Selection, Sizing and Operation of Control Valves for Gases and Liquids

摘要

The Instrumentation, Systems, and Automation Society (ISA) defines a control valve as a "power operated device that modulates the fluid flow rate in a process control system." Process plants contain hundred, if not thousands of control loops to help a certain variable reach a desired set point. These loops consist of sensors, transmitters, and process controllers that receive information and calculate necessary action to achieve a set point upon system disturbance. The control valve is one of the most common final control elements that the process controller manages to maintain the set point. A well-sized and selected control valve will be able to keep the process variable as close as possible to the set point, making the control valve a crucial part of the process. This paper will cover the importance of proper control valve selection and sizing, liquid and gas/vapor service sizing and solutions, and types of control valves.