Is it possible to render the fire and smoke (the same simulation), in Cycles, separately, for example as different passes?
Just do it as you normally would. Select both the domain and the smoke emitter and change their "pass index".
Or you can change their layer, and render them on a different render layer.
Save them both(Fire and Smoke) as image render. In the node editor just disconnect the nodes that create smoke so thus the ones that created emission or fire alternately... What I mean is if you want to render smoke first then disconnect emission from the mix shader, then if you want fire just disconnect the density attributes and rgb that will create smoke... If there is another way for this let me know like separating them by layers...