Fractionation of flash pyrolysis condensates by staged condensation
The utilization of condensates from flash pyrolysis is challenging due to several unwanted properties. The condensates consist of a mixture of many high value compounds, but each of them is only contained in a low concentration. As additional challenge instantaneous phase separation into an aqueous and a sludgy heavy organic phase takes place, if agricultural residues like barley straw are used as raw material for pyrolysis. A separation by means of distillation is not possible as the compounds undergo polymerization reactions when exposed to higher temperature. A different approach for separation based on boiling temperature is staged condensation of original vapors. Ablative flash pyrolysis is performed in a laboratory. The pyrolysis vapors are condensed in either two or three stages, each composed of a double-effect cooler followed by an electrostatic precipitator. The higher boiling fractions are low in water and acid and show a high heating value.