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The moisture applicator for the C single face web works by humidification with low pressure saturated steam, that is applied on the bridge between the B Flute and triple pre-heater. Duly reduced, low pressure, saturated steam from the showers general steam line is used, so that vaporization occurs near the condensation point. Furthermore, at the point were the equipment is placed, the single face web is already cold and it is, therefore, able to condense steam coming from showers. This humidity application to the C single face web permits correction of the tendency to appear the warp phenomenon that takes place in double-double, specially, when producing heavy quality productions. MOISTURE APPLICATOR The equipment consists of two parallel squared pipes, in contact, placed perpendicularly to the board direction and covering all its width. The first pipe is heated continuously with steam and, at the same time, this pipe is heating the moisture applicator pipe, were the calibrated orifices are placed. This way, condensate in the moisture applicator is avoided. The first pipe is feed with continuous steam through a spiral and it is drained through a steam trap, so it is condensate free. There is a second steam feed in this pipe, controlled with an automatic proportional valve which supplies controlled pressure, according to moisture needs. The proper moisture applicator pipe has, as well, squared section and same dimensions as the former. However, this pipe has calibrated orifices and it is divided in 5 chambers: a central chamber and two outer chambers, which are subdivided into two more chambers, each. Each one of the 5 chambers in the second pipe are feed with steam from the first pipe, through 5 on/off valves. The first pipe, heater and dispenser, is feed with a proportional control valve which is controlled from a PLC. This control can work manually, through a tactile screen, or automatically, by receiving a process signal (such as production speed), establishing, in any of the two cases, a pressure set point in the range 0-100% of the moisture application capacity. The second pipe, the applicator pipe, also controlled by the PLC, will moisten the desired width, since the application width is perfectly adjustable to the web’s width. |
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Moisture Applicator |
