Depending on aircraft type, the Zonal Drying™ System consists of one or more zonal dryer units installed at strategic points in the aircraft. Each unit features a slow-moving rotor impregnated with silica gel...
...which is collecting combustible lint and dust and is partially exposed to electrically heated (fairly hot) air, and which cought fire already in the past...
A zonal dryer may sit smoldering in an aircraft hours after it has been switched off.