| 摘要 |
The delivery duct (2) of a blower (1) communicates with heat exchangers (10, 20, 30) located in series relationship within a stack conveying flue gases arriving e.g. from a boiler. Air is introduced into the blower from pivot and second ducts (40, 41), the second duct introducing ambient air preheated in an inner tube of heat exchanger (30). The amount of air entering the blower from the two ducts is controlled by distributing valve means (51) driven by a temperature sensor located in the coolest zone of the stack. The air passes through the heat exchangers (10, 20, 30) and exits through outlet duct (60) to the utilising apparatus. Further valve means (62) controls the amount of air passing to the outlet duct to be mixed with ambient air preheated in the inner tube of heat exchanger (30). <IMAGE> |
