Patent ID: 11931920
Assignee: HALLIBURTON ENERGY SERVICES, INC.
Field: Control (Instruments)
Classification: CPC B  G  E | IPC B  E

Claim 10:
11. A method of monitoring a flow rate of a liquid additive pumped to a mixing tank, comprising:
measuring the flow rate of the liquid additive pumped to the mixing tank with a flow meter;
transmitting the measurements of the flow rate of the liquid additive pumped to the mixing tank to a controller; and
transmitting, from a variable frequency drive (VFD), measurements of a rotational speed of a motor to the controller, wherein the VFD is coupled to the motor and the motor drives a pump which pumps the liquid additive to the mixing tank; wherein:
when the measurements of the flow rate of the liquid additive from the flow meter are non-zero:
utilizing the measurements transmitted to the controller from the flow meter as feedback to compare against a designated set point;
calculating an error between the feedback and the designated set point to calculate an updated output; and
transmitting the updated output to the VFD to change the flow rate of the liquid additive; and

when the measurements of the flow rate of the liquid additive are not non-zero:
transmitting measurements from a weight scale to the controller, wherein the weight scale measures a weight of the liquid additive in a storage tank;
determining whether the flow rate of the liquid additive pumped to the mixing tank is a non-zero rate based on the rotational speed measurements, and the weight scale measurements, wherein all of the measurements are made at a same time;
utilizing the measurements transmitted to the controller as feedback to compare against a designated set point;
calculating an error between the feedback and the designated set point to calculate an updated output; and
transmitting the updated output to the VFD to change the flow rate of the liquid additive.