Coal gasification with CO_2 in molten salt for solar thermal/chemical energy conversion

摘要

Coal gasification with CO_2, in Na_2,CO_3,--K_2CO_3, molten salt that was used as thermal storage for gas/solid heterogeneous reaction was studied to apply this system for solar thermal/chemical energy conversion. The reactions were performed at 1173 K under various CO_2 flow rates, weights of the molten salt and Na,CO_3/K_2CO_3 ratios. The CO_2 gas consumption rate increased with increasing CO_2 flow rate, however, the conversion efficiency of CO_2 to CO was decreased. As the weight of the molten salt increased, the rate of the gasification reaction was decreased. The maximum conversion efficiency of CO_2 to CO under the experimental conditions reached 7l/100 at the CO_2 flow rate of 3l0 pmol/s. Thus 37 J of the solar thermal energy can be converted into chemical energy per second by the endothermic process of the Boudouard reaction (C+CO_2=2CO-- l69. 16 kJ (at l 150 K); coal=l0 g), when this gasification reaction would be perfor- med by using concentrated solar heat.