 The pressure jet
atomizer utilizes the supply pressure energy to atomize the fuel into a spray
of finely dispersed droplets. Provided adequate fuel pressure is used,
extremely good combustion results can be achieved.
The fuel oil is fed into the swirl chamber by means of the tangential ports in
the main atomizer body. An air core is set up due to the vortex formed in the
swirl chamber; this results in the fuel leaving the final orifice as a thin
annular film. This film of fuel has angular as well as axial velocity causing
the fuel to develop into a hollow con as it discharges from the orifice.
This type of atomizer has a poor turn down ratio. A small drop in atomizing
pressure will result in a dramatic reduction in combustion performance. Two or
three nozzles are sometimes fitted to achieve turn down, one in use on low
fire, two on medium fire and three for full rate firing. A variation of the
pressure jet atomizer is spill return or recirculating burner. The problems
with this type of burner are that the atomizer has an increasing cone angle of
the issuing spray as the burner is turned down with impingement on the furnace
walls, being made possible and the additional problem of how to dispose of the
returned hot oil if the burner has been running for prolonged periods on low
fire.
Danfoss™ pressure jet atomizer
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