Frederick J. Krambeck

6 Development of mobil's kinetic reforming model

Abstract Mobil Research and Development has developed a kinetic process model for catalytic naphtha reforming which is currently used extensively throughout Mobil for commercial reformer monitoring, research guidance, new process designs, planning, and optimization. The experimental and mathematical development of Mobils kinetic reforming model is presented in this paper.

Kinptr (Mobil's Kinetic Reforming Model): A Review Of Mobil's Industrial Process Modeling Philosophy

Publisher Summary This chapter discusses kinetic platinum reforming (KINPTR) model that was completed in 1974. Because the model was developed from a fundamental basis, it has been invaluable to Mobils research efforts in evaluating novel process designs, investigating catalyst improvements, and diagnosing commercial reformer problems. The model includes fundamental hydrocarbon conversion kinetics developed on fresh catalysts, referred to as start-of-cycle kinetics, and the fundamental relationships that modify the fresh-catalyst kinetics to account for the complex effects of catalyst aging (deactivation kinetics). The successful development of this model was accomplished by reducing the problem complexity. A thorough understanding of the chemistry, thermodynamics, and catalyst deactivation is always necessary to reduce the problem to a manageable size without loss in accuracy. Since its development, KINPTR has had a major impact in Mobils worldwide operations. It can be accessed by personnel at each of Mobils locations throughout the world. The detailed kinetics for the C 6 hydrocarbons is provided in the chapter that focuses on the overall program structure of KINPTR, its start-of cycle and deactivation kinetics, the models accuracy, examples of KINPTR use within Mobil, and the rationale for the kinetic lumping schemes.

A reactor design simulation with reversible and irreversible catalyst deactivation

Abstract In Mobils Methanol-to-Gasoline (MTG) Process, two types of catalyst deactivation occur. The first type is reversible coking of the zeolite; the coke is burned off during regeneration, restoring activity. The second type is permanent deactivation of the zeolite. We have developed a dynamic simulation of the MTG process to investigate the interaction between these two types of deactivations. In our simulation, the rate of the coking depends on the amount of irreversible deactivation that had previously occurred. Also, the permanent deactivation occurs both during the reaction and catalyst regeneration. With this type of deactivation interaction, we were able to predict experimental observations in our pilot plant studies; in particular, the second cycle on a given catalyst is longer than the first cycle. We have used the model to compare the overall catalyst cycle life for both adiabatic and isothermal reactor simulations.

Heater probe technique to measure flow maldistribution in large scale trickle bed reactors

Abstract Novel flow distribution measurement probes were used in a large-scale commercially operating trickle-bed reactor. The probes consist of long heated pipes designed to measure local heat transfer coefficients at multiple points along their length. Local flow rates are correlated with the heat transfer coefficient based on independent laboratory data. The results of our study showed significant point-to-point variation in flow distribution. The pattern of maldistribution would vary with alternate operating conditions of flow rates, temperature, and liquid volatility. Results included an increase in the nonuniformity of flow moving down the reactor in the direction of flow. And severe maldistribution with poor reactor performance occurred at high liquid mass flux.

Thermodynamics and kinetics of complex mixtures

Abstract Analysis of the chemistry and kinetics of mixtures with very large numbers of chemical compounds, such as petroleum fractions and their reaction products, can be simplified by assuming an infinite number of compounds with properties that are continuous functions of one or more variables. The limiting forms of stoichiometric, thermodynamic and kinetic concepts as the number of compounds tends to infinity is of interest for these systems. Previous treatments of this subject, such as those by De Donder (1931) and Aris and Gavalas (1966) , did not exploit an important property of these systems; that the subspace of stoichiometric constraints is of finite, and in fact small, dimension even when the reaction subspace is infinite. This profoundly simplifies the geometry of the equilibrium surface in composition space. Another very useful property of kinetic functions is the detailed balance principle. Here, this is expressed in a very general form, reminiscent of the Onsager principle. The concepts are illustrated by means of concrete examples.

Development of trickle-bed heat transfer correlation for flow measurement probe

Abstract The heat transfer coefficient from a heated pipe in a trickle-bed catalytic reactor was correlated with combined gas and liquid flow rates along with fluid and packing physical properties. The correlation is readily applicable for flow rate measurements in commercial-scale trickle-bed reactors. Data for the correlation were obtained using petroleum distillate liquid fed to a laboratory reactor over a range of temperatures along with hydrogen and nitrogen as gases. Our analysis showed that the heat transfer coefficient data are represented based on the combined thermal mass flux of the fluids plus the effective conductivity of the packed bed. The latter depends on gas, liquid, and solid thermal conductivities, but not significantly on flow rates or flow regime.