Study On Failure Mode And Risk Estimation For Pressure Parts Of Power Plant Boiler

Electricity is the lifeblood of the national economy, while thermal power, as the country’s main energy supply, plays an important role in the development of the national economy. As the core equipment of utility boiler in the thermal power plant, whether it is safe and reliable or not has a great influence on the national economy. In order to guarantee the safe operation of the boiler, it’s important to study and analyze the failure modes of the boiler pressure parts, identifying failure modes and mechanism for each boiler pressure parts and finding out the main failure of the site, by which we can make targeted prevention and management, reasonable arrangements for boiler inspection and maintenance, thus reduce boiler accident.In this paper, utility boiler pressure parts are studied systematacially, and the utility station boiler pressure parts are categorized into water wall, economizer, superheater and reheater, steam drum, header, desuperheater, boiler tubes, high temperature and high pressure valves. Also in this paper, with the combination of theoretical analysis and engineering practice, failure modes, failure mechanisms and common failure parts of each component are deeply analyzed. During the analysis, physical appearance and organization phase diagram of various failure modes are given, which make it vivid intuitive and easy to understand. Meanwhile, combining engineering practice, typical case of boiler pressure parts failures are introduced and analyzed.After a longtime operation, each pressure part will be in varying degrees of damage, especially when the boilers are started and stopped frequently, under great parameter fluctuations or operating under high parameter, the extent of the damage will be more severe. Common injury pattern of boiler pressure parts are creep, fatigue, wear, corrosion and so on. Different parts, under different conditions, have different injury patterns. Some parts have a single injury pattern, while some parts have both the different injury patterns. In allusion to the different injury patterns of various boiler pressure parts, this paper gives corresponding calculation method of life assessment. As for the same model injury, this paper also gives the different calculation methods. Through life assessment, the boiler’s security situation is evaluated reasonably, which make it possible to take preventive measures to avoid accidents.Risk assessment and risk-based testing is an emerging technology, the application of this technology can improve the scientificity and effectiveness of device management and inspection. Applied in utility boiler management and inspection, this technology can not only realize reasonable control of the equipment management as well as inspection overall cost, but also effectively improve the equipment’s management safety level and reduce the risk of accidents. This paper introduces and studies this technique to explore the risk assessment and risk-based testing on the specific application in utility boilers.Failure modes, failure analysis, life assessment and risk assessment of boiler pressure parts are complementary. Through the analysis of failure modes and failure mechanisms of boiler pressure parts, the main failure parts modes can be identified, then it can be applied to the boiler inspection and management, improving its scientificity and effectiveness as well as providing accurate and reliable data for the life assessment and risk assessments. Meanwhile, the life assessment and risk assessment are applied to evaluate the boiler’s safety situation, and then improve the safety situation by effective measures, reducing the risk level and avoiding boiler accidents. And the focus and direction for the next step of inspection and management are also indicated.