Process control engineering entails the creation of electronic controllers that enable chemical processes to be automated or run with minimal human intervention. Chemical processes are multi-step systems that include reaction, purification, and final product handling. Chemical plants have been able to operate increasingly complex reactions to provide chemicals used in consumer and commercial products since the development of computer systems in the twentieth century, often with little human intervention or attention. x000D_
A simple act like opening or closing a valve can be used to control a chemical process, as well as complex control systems that react to changing conditions with a variety of responses. Because many new controllers have been programmable since the late twentieth century, this is possible. A process control engineering technician can program the controller to react differently depending on the circumstances. A change in temperature, for example, could be corrected by changing the raw material flow, or cooling water could be started on the reaction vessel.
Actual operating conditions can be compared to a normal state entered by the technician using the program in these controllers. As conditions change, the program compares them to a set of pre-programmed responses in order to correct the deviation or change. Programmable controllers are an important component of process control engineering, but they must also allow for human intervention. A remote control readout in a central control room, which is monitored by human operators, is usually used to accomplish this. x000D_
Temperatures, pressures, and flow rates are monitored using process control, which connects the controllers to a variety of sensors. Thousands of sensors may be connected to hundreds of system controllers in large chemical plants. Most systems include alarm functions, in addition to the remote control available in a central control room, to provide a visible and audible alarm. When the system conditions deviate or move away from normal by a predetermined amount, these alarms are set to give a warning condition.
In a complex process control engineering system, alarm functions can provide a wide range of warnings. A first-level alarm could be an alert that informs the control room operator that a system condition is deteriorating. In many cases, the programmable controllers will correct the problem, and plant operators will not need to do anything else.
If the controllers are unable to correct the changing condition based on their programming, a second level of alarm may be programmed, and the operator may be required to intervene. The operator can enter a different operating condition and confirm that the controller is making the correct change using buttons or dials on the controller. A visible diagram or schematic of the process, with major operating conditions and alarm points, is included in most process control engineering designs for control rooms. Rather than scanning numerous dials or gauges, an operator can quickly see where the deviation is occurring in the process. x000D_
For processes that handle hazardous chemicals, additional alarm conditions may be required. If a tank overflows or a leak occurs, sensors can be installed in strategic locations to detect the chemical release and sound an alarm. This could be a local alarm at the control room, prompting operators to take safety precautions and investigate the leak outside. Sensors may also detect leaks outside the immediate plant area, such as along the company boundary fence, in order to alert operators and others in the vicinity of the plant to a release. In a process control engineering design, the controls, sensors, and alarms are all connected and work together to manage a wide range of chemical operations.