Study of feasibility in replacing in a centrifugal pump the static wear ring by a floating wear ring
Renner Guilherme da Costa Marques1; Hans Ingo Weber1
1 PUC-RJ
doi:10.20906/CPS/COB-2015-0501
Resumo
A major kind of pump used in refineries is overhung centrifugal pump. And some of them, which were manufactured before 80's, are still being used in refineries in Brazil. These equipments have flexible rotors since the ratio L/D is high and the packing, that offers stiffness, was replaced by mechanical seals in order to get more safety. As consequence, the dynamic response of these pumps is very sensitive to any variation of the wear ring clearance. Vibration amplitudes have been identified of more than 20mm/s rms at the bearing when the diametral clearance between static and rotational wear ring increases due to wear. And the major cause of the weariness of these components is the erosion between them and surfaces in contact. Beyond the vibration, the worn out condition of the wear ring reduces the efficiency of the pump since the flow through theselas rises. So, in order to solve these two concerns (vibration and efficiency) this study proposes to investigate the feasibility of replacing the static ring by the floating wear ring in centrifugal pumps. Floating wear ring reduces the erosion and increases the efficiency of the pump since it permits to minimize the radial clearance. In addition, because of the smaller clearance the stiffness and damping are higher, so the unbalance response becomes smaller. The disadvantage of using floating wear ring is that each one has to be designed for a specific operation condition.
Palavras-chave: centrifugal pump; vibration; floating wear ring