GB1449906A - Liquid fuel burner heads - Google Patents

Abstract

1449906 Liquid fuel burners OFR OFFICINE FRATELLI RIELLO SpA 3 Oct 1973 [6 Oct 1972] 46208/73 Heading F4T A liquid fuel burner head comprises a fuel atomising nozzle 14 and means coaxial with the nozzle to deliver combustion air around the fuel jet 'from the nozzle, said means comprising a chamber 26 with a primary air outlet 30, and a chamber 38 around the chamber 26 and having a secondary air outlet around the primary outlet 30, the secondary air outlet being adapted to deliver a secondary air flow in the form of a converging generally laminar flow that defines an inner space wherein initial combustion of the primary air/fuel mixture occurs, combustion being completed and the burning mixture diluted by circulating flow induced by the generally laminar secondary air flow outside said inner space. The secondary air outlet is defined by a continuous or interrupted annular gap between a sharp edge 48 of a portion 46 of an outer tubular member 36 and a frusto-conical surface 32, having a cone angle A of 65 to 75 degrees, on an inner tubular member 24 supported on fuel pipe 12. The surface 32 terminates in a sharp edge 34 to ensure detachment of the laminar secondary air flow. The secondary air outlet cross-section may be adjusted by a device 18, 20 acting via fuel pipe 12 to axially move member 24. The primary air outlet 30 is formed in a reduced-thickness part of a diaphragm 28 and comprises a central aperture with slots radiating therefrom and inclined to induce at least part of the primary air to flow in a vortex. Primary air flows into chamber 26 from the outlet 10 of a centrifugal blower via chamber 38 and passages 40, an adjustable nut 42 varying the proportion of primary/secondary air. The communication between chambers 38 and 26 includes a portion, e.g. between the nut and the inlets of passages 40, of smaller crosssection than outlet 30.