Pilot Plant Experiments on Wood Hydrolysis

Research for improvements in the process of hydrolysis with dilute acid were discontinued in Germany at an early date. The follo ving 

Tarry material was carried along with the wood hydrolyzate and deposited on cooling surfaces or in parts where flow was restricted. For that reason it was necessary to use gate or lubricated plug valves for all hydrolyzate lines. Heat exchangers for conserving heat in the liquor could not be used because of the fouling effect of the tar that precipitated on the tubes. 

The material used for hydrolysis, because of its lower cost, is the by-product from various wood-using industries. It consists of mill waste from sawmills and woodworking industries in the form of slabs, edgings, shavings, sawdust, cull veneer and trimmings of shredded wood waste from the solvent extraction industry for rosin and of cull wood that may be removed from cut-over wooded areas as a part of a forest management program. 

Douglas fir hogged waste (best material removed) 50.9 42.1 

For the hydrolysis operation, it is desirable that the dilute acid be in contact with all parts of the chip, and that the chip be small enough to permit rapid diffusion of the acid into the chips and of the sugar out of the chips. For this operation, the smaller the wood particle the better, because the diffusion is increased as the smaller size of the chips decreases the distance to be traveled. 

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