Benedikt Weber , Maximilian von Campenhausen , Tim Maßmann, Andreas Bednarz, Andreas Jupke
{"title":"CFD based compartment-model for a multiphase loop-reactor","authors":"Benedikt Weber , Maximilian von Campenhausen , Tim Maßmann, Andreas Bednarz, Andreas Jupke","doi":"10.1016/j.cesx.2019.100010","DOIUrl":"10.1016/j.cesx.2019.100010","url":null,"abstract":"<div><p>In multiphase devices, fluid dynamics have a high impact on concentration profiles and mass transfer between the phases and therefore influence efficiency. Standard models often assume ideally mixed conditions or plug flow. The application of such models for multiphase devices with complex flow patterns causes inaccuracies, if the flow deviates from ideally mixed or plug flow conditions. Therefore, for a precise model based design and operation parameter determination of devices with complex flow patterns, the local fluid dynamics should be considered. CFD simulations for multiphase systems including mass transfer, population balance equations for coalescence and breakage as well as reactions are still time consuming. Thus, we developed a compartment-model based on prior calculated CFD flow-data. In the CFD simulations, the time consuming population balance equations for coalescence and breakage, mass transfer and reactions are neglected. These phenomena are considered in the compartment-model. Thereby we reduce the overall computing time.</p><p>This paper presents the CFD based compartment-model applied on a loop-reactor. First, a three-phase CFD model of the developed multiphase loop-reactor is introduced. Following, the paper presents the compartment-model and the application of a time-driven constant-number Monte-Carlo approach to solve population balances. Finally, the compartment-model is applied to the liquid-liquid extraction part of the loop-reactor calculating the drop size distribution and mass transfer based on previously calculated CFD data.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100010"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43645407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Design and optimization of Kemira-Leonard process for formic acid production","authors":"W.X. Chua, S. da Cunha, G.P. Rangaiah, K. Hidajat","doi":"10.1016/j.cesx.2019.100021","DOIUrl":"10.1016/j.cesx.2019.100021","url":null,"abstract":"<div><p>Formic acid (FA) is a chemical with numerous industrial applications. Available literature including patents on FA processes are limited and do not provide sufficient information for process simulation. In the present study, a conventional FA process, known as the Kemira-Leonard (KL) process, for producing 98 wt% FA is developed and simulated using Aspen Plus V9. Then, heat integration and optimization of the process for two objectives (namely, minimization of total capital cost and annual utility cost) are performed. Finally, further improvement of the optimized process via vapor recompression (VR) is investigated. Bi-objective optimization provides many Pareto-optimal solutions for selection. Total annual cost (TAC) of the chosen optimized KL process without VR is found to be $19,887,834 (=0.724 USD/kg of FA produced), with total capital cost of $18,476,733. Addition of VR brings savings of $1,560,427 in annual utility cost, with an additional investment of $2,517,191 for the compressor and new heat exchangers; overall, this leads to TAC reduction of $1,035,748 (by 5.2%). Unit TAC after VR addition is 0.686 $/kg of FA produced.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100021"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45542896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A.J. Buttress , G. Hargreaves , A. Ilchev , T. Monti , A. Sklavounou , J. Katrib , P. Martin-Tanchereau , M.G. Unthank , D.J. Irvine , C.D. Dodds
{"title":"Design and optimisation of a microwave reactor for kilo-scale polymer synthesis","authors":"A.J. Buttress , G. Hargreaves , A. Ilchev , T. Monti , A. Sklavounou , J. Katrib , P. Martin-Tanchereau , M.G. Unthank , D.J. Irvine , C.D. Dodds","doi":"10.1016/j.cesx.2019.100022","DOIUrl":"10.1016/j.cesx.2019.100022","url":null,"abstract":"<div><p>Current industrial production of polymer resins is generally undertaken in large multi-tonne stirred tank reactors. These are characterised by relatively slow heating and cooling cycles, resulting in long vessel cycle times and extended production campaigns. In this work we present a design for a hybrid microwave/oil jacket proof of concept system capable of producing up to 4.1 kg of polymer resin per batch. By exploiting rapid volumetric heating effects of microwave energy at 2.45 GHz, we have optimised the synthetic regime, such that a 3.7 kg batch of polyester resin pre-polymer can be made in only 8 h 20 min, with higher molecular weight (M<sub>n</sub> 2100) compared to the conventional process taking 22 h 15 min (M<sub>n</sub> 1200), yielding an increase in synthesis rate of at least 265%. The increase in polymer molecular weight also suggests a higher conversion was achieved over a shorter time scale.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100022"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46166324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alija Vila , Sathish K.P. Sanjeevi , Johan T. Padding , Stefan Pirker
{"title":"Gas flow through static particle arrangements with a channel: Resolved simulations and analytic considerations","authors":"Alija Vila , Sathish K.P. Sanjeevi , Johan T. Padding , Stefan Pirker","doi":"10.1016/j.cesx.2019.100015","DOIUrl":"10.1016/j.cesx.2019.100015","url":null,"abstract":"<div><p>Fractures of particle assemblies happen frequently in dense gas-solid systems leading to a notable heterogeneity in the particle configuration, especially in case of cohesive powders and non-spherical particle interlocking. In this work, we investigate the influence of such heterogeneities on the hydrodynamic drag by studying the idealized case of a random arrangement of spheres with a channel-like void region. More specifically, we introduce this heterogeneity to a homogeneous particle arrangement by shifting apart two bulk regions, such that a void channel divides particle bulk. Single-relaxation-time lattice Boltzmann simulations were performed to resolve fluid flow through such arrested particle configurations and calculate the corresponding gas-particle momentum exchange and pressure drop. The calculated drag forces acting on the solids for random sphere arrangement are in good agreement with previously reported results of Hill et al. (2001b), Tenneti et al. (2011), and Tang et al. (2015). However, the overall momentum exchange obtained for configurations containing a heterogeneity is significantly lower. Obviously, the channel allows for a by-passing of a considerable amount of the flow leading to a reduced overall pressure drop and thereby underestimating the minimum fluidization velocity in a fluidized bed. Based on these direct numerical simulations, we examine the overall pressure drop dependence on the characteristic length scale (i.e. width) of the channel-like heterogeneity <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span>, the superficial Reynolds number (30 <span><math><mrow><mo>⩽</mo></mrow></math></span> <em>Re</em> <span><math><mrow><mo>⩽</mo></mrow></math></span> 300), and the solid volume fraction in the dense (i.e. bulk) region (0.4 <span><math><mrow><mo>⩽</mo><msub><mrow><mi>ϕ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>⩽</mo></mrow></math></span> 0.55). The width of the channel is varied within the order of magnitude of particle diameter <span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>p</mi></mrow></msub></mrow></math></span> (1 <span><math><mrow><mo>⩽</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>/</mo><msub><mrow><mi>D</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>⩽</mo><mn>4.36</mn></mrow></math></span>), decreasing an overall solid volume fraction (0.25 <span><math><mrow><mo>⩽</mo><mi>ϕ</mi><mo>⩽</mo></mrow></math></span> 0.55). In addition to the numerical simulations, we derive (semi)-analytic correlations for the dense bulk region as well as for the channel. As the simulations range from laminar to transitional flow, providing a single pressure drop correlation is very challenging. Therefore, we estimate the channel pressure drop with the appropriate correlations selected according to calculated superficial Reynolds number. For laminar flow, we achieved a good agreement between a combined (i.e. bulk and channel) analytical predicti","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100015"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49029154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A quantitative and generalized assessment of bubble-induced turbulence models for gas-liquid systems","authors":"Ben Magolan, Nazar Lubchenko, Emilio Baglietto","doi":"10.1016/j.cesx.2019.100009","DOIUrl":"10.1016/j.cesx.2019.100009","url":null,"abstract":"<div><p>In gas-liquid systems, bubble motion and interaction with the surrounding liquid medium serves to dramatically modify the liquid turbulent kinetic energy profile. While several two-equation bubble-induced turbulence (BIT) models have been advanced to predict this phenomenon, the intrinsic non-linearities that accompany the solution of the governing equations, interfacial forces, and turbulence models complicate their assessment. This hinders understanding of model performance and obstructs necessary model improvements. Here, the mathematical formulation of existing BIT models is investigated, and selected models are quantitatively assessed through simulation of the entire Liu (1989) air/water pipe flow experimental database in OpenFOAM. Critical to this work is the approach adopted to decouple the connection between turbulence and momentum closures, which ensures physically consistent volume fraction profiles and enables fair comparison between models. The assessment reveals that existing closures struggle with reliably predicting the turbulent kinetic energy profile as well as routinely worsen mean flow predictions. These observations are used to propose a pathway for the assembly of new BIT model formulations.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100009"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48796211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Depth of penetration of bubbles entrained by an oscillated plunging water jet","authors":"Grégory Guyot , Alain Cartellier , Jean-Philippe Matas","doi":"10.1016/j.cesx.2019.100017","DOIUrl":"10.1016/j.cesx.2019.100017","url":null,"abstract":"<div><p>We present experimental measurements of the penetration depth of the bubble cloud generated by a plunging water jet, when this jet is oscillated parallel to the free surface. We demonstrate that when the Reynolds number is larger than <span><math><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> the penetration depth can be adequately described with the model introduced by Clanet and Lasheras (1997) for a non-oscillating jet tilted relative to the normal of the liquid surface, provided an effective inclination angle is introduced to account for the jet translation velocity. In the case of jets with a Reynolds number smaller than <span><math><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span>, we find that the penetration depth of the oscillated jet can be increased of up to 30% by moderate oscillation velocities. This increase of the penetration is due to the decrease of the mixing layer angle when the symmetry around the bubble cloud is broken by the oscillation. We finally discuss the shape of the overall region impacted by the oscillating bubble cloud. We show that there is a regime for which the penetration is maximum at the center of this region, and a regime for which the penetration is maximum at the periphery. We propose a cartography to predict when each regime is relevant.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100017"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41375047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Identification of flow regime in a bubble column reactor with a combination of optical probe data and machine learning technique","authors":"Onkar N. Manjrekar, Milorad P. Dudukovic","doi":"10.1016/j.cesx.2019.100023","DOIUrl":"10.1016/j.cesx.2019.100023","url":null,"abstract":"<div><p>In the present work, a data-driven model for identification of flow regime in a bubble column is developed by combining data from optical probe technique and machine learning. Optical probe data from previous work was combined with new data in the present work to expand the database for model development. A novel methodology for determination of two key parameters from the optical probe signal, bubble time and characteristic time of the signal, is presented. The significance of these two parameters is that they contain rich information on operating flow regime in the bubble column. A map of these two parameters for various operating conditions is created, showing points belonging to identical flow regime lie in a cluster. A machine learning methodology based on support vector analysis was developed to identify flow regime using map developed in this work. This approach was able to uniquely classify flow regimes for various experimental conditions on single map, which is the highlight of this work.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100023"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41643223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Production of high purity CO2 from air using solid amine sorbents","authors":"M.J. Bos, S. Pietersen, D.W.F. Brilman","doi":"10.1016/j.cesx.2019.100020","DOIUrl":"10.1016/j.cesx.2019.100020","url":null,"abstract":"<div><p>For CO<sub>2</sub> capture from air on a supported amine sorbent, the effects of water co-adsorption and steam purge on the CO<sub>2</sub> working capacity and energy requirement for CO<sub>2</sub> desorption are studied. Working capacities are studied by fixed bed operation for changing temperature, pressure and amount of steam purge. Results show that for pressure-temperature swing adsorption a temperature above 100 °C and a pressure below 200 mbar as desorption conditions are required to maximize CO<sub>2</sub> working capacity and reduce energy requirement for desorption. Co-adsorption of water reduces energy requirement due to an increased CO<sub>2</sub> working capacity. Application of a steam purge increases the CO<sub>2</sub> working capacity and hence reduces sorbent inventory required. However, the net energy requirement per kilogram CO<sub>2</sub> does not decrease due to the latent heat of water. Concluding, steam purge regeneration for air capture does not reduce opex but might reduce capex.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100020"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46501300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multiscale modeling of monolithic sponges as catalyst carrier for the methanation of carbon dioxide","authors":"Lars Kiewidt , Jorg Thöming","doi":"10.1016/j.cesx.2019.100016","DOIUrl":"10.1016/j.cesx.2019.100016","url":null,"abstract":"<div><p>Solid sponges provide large surface areas, low pressure drops, and excellent heat transport properties and are thus promising monolithic catalyst carriers. Their potential compared to randomly packed beds at industrial scales, however, is largely unknown. To facilitate scale-up and future simulation studies, we present a 2-d mulstiscale reactor model for catalytic sponges. Therefore, we couple a 2-d pseudo-homogeneous reactor model with a 1-d reaction–diffusion model to explicitly consider heat and mass transfer and diffusional limitations at the catalyst scale. A comparison of simulated temperature profiles with experimental ones during CO<sub>2</sub> methanation at the lab scale demonstrates the validity of the developed model. Further, the results show that it is necessary to include heat and mass transport at the catalyst scale to adequately simulate concentration and temperature distributions in solid sponges although the applied catalyst layers are typically thinner than 100 <span><math><mrow><mi>μ</mi></mrow></math></span>m. The presented model thus allows to obtain insights into the interplay between heat and mass transport at both, the reactor and the catalyst scale, and provides a solid foundation for scale-up and techno-economic studies to assess the performance of solid sponges as catalyst carrier at industrial scales.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100016"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41713349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Barry W. Fitzgerald, Ahad Zarghami, Vinay V. Mahajan, Sathish K.P. Sanjeevi, Ivan Mema, Vikrant Verma, Yousef M.F. El Hasadi, Johan T. Padding
{"title":"Multiscale simulation of elongated particles in fluidised beds","authors":"Barry W. Fitzgerald, Ahad Zarghami, Vinay V. Mahajan, Sathish K.P. Sanjeevi, Ivan Mema, Vikrant Verma, Yousef M.F. El Hasadi, Johan T. Padding","doi":"10.1016/j.cesx.2019.100019","DOIUrl":"10.1016/j.cesx.2019.100019","url":null,"abstract":"<div><p>In this paper, we present a number of key numerical methods that can be used to study elongated particles in fluid flows, with a specific emphasis on fluidised beds. Fluidised beds are frequently used for the production of biofuels, bioenergy, and other products from biomass particles, which often have an approximate elongated shape. This raises numerous issues in a numerical approach such as particle-particle contact detection and the accurate description of the various hydrodynamic forces, such as drag, lift, and torque, that elongated particles experience when moving in a fluid flow. The modelling is further complicated by a separation of length scales where industrial flow structures that can extend for many metres evolve subject to solid-solid and solid-fluid interactions at the millimetre scale. As a result, it is impossible to simulate both length scales using the same numerical approach, and a multiscale approach is necessary. First, we outline the direct numerical simulation (DNS) approach that may be employed to estimate hydrodynamic force closures for elongated particles in a fluid flow. We then describe the key aspects of a CFD-DEM approach, which can be used to simulate laboratory scale fluidisation processes, that must be addressed to study elongated particles. Finally, we briefly consider how current industrial-scale models, which concretely assume particle sphericity, could be adapted for the simulation of large collections of elongated particles subject to fluidisation.</p></div>","PeriodicalId":37148,"journal":{"name":"Chemical Engineering Science: X","volume":"2 ","pages":"Article 100019"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.cesx.2019.100019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44978006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}