#1 Fan on #2 Cooler tripped, while resetting the fan, a process upset condition occurred allowing hot clinker to exit the #2 Cooler. This hot clinker exceeded the temperature rating for the belt. This created a chain reaction where #1 Clinker Belt, then #2 Clinker belt both caught fire. When #2 Clinker failed, it fell onto the Indine Fuel Transfer Belt, igniting it