CFD Study of Particle Flow Patterns in a Rotating Cylinder Applying OpenFOAM and Fluent

A rotating cylinder (RC) is a common type of reactor used in the industry, the most typical example being a cement kiln. The particle flow pattern inside such a unit is necessary for the mass and energy transfer, and this flow pattern depends on the operational Froude number and the degree of filling. The main aim of this study is to compare the simulation results from OpenFOAM and Fluent applying a Eulerian multiphase flow modeling concept to study the behavior of dense particle gas mixtures under different operational conditions. Six different flow patterns are simulated, varying the degree of filling from 10 to 45 % and the Froude number from 0.0001 to 5. OpenFOAM is capable of producing results very close to those generated with Fluent, and both software appears to be suitable for simulating the RC dense particle flow using the Eulerian approach

Physicochemical data for amine based CO2 capture process

Amine based post-combustion carbon capture is a highly discussed CO2 removal method from flue gas. Large-scale CO2 capture facilities with effective solvents are required to make a significant impact on reducing CO2 emissions from power plants and existing facilities. Physical properties of solvents play a major role in designing process equipment. Measured properties like density, viscosity and surface tension are used in mathematical models developed for mass transfer and interfacial area that are used in designing absorption columns. Further, developed correlations to represent measured physical properties are useful in process simulations. This work presents measured density and viscosity data of both CO2 loaded and non-loaded aqueous amine mixtures at different amine concentrations, temperatures and CO2 loadings. Density and viscosity increase with the increase of CO2 loading and decrease with the increase of temperature. The excess volume of binary and ternary aqueous amine mixtures was calculated from measured density data and correlated using a Redlich-Kister type polynomial. A density correlation proposed by Aronu was adopted to correlate densities of MEA + H2O mixtures. A correlations based on density deviation were proposed for MDEA + H2O, DMEA + H2O and DEEA + H2O mixtures. Aronu’s density correlation was modified to fit densities of MEA + H2O + CO2 mixtures. For AMP + MEA + H2O + CO2 mixtures, density was correlated using a modified Weiland’s correlation and a Setschenow type correlation. The accuracies of density data fits were satisfactory as the average absolute relative deviation (AARD) was typically less than 1% and correlations are suitable to perform engineering calculations. Eyring’s viscosity model based on Eyring’s absolute rate theory was adopted to calculate the free energy of activation for viscous flow ∆0+ of CO2 loaded and non-loaded aqueous amine mixtures. Further, the excess free energy of activation for viscous flow ∆0+ was calculated and a Redlich-Kister type polynomial was proposed to fit the measured viscosities of aqueous amine mixtures. For the mixtures of MEA + H2O + CO2 and AMP + MEA + H2O + CO2, empirical correlations were proposed to fit calculated ∆0+ from Eyring’s viscosity model and then the correlation was used to represent the measured viscosities. The viscosity deviation was determined for aqueous amine mixtures to investigate types of intermolecular interactions in the mixtures. Further, a modified Weiland’s correlation and a Setschenow type correlation were proposed to correlate viscosities of AMP + MEA + H2O + CO2 mixtures. The accuracies of the viscosity data fits were typically less than 2% AARD and the proposed correlations can be recommended to use in engineering calculations. The approach of using feedforward backpropagation artificial neural networks (ANNs) to represent densities and viscosities of CO2 loaded and non-loaded aqueous amine solutions gained high accuracies in data fit compared to the conventional empirical correlations. The ANNs are with multiple inputs of mole fractions of amines, CO2 and temperature of the mixtures, one hidden layer and one output that is either density or viscosity of the mixtures. The optimum number of neurons in the hidden layer was found by calculating Mean Squared Error (MSE) over thirty neurons. The experiments performed in a CO2-rig located at USN Porsgrunn illustrates the variations of density and viscosity at the top and the bottom of the absorber column at different liquid flow rates. The density of the solvent increased although the temperature increased due to the exothermal reaction between CO2 and MEA. The influence of temperature increase caused to decrease the viscosity at the bottom of the column even the CO2 loading is higher than at the top of the column. Process simulations were performed to predict the variations of density and viscosity of the column

Aspen Hysys and Aspen Plus Simulations for Amine Based Absorption Process Compared to Results from Experiments in CO2-RIG

In this study, equilibrium-based and rate-based simulations in Aspen HYSYS and Aspen Plus were performed to compare the removal efficiency and physical properties of density and viscosity in a CO2 absorption column. The experimental results from our previous study were used for comparison. In the equilibrium-based simulations, removal efficiency at 40 kg/hr of solvent flow rate was fitted with simulation by adjusting the Murphree efficiency of 12% in all stages. Accordingly, the equilibrium-based performed for other considered flow rates by keeping adjusted constant Murphree efficiency for all the stages in the absorber column. The variations of physical properties like density and viscosity were simulated and compared with measured properties under three different liquid to gas (L/G) ratios. Performed rate-based simulations with default molar volume/density and viscosity models of Clarke model and Jones-Dole model respectively were able to predict the properties with acceptable accuracy, but a deviation of 25% between measured and simulated viscosities for the lean MEA mixture was observed

Aspen Hysys and Aspen Plus Simulations for Amine Based Absorption Process Compared to Results from Experiments in CO2-RIG

In this study, equilibrium-based and rate-based simulations in Aspen HYSYS and Aspen Plus were performed to compare the removal efficiency and physical properties of density and viscosity in a CO2 absorption column. The experimental results from our previous study were used for comparison. In the equilibrium-based simulations, removal efficiency at 40 kg/hr of solvent flow rate was fitted with simulation by adjusting the Murphree efficiency of 12% in all stages. Accordingly, the equilibrium-based performed for other considered flow rates by keeping adjusted constant Murphree efficiency for all the stages in the absorber column. The variations of physical properties like density and viscosity were simulated and compared with measured properties under three different liquid to gas (L/G) ratios. Performed rate-based simulations with default molar volume/density and viscosity models of Clarke model and Jones-Dole model respectively were able to predict the properties with acceptable accuracy, but a deviation of 25% between measured and simulated viscosities for the lean MEA mixture was observed.publishedVersio

Comparison of the influence of drag models in CFD simulation of particle mixing and segregation in a rotating cylinder

CFD modelling was used to simulate particle segregation in a transverse plane of a rotating cylinder under different particle-particle drag models. The Eulerian method was used to model the dense particulate phases in the system. Two types of particles, with different density and size, were used in the study. The simulations were performed under the rolling mode since this mode is believed to give good particle-particle mixing. The drag models of Schiller-Naumann, Morsi- Alexander and Syamlal-O’Brien Symmetric were applied in the modelling of particle-particle drag and results were compared with experiments. All the drag models were able to model the particle segregation. The Schiller-Naumann model and the Morsi-Alexander model showed good agreement with the experimental results while the Syamlal-O’Brien-Symmetric model had some deviations

Physical Properties of MEA + Water + CO2 Mixtures in Postcombustion CO2 Capture: A Review of Correlations and Experimental Studies

The knowledge of physicochemical properties of a mixture of amine, water, and CO2 is beneficial in evaluating the postcombustion CO2 capture process and process equipment design. This study reviews the literature of density, viscosity, and surface tension measurements with the evaluated measurement uncertainties and proposed correlations for monoethanol amine (MEA), water, and CO2 mixtures. Adequate research has been performed to measure and develop correlations for pure MEA and aqueous MEA mixtures, but further studies are required for CO2-loaded aqueous MEA mixtures. The correlations fit measured properties with an acceptable accuracy, and they are recommended to use in process equipment design, mathematical modelling, and simulations of absorption and desorption

Density, viscosity and free energy of activation for viscous flow of monoethanol amine (1) + H2O (2) + CO2 (3) mixtures.

Densities and viscosities of aqueous monoethanol amine (MEA) and CO2-loaded aqueous MEA are highly relevant in engineering calculations to perform process design and simulations. Density and viscosity of the aqueous MEA were measured in the temperature range of 293.15 K to 363.15 K with MEA mass fractions ranging from 0.3 to 1.0. Densities of the aqueous MEA were fitted for a density correlation. Eyring’s viscosity model based on absolute rate theory was adopted to determine the excess free energy of activation for viscous flow of aqueous MEA mixtures and was correlated by a Redlich–Kister polynomial. Densities and viscosities of CO2-loaded MEA solutions were measured in the temperature range of 293.15 K to 353.15 K with MEA mass fractions of 0.3, 0.4 and 0.5. The density correlation used to correlate aqueous MEA was modified to fit CO2-loaded density data. The free energy of activation for viscous flow for CO2-loaded aqueous MEA solutions was determined by Eyring’s viscosity model and a correlation was proposed to represent free energy of activation for viscous flow and viscosity. This can be used to evaluate quantitative and qualitative properties in the MEA + H2O + CO2 mixture

Density, Viscosity, and Excess Properties of MDEA + H2O, DMEA + H2O, and DEEA + H2O Mixtures

This study presents measured density and viscosity of N-methyldiethanolamine (MDEA) + H2O, Dimethylethanolamine (DMEA) + H2O, and Diethylethanolamine (DEEA) + H2O mixtures. The density was measured at amine mass fraction w1 from 0.3 to 1 for the temperature range 293.15–353.15 K. The excess molar volumes VE were determined from density data. Redlich–Kister type polynomials were proposed to fit VE and density deviation ln(ργ) to represent measured densities. The viscosity was measured at amine mass fraction w1 from 0.3 to 1 for the temperature range 293.15–363.15 K. The viscosity deviation ηE and excess free energy of activation for viscous flow ΔGE* were determined from measured viscosities and examined for intermolecular interactions among mixture molecules. Correlations were proposed to fit viscosity data with acceptable accuracies. The McAllister’s three-body model was adopted to fit kinematic viscosities determined from density and dynamic viscosity data. The results showed the importance of examining intermolecular interactions that are discussed in McAllister’s four-body model to improve the accuracies of data fits

Model uncertainty of interfacial area and mass transfer coefficients in absorption column packings

Uncertainty in model input parameters propagates through the model to make model output imprecision. Here, mathematical models used to calculate interfacial area and mass transfer coefficient for both random and structured packing in a packed bed absorption column was studied to investigate the propagation of model input parameters of viscosity, density and surface tension through the models. Monte Carlo simulation was used to examine the uncertainty propagation, and expectation E(Y) and standard deviation s for the model output values were determined. This study reveals ±5% model output uncertainty for mass transfer coefficient and ±3.7% uncertainty for interfacial area for the Onda, Bravo and Fair models used in random packings. Further, the analysis predicts ±1.3% of uncertainty for interfacial area and ±0.8% of uncertainty for mass transfer coefficient for the Rocha’s correlations used in structured packings

Free Energies of Activation for Viscous Flow of Different Amine Mixtures in Post Combustion CO2 Capture

The viscosity of ternary mixtures of N-methyldiethanol amine (MDEA) + monoethanol amine (MEA) + H2O, Nmethyldiethanol amine (MDEA) + diethanol amine (DEA) + H2O and 2-amino-2-methyl-1-propanol (AMP) + diethanol amine (DEA) + H2O were correlated using Eyring’s viscosity model based on absolute rate theory. The correlations were capable of representing viscosity data within AARD 1.9%, 1.4% and 2.1% for the mixtures MDEA + MEA + H2O, MDEA + DEA + H2O and AMP + DEA + H2O respectively. These accuracies are acceptable in engineering calculations. The excess properties of volume , viscosity and free energy of activation for viscous flow Δ∗ were studied to understand the intermolecular interactions in the mixtures. The study shows that all mixtures have a negative sign for , and a positive sign for Δ∗. This indicates weak intermolecular interactions in mixtures compared to the pure liquids and strong molecular attractions like H-bonds in the mixtures