| 摘要 |
<p>The present publication discloses a steam box comprising means (4, 10, 13, 16) for distributing steam onto a web (1) being calendered, at least one valve (5, 6, 7) connected to said steam distributing means and capable of controlling the blowing of the steam onto the web (1) and elements (3, 25, 15, 16, 9) for feeding hot steam to the valve (5, 6, 7). The invention is based on having in each valve (5, 6, 7) at least three steam channels, namely an inlet channel (22) for feeding the steam to the valve, an outlet channel (23) of the valve for feeding the steam onto the web (1) and a recirculation channel (24) for recirculating the steam, and a check element (20) for controlling and dividing the incoming steam flow from the inlet channel (22) between the outlet channel (23) and recirculation channel (24) of the valve, and a return pipe (27) connected to the recirculation channels (24) of the valves (5, 6, 7), capable of routing the steam directed to the recirculation channel (24) of the valve (5, 6, 7) to, e.g., the condensate return line of the steam distribution system. By virtue of such a circulation the valve can be kept warm even when no steam is directed via said valve, thus preventing the formation of droplets and their blowing onto the web. <IMAGE></p> |
