Patent ID: 11965513
Assignee: SAUDI ARABIAN OIL COMPANY
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A method of operating centrifugal pumps related to net positive suction head (NPSH), the method comprising:
identifying a group of centrifugal pumps in a system, each centrifugal pump in the group of a same construction and having same manufacturer NPSH required (NPSHr) as determined for the same construction, wherein the manufacturer NPSHr does not vary among the centrifugal pumps in the group at a given flowrate of pumped fluid,
wherein a manufacturer or vendor after completion of manufacture of each centrifugal pump, respectively, of the group, performs a factory acceptance test (FAT) of each individual centrifugal pump, respectively, giving FAT data unique to each individual centrifugal pump, respectively, the FAT comprising a functional test, wherein the FAT data comprises FAT NPSHr for each centrifugal pump of the group as a function of the flowrate of pumped fluid as determined via the functional test performed for each individual centrifugal pump, respectively, in the group that gave the FAT data unique for each individual centrifugal pump, respectively, wherein the FAT NPSHr is capable of deviating from the manufacturer NPSHr, wherein the FAT NPSHr is capable of varying among the centrifugal pumps in the group at a given flowrate, wherein a number of the centrifugal pumps in the group is in a range of 4 to 60;
deriving a single equation for the group utilized to calculate NPSHr of each centrifugal pump in the group, wherein output of the single equation is only NPSHr, the single equation giving the same NPSHr for each centrifugal pump at a given flowrate of pumped fluid, the single equation correlating NPSHr with the flowrate of pumped fluid and derived based on from select values of the FAT data of the group, and wherein the select values are only a maximum numerical value of FAT NPSHr among the centrifugal pumps at each given flowrate of pumped fluid;
specifying a NPSH margin for NPSH available (NPSHa) above the NPSHr as calculated via the single equation; and
shutting down a centrifugal pump in operation of the group in response to the NPSHa for that centrifugal pump being less than a sum of the NPSHr as calculated via the single equation for that centrifugal pump plus the NPSH margin as specified.