Experimental investigations of pyrolysis and char conversion kinetics in a well-stirred reactor under atmospheric and pressurised conditions

Copyright: © WSA Fourier-Transform Infrared Spectrometer (FTIR) with IR source and HeNe laser in operation

The Oxyflame project A1 investigates the reactive conversion of biomass and its structural components cellulose, hemicellulose and lignin. The aim is to experimentally determine the reaction kinetics, i.e. the time-dependent release of the reaction products, and to derive suitable models. The focus is on two sub-processes, pyrolysis and char conversion. Pyrolysis refers to the process of releasing volatiles (e.g. hydrocarbons and nitrogen compounds) under inert conditions, while char conversion describes the reaction of the remaining, carbon-containing residual particle with oxygen, carbon dioxide or water vapour.

The reaction conditions chosen are high temperatures and particle heating rates, which represent typical boundary conditions of industrial furnaces or reactors. In the laboratory, these conditions are approximated by a fluidised bed reactor (FBR), in which high heating rates and infinitely long residence times until complete burnout can be realised. These long residence times are a significant advantage of the system, as the process of char conversion is typically much slower than that of pyrolysis. In the reactor used, pyrolysis and char conversion can be investigated separately, and their kinetics can be determined in the range of 1 – 10 bar, as well as for variable atmospheres (N2, O2, CO2, H2O). The experimentally obtained data will be used to calibrate or validate existing kinetics models of different complexity. These models are then used by other projects of the collaborative research centre in the simulation of the overall process.