CO_(2)泡沫混凝土碳封存潜力分析

Analysis of Carbon Storage Potential of CO_(2) Foamed Concrete

CO_(2)捕集、利用与封存是碳中和技术体系的重要组成部分,混凝土在大规模吸收CO_(2)方面具有巨大的发展潜力.为了掌握CO_(2)泡沫混凝土的碳封存潜力,分析了CO_(2)泡沫混凝土的固碳机制,建立了CO_(2)泡沫混凝土固碳能力的数学模型,估算了CO_(2)泡沫混凝土的固碳和储碳能力.结果表明,CO_(2)泡沫混凝土碳封存能力的99%以上是由混凝土骨架的化学碳化方式完成的,而泡孔的储碳能力较弱;按照30%碳化率估算,我国每年生产的混凝土在全生命周期内的碳封存量平均为2.18亿t,超过大兴安岭林区森林1 a的碳汇;近5年,我国CO_(2)泡沫混凝土的碳封存潜力为5.80亿t·a^(-1),在煤电一体化矿区的固废和废气资源化利用方面具有很好的应用前景.CO_(2)泡沫混凝土在凝固前的稳定性是下一步要重点解决的技术难题.

The technology of carbon capture,utilization,and storage(CCUS)is an important component of carbon neutral technology systems.To confirm the carbon storage potential of CO_(2) foamed concrete(CFC),this study addressed the principle of carbon storage in CFC materials.It is apparent that carbon storage of CFC materials includes carbon fixation in concrete skeletons and carbon storage in CFC bubbles.The carbon fixation of CFC skeletons is realized by CO_(2) mineralization.As the concrete skeleton in CFC is in the CO_(2) atmosphere,the carbonation of CFC materials or CO_(2) mineralization is more complete.Research shows that the carbonation rate of CFC materials can reach almost 30%after acidification,foaming with high CO_(2) pressure and curing in the atmosphere.The carbonation rate is higher than the rate in concrete curing with CO_(2).A mathematical model was established to calculate carbon fixation capacity in CFC materials,and the carbon fixation and storage capacity in CFC material were estimated.The results showed that more than 99%carbon storage of CFC was realized by the chemical carbonization of the concrete skeleton.Comparatively,the potential of carbon storage in the bubble of CFC was small.In this study,carbon storage capacity was divided into three categories,i.e.,theoretical maximum capacity,relative reliable capacity,and expected capacity or potential.The carbonation rate for theoretical maximum capacity was 100%,when all the concrete was considered to be carbonated.As the carbonation rate of concrete during the whole life cycle is approximately 55%all over the world,50%was set as the carbonation rate for relative reliable capacity calculation.If at high temperatures,CO_(2) curing with high pressure or accessory ingredients applied to silicate concrete can improve carbonation rate to be over 80%,when the carbon storage capacity is considered to be expected capacity or potential.In 2017⁃2021,the theoretical maximum capacity of carbon storage was 3.623×10^(9) t CO_(2) in China,with 7.25×10^(8) t·a^(-1).The relative reliable capacity was 3.75×10^(8) t·a^(-1),and the expected capacity was 5.80×10^(8) t·a^(-1).If the carbonation rate was 30%,the carbon storage of concrete produced annually in China during the whole life cycle reached 2.18×10^(8) t,which was more than the carbon sink of Daxing'anling forest for one year.In coal electricity integrated mining areas and large thermal,metallurgical,cement chemical,and other high⁃energy consuming enterprises,CFC has a good prospect of development to promote the recycling of solid waste and waste gas.Meanwhile,it is pointed out that the stability of CFC before solidification is a technical problem to be solved in the next step.