A consistent Thermodynamic Model for Solid Liquid Equilibrium (SLE) and Vapor Liquid Equilibrium (VLE) in Aqueous Amine Solutions

AbstractTwo thermodynamic models (NRTL/UNIQUAC) were tested to model the SLE and VLE of the aqueous piperazine system. The reported 6 species in solid and liquid phases were represented successfully together with the estimated standard enthalpies and Gibbs energy of formation. The earlier reported experimental data for different SLE and VLE were found to be very useful for this work. The models consistently represent the experimental data. However, efforts are still needed to improve the model and a direct measurement of the solution heat capacity will reduce the number of fitted parameters

The Impact of Design Correlations on Rate-based Modeling of a Large Scale CO2 Capture with MEA

AbstractHydrodynamics and mass transfer correlations for the design of structured packed columns have been studied in order to compare the effect of different design correlations on the rate-based modeling of a large scale CO2 capture process with a chemical solvent. The commonly used correlations like the Bravo et al.,[1] and Billet and Schultes [2] were applied in this study for the prediction of mass transfer in an absorber column. Two cases are considered: absorption of CO2 from a gas-fired power plant (430 MWe) and absorption of CO2 from a coal-fired power plant (800 MWe). In this work a scale-up analysis with respect to the effect of correlations used on the performance of the system for CO2 capture with MEA was done within the Aspen RateSep simulator. The study showed that there is significant uncertainty associated with applying the proposed correlations for large scale packed columns for capturing CO2 from gas-fired and coal-fired power plants. The height of packed column varies in both gas-fired and coal-fired power plants with the selected correlations. It was found that there is more uncertainty in using the selected correlations for absorption of CO2 from gas fired power plant compared to a coal-fired power plant because of the lower CO2 concentration. The differences are caused by both the mass transfer and the effective interfacial area models

Prediction of N2O Solubility in Alkanolamine Solutions from the Excess Volume Property

AbstractThe CO2 solubility is very important property when establishing thermodynamic models for the VLE. In order to obtain the CO2 solubility the normal procedure is to use the N2O analogy as the CO2 solubility cannot be directly measured. This calls for a rather extensive experimental program. In this work a simple and less laborious model was developed based on the excess molar volumes to estimate the excess Henry's constant. This method only requires density data and the N2O solubility into pure solvents (Water/Alkanolamine). The model works well to represent experimental data for different temperatures and concentrations

Study on carbamate stability in the Amp/CO2/H2O system from 13C-NMR spectroscopy

AbstractQualitative and quantitative 13C NMR studies were performed on 30 wt % aqueous solution of 2-amino-2-methyl-1-propanol (AMP) with different amount of CO2 at 25 °C. The results suggested that the main species in this system are: AMP/AMPH+, AMPCO2− and HCO3−/CO32−. The carbamate was observed at low loading and the carbamate stability constant was calculated based only on the experimental species concentration from NMR analysis. Based on the liquid phase speciation from NMR, the carbamate stability constant on mol fraction basis was found to be about 0.47 at 25 °C

Modelling of high pressure binary droplet collisions

AbstractDroplet collision efficiency is a rather uncharted area for real hydrocarbon systems under non-atmospheric conditions. It is also of great interest in many industrial applications. In this work binary head-on droplet collisions at high pressure have been simulated using the lattice Boltzmann method. A model that captures the physics of the coalescence process is used where no external criterion for coalescence is needed. The collision process is described in terms of hydrodynamic variables and through a quantitative study of energy loss. At high pressures, low inertia collisions are the most frequent. Distinguishing between bouncing and coalescence under these conditions is needed in order to provide closure conditions for macroscopic CFD models. A limit of Re<170ρlg is found to predict coalescence in all the cases simulated. In addition this paper explains the stochastic behaviour of low inertia coalescence at high pressure. This has major implications both when building macroscopic models for predicting industrial process efficiencies and in the optimization of equipment internals working with droplets at high pressure as is the case for combustion chambers and gas–liquid separators

Viscoelastic model for particle fragmentation in olefin polymerization

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