I've been wondering about ways of reducing carbon formation in kerosene burners. According to Lahde's book on Hydrocarbon Appliances, there were some military lanterns which used steel wool packing in the vapouriser which he suggests inhibits cracking.
Looking round the internet, there are additives now for diesel to prevent sooting. That's a bit different I guess because there is oxygen present - but I was curious if anyone had any suggestions for reducing carbon deposition.