GB362557A - A process of and apparatus for, washing webs of paper - Google Patents

Abstract

<PICT:0362557/IV/1> <PICT:0362557/IV/2> The washing of paper web is accompanied by friction applied over the whole width of the web and with a reciprocating movement. The friction is applied by means of a travelling band, or by means of two travelling bands between which the web passes, using apparatus in which the conveyer passes over guide rollers into and out of a bath or series of baths. In the operation of the apparatus illustrated in the drawings, a web of paper 1 saturated with sulphuric acid of high concentration passes over the driven roller 15 between two bands 19, 23, which are made of woven asbestos, a phosphor-bronze grid, or other material resistant to sulphuric acid. The web travels between these bands through all the baths 2 .. 6, taking a zig-zag course over and under the rotating rolls 13. In their passage by these rolls, the bands travel through arcs of different radii, and each band in turn has to travel through a greater distance than the other, so that the web is subjected to a pronounced rubbing treatment, and is thoroughly washed. The same rubbing effect is produced by the change of direction of the bands as they pass over the driven rollers 14 outside the baths. The endless bands travel back to the bath 2 over the driven rollers 16, 17, 18 and 22, 21, 20, being freed from fibrous material by jets 24, but one band may continue with the web until it reaches the drying device. The fresh washing water is fed through a conduit 7, and flows through overflow conduits 9, 10, 11, 12, and 8. Thus washing liquids of different concentrations are used in the baths, so that the amount of water required for washing is kept as low as possible.