Numerical Simulation And Fracture Failure Analysis Of Residue Oil Pump Impeller

Based on the background of the corrosion fracture in delayed coking furnace feed pump (residue oil pump), three-dimensional mechanical model of the residue oil pump impeller with through crack was established using the large-scale finite element analysis software combined with fracture mechanics and finite element analysis of the basic theory. The stress-strain distribution of the impeller, and the stress intensity factor in the region through crack and its variation were investigated. Sampling near the fracture, the changes of the associated physico-chemical properties and the microstructure of the fracture were analyzed by scanning electron microscopy and spectroscopy to verify the reliability of the theoretical analysis. The results shown that the occurrence of intergranular corrosion brought to material damaged and extended into the micro-cracks, the fatigue of crack propagated under operating load and environmental factor’s influence, then the fast fracture taken place while the propagation to critical size. The fracture process of the impeller was first the intergranular corrosion leaded to crack initiation, then the micro-cracks tips in side A propagated to the respective direction under periodical forces, such as centrifugal force and the impeller internal media impact force, at the same time, the crack propagated to the side B until the rear cover penetrated, finally the penetrated-crack propagated to critical size and the impeller fast fractured.