Multi-layer fluid curtains for furnace openings.

摘要

An apparatus and method for providing a selected atmosphere at and within an opening to the interior volume of a furnace. Two or more paralleled diffusers adjacent to the furnace opening laminarly emit different fluids and provide a multi-layer fluid curtain over the opening. The curtain has a composite modified Froude number from 0.05 to 10, and a thickness at emission of at least 5% of its extent in the flow direction. Partially covering the outside of the curtain is an optional, substantially flat, outer shield with an aperture coinciding with the furnace opening, which reduces the necessary flow rates of fluids. Optional side shields around the sides of the curtain also reduce the necessary fluid flow. A preferred diffuser comprises a porous tube in a housing with an outlet directed to emit fluid across the furnace opening. The outlet is covered with a screen to disperse the fluid flow and to protect the porous tube. <IMAGE>