Cryogenic separation of CO₂ is a potential technology that can benefit from energy efficiency improvements. However, the current conventional and emerging cryogenic technologies face challenges in terms of high utility consumption. The high utility requirement leads to increasing operational costs and emissions due to the production of required utilities from external energy sources. This issue can be solved if the heat recovery potential of the technology can be realized. Heat recovery enables further improvement in energy efficiency that is required to elevate the feasibility of cryogenic separation. This paper explores heat recovery opportunities between hot and cold streams in a novel cryogenic CO₂ capture technology known as Turbo-Expander-based Cryogenic Distillation (CryoDT). This is achieved using P-HENS, a P-graph-based heat exchanger network synthesis tool where multiple feasible heat exchanger network configurations are generated to determine the options that effectively recover process heat to reduce utility consumption. Moreover, the solutions generated by P-HENS are benchmarked with other tools like Aspen Energy Analyzer, by comparing the number of required heat exchangers, along with the associated capital and operating costs. For the predefined hot and cold process streams of the novel technology, the total number of heat exchangers present in the network was lower in the recommended design using P-HENS (i.e., 9 heat exchangers) as opposed to Aspen Energy Analyzer (16 heat exchangers) while maintaining similar energy consumption levels. This indicates that there is a further opportunity to reduce capital costs as a result of less heat exchangers. The CryoDT configuration that is integrated with a heat exchanger network offers significant economic advantages as opposed to other existing cryogenic processes in the market such as the Ryan Holmes and Controlled Freeze Zone (CFZ) processes. Despite its high capital cost, the CryoDT process demonstrates significantly lower operating cost relative to the other two processes. Hence, while the initial investment is substantial, the CryoDT process is much more cost efficient to operate. The low operating cost is attributed to its higher energy efficiency and minimal energy penalties, with only 0.26 GJ/tonne of CO₂ compared with 0.82 GJ/tonne of CO₂ for the CFZ process and 2.33 GJ/tonne of CO₂ for Ryan Holmes. In contrast, the Ryan Holmes process, despite its low capital cost, incurs extremely high annual operational costs, rendering it less economic in the long term. The CFZ process, with its moderate operating cost, presents a balance between capital cost and operational efficiency.

中文翻译：

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用于基于涡轮膨胀机的低温 CO2 捕获技术的多溶液换热器网络合成


CO₂ 的低温分离是一种潜在的技术，可以从能源效率的提高中受益。然而，当前传统和新兴的低温技术面临着高公用事业消耗方面的挑战。由于从外部能源生产所需的公用设施，高公用事业要求导致运营成本和排放增加。如果能够实现该技术的热回收潜力，这个问题就可以得到解决。热回收可以进一步提高能源效率，这是提高低温分离可行性所必需的。本文探讨了一种新型低温 CO₂ 捕获技术（称为基于 Turbo-Expander 的低温蒸馏 （CryoDT））中热流和冷流之间的热回收机会。这是使用 P-HENS 实现的，P-HENS 是一种基于 P 图的换热器网络合成工具，其中生成多个可行的换热器网络配置，以确定有效回收工艺热量以减少公用事业消耗的选项。此外，P-HENS 生成的解决方案与 Aspen Energy Analyzer 等其他工具进行了基准测试，通过比较所需热交换器的数量以及相关的资本和运营成本。对于新技术的预定义热和冷工艺流，在使用 P-HENS（即 9 个换热器）的推荐设计中，与 Aspen Energy Analyzer（16 个换热器）相比，网络中存在的换热器总数较低，同时保持相似的能耗水平。这表明，由于换热器的减少，还有进一步降低资本成本的机会。 与市场上其他现有的低温工艺（如 Ryan Holmes 和受控冻结区 （CFZ） 工艺）相比，与热交换器网络集成的 CryoDT 配置具有显著的经济优势。尽管资本成本高，但与其他两种工艺相比，CryoDT 工艺的运营成本显著降低。因此，虽然初始投资很大，但 CryoDT 工艺的运行成本要高得多。低运营成本归因于其更高的能源效率和最小的能源损失，只有 0.26 GJ/吨 CO₂，而 CFZ 工艺的 CO₂ 为 0.82 GJ/吨，Ryan Holmes 为 2.33 GJ/吨 CO₂。相比之下，Ryan Holmes 工艺尽管资本成本低，但每年的运营成本极高，从长远来看，其经济性较低。CFZ 工艺具有适中的运营成本，在资本成本和运营效率之间实现了平衡。