Showing papers by "Preeti Aghalayam published in 2006"
TL;DR: In this article, the gasification channel is viewed as a one-dimensional packed bed reactor and a pseudo-transient model is simulated for temperature and composition profiles of the gas and solid phases.
Abstract: Underground Coal Gasification (UCG) is the process of in-situ conversion of coal into combustible products (syngas) which can be used either as fuel or as a chemical feedstock. In this study, the gasification channel is viewed as a one-dimensional packed bed reactor. The packed bed reactor model is solved incorporating chemical reactions and mass transfer effects. A pseudo-transient model is simulated for temperature and composition profiles of the gas and solid phases. The movements of the pyrolysis and the reaction front are obtained. The model results are in qualitative agreement with literature. The effects of various operating parameters are studied in detail. Steam/O2 ratio, inlet O2 and total pressure determine the solid temperature profile and hence the outlet gas composition. The simulations are performed for two sets of kinetics parameters. The solid temperature profile and outlet gas compositions change significantly with a change in kinetics parameters. The main motivation behind this study is to provide a theoretical base for understanding the critical aspects of UCG and to provide a tool which coupled with experiments will help in determining the commercial feasibility of the UCG process.
43 citations
TL;DR: In this paper, a batch reaction of isobutene was carried out in a batch reactor over a temperature range of 65−95 °C in the presence of ion-exchange resin as a catalyst and isooctane as a solvent.
Abstract: The dimerization of isobutene (IB) followed by hydrogenation is looked upon as an important route to produce the octane booster isooctane (IO), because of doubts being raised about methyl tert-butyl ether (MTBE) being a clean fuel additive because of its substantial solubility in water. In the present work, the dimerization of IB has been carried out in a batch reactor over a temperature range of 65−95 °C in the presence of ion-exchange resin as a catalyst and isooctane as a solvent. The influence of various parameters such as temperature, catalyst loading, concentration of water, and initial concentration of IB was examined. Because several side reactions are involved in this reacting system, the selectivity of IB toward the dimers is an important issue. The presence of a polar compound in the reaction mixture plays a vital role as an inhibitor to the side reactions and improves the selectivity toward the dimers. In the present system, water was used as an inhibitor, which leads to the formation of tert-...
32 citations
TL;DR: In this article, the influence of important design and operating parameters on the performance of the reaction in a hybrid reactive distillation column is studied through process simulations, and the results show that a high selectivity toward diisobutene can be achieved along with adequate temperature control in the presence as well as absence of polar components.
Abstract: Alkylates are a class of probable replacements for MTBE as gasoline additives that can be produced by dimerization of isobutene (to isooctene) with subsequent hydrogenation. The characteristics of the dimerization reaction make it a potential candidate for reactive distillation. The dimer, being heavier than C4, can be maintained at a low concentration level in the reactive zone by simultaneous distillation, thereby suppressing the subsequent oligomer-producing reactions. In this work, the influence of important design and operating parameters on the performance of the reaction in a hybrid reactive distillation column is studied through process simulations. the results show that a high selectivity toward diisobutene can be achieved along with adequate temperature control in the presence as well as absence of polar components. Multiple steady states are observed in some cases that introduce additional complexities in the determination of the optimal windows for certain parameters. The process seems economi...
30 citations
TL;DR: In this paper, a comparison of reactive distillation and conventional multi-unit structures for the isobutene dimerization reaction was made using a single reaction-separation network with and without recycle.
Abstract: Reactive distillation is an attractive alternative to conventional multiunit structures. In the case of irreversible reactions involving several products, reactive distillation may effectively improve the selectivity toward a desired intermediate product. However, multiunit processes for such reactions cannot be simply discounted without a systematic comparison with reactive distillation. This work emphasizes such a comparison using the isobutene dimerization reaction as an example. The multiunit configurations considered include the conventional reaction-separation network with and without recycle and a distillation column coupled with a side reactor. Potential configurations of process alternatives are generated for a wide range of the conversion of isobutene and the alternatives are compared on the basis of the selectivity toward diisobutene achieved and cost incurred for identical isobutene conversion. Results show that, for a given isobutene conversion, the reactive distillation process is capable of...
11 citations