Application of Monte‐Carlo simulation to estimate the kinetic parameters for pyrolysis—Part I

Abstract

A mathematical model was developed to represent pyrolysis. The components of primary and secondary pyrolysis reactions were simply lump into different groups and were represented through a set of pseudo-first-order reactions. This study presents an algorithm to estimate the kinetic parameters using Monte-Carlo (MC) simulation. The combination of an analytical reaction model and the MC simulation technique rapidly generates a large number of numerical values. Results show that MC-simulated data and experimental data are in fair agreement. Though the technique developed in this study proved to have potential, more experimental data are needed to check the robustness of the model. Keywords: biomass, pyrolysis, Monte-Carlo simulation, kinetic parameter INTRODUCTION Biomass is the fourth largest primary energy resource, after coal, gas and oil, in the world (Li et al., 2004). It is green, renewable and if used efficiently its CO 2 neutral. One promising route to extract energy out of biomass is via various thermo-chemical routes (i.e., pyrolysis, gasification, combustion, etc). While the product of gasification is a non-condensable gas, the product of a pyrolysis process is bio-oil (also referenced as tar or oil). Because of its high volumetric energy density compared to biomass in bulk, this bio-oil is especially attractive for transport and storage (Janse et al., 2000). Irrespective of the thermochemical route chosen to process biomass, pyrolysis is the first stage to encounter. Also during the pyrolysis step 80% of the volatile present in the biomass is released (Larfeldt et al., 2000). Therefore, sufficient understanding on pyrolysis process is very important to exploit biomass to its full potential. Di Blasi (2008);and Gronli (1995) have concluded that accurate knowledge of the reaction kinetics is a crucial parameter for a reliable modelling study. Recent reviews reveal that available knowledge on kinetics is not enough to confidently design a pyrolysis reactor (Wang et al., 2005;Boukis et al., 2007;Basu and Kaushal, 2009). Though the literature is full of references to model pyrolysis, however selection of pyrolysis kinetic is often the weakest link otherwise a very good model (Lopez et al., 2002;Vamvuka et al., 2003;Li et al., 2008;Wang et al., 2008;Park et al., 2009). To cope with the diversity of materials pyrolysed (Wood, forest waste, dedicated crop, MSW, etc.) and with the numerous reactor types (Fixed, fluidized, entrained, etc.) general but reasonably accurate kinetics are required. In this study, we present an analytical forward model and a backward procedure based on the Monte-Carlo (MC) approach to estimate the reaction constant parameters. Accurate analytical or numerical modelling of the pyrolysis processes is essential to understand and design commercial-scale processes. PYROLYSIS REACTION KINETICSWhen the dried fuel is heated in the range of 200-500• C in absence of oxygen, it is decomposed into solid char, volatiles or bio-oil (condensable hydrocarbon) and gases. The relative yield of gas, liqu...

Economic trends for temperature of sugarcane bagasse pyrolysis

“…Compounds with longer and heavier molecules are broken into smaller and lighter molecules. The main types of thermochemical conversion processes can be represented by combustion, gasification, hydrogenation, liquefaction, and pyrolysis …”