Ionic liquids (ILs) are a promising class of absorbents for next-generation carbon-capture processes. In particular, aprotic heterocyclic anion ILs (AHAs) have received significant attention due to their ability to chemically absorb CO2 without a significant increase in viscosity. The development of process modeling and mathematical optimization approaches for AHA-based carbon-capture processes is essential for the evaluation of economic feasibility before industrial implementation. In this paper, we use a pseudo-transient modeling approach that enables the robust simulation and optimization of the large-scale process flowsheet. A Langmuir-type model that incorporates both the chemical and physical uptake of CO2 is used to describe the equilibrium absorption of CO2 by the IL. A rigorous rate-based model for the absorption column is employed to account for the effect of reversible chemical reactions on mass transfer. The models are then used to carry out economic optimization of a prototypical IL-based carbon-capture process. A sensitivity analysis of important IL properties is provided, revealing the key factors that affect IL choice. Finally, a comparison to an advanced amine-based process is briefly discussed.

Power systems operations involve dispatching generation capacity and ancillary services as required to sustain reliable functioning of the electric grid. The dispatch schedules are determined by solving power flow calculations that incorporate models of the network components in real time as the power grid conditions change. Electricity intensive chemical processes can potentially provide grid support services and a closer coordination between process and grid operations can be beneficial. This cooperation is hindered by the lack of suitable process models, which appropriately protect process information. We propose a means to model the grid-relevant dynamics of chemical processes, and a framework for embedding such models in optimal power flow calculations. We present an extensive case study concerning cooperative demand-response operation for an electricity-intensive chemical process, chlor-alkali production. The results indicate significant flexibility and economic benefits both at the utility and at the end-user levels.

Aprotic heterocyclic anion ionic liquids (AHA ILs) have received significant recent attention as potential absorbents for next-generation carbon capture processes. In this paper, we describe a rate-based model of an AHA IL-based carbon capture process. We use the model to perform economic optimization, minimizing a total cost function (annual operating cost plus annualized capital cost). Process-level decisions, including equipment design and operating parameters, are considered simultaneously with the material-level decision of the CO2 reactive absorption enthalpy in the AHA IL being a tunable molecular parameter. We study how the optimal design changes with flexible flue gas compositions, with a focus on cases arising in the context of partial oxy-combustion. We also study the variation in the optimal design as the CO2 capture level changes. Flexibility in this regard is important as power plants increasingly need to account for time-varying power demand due to the market penetration of variable renewable energy sources such as wind and solar power.

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