A single-step protocol for closing experimental atom balances

Molar balances are considered to be closed if they are within 95-105%. It was shown in the companion paper "https://doi.org/10.1016/j.cej.2018.12.113; Chem. Eng. J., 361, 805-811 (2019)" that even this condition can give rise to pronounced deviations in conversion or selectivity data (Heynderickx, 2019). This manuscript offers a very simple a posteriori calculation procedure to address these deviations via simple linear algebra. The specific details of this procedure, called 'CLOBAL', after 'closing the balances', are shared (1) by showing the mathematics behind-the-scene and (2) by showing the specific programming code with an itemized guideline through the code. Key benefits of proposed procedure CLOBAL script are: Physical quantities such as molar flow rates, concentrations or absolute number of moles are updated via a one-step linear procedure to close the corresponding atom balances; The presented CLOBAL procedure, is executed in Excel (R), which is accessible and practical for every user - no need for special license and the code is provided; and Parameter estimation, using treated data, results in smaller confidence intervals and lower residual sum of squares (RSSQ). (C) 2020 The Author(s). Published by Elsevier B.V

Activity coefficients for liquid organic reactions : towards a better understanding of true kinetics with the synthesis of jasmin aldehyde as showcase

The aldol condensation of benzaldehyde and heptanal is taken as an example of reversible liquid phase organic reactions to show that inclusion of activity coefficients reveal distinct differences in conversion and product distribution when different solvents methanol, ethanol, n-propanol, or n-butanol are used. The purpose of this work is to show a pronounced solvent effect for a given set of identical kinetic parameters, i.e., the same liquid phase kinetics can result in different conversion and yield values, depending on the choice of solvent. It was shown that subsequent parameter estimation without inclusion of the activity coefficients resulted in a pronounced deviation from the true' kinetics, up to a factor of 30. It is proposed that the usage of average activity coefficients gives already a significant improvement, resulting in acceptable parameter estimates

CFD modeling of all gas-liquid and vapor-liquid flow regimes predicted by the Baker chart

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Assessment of a gas-solid vortex reactor for SO2/NOx adsorption from flue gas

The feasibility of performing the SO2/NOx adsorption process in a gas-solid vortex reactor (GSVR) is examined and compared with the more traditional riser technology. The multiphase reacting flow is modeled using the Eulerian-Eulerian two-fluid model. Models of nonreacting flows were validated using data from a bench-scale experimental setup. The GSVR has the potential to significantly improved heat/mass transfer between phases, as compared to more conventional fluidization technologies. Process intensification opportunities are investigated. The model predicts continuous removal efficiencies greater than 99% for SO2 and approximately 80% for NOx. The gas-solid slip velocity and convective mass transfer coefficient for the riser were 0.2-0.5 and 0.06-0.12 m/s, respectively, whereas the values for the GSVR were 6-7 and 1.0-1.1 m/s, respectively. This order of magnitude increase in the external mass transfer coefficient highlights the potential intensification opportunities provided by the GSVR

Removal of dimethylsulfide, n-hexane and toluene from waste air in a flat membrane bioreactor under continuous conditions

Dimethylsulfide (DMS), n-hexane and toluene removal from a waste air was carried out by using a flat composite membrane bioreactor under continuous feeding conditions. The composite membrane consisted of a dense polydimethylsiloxane top layer with an average thickness of 1.5 μm supported with a porous polyacrylonitrile layer of 50 μm. The membrane bioreactor (MBR) was operated during 9 months in which several operational conditions were applied. The inlet load of each compound ranged from 0 to 350 g m-3 h-1 and removal efficiencies of 80, 70 and 0 to 30 % were reached for DMS, toluene and hexane respectively. Two different empty bed residence time (EBRT) were applied on the MBR in order to check the influence of the residence time on the reactor performance. In this case, DMS and toluene removal increased with an increasing EBRT, while the removal of hexane remained constant. By increasing the flow rate of the recirculated liquid from 22 l min-1 to 45 l min-1, the total performance of the biofilter decreased. To increase the mass transfer of hexane in order to get a higher removal, an emulsion of water/silicone oil 80/20 V% was used as recirculated medium at the liquid side of the reactor. This caused a decrease in DMS removal while the removal of toluene remained constant. The variation on the hexane removal decreased significantly, so the reactor became more reliable for degrading hexane