利用粉煤灰与可循环碳酸盐直接捕集固定电厂烟气中二氧化碳的液相矿化法

A New Direct Aqueous Mineralization Process Using Fly Ash and Recyclable Carbonate Salts to Capture and Storage CO2 From Flue-gas

提出了采用可循环碳酸盐混合物促进粉煤灰在液相中捕集封存燃煤烟气中CO2的工艺,考察了3种中国粉煤灰的矿化性质,并对神府煤粉煤灰做了重点研究,考察不同添加剂、Na2CO3浓度、不同气氛、固液比、搅拌速度、温度等参数对神府煤粉煤灰矿化反应的影响。提出了以碳酸盐混合物为添加剂的新思路,并实验验证了添加剂循环使用的途径和方法。试验选取Ca转化率（ζCa）和产物中的CaCO3含量两个指标对矿化效果进行评价。采用XRD和SEM对粉煤灰进行物相分析和形貌分析,采用TGA测定反应后固体产物中二氧化碳的吸收量,采用总碳和无机碳分析仪对试验所得液体产物进行碳含量分析。结果表明固液比、搅拌速度对ζCa的影响非常小,而提高反应温度能显著提高ζCa。当以Na2CO3为添加剂时,矿化效果最好,Na2CO3的最佳浓度为0.5mol/L,Na2CO3在矿化过程中可以再生从而实现循环利用。

This paper introduced a new aqueous mineralization process using fly ash and recyclable carbonate salts to capture and storage CO2 from flue-gas. The carbonation performance of three different Chinese fly ash were studied, especially the one from Shenfu coal. The mineralisation process was optimized by different additives, the concentration of Na2CO3, different atmosphere, solid to liquid ratio, stirring rate and reaction temperature to improve the understanding of the effect of various operating parameters on carbonation efficiency. The carbonate salts were introduced as additives and can be regenerated in multi-cycle process, making the reaction more efficient. The total calcium content （Catot~） and the carbonation efficiency （ζca） were used to determine the perfomance of the carbonation. The crystalline phases and the structure of the raw materials were determined by XRD and SEM. The amount of CO2 in the carbonated product was determined by TGA. Total carbon and inorganic carbon （TIC） was determined by a Shimadzu TOC-L CPH analyser. The results showed the stirring rate and solid/liquid ratio have very small influence on carbonation efficiency and increasing the temperature can significantly improve carbonation efficiency. The results indicated that the highest carbonation efficiency was reached in the presence of 0.5mol/L Na2CO3. The multiple-cycle experiments showed that Na2CO3 facilitated the precipitation of calcium carbonate and was well regenerated in the process.