Patent GB-610425-A (GB)
Title: Improvements relating to high temperature recuperative funaces
IPC: F23D99/00
Filed: 1946-04-04
Abstract: 610,425. Furnaces. EVERY, C. E. (Titanium Alloy Manufacturing Co.). April 4, 1946, No. 10489. [Class 51 (ii)] A recuperative furnace for temperatures in excess of 1800‹C. comprises a pair of combustion units 20, 40 connected by a passage 60 the wall of which is of zirconium dioxide, the goods in the chamber 62 being heated by radiation from the outer surface of the passage 60, the arrangement being such that the chambers 20, 40 are alternatively used as recuperators. Air or oxygen is supplied, according to the direction of firing, through pipes 22, 42 and valves 23, 43, and the combustion products escape through the corresponding valve 45 or 25 and water-cooled chimney 46 or 26. The air passes through pieces of heated refractory material 32, 33 or 52, 53 in the spaces 21, 41, the material 32, 52 being zirconium silicate and the material 33, 53 being zirconium dioxide. The fuel gas may be passed through the refractory material, being separated from the air by a longitudinal partition, but, as shown, the fuel is admitted from a pipe 29 or 49 through a nozzle 28 or 48 of zirconium silicate into the extension 27 or 57 of the space 21, 41. The walls 34, 54 of the spaces 21, 41 are mainly of zirconium silicate, preferably of tongued and grooved blocks or bricks, sealed with zirconium silicate cement, but a lining 35, 55 of zirconium dioxide is provided in the high temperature region. The ends of the units 20, 40 are water-cooled, an outer jacket 70 having inlet and outlet pipes 71, 72 and a separate system comprising a spiral tube 73 in series with tubes 77 connecting two circular headers 76, 78 having inlet and outlet pipes 75, 79. Central plugs 38, 58 permit removal of the refractory material which is replaced through plugged openings 37. The combustion conditions may be observed through heat resistant glasses 31, 51. The passage 60 may be of tiles or cast in one piece and may be of any desired section, e.g. circular, oval, rectilinear, and the section may be uniform or non-uniform. The passage may be filled with checkerwork or suitably supported lumps of zirconium dioxide to reduce the velocity of the gases passing through the tube, and a number of liquid or gaseous fuel nozzles may be disposed around the spaces 21, 41 The fuel may be preheated, in an auxiliary unit, similar to the air heating unit described above, or, alternatively, air could be introduced through the nozzles 28, 48 and fuel through the pipes 22, 42. By modifying the disposition of the units 20, 40, the passage 60 may be disposed horizontally, or two vertical units 20, 40 may be arranged to deliver combustion products into a vertical tube with a central longitudinal partition and a closed upper end, so that the gases are constrained to a U- shaped path. The goods surround the tube and are enclosed in a removable chamber. In a further modification, the lower unit 40 of Fig. 1 is arranged horizontally to be symmetrical with the chamber 20. Alternatively, the upper unit 20 is arranged vertically and connected to the vertical tube 60 by a U-shaped bend.