Burner Control and PID


Thread Starter


Does anyone have an example of Control Logic for a burner with constant material flow. Material (rock and sand) vails through the flame to dry. My problem is when the PID reaches setpoint my flame shuts down. I need to maintain a flame to dry the material and keep the output temp constant. Thanks in advance!
I assume that your problem is that when the process temp = setpoint the PID output drops to zero, causing the burner control to shut until the burner cuts off. Two ideas:

1) figure out how to set a minimum output on the PID to maintain a low stable flame. Don't know your platform but this may be accomplished in the PID configuration, or by verifying the PID output register is at least a minimum value following the PID computation (if output less than xmin, set output equal to xmin). Hopefully the low stable flame does not cause temp to rise out of control.

2) mechanically tweak the burner control valve so that it doesn't shut completely (most burner controls use separate gate and backup gate valves for system shutdown)
Dear Randy,

In typical burner management systems we always use PI control and use little biase to keep burner running at low fire. This will help to control your typical application.

Please provide information of your PLC I will write programme for this application and send you.

Irfan Ashiq

Retired. Instrument Engineer

Alejandro Sanchez

To solve your problem find:

1.-Burner turndown range, that is the ratio of maximum to minimum fire, and see if your burner can stay on at minimum fire. If burner cannot stay lit you might use a standing pilot.
2.-The flame relay must be able to keep both high and low flames operational, so check for good flame signal across the burner range.
3.-You must use PID control after you set your burner stable between high and low fire so that you don't have overfired and humid material due to excesive high or low fire operation. PID allows you to find a mid fire position to suit your operation.
4.-If you find this useful but still have problems, e.mail me the make and model of your burner, operating temp., a brief sketch of your process, and we'll try to help you.


Alejandro Sanchez
[email protected]