Application Study On New Type Double Mechanical Seal On Centrifugal Pump For Discharge High-temperature Heavy Oil

The failure reasons of contact bellow mechanical seals used in centrifugal pumps for discharge high-temperature heavy oil in Dagang Petrochemical Company were studied, and the results showed that fluid film coking, seal ring aging, end-to heat and crack etc due to end friction heat lead to frequent failure and high incidence of fire owning to hot oil leakage which cause not only material damage, but also serious potential safety problems and other issues. The leakage mechanism of the seals was analyzed and a new concept "contact and non-contact" combination of dual mechanical seal was firstly developed to solve the failure problem. Because the seals in bottom residual oil pumps in the first joint workshop of Dagang Petrochemical Company were frequently shut-down with the specific working conditions, the new type of dual mechanical seals were designed and investigated in laboratory. Finally the seals were successfully used in industry. The study will be useful for the modification and industrial application of the new developed mechanical seals.