Due to high global warming potential (GWP) of hydrofluorocarbons (HFCs), the separation and recovery of HFCs from different refrigerant mixtures is an important issue. Most HFC mixtures are azeotropic in nature, thereby rendering the conventional distillation-based separation difficult and energy intensive. Extractive distillation (ED) with ionic liquid (IL) as solvent provides an attractive strategy for selective separation of HFC mixtures. However, systematic design and optimization of ED-based separation processes is nontrivial. In this work, we present SPICE_ED which is a software framework for the detailed design, synthesis, and techno-economic analysis of ED-based separation processes. The framework employs a building block representation followed by superstructure optimization that is able to automatically generate numerous design solutions and screen the best without requiring prior expert knowledge of candidate configurations. For a given IL as solvent and a set of design specifications, one can automatically determine the feasibility of the solvent and obtain the optimal process flowsheets that correspond to minimum energy consumption, minimum separation cost, or minimum emission/waste. We demonstrate the capability of SPICE_ED for the separation of R-410A (50 wt % R-32 and 50 wt % R-125) using [bmim][PF 6 ], a commonly used IL. Our optimized design requires an equivalent work of only 338.2 kJ/kg R-410A, which is about 48% less than the previously reported value of 656 kJ/kg. The newly identified design also achieves more than 47% and 27% reductions in CO 2 -equivalent emission (sustainability) and cost, respectively. Through multiobjective optimization, we further identify an operating regime to separate R-410A at a near-minimum cost without significantly increasing the energy consumption and emission. The processes obtained from SPICE_ED show excellent agreement with the key performance metrics when simulated in Aspen Plus, thereby establishing confidence in our designs as realistic and implementable.
A membrane reactor (MR) combines reaction and separation phenomena in a single unit and offers an energy-efficient, cost-effective, compact, modular, and sustainable design compared to conventional designs. A systematic design framework can yield such benefits of MRs and increase their adoption in the chemical process industry. To this end, we present SPICE_MARS (synthesis and process intensification of chemical enterprises involving membrane-assisted reactive separations), a software prototype for conceptual design, simulation, synthesis, and optimization of MRs for different process applications. At the conceptual level, we can determine whether MR is desired or not and select which species to convert/separate. At the equipment level, we obtain optimal MR configurations considering different flow arrangements, intensification strategies, membrane types, sweep gases, reactor lengths, membrane areas, and catalyst amounts. Additionally, we can generate rank-ordered lists of optimal reactor configurations for different design objectives. These enabling capabilities are demonstrated using two case studies involving methanol synthesis and methane partial oxidation. In both cases, novel MR designsachieving drastic improvement compared to current industrial practiceare found.
The recent revolution in shale gas has presented opportunities for distributed manufacturing of key commodity chemicals, such as methanol, from methane. However, the conventional methane‐to‐methanol process is energy intensive which negatively affects the profitability and sustainability. We report an intensified process configuration that is both economically attractive and environmentally sustainable. This flowsheet is systematically discovered using the building block‐based representation and optimization methodology. The new process configuration utilizes membrane‐assisted reactive separations and can have as much as 190% higher total annual profit compared to a conventional configuration. Additionally, it has 57% less CO2‐equivalent greenhouse gas emission. Such drastic improvement highlights the advantages of building block‐based computer‐aided process intensification method.
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