Patent GB-741440-A (GB)
Title: Improvements relating to liquid fuel burners
IPC: F23D11/28
Filed: 1953-04-24
Abstract: 741,440. Spray burners. BABCOCK & WILCOX, Ltd. April 24, 1953 [April 25, 1952], No. 11407/53. Class 75(1). A wide range return flow mechanical atomizing burner has an atomizer head 48 arranged to direct fuel from a position outside a furnace chamber through a port 10 formed in the furnace wall 11, the fuel being discharged from a whirl chamber as a spray cone, a bladed impeller 50 between the outer periphery of which and the port 10 is an annular air flow space and auxiliary air discharge means adapted by directing air through an annular zone adjacent the atomizer head and against the rear of the spray cone to collapse the spray cone sufficiently to prevent impingement, over a lower part of the load range, of fuel particles on the port 10. The atomizer head 49 is constructed as described in Specification 696,072 and is secured to the end of. a burner barrel disposed inside a distance piece 47 extending through a cover plate 41 closing an opening in an outer wall 18 spaced from the furnace wall 11. A sleeve 65, Fig. 2, is screwed on to the inner end of the distance piece 47 and forms with the distance piece an annular air chamber 75 supplied with air at low pressure through nipples 67, 67<SP>1</SP> connected by pipes 73, 731, Fig. 1, to a coupling 71 extending through the cover plate 41. The inner end of the sleeve 65 has an inwardly directed flange 68 which tightly engages the distance piece 47 and which is provided with apertures 80 through which the air discharges parallel to the axis of the burner head against the spray cone. The impeller 50 is secured to an outwardly directed flange 69 on the sleeve 65 and comprises a series of openings and associated deflector blades. The furnace port 10 is defined by a conical metal ring 20 secured to the metal casing 12 of the furnace wall. A further conical metal ring 20 is supported within the ring 20 by studs 16, the space between the rings forming a narrowing passage for secondary air and the space within the inner ring forming a passage for primary air. Air swirling vanes 60, 70 are provided on the inner surfaces of the rings. The primary and secondary air is delivered by a fan to a passage 19 between the outer wall 18 and the furnace wall 11 and the flow of air is controlled by segmental blades 55 pivotally mounted between the distance piece 47 and a ring 45 secured to a spool 15 secured to the outer metal ring 20. The blades are rotated by pinions 54 engaging a gear 56 on a sleeve 57 surrounding the distance piece 47 and connected to operating mechanism as shown in Specification 509,252. In an alternative construction shown in Fig. 6 for supplying the auxiliary air adjacent to the atomizer head an annular air chamber 90 is formed between an inner sleeve 82 spaced from the burner barrel 81 by a ring 83 and an outer sleeve 88. The furnace end of the inner sleeve is threaded to receive an extension 86 on an annular plate 85 formed with air discharge ports 87 and a cap 91, which may support the impeller is screwed on to the furnace end of the outer sleeve and has a lip 92 clamping the port plate 85 to the outer sleeve. A gland 94 is screwed on to the outer end of the outer sleeve and compresses a packing ring 96 against a ring 93 welded to the inner sleeve. An annular flange 97 on the gland fits closely over the burner barrel 81. Air is delivered to the chamber 90 by at least one nipple 99 secured in a port in the outer sleeve. In this construction the chamber assembly is longitudinally adjustable on the burner barrel.