Patent ID: 11920603
Assignee: nan
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A method of operating a system for pumping a fluid, the system including a pump comprising a suction side and a discharge side, a motor for driving the pump, the motor being drivingly connected to the pump via a shaft, a return line providing a feed-back conduit for the fluid from the discharge side to the suction side, and a control valve for controlling the flow of the fluid through the return line, the method comprising:
establishing a pump limit characteristics diagram by mapping a first system parameter (P1) as a function of a second system parameter (P2) to identify a permissible operating region of the pump, wherein the first system parameter (P1) is a function of a differential pressure across the pump and the second system parameter (P2) is a function of a pump torque;
for each first system parameter value, identifying a minimum allowable second system parameter value (P20);
monitoring the first system parameter (P1) and identifying a minimum allowable second system parameter value (P20) corresponding to the monitored first system parameter value (P1m);
monitoring the second system parameter (P2) and comparing the monitored second system parameter value (P2m) with the identified minimum allowable second system parameter value (P20); and
regulating the control valve based on a relationship between the monitored second system parameter value (P2m) and the minimum allowable second system parameter value (P20) such that the monitored second system parameter value (P2m) does not fall below the minimum allowable second system parameter value (P20);
wherein the system comprises a variable speed drive for operating the motor, and wherein the step of monitoring the second system parameter (P2) comprises sampling the second system parameter (P2) from the variable speed drive;
wherein the step of identifying a minimum allowable second system parameter value (P20) comprises compensating the minimum allowable second system parameter value (P20) for at least one of mechanical losses in at least one of the motor and the pump and electrical losses between the variable speed drive and the motor; and
wherein said mechanical losses are determined based on a rotational speed of the pump and said electrical losses are determined based on a power of the pump and the rotational speed of the pump.