Simultaneous CO2 capture and thermochemical heat storage by modified carbide slag in coupled calcium looping and CaO/Ca(OH)2 cycles

The simultaneous CO2 capture and heat storage performances of the modified carbide slag with byproduct of biodiesel were investigated in the process coupled calcium looping and CaO/Ca(OH)(2) thermochemical heat storage using air as the heat transfer fluid. The modified carbide slag with by-product of biodiesel exhibits superior CO2 capture and heat storage capacities in the coupled calcium looping and heat storage cycles. The hydration conversion and heat storage density of the modified carbide slag after 30 heat storage cycles are 0.65 mol.mol(-1) and 1.14 GJ.t(-1), respectively, which are 1.6 times as high as those of calcined carbide slag. The negative effect of CO2 in air as the heat storage fluid on the heat storage capacity of the modified carbide slag is overcome by introducing CO2 capture cycles. In addition, the CO2 capture reactivity of the modified carbide slag after the multiple calcium looping cycles is enhanced by the introduction of heat storage cycles. By introducing 10 heat storage cycles after the 10th and 15th CO2 capture cycles, the CO2 capture capacities of the modified carbide slag are subsequently improved by 32% and 43%, respectively. The porous and loose structure of modified carbide slag reduces the diffusion resistances of CO2 and steam in the material in the coupled process. The formed CaCO3 in the modified carbide slag as a result of air as the heat transfer fluid in heat storage cycles decomposes to regenerate CaO in calcium looping cycles, which improves heat storage capacity. Therefore, the modified carbide slag with by-product of biodiesel seems promising in the coupled calcium looping and CaO/Ca(OH)(2) heat storage cycles. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

The modified carbide slag with by-product of biodiesel shows superior CO2 capture and heat storage capabilities in the coupled calcium looping and CaO/Ca(OH)(2) thermochemical heat storage process. Introducing CO2 capture cycles and heat storage cycles can enhance the CO2 capture reactivity and heat storage density of the modified carbide slag.