411 / 2018-12-26 15:27:04

Investigation on Oxidation Behavior of Super304H and HR3C Steel in High Temperature Steam from a 1000MW Ultra-supercritical Coal-fired Boiler

stainless steel; Super304H; HR3C; steam oxidation; ultra-supercritical boiler

全体主题 > 锅炉

电站锅炉超超临界技术提高了锅炉运行时的蒸汽压力和温度，有效增加锅炉效率并减少污染物排放。但是，蒸汽温度的提高加快了换热器蒸汽侧材料的氧化速率，而氧化层的剥落，则会影响电站的组件寿命和整体效率，因此，电站锅炉超超临界技术的应用，对高温受热面材料的高温抗蒸汽氧化性能提出了更高要求。本文主要研究1000MW超超临界锅炉中Super 304H和HR3C两种耐热钢在长期（17973小时）真实环境服役下的高温蒸汽氧化性能。运用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱分析仪(EDS)对运行管样品进行表征，研究结果表明：Super304H耐热钢样品蒸汽氧化层表面多为Fe2O3，Cr2O3和FeCr2O4，氧化层厚度为50-70μm；HR3C耐热钢样品的氧化层表面化合物为Fe2O3，氧化层厚度在20μm左右，但部分位置却有40μm深的点蚀。两种材料的蒸汽氧化层均呈两层结构，其中氧化外层富集O和Fe元素，氧化内层富集O和Cr元素。与HR3C耐热钢样品相比，Super 304H耐热钢样品蒸汽氧化表面存在氧化层剥落现象，剥落位置位于氧化内外层间的界面。造成两种耐热钢蒸汽氧化性能差异的主要原因是，材料中Cr和Ni的含量差异以及锅炉运行的周期波动。

Increasing steam parameters (pressure and temperature) of utility boilers can effectively improve fossil energy utilization and reduce pollutant emissions. The increase of steam temperature leads to an accelerated material oxidation rate, and the oxidation scale will peel off as its thickness increases, as well as affect the component life and overall efficiency of the boiler. The application of ultra-supercritical technology puts higher requirements on the steam oxidation resistance of high temperature heating surface materials. Oxidation behavior of Super304H and HR3C steel in high temperature steam from an ultra-supercritical coal-fired boiler was investigated in this paper. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The results showed that the oxidation surface of Super304H were composed of Fe2O3, Cr2O3 and FeCr2O4, the oxidation scale had a thickness of 50-70μm. In addition, the oxidation surface of HR3C were composed of Fe2O3, the oxidation scale was about 20μm in thickness and contained few pitting. The corrosion scale of the two samples could be divided into two layers, including outer layer enriched O element and Fe element, and inner layer enriched O element and Cr element. Furthermore, oxidation scale spalling was observed on the surface of Super304H sample.