The Failure Mechanism Of Cyclone Separator To The Wall Cracks In FCC And Prevention

This paper is mainly to the research about the wall cracking defect on a FCC cyclone separator of YanChang Petroleum(group) refining&Petrochemical company, finds out the reasons why the wall crack, and puts forward the countermeasures so as to prevent the similar flange crack and failure to happen again.On the cracking failure of spiral separator taper cone section to the next section of the total length of4.9meters within the scope of multichannel irregular crack appears on the parent metal. The longest crack up to0.5meters, part of the surface crack width up to2mm, crack up to7-8mm, most belong to serious cracking failure. Cracks on the parent metal material of16MnR, thickness is10mm, inner lining20mm thick ceramic lining tortoiseshell net.There are many reasons for the cracking failure. Cyclone separator failure analysis related to the original design, manufacture, the usage environment, the raw materials used in supply and manufacturing, and many other factors. In order to know the causes of cyclone separator failure, this paper research from the above aspects one by one, analysis the detail of each factor, pay attention to identify the cause of the failure. To evaluate the material chemical composition, yield strength, tensile strength, impact toughness and so on, through the metallographic analysis, from the micro perspective to judgment the properties of the material. With making the metallographic sample, observe the material whether existence shrinkage, loose, segregation, different metal impurity, crack, white point, internal bubble defects, etc. Through the high magnification detection, test the material microstructure and predict the material whether contain oxidation, decarburization, corrosion, wear away, and the path of crack and so on. Through making the samples about tension test, impulse test, and determine the mechanical properties of the material. Also through the fracture analysis and comprehensive test to determine the causes of the failure of the cyclone separator.By using the finite element analysis method, construct the cyclone separator, model, mesh the model, apply loads, confirming boundary conditions, and solve the model. To get the flange equivalent stress and strain under the working condition, find out the position where thebiggest stress and strain appearing, combine with the mechanical properties of the material,looking for the reason of the flange crack and Invalidation.