Carberry

Ethylene oxide catalyst research is expensive and time-consuming because of the need to break in and stabilize the catalyst before rehable data can be collected. Computer controlled tubular microreactors containing as Httle as 5 g of catalyst can be used for assessment of a catalyst s initial performance and for long-term life studies, but moving basket reactors of the Berty (77) or Carberry (78) type are much better suited to kinetic studies. 

H. Heinman and J. J. Carberry, eds.. Catalysis Eeviews—Science and Engineering, Vol. 26, Marcel-Dekker, New York, 1984. 

Carberry, Chemical and Catalytic Reaction Engineeting, McGraw-Hill, 1976. 

Carberry and Varma (eds.). Chemical Reaction and Reactor Engineeting, Dekker, 1987. 

For complex reac tions and with multistage CSTRs, more than three steady states can exist (as in Fig. 23-17c). Most of the work on multi-phcities and instabilities has been done only on paper. No plant studies and a very few laboratoiy studies are mentioned in the comprehensive reviews of Razon and Schmitz Chem. Eng. Sci., 42, 1,005-1,047 [1987]) and Morbidelli et al. (in Carberry and Varma, Chemical Reaction and Reactor Engineering, Dekker, 1987, pp. 973-1,054). 

Dente and Ranzi (in Albright et al., eds.. Pyrolysis Theory and Industrial Practice, Academic Press, 1983, pp. 133-175) Mathematical modehng of hydrocarbon pyrolysis reactions Shah and Sharma (in Carberry and Varma, eds.. Chemical Reaction and Reaction Engineering Handbook, Dekker, 1987, pp. 713-721) Hydroxylamine phosphate manufacture in a slurry reactor Some aspects of a kinetic model of methanol synthesis are described in the first example, which is followed by a second example that describes coping with the multiphcity of reactants and reactions of some petroleum conversion processes. Then two somewhat simph-fied industrial examples are worked out in detail mild thermal cracking and production of styrene. Even these calculations are impractical without a computer. The basic data and mathematics and some of the results are presented. 

Many authors contributed to the field of diffusion and chemical reaction. Crank (1975) dealt with the mathematics of diffusion, as did Frank-Kamenetskii (1961), and Aris (1975). The book of Sherwood and Satterfield (1963) and later Satterfield (1970) discussed the theme in detail. Most of the published papers deal with a single reaction case, but this has limited practical significance. In the 1960s, when the subject was in vogue, hundreds of papers were presented on this subject. A fraction of the presented papers dealt with the selectivity problem as influenced by diffitsion. This field was reviewed by Carberry (1976). Mears (1971) developed criteria for important practical cases. Most books on reaction engineering give a good summary of the literature and the important aspects of the interaction of diffusion and reaction. 

In moving catalyst basket reactors, the flow regime is ill-defined and the contact between catalyst and gas can be poor even if well-mixed conditions for the fluid phase are achieved. Perhaps the most successful representative of this category is the Carberry reactor (1964, 1966). Even in this model only a single layer of catalyst can be charged in the cruciform catalyst basket because the fluid flows in a radial direction outward and... 

In summary, external recycle reactors are expensive and their usefulness is limited. They can be practical for simple chemical systems where no condensation can occur and neither high pressure nor high temperature is needed. For example Carberry et al (1980) preferred an external recycle reactor over a spinning basket reactor for the study of CO oxidation in dry air at atmospheric pressure. 

To estimate the average gradient, the concentration difference should be divided by the unknown boundary layer depth 5. While this is unknown, the Carberry number (Ca) gives a direct estimate of what concentration fraction drives the transfer rate. The concentration difference tells the concentration at which the reaction is really running. 

Here Iq is the thermal conductivity of the system, consisting of the porous solid and the reacting fluid inside the pores. This is the most uncertain value, while everything else is measurable. Two things must be remembered. First, data on thermal conductivity of catalysts are approximate. The solid fraction of the catalyst (1-0) always reduces the possibility for diflhision, while the solid can contribute to the thermal conductivity. Second, the outside temperature difference normal to the surface or Daiv, will become too high, much before the inside gradient can cause a problem. See Hutching and Carberry (19), Carberry (20). 

Carra and Forni (1974) derived the criteria that Carberry (1976) referred to in his book. These are equivalent to the original derivation of Aris and Amundson (1958). The notation is easier to understand and closer to the notation in this book. Eliminating some typographical errors, the criteria are ... 

Carberry, J.J., 1976, Chemical and Catalytic Reaction Engineering, McGraw-Hill, Inc., New York. 

Page 3 gives a summary of the most important result in a figure illustrating in a semi-quantitative way the conditions in the specified CSTR. As can be seen on line 74, Dar is somewhat larger than the critical value but the concentration difference on line 75 is small, so this result can be accepted with some reservations. The Carberry number is also larger than the criteria, therefore these experimental results are marginal for Nox abatement... 

The unnamed number C is now called the Carberry number, and D is identical with Daiv-=Dav. 

After the rates have been determined at a series of reactant concentrations, the differential method of testing rate equations is applied. Smith [3] and Carberry [4] have adequately reviewed the designs of heterogeneous catalytic reactors. The following examples review design problems in a plug flow reactor with a homogeneous phase. 

Shinnar, R., Use of Residence and Contact Time Distributions in Reactor Design, Chapter 2, pp. 63-149 of Chemical Reaction and Reactor Engineering, Carberry, J. J. and Varma, A., Eds., Marcel Dekker, New York, 1987. 

There is no striet proeedure for seale-up of a ehemieal reaetor by matliematieal modeling. Himmelblau [4] has reviewed the mathe-matieal modeling approaeh, and otliers speeifie examples are expatiated by Rase [5] and Carberry [6]. The following deseribe the steps applied to a seale-up problem as they relate to a eatalytie reaetor having a fixed bed of solid eatalysts. 

Chemical Reaction and Reactor Engineering, edited by J. J. Carberry and A. Varma... 

The kinetics of a mixed platinum and base metal oxide catalyst should have complementary features, and would avoid some of the reactor instability problems here. The only stirred tank reactor for a solid-gas reaction is the whirling basket reactor of Carberry, and is not adaptable for automotive use (84) A very shallow pellet bed and a recycle reactor may approach the stirred tank reactor sufficiently to offer some interest. 

A variety of models of chemical reactors is discussed in more detail in Section 5.4. Readers who are interested in modelling of chemical reactors are also referred to books of Carberry and Varma (1987), Fogler (1986), Froment and Bischoff (1990), Levenspiel (1999), Smith (1981), Trambouze et al. (1988), Walas (1959), and Westerterp et al. (1990). With respect to heterogeneous reactions athe book of Doraiswamy and Sharma (1984) is also recommended. 

Figure 5.4-20. Basket-type reactor (Carberry reactor).

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