Switching of the set value for the control valve
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It is a manufacturing process that involves two reaction temperatures: 130 degrees and 200 degrees. The process starts with pressing a button to add material; once the container is full, the control valve adjusts the temperature to 130 degrees as set. After 30 minutes, the set value for the control valve automatically changes to 200 degrees, and the adjustment is completed after another 10 minutes. Then the material is discharged, and the process automatically enters the next cycle to add material again. What function blocks are used to implement DCS?
:Add a delay function to the lol interlock. Is your start button pulse-type? The start button should open a feeding valve, and then wait until it’s filled (there should be a signal for this); once the feeding valve closes, set the temperature to 130 degrees with a 30-minute delay, then set it to 200 degrees with a 10-minute delay. After that, open the exhaust valve, and check whether everything has been emptied via a detection signal. Then return to the start button, and repeat this process – that’s roughly the idea.
There are countless ways to achieve this functionality; SFC, ST languages – which functionality are you referring to?
The control valve is used to adjust the steam supply volume, while the jacket of the reaction vessel is used to control the temperature; is there any fluctuation when switching between the set values of 130 degrees and 200 degrees?
There are many ways to achieve this; the one I use most often is the SEL function block. Furthermore, switching the given value between 130 and 200 will cause some disturbance. The key is: what is the actual temperature when it reaches 200° (or 130°)? If the deviation is large, the control valve will definitely open or close completely.