Modeling of Reactive Absorption Using the Maxwell−Stefan Equations

Abstract

The modeling and design of reactive absorption is based on a theoretical description of reaction and mass transport in multicomponent systems. The multicomponent nature of these phenomena leads to complex process behavior due to the superposition of many driving forcessmulticomponent diffusion, chemical interactions, convective flows, multicomponent thermodynamic interplay, etc. For this reason, an adequate theoretical description of the multicomponent reactive systems calls for the application of the Maxwell-Stefan equations and, further, for the use of matrix coupled mass-transfer equations together with the relevant reaction kinetics. On this basis, a two-phase, gas-liquid system is considered and a general model is developed for its design. Reactions in both liquid and gas phases are taken into account, and both the film and bulk reaction mechanisms are allowed for. The transport equation describing the film phenomena is solved analytically by using a linearization of the reaction term. The model is applied to the description of NO x absorption. A comparison of the experimental and theoretical results demonstrated their good agreement.

Rigorous Modeling of Reactive Absorption Processes

“…With some further assumptions concerning the diffusion and reaction terms, this allows an analytical solution of the boundary value problem (Eqs. (10), (11)) in a closed matrix form (see [24,26]). On the other hand, the boundary values need to be determined from the total system of equations describing the process.…”

“…(3), (4). The interfacial liquid-phase concentrations are related to the relevant gas-phase concentrations y I i by the thermodynamic equilibrium relationships and by the continuity condition for the molar fluxes at the interface [14,26].…”

“…Generally, all these considerations are also valid for the gas film phase provided that reactions occur there [26]. Both the analytical and numerical solution of the coupled diffusionreaction film problem is analyzed at full length in [27], their particular applications are considered in the following sections 4.1 and 4.2.…”

“…(19) gives simple analytical expressions for the component fluxes with regard to the homogeneous reaction in the fluid films (see [26] …”

Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

“…Onda et al (1970) developed an approximated solution for the general case using the linearization method proposed by Hikita and Asai (1964) to simplify the reaction rate [19,20]. Another approach, developed by Kenig and his coworkers, is to solve directly a multicomponent two-zone advection-diffusion-reaction model using a Maxwell-Stefan formulation of the problem [21][22][23][24][25].…”