Modelling of Three Phase Sparged Reactors

This work presents the kinetic modelling and simulation of saponification of ethyl acetate in the presence of Sodium hydroxide in a plug flow reactor, Continues stirred tank reactor using Aspen Plus simulation Software. The continuous flow stirred-tank reactor (CSTR), also known as vat-or back mix reactor, is a common ideal reactor type in chemical engineering. A CSTR often refers to a model used to estimate the key unit operation variables when using a continuous agitated-tank reactor to reach a specified output. Plug flow reactors are widely used in the industry due to the non-mixing property. The use of plug flow reactors becomes significant when there is a need for continuous large scale reaction or fast reaction. Plug flow reactors have a high volumetric unit conversion as the occurrence for side reactions is minimum.

Solid-gas reactions are of great interest in many industrial fields such as nuclear, chemistry, metallurgy, CO2 capture, etc Industrial reactors where these reactions take place are difficult to understand. Indeed the solid phase is a granular medium through which circulate gaseous reactants and products. The properties of such a medium are modified in space and time due to reactions occurring at a microscopic scale. The thermodynamic conditions are driven not only by the operating conditions but also by the heat and mass transfers in the reactor. Several models have been developed to account for the complexity of these transformations such as the grain model [1] and the pore model [2] and all their improved derivatives. However most of these models are based on the law of additive reaction times of Sohn [3] for which the order respective to the gas in the kinetic rate equation must be equal to 1. However such condition is scarcely encountered in many gas-solid reactions so that err...

Catalysis Today, 2001

A comparative analysis is made for a trickle-bed reactor, a packed-bubble column, a three-phase fluidized bed and a slurry-bubble column with an active and moderately deactivating catalyst for the wet oxidation at high pressure and temperature of organic-containing aqueous wastes. Compared to other mature industrial sectors where multiphase reactors are prevalent, the design of three-phase catalytic reactors for wet air oxidation processes is still at an emerging stage. This paper discusses, from a multiphase reactor engineering perspective, the design of such contactors by setting an exhaustive modeling framework of catalytic wet oxidation in which the molecular, particle and reactor scales are integrated. The simulation results indicate that when wet oxidation is liquid-reactant limited, packed-bubble columns outperform trickle beds, whereas slurry-bubble columns are the most vulnerable to "coke" deactivation.

Clean Products and Processes, 2001

A comprehensive chemical reactor analysis tool was required to complete a project to develop an advanced on-line process optimization analysis system for pollution prevention. The advanced process analysis system integrates programs (reactors, on-line optimization, pinch analysis, and process¯ow-sheeting) to analyze and modify chemical processes for waste minimization. The reactor analysis program is to be used to evaluate and analyze multi-phase and catalytic reactors to suggest to the plant and process engineers the best reactor type and operating conditions. A multi-phase catalytic reactor design and analysis tool, ReaCat, has been developed. ReaCat incorporates models to design the following reactor types: plug¯ow, CSTR, batch, catalytic ®xed-bed, catalytic¯uidized-bed, gas±liquid stirred tank, trickle-bed, three-phase ®xed bubble-bed, bubble slurry column, CSTR slurry, and three-phase¯uidized-bed. This paper gives a summary of the multi-phase and catalytic reactors: classi®cations, theory and design models, numerical methods, and solution algorithms. A description of the reactor analysis tool including comparison cases with experimental data is presented.

Chemical Reaction Engineering: Essentials, Exercises and Examples presents the essentials of kinetics, reactor design and chemical reaction engineering for undergraduate students. Concise and didactic in its approach, it features over 70 resolved examples and many exercises. The work is organized in two parts: in the first part kinetics is presented focusing on the reaction rates, the influence of different variables and the determination of specific rate parameters for different reactions both homogeneous and heterogeneous. This section is complemented with the classical kinetic theory and in particular with many examples and exercises. The second part introduces students to the distinction between ideal and non-ideal reactors and presents the basic equations of batch and continuous ideal reactors, as well as specific isothermal and non-isothermal systems. The main emphasis however is on both qualitative and quantitative interpretation by comparing and combining reactors with and without diffusion and mass transfer effects, complemented with several examples and exercises. Finally, non-ideal and multiphase systems are presented, as well as specific topics of biomass thermal processes and heterogeneous reactor analyses. The work closes with a unique section on the application of theory in laboratory practice with kinetic and reactor experiments. This textbook will be of great value to undergraduate and graduate students in chemical engineering as well as to graduate students in and researchers of kinetics and catalysis.

Computers & Chemical Engineering, 1992

Generalized models for catalytic fixed bed reactors, trickle bed and slurry reactors and gas-liquid tank reactors were discussed. The numerical algorithms for solution of the reactor models were reviewed and discussed; the initial value problems appearing in the reactor models were solved by a stiff ODE-solver based on linear multistep methods, and the boundary value problems were solved by orthogonal collocation. The numerical algorithms proved to be suitable for solution of the reactor models under consideration. The generalized models were included as modules in a process simulator, and also standalone simulation packages were prepared. The use of the software was illustrated with the case studies: toluene hydrogenation, methanol synthesis, sulphur dioxide oxidation and chlorination of para-cresol.

Computer Aided Chemical Engineering, 2005

An integrated approach to the modelling of chemical reactors, particularly catalytic ones is presented. The modelling approach starts from quantum-chemical calculations, mechanistic hypothesis, derivation of kinetic expressions in order to achieve an appropriate kinetic model. The model parameters are determined by regression analysis and the complex behaviour of fixed bed reactors, including catalyst deactivation is described in an adequate manner. A general flowsheet for the procedure is proposed.