Collection Of Condensed Vapors from Biomass Slow Pyrolysis Processes
Muhammad Wasiq Riaz, Andrea Facchin, Vincenzo Gentile, Cristian Torri, PAOLO TRONVILLE, Politecnico di Torino
Abstract Number: 611
Working Group: Control and Mitigation Technology
Abstract
Biomass pyrolysis can produce charcoal for several applications. For example, the “Biomet” project studies how to transform the wood waste of the furniture industry into a renewable carbon-rich char for metallurgical use.
Along with char, biomass pyrolysis produces a gas (syngas, formed by hydrogen, carbon monoxide, methane, and other incondensable) and a condensable liquid. Upon cooling, the latter yields an ultrafine aerosol whose separation is required to obtain a clean gas, reduce environmental pollution, and turn it into a resource whenever possible. The liquid obtained from slow pyrolysis (also called wood vinegar) can be considered a high-value by-product in the preparation of biochar by biomass pyrolysis. As a natural fungicide, wood vinegar has great potential to control plant disease, achieve more sustainable agriculture, and avoid the massive use of pesticides.
We present some experimental results obtained employing a slow pyrolyzer operating with a closed-loop principle to produce metallurgical char and slow pyrolysis liquid and relatively clean syngas. The FumeCatch reactor adopts an innovative cooling-down principle and a cyclone to maximize the separation of condensed vapors. It cools down suddenly the pyrolysis fumes, mixing the hot flow with a recirculated cold fraction. This way, we can study the effect of the cooling and cyclone collection efficiency on yield and composition in the pyrolysis liquid. Aerosol collection efficiency was quantified, showing cyclone geometry’s and operating parameters’ important effect on the collection efficiency.
Quantifying and analyzing this new technology’s prototype output showed some promising results. The biochar yield with slow pyrolysis of wood waste exceeded 30% by mass. The chemical analysis of the obtained bio-oil suggests that Fumecatch collects primary pyrolysis products of slow pyrolysis, minimizing the unwanted post-pyrolysis reactions (e.g., formation of polycyclic aromatic hydrocarbons and other secondary products). Water constitutes most bio-oil, accounting for 67% by mass; the remaining 33% comprises various chemicals (acetic acid, levoglucosan). According to the results, FumeCatch can be considered a relatively simple way to recover the condensable/aerosol-forming fraction from slow pyrolysis. Hence, it can decrease the amount of particulate matter released from small-scale thermal treatment devices and maximize wood vinegar production with relevant applications in several decentralized biomass valorization schemes (e.g., charcoal manufacturing and agricultural residue management).
This study was carried out within the MICS (Made in Italy – Circular and Sustainable) Extended Partnership and received funding from Next-GenerationEU (Italian PNRR – M4 C2, Invest 1.3 – D.D. 1551.11-10-2022, PE00000004).