Failure analysis of the flash evaporator in an alumina production plant

Abstract

1. IntroductionFlash evaporator is one of the key equipments used in alumina production [1]. Usually flash evaporating system iscomposed of multiple flash evaporators, this is the so-called multi-stage flash evaporating system. The multi-stage flashevaporating system can recycle the thermal energy produced by steam exhaust and facilitate the next level process forreceiving the supplies with low temperature and low pressure.Due to the worse working environments (high temperature, high pressure, corrosive environments), it is hard to controlthe failure of the flash evaporator. Many failures of flash evaporator still happened even though many efforts were made inthis aspect [2–6]. On the other hand, the root cause of different cases might not be the same. Therefore, it is necessary toinvestigate every case in detail in order to prevent the similar failures in the future.In this case study, a ten-stage ore pulp flash evaporator used in analumina production plant was investigatedin order tofind outitsrootcause.Themacroscopicobservations,metallurgicalobservations,microscopicobservationsandEDSanalysiswere performed in this study. In the end, the failure cause was concluded by analyzing the experimental results.2. BackgroundsBackgrounds areofgreatimportanceforinvestigatingthefailurecauseofacase[7].Therefore,itisnecessarytocollectasmuch aspossibletheinformationonthebackgroundsofthefailedflashevaporator.Thisten-stagepulpflashevaporatorwas