Carbon Capture in the Refining Process (First Grant Scheme)

在炼油厂，二氧化碳有两个不同的来源——首先是热电联产锅炉的燃料燃烧（约占二氧化碳总排放量的35%），以及过程加热器/炉（约占45%），其次是H2装置（约占20%）。锅炉/加热器/炉内的燃料燃烧被确定为精炼过程中二氧化碳排放的主要来源，约占二氧化碳总排放量的80%。然而，燃料燃烧的CO2源广泛分布在整个综合设施中，其烟气中的CO2摩尔分数相对较低（4-15%）。因此，在这些资源上部署和运行碳捕集装置会导致大量的资本投资和运行成本，以及操作难度。与燃料燃烧产生的二氧化碳排放不同，氢气厂的二氧化碳排放的特点是单一来源的二氧化碳浓度很高（50-60%），这意味着从氢气厂捕获二氧化碳比从其他来源捕获二氧化碳更有效。拟议的研究旨在开发一种真空摆动吸附（VSA）工艺，以捕获精炼过程中氢气厂产生的二氧化碳。对于燃烧后的捕集，胺法迄今为止最接近商业化，并已准备好部署，但在这种特殊情况下，由于饲料中的二氧化碳含量较高，循环吸附法可能比胺法更节能。此外，应该强调的是，作为现有H2 PSA工艺的补充，CO2 VSA装置具有操作灵活性，因为它可以在各种模式下运行，包括捕获模式、非捕获模式或控制负载捕获模式。该研究将侧重于寻找基于商业吸附剂的CO2 VSA工艺的最佳配置。目标是从H2 PSA废气中获得90%以上的二氧化碳回收率和95%以上的纯度。将构建一个实验室规模的多柱VSA平台，以证明通过精心设计的循环吸附过程可以实现目标。VSA流程的设计和优化将通过与钻机操作并行的适当模拟工作来促进。为了优化其蒸汽网络，将实施与VSA工艺集成的示例H2装置的整体工艺设计。

In the refinery, CO2 comes from two different sources - firstly by fuel combustion in the CHP boiler (around 35% of total CO2 emission), and process heater/furnace (around 45%), and secondly from the H2 plant (around 20%). The fuel combustion in the boiler/heater/furnace is identified as major source of CO2 emission in the refining process accounting for around 80% of total CO2 emission. However, the CO2 sources by fuel combustion are widely distributed throughout the complex and their flue gas has relatively low CO2 mole fraction (4-15%). Therefore, deploying and operating carbon capture units to these sources result in significant capital investment and running cost as well as operational difficulty. Unlike the CO2 emissions by fuel combustion, the CO2 emissions from the H2 plant are characterised by a single source having highly concentrated CO2 (50-60%), which implies that it would be more efficient to capture CO2 from the H2 plant than from the other sources. The proposed research aims to develop a Vacuum Swing Adsorption(VSA) process to capture CO2 from a H2 plant in the refining process. For post-combustion capture, the amine process is, to date, closest to commercialisation and ready to be deployed, but a cyclic adsorption process can be more energy-efficient than the amine process in this particular case due to a high CO2 fraction in the feed. Moreover, it should be emphasised that the CO2 VSA unit supplementary to an existing H2 PSA process has operational flexibility, as it can be operated in various modes, including capture-mode, non-capture mode or controlled-load capture mode.The research will focus on finding an optimal configuration for the CO2 VSA process based on a commercial adsorbent. The target is to achieve 90+% CO2 recovery with 95+% purity from the H2 PSA off-gas. A lab-scale multi-column VSA rig will be constructed to demonstrate that the target can be achieved by a well-designed cyclic adsorption process. The design and optimisation of the VSA process will be facilitated by a proper simulation work in parallel with operation of the rig. An overall process design of an example H2 plant integrated with the VSA process will be implemented for the purpose of optimising its steam network.