摘 要

我国的一次能源消费结构特点是“富煤、贫油、少气”，这决定了我国在较长时间内会消耗大量的煤炭资源，进而导致二氧化碳(CO₂)排放量较高，加剧了温室效应，减少CO₂排放已经成为我国社会关注的重点。利用钙基吸附剂的碳酸化/煅烧循环反应，实现连续捕捉燃煤电站尾气中的CO₂，是一种极具发展潜力的CO₂捕集技术之一。但是，天然石灰石钙基吸附剂在多次碳酸化/煅烧循环反应过程中，比表面积与孔隙率会不断减小，造成严重的烧结现象，使得吸附的CO₂捕集能力大幅度降低，因此非常有必要采用适当的方法提高钙基吸附剂的CO₂捕集能力。

为了增强钙基吸附剂的CO₂捕集能力，本文采用煅烧-水合-浸渍的新方法，制备了碱金属盐修饰改性钙基吸附剂。采用固定床反应器研究了碱金属盐改性钙基吸附剂的碳酸化-煅烧循环反应性能，利用电子扫描显微镜对吸附剂的微观形态结构进行了研究分析。在第20次循环时，采用煅烧-水合-浸渍法，掺杂质量分数为2.0%NaCl的改性吸附剂，其CO₂捕集容积约为天然石灰石的2倍。通过电子扫描显微镜发现，钠盐修饰改性的吸附剂在经过20次循环后，其微观结构呈现不规则团块状，具有较多的大孔结构，这样的多孔结构有助于钙基吸附剂保持较高的反应活性。

此外，本文利用全生命周期评价的方法对钾钠盐修饰改性钙基吸附剂与天然石灰石的CO₂捕集特性进行了经济性分析，定量分析了改性钙基吸附剂制备使用过程中的等效CO₂排放量。结果发现，在经过20次循环后，掺杂质量分数为2.0%NaCl的改性吸附剂的CO₂总吸收量是天然石灰石的1.56倍，CO₂净排放是天然石灰石的1.98倍。

关键词：碳捕集；钙基吸附剂的改性；钾钠盐；全生命周期评价

Abstract

China's primary energy consumption structure is characterized by "rich coal, poor oil and little gas", which determines that China will consume a large number of coal resources in a relatively long period of time, leading to a significant increase in the amount of carbon dioxide emissions (CO₂); Carbon dioxide emissions will further aggravate the greenhouse effect. Reducing CO₂ emission has become the focus of social concern in China. It is one of the most promising CO₂ capture technologies to continuously capture CO₂ from the tail gas of coal-fired power stations by means of calcium based adsorption carbonation/calcination cycle reaction. However, the specific surface area and porosity of natural limestone calcium-based adsorbents will decrease continuously in the process of multiple carbonation/calcination cycles, resulting in serious sintering phenomenon, which greatly reduces the adsorbed CO₂ capture capacity. Therefore, it is very necessary to adopt appropriate methods to improve the CO₂ capture capacity of calcium-based adsorbents.

In order to enhance the CO₂ capture capacity of calcium - based adsorbents, calcium - based adsorbents modified by alkali metal salts were prepared by a new calcination-hydration-impregnation method. The carbonatation-calcination cycle properties of calcium based adsorbents modified by alkali metal salts were studied in fixed bed reactor. The microstructure of adsorbent was studied and analyzed by scanning electron microscope. In the 20th cycle, the carbon capture efficiency of the modified adsorbent with a doping mass fraction of 2.0%NaCl was about twice that of natural limestone by calcination - hydration - immersion method. It was found by sem that after 20 cycles, the microstructure of the sodium modified adsorbent was irregular and massive with more macroporous structures, which helped the calcium adsorbent to maintain high reactivity.

In addition, the economic analysis of the modified calcium-based adsorbent with potassium sodium salt and natural limestone was carried out by the method of full life cycle Analysis. The equivalent CO2 emissions in the preparation and use of modified calcium - based adsorbents were quantitatively analyzed. The results showed that after 20 cycles, the total CO2 absorption of the modified adsorbent with a doping mass fraction of 2.0%NaCl was 1.56 times that of the natural limestone, and the net CO2 emission was 1.98 times that of the natural limestone.

Key Words：Carbon capture; Modification of calcium - based adsorbent; Potassium sodium；LCA

目录

摘 要 I

目录 1

第1章 绪论 1

1.1 我国的一次能源结构与碳排放情况 1

1.2 CO₂排放与控制技术 3

1.3 CO₂捕集与封存技术(CCS) 4

1.4 钙基吸附剂的研究进展与现状 5

1.4.1 钙循环碳捕集技术的提出与发展 5

1.4.2 关于钙基吸附剂的循环碳酸化/煅烧特性的研究 8

1.4.3 关于钙基吸附剂改性的研究 9

1.5 关于碱金属盐改性钙基吸附剂的研究 10

1.5.1 在FBC/TGA中掺杂钠盐改性 10

1.5.2 高锰酸钾改性 10

1.5.3 钾钠盐改性的研究与比较 11

第2章 钠盐改性钙基吸附剂的实验研究 12

2.1 相关材料及吸附剂的准备工作 12

2.2 吸附剂测试工作 13

2.3 改性吸附剂的实验结果与分析 13

2.3.1 关于改性吸附剂对CO₂吸收性能的分析 13

2.3.2 关于吸附剂在循环反应中微观结构特性分析 17

2.3 本章小结 18

第3章 利用全生命周期评价对于钠盐改性进行分析 20

3.1 研究对象及范围的确定 20

3.2 全生命周期清单分析 21

3.3 全生命周期影响的计算分析与评价 23

3.4 全生命周期解释 28

3.5 本章小结 28

第4章 结论 29

参考文献 29

致谢 31

第1章 绪论

1.1 我国的一次能源结构与碳排放情况

根据国际能源署(IEA)发布的数据^[1]，1990-2017年我国的的一次能源总供应量(TPES)如下图1.1所示(堆积百分比形式)

图1.1 我国按来源划分的一次能源总供应量(1990-2017)

图1.2 2017年我国一次能源消费结构图

截止到2017年，我国一次能源结构分布如上图1.2所示，其中煤炭消费占能源消费总量的60.4%。通过借助以上两个图表可以清晰的了解到，我国一次能源的长期基本特点是“富煤、贫油、少气”，尽管在近些年，随着国家对风能，太阳能等的清洁能源的大力投资，煤炭的消费比重略有降低，但是我国的一次能源结构分布决定了我国在较长时间内依旧会把煤炭作为主要的一次能源消费对象。而煤炭等化石燃料的大规模使用则会产生大量的碳排放。

图1.3 我国按能源划分的CO₂排放量