| 摘要 |
575,585. Gas-heating furnaces. AKT.-GES. FUR TECHNISCHE STUDIEN. March 28, 1944, Nos. 5700 and 5701. Convention dates, March 29, 1943, and Nov. 26, 1943. [Classes 64 (i) and 64 (iii)] In a gas heater with heater elements arranged close to the internal surface of its combustion chamber, tubes 25, 26, Fig. 7, project into the combustion chamber 20 from at least one distributing header 23 and one collecting header 24 arranged above that chamber, and a plurality of small tubes 27 exposed to the heat from the fire in the heater connects each tube 25 connected to the first header 23 to one of the tubes 26 connected to the second header 24, to form a heater element. The tubes 27 may be omitted near the flue outlet. Those parts of the tubes 25, 26 that are without small tubes may be of smaller diameter than elsewhere. The tubes 25, 26 may decrease in diameter downwardly, either continuously or in steps, and the diameters of the tubes 27 may decrease correspondingly. The lower ends of the tubes 25, 26 may be joined by narrow U-shaped tubes 28 which may be accommodated in recesses 29 in a fireproof wall 22. The two arms of the tubes 28 may be connected by small tubes spaced further apart than on the tubes 25, 26. The tubes 25, 26 may be parallel or, as shown, convergent, and the tubes 26 may be of smaller diameter than the tubes 25. The ends of the small tubes opening into the tubes 26 may be flared. The small tubes are bent and arranged to protect the larger tubes from radiant heat. For example, the tubes connecting the tubes 14, 15, Fig. 5, may be bent as shown at 17<1>-17<4>, the U-bends being supported by the arms 17<1>. The distances between the small tubes may be less where the radiation is high than where it is lower. In the form shown in Fig. 10, the larger tubes 40, 41 are also protected by insulating material 44 inserted in the spaces between the small tubes 42<1>-42<3>, which are bent so that the ends of successive tubes join the tubes 40, 41 at point 120‹ apart in plan.
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