GB1341328A - Paper machine broke control - Google Patents

Abstract

1341328 Paper-making L A McKEOWN 28 Feb 1972 9010/72 Heading D2A In the event of malfunctioning of a papermaking machine the machine is kept running on substantially broke stock, the normal stock supply being restricted. The normal stock comprises virgin groundwood fibre, unbleached sulphite stock and broke stock which are proportioned in a metering box 20 and then supplied to a fourdrinier section 35 of the machine via a mixed stock box 21 which may be omitted if not required, a machine chest 23, a stuff box 25 and a headbox 34. The stuff box is a constant head type, the stock flowing by gravity from section 26 through section 27 and overflow surplus stock being recirculated through the machine chest. The stock is blended with white water from a wirepit 31 and pumped to the headbox 34. Couch pit 40 collects excess stock and if there is a wet end break all of the broke stock. Usually some of the wet broke is thickened on a broke filter and stored in a stock chest 42 from which it is pumped to a broke storage tank 44. When there is a wet end break, however, some of the broke stock is pumped direct from the couchpit 40 to the tank 44 or to a broke blend tank 15. Dry end broke is treated in a beater 45 and then pumped to the tank 44. When the tank 44 is full the stock may be pumped from it to a groundwood storage chest 11. When the apparatus is operated in accordance with the invention the stock from the machine chest 23 is restricted and the broke stock is pumped through a pipeline 60 direct from the tank 15 to the stuff box 25 and the overflow from this is returned to the tank 15 through a pipeline 61. Alternatively, broke stock is pumped from the couchpit 40 through a pipeline 65 and this may enter the suction of the machine chest pump, or the stock may be fed from the chest 42 to the stuff box 25, or from the couchpit 40 or the chest 42 to a fan pump 32 feeding the headbox 34, or the stock may be fed to a point just before the outlet of the headbox 34. Other pulp or white water may be added to the broke stock.