Optimization of gas production and efficiency of supercritical glycerol gasification using response surface methodology

Biomass is a sustainable and renewable source of energy and can be an alternative to fossil fuels because of its abundance and the non-toxicity of the products obtained from its gasification. Among the heat treatments used to produce syngas is the hydrothermal gasification process, which consists in bringing a wet biomass beyond the supercritical conditions of temperature and pressure. In this paper, a kinetic mathematical model of supercritical gasification of glycerol was resolved with Mathcad 14 and assessed by comparison with experimental results from previous work reported in the literature. The effect of three parameters, namely temperature, residence time and glycerol concentration, on the efficiency of gasification, the production of gases and the lower calorific value was investigated. Using surface response methodology, three quadratic models which correlated the gasification efficiency, the gas yields and the lower calorific value (LCV), in terms of the considered factors, were also obtained and assessed using analysis of variance. Thus, optimal operating conditions were obtained and the results showed that maximum gasification efficiency, H-2, CO production and LCV responses were obtained at a temperature of 809.36 K, a residence time of 10 s and an initial glycerol concentration of 5 wt%.