Studies of steam-hydrogasification, steam reformer and sulfur removal system to produce synthesis gases from biomass for synthetic fuel production

Biomass has played an important role in providing energy worldwide. Much research has been performed to convert biomass to energy by using clean technologies. Among these researches, the CE-CERT has developed a process for synthetic fuel production from biomass and other carbonaceous matter. This process consists of steam-hydrogasification, sulfur removal, steam reforming and Fischer - Tropsch synthesis. The present work had three objectives to characterize steam-hydrogasification by introducing steam and to determine optimal operating conditions of steam methane reforming (SMR) process to obtain low H2/CO ratio of synthesis gas and to find the effects of operating variables using zinc oxide sorbent in order to obtain sulfur capture capacity under high moisture condition.; First, Hydrogasification was studied in the presence of steam using a micro batch reactor.{09}The result showed that steam significantly increases not only the rate of the hydrogasification reaction but also the conversion of carbon into product gases.{09}The enhancement of the formation of total carbon-containing gases (CH4, CO, CO2 and C2+) by adding steam is estimated to be as high as 30 times greater compared to dry hydrogasification at 1043K. Increased hydrogen pressure also enhanced methane formation in the product gas.; Second, steam-methane reforming (SMR) reaction was studied using a tubular reactor packed with NiO/gamma-Al2O3 catalyst to obtain synthesis gases with H2/CO ratios optimal for the production of synthetic diesel fuel from steam-hydrogasification of carbonaceous materials. Pure CH4 and CH4-CO2 mixtures were used as reactants in the presence of steam. With pure CH4 as the feed, H2/CO ratio of synthesis gas could not be lowered to the optimal range of 4 ∼ 5 by adjusting the operation parameters, however, the limitation in optimizing the H2/CO ratio for synthetic diesel fuel production could be removed by introducing CO2 to CH4 feed to make CH4-CO2 mixtures. The model using ASPEN Plus satisfactorily simulated changes of H2/CO ratio versus the operation parameters as well as the effect of CO2 addition to CH4 feed.; Third, removal of H2S by zinc oxide sorbent was studied using a packed-bed reactor for cleaning up the gas produced from steam-hydrogasification of carbonaceous materials. Experimental runs were conducted to monitor sulfur removal efficiency and H2S breakthrough time versus various operation parameters such as temperature, steam content, space velocity, inlet H 2S concentration, and sorbent particle size. Initial H2S removal efficiency exhibited a maximum around 561 K. Varying the steam content of inlet gas affected the equilibrium of sulfur removal by the sorbent in a reversible way. Increasing the space velocity decreased H2S breakthrough time, i.e., sulfur capture capacity of the sorbent significantly. Inlet H 2S concentration dramatically affected sulfur capture capacity of the sorbent. Sorbent particle size was varied in order to look into the effect of intraparticle diffusional limitation.