The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Wim P.m. Van Swaaij - One of the best experts on this subject based on the ideXlab platform.
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A novel reverse flow reactor coupling Endothermic and exothermic reactions. Part II: Sequential reactor configuration for reversible Endothermic reactions
Chemical Engineering Science, 2002Co-Authors: H. A R Scholts, Martin Van Sint Annaland, Wim P.m. Van Swaaij, Johannes A.m. KuipersAbstract:The new reactor concept for highly Endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of Endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible Endothermic reactions for the sequential reactor configuration. In the sequential reactor configuration, the Endothermic and exothermic reactants are fed discontinuously and sequentially to the same catalyst bed, which acts as an energy repository delivering energy during the Endothermic reaction phase and storing energy during the consecutive exothermic reaction phase. The periodic flow reversals to incorporate recuperative heat exchange result in low temperatures at both reactor ends, while high temperatures prevail in the centre of the reactor. For reversible Endothermic reactions, these low exit temperatures can shift the equilibrium back towards the reactants side, causing 'back-conversion' at the reactor outlet. The extent of back-conversion is investigated for the propane dehydrogenation/methane combustion reaction system, considering a worst case scenario for the kinetics by assuming that the propylene hydrogenation reaction rate at low temperatures is only limited by mass transfer. It is shown for this reaction system that full equilibrium conversion of the Endothermic reactants cannot be combined with recuperative heat exchange, if the reactor is filled entirely with active catalyst. Inactive sections installed at the reactor ends can reduce this back-conversion, but cannot completely prevent it. Furthermore, undesired high temperature peaks can be formed at the transition point between the inactive and active sections, exceeding the maximum allowable temperature (at least for the relatively fast combustion reactions). A new solution is introduced to achieve both full equilibrium conversion and recuperative heat exchange while simultaneously avoiding too high temperatures, even for the worst case scenario of very fast propylene hydrogenation and fuel combustion reaction rates. The proposed solution utilises the movement of the temperature fronts in the sequential reactor configuration and employs less active sections installed at either end of the active catalyst bed and completely inactive sections at the reactor ends, whereas propane combustion is used for energy supply. Finally, it is shown that the plateau temperature can be effectively controlled by simultaneous combustion of propane and methane during the exothermic reaction phase. ?? 2002 Elsevier Science Ltd. All rights reserved.
M P Dudukovic - One of the best experts on this subject based on the ideXlab platform.
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coupling exothermic and Endothermic reactions in adiabatic reactors
Chemical Engineering Science, 2008Co-Authors: R C Ramaswamy, P A Ramachandran, M P DudukovicAbstract:Abstract The steady state and the dynamic behavior of coupling exothermic and Endothermic reactions in directly coupled adiabatic packed bed reactors (DCAR) are analyzed using one-dimensional pseudo-homogeneous plug flow model. Two different configurations of DCAR (simultaneous DCAR—SIMDCAR and sequential DCAR—SEQDCAR) are investigated. In SIMDCAR, the catalyst bed favors both exothermic and Endothermic reactions and both reactions occur simultaneously. SEQDCAR has alternating layers of catalyst beds for exothermic and Endothermic reactions and hence the exothermic and Endothermic reactions occur in a sequential fashion. The performance of both reactors, in terms of conversion achieved and manifested hot spot behavior, is compared with that of the co-current heat exchanger type reactor. Various possible operational regimes in SIMDCAR have been classified and the conditions for the existence of hot spots or cold spots in SIMDCAR are obtained analytically for the first order reactions with equal activation energies. The reactor behavior for the reactions with non-equal activation energies is also presented. The preliminary criteria for the selection of suitable reactor type and the general bounds on the reaction parameters to obtain the desired conversion for Endothermic reaction with minimal temperature rise are proposed. The dynamic behavior of these reactors is important for control applications and we have reported some of the transient behavior.
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recuperative coupling of exothermic and Endothermic reactions
Chemical Engineering Science, 2006Co-Authors: R C Ramaswamy, P A Ramachandran, M P DudukovicAbstract:Coupling energy intensive Endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the size of the reactors. One type of reactor suitable for such a type of coupling is the heat exchanger reactor. In this work, a one-dimensional pseudo-homogeneous plug flow model is used to analyze and compare the performance of co-current and counter-current heat exchanger reactors. A parametric analysis is carried out to address the vital issues, such as the exit conversion of the Endothermic reaction, the temperature peak (hot spot) of the exothermic reaction and the reactor volumetric productivity. The measures to reduce the hot spot by different catalyst profiling techniques are also addressed. Some features of the dynamic behavior exhibited by these reactors, which are important from design, operational and control point of view, are presented.
Martin Van Sint Annaland - One of the best experts on this subject based on the ideXlab platform.
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A novel reverse flow reactor coupling Endothermic and exothermic reactions. Part II: Sequential reactor configuration for reversible Endothermic reactions
Chemical Engineering Science, 2002Co-Authors: H. A R Scholts, Martin Van Sint Annaland, Wim P.m. Van Swaaij, Johannes A.m. KuipersAbstract:The new reactor concept for highly Endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of Endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible Endothermic reactions for the sequential reactor configuration. In the sequential reactor configuration, the Endothermic and exothermic reactants are fed discontinuously and sequentially to the same catalyst bed, which acts as an energy repository delivering energy during the Endothermic reaction phase and storing energy during the consecutive exothermic reaction phase. The periodic flow reversals to incorporate recuperative heat exchange result in low temperatures at both reactor ends, while high temperatures prevail in the centre of the reactor. For reversible Endothermic reactions, these low exit temperatures can shift the equilibrium back towards the reactants side, causing 'back-conversion' at the reactor outlet. The extent of back-conversion is investigated for the propane dehydrogenation/methane combustion reaction system, considering a worst case scenario for the kinetics by assuming that the propylene hydrogenation reaction rate at low temperatures is only limited by mass transfer. It is shown for this reaction system that full equilibrium conversion of the Endothermic reactants cannot be combined with recuperative heat exchange, if the reactor is filled entirely with active catalyst. Inactive sections installed at the reactor ends can reduce this back-conversion, but cannot completely prevent it. Furthermore, undesired high temperature peaks can be formed at the transition point between the inactive and active sections, exceeding the maximum allowable temperature (at least for the relatively fast combustion reactions). A new solution is introduced to achieve both full equilibrium conversion and recuperative heat exchange while simultaneously avoiding too high temperatures, even for the worst case scenario of very fast propylene hydrogenation and fuel combustion reaction rates. The proposed solution utilises the movement of the temperature fronts in the sequential reactor configuration and employs less active sections installed at either end of the active catalyst bed and completely inactive sections at the reactor ends, whereas propane combustion is used for energy supply. Finally, it is shown that the plateau temperature can be effectively controlled by simultaneous combustion of propane and methane during the exothermic reaction phase. ?? 2002 Elsevier Science Ltd. All rights reserved.
H. A R Scholts - One of the best experts on this subject based on the ideXlab platform.
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A novel reverse flow reactor coupling Endothermic and exothermic reactions. Part II: sequential reactor configuration for reversible Endothermic reactions
Chemical Engineering Science, 2002Co-Authors: Van M Martin Sint Annaland, H. A R Scholts, Jam Hans Kuipers, Van Wpm Wim SwaaijAbstract:The new reactor concept for highly Endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of Endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible Endothermic reactions for the sequential reactor configuration. In the sequential reactor configuration, the Endothermic and exothermic reactants are fed discontinuously and sequentially to the same catalyst bed, which acts as an energy repository delivering energy during the Endothermic reaction phase and storing energy during the consecutive exothermic reaction phase. The periodic flow reversals to incorporate recuperative heat exchange result in low temperatures at both reactor ends, while high temperatures prevail in the centre of the reactor. For reversible Endothermic reactions, these low exit temperatures can shift the equilibrium back towards the reactants side, causing ‘back-conversion’ at the reactor outlet. The extent of back-conversion is investigated for the propane dehydrogenation/methane combustion reaction system, considering a worst case scenario for the kinetics by assuming that the propylene hydrogenation reaction rate at low temperatures is only limited by mass transfer. It is shown for this reaction system that full equilibrium conversion of the Endothermic reactants cannot be combined with recuperative heat exchange, if the reactor is filled entirely with active catalyst. Inactive sections installed at the reactor ends can reduce this back-conversion, but cannot completely prevent it. Furthermore, undesired high temperature peaks can be formed at the transition point between the inactive and active sections, exceeding the maximum allowable temperature (at least for the relatively fast combustion reactions). A new solution is introduced to achieve both full equilibrium conversion and recuperative heat exchange while simultaneously avoiding too high temperatures, even for the worst case scenario of very fast propylene hydrogenation and fuel combustion reaction rates. The proposed solution utilises the movement of the temperature fronts in the sequential reactor configuration and employs less active sections installed at either end of the active catalyst bed and completely inactive sections at the reactor ends, whereas propane combustion is used for energy supply. Finally, it is shown that the plateau temperature can be effectively controlled by simultaneous combustion of propane and methane during the exothermic reaction phase.
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A novel reverse flow reactor coupling Endothermic and exothermic reactions. Part I: comparison of reactor configurations for irreversible Endothermic reactions
Chemical Engineering Science, 2002Co-Authors: Van M Martin Sint Annaland, H. A R Scholts, Jam Hans Kuipers, Van Wpm Wim SwaaijAbstract:A new reactor concept is studied for highly Endothermic heterogeneously catalysed gas phase reactions at high temperatures with rapid but reversible catalyst deactivation. The reactor concept aims to achieve an indirect coupling of energy necessary for Endothermic reactions and energy released by exothermic reactions, without mixing of the Endothermic and exothermic reactants, in closed-loop reverse flow operation. Periodic gas flow reversal incorporates regenerative heat exchange inside the reactor. The reactor concept is studied for the coupling between the non-oxidative propane dehydrogenation and methane combustion over a monolithic catalyst. Two different reactor configurations are considered: the sequential reactor configuration, where the Endothermic and exothermic reactants are fed sequentially to the same catalyst bed acting as an energy repository and the simultaneous reactor configuration, where the Endothermic and exothermic reactants are fed continuously to two different compartments directly exchanging energy. The dynamic reactor behaviour is studied by detailed simulation for both reactor configurations. Energy constraints, relating the Endothermic and exothermic operating conditions, to achieve a cyclic steady state are discussed. Furthermore, it is indicated how the operating conditions should be matched in order to control the maximum temperature. Also, it is shown that for a single first order exothermic reaction the maximum dimensionless temperature in reverse flow reactors depends on a single dimensionless number. Finally, both reactor configurations are compared based on their operating conditions. It is shown that only in the sequential reactor configuration the Endothermic inlet concentration can be optimised independently of the gas velocities at high throughput and maximum reaction coupling energy efficiency, by the choice of a proper switching scheme with inherently zero differential creep velocity and using the ratio of the cycle times. In this first part, both the propane dehydrogenation and the methane combustion have been considered as first order irreversible reactions. However, the propane dehydrogenation is an equilibrium reaction and the low exit temperatures resulting from the reverse flow concept entail considerable propane conversion losses. How this `back-conversion? can be counteracted is discussed in part II Chemical Engineering Science, 57, (2002), 855?872.
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A novel reverse flow reactor coupling Endothermic and exothermic reactions. Part II: Sequential reactor configuration for reversible Endothermic reactions
Chemical Engineering Science, 2002Co-Authors: H. A R Scholts, Martin Van Sint Annaland, Wim P.m. Van Swaaij, Johannes A.m. KuipersAbstract:The new reactor concept for highly Endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of Endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible Endothermic reactions for the sequential reactor configuration. In the sequential reactor configuration, the Endothermic and exothermic reactants are fed discontinuously and sequentially to the same catalyst bed, which acts as an energy repository delivering energy during the Endothermic reaction phase and storing energy during the consecutive exothermic reaction phase. The periodic flow reversals to incorporate recuperative heat exchange result in low temperatures at both reactor ends, while high temperatures prevail in the centre of the reactor. For reversible Endothermic reactions, these low exit temperatures can shift the equilibrium back towards the reactants side, causing 'back-conversion' at the reactor outlet. The extent of back-conversion is investigated for the propane dehydrogenation/methane combustion reaction system, considering a worst case scenario for the kinetics by assuming that the propylene hydrogenation reaction rate at low temperatures is only limited by mass transfer. It is shown for this reaction system that full equilibrium conversion of the Endothermic reactants cannot be combined with recuperative heat exchange, if the reactor is filled entirely with active catalyst. Inactive sections installed at the reactor ends can reduce this back-conversion, but cannot completely prevent it. Furthermore, undesired high temperature peaks can be formed at the transition point between the inactive and active sections, exceeding the maximum allowable temperature (at least for the relatively fast combustion reactions). A new solution is introduced to achieve both full equilibrium conversion and recuperative heat exchange while simultaneously avoiding too high temperatures, even for the worst case scenario of very fast propylene hydrogenation and fuel combustion reaction rates. The proposed solution utilises the movement of the temperature fronts in the sequential reactor configuration and employs less active sections installed at either end of the active catalyst bed and completely inactive sections at the reactor ends, whereas propane combustion is used for energy supply. Finally, it is shown that the plateau temperature can be effectively controlled by simultaneous combustion of propane and methane during the exothermic reaction phase. ?? 2002 Elsevier Science Ltd. All rights reserved.
Johannes A.m. Kuipers - One of the best experts on this subject based on the ideXlab platform.
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A novel reverse flow reactor coupling Endothermic and exothermic reactions. Part II: Sequential reactor configuration for reversible Endothermic reactions
Chemical Engineering Science, 2002Co-Authors: H. A R Scholts, Martin Van Sint Annaland, Wim P.m. Van Swaaij, Johannes A.m. KuipersAbstract:The new reactor concept for highly Endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of Endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible Endothermic reactions for the sequential reactor configuration. In the sequential reactor configuration, the Endothermic and exothermic reactants are fed discontinuously and sequentially to the same catalyst bed, which acts as an energy repository delivering energy during the Endothermic reaction phase and storing energy during the consecutive exothermic reaction phase. The periodic flow reversals to incorporate recuperative heat exchange result in low temperatures at both reactor ends, while high temperatures prevail in the centre of the reactor. For reversible Endothermic reactions, these low exit temperatures can shift the equilibrium back towards the reactants side, causing 'back-conversion' at the reactor outlet. The extent of back-conversion is investigated for the propane dehydrogenation/methane combustion reaction system, considering a worst case scenario for the kinetics by assuming that the propylene hydrogenation reaction rate at low temperatures is only limited by mass transfer. It is shown for this reaction system that full equilibrium conversion of the Endothermic reactants cannot be combined with recuperative heat exchange, if the reactor is filled entirely with active catalyst. Inactive sections installed at the reactor ends can reduce this back-conversion, but cannot completely prevent it. Furthermore, undesired high temperature peaks can be formed at the transition point between the inactive and active sections, exceeding the maximum allowable temperature (at least for the relatively fast combustion reactions). A new solution is introduced to achieve both full equilibrium conversion and recuperative heat exchange while simultaneously avoiding too high temperatures, even for the worst case scenario of very fast propylene hydrogenation and fuel combustion reaction rates. The proposed solution utilises the movement of the temperature fronts in the sequential reactor configuration and employs less active sections installed at either end of the active catalyst bed and completely inactive sections at the reactor ends, whereas propane combustion is used for energy supply. Finally, it is shown that the plateau temperature can be effectively controlled by simultaneous combustion of propane and methane during the exothermic reaction phase. ?? 2002 Elsevier Science Ltd. All rights reserved.