Development of a Rigorous Modeling Framework for Solvent-Based CO₂ Capture. 1. Hydraulic and Mass Transfer Models and Their Uncertainty Quantification

Abstract

Rigorous process models are critical for reducing the risk and uncertainty of scaling up a new technology. It is essential to quantify uncertainty in key submodels so that uncertainty in the overall model can be appropriately characterized. In solvent-based postcombustion CO2 capture technologies, mass transfer and column hydraulics are key factors affecting the performance of the absorber. Developing submodels for mass transfer, column hydraulics, and reactions is a challenging multiscale problem since the phenomena are tightly coupled and it is difficult to design experiments to isolate each properly. In particular, simultaneous mass transfer coupled with fast reaction kinetics makes it difficult to measure the mass transfer rate and reactions rate individually. The typical approach to solving this issue is to use proxy systems to conduct experiments under mass-transfer-limited or reaction-limited conditions. This approach can lead to inaccurate mass transfer submodels. In this paper, a novel simultaneous regression approach is proposed where submodels for mass transfer, diffusivity, interfacial area, and reaction kinetics are optimally identified using experimental data from multiple scales and operating conditions. Since all models have some level of uncertainty, a rigorous uncertainty quantification (UQ) technique is implemented for the hydraulic and mass transfer submodels based on Bayesian inference. Posterior distributions of submodel parameters are propagated through the column model to obtain the uncertainty bounds on critical performance measures.

Towards improved guidelines for cost evaluation of carbon capture and storage

“…Like with any probabilistic method however, they are best suited for the variability of input parameters, and less for real uncertainty, given that there may not be a reasonable basis for probability density functions of truly uncertain parameters. [188][189][190] in which surrogate models of an MEA capture plant were built based on a full process model and compared with process data from the National Carbon Capture Center (NCCC) in Alabama, USA [191]. Table 3-5 shows the names of the varied parameters along with sources that contain more details of the sub-model development and uncertainty quantification.…”

“…The SDoE methodology requires an initial process model, or a reduced-order surrogate model of the process, in which some of the parameters are characterized by probability density functions (PDFs), representing the parametric uncertainty. For the example of a solvent-based carbon capture system, uncertain parameters may include those related to the physical properties the system, reaction kinetics, and mass transfer and hydraulic models for the packing used in absorption and stripping columns [188][189][190]. Accurate characterization of mass transfer, interfacial area, and hydraulics, with quantified uncertainty, is necessary for representing the rate-based column models with a specific packing type.…”

Rate-Based Absorption Modeling for Postcombustion CO2 Capture with Additively Manufactured Structured Packing

“…The mass transfer coefficients and interfacial area correlations used in the model here are derived from recent work by Rochelle and co-workers studying structured packing. − A benefit of these recent correlations is the reliance on only the geometric properties of the structured packing to estimate the effective interfacial area and mass transfer coefficients. Other correlations exist that have shown to be accurate but require measurements to determine packing-specific constants. ,, As the mass transfer coefficients for additively manufactured packing have not yet been determined, the correlations from Rochelle allow estimation of structured packing mass transfer properties for developing a deterministic absorption model. While other correlations for random, dumped packings exist for predicting mass transfer, only structured packing correlations are considered here in validating the modeling framework as the intensified device is composed of structured packing material for mass transfer.…”

“…Other correlations exist that have shown to be accurate but require measurements to determine packing-specific constants. 17,48,49 As the mass transfer coefficients for additively manufactured packing have not yet been determined, the correlations from Rochelle allow estimation of structured packing mass transfer properties for developing a deterministic absorption model. While other correlations for random, dumped packings exist for predicting mass transfer, only structured packing correlations are considered here in validating the modeling framework as the intensified device is composed of structured packing material for mass transfer.…”

“…Absorption utilizing amine chemistry to react CO 2 with the solvent has been investigated to demonstrate the capability of benchmark and novel solvents to scrub CO 2 from flue gas streams. − As absorption technology requires the regeneration of the solvent within a stripping column, research has focused on means of reducing the parasitic energy and capital investment of an amine-based process through innovative process configurations, solvent formulations, and their combinations. ,− This has led to studies of commercially available solvents, such as aqueous monoethanolamine (MEA), as well as the development of more advanced solvents, including novel amines, organic-based solvents, and ionic liquids. ,− A common difficulty in amine-based solvents for CO 2 capture is the management of the exothermic energy generated within the absorption column due to the reaction between CO 2 and the amine. ,, This phenomenon requires balance between the reaction kinetics, CO 2 solubility, and process design. Using aqueous MEA, there may be large temperature increases in the absorption column from absorption of CO 2 , and utilization of heat exchangers between packed bed stages within an absorption column may be required to manage the exothermic reaction. ,, …”