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Simulation of a compressible powder flow under oscillatory shear stress modeled as a non-linear fluid by using an explicit solution method

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Journal of engineering Science and Technology Review 2018年第4期11卷 84-90页

作者： Robledo, Mauricio E. Obregón, Luis G. Velázquez, Carlos Research Group on Process Simulation and Coal Transformation Chemical Engineering Program Universidad del Atlántico Carrera 30 Número 8- 49 Puerto Colombia - Atlántico081007 Colombia Research Group on Sustainable Chemical and Biochemical Processes Chemical Engineering Program Universidad del Atlántico Carrera 30 Número 8- 49 Puerto Colombia - Atlántico081007 Colombia Chemical Engineering Department University of Puerto Rico Mayagüez Campus PO Box 9000 Mayagüez00681 Puerto Rico

The purpose of this research is to develop the modeling and simulation of a frictional and compressible powder flow subjected to oscillatory shear stress in a device that consists of a rectangular shaped cavity with a free surface, two oscillatory moving walls, and three non-moving walls. The finite differences method under the explicit scheme is used to approximate the real solution to the resulting equations from the mathematical modeling of the studied system. The simulation results were compared qualitatively with experimental results, and the solution method was verified by comparing the simulation results of a viscous glycerin flow with the results of the software STAR-CCM+ under the same conditions of the powder flow. The results showed that the powder velocity profiles were coherent with the experimental results. Furthermore, the solution method was validated finding that the 83.5% of the compared data presented absolute errors less than 0.5 cm/s. The complete velocity profiles obtained from the simulation help to have a deep understanding of the granular material behavior subjected to oscillatory shear stress. © 2018 Eastern Macedonia and Thrace Institute of Technology.

关键词： Shear stress

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Redox activity and stability of NiO-based oxygen transfer materials for sorption enhanced chemical looping steam methane reforming 21

Redox activity and stability of NiO-based oxygen transfer ma...

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21st International Congress of chemical and process engineering, CHISA 2014 and 17th Conference on process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2014

作者： Silvester, L. Heracleous, E. Antzara, A. Lemonidou, A.A. Bukur, D.B. Texas A and M University at Qatar Chemical Engineering Program Education city Doha23874 Qatar Chemical Process and Energy Resources Institute CERTH Thessaloniki57001 Greece Aristotle University of Thessaloniki Chemical Engineering Department Thessaloniki54124 Greece

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High-pressure phase behavior of ternary systems containing ionic liquids + carbon dioxide + organometallic compounds

High-pressure phase behavior of ternary systems containing i...

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2011 AIChE Annual Meeting, 11AIChE

作者： Peters, C.J. Kazemi, S. Kroon, M.C. Delft University of Technology Faculty of Mechanical Maritime and Materials Engineering Department of Process and Energy Netherlands Eindhoven University of Technology Department of Chemical Engineering and Chemistry Separation Technology Group Netherlands Petroleum Institute Chemical Engineering Program Abu Dhabi United Arab Emirates

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Effects of expansion foam on controlling LNG vaporization rate

Effects of expansion foam on controlling LNG vaporization ra...

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Fuels and Petrochemicals Division 2014 - Core programming Area at the 2014 AIChE Spring Meeting and 10th Global Congress on process Safety

作者： Zhang, Bin Liu, Yi Olewski, Tomasz Vechot, Luc Mannan, M. Sam Artie McFerrin Department of Chemical Engineering Mary Kay O'Connor Process Safety Center Texas A and M University College StationTX77843-3122 United States Chemical Engineering Program Texas A and M University at Qatar Doha Qatar

ISBN: (纸本)9781634390736

With increasing consumption of natural gas, the safety of liquefied natural gas (LNG) utilization has become a challenge that requires comprehensive studies on risk assessment in the LNG facilities with mitigation measures. The rapid vaporization after an LNG spill generates a vapor cloud, which is flammable at a concentration between roughly 5-15%v/v in the air. The LNG vapor is heavier than air and may migrate at the ground level over a long distance in a downwind direction, which increases the possibility of ignition resulting in fires. High expansion foam has been proved to be effective for mitigating vapor hazard and suppressing a pool fire. With respect to vapor hazard mitigation, high expansion foam may reduce the vaporization rate and increase vapor buoyancy. These effects have not been fully analyzed yet. In this work, a small-scale field experiment was performed to study the effect of high expansion foam on the vaporization rate of liquid nitrogen, used as a safe analog of LNG. It has been found that a foam blanket reduces convective and radiative heat flux to the pool. At the same time, the water drainage from collapsing foam adds additional heat to the pool;however, this was found to be small and negligible with the long lasting pools. Copyright © (2014) by AIChE All rights reserved.

关键词： Heat flux

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Assessment of hydrogen sulfide dispersion from dumpsite using AERMOD modeling system

Assessment of hydrogen sulfide dispersion from dumpsite usin...

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5th KKU International engineering Conference 2014, KKU-IENC 2014

作者： Kanabkaew, Thongchai Rakmak, Nirattisai Choosaeng, Sukonta Environmental Science Program Walailak University Nakhon Si Thammarat Thailand Geohazard Research Unit Walailak University Nakhon Si Thammarat Thailand Chemical and Process Engineering Program Walailak University Nakhon Si Thammarat Thailand

ISBN: (纸本)9783038350903

Hydrogen sulfide (H2S) isclassified as toxic gases that are commonly known to be generated from an anaerobic process, volcanic explosion and petroleum related processes. Low concentration of H2S causes irritation on human eyes and respiratory system as well as nuisance problem due to its rotten-egg smell. Insanitary dumpsite of municipal wastes containing high organic fraction could be a source of H2S emission, which affects the quality of life of nearby communities. This study assessed the H2S dispersion from dumpsite in Nakhon Si Thammarat using the source dispersion model, AERMOD. Emission rate of H2S generated at dumpsite was estimated using emission factor of 1.76 mg.m-2.d-1 taken from AP-42 (USEPA.). For meteorological data, hourly average data in 2012 were collected from three meteorological stations which were Nakhon Si Thammarat, Surat Thani and Trang Provinces. Meteorological data were primarily utilized from Nakhon Si Thammarat. Only missing values were filled by the data from Surat Thani and Trang, respectively. Results revealed that maximum concentrations of H2S in 2012 were 0.595, 0.066 and 0.058 ppb, respectively for 1 hour average (1st highest), 24 hour average (1st highest) and annual average over the study area of 10 km × 10 km surrounding the source. Maximum concentration of H2S emitted from dumpsite was mainly confined within 1.5 km surrounding the sources, particularly to the east and northeast area. The simulated concentrations of H2S did not exceed the suggested standard values;however, the 1st highest hourly average concentration was reached the odor threshold (0.5 ppb). To clarify the simulated H2S concentrations, further works should be included the field sampling of H2S at dumpsite to obtain the actual emission rate. Meteorological data in several years should be also used to provide the concrete pattern of H2S dispersion. © (2014) Trans Tech Publications, Switzerland.

关键词： Hydrogen sulfide

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Product distribution and reaction pathways during Fischer-Tropsch synthesis on an iron catalyst

Product distribution and reaction pathways during Fischer-Tr...

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27th Annual International Pittsburgh Coal Conference 2010, PCC 2010

作者： Bukur, Dragomir B. Nowicki, Lech Chemical Engineering Program Texas A and M University at Qatar P.O. Box 23874 Doha Qatar Department of Chemical Engineering Texas A and M University College Station TX 77843 United States Faculty of Process and Environmental Engineering Technical University of Lodz 90-924 Lodz Poland

ISBN: (纸本)9781617823213

A precipitated iron Fischer-Tropsch (F-T) catalyst was tested in a stirred tank slurry reactor under different process conditions. The extent of water-gas-shift (WGS) reaction increased with increase in conversion of the limiting reactant, indicating that the WGS is a consecutive reaction with respect to water formed in the F-T synthesis reaction. The experimental results indicate that 1-olefins participate in secondary reactions (e.g. 1-olefin hydrogenation, isomerization and readsorption). Secondary hydrogenation and isomerization of 1-olefins increased with increase in partial pressure of hydrogen. Gas residence time had significant effect on selectivity of ethylene and other gaseous 1-olefins. Chain growth probability factor increased with increase in molecular weight.

关键词： Fischer-Tropsch synthesis

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Stabilization of reaction-convective systems using inventory control

Stabilization of reaction-convective systems using inventory...

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American Control Conference (ACC)

作者： M.G. Ruszkowski B.E. Ydstie Process Systems Engineering Program Department of chemical Engineering Carnegie Mellon University Pittsburgh USA

In this work, we develop an approach for the control of multi-phase and distributed chemical process systems by considering the physics of a process coupled with inventory control, passivity and thermodynamics. The incidence of these theories allows us to assess the stability of a general, distributed process system and stabilize the performance around given fixed reference points. The theory we develop is applied to a simulated model of an electro-chemical process making Silicon, a pre-cursor material for electronics and silicones. Open and closed loop simulations are prepared and discussed.

关键词： Inventory control Silicon Control systems Partial differential equations chemical processes Thermodynamics Stability Modeling Distributed parameter systems State-space methods

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Investigating CO_(2) electro-reduction mechanisms:DFT insight into earth-abundant Mn diimine catalysts for CO_(2) conversions over hydrogen evolution reaction,feasibility,and selectivity considerations

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Frontiers of chemical Science and engineering 2024年第12期18卷 117-129页

作者： Murugesan Panneerselvam Marcelo Albuquerque Iuri Soter Viana Segtovich Frederico W.Tavares Luciano T.Costa MolMod-CS-Institute of Chemistry Fluminense Federal UniversityValonginho CampusCentroNiteroi 24020-14Rio de JaneiroBrazil Chemical Engineering Program(PEQ/COPPE) Federal University of Rio de Janeiro(UFRJ)Moniz AragaoRio de Janeiro21941-594RJBrazil Institute of Physics Fluminense Federal UniversityPraia Vermelha CampusGragoataNiteroiRio de JaneiroBrazil Chemical and Biochemical Process Engineering School of ChemistryFederal University of Rio de JaneiroRio de Janeiro 21941Brazil

This study investigates the detailed mechanism of CO_(2) conversion to CO using the manganese(I) diimine electrocatalyst [Mn(pyrox)(CO)3Br], synthesized by Christoph Steinlechner and coworkers. Employing density functional theory calculations, we thoroughly explore the electrocatalytic pathway of CO_(2) reduction alongside the competing hydrogen evolution reaction. Our analysis reveals the significant role of diimine nitrogen coordination in enhancing the electron density of the Mn center, thereby favoring both CO_(2) reduction and hydrogen evolution reaction thermodynamically. Furthermore, we observe that triethanolamine (TEOA) stabilizes transition states, aiding in CO_(2) fixation and reduction. The critical steps influencing the reaction rate involve breaking the MnC(O)–OH bond during CO_(2) reduction and cleaving the MnH–H–TEOA bond in the hydrogen evolution reaction. We explain the preference for CO_(2) conversion to CO over H_(2) evolution due to the higher energy barrier in forming the Mn-H_(2) species during H_(2) production. Our findings suggest the potential for tuning the electron density of the Mn center to enhance reactivity and selectivity in CO_(2) reduction. Additionally, we analyze potential competing reactions, focusing on electrocatalytic processes for CO_(2) reduction and evaluating “protonation-first” and “reduction-first” pathways through density functional theory calculations of redox potentials and Gibbs free energies. This analysis indicates the predominance of the “reduction-first” pathway in CO production, especially under high applied potential conditions. Moreover, our research highlights the selectivity of [Mn(pyrox)(CO)3Br] toward CO production over HCOO– and H_(2) formation, proposing avenues for future research to expand upon these findings by using larger basis sets and exploring additional functionalized ligands.

关键词： manganese carbonyl complex CO_(2)reduction reaction hydrogen evolution reaction selectivity density functional theory studies

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Dynamics of a distillation column with distributed and conventional approach using multivariable control with adjustment based on multiple errors

Dynamics of a distillation column with distributed and conve...

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2011 International Conference on Communications, Computing and Control Applications, CCCA 2011

作者： Marangoni, Cintia Teleken, Joel G. Parisotto, Iaçanã G. B. Werle, Leandro O. Bolzan, Ariovaldo MacHado, Ricardo A. F. University of Joinville Region - Univille Process Engineering Master's Program Mail Box 246 Joinville-SC 89219-905 Brazil Federal University of Santa Catarina UFSC Chemical Engineering Department Florianpolis - SC 88010-970 Brazil

ISBN: (纸本)9781424497959

In this study, an application of a multivariable conventional control structure of the continuous tray distillation columns is compared to a new distributed proposal. This was done considering the process dynamics, more specifically the transition time when the process is disturbed. As the conventional approach, the top and bottom product temperatures of the distillation column were selected as controlled variables and the reflux ratio and reboiler heat supply as manipulated variables. These loops plus an intermediate temperature column stage controlled using the heat supply of one tray as the manipulated variable comprised the distributed control structure. The regulator problem was considered for the experimental control studies. Feed temperature was chosen as the load variable. It is important to notice that this study focuses on the response process and does not address the development or design of the control structure. The main aim is to compare the time response of the process when subject to an expected disturbance using two different approaches (conventional and distributed). Experiments were carried out with multivariable PI controllers and the multiple errors (desired controller variable and the corresponding measured output) of each controlled variable were used together to computed the control actions (interactions were considered). Better performance in relation to transition time was observed with the distributed approach, indicating that this is an interesting strategy which could be used to minimize the transients in a distillation column. © 2011 IEEE.

关键词： Dynamics

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Clay, Phosphate Adsorption, Dispersion, and Rheology

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Water, Air, & Soil Pollution: Focus 2009年第5期9卷 403-407页

作者： Teo, J. Liew, W. K. Leong, Y. K. Chemical and Process Engineering Program School of Mechanical Engineering The University of Western Australia Crawley Australia School of Engineering James Cook University Townsville Australia

Soluble phosphate is a common ingredient of fertilizer used in agriculture production all over the world. This chemical mixed with soil is transported into the water and marine environment via rainfall causing a range of environmental problems such as toxic algae bloom. Kaolin clay is a common material found in soil and is used as a model system to understand the effects of phosphate adsorption on the flocculation/dispersion of the clay slurries. In the topics, torrential downpours are common. The large water flow will easily disperse the unflocculated or weakly flocculated sediments over a wide area including river and marine environments. Phosphate adsorption was found to weaken the interparticle forces between clay platelets in the slurries. At high enough concentration, it will completely deflocculate the clay slurries, i.e. the net interparticle force is repulsive. A deflocculated slurry is characterised by a low viscosity and no yield stress. As a result, it is much easier to disperse this slurry over a wide area possible even in a small downpour. This study will present the flow and yield stress behaviour of kaolin clay slurries under the influence of adsorbed phosphate.

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