Study Pulp Digester

J. Stone First, I should say that hardwoods behave very differently from softwoods. With softwoods it is necessary to pulp to low yields and remove the lignin to a very great extent to make the material digestible. But with hardwoods—birch is the wood that we have studied chiefly— comparatively mild chemical treatments can increase digestibility very markedly. The degree of swelling also increases very markedly. I would therefore say that coniferous woods are unlikely to be convertible into animal feeds at an economic cost. With hardwoods on the other hand, certain mild chemical or physical treatments without appreciable lignin removal may very well be economically feasible. ... 

The Kraft process is not only the dominant chemical pulping process, but also the most important overall concerning the various production methods. Several studies have been reported on modeling of continuous digesters at different levels of complexity. Michelsen and Foss (1996) have developed a dynamic model that describes the transfer... 

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