Alternating magnetic field flow meters

A method of measuring a flow rate of a fluid flow by an alternating magnetic field flow meter, the method comprising:

• generating a first magnetic field to move a magnetic token along a direction of a flow path of a fluid flowing through a conduit;
• detecting a first electrical signal based on the movement of the magnetic token along the direction of the flow path;
• generating a second magnetic field to move the magnetic token opposite to the direction of the flow path;
• detecting a second electrical signal based on the movement of the magnetic token opposite to the direction of the flow path;
• and
• determining the flow rate of the fluid flow based on the detected first electrical signal and the detected second electrical signal.

An alternating magnetic field flow meter apparatus comprising:

• a magnetic token movable within a conduit configured to guide a hydrocarbon flow along a flow path;
• a magnetic field generator configured to generate alternating magnetic fields within the conduit to move the magnetic token along the flow path with a first flow velocity and opposite to the flow path with a second flow velocity;
• a detector configured to measure respective first and second electrical signals responsive to the alternating magnetic fields, the first and second electrical signals associated with the first and second flow velocities;
• and
• a processor configured to determine a flow rate of the hydrocarbon flow based on the first and second electrical signals.