Multi-cyclic CaO carbonation/calcination is an attractive method for CO_2 capture during coal combustion.However,the capture capacity of CaO sharply decreases with increasing carbonation/calcination cycles.In order to improve the stability of CO_2 capture capacity of CaO during carbonation/calcination cycles,synthetic CaO/Al_2O_3 sorbents were synthesized by two methods：wet chemistry and sol-gel-combustion-synthesis（SGCS） to make a further comparison.The results indicate that the SGCS-made CaO/ Al_2O_3 = 80：20 wt%sorbent provides a competitive performance of a capture capacity of 0.43 g-CO_2/g-sorbent after 20 cycles.
Cong Luo Ying Zheng Ning Ding Qi Long Wu Chu Guang Zheng
In this study, a detailed technical-economic analysis on a O2/CO2 recycle combustion power plant (Oxy-combustion plant) retrofitted from the existing coal-fired plant (with a capacity of 2×300 MW) in China was carried out by using life cycle assessment (LCA) and life cycle cost (LCC) method. The CO2 emissions, investment cost, cost of electricity and CO2 avoidance cost within the life cycle were calculated respectively. The results showed that the CO2 emission avoidance rate of retrofitted Oxy-combustion plant in the life cycle was about 77.09% without taking account of the CO2 compression; the annual cost increased by 5.9% approximately, the net power decreased by 21.33%, the cost of electricity increased by 34.77%, and the CO2 avoidance cost was about 28.93 USD/t. Considering the compression process of CO2, the avoidance rate of CO2 emission was about 73.35% or so; the annual cost increased by 9.35% approximately, the net power decreased by about 26.70%, the cost of electricity increased by 49.13%, and the CO2 avoidance cost was about 45.46 USD/t. The carbon tax (the CO2 tax) should be more than about 24 USD/t and 34 USD/t under the condition of considering CO2 compression or not, respectively, which is beneficial to promote transformation of existing coal-fired plant for reducing the CO2 emissions.
WANG Yun, ZHAO YongChun, ZHANG JunYing & ZHENG ChuGuang State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
