Optimized adsorption processes for CO2 capture

加拿大政府将工业烟气中的碳捕集与封存（CCS）确定为减少二氧化碳排放的重要技术。例如，一个500兆瓦的燃煤电厂每天产生大约16000吨二氧化碳。利用现有技术，例如胺基吸收技术，从稀释的烟气流中捕获二氧化碳（二氧化碳成分为12 -15%）并将其浓缩至高纯度（100 - 90%），成本高昂，需要开发替代品。固体吸附剂吸附已被确定为一种有前途的选择。二氧化碳吸附捕集的主要挑战是：1。新型吸附剂的开发；2. 设计和优化新工艺配置（周期），以达到纯度和回收率bbb90 %的监管目标；和3。实验演示（使用湿烟气）和成本估算，与其他技术进行比较。本提案为挑战1开发了启用工具，并为挑战2和3开发了解决方案。该研究计划提出了两个项目。这些项目的独特之处在于，它们将实验和建模方法相结合，以找到实际的CCS解决方案。项目1：从湿烟气中捕集二氧化碳：大多数关于吸附式二氧化碳捕集的报告都考虑了干燥的烟气原料。然而，工业烟气中饱和的水分（12.5 mol%）会对大多数吸附剂的CO2吸附能力产生不利影响。令人惊讶的是，人们对H2O对吸附式CO2捕获的影响的理解没有给予足够的重视。项目1将研究高浓度下吸附的基本原理，开发湿法烟气二氧化碳捕获工艺，并量化所涉及的成本。项目2：合理的工艺设计和吸附剂选择：吸附过程有两个重要组成部分：循环和吸附剂。吸附循环的设计是基于过去的经验和有限的模拟+实验。这种方法既不能保证流程被优化，也不能保证所有可能的配置都被探索过。在材料方面，新型添加剂如金属有机框架（mof）呈爆炸式增长。许多性能指标，通常基于平衡信息，已经提出了选择正确的吸附剂为特定的应用。由于吸附是一个相当复杂的操作，涉及同时传热/传质，以及复杂的配置，我们最近表明，这些指标与工艺性能无关，使用它们是相当误导的。项目2将通过开发基于上部结构的优化技术来解决这些挑战，该技术将自动合成复杂的吸附循环；优化他们的操作条件，并选择最佳的工艺+吸附剂组合为特定的分离。这里概述的研究计划不仅适用于CO2捕集，还适用于其他重要的气体分离，天然气和页岩气净化，例如CO2/CH4， CH4/N2分离和碳氢化合物分离。所有这些分离对阿尔伯塔省和加拿大的经济至关重要；每一个都代表着一笔数百万美元的生意。培养博士生2名，本科生4名。参与该项目的HQP将接受结合实验和数学建模的培训，这是一种相当罕见的结合。他们还将获得设计、建造和调试多柱压力/真空摆动吸附系统的独特机会。HQP将接受分离流程设计和优化、化工流程设计和较强沟通能力的培训；这些特质将使他们在自己选择的职业道路上取得成功。

Carbon capture and storage (CCS) from industrial flue gas is identified by the Canadian government as an important technology to reduce CO2 emissions. For example, a 500 MW coal-based power plant produce ca. 16,000 tonnes of CO2 per day. Capturing CO2 from a dilute flue gas stream (CO2 composition is 12 -15%) and concentrating it to high purities (>90%), using current technologies, e.g., amine-based absorption, is expensive and there is a need to develop alternatives. Adsorption using solid sorbents has been identified as a promising option. The main challenges in adsorptive CO2 capture are: 1. development of novel adsorbents; 2. design and optimization of novel process configurations (cycles) to achieve regulatory targets on purity & recovery > 90%; and 3. experimental demonstration (using wet flue gas) and cost estimation to compare with other technologies. This proposal develops enabling tools for challenge #1 and solutions for #2 & 3. Two projects are proposed under the research program. The distinctive feature of the projects is that they integrate experimental+modelling approaches to find practical CCS solutions. PROJECT 1: CO2 CAPTURE FROM WET FLUE GAS: Most reports on adsorptive CO2 capture have considered a dry flue gas feed. However, industrial flue gas is saturated with moisture (12.5 mol%) which can adversely affect CO2 adsorption capacity of most adsorbents. It is indeed surprising that not enough attention has been paid to the understanding of the effect of H2O on adsorptive CO2 capture. Project 1 will study the fundamentals of adsorption under high H2O concentrations and develop processes for wet flue-gas CO2 capture and quantify the costs involved. PROJECT 2: RATIONAL PROCESS DESIGN & ADSORBENT SELECTION: Adsorption processes have two important constituents: the cycle and the adsorbent. Adsorption cycles are designed based on past experience and limited simulations+experiments. This approach neither guarantees that a process is optimized nor that all possible configurations have been explored. On materials front, there has been an explosive growth of new adsrbents, e.g., metal-organic frameworks (MOFs). Many performance metrics, typically based on equilibrium information, have been proposed to select the right adsorbent for a particular application. Since adsorption is a fairly complex operation involving simultaneous heat/mass transfer, together with intricate configurations, we have recently shown that these metrics do not correlate with process performance and using them is rather misleading. Project 2 will address these challenges through the development of superstructure based optimization techniques which will automatically synthesize complex adsorption cycles; optimize their operating conditions and choose the best process+adsorbent combination for a particular separation. The research program outlined here, will not only be applicable to CO2 capture, but also to other important gas separations, natural and shale gas purification e.g., CO2/CH4, CH4/N2 separations and hydrocarbon separations. All these separations are vital to the economy of Alberta and Canada; each representing a business of the order of millions of dollars. Two PhD and four undergraduate students will be trained. HQP involved in this project will receive training that combines both experimentation and mathematical modelling, a rather rare combination. They will also receive an unique opportunity to design, construct and commission a multi-column pressure/vacuum swing adsorption system. HQP will be trained in design and optimization of separation processes, chemical process design and strong communication skills; attributes that will enable them to be successful in their chosen career paths.