Micro-explosion of liquid intermediates during the fast pyrolysis of sucrose and organosolv lignin

• A commercial pyroprobe was modified to perform micro-explosion visualization studies.
• A methodology is proposed to describe of the dynamics of bubble formation in Organosolv lignin and sucrose.
• A population balance model is proposed to estimate overall rates of bubble birth and death, bubble bursting, and aerosol ejection.

A new methodology has been proposed to describe of the dynamics of bubble formation during pyrolysis of Organosolv lignin and sucrose (surrogates for biomass) using fast speed visualization (125fps) with mathematical modeling. The model uses a population balance to predict overall rates of bubble birth and death, bubble bursting, and aerosol ejection. The experimental studies were performed on a uniquely modified CDS Analytical Pyroprobe 5000 to visualize the formation of bubbles within the liquid intermediate phase at heating rates close 100 °C/s. Experimentally, we observed that bubbles follow a log-normal distribution versus bubble size within the liquid intermediate phase for both materials. This distribution function changes over time due to increased viscosity from solidification reactions that generate char and the changes in the rate of bubble formation. Micro-explosion intensity was used to estimate aerosol ejection intensity. The model predicts aerosol ejection yields of 21.18% w/w from Organosolv lignin and 17.40% w/w from sucrose during pyrolysis with an average droplet size of 10 μm.