Explicit runaway criterion for catalytic reactors with transport limitations

Balakotaiah, Vemuri; Luss, Dan

doi:10.1002/aic.690371203

Cited by 27 publications

(11 citation statements)

References 17 publications

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“…Bilous and Amundsen6 were the first authors to describe that phenomenon in tubular reactors. Contributions in this field are ascribed to Dente and Collina,7 Hlavacek et al,8 Van Welsenaere and Froment,9 Morbidelli and Varma,10 Hugo,11 and Balakotaiah and Luss12 among others.…”

Section: Introductionmentioning

confidence: 99%

Selective inhibition of cyclooxygenase 2–generated prostaglandin E₂ synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Kontny¹,

Rudnicka²,

Kowalczewski³

et al. 2003

Arthritis & Rheumatism

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Objective. To investigate the effects of taurine chloramine (Tau-Cl), a chlorinated derivative of the amino acid taurine, on the expression of cyclooxygenase (COX) isoenzymes and prostaglandin E 2 (PGE 2 ) synthesis in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS).Methods. FLS, isolated from the synovial tissue of RA patients, were treated in vitro with either interleukin-1␤ (IL-1␤; 1 ng/ml) alone or together with 200-500 M Tau-Cl. The expression of COX isoenzymes was evaluated at both the protein (Western blotting) and the messenger RNA (mRNA) (reverse transcriptase-polymerase chain reaction) levels. The concentration of PGE 2 was measured by competitive acetylcholinesterase enzyme immunoassay.Results. Resting FLS expressed mRNA encoding both COX-1 and COX-2, but only COX-1 was present at the protein level. These cells produced negligible amounts of PGE 2 . Upon stimulation with IL-1␤, elevation of COX-2, but not COX-1, mRNA and protein preceded the enhancement of PGE 2 synthesis. In the presence of 300-400 M Tau-Cl, significant inhibition of IL-1␤-triggered COX-2 mRNA and protein, and a related decrease in PGE 2 production, was observed. In contrast, no significant changes in COX-1 mRNA and protein levels were noted.Conclusion. Tau-Cl inhibits IL-1␤-triggered elevation of COX-2 and generation of PGE 2 by RA FLS. These results expand the spectrum of known antiinflammatory activities of this compound.

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Section: Introductionmentioning

confidence: 99%

Selective inhibition of cyclooxygenase 2–generated prostaglandin E₂ synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Kontny¹,

Rudnicka²,

Kowalczewski³

et al. 2003

Arthritis & Rheumatism

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“…The heat transfer capacity of the reactor (at t ϭ 0) is defined as (12) and the cooling capacity arising from the inlet stream, colder in general than the reacting mixture, is…”

Section: Sbr Equations For the Feed Stage (T < T D )mentioning

confidence: 99%

Safe operation of stirred‐tank semibatch reactors subject to risk of thermal hazard

et al. 2006

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In this work, the behavior of exothermic chemical reactions conducted in a wall-cooled, semibatch stirred-tank reactor is studied, with particular attention to conditions that lead to a thermal accident. The dimensionless heat and mass conservation equations for a semicontinuous tank were solved using second-order irreversible kinetics and a number of selected dimensionless numbers, for both the feed period and the late batch stage. The criterion implemented is based on the nonaccumulation of the dosed reactant, and the safest operating mode is based on the values of the reactor parameters that lead to an instantaneous consumption of the dosed feed. The criterion is implemented into an algorithm that runs in parallel with the integration of the model equations. Its applicability is shown using a few examples that show that the computer implementation of our methods works well in hazard prediction.

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“…Transport phenomena are as important as the catalytic properties in evaluating the efficiency and selectivity of a catalytic reactor. Consequently, the packed catalyst reactor bed has been the subject of a large number of theoretical and experimental investigations (Aris, 1969;Hugo, 1971;Wicke et al, 1971;Balakotaiah and Luss, 1991;Philippou et al, 1993). The emphasis in the work of those researchers has been put on the steady-state multiplicity of catalytic reactors, and the operating conditions where such multiplicity may OCcur.…”

Section: Catalyst Pelletmentioning

confidence: 99%

Reaction invariance and stability in catalyst particles for production of Methanol

Asbjørnsen

Hillestad

1997

AIChE Journal

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Industrial practice requires immediate and adequate responses to simple questions asked. For example, does a catalyst particle show any tendency to thermal oscillations in the form of a limit cycle? The root to such cycles is found in the eigenvalues of the Jacobian matrix to the reaction rate vector, applying the concept of reaction invariance, a direct consequence of Avogadro ' s stoichiometric principle for homogeneous stirred tank reactors. However, this concept does not generally apply to heterogeneous reactor dynamics, because it is found in the heterogeneous transports of heat, reactants and products. The transport is an irreversible phenomenon that usually contributes to shifting the eigenvalues to the left and hence increases the stabiliy. Still, effects of transport mechanisms, both internally and externally, on the catalyst particle are important to assess in such industrial analyses. A practical industrial reactor for methanol production was the subject for stability studies, which concluded that thermal oscillations are not likely to occur. During this study, a number of interesting details were examined such as rank deficiency of the reaction matrix and root loci for the temperature dependence of the Jacobian matrix eigenvalues. A practical consequence of eventual thermal cycling of the catalyst particles is a long-term degradation of the catalyst eficiency, as seen in the ammonia synthesis.

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Explicit runaway criterion for catalytic reactors with transport limitations

Cited by 27 publications

References 17 publications

Selective inhibition of cyclooxygenase 2–generated prostaglandin E₂ synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Selective inhibition of cyclooxygenase 2–generated prostaglandin E₂ synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Safe operation of stirred‐tank semibatch reactors subject to risk of thermal hazard

Reaction invariance and stability in catalyst particles for production of Methanol

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Explicit runaway criterion for catalytic reactors with transport limitations

Cited by 27 publications

References 17 publications

Selective inhibition of cyclooxygenase 2–generated prostaglandin E2 synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Selective inhibition of cyclooxygenase 2–generated prostaglandin E2 synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Safe operation of stirred‐tank semibatch reactors subject to risk of thermal hazard

Reaction invariance and stability in catalyst particles for production of Methanol

Contact Info

Product

Resources

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Selective inhibition of cyclooxygenase 2–generated prostaglandin E₂ synthesis in rheumatoid arthritis synoviocytes by taurine chloramine

Selective inhibition of cyclooxygenase 2–generated prostaglandin E₂ synthesis in rheumatoid arthritis synoviocytes by taurine chloramine