(500g) Simultaneous Optimization of Membrane-Cryogenic Hybrid System for CO2 Capture and Separation

Liao, Z., Zhejiang University
You, F., Cornell University
This paper addresses the systematic design and optimization of membrane-cryogenic hybrid separation system for CO2 capture. The design of such hybrid separation system involves synthesis of separation sequences, design of heat exchanger networks and optimization of compression/expansion networks. Each of the sub-systems are complex systems with tight interactions. Therefore, it is challenging to synthesis these subsystems simultaneously. To design this complex hybrid carbon capture process, a novel two-step approach is proposed. The separation sequence, as well as energy consumption are optimized first. Then the heat exchanger network is synthesized with flowsheet optimization simultaneously. Meanwhile, a loop count procedure is introduced to provide more possible solutions. A corresponding feasible solution set is proposed as a bridge between the two steps. In addition, discrete cutting method and piecewise approximation approach are introduced to improve the reliability and validity of the two-step model. Case studies of both pre-combustion and post-combustion carbon capture show that the optimized hybrid system reduced nearly 50% recovery cost. Final results indicate that hybrid system is especially suitable for the post-combustion CO2 capture process.