Anybody know of one? Or have an alternate solution?


You may want to consider a "Temperature Alarm" in lieu of a smoke detector. It is the typical approach in dusty industrial conditions. Be sure it is one with a "Rate of Rise" capability vs just an absolute temperature set point.

May be a little more expensive than a smoke detector but should be able to get one for under $100. Usually have to also create the actual alarm because they are just a sensor and you need to then trigger some event like ring a bell, call the fire dept, etc. But you may find an integrated model.

Maybe Grainger? Not sure.