Alan Smith,
If you have not already played with ultrasonic transducers or randomly moving small particles in general inside your reactors you may have not seen this effect before. In different circumstances, if your vacuum cleaner has PVC piping you might already have felt it while vaccuming certain kinds of dust. In certain cases it can cause visible static discharges. It can be a serious annoyance in wood working dust collector systems, for example:
A system similar to that of Etiam Oy (to return in-topic) or De Bellis which causes particles to rub against each other (or against other reactor components) will, if composed of materials far from each other in the triboelectric series, cause a crackle effect that may be observed and feeled outside the reactor. This alone may not necessarily be a sign of anomalous reaction, but it could be a a trigger for it.
Piezoelectric materials have a generally low "Curie temperature" above which they stop functioning. I am not aware of such a thing for tribocharging (I could be wrong).