Equilibrio Liquido Vapor

Abstract
We have performed molecular dynamics simulations at constant temperature and pressure to calculate the solubility of carbon dioxide (CO2) and hydrogen sulfide (H2S) in water. The solubility of gases in water is important in several technological problems, in particular in the petroleum industry. The calculated liquid densities as function of temperature are in good agreement withexperimental data. The results at the liquid–vapor equilibrium show that at low temperatures there is an important amount of gases at the interface. The adsorption of gases in the liquid phase decreases as temperatures increases.
Key words: Molecular dynamics simulations, acid gases, solubility.
 
Resumen
Se desarrollaron simulaciones de dinámica molecular a temperatura y presión constante paraobtener la solubilidad del dióxido de carbono (CO2) y del ácido sulfhídrico (H2S) en agua. La solubilidad de los gases en agua es importante en varios problemas tecnológicos, en particular en la industria del petróleo. Las densidades obtenidas en fase líquida a distintas temperaturas reproducen muy bien los datos experimentales. Los resultados en el equilibrio líquido–vapor muestran que hay una fuerteadsorción de gases en la interfase. La adsorción en la fase líquida disminuye con el aumento de la temperatura.
Palabras clave: Simulaciones de dinámica molecular, gases ácidos, solubilidad.
1 Introduction
The solubility of gases in mixed solvents is an important factor
for the design, development and optimization of various industrial processes. Gas solubility data are also useful inproviding
essential information about thermodynamic and structural
properties of solutions. The experimental determination of
the solubility of gases in liquids for industrial systems is well
known [1, 2]. These measurements are expensive because the
conditions of pressure and temperature they are carried out.
Nevertheless, it is necessary to understand the available experimental data andorganize them over a wide range of temperatures and pressures to be used in the modeling of vapor-liquid
equilibrium.
The two main reasons to investigate the thermodynamic
properties of carbon dioxide water are the application to the oil
and gas industry and CO2
sequestration. Carbon dioxide and
water are often found together in natural gas streams and also
in oil reservoirs as part ofenhanced oil recovery. The presence of carbon dioxide and water in these environments may
cause complications such as corrosion and hydrate formation.
On the other hand, various CO2
sequestration schemes have
generated significant interest in the thermodynamic properties
of carbon dioxide-water systems. Besides, the issue of global
climate change due to emissions of so-calledgreenhouse gases
including carbon dioxide is of great importance to the future
development of energy and power technology. It is for that
reason that studies have been performed to remove carbon
dioxide from natural or refinery gases. The CO2
adsorption
into a liquid agent is the most commonly used process for the
bulk removal of CO2
. Accurate knowledge of the behavior of
these systemsover a wide range of pressures and temperatures
is essential for industrial applications. In particular, reliable
solubility data of carbon dioxide in water over a wide range
of temperatures and pressures are necessary to develop and to
validate especially adapted thermodynamic models.
Accurate knowledge of phase behavior in water-H2
S systems is crucial for designing and operation ofpipelines and
production/processing facilities as many sour reservoir fluids
containing hydrogen sulfide and water. In general, it is desirable to avoid the formation of condensed water to reduce the
risk of gas hydrate formation, ice formation, corrosion, and
two-phase flow problems. On the other hand, oil and gas producers have been faced with a growing challenge to reduce
atmospheric...