Master-Slave with Slave reset by temperature

A

Thread Starter

akdeepwater

Our crude heater has a master flow controller with four slave flow controllers. The setpoint to each flow controller is biased by the output from a temperature controller. The purpose of the temperature controller is ensure that all four heater outlet flows are at the same temperature. In essense there are two PI controllers manipulating the setpoint of the slave flow controller.

The problem is the master output eventually reaches maximum (100%). There is no feedback to the master as I can't figure out how to get a common feedback from the different flow controllers.

What is the correct way to setup this control scheme?

Thanks for your help!
 
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