Dynamic Modeling of the Coproduction of Liquid Fuels and Electricity from a Hybrid Solar Gasifier with Various Fuel Blends

摘要

A sensitivity analysis is presented of the energetic and environmental performance of a hybridized solar gasification, coal-to-liquids (CTL_(sol)) polygeneration system using a pseudo-steady-state model outlined in a recently submitted paper. The hybrid CTL_(sol) system was assumed to be integrated with pressurized (upgraded) syngas and O_2 storage to reduce the impact of solar resource transience on the unit operations downstream of the hybrid gasifier. Reported is the sensitivity of the CTL_(sol) system's energetic and environmental performance to variations in gasification reactor pressure, to turn-down in the fuel feed rate to the hybrid gasifier, to the integration of an indirectly irradiated hybrid natural gas dry or steam reforming system, and to the proportion of biomass cogasified with the coal. The energetic performance of the CTL_(sol) system was shown to be only weakly sensitive to the solar hybrid gasifier pressure. The incorporation of a natural gas steam reformer within the hybrid solar coal gasifier was shown to reduce by an additional 15% the process' mine-to-tank CO_2-e emissions relative to the configuration without the co-reformer. However, the addition of the co-reformer to the solar hybrid gasifier also reduced the solar share of the system output to 17% from 20%. The use of a dry reforming process was found to enable similar energetic and environmental performance characteristics to the steam reforming process. Mine-to-tank greenhouse gas emissions parity with diesel production from mineral sands can be achieved with a 30% biomass cogasification fraction, by weight, in a solar hybrid cogasifier, while 45 wt % biomass is required for the nonsolar equivalent. This coal-biomass solar cogasification system also achieved a 22% improvement in energetic productivity relative to the nonsolar reference system. Mine-to-tank CO_2-e emissions of 0 was found to be achievable with a biomass cogasification fraction of 60 wt %, while the nonsolar equivalent was found to require a biomass fraction of 70 wt % to enable the same outcome. Reducing the amount of biomass to achieve a given environmental target is important given that biomass is typically three to four times more expensive than coal.