Papermaking machine with jet- or spray coating unit for e.g. starch solution, includes provisions for cleaning and avoiding contamination of machine assembly

The coating unit (1) is equipped to avoid contamination of the machine assembly. It includes a rinsing or spraying unit (11). Provision is made to clean the unit from its interior or exterior, especially to clean the spray pipe. The unit includes a flushing pipe running at fixed spacing from the spray- (or jetting) pipe (2), parallel to its longitudinal axis. Nozzles (12) spray cleaning fluid (or water) onto the spray pipe or its casing. The unit has a casing (5) with an inner wall and outer wall around it. The housing includes a cooling unit (8), especially with cooling chambers, to condense the mist of coating medium caused by spraying. A channel (9) collects the condensate. An extraction unit removes spraying mist. Air flows are produced to blow mist into the extraction unit. The unit (1) includes a lower rinsing channel (13). Damaging temperature gradients and air flows are avoided. Suitable baffles, seals, suction units and blowers are used to cause opposing airflows. A number of smaller spray tubes (10) branch off from the main spray pipe, and coat the material onto the fibrous web (20). Mutual spacing between nozzles or tubes on the spray pipe is less than 50 mm. The coating is applied to a web made from a pulp suspension at less than 40[deg]C. Leading process parameters include coating medium concentration of 3%-5% in solution, and application at a rate of 0.7-1.5 g/m2> under a pressure of about 3 bar. An independent claim is included for the corresponding method of coating. Eine Maschine zum Herstellen einer Papier-, Karton-, Tissue- oder einer anderen Faserstoffbahn mit einer insbesondere ein Sprüh- oder Strahlrohr (2) aufweisenden Vorrichtung (1) zum Auftragen eines fluiden Auftragsmediums, insbesondere von Stärke, ist dadurch gekennzeichnet, dass die Vorrichtung (1) ein Mittel zum Verhindern von Verschnutzungen eines Aggregats der Maschine umfasst.