Numerical Simulation of Secondary Gas Phase Reactions of Coffee Grounds with a Detailed Chemical Kinetic Model

Abstract

A two stage tubular reactor (TS-TR) was developed to study vapor phase cracking of nascent volatiles generated in rapid pyrolysis of food industry residues, namely residue from industrial production of liquid coffee. Changes in gas phase compositions were monitored in the TS-TR experiments at ambient pressure, τ~6 s, and T = 973-1073 K. These experiments were numerically simulated using a detailed chemical kinetic model that comprises 543 species and 8175 elementary-step like reactions. The numerical predictions were compared with the experimental data for more than 20 molecular species for critical evaluations of the developed kinetic model. The model successfully predicted time-dependent change of concentrations of major species such as H2, CO, CO2, CH4, etc. Production of benzene as well as consumptions of minor oxygenate compounds such as acetic acid, acetaldehyde, acetone, and methanol were also fairly reproduced. The reaction pathway analysis was performed to indentify the major reaction routes leading to primary aromatic species such as cyclopentadiene and benzene which are potential precursors of tar.