Abstract: A method for operating a pump includes 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; for each first system parameter value (P10), 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 a control valve that controls fluid flow through a return line connecting the suction and discharge sides of the pump so that the monitored second system parameter value (P2m) does not fall below the minimum allowable second system parameter value (P20).

Abstract: Protecting a hydrocarbon pump from excessive flow rates in a hydrocarbon fluid system comprising an electrical motor for driving the pump. For each of a plurality of gas volume fraction values of the hydrocarbon fluid, establishing a maximum torque limit for the pump by mapping the maximum allowable torque of the pump as a function of the differential pressure, thereby creating a plurality of maximum torque curves, each representing the maximum torque limit for a unique gas volume fraction value. Establishing a master maximum torque curve which represents the maximum torque limit for all gas volume fraction values. Monitoring the torque of the pump and the differential pressure across the pump. Based on the monitored differential pressure and using the master maximum torque curve, establishing a maximum allowable torque for the pump. Taking action if the monitored torque exceeds the established maximum allowable torque.

Abstract: A method of sharing load between a plurality of parallel fluid pumps in a subsea fluid pumping system having first and second pumping units, each of which includes a respective first and second pump, the method including establishing a pump limit characteristics diagram for the first pumping unit by mapping a minimal allowable torque of the first pumping unit as a function of a differential pressure across the first pump, identifying a permissible operating region of the first pumping unit defined by a set of minimum allowable torque values for the first pumping unit, establishing a pump limit characteristics diagram for the second pumping unit by mapping a minimal allowable torque of the second pumping unit as a function of a differential pressure across the second pump, identifying a permissible operating region of the second pumping unit defined by a set of minimum allowable torque values for the second pumping unit, monitoring the torque of the first pumping unit and the differential pressure across the f

Abstract: A method of operating a system (16) for pumping a fluid, which system comprises: a pump (17) for pumping the fluid; and a variable speed motor (20) for driving the pump (17). The method comprises the steps of: identifying a first system parameter (PI); identifying a second system parameter (P2) which is a function of the torque of the pump; setting a target value (P10) for a first system parameter; monitoring the first system parameter (PI); establishing a target value (P20) for the second system parameter based on the difference between the target value and the measured value of the first system parameter; monitoring the second system parameter; and regulating the rotational speed of the pump such that the difference between the monitored value and the target value of the second system parameter is minimized. A system for implementing the method is also disclosed.

Abstract: A method of sharing load between a plurality of parallel fluid pumps in a subsea fluid pumping system (1) comprising a first fluid pumping unit (2a) comprising a first pump (3a) and a first motor (8a) which is drivingly connected to the first pump, which first pump comprises a suction conduit (4a) which is in fluid communication with a fluid inlet conduit (5), and a discharge conduit (6a) which is in fluid communication with a fluid outlet conduit (7); a second fluid pump unit (2b) comprising a second pump (3b) and a second motor (8b) which is drivingly connected to the second pump (3b), which second pump comprises a suction conduit (4b) which is in fluid communication with the fluid inlet conduit, and a discharge conduit (6b) which is in fluid communication with the fluid outlet conduit, thus rendering the second pumping unit parallel to the first pumping unit; a return conduit (9) providing a feed-back path for the fluid from the outlet conduit to the inlet conduit; and a control valve (10) controlling the

Abstract: A method of protecting a hydrocarbon pump (6) from excessive flow rates in a system for pumping a hydrocarbon fluid, which system comprises said pump and an electrical motor (10) for driving the pump.

Abstract: A system (16) for pumping a fluid, comprising: a pump (17) comprising a suction side (18) and a discharge side (19); a motor (20) for driving the pump, which motor is drivingly connected to the pump via a shaft (21); a return line (23) providing a feed-back conduit for the fluid from the discharge side to the suction side; a control valve (24) controlling the flow of the fluid through the return line; and a first sensor device (27) for monitoring a first system parameter which is a function of the differential pressure across the pump.

Abstract: A method of operating a system (16) for pumping a fluid, which system comprises: a pump (17) for pumping the fluid; and a variable speed motor (20) for driving the pump (17). The method comprises the steps of: identifying a first system parameter (PI); identifying a second system parameter (P2) which is a function of the torque of the pump; setting a target value (P10) for a first system parameter; monitoring the first system parameter (PI); establishing a target value (P2o) for the second system parameter based on the difference between the target value and the measured value of the first system parameter; monitoring the second system parameter; and regulating the rotational speed of the pump such that the difference between the monitored value and the target value of the second system parameter is minimised. A system for implementing the method is also disclosed.