(395e) Improving the Capability of Process Simulators to Represent Solid-Fluid Equilibria Applied to Natural Gas Liquefaction: The Methane + Neopentane System at Low Temperature
AIChE Annual Meeting
Tuesday, November 15, 2022 - 4:42pm to 5:00pm
This work is the result of a collaboration among a natural gas producer, an EPC (Engineering, Procurement, and Construction) company, a simulation software company and a research laboratory with the aim of improving the knowledge of the solubility limits of some key impurities in LNG. In this perspective, neopentane has been selected as a potential solid former because of its high triple point temperature, 256.6 K. In addition, the only two articles in the literature reporting solubility data of neopentane in methane (the main natural gas component) are not in agreement each other. A wide experimental investigation of the liquid-vapor, solid-vapor, solid-liquid, and solid-liquid-vapor equilibria for the methane + neopentane system at low temperature has been carried out and presented in Campestrini et al. 2022. This work shows how the data produced by the research laboratory are made available to industries thanks to the implementation of dedicated models and algorithms in a process simulator. In particular, an accurate model, based on the Soave-Redlich-Kwong (SRK) cubic Equation of State (EoS), has been developed for the phase equilibria of the methane + neopentane system including solid phases. In addition, a robust multi-phase flash algorithm has been developed for the solid-liquid(-liquid)-vapor equilibrium calculation. Rigorous thermodynamic phase stability analysis is used to determine the correct number of phases that will coexist at any given temperature and pressure. The new model and the phase equilibrium algorithm are integrated in the process simulator to improve the accuracy in the representation of the phase boundaries in natural gas and to allow an optimized design of the liquefaction units.