Solid-fluid phase behavior in binary mixtures: A new classification focused on paraffin systems

QUINZIO, MARTINA JULIETA; TASSIN, NATALIA GISELLE; PORRAS GIRALDO, ANDRÉS FELIPE; RODRIGUEZ REARTES, SABRINA BELÉN; MARCELO SANTIAGO ZABALOY; CISMONDI, MARTÍN

Campinas

Conferencia; XII Iberoamerican Conference on Phase Equilibria and Fluid Properties for Process Design (Equifase 2022) / X Congresso Brasileiro de Termodinâmica Aplicada (CBTermo, 2022); 2022

UNICAMP

The high-pressure solid-fluid phase behavior of mixtures is important in a variety of real situations of industrial interest, including paraffin precipitation from hydrocarbon reservoir fluids, supercritical extraction or precipitation processes, and cryogenic processes among others. In the case of binary mixtures, such behaviors can give place to different topologies in terms of critical lines, three-phase lines, critical end points and quadruple points. The classification proposed by Yamamoto in 1989 for those topologies is probably the best known and most used one, besides being more complete than others when considering experimentally observed behaviors. Nevertheless, a number of publications and in particular two recent PhD theses developed in our groups, found different types of new topologies which deviate from the types considered in Yamamoto’s classification. These two theses employed different modelling approaches, differing essentially in considering the solid phase made of the heavy compound in pure state (N.G. Tassin, UNC 2020, IPQA, Córdoba) or made of a solid solution (A.F. Porras Giraldo, UNS 2021, PLAPIQUI, Bahía Blanca). The different deviations from the types in Yamamoto’s classification are compiled and analyzed in this work.Moreover, a new classification is proposed for asymmetric binary systems. Being motivated by the study of paraffin precipitation from reservoir fluids, this new classification limits the scope of Yamamoto’s classification by leaving out of consideration what happens in the lower temperature range up to the triple point of the light component while, on the other hand, it incorporates some possible behavior variations in the temperature range of more practical interest. The new classification is shown to cover all possible phase behavior evolutions in the binary series of methane or ethane or propane with a higher n-alkane, considering both, what is known so far in terms of experimental data, and some features predicted with different modelling approaches, which have not been confirmed yet at the experimental level.