Attainable Composition, Energy Consumption, and Entropy Generation Properties for Isothermal/Isobaric Reactor Networks

Abstract

A methodology for the quantification of entropy generation and energy consumption in isothermal, isobaric reactor networks is presented. The proposed methodology employs the Infinite Dimensional State-space (IDEAS) conceptual framework, which is shown to be applicable to the problem under consideration. The IDEAS framework considers all possible reactor units, and all possible mixing and splitting interconnections among them. It will be shown mathematically that, under certain conditions, entropy generation and energy consumption are functions of only the inlet and outlet stream compositions and flow rates and are not dependent on the reactor network structure, as long as there exists a network able to deliver the considered outlets from the known inlets. This theoretical result provides the foundation for a graphical method that can quantify entropy generation and energy consumption, by first identifying the reactor network’s Attainable Region (AR) and then depicting the behavior of the entropy generation and energy consumption functions within the AR. The proposed methodology is demonstrated on a case study featuring reversible reactions both in series and in parallel. Finally, conclusions are drawn.

Infinite DimEnsionAl State-space as a systematic process intensification tool: Energetic intensification of hydrogen production

“…IDEAS has been successfully applied to numerous globally optimal process network synthesis problems, such as mass-exchange network synthesis, 42 complex distillation network synthesis, 30,43 power cycle synthesis, 31 reactor network synthesis, 44,45 reactive distillation network synthesis, 46 separation network synthesis, 47 attainable region construction, 48−51 and batch attainable region construction 52 . More recently, the IDEAS framework has been used to incorporate efficiency considerations, which constitute one of the criteria employed in the expanded definition of process intensification 53 , in reactor network synthesis, by minimizing the network's entropy generation. In particular, it has been shown that the entropy generation and energy consumption of isothermal, isobaric reactor networks only depend on the network's inlet and outlet stream compositions and flow rates, and are independent of the network structure, as long as the universe of realizable reactor/mixer units consists of either only endothermic units, interacting with a single hot reservoir, or only exothermic units interacting with a single cold reservoir, respectively 54 .…”

Minimum entropy generation for isothermal endothermic/exothermic reactor networks

“…This work is a continuation of a previously published contribution by the authors on the synthesis of reactor networks with known entropy generation . In this earlier work, it was rigorously demonstrated, using the Infinite DimEnsionAl State‐space (IDEAS) framework, that if the universe of reactors that could possibly help realize the reactor network consists of either only endothermic reactors or only exothermic reactors, then the quantification of entropy generation and utility consumption can be performed irrespective of the network's internal structure, and depends only on reactor network inlet and outlet compositions.…”

“…First, the network's net (hot minus cold) utility consumption depends only on the network's inlet and outlet stream compositions and flow rates, and does not depend on the network's structure. Therefore, if one is to pursue the synthesis of such reactor networks (isothermal, isobaric, and consisting of reactor/mixer units belonging to a universe that contains both endothermic and exothermic units), using only inlet/outlet stream, and network net utility consumption specifications, then an attainable region‐based synthesis approach, combined with net utility consumption isoclines in the spirit of our earlier work, is feasible to pursue. Indeed, at every point of concentration space that belongs to the attainable region, a unique net utility consumption value can be assigned, as the structure of the networks that deliver this composition outlet (and there can be many such networks) does not affect the value of the net utility consumption at that point in concentration space.…”

Natural-Gas-Derived Hydrogen in the Presence of Carbon Fuel Taxes and Concentrated Solar Power

“…In our earlier work, , we established that a reactor’s heat load may be possible to reduce through the use of a reactor network. In particular, we established theoretically, and demonstrated through case studies, that if the universe of possible reactor networks contains either only endothermic or only exothermic units, then the energy consumption associated with carrying out a particular set of reaction tasks does not depend on the network structure .…”

“…In our earlier work, , we established that a reactor’s heat load may be possible to reduce through the use of a reactor network. In particular, we established theoretically, and demonstrated through case studies, that if the universe of possible reactor networks contains either only endothermic or only exothermic units, then the energy consumption associated with carrying out a particular set of reaction tasks does not depend on the network structure . On the other hand, if the universe of possible reactor networks contains both endothermic and exothermic units, then the energy consumption associated with carrying out a particular set of reaction tasks depends on the network structure, and can be possibly reduced through the use of an appropriate network …”