reacts with Al 2 O 3 , CaAl 2 O 4 and Ca 3 (PO 4 ) 2 to form AlF 3 and Ca 5 (PO 4 ) 3 F, which are tightly wrapped on the surface of the coating, thereby effectively preventing HF from corroding the interior of the coating and the heat exchange tube. Meanwhile, due to the anti-corrosion coating with the specific composition of the present disclosure, the heat exchange tube of the present disclosure can be resistant to fluorine corrosion at a high temperature of 600° C. or more, and can be used at a rather high temperature of 1000° C. or more.

First claim

What is claimed is:

1. A heat exchange tube of waste heat boiler, comprising a tube body, wherein an outer surface of the tube body is sprayed with a layer of anti-corrosion coating, components of the anti-corrosion coating are Al 2 O 3 , CaAl 2 O 4 and Ca 3 (PO 4 ) 2 ;
wherein ingredients of the anti-corrosion coating comprise nano-alumina, calcium aluminate, calcium phosphate, nano-aluminum powder and nano-alumina sol; and
wherein a ratio of the ingredients in parts by mass, is: 40 to 50 parts of nano-alumina, 5 to 10 parts of calcium aluminate, 5 to 10 parts of calcium phosphate, 20 to 30 parts of nano-aluminum powder; and 10 to 20 parts of nano-alumina sol are added into a mixture of the ingredients and evenly dispersed.

2. The heat exchange tube of waste heat boiler according to claim 1 , wherein respective proportions of the Al 2 O 3 , the CaAl 2 O 4 and the Ca 3 (PO 4 ) 2 in the anti-corrosion coating are respectively 80% to 90%, 5% to 10% and 5% to 10%.

3. The heat exchange tube of waste heat boiler according to claim 1 , wherein the anti-corrosion coating has a thickness of 1 to 2 mm.

4. The heat exchange tube of waste heat boiler according to claim 1 , wherein the anti-corrosion coating is formed by a method comprising:
pretreating an outer surface of the tube body by sandblasting;
spraying a mixture of the alumina sol and a uniform mixture of the ingredients on the outer surface of the heat exchange tube pretreated by sandblasting; and
forming the anti-corrosion coating on the outer surface of the tube body by leveling and low-temperature baking.

5. The heat exchange tube of waste heat boiler according to claim 4 , wherein a baking temperature is ranged from 200 to 300° C.

6. The heat exchange tube of waste heat boiler according to claim 1 , wherein a plurality of annular ribs are provided on an inner wall of the tube body.

7. The heat exchange tube of waste heat boiler according to claim 6 , wherein the annular ribs are mounted on an inner surface of the tube body by a plurality of support columns, and the support columns penetrate all the annular ribs in sequence.

8. The heat exchange tube of waste heat boiler according to claim 1 , wherein a particle size range of the nano-alumina is 10 to 30 nm.

9. The heat exchange tube of waste heat boiler according to claim 1 , wherein a particle size range of the nano-aluminum powder is 20 to 100 nm.

10. The heat exchange tube of waste heat boiler according to claim 1 , wherein a solid content of the nano-alumina sol is 20% to 25%.

11. The heat exchange tube of waste heat boiler according to claim 1 , wherein a particle size of the nano-alumina sol is 10 to 15 nm.

12. The heat exchange tube of waste heat boiler according to claim 1 , wherein a pH value of the nano-alumina sol is 4 to 5.

13. The heat exchange tube of waste heat boiler according to claim 1 , wherein calcium aluminate and calcium phosphate purity is equal to or greater than 99%.

Assignees

• Univ Zhejiang

Inventors

• Ma Zengyi
• Yan Jianhua
• Zhang Yike
• Li Wenhan
• Gao Ruofeng
• Chen Zhe
• Cai Yaming
• Zhong Pucheng

Classifications

• F22B37/025 Primary

  Devices and methods for diminishing corrosion, e.g. by preventing cooling beneath the dew point · CPC title

• F22B37/04

  and characterised by material, e.g. use of special steel alloy · CPC title

• F22B37/06

  Flue or fire tubes; Accessories therefor, e.g. fire-tube inserts · CPC title

• F28F1/40 Primary

  the means being only inside the tubular element · CPC title

• F16L58/14 Primary

  by ceramic or vitreous materials · CPC title