(17b) Heat Integration and Optimization of Low-Temperature Carbon Dioxide (CO2) Removal Via Distillation

Pinch analysis is one of the ways that the chemical process industry uses to optimize the process. In the low-temperature process industry, such as gas and liquid natural gas processes, heat integration is crucial to address the abundance of energy requirements by the process to meet the product specification. Current natural gas resources with low acid gas contaminants such as carbon dioxide (CO₂) is depleting. Hence, the exploration to monetize on a high CO₂ gas field was initiated. Low-temperature distillation for separation of bulk CO₂ to the acceptable specification was selected as one of the CO₂ capture technologies. However, the energy required for such application is relatively large. Therefore, a pinch analysis in the pilot design of the technology was conducted to evaluate the potential energy saving by employing the heat integration analysis. The Pinch Analysis technique uses a parameter called DT_min to establish the minimum theoretical energy requirements of the system. The process scheme was constructed using Aspen Hysys to determine the actual hot and cold utility load. Then, hot and cold streams and properties will be extracted into Aspen Energy Analyzer (AEA) to perform optimal heat exchanger network design. The pinch analysis and Heat Exchanger Network (HEN) results show 25% to 85% utility saving for hot and cold streams. Based on the existing process configuration, the calculated DT_min is greater than 5^oC, but in this study, DT_min at 3°C is used to optimize the process and established a new HEN. Thus, the new HEN's retrofit design was incorporated to improve the hot and cold utilities target further.