GB1449267A - Apparatus for and a method of burning fuel - Google Patents

Abstract

1449267 Burners AQUA-CHEM Inc 20 Nov 1973 [21 Dec 1972] 53729/73 Heading F4T Combustion apparatus, e.g. for a water tube boiler, comprises a combustion zone 33 having an inlet 32, a nozzle 55 for injecting fuel into the combustion zone, the direction of fuel from said nozzle defining a downstream direction, the nozzle including a first member 56 for receiving fuel for delivery to an atomizing space, and a second member 57 surrounding the first member for receiving atomising air, the members defining the atomizing space, an air supply pipe 58 surrounding member 57, parts of the nozzle being of frusto conical form diverging outwardly, a first plurality of passages 68 formed in the nozzle and extending from space 69 each passage terminating adjacent the inner portion 77 of frusto conical surface 70 the plurality of passages being arranged to direct fuel along surface 77 so that fuel leaves the passages, moves spirally along surface 78 and in closely shaped relation thereto so as to shape the fuel into a fuel rich core stream which flows to the combustion zone surrounded by the air delivered by pipe 58. Fuel, e.g. oil, is delivered under pressure via control pipe 56 to radial passages 68, Fig. 4, to flow into an annular passage 60 for atomization by pressurized air delivered through pipe 57, the fuel/air mixture passing through swirl grooves 74, formed on the outer surface of a nozzle part 67 or on the inner surface 77 of a nozzle part 66, to flow over surface 78 of part 66 to form the fuel rich core stream 98 which is generally hyperbolically shaped adjacent the nozzle 55. A minor portion of the air delivered by a fan (22), Fig. 1 (not shown), to a plenum chamber (23) flows via a tube 86 and pipe 58 to form a tertiary air sheath 99 around the core stream, the major part of the air from the fan flowing via an adjustable damper 34, comprising apertures in a casing 40 and apertures in a rotatable member 41, and flow straightening cores 51 to flow mainly through an annular gap 95 between a combustion chamber inlet member 94 and a bafflle 36 to form an outer air sheath 100, a small air flow passing through a mesh disc 90 of the baffle and through spaced vanes 92 aligned generally tangentially to the periphery of disc 90 to prevent back-flow of the core stream 98. The stratification of the air provided by the outer air sheath 100 and tertiary air layer 99 about the core-stream 98 results in burning of the stream 98 adjacent the nozzle 55 as a fuel rich mixture substantially isolated from the sheath 100, progressive mixing of the stream 98 and sheath 100 further downstream to obtain substantially complete combustion, whereby the burning is cooler than if complete mixing and combustion had not been delayed, in particular the combustion temperature is kept below about 2500‹F thereby reducing formation of nitrogen oxides, carbon monoxide, carbonaceous particulates and unburned hydrocarbons in the exhaust gases. The damper 34 may be adjusted automatically in response to conditions in the combustion chamber 33.