gusterminator
Member
We have a PID loop at the plant that measures our drum outlet temp. It adjusts a damper to control the temp within the set point. We have a temperature sensor at the inlet of the drum. It isn't connected to any loop it's just there for indication. When we add feed to the drum "sawdust" the material is drawn through the drum and dried. The operators usually do a moisture sample on the material after it has went through the drum to determine what temp the SP on the PID should be at. We have a very hard time tuning this PID for the different moisture of material that is going into the drum. We receive our sawdust from many different operations and the moisture could vary as much as 30%.
We recently switched the PID to control the temp from the Inlet temp not the outlet temp. It seems to control the loop more consistent but the problem now is it takes too long for us to hit our proper moisture we need to bring the material into the plant.
The inlet temp is usually around 398F and the outlet around 72F with material going through. The closer we can keep the outlet to 72F the more consistent our moisture is.
I was wondering if a feed forward or feed back PID system would be better since we have sensors at the inlet and outlet.
I was wondering if I used two PID's one for the outlet set at 72F that when it deviates away from it's set point it tells the inlet PID to increase. So the outlet temp PID would have a stationary setpoint and the inlet PID would have be constantly changing setpoint that would control the damper.
Any suggestions is greatly appreciated.
Thanks,
We recently switched the PID to control the temp from the Inlet temp not the outlet temp. It seems to control the loop more consistent but the problem now is it takes too long for us to hit our proper moisture we need to bring the material into the plant.
The inlet temp is usually around 398F and the outlet around 72F with material going through. The closer we can keep the outlet to 72F the more consistent our moisture is.
I was wondering if a feed forward or feed back PID system would be better since we have sensors at the inlet and outlet.
I was wondering if I used two PID's one for the outlet set at 72F that when it deviates away from it's set point it tells the inlet PID to increase. So the outlet temp PID would have a stationary setpoint and the inlet PID would have be constantly changing setpoint that would control the damper.
Any suggestions is greatly appreciated.
Thanks,