Causes and control measures of seamless boiler tube leakage ​

Seamless boiler tubes are hollow steel components with open ends, critical for power plants, particularly in the main pressure-bearing parts of boilers, including economizer tubes, water wall tubes, superheater tubes, and reheater tubes (collectively known as "the four tubes"). These tubes perform key functions such as heating feedwater and steam, and their failure can lead to costly shutdowns and severe damage.

Causes of Boiler Tube Leakage

- Erosion:

Flue gases in coal-fired boilers carry fly ash particles that erode tube walls over time, thinning them and causing leaks. Factors affecting erosion include:

Fly ash velocity: Erosion is directly proportional to the cube of ash velocity.

Fly ash concentration: Higher concentrations lead to more wear.

Particle characteristics: Coarse, hard ash particles cause more damage.

- High-Temperature Corrosion:

Occurs mainly in water walls near the furnace, aggravated by poor combustion, hydrogen sulfide presence, and the formation of molten ash layers. This can lead to severe corrosion and tube rupture.

- Poor Water Circulation:

Long-term low-load operations in power plants cause poor water circulation, leading to tube overheating and eventual leakage.

- Mechanical Damage:

Poor maintenance practices or improper use of tools can weaken the tube surfaces, leading to rupture under pressure.

- Unscientific Boiler Design:

Poorly designed boilers may not account for the stresses on water walls, leading to failures at suspension points under high pressure.

Control Measures to Prevent Tube Leakage

- Anti-Wear and Anti-Corrosion Measures:

Use new materials and technologies to improve tube durability, such as wear-resistant plates on economizers and corrosion-resistant materials on water wall tubes.

- Improved Operation Management:

Monitor overheating, control temperature fluctuations, and ensure stable combustion. Regular analysis of overheating phenomena helps prevent unexpected leaks.

- Regular Inspection:

Conduct thorough inspections of economizers, water walls, and superheaters, checking for erosion, corrosion, and tube swelling. Preventive maintenance is key.

- Maintenance Personnel Training:

Train maintenance teams to properly inspect and repair tubes, reducing human errors that lead to leaks.

- Improved Boiler Design:

Optimize heat surface layout and material selection to prevent future tube failures, reducing incidents of leakage and rupture. Recent design improvements in new power plant units have significantly decreased leakage occurrences.

By addressing these issues, seamless boiler tube failures can be minimized, ensuring safer and more efficient power plant operations.