Coal gasification process driven by concentrated solar radiation for carbon neutralization: Reaction and energy characteristics

Abstract

Solar-driven gasification products for chemical feedstock are one of the effective means to utilize coal in a low-carbon and resourceful way. However, few studies on the reaction and energy characteristics are based on experimental data of concentrated solar coal gasification. This study designed a novel experimental solar radiation gasification thermogravimetric device. An energy model of a solar radiation dish thermochemical conversion system was also developed. Compared to indirect radiation, direct radiation has a 10 % higher carbon conversion rate, an increased energy upgrade factor (up to 0.86), and a 38.5 % increase in energy conversion efficiency. Furthermore, we investigate direct radiation-catalyzed gasification to assess the effects of different types and ratios of catalysts. The results showed that the catalytic effect of K2CO3 was better than that of Na2CO3, which would improve the energy conversion efficiency by 4.8 %. For K2CO3, the efficiency was increased by 14.1 % through increasing the doping ratio from 5 % to 10 %. Meanwhile, this study analyzed the reaction kinetics of direct radiation-catalyzed gasification. Finally, we constructed a solar concentrating radiation dish thermochemical conversion system model based on the experimental data. We found that the system energy efficiency in the direct radiation form was 15.3 % higher than that in the indirect radiation form; besides, adding the catalyst in the direct radiation form increased the energy efficiency by 23.8 %. We also found that the gasifier exergy efficiency in direct radiation catalyst gasification was 29.7 %, and that of indirect radiation gasification was 7.23 %. The monthly solar exergy distribution follows the solar radiation closely. The results guide the chemical process of solar thermal conversion.