There are fire tornados in the wild:
This design is based on the less dangerous (fog) tornado but without the need for a fan.
Step 1: Building the Tornado Chamber
The tornado chamber is constructed from 3 sheets of 3X5 foot Hardibacker material
Step 2: Make Tornado Chamber Walls
Cut two of the 3X5 foot sheets of Hardibacker in half to create 4 2.5X3 foot walls. The concrete sheet can be cut cleanly by scoring both sides of the sheet surface with a scoring knife. Place a 2X4 edge under the score and gently press down until the sheet bends along the score mark.
Step 3: Cut Central Hole for Stove Pipe Exhaust
Measure the center point of the 3X3 foot top of the chamber and score it with a nail. Use a compass to trace a 6.5 inch diameter hole in the center of the top sheet. Put the pen in the center and use the pointed end of the compass to score the circle (yes this is backwards, but the point scores much nicer than the pen).
Step 4: Line Drawings
The line drawings show how the walls, top and stove pipe are oriented.
Step 5: Assembly of the Chamber
Next the top is placed on the chamber
Step 6: A Warning on Running the Fire Tornado With Gasoline
Gasoline is highly flamable. Make sure there is nothing flammable around: gasoline, propane tanks, relatives or anything made from wood. The following sequence of photographs from the video show the ignition of the fuel. Note the way the flames briefly engulf the camera, even thought the spilled gas does not reach the location of the camera (this camera was on a tripod, with all people at safe distance):
The gas fumes are wafting in the air considerable distance from the liquid.