Methane Conversion to Ethylene and Acetylene:  Optimal Control with Chlorine, Oxygen, and Heat Flux

Abstract

In this paper, an optimal control strategy is applied to the problem of finding the flux profiles for the conversion of methane to ethylene and acetylene in a plug flow reactor. A chlorinecatalyzed oxidative pyrolysis mechanism is used in the calculations, in which two mechanistic pathways to the C 2 products were examined. One involves CH 3 Cl and/or CH 2 Cl, and the other involves C 2 H 6 and/or C 2 H 5 as reaction intermediates. Optimal control designs were performed with respect to the final mass fractions of ethylene and acetylene in a plug flow reactor using heat, oxygen, and chlorine fluxes as controls. The simulation results show that for the temperatures (1200 K < T < 1900 K) and pressure (P ) 1 atm) considered, C 2 H 4 is formed initially, which is subsequently converted to C 2 H 2 . Because of the abundant supply of H 2 formed during the reaction, it is possible to reform C 2 H 4 from C 2 H 2 by controlled extraction of energy. The heat flux plays the most important role in determining the final concentration of the desired C 2 products by controlling the temperature and the rate of H-atom radical generation, and thus, the interconversion between C 2 H 2 and C 2 H 4 through the C 2 H 3 radical. The solutions obtained, although not proven to be globally optimal, are of very high quality. More than 40% yield of the desired C 2 products, either ethylene or acetylene, can be obtained in all cases.

Investigation on Evolutionary Computation Techniques of a Nonlinear System

“…Applications presented in this area include the work by Balakrishna and Biegler [31,32] and Lakshmanan and Biegler [33][34][35] and involved mathematical programming applications in the form of NLP and MINLP formulations. Optimal control formulation has been presented by Rojnuckarin et al [36] and Schweiger and Floudas [37]. Hildebrandt and Biegler [38] presented a review of the attainable region approaches and suggested areas for future development of the concept.…”

Optimization of polymer synthesis through distributed control of polymerization conditions

“…The computer code employed for these simulations has performed well in previous applications. 6,13,14 It is important to note that this work serves to show the general significance of optimally controlling polymer synthesis rather than attempting to corroborate any specific reaction mechanism or experiment.…”

Optimization of Living Radical Polymerization Through Distributed Control of Energy

“…T 0 is the temperature of the influxed species. The optimal control methodology is described in Rojnuckarin et al [10] In the calculations, the CONMIN [11] code was used as the conjugate gradient minimizer; the chemical kinetics package CHEMKIN-II [12] was employed to interface the thermodynamic and kinetics data, and LSODA [13] was used as a differential equation integrator.…”

“…The computer code employed for these simulations has performed well in previous applications. [9,10,22] It is important to note that the present work serves to show the general significance of optimally controlling polymer synthesis rather than attempting to corroborate any specific reaction mechanism or experiment.…”

“…A tubular plug flow reactor (PFR) is a good platform for this modeling study, because the energy flux can be readily distributed along the side of the reactor. [9] By applying a previously developed optimal control methodology, [9,10] energy flux is optimized to produce a polymer of desired average molecular weight, with as narrow a molecular weight distribution as possible, while maintaining the highest possible conversion.…”