Patent GB-779145-A (GB)
Title: Method and means for the heating of furnaces
IPC: F23D14/00
Filed: 1953-09-09
Abstract: 779,145. Gas burners. OFU OFENBAU-UNION GES. Sept. 9, 1953 [Sept. 9, 1952; May 28, 1953], No. 24975/53. Class 75(1) The invention consists in a method of and an apparatus for heating a furnace, the method consisting of altering the length of a burner flame independently of the supplies of fuel and air thereto so that the position of the maximum value of the flame temperature is displaced backwards and forwards during a heating period, the apparatus consisting of a gas burner having concentric passages to the combustion media, the passage for one medium being subdivided by a concentric separating wall and valve means enabling one of the passages formed by the separating wall to be rendered inoperative. The method can be effected with gaseous, liquid or pulverized fuels. The gas burner 4 heating the soaking-pit furnace 1 is supplied with air through a conduit 7 and with gas through a conduit 6. A flap valve 10 located in the burner casing and operated by a motor 12 controlled by a time switch 13 directs the gas into the furnace either through an inner passage 8 or through an outer passage 9 surrounding the inner passage 8. The outer wall of the outer passage 9 is corrugated at its forward end to contact the wall of the inner passage 8 to form adjacent channels for gas and air which are directed to cause whirling and hence a short flame. When the gas flows through the inner passage 8 the flame is relatively long. Secondary air may be supplied through one or more nozzles 17 mounted on the furnace wall opposite the burner and connected to the air conduit 7 by a conduit 18. Each secondary air nozzle consists of concentric passages 27, 28 alternatively connected to the conduit 18 by a flap valve 25 and the outer passage 28 contains a whirling apparatus 26. The flap valves 25 are operated by a common driving means which. may be connected to the motor 12. Flap valves 19, 20 are arranged in the air conduit 18 and in the branch of the air conduit 7 leading to the burner and are operated by the motor 12 so that when one valve is open the other is closed. The burner may be operated with an air deficiency so that the secondary air forms a second maximum temperature point in the flame and this point is displaced by the operation of the flap valve 25 of the secondary air nozzle. In another construction of gas burner the gas passes through two coaxial passages into the furnace and the flow of gas to the outer passage only is controlled by a throttle valve. Air enters around the nozzle through slots inclined to the burner axis. When the furnace is heated by a plurality of burners the position of the maximum value of the flame of each burner extends over only one part of the furnace and the regulation of the flame length in individual burners or groups of burners is effected indepently and intermittently and in a particular relative frequency. When the quantity of fuel and air is also regulated a time lag is provided between such regulation and the regulation of the flame length. The temperatures at suitable points preferably in thecentral plan of the furnace are measured by instruments and are used in manually or automatically controlling the flame length and in distributing the combustion media to the individual or groups of burners.