Final report for (open quotes)Production of mild gasification co-products(close quotes) project

摘要

The SGI International Liquids From Coal (LFC) Process is a mild pyrolysis, or mild gasification, treatment that upgrades low-rank coals by removing almost all of the moisture and a substantial portion of the volatile matter. The process produces two value-added co-products: a Coal Derived Liquid (CDL) and a solid Process Derived Fuel (PDF). A third co-product, a low-heating-value non-condensible gas, is recirculated and combusted in a commercial sized plant to provide drying and pyrolysis process heat. The LFC Process consists of three basic steps. The first step, drying, involves essentially inert gas convectively raising the coal temperature and removing most of the moisture. The drying temperature is limited to ensure that no hydrocarbon gases evolve, and the flow rate is limited below fluidization levels for most of the coal particles. The second step, pyrolysis, consists of additional inert gas heating that raises the temperature of the dried coal so that more than half of the volatile matter is removed under a controlled temperature history that is characteristic for each particular coal and customer demand. The third step, finishing or conditioning, consists of exposure to a cooling inert gas that quenches the pyrolysis reaction, followed by controlled exposure to oxygen for the purposes of stabilization. The processed solid char is then brought to moisture equilibrium (much less than the parent coal's equilibrium level), and, if necessary, a dust suppressant is added to the PDF. The PDF co-product is environmentally more attractive than the parent coal because a large fraction of the organic sulfur is removed with the volatile matter, and the heating value of the fuel is increased with a concurrent increase in combustion efficiency. When subjected to appropriate finishing steps, the PDF represents a stable, economically transportable, high-heat-value reactive combustion fuel with stable flame characteristics similar to natural gas.