Analysis of CO2 hydrate formation from flue gas mixtures in a bubble column reactor
Analysis of CO2 hydrate formation from flue gas mixtures in a bubble column reactor
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DOI：
10.1016/j.seppur.2023.125261
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发表时间：
2023-10
影响因子：
8.6
通讯作者：
Awan Bhati;Aritra Kar;V. Bahadur
中科院分区：
文献类型：
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作者：
Awan Bhati;Aritra Kar;V. Bahadur
千兆级碳捕获与封存（CCS）越来越被视为实现《巴黎协定》目标的关键。作为传统CCS方法的替代方案，二氧化碳水合物作为一种能够实现碳捕获和碳封存新方法的材料而受到关注。二氧化碳水合物（由二氧化碳和水组成的冰状物质）在中压（< 400psi）和温度（bb0 ~ 0°C）下由水-二氧化碳混合物形成。气泡塔反应器（BCR）作为一种较好的co2水合物生成方式已被研究。本研究使用最近开发的内部建模框架来预测BCR在烟气（CO2/N2）和纯CO2流中形成CO2水合物的性能。我们强调并分析了水合物形成的具体方面，这些方面对二氧化碳的封存和二氧化碳的分离/捕获很重要。特别地，分析了两个性能参数：i)水合物形成的气体消耗率（与反应器体积归一化），以及ii)单道中转化为co2水合物的co2分数（转换因子）。第一个指标通过获得可被隔离或从烟道气流中分离的净二氧化碳量来量化BCR的总体生产率。第二个指标与系统的效率有关，通过量化再循环的需求和单次通过后出口流的质量。通过广泛的参数分析，研究了压力、温度、进口co2摩尔分数、气体流速和反应器几何形状对水合物形成的影响。在本研究进行的模拟范围内，单位反应堆体积的最高气体消耗率为28.9吨/年/立方米，最高转换系数为67.8%。这两个参数都随着压力的增加、温度的降低和进口CO2摩尔分数的增加而增加。增加气体流量增加了气体消耗率（即水合物形成率），但降低了转化系数。这表明bcr的整体产能随着气体流量的增加而增加，但以牺牲其效率为代价。效率降低会增加与再循环相关的成本，高流速会增加压缩和冷却成本。对于烟气，通过增加高度或直径来增加反应器体积，可以增加转换系数，但显著降低单位反应器体积的气体消耗率。对于纯CO2，在不改变体积气体消耗率的情况下，增加反应器高度可提高转换系数。在不改变转换系数的情况下，减小直径可提高体积气体消耗率。这些发现表明，紧凑型反应器更适合于co2水合物浆料的生产（以体积为基础），而较大的反应器则适合于co2分离/捕获应用。总体而言，本研究为基于二氧化碳水合物的CCS应用中bcr的设计和运行提供了依据。
Gigascale carbon capture and sequestration (CCS) is increasingly seen as essential to meeting the targets of the Paris Agreement. As an alternative to conventional CCS approaches, carbon dioxide (CO2) hydrates have received attention as materials which can enable new approaches to carbon capture as well as carbon sequestration. CO2hydrates (ice-like materials of CO2and water) form at medium pressures (<400 psi) and temperatures of >0 °C from a water-CO2mixture. Bubble column reactors (BCR) have been studied as a preferred way of forming CO2hydrates. This study uses an inhouse, recently-developed modeling framework to predict performance of a BCR for CO2hydrate formation from flue gas (CO2/N2), and pure CO2streams. We highlight and analyze specific aspects of hydrate formation that are important for CO2sequestration, and for CO2separation/capture. In particular, two performance parameters are analyzed: i) gas consumption rate for hydrate formation (normalized with reactor volume), and ii) fraction of CO2that converts to CO2hydrates in a single pass (conversion factor). The first metric quantifies the overall productivity of a BCR by obtaining the net CO2that can be sequestered or separated from the flue gas stream. The second metric relates to the efficiency of the system by quantifying the need for recirculation and the quality of the exit stream after a single pass. Extensive parametric analysis is conducted to study the influence of pressure, temperature, CO2mole fraction at inlet, gas flow rate and reactor geometry on hydrate formation. Across the range of simulations conducted in this study, the highest gas consumption rate per unit reactor volume was 28.9 ton/yr/m3and the highest conversion factor was 67.8 %. Both parameters increase with increasing pressure, decreasing temperature and increasing inlet mole fraction of CO2. Increasing gas flow rate increases the gas consumption rate (i.e., hydrate formation rate) but reduces the conversion factor. This suggests that the overall productivity of BCRs increases with gas flow rate at the expense of its efficiency. Reduced efficiency increases recirculation-related costs and high flow rate increases compression and cooling costs. For flue gas, increasing the reactor volume by increasing the height or diameter increases conversion factor but significantly reduces the gas consumption rate per unit reactor volume. For pure CO2, increasing the reactor height increases the conversion factor without changing the volumetric gas consumption rate. Decreasing the diameter increases volumetric gas consumption rate without changing the conversion factor. These findings suggest that compact reactors are more suitable for CO2hydrate slurry production (on a volumetric basis), while larger reactors are suitable for CO2separation/capture applications. Overall, this study provides a basis for the design and operation of BCRs for CO2hydrates-based CCS applications.