| 摘要 |
1,088,869. Heating air by waste gases. BABCOCK & WILCOX CO. Nov. 26, 1965 [Nov. 27, 1964], No. 50311/65. Heading F4S. In an air heater generally as described in Specification 988,353 in which a combustion air stream for a steam generator is heated as it flows serially over banks (61, 62, 63, Fig. 1) of flue tubes, the tubes extend between upper and lower tube plates and the upper tube plates 58A, 58B of the tube banks 61, 62 are carried in a common supporting structure which is cooled by air bled from the main combustion air stream. This cooling air reduces thermal stresses in the supporting structure caused by the temperature differential between the tubes of the respective banks. As shown, the supporting structure includes ducts 102, 102A for the cooling air. These ducts extend around the perimeter of each of the upper tube plates 58A, 58B. The tube plates are freely movable axially of the tubes and are connected to the structure by flexible bellows 90A, 90B which are protected from ash &e. in the flue gases by shields 92A, 92B. Air tapped from the main stream passing over the tubes, flows through a narrow gap provided between each tube plate edge and adjacent walls 88A, 88B of the supporting structure, to the space behind each bellows member, whereby the latter is kept cool and may therefore be made of a relatively cheap steel. The cooling air passes thence to the ducts 102, 102A by way of apertures 98 in the walls 88A, 88B; and is discharged from the ducts through an outlet 110. |
