Bench-scale gasification of cedar wood – Part I: Effect of operational conditions on product gas characteristics

Abstract

The present study was conducted within the framework of R&D activities on the development of gasification and reforming technologies for energy and chemical recovery from biomass resources. Gasification of the Japanese cedar wood has been investigated under various operating conditions in a bench-scale externally heated updraft gasifier; this was followed by thermal reforming. Parametric tests by varying the residence times, gasification temperatures, equivalence ratios (ERs) and steam-to-carbon (S/C) ratios were performed to determine their effects on the product gas characteristics. Thermodynamic equilibrium calculations were preformed to predict the equilibrium gas composition and compared with the experimental value.We found that the product gas characteristics in terms of the H2/CO ratio, CO2/CO ratio, and CH4 and lighter hydrocarbons concentrations are significantly affected by the operating conditions used. Increasing the residence time decreased the CO2/CO ratio; however, a nominal effect was noticed on H2 concentration as a function of the residence time. At sufficient residence time, increasing the temperature led to higher H2 yields, CO efficiency and higher heating value (HHV) of the product gas. The presence of steam during gasification effectively enhanced the proportion of H2 in the product gas. However, higher S/C ratio reduced the HHV of the product gas. Increasing the ER from 0 to 0.3 increased the H2 yields and CO efficiency and decreased the HHV of the product gas.The evolution of CH4 and lighter hydrocarbons at low gasification temperatures was relatively higher than that at high temperature gasification. The evolution of CH4 and lighter hydrocarbons at high gasification temperatures hardly varied over the investigated operating conditions.