Abstract:

A bubble column carbonation reactor was set up. The CO₂ mineralization capacity through the direct aqueous carbonation of carbide slag under ambient temperature and atmospheric pressure was evaluated. The effects of the important operating parameters, including the superficial gas velocity, liquid to solid ratio and CO₂ concentration, on the capacity of CO₂ mineral carbonation and carbonation efficiency of carbide slag were revealed. The response surface model was built to analyze the effects of the operating parameters and to obtain the maximum of the carbonation efficiency. The results indicated that the increase in the gas velocity was beneficial to the calcium ion dissolution and CO₂ absorption, but it will have the gas channeling effect in the reactor when the gas velocity was high, which has an effect on the solid-liquid mass transfer and reduces the carbonation efficiency. When the liquid to solid ratio reduced, the concentration of calcium ions rose, which was good for the carbonation reactions. However, when the liquid to solid ratio was very small, it was disadvantageous for the solid-liquid mass transfer. Proper increase in the CO₂ concentration was beneficial to enhance the carbonation efficiency. When the CO₂ concentration increased to a certain level, it had a rare effect on the carbonation efficiency. According to the response surface modeling, the impact degree on the carbonation efficiency ranged as liquid-solid ratio > CO₂ concentration > superficial gas velocity. The optimization carbonation efficiency was 93.58% found by the response surface optimization, and the corresponding superficial gas velocity was 0.07m/s, the liquid-solid ratio 8.26mL/g and the CO₂ concentration was 20.91%. Therefore, the results showed that it had a good CO₂ mineralization capacity and a high carbonation efficiency for the direct aqueous carbonation of carbide slag under ambient temperature and pressure in a bubble column. This study provides the theoretical data for CO₂ capture by aqueous mineral carbonation of carbide slag. Accelerated carbonation of carbide slag in the bubble column is a promising process for CO₂ capture due to its higher carbonation conversion of carbide slag within a shorter reaction time.

Key words: bubble column reactor, greenhouse gas, CO₂ capture, multiphase reactor, accelerated carbonation, response surface model, carbide slag

摘要：

搭建了鼓泡床碳酸化反应器，研究常温常压下电石渣直接液相碳酸化矿化封存CO₂的能力，揭示了重要操作参数表观气速、液固比和CO₂浓度对电石渣矿化封存CO₂能力和碳酸化效率的影响规律。同时构建响应面模型，分析各参数对电石渣碳酸化效率的影响强度，优化获得最大碳酸化效率及相应操作工况。结果表明，增加气速有利于钙离子溶解和CO₂吸收，但反应器中过高气速易导致气相通道效应，不利于气液充分接触。当液固比降低，溶液中钙离子浓度提高，更有利于碳酸化反应，但液固比过低会影响固液间传质。适当增加CO₂浓度有利于提高碳酸化效率，但CO₂浓度增至到一定值后，对碳酸化效率影响降低。响应面建模分析发现，各因素对碳酸化效率影响顺序为：液固比>CO₂浓度>表观气速。优化结果发现碳酸化效率最高为93.58%，工况为表观气速0.07m/s，液固比为8.26mL/g和CO₂体积分数为20.91%。研究可知，鼓泡床中常温常压下电石渣直接液相加速碳酸化反应，具有较大的CO₂固定量和高的碳酸化效率，实验结果为电石渣加速矿化封存CO₂技术的发展提供了基础数据。

关键词: 鼓泡反应器, 温室气体, 二氧化碳捕集, 多相反应器, 加速碳酸化, 响应面模型, 电石渣