Mo Och Domsjo Aktiebolag

Lars G Norehall

Per A Hillstrom

A process is provided for continuously washing fibrous suspensions in aqueous suspending liquors containing dissolved impurities to remove such impurities by exchanging aqueous suspending liquid substantially free from such impurities for the aqueous suspending liquor, which comprises washing fibrous material of the suspension in aqueous suspending liquid substantially free from dissolved impurities; and forming a washed fibrous suspension in such liquid; withdrawing aqueous suspending liquor containing dissolved impurities; diluting the washed fibrous suspension by adding aqueous suspending liquid substantially free from dissolved impurities; measuring the volume amount of such diluting aqueous suspending liquid added; measuring the volume amount of diluted washed fibrous suspension; and then adjusting the volume amount of wash liquid added to maintain substantially constant the difference between the amount of wash liquid added and the liquid content of the undiluted washed fibrous suspension.

Process and apparatus for continuously washing aqueous fibrous

A process and apparatus are provided for controlling the supply of aqueous suspending liquid in continuously washing fibrous suspensions in aqueous suspending liquors containing dissolved impurities, to remove such impurities by exchanging aqueous suspending liquors substantially free from such impurities for the aqueous suspending liquor, which comprises washing fibrous material of the suspension in aqueous suspending liquid substantially free from dissolved impurities, and forming a washed fibrous suspension in such liquid; withdrawing aqueous suspending liquor containing dissolved impurities; diluting the washed fibrous suspension by adding aqueous suspending liquid substantially free from dissolved impurities; determining the amount of dissolved impurities remaining with the fibrous suspension after the washing has been completed by measuring (1) the volumetric flow rate of the washed suspension; (2) the liquid content of the washed suspension; and (3) the content of dissolved impurities in the suspending liquid; and then controlling the volume amount of wash liquid added according to the washing losses to maintain washing losses within a predetermined limiting range.

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Ornskoldsvik, Sweden

Lars G Norehall