“Investigating Surface Tension Predictions for High-Pressure Column Modelling: Findings & Recommendations”
Ruan de Villiers
Abstract
The recovery of valuable hydrocarbons from natural gas is accomplished using a series of distillation columns operating under high pressures (e.g. demethanizers). Designing these columns is performed with a rate-based column simulation which requires some information about the sizing, geometry, and internal design of the column. Many published and proprietary property models exist, and the choice of design models can lead to significant differences in the viability of the simulation and the estimated capital cost of the column, so reliable models are of the utmost importance when simulating and designing a distillation column for real-world operation.
One property that appears to have a significant impact on the design and cost of high-pressure columns is the surface tension (ST) of the vapor-liquid system in the column. Though many satisfactory models exist for pure-component STs, none of the mixture ST models commonly available in process simulators perform well across broad ranges of system conditions and choices of mixture. Moreover, many of these models predict extremely low mixture STs (≤ 1 dyn/cm) when applied to high-pressure column design, precisely the conditions under which design is most uncertain. Many of these ST models are unreliable, particularly when the system conditions exceed the pure-component critical point of one or more species in the mixture.
More sophisticated ST models have been developed in recent years, but most of them are not available to the engineers that actually design separation processes commercially. In his thesis proposal, this author outlined a plan to develop and incorporate several modern models, including promising methods such as Density Gradient Theory (DGT), for mixture ST into the freely-available column simulation software ChemSep. This talk will follow up on the progress of those efforts, report on the strengths/limitations of the investigated methods as well as on the quality/applicability of their results, and finally present some tentative “best practice” recommendations for engineers modelling ST at high pressures.
Wednesday, 3/12/2025 at 2:30 pm
CAMP 194
https://clarkson.zoom.us/j/95529580049
Bio:
Ruan de Villiers is a Ph.D. candidate at Clarkson University under Professor Ross Taylor. He earned his B.S. in Chemical Engineering from the University of Texas at Austin in 2020. His former and current work includes simulation of reactive dividing wall columns, thermodynamic phase stability, molecular/Helmholtz-based equations of state (SAFT), and surface tension estimation for the design of high-pressure distillation columns. During the course of his Ph.D., he has presented his research at the 12th International Conference on Distillation & Absorption, DA 2022 in Toulouse, France, and at the AIChE 2023 Spring Meeting in Houston, Texas, as well having published two journal papers and one conference paper.