Gas-liquid mass transfer in a slurry reactor operating under olefinic polymerization process conditions

Li, J.; Tekie, Zeru; Mizan, Tahmid I.; Morsi, Badie I.; Maier, E.; Singh, Chandra Prakash

doi:10.1016/0009-2509(95)00272-3

Cited by 28 publications

(36 citation statements)

References 28 publications

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“…In fact, in the case of H,, N, and CO, kLa values appeared to increase with pressure, while for CH4 and C,H4, k, a values were not affected or showed a slight decrease with pressure. Li et al (1996b) found a similar behavior for H, and C,H, in n-hexane containing polypropylene powder. Miller and Ekstrom (1990), on the other hand, reported in n-octacosane that kLa values for CO increased with pressure, whereas those for H, were independent of it.…”

Section: Effect Of Pressure and Temperature On Klasupporting

confidence: 68%

“…At low catalyst concentrations (about 12.5 mass%), H,, CO and CH, showed a slight increase of kLa values with solid concentration. Kars et al (1979), Li et al (1996b), Vinke et al (1993) and Bruck and Hammer (1986) reported that small amount of solids could increase kLa values. Beenakers and van Swaaij (1993) pointed out that this increase occurs at low solid concentrations and by different mechanisms, such as the "grazing effect", which they defined as the intermittent movement of small particles between the gadliquid film and liquid bulk.…”

Section: Efect Of Pressure and Solid Concentration On Klamentioning

confidence: 94%

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Effect of catalyst loading on gasliquid mass transfer in a slurry reactor: A statistical experimental approach

Inga

Morsi

1997

Can J Chem Eng

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A statistical experimental design was employed to study the effects of pressure, temperature, catalyst loading, and mixing speed on the solubilities (P) and volumetric gadliquid mass transfer coefficients (kLa) for H,, N,, CO, CH, and C,H, in a liquid mixture of hexanes containing iron oxide catalyst in a 4-litre agitated autoclave. Statistical correlations for k,a values for the gases used were developed. Mixing speed and solid concentration showed the strongest effects on k,a. At low catalyst concentrations, a maximum in kLa was observed and at concentrations > 37 mass%, kLa decreased by more than one order of magnitude.On a utilise un plan d'experience statistique afin d'etudier les effets de la pression, de la temperature, du chargement de catalyseur et de la vitesse de melange sur 1es solubilites (CC) et les coefficients de transfert de matiere volumetriques gadliquide (k,a) pour H,, N,, CO, CH, et C,H, dans un melange liquide d'hexanes contenant un catalyseur a I'oxyde de fer dans un reservoir agite de 4 litres. Des correlations statistiques ont ete etablies pour les valeurs de k,a pour les gaz utilises. C'est la vitesse de melange et la concentration de solides qui agissent le plus sur kLa. A de faibles concentrations de catalyseur, on a observe un maximum dans k,a et a des concentrations > 37% massique, kLa diminue de plus d'un ordre de grandeur.

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Section: Effect Of Pressure and Temperature On Klasupporting

confidence: 68%

Section: Efect Of Pressure and Solid Concentration On Klamentioning

confidence: 94%

Effect of catalyst loading on gasliquid mass transfer in a slurry reactor: A statistical experimental approach

Inga

Morsi

1997

Can J Chem Eng

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“…On one hand, it is an essential component which activates the potential active sites; however, it also acts as deactivating agent [13,15,16]. The optimum precontacting time depends on the active sites formation [22] (i.e., titanium reduction from Ti +4 to Ti +3 and Ti +2 ) and on cocatalyst external and internal mass transfer limitations [5]. Catalyst activity is strongly influenced by titanium oxidation state; particularly the decrease of activity for longer than the optimal precontacting time can be attributed to an overreduction of the titanium [13,16].…”

Section: Resultsmentioning

confidence: 99%

“…That is, the rate of cocatalyst molecules transfer from the liquid phase to the solid catalyst particles becomes the limiting step. In the past 30 years, various correlations have been proposed in the open literature for the calculation of liquid-solid components mass transfer coefficients for spherical particles in a flowing liquid medium [19][20][21][22][23][24]. However, depending on the selected mass transfer correlations, the estimated values of liquid/solid film mass transfer coefficients for small size particles (i.e., <50 m) and low Reynolds numbers can vary from the real values by several orders of magnitude [25].…”

Section: +mentioning

confidence: 99%

Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

Aigner

Paulik

Krallis

et al. 2016

Journal of Polymers

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In industrial-scale catalytic olefin copolymerization processes, catalyst and cocatalyst precontacting before being introduced in the polymerization reactor is of profound significance in terms of catalyst kinetics and morphology control. The precontacting process takes place under either well-mixing (e.g., static mixers) or plug-flow (e.g., pipes) conditions. The scope of this work is to study the influence of mixing on catalyst/cocatalyst precontacting for a heterogeneous Ziegler-Natta catalyst system under different polymerization conditions. Slurry ethylene homopolymerization and ethylene copolymerization experiments with 1-butene are performed in a 0.5 L reactor. In addition, the effect of several key parameters (e.g., precontacting time, and ethylene/hydrogen concentration) on catalyst activity is analyzed. Moreover, a comprehensive mass transfer model is employed to provide insight on the mass transfer process and support the experimental findings. The model is capable of assessing the external and internal mass transfer limitations during catalyst/cocatalyst precontacting process. It is shown that catalyst/cocatalyst precontacting is very important for the catalyst activation as well as for the overall catalyst kinetic behavior. The study reveals that there is an optimum precontacting time before and after which the catalyst activity decreases, while this optimum time depends on the precontacting mixing conditions.

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“…Henry constants for ethylene and hydrogen in n-hexane (given in m 3 kgf/cm 2 /kg) are provided by Li et al (1996).…”

Section: Parameters and Constitutive Equationsmentioning

confidence: 99%

Oscillatory behaviour of an industrial slurry polyethylene reactor

et al. 2010

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Considerable attention has been given to the dynamic behaviour of polymerisation processes. Distinct non-linear phenomena have been predicted (multiple steady states, periodic, and non-periodic oscillations), but experimental confirmation of such responses has been usually confined to free-radical polymerisations systems. Particularly, olefin polymerisation reactors are expected to exhibit complex oscillatory dynamics, but this sort of dynamic behaviour has not been reported experimentally. In this work, real industrial data obtained in a full-scale polyethylene slurry reactor confirm the existence of complex oscillatory behaviour that can lead to process runaway, validating model predictions about the existence of complex dynamics in similar processes.On a porté une attention toute particulière au comportement dynamique des procédés de polymérisation. Des phénomènes distincts non linéaires ontété prédits (régimes permanents multiples, oscillations périodiques et non périodiques), mais la confirmation expérimentale de ces réactionś etait habituellement réservée aux systèmes de polymérisation radicalaire. Les réacteurs de polymérisation des oléfines sont censés avoir des dynamiques oscillatoires complexes, mais ce type de comportement dynamique n'a pasété démontré sur le plan expérimental. Dans la présenté etude, de véritables données industrielles relevées sur un réacteurà combustible en suspension en polyéthylèneà grandeéchelle ont confirmé l'existence d'un comportement oscillatoire complexe qui peut provoquer un emballement du processus. Ces résultats valident les prédictions du modèle relativesà l'existence de dynamiques complexes dans des processus similaires.

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Gas-liquid mass transfer in a slurry reactor operating under olefinic polymerization process conditions

Cited by 28 publications

References 28 publications

Effect of catalyst loading on gasliquid mass transfer in a slurry reactor: A statistical experimental approach

Effect of catalyst loading on gasliquid mass transfer in a slurry reactor: A statistical experimental approach

Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

Oscillatory behaviour of an industrial slurry polyethylene reactor

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