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Minimum recirculation flame control (MRFC) pulverized solid fuel nozzle tip

  • US 6,089,171 A
  • Filed: 08/15/1997
  • Issued: 07/18/2000
  • Est. Priority Date: 07/08/1996
  • Status: Expired due to Term
First Claim
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1. A minimum recirculation flame control solid fuel nozzle tip for use in cooperative association with a pulverized solid fuel nozzle of a firing system of a pulverized solid fuel-fired furnace:

  • a. a secondary air shroud mountable in supported relation to and at one end of the pulverized solid fuel nozzle, said secondary air shroud having an inlet end and an outlet end, said secondary air shroud including a bulbous configuration at the inlet end of the secondary air shroud, said bulbous configuration being operative to minimize any bypassing of secondary air around said secondary air shroud when said secondary air shroud is in a tilted condition and and also being operative to enhance a cooling effect produced by the flow of secondary air through said secondary air shroud, said secondary air shroud also including rounded corners, said rounded corners being operative to produce higher velocities in said rounded corners of said secondary air shroud to thereby minimize low velocity regions on said secondary air shroud whereat solid fuel deposition could occur;

    b. a primary air shroud mounted in supported relation within said secondary air shroud, said primary air shroud including a leading edge and a trailing edge, said trailing edge of said primary air shroud being recessed from said outlet end by an amount sufficient to remove said trailing edge of said primary air shroud as a potential surface for solid fuel particles, said primary air shroud also including rounded corners, said rounded corners of said primary air shroud being operative to increase velocities in said rounded corners of said primary air shroud thereby assisting in helping to avoid deposition of solid fuel particles at the rounded corners of the primary air shroud and if such deposition does occur assisting in effecting removal of such solid fuel particles;

    c. a secondary air shroud support interposed between said secondary air shroud and said primary air shroud so as to be operative for effectuating support of said secondary air shroud relative to said primary air shroud, said secondary air shroud support being recessed from said trailing edge of said primary air shroud by an amount sufficient to keep a recirculation region and vertical deposition surface created by said secondary air shroud support away from said outlet end of said secondary air shroud so as to thereby reduce influence of said secondary air shroud support on the deposition and also sufficient to allow said outlet end of said secondary air shroud and said trailing edge of said primary air shroud to independently expand relative to one another thereby reducing thermally induces stress in the secondary air shroud and the primary air shroud; and

    d. a splitter plate supported in mounted relation to and within said primary air shroud, said splitter plate being recessed from said outlet end of said secondary air shroud by an amount sufficient to remove said splitter plate as a site susceptible to potential deposition of solid fuel particles and sufficient to provide some cooling of said splitter plate by virtue of shielding provided to the splitter plate by said secondary air shroud.

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