Advancements and Insights in High-Parameter Boiler Header Research

Why analyze the high parameter boiler header?

With the rapid development of thermal power technology, the country’s requirements for coal consumption indicators are getting lower and lower and the introduction of environmental protection policies are also higher standards, high parameter, large capacity, low emission power plants continue to emerge, the operating pressure and temperature of the unit is getting higher and higher, ultra (ultra) critical large-capacity parameter unit has become the main direction of the current technical research. Moreover, with the improvement of new energy and clean energy retention, in order to ensure the utilization of these new energy and clean energy, the frequency of thermal power unit peaking has become more and more frequent, and unit peaking has also become normalized.

Boiler equipment as one of the important thermal power plant host equipment, the strength of its pressure parts, safety, reliability and equipment life and other issues continue to emerge, the power industry investors and manufacturing companies are also paying more and more attention to this and concern, safety and reliability is gradually becoming an important factor in the evaluation of the host of the power plant investor, especially when the boiler. Therefore, every year, the Energy Bureau and China Light and Power Union (CLP) not only release the report of thermal power unit energy efficiency benchmarking competition, but also the reliability benchmarking competition report.

With the thermal power industry’s overcapacity, power equipment market prices continue to go down, how to ensure safety and reliability under the premise of minimizing the cost of boiler equipment has become a manufacturing plant to think about the problem. At present, the boiler plant has been from procurement, design, process and manufacturing of various sources of cost reduction and efficiency.

As an important pressurized component in the power station boiler system, it is particularly important to ensure its safe and reliable operation. The strength analysis of boiler header as an important basis for header box design, especially in the high parameter, frequency peaking and low-cost market environment, boiler header strength analysis and design research helps practitioners to scientifically and rationally apply the codes and standards for header box design.

Let’s dive into the research status of high-parameter boiler headers.

Back in 1880, the American Society of Mechanical Engineers, or ASME, was established in the United States. The primary motivation behind forming this association was a series of boiler explosions, numbering nearly 10,000, that occurred in the United States and Canada up until 1990. To mitigate the risk of such explosions, the American Society of Mechanical Engineers established the Boiler Code Committee in 1911. As a result, in 1915, the first ASME Boiler Code was introduced. This code encompassed aspects of boiler design, manufacturing, and inspection. Over a century later, ASME Boiler Code has continued to evolve and improve through continuous refinements by the committee.

To maintain the code’s relevance, it was initially updated every three years and received annual additions until 2010. After that, it transitioned to updates every two years, without annual additions. Annual meetings are now regularly organized to review, modify, and respond to the code. ASME Boiler Pressure Vessel Code has played a pivotal role in reducing boiler explosions and guiding more rational and cost-effective boiler design and manufacturing practices.

In China, boiler safety technology supervision regulations dictate that boiler pressurized elements’ strength can be calculated and calibrated following GB/T 9222, titled “Calculation of Pressurized Element Strength of Water Tube Boilers.” This standard, which has undergone several updates since its inception, has a relatively slower update pace compared to the ASME standard. ASME BPVC.VIII.2 has established a comprehensive system of stress analysis guidelines and finite element calculation methods, continually updated to align with technological advancements. On the other hand, GB/T 9222-2008 offers a simpler description of stress analysis principles and verification methods.

Strength theory is fundamental to understanding how materials behave under stress, encompassing criteria for yield, fracture, fatigue, and stability. It serves as a cornerstone for material mechanics, engineering applications, and structural design. Selecting the right strength theory is crucial in ensuring accurate and reasonable strength calculations and designs. Among the many proposed models and guidelines, Yu Maohong’s double shear strength theory is widely accepted. Researchers like Ao Wengang et al. have employed this theory to study thick-walled cylinders, yielding valuable elastic-plastic analysis results.

Boiler header opening receivers involve complex problems related to cylindrical shell openings. In the 1980s, Professor Steele initiated research in this area, using an approximate solution based on Donnell flat shell equations, which is still employed in European Union standards. Du Qinghai and Xue Mingde, building on thin shell theory, solved Morley’s equation, incorporating a correction term. This led to a more accurate theoretical analytical solution under internal pressure and an expanded applicable range of opening ratios, reaching 0.93. Their work culminated in a stress index curve for cylindrical radial opening receivers under internal pressure, simplifying strength calculations.

Since the mid-20th century, research into high-temperature material properties and the mechanisms of fatigue, creep, and their interaction has been extensive. Due to limited high-temperature experimental data, researchers often rely on extrapolation and simplifications. Predicting the fatigue and creep interaction of materials has been tackled through ductility models, such as one proposed by Goswami T. Wang Aimin has improved creep damage analysis methods for greater accuracy and simplicity in engineering applications. Nevertheless, high-temperature life assessment methods tend to be conservative, indicating the need for further theoretical research and experimentation.

[Boiler Header Source]

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