Pyrolysis of Herb Residues: Thermogravimetric Analysis and Pellet Level Modelling

Abstract

A series of alternative energy sources have been exploited to overcome the problem, including the solar energy, wave power, wind power, geothermal heat and so on. Among these energy sources, the biomass fuel has gained a lot of attention. The thermochemical conversion technique of the biomass has been considered as one of the most promising technologies for producing alternative energy fuel, especially the fast pyrolysis process. This thesis describes the experimental and modelling research of the pyrolysis of herb residues in terms of the kinetics analysis and the pyrolysis behaviour of single particle model. The general study of the characteristics of the biomass energy feedstock is reviewed, including the biomass classification and properties, the biomass particle morphology, and the thermochemical conversion behaviour. The kinetic parameters of the herb residue pyrolysis are studied by the thermogravimetric characteristics. The master plot method is used to investigate the kinetic parameters and the reaction mechanism of herb residues pyrolysis. The optimized parameters are used in the numerical model and verified by experiment data. The catalytic behaviour of Chinese herbal medicine pyrolysis was also investigated by loading different amounts of potassium salts. The pyrolysis behaviour of single pellet is investigated by experimental and numerical study. The finite volume approach is used for developing the numerical model. The methodology of developing the population balance model and single particle model for pyrolysis are investigated. The population balance approach is not widely applied into modelling the thermochemical conversion of biomass, but this method is good to improve the accuracy of the simulation. This research gives the method of simulating the thermally thick particle model (Bi >1) for fast pyrolysis.