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

Claim 20:
21. A system comprising:
a group of centrifugal pumps specified collectively for control via a single equation, each centrifugal pump in the group of a same construction and having same manufacturer net positive suction head 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, the single equation correlating NPSHr of the group with flowrate of pumped fluid based on factory acceptance tests (FAT) data of the centrifugal pumps and giving the same NPSHr for each centrifugal pump at a given flowrate of pumped fluid, wherein output of the single equation is only NPSHr,
wherein the FAT data is from factory acceptance tests performed on each individual centrifugal pump of the group, respectively, giving FAT data unique to each individual centrifugal pump, wherein the FAT data gives FAT NPSHr for each centrifugal pump of the group as a function of the flowrate of pumped fluid, wherein the FAT NPSHr of the FAT data at a given flowrate of pumped fluid varies is capable of varying among the centrifugal pumps of the group,
wherein the centrifugal pumps in the group are boiler feedwater pumps, and wherein the pumped fluid is boiler feedwater;
a control system to calculate, via the single equation, the NPSHr for each centrifugal pump in operation of the group at a respective operating flowrate of the pumped fluid and compare net positive suction head available (NPSHa) for each respective centrifugal pump in operation of the group to a sum of a net positive suction head (NPSH) margin as specified plus the NPSHr as calculated via the single equation for each respective centrifugal pump in operation of the group, wherein the control system to automatically shut down a centrifugal pump in the group in response to the NPSHa for that centrifugal pump being equal to or less than the sum,
wherein the single equation correlates select values of the FAT NPSHr of the FAT data with the flowrate of the pumped fluid, the select values comprising only maximum numerical values of the FAT NPSHr of the FAT data among the centrifugal pumps in the group at differing flowrates of the pumped fluid; and
a boiler to receive the boiler feedwater pumped by a centrifugal pump of the group of centrifugal pumps.