CLOSED-LOOP CONTROL SYSTEM
Consist of the same instruments used in the open loop system but it also has a feedback sensor that monitors the controlled variable and feeds back the signal to the controller. Then the controller compares it to the set point and adjusts its output until the feedback signal equals the established set point.
The closed loop process control is more expensive and complex but the ability to maintain a constant output under changing conditions makes them a common and, in some industries, a necessary choice for a wide range of process control applications.
The closed loop process control is more expensive and complex but the ability to maintain a constant output under changing conditions makes them a common and, in some industries, a necessary choice for a wide range of process control applications.
Closed-Loop Configuration
To begin the closed -loop it has to be established the parameters for pH control. Some parameters that are being consider are the Gain , Rate Min , Rset Min, etc. Then it has to be set the required parameters for level control , like it is known in the container is measured by a level sensor that provides an analog signal to the controller, once all required parameters have been set the next step is to exit the setup mode using the lower display key and enter the setpoint for the pH control loop ; if all the required parameters are set, the controller is placed in the automatic mode by exiting the setup mode.
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- Closed-Loop Electric Diagram
This will allow the controller to monitor the pH of the batch solution in the reactor tank and control the metering pump to add reagent to the batch until the pH is neutral (7 pH) or reaches the established set point. It is important to mention that a 250 Ohm resistor has to be connected to the PID Controller in order to achieve a successful output.
Instituto Tecnológico de Estudios Superiores de Monterrey Campus Estado de México.