An approach for production of synthetic Fischer Tropsch diesel: Specific application of steam hydrogasification

A multi-step process based on steam hydrogasification to convert carbonaceous matter to liquid fuels has been developed. It is an integrated system of three different chemical processes. In the current configuration a steam hydrogasification (SHR) step is followed by a steam methane reforming (SMR) step followed by a Fischer-Tropsch reaction (FTR) step. Results have shown that the combination of steam and hydrogen in the initial gasification step offers the flexibility of using feedstock with high water content, which enhances the reaction rates more than an order of magnitude to product gas.; The SHR is the most important step in the process. The feedstock is fed along with steam and hydrogen in this reactor. It has been demonstrated that the feed composition ratio of H2O/C and H2/C and temperature and residence time are important factors governing the feasibility and performance of the process that affect the product composition and overall efficiency.; In this study I present experimental results of SHR of bituminous coal using a batch reactor and a continuous reactor (kiln type gasifier). Conversion efficiencies of coal to CH4, CO and CO, were determined at different experimental conditions. Conversion efficiencies varied between 40% to over 85% depending on experimental conditions. Also, biosolids were studied for being utilized as a feedstock in the process. Experiments of bituminous coal were also carried out in a fluidized bed reactor (CFBR). The CFBR experiments also showed conversion efficiencies with variation in temperature, H 2O/Coal and H2/C ratios. Carbon conversion from 30% to 52% was observed.; The experiments were compared to modeling results for the complete process using the ASPEN process model. Good agreement between the theoretical and experimental trends was observed. The amount of steam in the initial reactor can be used to optimize the product gas composition. The experiments show that a combination of steam and hydrogen can be used for the gasification of coal and the feed composition can be optimized to produce the required gas composition needed depending on the fuel processing requirements and catalyst.