Volatiles effects on the thermal and chemical structures of H_2 production in a hybrid porous media reactor using solar steam

摘要

A numerical simulation was performed to model the gasification of carbonaceous feedstocks inside a batch reactor operating on a hybrid filtration combustion mode in presence of solar steam aiming to hybridize conventional process. Results were validated against empirical data collected using sub-bituminous coal, focusing in the effect of implementing a volatilization model to the simulation. Temperature and concentration of gaseous products of the combustion wave were reported as function of steam presence, filtration velocity and fuel content inside the porous bed. Solar steam was produced in a hybrid thermal/electric boiler powered by a PV-array and heat pipes, achieving up to 19% of concentrated solar input in the generation of steam. Numerical simulations showed a good qualitative agreement with experimental results. The main numerical and empirical results showed that increasing the coal presence favored a normal thermal structure, observing a maximum temperature of 1,638 K at a 70% coal mass fraction, while an increase on the steam content resulted on a shift from a normal to an inverse thermal structure recording a peak temperature of 1,618 K at a 0.95 H_2O/O_2 fraction and 50% coal presence. Finally, H_2 production was observed to increase with an increment of coal fractions which was only properly simulated when including a devolatilization model.