Thermal behavior and kinetics analysis of co-combustion of petroleum coke and paper sludge-derived hydrochar.

The co-combustion reactivity and kinetics of petroleum coke (PC) and paper sludge-derived hydrochar (PS) were investigated via thermogravimetric analysis. The physical and chemical structure features were also systematically tested. The results show that the combustion process of PS could be divided into three stages, while for PC only one stage could be clarified. Due to high volatile content, developed pore structure and low carbon-order degree, the combustion reactivity of PS was higher than that of PC. Although the ignition property of the blends could be significantly improved by addition of PS, it changed little for the burnout temperature and as a result the combustion intensity was deteriorated. For the samples with addition of PS from 20 % to 80 %, the comprehensive combustion index decreased from 3.69 × 10-15 to 2.12 × 10-15. The Kissinger AkahiraSunose model-free method was used in the co-combustion reaction of PC and PS, and good fitting results were obtained. For different samples with varying addition of PS, the activation energies were in the range of 107.51-198.44 kJ/mol, with the lowest value obtained at 20 % of PS, which was also the optimum proportion for co-combustion of PC and PS.

Study on CO2 gasification properties and kinetics of biomass chars and anthracite char.

The CO2 gasification properties and kinetics of three biomass chars (WS-char, RL-char and PS-char) and anthracite char (AC-char) were investigated by thermogravimetric analysis method. Three nth-order representative gas-solid reaction models, random pore model (RPM), volume reaction model (VM) and unreacted core model (URCM) were employed to describe the reactive behavior of chars. Results show that gasification reactivity order of different chars from high to low was WS-char, PS-char, RL-char and AC-char. In addition, the chemical components as well as physical structures of four chars were systematically tested. It was found that gasification properties of char were determined by carbonaceous structure. It was concluded from kinetics analysis that RPM model was the best model for describing the reactivities of biomass chars and VM was the model that best fitted the gasification process of anthracite char. The activation energies obtained for the biomass and anthracite char samples lie in the range of 236.4-284.9 kJ/mol.