(491f) Multi-Scale Analysis of Chemical Reactors Using Green's Function Method

The availability of mathematical description of process models helps in the design, operation and optimization of reactors. The accurate representation of various phenomena at appropriate scale helps in the overall performance improvement of the chemical process plants. The modern-day reactor therefore needs to be investigated at various length and time scales. However, the multi-scale and multi-phase phenomena occurring in a general reactor are very difficult to represent in a single system of conservation equations. The unavailability of constituent equations also poses challenges in such multi-scale representation.

This work explores a possible integration of the catalyst scale to reactor scale phenomena using the Green’s function approach; the capability of object-oriented software design is exploited in our work towards putting up a generic modelling and simulation framework based on mass, momentum and energy conservation equations. The manipulation of the general conservation equations based on specific user inputs on the reactor properties is used to arrive at the specific final form of the conservation equations for the chosen reactor type.

In our work we propose an integration of the various phenomena occurring at the reactor scale as well as the catalyst particle scale. The temperature and concentration profiles inside the catalyst particles and inside the reactor yields partial differential equations. Such formulated partial differential equations are conventionally solved using FDM, FEM or FVM. In this paper we adopt a more generalizing approach for solving these equations using Green’s Function Method.

This paper shows the commonality that exists in the various terms like diffusion, convection and accumulation for catalyst length scale and reactor length scale. Using the example of cylindrical shaped catalyst particles in a two-phase catalytic cylindrical fixed bed reactor, it has been shown that the same Green’s function approach is applicable at both particle scale and reactor scale.