| 摘要 |
612,027. Air and gas heating furnaces. AKT.-GES. FUR TECHNISCHE STUDIEN. May 15, 1946, No. 14711. Convention date, May 28, 1945. [Class 64(i)] [Also in Group XII] In a gas heater, Fig. 1, in which the gas passes through and is heated in tubes 5 arranged in a combustion chamber 1, a portion of the flu gases is returned by a fan 13 to the combustion chamber at least at the hottest part of the latter through gaps 15, Fig. 2, between the tubes 5. The gaps may extend over the whole length of the tubes and may be provided between groups of two or more tubes or between any two adjacent tubes. The tubes may be fixed to the wall of the combustion chamber, spaced by distance pieces or attached to one another.
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