59832 - Performance Modification of an Erosion-Damaged Large-Sized Centrifugal Fan 

Heavy-duty fans are employed in industrial processes where reliability has the same importance of performance. Despite the applications where fans are used for supply air from the environment to the process, many installations are characterized by operation with contaminated air and gas, sometimes characterized by high-temperature values, where the interaction between the fan internal surfaces and the contaminant affects the performance and the reliability of the entire machine. Contaminants, usually solid particles, are responsible for fouling and erosion issues, generating several drawbacks such as unbalance load, vibration, structural damage which are responsible for performance degradation, and earlier failure.

In the present paper, a large-sized centrifugal fan affected by solid particles is studied by numerical simulation. In particular, starting from the on-filed detections and the results coming from previous numerical analysis, the effects of implanted damages induced by the erosion process are analyzed in depth. Erosion-induced damages are characterized by the progressive reduction of the thickness of the fan internal walls and sometimes, the intensity of these phenomena is extremely high, and holes and discontinuities could affect the fan surfaces. In those cases, the fan operation is characterized by a different flow filed which induces performance modification and, also, the modification of the contaminant flow path. As commonly known, these machines are equipped with wear-resistant plates positioned in the regions which are more prone to erosion issues for a given operating condition that could become completely useless in the case of flow filed modification.

The results show how localized damage due to the erosion phenomenon at the fan inner cone could be responsible for the modification of fan performance (especially the efficiency) and, at the same time, for the modification of the more affected region by erodent particles. This investigation put the attention on the maintenance program and show how a localized issue could be responsible for larger damage, involving the structural integrity of the entire installation.