The Institute of Paper Chemistry

Timothy B Cartwright

David T Clay

Pulping liquor, which has been pre-concentrated to at least 50 weight percent solids, is dried in a fluidized bed dryer to produce a solid in particulate form. In the fluidized bed dryer, pre-formed particulates are fluidized by a gaseous medium substantially of superheated, unsaturated steam, and additional heat is supplied to the fluidized bed by higher pressure saturated steam passing through heat-exchange tubing within the fluidized bed region. Pulping liquor is introduced into the fluidized bed where the superheated steam vaporizes a substantial portion of its water content. The fluidizing steam becomes substantially saturated during its passage through the region of the fluidized bed, and a substantial portion of this substantially saturated steam is used upstream to pre-concentrate the pulping liquor. The solid particulates that are continuously withdrawn from the region of the bed have several advantages relative to a pulping liquor as a fuel for a pulping chemical recovery furnace, including increased thermal efficiency and storability until time of use.

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Appleton, WI, United States of America

Timothy B Cartwright