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Keywords:

  • pyrolysis;
  • char;
  • process control;
  • waste treatment;
  • waste minimization

Abstract

BACKGROUND: State-of-the-art control systems that can guarantee the pyrolytic exposure temperature are needed in the production of designer biochars. These designer biochars will have tailored characteristics that can offer improvement of specific soil properties such as water-holding capacity and cation exchange capacity.

RESULTS: A novel stochastic state-space temperature regulator was developed for the batch production of biochar that accurately matched the pyrolytic exposure temperature to a defined temperature input schedule. This system was evaluated by processing triplicate swine manure biochars at two temperatures, 350 and 700 °C. The results revealed a low coefficient of variation (CV) in their composition and near-similar 13C nuclear magnetic resonance structure as well as thermal degradation patterns. When pyrolysing at 350 °C, the stochastic state-space regulator generated a biochar with lower CV in ultimate (i.e. CHNS) compositional analysis than the original feedstock.

CONCLUSION: This state-space controller had the ability to pyrolyse a feedstock and generate a consistent biochar with similar structural properties and consistent compositional characteristics. Published 2011 by John Wiley & Sons, Ltd.