In general, it is safe to burn flammable liquids in industrial burners. However, one must keep in mind that flame front will move closer to the injection nozzle. So this may require redesign of the injectors. Also, if it is steam atomized, the fuel may vaporize in the injector, which may also cause flow rate fluctuations and flameouts.
 
Regarding the example of burning naphtha in a gas turbine, I suggest the user should check with the manufacturer.