Pang -
All you need to produce a non-luminous flame is some way to get a
lot of oxygen to the flame. You can also do it by burning up a compound
that doesn't need as much oxygen to burn. Examples of things that can
produce non-luminous flames include the bunsen burners that you
mentioned (which generally burn methane) and acetylene torches. The
torches that the olympic runners carry are also sometimes non-luminous.
Examples of luminous flames are the more familiar ones - burning wood,
candles, etc. The flame of the actual Olympic cauldron is also
typically luminous.
-Tamara
(published on 10/22/2007)