We have been all ready to run the plant for the last few weeks since we got the permit issues resolved.
We have been having some issues with the dryer chain flail electric motors cutting out on us after a few minutes of operation. This issues started several months ago and it has been slowly getting worse over time. Initially it was just a small irritant we could just restart it and go on.
We now have it cutting out so often that we can not operate properly it cuts out every 10 minutes or less. This makes the dryer basically unusable. We have been working with several experts testing and trying to determine what the issues are.
We have tested all the components and they are testing out just fine. We also talked to ABRI and they suggested that the problem might be some part of the air flow system would be plugged so the fan is not effective and material stays in the flails too long. We searched the entire system and found a big plug in the exhaust stack that some animal had packed a nest into it that we were unaware of. I think this was due to periods of little use while waiting to get our permit issues resolved.
We tested the flails again after cleaning out the nest and the issue still exists but with much longer runs again. So now we are back to the flails running for 15 to 20 minutes. We again could run and restart when it stops. We are currently planning to try a couple of other tests to see if we can fix the problem.
The current best guess by some industrial electricians is that our frequency drives are too small. The frequency drives are control boxes that control the electric motor speed. The flail motors are 3 horsepower and the frequency drives are also for 3 horsepower.
The motors are 220-240 volt 3 phase motors. The frequency drives can convert single phase 220-240 power to 3 phase and that is what we are doing for now. This used to work but the electricians/engineers think drives were marginal in other words the 3 hp drives could only barely convert enough single phase power to 3 phase. The estimate is that these issues are coming up because there is some deterioration of the motors and frequency drives after months of use.
The electricians/engineers suggest that the standard way to do this is that the frequency drives should be sized larger than the motors if you are converting single phase to 3 phase so we are considering putting larger drives in and seeing if this solve the problem. These are pretty expensive so we have not decided to do that without substantial testing.
We are close to deciding to get the bigger drives.