| 摘要 |
A drum structure for drying a sheet of material characterized by having means to control the heating profile along the length of the drum and thus control the amount of heat applied across the width of the web or paper being engaged by the drum. To control the heating profile, the rate of heat transfer of the heating medium such as steam is varied along the axial length of the drum by selectively mixing a non-condensible medium with the heating medium to reduce the rate of heat transfer. In one embodiment of the drum structure, the drum is provided with a plurality of sub-chambers formed by axially spaced interior partitions which sub-chambers enable control of the rate of heat transfer to the drum surface associated with each sub-chamber. In another embodiment, the inner surface of the drum is provided with axially spaced grooves and the drum has a second header for a non-condensible medium, which header has means to introduce the non-condensible medium to each groove to control the rate of heat transfer at the groove.
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