Reversible, noncatalytic reactions between gases and solids in fixed beds

Mutasher, E. I.; Khan, A. R.; Bowen, J.H.

doi:10.1021/ie00094a020

Cited by 7 publications

(8 citation statements)

References 2 publications

(2 reference statements)

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“…Mutasher et al [14] and Khan and Bowen [1] have developed a mathematical model for gas-solid noncatalytic reaction in a spherical geometry based on the diffuse interface concept. Different types of concentration profiles within the reaction zone -linear, sigmoidal and exponential -have been proposed, the sigmoidal case being shown in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

“…Mutasher et al [14] have shown the effect of reversibility on breakthrough curves for an isothermal fixed bed reactor based on single pellet behavior in Figure 5. The effect of equilibrium constant K on the concentration profile and zones development has been seen in Figure 6.…”

Section: Resultsmentioning

confidence: 99%

“…For the equilibrium concentration of m ϩ n ϭ 1, gaseous reactant, [A*] can be written as given by Mutasher et al [14]:…”

Section: Model Developmentmentioning

confidence: 99%

“…This work illustrates how these values of resistance contribute to the overall reaction with the lapse of time. The general modified form of the diffuse interface model for reversible gas-solid noncatalytic reaction in conjunction with the experimental data of Ansari and Bowen [3] is used to rectify some of the assumptions introduced by Mutasher et al [14] (…”

Section: Zone II Z 2 (Linear Profile)mentioning

confidence: 99%

“…Szekely and Evans, [5,6] Evans and Song, [11] Ranade and Harrison, [12] and Evans and Rande [13] have considered reversibility in gas-solid reactions using a grain model, where one mole of gaseous reactant produces one mole of gaseous product. Mutasher et al [14] have applied a diffuse interface model for fixed bed reactor for an isothermal reversible gas-solid reaction. Their assumption of linear concentration profile within the reaction zone has restricted its application.…”

Section: Introductionmentioning

confidence: 99%

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Non-catalytic, gas-solid reversible reaction mechanism implementing diffuse interface model

Khan

1999

Int. J. Chem. Kinet.

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Gas-solid reactions in chemical and metallurgical industries often involve solid pellets and a gaseous reactant. The progress of chemical reaction is measured by the movement of zones within the pellet and has been explained in terms of diffusion and chemical reaction processes. Earlier models identified a single reaction zone, in addition to product layer and unreacted core. In the present article, two reaction zones are envisaged as a more plausible explanation of the movement of the zones as the reaction proceeds. Earlier models for reversible reactions have assumed that conditions at the interface between the reaction zone and the unreacted core correspond to equilibrium at the prevailing temperature. The gaseous concentrations were assumed to permeate the core at the interfacial values so that no reaction occured in the core. More realistically, the present article envisages an additional zone within which the gaseous concentrations fall from the equilibrium values to zero. It is assumed that in the reaction zone proper, referred to as zone I, having thickness z I , the concentration profile is sigmoidal. This agrees with the earlier work of Khan and Bowen [1] and Prasannan and Doraswamy.[2] In zone I and the concentration of the reactant gas varies between [A i ] and [A*]. In the zone II, having thickness z 2 , concentration varies linearly between [A*] and zero. This model has been applied successfully to the data of the reduction of hematite [3] at different temperatures. The contribution of different forms of resistance, diffusion in product layer, chemical reaction and diffusion in the reactant core, is assessed as function of time (start to the end of reaction). The thickness of the zones remain almost constant as the reaction progresses. In particular, the influences of the product and core diffusion coefficients and chemical equilibrium constant on the extant reaction are evaluated. The dependence of concentration profile and zone thickness on equilibrium constant, K, velocity constant, k, diffusional coefficients D C and D P has been investigated thoroughly. The thickness of both zones has been evaluated for leading variables.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…For the equilibrium concentration of m ϩ n ϭ 1, gaseous reactant, [A*] can be written as given by Mutasher et al [14]:…”

Section: Model Developmentmentioning

confidence: 99%

Section: Zone II Z 2 (Linear Profile)mentioning

confidence: 99%