New approach to refinery process simulation with adaptive composition representation

Abstract:
The established technique for the simulation of refinery processes is the use of pseudocomponents. However, in order to increase the economical benefit of plant operation, it seems inevitable to include molecular information in petroleum mixtures characterization. This will lead to a strong increase of problem size. For this new class of models currently there seems to be no special algorithms available. This paper compares the classical pseudocomponent approach with a newly developed solution strategy, which is explicitly developed to efficiently solve simulation problems with a high detail in composition representation. The new solution strategy is an adaptive multigrid method on the basis of a Wavelet-Galerkin discretization. With the Wavelet-Galerkin discretization the model can easily be formulated on various levels of compositional detail. In an iterative procedure the multigrid concept exploits this different formulations to construct correction term approximations to the true solution. The discretization of these correction term models is now done with a compositional detail which is determined by a residual based adaptation strategy. The proposed method has been implemented for a simple 9-stage distillation column and tested for a variety of feed mixtures. In all investigated tests the proposed method has shown to be superior to the conventional pseudocomponent approach in terms of accuracy and efficiency.

Keywords:
Complex multicomponent mixtures, multigrid, model reduction, adaptivity, pseudocomponents, petroleum, simulation.

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