Documents disponibles écrits par cet auteur

Compartment modeling and flow characterization in nonisothermal underground coal gasification cavities / Sateesh Daggupati in Industrial & engineering chemistry research, Vol. 51 N° 12 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4493–4508 Titre : Compartment modeling and flow characterization in nonisothermal underground coal gasification cavities Type de document : texte imprimé Auteurs : Sateesh Daggupati, Auteur ; Ramesh N. Mandapati, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2012 Article en page(s) : pp. 4493–4508 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas  flow  Cavities Résumé : Characterization of reactant gas flow patterns in the underground coal gasification (UCG) cavity is important, because the flow is highly nonideal and likely to influence the quality of the product gas. In our earlier work [Daggupati et al., Energy2010, 35, 2374–2386], we have demonstrated a computational fluid dynamics (CFD)-based modeling approach to analyze the flow patterns in the cavity. A compartment model (network of ideal reactors) for the UCG cavity was developed based on the CFD simulation results. These studies were performed assuming that the UCG cavity is isothermal. In reality, large temperature gradients may prevail under certain conditions and, in turn, may influence the flow patterns. In this work, we consider different possible nonisothermal scenarios in the UCG cavity and propose a simplified compartment modeling strategy to reduce the computational burden. We also examine the effect of various operating and design parameters such as coal spalling, feed flow rate, feed temperature, and orientation of the inlet nozzle. All these effects are quantified by determining the corresponding compartment model parameters. The sensitivity of the compartment model parameters, with respect to the changes in various conditions, is studied. Furthermore, we validate the compartment modeling approach by comparing predicted conversions for a water-gas shift reaction with that of reaction-enabled CFD simulations under nonisothermal conditions. The results presented here provide adequate insight into the UCG process and can be conveniently used in the development of a computationally inexpensive phenomenological process model for the complex UCG process. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200410u [article] Compartment modeling and flow characterization in nonisothermal underground coal gasification cavities [texte imprimé] / Sateesh Daggupati, Auteur ; Ramesh N. Mandapati, Auteur ; Sanjay M. Mahajani, Auteur . - 2012 . - pp. 4493–4508. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4493–4508 Mots-clés : Gas  flow  Cavities Résumé : Characterization of reactant gas flow patterns in the underground coal gasification (UCG) cavity is important, because the flow is highly nonideal and likely to influence the quality of the product gas. In our earlier work [Daggupati et al., Energy2010, 35, 2374–2386], we have demonstrated a computational fluid dynamics (CFD)-based modeling approach to analyze the flow patterns in the cavity. A compartment model (network of ideal reactors) for the UCG cavity was developed based on the CFD simulation results. These studies were performed assuming that the UCG cavity is isothermal. In reality, large temperature gradients may prevail under certain conditions and, in turn, may influence the flow patterns. In this work, we consider different possible nonisothermal scenarios in the UCG cavity and propose a simplified compartment modeling strategy to reduce the computational burden. We also examine the effect of various operating and design parameters such as coal spalling, feed flow rate, feed temperature, and orientation of the inlet nozzle. All these effects are quantified by determining the corresponding compartment model parameters. The sensitivity of the compartment model parameters, with respect to the changes in various conditions, is studied. Furthermore, we validate the compartment modeling approach by comparing predicted conversions for a water-gas shift reaction with that of reaction-enabled CFD simulations under nonisothermal conditions. The results presented here provide adequate insight into the UCG process and can be conveniently used in the development of a computationally inexpensive phenomenological process model for the complex UCG process. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200410u

Entrainer based reactive distillation for esterification of ethylene glycol with acetic acid / Suman Thotla in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9461–9470 Titre : Entrainer based reactive distillation for esterification of ethylene glycol with acetic acid Type de document : texte imprimé Auteurs : Suman Thotla, Auteur ; Seethamraju Srinivas, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2010 Article en page(s) : pp. 9461–9470 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Entrainer  Reactive  distillation  Acetic  acid Résumé : In this paper, we study the potential of entrainer in reactive distillation involving high boiling reactants to decrease the reactive stage temperature and for separation of one of the products to enhance the conversion. Esterification of ethylene glycol with acetic acid in the presence of Amberlyst 36 with 1,2-dichloro ethane (EDC), as an entrainer, is chosen as the model reaction. The effect of different parameters on selectivity of diacetate of ethylene glycol (DAEG) in entrainer based reactive distillation (EBRD) has been studied both through experiments and simulations. The results show that, by using entrainer, it is possible to obtain close to 100% selectivity toward diester even with a stoichiometric mole ratio, which is otherwise not possible in a conventional reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801886q [article] Entrainer based reactive distillation for esterification of ethylene glycol with acetic acid [texte imprimé] / Suman Thotla, Auteur ; Seethamraju Srinivas, Auteur ; Sanjay M. Mahajani, Auteur . - 2010 . - pp. 9461–9470. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9461–9470 Mots-clés : Entrainer  Reactive  distillation  Acetic  acid Résumé : In this paper, we study the potential of entrainer in reactive distillation involving high boiling reactants to decrease the reactive stage temperature and for separation of one of the products to enhance the conversion. Esterification of ethylene glycol with acetic acid in the presence of Amberlyst 36 with 1,2-dichloro ethane (EDC), as an entrainer, is chosen as the model reaction. The effect of different parameters on selectivity of diacetate of ethylene glycol (DAEG) in entrainer based reactive distillation (EBRD) has been studied both through experiments and simulations. The results show that, by using entrainer, it is possible to obtain close to 100% selectivity toward diester even with a stoichiometric mole ratio, which is otherwise not possible in a conventional reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801886q

Experiments and kinetic modeling for CO2 gasification of indian coal chars in the context of underground coal gasification / Ramesh Naidu Mandapati in Industrial & engineering chemistry research, Vol. 51 N° 46 (Novembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15041-15052 Titre : Experiments and kinetic modeling for CO2 gasification of indian coal chars in the context of underground coal gasification Type de document : texte imprimé Auteurs : Ramesh Naidu Mandapati, Auteur ; Sateesh Daggupati, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2013 Article en page(s) : pp. 15041-15052 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Modeling  Coal  Coal  gasification  Carbon  dioxide  Kinetic  model Résumé : Gasification of four Indian coals is carried out in a CO2 atmosphere, using a thermogravimetric analyzer (TGA) to determine the intrinsic kinetics over a temperature range of 800―1050 °C with different partial pressures of CO2. The applicability of three models, viz., the volumetric reaction model, the shrinking core model and the random pore model, is evaluated. Of these three models, the random pore model is found to be the most suitable for all the coals considered in the current study. The dependence of the reaction rate on the gas-phase partial pressures is explained by the Langmuir― Hinshelwood model, and the parameters for the inhibition due to CO and CO2 are determined by performing experiments at different partial pressures. In underground coal gasification, the reaction takes place on reasonably large sized coal particles, wherein diffusion effects are significant. A one-dimensional reaction diffusion model is therefore developed in order to determine the diffusional resistance in the coal particle, and values of diffusivity are estimated. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679623 [article] Experiments and kinetic modeling for CO2 gasification of indian coal chars in the context of underground coal gasification [texte imprimé] / Ramesh Naidu Mandapati, Auteur ; Sateesh Daggupati, Auteur ; Sanjay M. Mahajani, Auteur . - 2013 . - pp. 15041-15052. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15041-15052 Mots-clés : Modeling  Coal  Coal  gasification  Carbon  dioxide  Kinetic  model Résumé : Gasification of four Indian coals is carried out in a CO2 atmosphere, using a thermogravimetric analyzer (TGA) to determine the intrinsic kinetics over a temperature range of 800―1050 °C with different partial pressures of CO2. The applicability of three models, viz., the volumetric reaction model, the shrinking core model and the random pore model, is evaluated. Of these three models, the random pore model is found to be the most suitable for all the coals considered in the current study. The dependence of the reaction rate on the gas-phase partial pressures is explained by the Langmuir― Hinshelwood model, and the parameters for the inhibition due to CO and CO2 are determined by performing experiments at different partial pressures. In underground coal gasification, the reaction takes place on reasonably large sized coal particles, wherein diffusion effects are significant. A one-dimensional reaction diffusion model is therefore developed in order to determine the diffusional resistance in the coal particle, and values of diffusivity are estimated. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679623

Feasibility of reactive distillation for Fischer-Tropsch synthesis. 2 / Seethamraju Srinivas in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4710–4718 Titre : Feasibility of reactive distillation for Fischer-Tropsch synthesis. 2 Type de document : texte imprimé Auteurs : Seethamraju Srinivas, Auteur ; Ranjan K. Malik, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2009 Article en page(s) : pp. 4710–4718 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Transportation  fuels  Fischer-Tropsch  Synthesis  technology  Reactive  distillation Résumé : The search for alternative sources of transportation fuels and energy security have revived an interest in the Fischer−Tropsch Synthesis (FTS) technology. Over the years, the main driver in FT reactor development has moved from the exothermic heat removal to the product distribution and selectivity. Reactive distillation (RD), a proven reactive separation method that can enhance yields and improve product selectivity in multiple reactant/product systems, was shown to be feasible for FTS in our earlier paper using a simplified kinetics [Srinivas, et al. Feasibility of Reactive distillation for Fischer−Tropsch Synthesis. Ind. Eng. Chem. Res. 2008, 48, 889−899]. This paper looks at the feasibility using a detailed kinetics incorporating olefin readsorption. In-built thermodynamic procedures of Aspen Plus, along with a detailed kinetic model that predicts product distribution, were used in performing the simulations. Some insight is given on the thermodynamics and kinetics used in performing the simulations. Conversion, yield, olefin-to-paraffin ratio, and product distribution are the parameters used for comparison among the different reactor types. Simulation results of the conventional reactors are compared with RD and it is seen that the performance of RD is at par or better than the conventional reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801887m [article] Feasibility of reactive distillation for Fischer-Tropsch synthesis. 2 [texte imprimé] / Seethamraju Srinivas, Auteur ; Ranjan K. Malik, Auteur ; Sanjay M. Mahajani, Auteur . - 2009 . - pp. 4710–4718. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4710–4718 Mots-clés : Transportation  fuels  Fischer-Tropsch  Synthesis  technology  Reactive  distillation Résumé : The search for alternative sources of transportation fuels and energy security have revived an interest in the Fischer−Tropsch Synthesis (FTS) technology. Over the years, the main driver in FT reactor development has moved from the exothermic heat removal to the product distribution and selectivity. Reactive distillation (RD), a proven reactive separation method that can enhance yields and improve product selectivity in multiple reactant/product systems, was shown to be feasible for FTS in our earlier paper using a simplified kinetics [Srinivas, et al. Feasibility of Reactive distillation for Fischer−Tropsch Synthesis. Ind. Eng. Chem. Res. 2008, 48, 889−899]. This paper looks at the feasibility using a detailed kinetics incorporating olefin readsorption. In-built thermodynamic procedures of Aspen Plus, along with a detailed kinetic model that predicts product distribution, were used in performing the simulations. Some insight is given on the thermodynamics and kinetics used in performing the simulations. Conversion, yield, olefin-to-paraffin ratio, and product distribution are the parameters used for comparison among the different reactor types. Simulation results of the conventional reactors are compared with RD and it is seen that the performance of RD is at par or better than the conventional reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801887m

Feasibility of reactive distillation for Fischer-Tropsch synthesis. 3. / Seethamraju Srinivas in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4719–4730 Titre : Feasibility of reactive distillation for Fischer-Tropsch synthesis. 3. Type de document : texte imprimé Auteurs : Seethamraju Srinivas, Auteur ; Ranjan K. Malik, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2009 Article en page(s) : pp. 4719–4730 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reactive  distillation  Multiple  reactant/product  systems  Fischer−Tropsch  Synthesis Résumé : Reactive distillation (RD), a proven reactive separation method that can enhance yields and improve product selectivity in multiple reactant/product systems, was shown to be feasible for FTS in our earlier papers using a simplified kinetics [Srinivas et al. Feasibility of Reactive Distillation for Fischer−Tropsch Synthesis. Ind. Eng. Chem. Res. 2008, 48, 889−899; DOI 10.1021/ie071094p] as well as a detailed kinetics [Srinivas et al. Feasibility of Reactive Distillation for Fischer−Tropsch Synthesis. 2. Ind. Eng. Chem. Res. 2009; DOI 10.1021/ie801887m]. In-built thermodynamic procedures of Aspen Plus, along with a detailed kinetic model that predicts product distribution, were used in performing the simulations. In this paper, we present detailed parametric studies like effect of reflux ratio, H2/CO feed ratio, number of nonreactive stages, etc. Conversion, yield, olefin-to-paraffin ratio and product distribution are the parameters used for comparison among the different cases studied. Within RD mode for FTS, some of the alternate column configurations like those with a side-heat removal and a side-draw, a hybrid column with reactive and nonreactive stages, are also explored and investigated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801888v [article] Feasibility of reactive distillation for Fischer-Tropsch synthesis. 3. [texte imprimé] / Seethamraju Srinivas, Auteur ; Ranjan K. Malik, Auteur ; Sanjay M. Mahajani, Auteur . - 2009 . - pp. 4719–4730. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4719–4730 Mots-clés : Reactive  distillation  Multiple  reactant/product  systems  Fischer−Tropsch  Synthesis Résumé : Reactive distillation (RD), a proven reactive separation method that can enhance yields and improve product selectivity in multiple reactant/product systems, was shown to be feasible for FTS in our earlier papers using a simplified kinetics [Srinivas et al. Feasibility of Reactive Distillation for Fischer−Tropsch Synthesis. Ind. Eng. Chem. Res. 2008, 48, 889−899; DOI 10.1021/ie071094p] as well as a detailed kinetics [Srinivas et al. Feasibility of Reactive Distillation for Fischer−Tropsch Synthesis. 2. Ind. Eng. Chem. Res. 2009; DOI 10.1021/ie801887m]. In-built thermodynamic procedures of Aspen Plus, along with a detailed kinetic model that predicts product distribution, were used in performing the simulations. In this paper, we present detailed parametric studies like effect of reflux ratio, H2/CO feed ratio, number of nonreactive stages, etc. Conversion, yield, olefin-to-paraffin ratio and product distribution are the parameters used for comparison among the different cases studied. Within RD mode for FTS, some of the alternate column configurations like those with a side-heat removal and a side-draw, a hybrid column with reactive and nonreactive stages, are also explored and investigated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801888v

Reactive distillation for fischer − tropsch synthesis / Seethamraju Srinivas in Industrial & engineering chemistry research, Vol. 49 N° 20 (Octobre 2010) 

Permalink

Reactive distillation for fischer - tropsch synthesis / Seethamraju Srinivas in Industrial & engineering chemistry research, Vol. 49 N° 14 (Juillet 2010) 

Permalink