Technological Solution for the Sustainability of the Destructive Distillation of Wood in Classic Horizontal Retorts

S. Tomas, M. Planinić, A. Bucić-Kojić, M. Bilić, D. Velić and M. Čačić

Abstract
Charcoal production in retorts involves the pyrolysis i.e. thermal decomposition of wood in the absence of oxygen/air. The by products of this thermo-chemical process are tar, pyroligneous acid and wood gas. Pyroligneous acid can recover in several useful organic products by fraction distillation. However, the modern synthetic ways of their production are more economic, so that distillation of pyroligneous acid becomes irrational and is an abandoned procedure in “Factory of Wood Processing in Belišæe”. The factory in full capacity makes about 25 t of pyroligneous acid daily, which is recognised as an environmental pollutant and hence cannot be allowed to escape into streams. Therefore, to continue wood charcoal production it was necessary to dispose of pyroligneous acid in an environmentally friendly manner. Four possible solutions to this problem were proposed. The innovative and acceptable solution found in the partial plant reconstruction that assumes direct combustion of exhaust retort gases instead of their condensation. The reconstruction gave several positive effects: the condensation phase was eliminated; retort gases became the main heating fuel that should provide ample heat for the plant; wastewater and gases are environmental-friendly.

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Keywords
Charcoal, horizontal retort, pyroligenous acid, sustainable charcoal production