Abstract:

The annual global CO₂ emission is about 34 billion tons，and energy conservation and carbon reduction in the entire industrial field has become a development trend under the background of “double carbon”. In this paper，the fixation of CO₂ is combined with the chemical crystallization and granulation fluidized bed water treatment system，and CO₂ is used as softening agent together with NaOH for the softening treatment of high-hardness water. The pilot test will be carried out on the dosage and proportion of the chemical，the change of the system’s rising load，and the comparison with the existing treatment methods. The test results show that this method can achieve good softening effect，in which the removal rate of Ca²⁺ can reach up to 89%，and the removal rate of total hardness can reach up to 85%. The dosage of NaOH has a major influence on the softening effect. Therefore，the pH and carbonate content of the softened effluent can be flexibly controlled by controlling the dosage of CO₂，eliminating the need for the subsequent pH adjustment process of the softened effluent and improving the water quality stability. The results of the rising load change test show that the method can still obtain a good softening effect under the condition of 110 m/h，and has a good impact load resistance. Compared with the currently used “dual-alkali method”（adding NaOH and Na₂CO₃ at the same time），this method has low total dosage of alkaline chemicals，low cost per ton of water treatment chemicals，and good economic and ecological benefits. To sum up，CO₂ and NaOH are used as softeners in chemical crystallization and granulation fluidized bed system for water softening，which can be used as a new technology for CO₂ fixation and has certain application potential.

Key words: carbon neutralization, carbon peaking, chemical crystallization circulating granulation fluidized bed, water softening treatment, CO₂ fixation

摘要：

全球CO₂年排放量约为340亿t，工业领域的节能降碳已经成为“双碳”背景下的工业企业发展趋势。将CO₂固定与化学结晶造粒流化床水处理系统相结合，把CO₂作为软化药剂与NaOH共同用于高硬度水质的软化处理。考察药剂投加量及药剂投加浓度比、系统上升流速变化并与现有的处理方法进行对比。结果表明，该方法可以获得良好的软化效果，其中Ca²⁺去除率最高可达到89%，总硬度去除率最高可达到85%。NaOH投加量对软化效率起主要影响作用，因此可以通过控制CO₂投加量灵活控制软化出水pH和碳酸盐浓度，免去了软化出水后续的pH调节工艺，同时提升了水质稳定性。上升流速变化试验结果表明，上升流速为110 m/h的条件下该方法仍可获得良好的软化效果，具有良好的抗冲击负荷能力。与目前所使用的“双碱法”（NaOH和Na₂CO₃作为软化药剂）相比，该方法碱性药剂投加总量低，吨水处理药剂成本低，具有良好的经济效益和生态效益。将CO₂作为软化剂应用于化学结晶造粒流化床系统可作为一种CO₂固定的新技术，具有较大的推广应用潜力。

关键词: 碳中和, 碳达峰, 化学结晶循环造粒流化床, 水质软化处理, CO₂固定

CLC Number: 

• X703.1