What is process control?
5 April 2024
Process control is a system of mechanisms, devices and software designed to maintain and regulate the behaviour of a particular process or system. It is a crucial concept in various industries, including manufacturing, chemical engineering, petrochemicals and many others. The primary goal of process control is to ensure that a process operates efficiently, safely and within specified operating conditions to produce consistent and high-quality results.
Key components and concepts of process control include:
Sensors
These devices monitor various process variables such as temperature, pressure, flow rate, level and more. Sensors provide real-time data about the state of the process.
Actuators
Actuators are mechanisms or devices that make adjustments to the process based on the information received from sensors. They can include valves, motors, or other control elements.
Controller
The controller is the central intelligence of the process control system. It receives data from the sensors, processes that data and sends commands to the actuators to maintain or adjust the process variables as needed. There are different types of controllers, including proportional-integral-derivative (PID) controllers, among others.
Setpoints
Setpoints are the desired values for the process variables. The controller compares the actual process variables with the setpoints and makes adjustments to bring them in line with the desired values.
Feedback Control
Feedback control is a common approach in process control, where the system continuously monitors and adjusts itself based on feedback from the process. The controller makes real-time corrections to maintain the process within desired parameters.
Feedforward Control
In some cases, process control systems use feedforward control, which anticipates disturbances or changes in the process and makes adjustments before the variables deviate from the setpoints.
Safety and Alarm Systems
Process control often includes safety mechanisms and alarm systems to ensure that the process remains within safe operating conditions. If a critical parameter approaches a dangerous level, alarms are triggered to alert operators.
Open-Loop and Closed-Loop Control
Open-loop control involves setting a predetermined sequence of actions without continuous feedback. Closed-loop control, on the other hand, uses feedback from sensors to make real-time adjustments, which is generally more precise and stable.
Process control systems are used in a wide range of applications, from controlling the temperature in an oven to managing the complex operations of a chemical plant. The goal is to optimise the process for factors like efficiency, product quality and safety, while minimising waste and resource consumption.
