Abstract
Lithium ortho-silicate (Li_4SiO_4) is one of suitable solid sorbents for capturing CO_2 from Solid Oxide Fuel Cells (SOFCs) at a high temperature. The sorbent can absorb CO_2 equivalent to about 30wt% of sorbent at temperatures around 550℃ with an exothermic reaction and regenerate at temperatures above 800℃ with an endothermic reaction. This temperature swing between the absorption and regeneration conditions significantly affects CO_2 removal due to the reaction equilibrium. In this study, performances of two types of CO_2 separation and regeneration system combined with a SOFC were evaluated by the simulation using ASPEN PLUS and the post-combustion removal system from the anode off-gas was superior to the pre-combustion removal. Some experiments under negative pressure conditions were conducted to lower the regeneration temperature and the result showed that the regeneration ratio came up around 50% under the condition of 0.3atm and 680℃ but the cycle capacity of the sorbent was reduced with number of cycles.
