GB836374A - Furnace and heat exchanger for heating gas - Google Patents

Abstract

836,374. Air heating furnaces. WOODS OF COLCHESTER Ltd. Aug 29, 1958 [Aug. 30, 1957], No. 27412/57. Class 64(1) A gas heater comprises an elongated casing 11 within which is arranged a combustion chamber 44 preferably fired by an oil burner, and a heat exchanger comprising a zig-zag wall occupying the greater part of the space between the casing wall and a central baffle 16, the combustion gases passing out of the heat exchanger e.g. to an outlet connection 33, through radially extending passages 28 located in that part of the space not occupied by the zig-zag wall. In the form shown, the zig-zag wall is built of U-shaped steel sheets 14 welded together at their edges 17 the sheets together with the casing 11 and the central baffle 16 defining generally triangular passages 19 and 21 for the heating gases and gas to be heated respectively. The zig-zag wall may contact the central baffle and the casing but preferably, and as shown, is spaced from the baffle 16 by several narrow rings 18 and from the casing 11 by longitudinal extension of certain of the plates 14, e.g. as indicated at points 22. The passages 19 of the heat exchanger are closed at their ends by plates 23, 24 and heating gasses from the combustion chamber 44 are diverted into these passages by a transverse plate 25 which closes the end of the central baffle 16. After flowing through the passages 19 the heating gases pass into the space within the baffle 16 which is cut back at 27 to allow the gases to pass into the tubular passages 28. Baffles 35, 36 are provided in the passages 28 to prevent an undue proportion of the heating gases from passing direct to the flue 33. The gas to be heated flows through the passages 21 from left to right as viewed in Fig. 2 being propelled by a fan (not shown) mounted at either end of the casing 11. Regulation of temperature and output may be effected by employing a variable speed fan motor, by using a fan having blades of adjustable pitch, or by regulating the burner. A heat shield 49 may be provided around the combustion chamber. In a modification in which the shield 49 is omitted (Fig. 3, not shown), the heater is mounted in a secondary casing through which passes the gas to be heated whereby a proportion of this gas is heated in flowing over the outer surface of the casing 11.