| 摘要 |
729,793. Heating air for combustion. FOSTER WHEELER, Ltd. Feb. 2, 1953 [May 29, 1952], No. 2932/53. Class 64 (1). In a heat-exchanger in which heat is exchanged between two fluids through a thermal conducting wall, the hot fluid flows in two streams and the cold fluid in a single stream, first in the same general direction as one of the hot streams and then countercurrent to the other. In the form shown hot gases from a combustion chamber 15 pass to a flue 20 and thereafter divide into two streams, one stream passing through the tubes of a heat-exchange section 30 comprising series-connected tube groups, and the other stream passing through the tubes of a heat-exchange section 31. The two streams of cooled gas are reunited at the stack 37. Cold air for combustion in the furnace chamber 15, is blown by a fan 28 over the tubes of heat-exchange section 30 in the same general direction as the gas flow through the tube groups, and thereby receives heat. The heated air is then directed countercurrent to the gas stream, over the tubes of heat-exchange section 31 where it receives further heat before passing through duct 17 leading to burners 16. This arrangement it is stated, reduces the risk of corrosion in the air heater by condensation from the cooled flue gases. The gas flow through the respective sections 30, 31 may be controlled by dampers 43, 44. The streams of heating fluid may come from separate sources and may leave the apparatus from separate outlets. The air to be heated may flow through the tubes and the other heating gas over the tubes. |
