Pyrolysis model, tubular

Hirato, M., Yoshioka, S., and M. Tanaka, Gas Oil Pyrolysis by Tubular Reactor and its Simulation Model of Reaction, Hitachi Review 20 8,326,1971. 

For some widely practiced processes, especially in the petroleum industry, reliable and convenient computerized models are available from a number of vendors or, by license, from proprietary sources. Included are reactor-regenerator of fluid catalytic cracking, hydro-treating, hydrocracking, alkylation with HF or H2SO4, reforming with Pt or Pt-Re catalysts, tubular steam cracking of hydrocarbon fractions, noncatalytic pyrolysis to ethylene, ammonia synthesis, and other processes by suppliers of catalysts. Vendors of some process simulations are listed in the CEP Software Directory (AIChE, 1994). 

It should be noted that Equations 1, 2, 3, 4, and 5 imply a homogeneous kinetic system. Coking in tubular reactors results from a combination of homogeneous and heterogeneous processes. As the kinetics of these processes are not well understood and as the quantitative yield of coke is several orders of magnitude smaller than other pyrolysis products, it is more convenient to model coke formation separately based on commercial operating data. 

Diebold, J. P. (1985) The Cracking Kinetics of Depoiymerized Biomass Vapors in a Continuous, Tubular Reactor. M. S. Thesis, Dept, of Chemical and Petroleum-Refining Engineering, Colorado School of Mines, Golden, Colorado. Liden, A. G. (1985) A Kinetic and Heat Transfer Modelling Study of Wood Pyrolysis in a Fluidized Bed. MASc Thesis, Dept, of Chemical Engineering, University of Waterloo. 

This reaction has been studied using batch reactors, perfectly stirred continuous reactors, tubular continuous reactors, BENSON type reactors, wall-less reactors and shock tubes. The reaction has been carried out at temperatures between 700 and 1300 K, at pressures of 0.1 Pa to 10 Pa and at reaction times of 10 s to 10 s. The effects of the nature and of the area of the reactor walls as well as those of various additives have also been studied. The diversity of the studies carried out by a dozen teams throughout the world, the particularly widespread range of operating conditions (600 K for the temperature, which represents 11 orders of magnitude for the rate of initiation, 8 orders of magnitude for the pressure and reaction duration) make the pyrolysis of neopentane into a model radical reaction. 

Abstract. Pyrolysis of 1-butene and cis-2-butene was studied in a gold, tubular reactor over the temperature range of 530 to 620 C and at a total pressure of 1 atmosphere. Argon was used as a diluent. Mole fractions of the butenes ranged from 0.06 to 0.9 mole percent. Reaction models were established and reasonable agreement with experiment observed. 

Based on naphtha pyrolysis experiments conducted in a bench scale tubular reactor (suitable for the simulation of industrial tubular furnace operations and taking into account the changes of expansion, temperature and the pressure in the reactor), a kinetic model has been developed for the calculation of the degree of de-con osition, the actual residence time, and the severHy of cracking. 

In none of these samples was it possible to find structures that were comparable with the structures previously published by other authors [35]. In their investigations, carbon black was liberated from the matrix by solution and subsequent filtration. In contrast, we find different structures that support the assumption of a concentration of the carbon black in layers. The structures found after pyrolysis by studies with the scanning electron microscope may be flat (Fig. 19.33), wavelike, tubular, or foamlike (Fig. 19.34). These observations can be interpreted with the aid of the model of an interpenetrating network of layers with different structures, as has already been proposed in Ref. 36. 

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