Fmc Kongsberg Subsea As

Karen Todal

Helge Grøtterud

A method of operating a system () for pumping a fluid, which system comprises a pump () comprising a suction side () and a discharge side (); a motor () for driving the pump, which motor is drivingly connected to the pump via a shaft; a recirculation conduit () providing a fluid path for the fluid from the discharge side to the suction side of the pump; and a control valve controlling the flow of the fluid through the recirculation conduit, which method comprises the steps of: mapping a plurality of minimum torque diagrams for the pump, where each minimum torque diagram identifies the minimum allowable torque of the pump as a function of an operational parameter of the pump, e.g. the differential pressure over the pump; from said plurality of minimum torque diagrams, identifying the minimum torque diagram best representing the current operation of the pump; monitoring said operational parameter of the pump and, from the minimum torque diagram best representing the current operation of the pump, identifying a minimum allowable torque value corresponding to a monitored value of said operational parameter of the pump, e.g. a monitored differential pressure value; monitoring the torque of the pump and comparing a monitored torque value with the identified minimum allowable torque value; and regulating the control valve such that the monitored torque value does not fall below the minimum allowable torque value. A corresponding pumping system is also disclosed.

System for pumping a fluid and method for its operation

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.

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Haslum, Norway

Karen Todal