The structural integrity of ceramic candle filters is a key element for hot gas cleanup systems. Ceramic candle filters used in demonstration plants have experienced degradation and fracturing. Preliminary examination of these ceramic filters indicated that damage of the filters may have resulted from strength degradation due to persistent high temperature operation, thermal transient events, excessive ash accumulation and bridging, and pulse cleaning. This study proposes a nondestructive evaluation of the structural properties of these ceramic filters. The ceramic candle filter is a slender structure made of layers of porous materials. The structure has high acoustic attenuation, which has greatly limited the conventional acoustic emission or acoustic-ultrasonic detection capability. A virgin Refractron filter and twelve Schumacher filters which were previously tested under high pressure and high temperature at a demonstration power plant were evaluated. The acoustic signatures of the ceramic filters are established using a transient impact response technique. Results indicate that the natural frequencies of the filters can be used as an index to quantify the damage condition of the filters (Chen and Parthasarathy, 1996).;In order to confirm the dynamic response analysis, bending tests were performed to estimate the Young's modulus from the load-deflection curve and compared the results with the predicted values from vibration analysis. Four-point bending tests were conducted on seven intact filters, which included five used Schumacher filters, one new Schumacher filter and one new Refractron filter. Each ceramic candle filter was subjected to an applied load up to 40.7 lb. and the center deflection was measured using a digital transducer. The deflection was used to reflect the stiffness of ceramic filters. The bending test results can reflect the change of the stiffness among these filters and this change of stiffness matches with the observation from the vibration tests. To measure the deflection of ceramic candle filters one should conduct the tests in a quiet environment. Any small tremble will lead a large difference between theoretical and experimental results.
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机译：陶瓷蜡烛过滤器的结构完整性是热气净化系统的关键要素。示范工厂中使用的陶瓷烛式过滤器经历了降解和破裂。对这些陶瓷过滤器的初步检查表明，过滤器的损坏可能是由于持续高温操作，热瞬态事件，过多的灰分堆积和桥接以及脉冲清洁导致的强度降低所致。这项研究提出了对这些陶瓷过滤器的结构特性的无损评估。陶瓷烛式过滤器是由多孔材料层制成的细长结构。该结构具有高的声衰减，这极大地限制了常规的声发射或声-超声波检测能力。对原始折射滤光片和十二个舒马赫滤光片进行了评估，这些滤光片先前已在示范电厂进行了高压和高温测试。陶瓷过滤器的声学特征是使用瞬态冲击响应技术建立的。结果表明，滤波器的固有频率可以作为量化滤波器损坏状况的指标（Chen and Parthasarathy，1996）。为了确认动态响应分析，进行了弯曲试验以估计杨氏模量根据载荷-挠度曲线将结果与振动分析的预测值进行比较。对七个完整的滤镜进行了四点弯曲测试，其中包括五个二手的舒马赫滤镜，一个新的舒马赫滤镜和一个新的折射滤镜。每个陶瓷烛式过滤器承受的最大载荷为40.7磅，并使用数字传感器测量中心挠度。挠度用于反映陶瓷过滤器的刚度。弯曲测试结果可以反映这些过滤器之间的刚度变化，并且这种刚度变化与振动测试中的观察结果一致。要测量陶瓷烛式过滤器的挠度，应在安静的环境中进行测试。任何微小的颤动都会导致理论和实验结果之间的巨大差异。
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