Integrated Ionic Liquid and Absorption Process Design for Carbon
Capture: Global Optimization Using Hybrid Models
Abstract
A new method for integrated ionic liquid (IL) and absorption process
design is proposed where a rigorous rate-based process model is used to
incorporate absorption thermodynamics and kinetics. Different types of
models including group contribution models and thermodynamic models are
employed to predict the process-relevant physical, kinetic, and
thermodynamic (gas solubility) properties of ILs. Combining the property
models with process models, the integrated IL and process design problem
is formulated as an MINLP optimization problem. Unfortunately, due to
the model complexity, the problem is prone to convergence failure. To
lower the computational difficulty, tractable surrogate models are used
to replace the complex thermodynamic models while maintaining the
prediction accuracy. This provides an opportunity to find the global
optimum for the integrated design problem. A pre-combustion carbon
capture case study is provided to demonstrate the applicability of the
method. The obtained global optimum saves 14.8% cost compared to the
Selexol process.