Improvements in heat exchangers

摘要

772,685. Heating air for combustion. AIR PREHEATER CORPORATION. Jan. 10, 1955, No. 684/55. Class 64(1) Air preheating apparatus comprises two heat exchangers in series through which are passed air and gas in opposite directions, a damper controlled air by-pass for one heat exchanger and a damper-controlled duct through which air can be recirculated. Air is drawn in through the duct 12 to pass through the two heat exchangers 10 and 11 and into a combustion chamber through the divided duct 21. An air by-pass duct 25 for the exchanger 11 is controlled by a damper 28 which is responsive through a motor device 29 to the final temperature of the outgoing gas through the duct 30. Connected to the part of the divided duct 21 which is not fed by the air by-pass is a duct 20 also controlled by a damper 20a operated by a device 20b responsive to the temperature of the air entering the exchanger 10 for recirculating hot air. Hot combustion gas enters the exchanger 11 through a duct 13 and then passes through an electrostatic precipitator 15 for removal of dust particles and through the second heat exchanger 10.