The left most pictures were taken in the NXT 3 kg roaster after 5 years of roasting.  The pictures on the right were taken after 1 year of roasting in a gas burning drum roaster.  The top photos show the outlets which is a good indicator of what is being sent to the chimney.  The bottom photos are from the inside of the roasters.  On the left we see the main tube which conveys the re-circulating air from the Blower to the Roasting Chamber.  On the left is the inlet of a Drum Roaster Fan.