Abstract The problem of ammonium bisulfate (ABS) deposition blocking and corroding air preheaters and economizers in boilers became severe, as the selective catalyst reduction (SCR) system was widely used in the coal-fired boilers to meet the stringent nitrogen oxide (NOX) discharge standard. In this study, an online digital image technique was applied to investigate the growth of the deposition of fly ash and ABS blend in a drop tube furnace (DTF). The deposition was measured on a temperature controlled deposition probe. The results of the image technique showed that the surface temperature of the deposition probe had a negative effect on stable thicknesses of the blend depositions and the stable thicknesses for cases 1 (553 K), 2 (513 K), and 3 (473 K) are 4.78, 5.26, and 7.64 mm, respectively. Meanwhile, the relative variation of the heat flux QR for Cases 1, 2, and 3 are 17.8%, 33.8%, and 40.2%. The deposition in the lower deposition surface temperature has a greater effect on the heat transfer efficiency. In order to understand the deposition formation of fly ash and ABS blend, the X-ray diffraction (XRD), X-ray fluorescence (XRF), and the scanning electron microscopy (SEM) analysis were undertaken of the blend deposition. The results indicated that the content of ABS in the bottom part deposition increased as the probe surface temperature decreases, and this would result in more agglomerates in the deposition according to the observations of the SEM and the growth behavior of the deposition was influenced. Meanwhile, the results show that the deposition characteristics of ABS and fly ash blend is strongly influenced by the distribution and the condensation behavior of ABS. This work makes a contribution to a deeper understanding of deposition characteristics of ammonium bisulfate and fly ash blend, which is important for boilers to control the blend deposition in air preheaters and economizers.

中文翻译：

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使用在线数字图像技术研究硫酸氢铵和粉煤灰混合物的沉积特性：沉积表面温度的影响

摘要 燃煤锅炉广泛采用选择性催化还原（SCR）系统以满足严格的氮氧化物（NOX）排放要求，硫酸氢铵（ABS）沉积堵塞和腐蚀锅炉空气预热器和省煤器的问题日益突出。标准。在这项研究中，在线数字图像技术被应用于研究飞灰和 ABS 混合物在下降管式炉 (DTF) 中沉积的增长。在温度受控的沉积探针上测量沉积。图像技术的结果表明，沉积探针的表面温度对混合沉积物的稳定厚度和情况 1 (553 K)、2 (513 K) 和 3 (473 K) 的稳定厚度有负面影响分别为 4.78、5.26 和 7.64 毫米。同时，案例 1、2 和 3 的热通量 QR 的相对变化为 17.8%、33.8% 和 40.2%。在较低的沉积表面温度下沉积对传热效率的影响更大。为了了解粉煤灰和 ABS 共混物的沉积形成，对共混物沉积进行了 X 射线衍射 (XRD)、X 射线荧光 (XRF) 和扫描电子显微镜 (SEM) 分析。结果表明，随着探针表面温度的降低，底部沉积物中ABS的含量增加，根据SEM观察，这将导致沉积物中更多的团聚体并且影响沉积物的生长行为。同时，结果表明，ABS 和粉煤灰混合物的沉积特性受 ABS 的分布和冷凝行为的强烈影响。这项工作有助于更深入地了解硫酸氢铵和粉煤灰混合物的沉积特性，这对于锅炉控制空气预热器和省煤器中的混合物沉积具有重要意义。