| 摘要 |
The cooling assembly (1) to lower the temperature of a moving web (2) e.g. of paper has a cooling roller (3) and cool air (10,11) is blown at the web surface away from the roller (3), over a defined zone of the roller segment ( alpha ) where the web passes round it. The blown air pressure is over the ambient atmospheric pressure The defined blowing zone is next to the start of the roller segment ( alpha ) where the web passes round it, and has a length of at least 10 mm in the peripheral direction and covers at least 50% of the roller segment ( alpha ). The roller segment ( alpha ) covers at least 240 deg and covers more than the cooling zone length. The temp. of the blown air (10,11) is set, when blown to the exposed surface of the web (2). The air (11) is blown to the web (2) surface at a speed of 50-120 m/sec. and at a pressure of 5000-6000 Pa. At least one air bar (8) is towards the surface of the web (2) away from the cooling roller (3), connected to a compressed air supply (9). The bar (8) has a width of at least 40 mm, in the direction of web travel, and a number of bars (8) can be used with a narrow gap between them. The cooling zone is encapsulated within a housing. |
