GB639071A - Improvements in or relating to vessels, chambers, or the like apparatus operating under pressure - Google Patents

Abstract

639,071. Mounting and lighting burners. SHELL REFINING & MARKETING CO., Ltd., JOYCE, J. R., HARRISON, W. D., WHITE, J. C. S., and TANTAM, D. H. Oct. 30, 1947, No. 29031. [Classes 75 (i) and 75 (iii)] [Also in Group XII, Apparatus for facilitating the removal and replacement of accessories without substantial loss of pressure, through the wall of a vessel maintained at sub- or super-atmospheric pressure, comprises valve or shutter means which when operated closes in a leaf-proof manner an aperture in the wall of the vessel through which an accessory is adapted to extend, sealing means adapted to effect a leak-proof seal between the accessory and the vessel when the accessory is in its operating position, and means co-operating with the accessory to prevent substantial pressure leakage while the accessory is being withdrawn to a point clear of the said valve or shutter means, the latter being arranged to close automatically before the accessory has passed the said point, or releasable means being provided for temporarily retaining the accessory of the said point while the valve or shutter means is closed. A burner tube 15, Fig. 1, passing through the wall 10 of a combustion chamber maintained at sub- or super-atmospheric pressure, may be removed without substantial change of pressure in the chamber by removing a nut 20 at the end of an enclosing sleeve 17 and withdrawing the burner until a collar 21 abuts against a spring-urged latch 25 when a gate valve 13 may then be closed by turning a lever 14. During withdrawal substantial pressure leakage is prevented by the fit of the burner in a bush 11 and of the collar 21 in the sleeve 17. After closure of the gate valve 13 the latch 25 is lifted and the burner is removed from the sleeve 17. In the apparatus shown in Fig. 2, three main burners 31 and 32, 33 (not shown), a pilot burner 34, and a spark igniter 35 are mounted in the end wall 30 of a combustion chamber, the forward ends of the burners and the igniter being surrounded by a shroud 36. Each burner is enclosed in a sleeve 37 and has rotatable thereon at its outer end a sleeve 41 having interrupted threads 42 engaging similar threads in a housing 38. The burner is released by loosening a lock nut 44 and turning the sleeve 41 by its actuating member 43 to disengage the interrupted threads, and is then withdrawn until a groove 52 reaches a latch 50. A plug valve 46 is then closed by turning a lever 47, which also rotates a sector plate 48 having a raised portion which lifts the latch 50 so that the burner cane be removed completely. The pilot burner only has a sleeve 54 in communication with a tube 55 through which air is provided to operate the burner at low load. The igniter 35 makes a sliding fit with the front part of a sleeve 56, the rear part of which receives a collar 70 carrying leaf-proof packing. When combustion has started the igniter is retracted a short distance by means of a rack 57 and pinion 58 so that the sparking electrodes 63 are well within the shroud 36 and protected from the flame. To withdraw the igniter entirely a clamp 67 is released and the igniter complete with retraction gear is withdrawn. When the electrodes 63 pass a ball 62 freely mounted in an elbow 61, the ball drops and mounts a ramp 64 to centre in the mouth of the sleeve 56 forming a gas-tight seal. A further construction is desscribed in which gate valves are mounted on sectorshaped arms pivoted on the combustion chamber wall through which the burners and an igniter tube pass and each burner tube and the igniter have collars provided with packing rings, and are withdrawn in a manner similar to that of the withdrawal of the burner shown in Fig. 1. The valve plates may each comprise a pair of members urged apart by a spring. In the Provisional Specification is described a construction in which the burner tube is moved axially into and out of the combustion chamber by the rotation of a captive nut which engages an external screw thread on the burner tube.