Abstract:

With large-scale renewable power integrated into the grid, the status of traditional thermal power units as energy allocation has been significantly enhanced. The safety and stability of boiler peak-shaving operation become more and more important. This work coupled the heat absorption with the hydrodynamic characteristics and forms the temperature calculation model of water-cooled wall. Meanwhile, a SO _x generation model was developed to determine the process of the fuel sulfur release in a reducing atmosphere and the mutual transformation of sulfur components. Based on the numerical simulation of furnace, the temperature calculation model of water-cooled wall and the tube wall high-temperature corrosion model with time dimension, a high-temperature corrosion prediction model of water-cooled wall for boiler peak-shaving operation was proposed. The corresponding software was also developed using the Matlab GUI platform. A supercritical 600MW tangentially coal-fired boiler was selected as the research object. The results showed that the accuracies of the wall temperature distribution and H₂S concentration distribution near the wall obtained by coupling calculation of wall temperature and SO _x generation model were high, which provided a good basis for accurate prediction of high-temperature corrosion. The high-temperature corrosion characteristics of the water-cooled wall under different loads were different. The corrosion degree of the water-cooled wall decreases with the decrease of the boiler loaded as a whole. The area of front wall between the burner zone and SOFA zone was the most severely corroded under 100% BMCR and 75% THA load, with maximum corrosion depths of 276μm and 233μm per year, respectively. The high-temperature corrosion depths under 50% THA and 35% BMCR load rapidly increased to a maximum in the top of the burner zone, which were 224μm and 256μm per year, respectively. The high-temperature corrosion state of the water-cooled wall under multiple working operation was manifested as the spatio-temporal superposition of the corrosion state of each working condition. The spatio-temporal distribution of the high-temperature corrosion state of water-cooled wall could be predicted by boiler operation parameters and operation time through the prediction software.

Key words: peak-shaving operation, water-cooled wall, high-temperature corrosion, numerical simulation, wall temperature calculation

摘要：

随着可再生能源大规模并网，传统火电机组作为调配能源的地位显著增强，这对锅炉灵活调峰运行的安全稳定性提出了更高要求。本文耦合烟气侧与工质侧传热，结合管壁温计算，形成水冷壁壁温分布耦合计算方法。同时，建立了用于确定还原性气氛下的燃料硫释放以及含硫组分的相互转化过程的SO _x 生成模型。综合炉膛数值模拟、水冷壁壁温耦合计算以及包含时间维度的管壁高温腐蚀模型，提出了一种适应锅炉调峰运行的水冷壁高温腐蚀预测模型并基于Matlab GUI开发了对应软件。选取一台超临界600MW四角切圆燃煤锅炉为研究对象，结果表明：采用壁温耦合计算模型和SO _x 生成模型得到水冷壁的壁温分布和近壁面H₂S浓度分布准确度高，为水冷壁高温腐蚀的准确预测提供了良好基础。不同负荷下水冷壁高温腐蚀特征存在差异，壁面腐蚀程度整体上随负荷降低而降低。100%BMCR与75%THA负荷下前墙水冷壁燃烧器与SOFA之间的区域腐蚀最为严重，最大年腐蚀深度分别为276μm和233μm；50%THA与35%BMCR负荷下高温腐蚀深度在燃烧器区域的上部迅速增加至最大值，分别为224μm和256μm。多工况运行水冷壁高温腐蚀状态表现为各工况腐蚀状态的时空叠加。运用水冷壁高温腐蚀预测模型可实现通过锅炉运行参数和运行时间预测多工况下水冷壁高温腐蚀状态程度的时空分布。

关键词: 调峰运行, 水冷壁, 高温腐蚀, 数值模拟, 壁温计算