Flow control valves are mainly used to maintain the process flow rate in a specified range. Flow is measured and maintained either upstream or downstream of the valve.
Depending on upstream or downstream process requirement, the flow rate is measured by flow element and it send signal to controller. Controller compares the reading and gives inputs to throttle (open or close) the control valve.
Generally flow control valves are found in the inlet of separators, pump discharge line, air inlet of fired heaters, boiler water feed, reflux line of distillation columns, etc.
