I have add a new mesh object to create a new particle system for it to be used as a smoke flow. To emit fire, you can always use a typical "No physics" particle system. It allows fire to have some random initial velocity causing some cool turbulence and random movement.
In Particle system i have taken 10000 number of particles and particle display is point. I have use cube as a domain object and division 40. I have also use the Smoke High Resolution option for realistic effect. Also note when simulating fire that domain resolution changes fire behavior and looks. I used 2 resolution divisions for final render, but you should run some test simulations before even enabling high resolution. This way you don't have to use so much time in resimulating if some values are messed up.
Smoke in Particles:
Now create the smoke "Flow" using this particle system. As for the settings: I have used "Temp. Diff" to 1.0 to get faster rising fire. You can lift it even higher if you want it to rise even faster, lower it if you want "slow motion". This also depends on how large fire are you making.
Material settings for Domain :
Next the settings of the two Voxel Data textures used to create the fire effect from the Blender smoke simulation. The first one has the usual settings to set the density of the volume material accourding to the voxel data of the simulation. The second one has the most important part of the setup - the color ramp that multiplies on the emission color. Notice it's got completely transparent parts on both ends and no part is fully opaque. After baking particles you can see the final render output in video.