电厂烟气低浓度CO2的粉煤灰直接液相矿化技术

以粉煤灰为原料采用直接液相法矿化封存燃煤电厂烟气中CO2是一种适合我国国情的新型CO2捕集与利用一体化技术。本文考察了粉煤灰物相组成、温度、固液比、气速、压力等工艺条件对矿化反应的影响，采用X射线粉末衍射、热重分析等手段研究了温和条件下粉煤灰的矿化反应机制。研究表明，增大悬浮液固液比能够有效增加CO2捕集能力但是会降低钙的转化率；烟气流速超过一定值后，CO2溶解成为决速步，Ca转化率达到饱和；温度对矿化反应有重要影响，对工艺温度条件的研究是进一步提高矿化反应效果的关键。当反应条件为温度60 ℃、固液比100 g/L、烟气流速350 mL/min时，北京粉煤灰对CO2的封存能力达到最大值（66 kg CO2/t粉煤灰，?Ca=50.86%）。基于该技术设计了5万t/a CO2直接液相矿化装置，估算了设备投资和运行成本。与国外采用天然矿石原料的CO2矿化技术相比，该技术反应条件更加温和，同时实现粉煤灰利用与温室气体减排，技术前景广阔，对我国未来实行碳中和目标具有价值。

new direct aqueous mineralization process to capture low concentration CO2 from power plant flue gas using fly ash

The direct mineralization process using fly ash to storage CO2 from coal-fired power plant would be a suitable emission reduction technology for China.This paper investigates the effects of process conditions such as chemical and phase composition of fly ash,temperature,gas flow rate,solid to liquid ratio,gas velocity and pressure on the carbonation reaction.The X-ray powder diffraction(XRD)and thermogreviamic analysis(TGA)method were used to study the carbonation reaction mechanism of fly ash with CO2.The results indicate that,increasing the solid to liquid ratio could effectively improve the CO2 sequestration capacity but decrease the Ca conversion rate.When the flue gas velocity exceeded a certain value,CO2 dissolution became the rate-determining step,and the Ca conversion rate reached saturation.The temperature had an important effect on mineralization reaction,studying the process temperature was the key to further improve the effect of mineralization reaction.The maximum CO2 sequestration capacity of Beijing fly ash reached 0.066 kg CO2/kg fly ash(?Ca=50.9%)at 60℃with the solid/liquid ratio of 100 g/L and the gas flow rate of 350 mL/min.Based on this technology,a 50000 t/a CO2 direct aqueous mineralization device was designed,and the equipment investment and operation cost were estimated.Compared with the foreign carbon dioxide mineralization technology using natural ore raw materials,the reaction conditions of this technology are more mild,and the utilization of fly ash and greenhouse gas emission reduction can be realized at the same time.The technical prospect is broad,which is of great value to the future implementation of carbon neutralization target in China.