Method and apparatus for liquid feed dispersion in fluid catalytic

Abstract

An improved liquid hydrocarbon feed method is disclosed wherein substantially all of the liquid is converted to mist sized particles over a wide angled dispersion pattern without a concurrent shroud of steam or water. Such dispersion promotes vapor phase catalytic reaction between hydrocarbon vapors and fluidized catalyst in a reaction time of 1 to 3 seconds. The misting nozzle is characterized by a swirl chamber to which the full hydrocarbon feed, with or without steam included in the feed, is supplied for centrifugal rotation by vane members to form a free vortex. The flow is then released through a reduced area square-edge orifice having a short throat to form and maintain a characteristic 'vena contrata' from such an orifice during flow into the catalyst stream in the riser reactor for dispersion over a wide angled conical dispersion pattern. Such flow from the orifice allows the nozzle to be recessed out of the flowing catalyst stream. This keeps the nozzle cooler and minimizes mechanical erosion of the nozzle by the flowing, heated catalyst, without use of two phase nozzles to separately add steam or water. However, if desired steam may be used as a portion of the single fluid flow from the nozzle to reduce partial pressure of the vaporizing hydrocarbon feed. In a preferred form, the liquid feed is introduced into the transition section of a riser reactor.