Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

A REACTOR WITH CO 2 LASER RADIATION FORDEHYDROGENATION OF LIGHT ALKANES TO ALKENEST.I. Mischenko, Vl.N. Snytnikov, V.N. Snytnikov, I.G. Chernykh*OP-III-20Boreskov Institute of Catalysis SB RAS, Pr. Lavrentieva, 5, 630090, Novosibirsk, RussiaE-mail: mti@catalysis.ru, snyt@catalysis.ru*Institute of Computational Mathematics and Mathematical Geophysics,Pr. Lavrentieva, 6, 630090, Novosibirsk, RussiaE-mail: chernykh@ssd.sscc.ruIntroductionImprovement of the process for ethylene production via dehydrogenation of ethane andother light alkanes in tube furnaces is a topical problem. In tubular reactors [1-3] energy issupplied to reactants by burning a part of hydrocarbon feedstock on the external surface of thetubes. Hot walls of the tubes facilitate not only the formation of radicals, but also their coking.Pyrolysis of ethane is performed in the temperature range of 760 – 820°C with the conversionof 32 – 68% [1]. We propose to create a local zone of elevated temperatures in the tube gaswith the use of laser radiation introduced in the reaction volume. The radiative power shouldbe two orders of magnitude lower than the heat rate coming to reactants from the walls. Theestablishment of such zone of elevated temperature creates the conditions for control over theprocess of pyrolysis. The zone of elevated temperature is a source of radicals for initiating aradical-chain process, which will enable us to reduce temperature of the tube walls anddecrease the dilution ratio. The transformation of CO 2 laser energy to thermal power occurswith the use of ethylene, which is the main product. This will enable the control of pyrolysisvia the generation of radicals in the gas phase by the reaction C 2 H 4 + C 2 H 6 → C 3 H 7 + CH 3 .The lecture presents results of the study on ethylene dehydrogenation in a lab-scale modelreactor with the laser input of energy, and a solution of basic engineering problems arising atheating the reaction mixture components by the laser energy flux delivered directly into thegas.ResultsA particular engineering task is to supply the radiation into reactor with a high powerdensity and prevent its absorption by gas near the windows. Such protection can be providedby a gas flow not absorbing the energy of laser radiation. The FLUENT software programtested with the experimental data of laboratory setup will allow using the numerical methodsto search for the reactor design, which will be further implemented in a prototype reactor.129