Process Intensification for Post-combustion Carbon Capture using Rotating Packed Bed through Systems Engineering Techniques

二氧化碳排放到大气中引起了全世界的巨大关注，特别是因为人们普遍认为大气中二氧化碳浓度的增加是气候变化的关键驱动因素。如果目前二氧化碳排放的趋势继续下去，预计全球气温将上升4摄氏度以上，这对世界来说将是灾难性的。随着世界人口的增加，能源需求也在不断增加。尽管可再生能源的份额正在增加，但在可预见的未来，燃煤和燃气发电厂在满足这种能源需求方面仍将发挥核心作用。这些发电厂是二氧化碳最大的固定来源。碳捕获是一种捕获这些发电厂在烟气中排放的二氧化碳的技术。该提案旨在对用于碳捕获的方法进行重大改进，以降低总成本。利用溶剂（如单乙醇胺- MEA）的化学吸收法捕获燃烧后的二氧化碳是最成熟的技术之一。传统技术使用大型填充柱。目前，为发电厂建造和运行捕集装置的成本非常高，因为：(1)填料柱的尺寸非常大；(2)再生溶剂再循环所消耗的蒸汽量很大。如果我们能够设法减少填料塔的尺寸和蒸汽消耗，那么碳捕获的成本将相应降低。从我们以前的研究中，我们发现用于碳捕获的传统填料柱的传质非常差。这项研究有望在传质方面取得重大进展。关键思想是旋转填料柱，使其每分钟旋转数百次，即所谓的旋转填料床（RPB）。由于接触面积较大，在RPB内部会产生更好的传质效果。通过强化捕获过程，可以使用更高浓度的溶剂（例如70 wt% MEA），强化吸收塔和汽提塔之间的再循环溶剂量将减少到40%左右。我们的初步分析已发表在国际领先的杂志上，它表明，在一个RPB填料体积将小于10%的等效传统填料柱。该提案将研究如何设计和操作RPB，以便最有效地从烟气中分离二氧化碳。这项工作将包括设计新的实验设备、实验研究、过程建模和模拟、系统集成、强化吸收器和汽提器的放大、过程优化、从技术、经济和环境的角度比较强化捕集过程和传统捕集过程。该研究将包括对强化吸收器中溶剂和烟气流的最佳流动方向（平行流动或逆流）以及RPB内填料的最佳设计进行研究。该提案还将比较CCGT发电厂使用过程强化与使用传统填料塔的整个系统性能。在此基础上，将进行经济分析，以量化这种新的过程强化技术所提供的节省。

The emission of carbon dioxide into the atmosphere has caused huge concerns around the world, in particular because it is widely believed that the increase in its concentration in the atmosphere is a key driver of climate change. If the current trend in the release of carbon dioxide continues, global temperatures are predicted to increase by more than 4 degrees centigrade, which would be disastrous for the world.With the increase in world population, the energy demand is also increasing. Coal-fired and gas-fired power plants still play a central role in meeting this energy demand for the foreseeable future, even though the share of renewable energy is increasing. These power plants are the largest stationary sources of carbon dioxide. Carbon capture is a technique to capture the carbon dioxide that is emitted in the flue gas from these power plants. This proposal seeks to make a significant improvement in the methods used for carbon capture in order to reduce the total costs. Post-combustion CO2 capture by chemical absorption using solvents (for example, monoethanolamine - MEA) is one of the most mature technologies. The conventional technology uses large packed columns. The cost to build and run the capture plants for power plants is currently very high because: (1) the packed columns are very large in size; (2) the amount of steam consumed to regenerate solvents for recirculation is significant. If we can manage to reduce the size of packed columns and the steam consumption, then the cost of carbon capture will be reduced correspondingly.From our previous studies, we found that mass transfer in the conventional packed columns used for carbon capture is very poor. This proposed research is expected to make very significant improvements in mass transfer. The key idea is to rotate the packed column so that it spins at hundreds of times per minute - a so-called rotating packed bed (RPB). A better mass transfer will be generated inside the RPB due to higher contact area. With an intensified capture process, a higher concentration of solvent can be used (for example 70 wt% MEA) and the quantity of recirculating solvent between intensified absorber and stripper will be reduced to around 40%. Our initial analysis has been published in an international leading journal and it indicates that the packing volume in an RPB will be less than 10% of an equivalent conventional packed column.This proposal will investigate how to design and operate the RPB in order to separate carbon dioxide most efficiently from flue gas. The work will include design of new experimental rigs, experimental study, process modelling and simulation, system integration, scale-up of intensified absorber and stripper, process optimisation, comparison between intensified capture process and conventional capture process from technical, economical and environmental points of view. The research will include an investigation into the optimum flow directions for the solvent and flue gas stream (parallel flow or counter-current) for intensified absorber and the optimum design of packing inside the RPB.The proposal will also compare the whole system performance using process intensification vs using conventional packed column for a CCGT power plant. Based on this, an economic analysis will be carried out to quantify the savings provided by this new process intensification technology.