Wilson Grava

Linear Driving Force Model in Carbon Dioxide Capture by Adsorption

In this work, experimental data of CO2 capture by adsorption was determined gravimetrically, at 30 °C and pressures up to 40 bar, and in a fixed bed unit at 20 bar, using NaY as adsorbent. Langmuir, Sips and Tóth isotherm models were used to correlate the equilibrium data. Sips and Tóth models were best fitted allowing estimate the maximum CO2 adsorbed amount. The breakthrough curve was modeled using Linear Driving Force (LDF) and Thomas models. The LDF model represented better the CO2 breakthrough curve than Thomas model. The mass transfer resistance in NaY micropores can be assumed as the limiting step for CO2 adsorption in fixed bed, since the intraparticle mass transfer coefficient of LDF model was smaller than the experimental overall volumetric mass transfer coefficient, although external film resistance is not negligible.

Simulation of an Off-shore Natural Gas Purification Process for CO2 Removal with Gas-Liquid Contactors Employing Aqueous Solutions of Ethanolamines

1.Abstract Brazilian Pre-Salt oil reserves present associated natural gas (NG) exhibiting high concentrations of CO 2 which requires gas purification processes for compliance with specifications imposed by the local Regulatory Agency. Due to its recognized small footprint as compared to amine based absorption route, membrane equipment show considerable potential for offshore applications. Of particular interest is the use of contactors, which combines membrane permeation with facilitated transport via liquid absorption. Process design and optimization of such innovative alternative demand flexible models to predict equipment performance at a variety of process conditions. This work presents a mathematical tool for analyzing CO2 separation with hollow-fiber membrane contactors, using aqueous solutions of ethanolamines. The model is applied to assess the technical feasibility of offshore CO 2 separation with membrane contactors. The developed simulator is based on rigorous principles of thermodynamics, fluid mechanics, heat transfer and mass transport. Chemical absorption modeling is approached as a typical application of the well known Chemical Theory, which aims to model chemically and/or physically complex equilibrium systems via a set of chemical equilibrium processes involving real and fictitious species. Vapor–liquid Equilibria of real species are superimposed on the multi-reaction chemical equilibria for formation of fictitious species - non-ionic and non-volatile complexes. A process flowsheet is simulated to assert technical feasibility of this technology to offshore installations.