Patent GB-756127-A (GB)
Title: Improvements relating to burners with mechanical atomisation, for heating industrialfurnaces
IPC: F23D11/00
Filed: 1954-10-07
Abstract: 756,127. Supplying fuel to spray burners. FLEURY, A. Oct. 7, 1954 [Nov. 4, 1953], No. 28927/54. Class 75(1). [Also in Group XXIX] A burner in which fuel is mechanically atomized comprises two jets 13 of different capacities adapted to be automatically and separately projected into or both withdrawn from an operative position in a burner sleeve 1, an electro-magnetically operated rotary distributing valve 7 having an inlet 57 for the fuel, two outlets 39, 40 feeding the jets alternately and a by-pass 41 for the jet not in use, and a device, such as a pyrometer 29 or a thermostat, associated with the rotary valve for controlling the two different rates of burning. Each jet 13 is mounted on the end of an elbow pipe 14 extending through an inclined slot 18 in a plate 17 adjustably secured to the burner sleeve 1. The other end of each elbow pipe is secured to a piston 15, Fig. 4, in a cylinder 16 connected by a pipe 20 to one of the outlets 39, 40 of the rotary valve 7. The fuel pressure acting on the piston pushes the elbow pipe to the top of the slot 18 against the action of springs 23 and thereby carries the jet through an aperture 21 in the burner sleeve 1 to the centre of the sleeve. Each piston has an axial bore for conveying the fuel to the jet and a non-return valve 19 is fitted in each bore. The rotary valve 7, comprises a body 35, a rotary element 36, a cover 37 and a plate 38. The fuel is delivered from a pump 5 through a heater 6 to the inlet 57 in the plate 38 and passes to an annular passage 52 in the cover 37 registering with a circle of eight equally spaced holes 44 through the rotary element 36. The outlets 39, 40 from the rotary valve to the pipes 20 leading to the jets 13 consist of two ports in the body 35 located so that when one port registers with one of the eight holes 44 in the rotary element 36 the other registers with the end of one of eight ducts 46, Fig. 8, formed on the undersurface of the rotary element and communicating with an annular duct 45 in the rotary element in constant communication with the by pass 41 which comprises a further port in the body 35 incorporating a non-return valve 43 and connected by a pipe 42 to the fuel tank 2. The rotary element is rotated in steps of one sixteenth of a revolution by a ratchet and pawl mechanism operated by a spring-returned lever 49 actuated by an electromagnet 47 energized through the hot or cold contacts H, C of the pyrometer 29 or thermostat and through a change over switch 30.. The latter is actuated by a piston 62, Fig. 7, within a cylinder 59 mounted on the top of the rotary valve and connected at one end by a bore 53 in the plate, cover and body of the rotary valve 7 to the fuel outlet port 39 and at the other end by a bore 60 in the plate to a spiral channel 61 cut in the cover 37 and communicating through bores 55, 54 in the cover with the other fuel outlet port 40. To start the burner a push button 24, Fig. 1, is depressed to energize a contactor 25 which closes the circuits to a spark igniter 9 and to a motor 3 driving a centrifugal blower 4 and the fuel pump 5. The fuel is discharged from the high capacity jet and the flame energizes a photo-electric cell 8 which operates a relay 27 to open contacts 26 to de-energize the igniter 9 and to close contacts 28 shunting the push button 24 which can therefore be released. When a predetermined temperature is attained the pyrometer closes the contact H to energize the electro-magnet 47 through the change-over switch 30 and consequently the rotary element 36 of the valve 7 is moved by one step to direct the fuel to the low capacity jet and to connect the high capacity jet to the fuel tank, the low capacity jet automatically replacing the high capacity jet at the centre of the burner sleeve. At the same time the piston 62 moves slowly from one end of the cylinder 59 to the other and at the end of its movement actuates the changeover switch 30 to connect the electromagnet to the cold contact C of the pyrometer and thus de-energize the electro-magnet. At change-over from one jet to the other the photo-electric cell 8 closes the contacts 26 to the igniter 9 and opens the contacts 28 to the motor 3 but to keep the motor running a switch 31 shunting the contacts 28 is closed when the electro-magnet 47 is energized. If the burner supplies too much heat at its low combustion rate the pyrometer energizes a relay 33 through a contact 32 to close down the motor. The air intake to the blower 4 is controlled by a valve 11 operated by a piston 12 in a cylinder connected at each end to the fuel supply pipes 20 to the jets. In order to withdraw both jets from the burner sleeve when the motor is stopped, a valve 65 is included in the fuel supply sustem and comprises a barrel 66, Fig. 11, communicating by ports 68, 69 with the by-pass pipe 42 connected to the fuel tank and by ports 70, 71 with a pipe 571 connected to the fuel inlet 57 of the rotary valve 7 and by a port 67 with the fuel heater 6. A piston 72 having two grooves 73, 74 slides in the barrel and has a bore 75 extending from one end to a cross passage 76 in the groove 73 and a reduced bore 77 extending from the cross passage to the other end. When the motor is stopped a spring 78 urges the piston into the position shown in which the ports 70, 71 are connected by the groove 74 to the ports 68, 69 so that the fuel in the jet in use drains away to the fuel tank. When the motor is again started the fuel pressure moves the piston against the action of the spring to a position in which the other groove 73 connects the ports 70, 71 through the cross passage 76 and the bore 75 to the port 67 and a pin 80 closes the end of the reduced bore 77.