What is a Babington?

The Babington burner works in principle the same way as a whale's blow hole. Some people think that when they see a whale breath that there is steam coming from its blow hole. But that is not the case. When it exhales it is blowing air through its blow hole. This hole is covered  by a thin layer of water that is flowing over its head. The air that the whale is blowing out its hole is piercing this water, and the water is atomised. So what you see is just a very fine mist of water.

The Babington burner is working in the same way.  The fuel (waste motor, or waste vegetable oil) is pumped over a curved shape (a steel or copper ball, outside of a steel pipe or even the back of a spoon) and creates a thin film of fuel over the surface of the shape due to the surface tension.  To make sure that the waste motor or waste vegetable oil is thin enough to atomise, the waste oil is pre heated to 80 degree Celsius. When this film is pierced by a jet of air from a very small hole (0 .010 inch), the fuel will be atomized into a very fine mist, and also there is enough air mixed in to make a very combustible fuel  mix.

Most of the time there's no further need for a additional ventilator or fan to mix in extra air to accomplish compete combustion.

The very BIG advantage of a waste oil Babington burner is that there's no nozzle that can clog up. Because the fuel flows over the small air hole, rather than going through it, there is very little chance that the hole will get blocked. As long as the fuel pump can handle the con terminations that are in the fuel ( metal particles, pieces of French Frye's, or even dirt), and there is enough air pressure at the nozzle the burner will keep working.
There is one (small) drawback however. Because the fuel is flowing over the ball you need a catch the fuel that is not atomised. A can or sump underneath the ball to catch this fuel is needed.

In this design there is a return flow of oil to the sump where the oil will be pumped back to the burner.