Method for optimizing the liquor-to-wood ratio when producing paper pulp

摘要

Provided is a method and apparatus which decreases a liquor-to-wood ratio at the top of a continuous digester while increasing a liquor-to-wood ratio in the upstream pre-impregnation vessel. A substantially wood-chip free liquor portion is drawn from the top of the digester through a heater to the bottom of the pre-impregnation vessel through a return conduit. A stream is drawn off the return conduit, upstream of the heater, for transfer to the top of the vessel without mixing with wool chips.