Stefan Brüggemann

Support of strategic business decisions at BASF's largest integrated production site based on site-wide Verbund simulation

Abstract The paper presents a novel large-scale sequential-modular simulation tool for expansion and refinement of Verbund sites with highly-interconnected networks of chemical production and infrastructure plants. The simulation uses a hierarchical model based on the sites cost centers, plants and unit operation modes which hold the stoichiometry and utility demand of each production step. A semi-automatical interface to the SAP database of the site is used for routinely updating the model with respect to the latest changes regarding structure and recipe parameters. Based on this model the impact of modifications in a single plant, for example a capacity increase, can be analyzed by giving a quantitative prediction of all relevant consequences across the linked value chains of the site. The new simulation tool is used to support strategic business decision making with respect to new investments, capacity adjustments and production planning. In addition, the gathered and consolidated data of the Verbund models are a valuable resource for strategic and operative business units.

Application of the rectification body method to batch rectification

This contribution focuses on the development of a dynamic conceptual model for a batch rectifier having an infinite number of stages without resorting to multistage calculations. For a given instantaneous still composition, the key feature of the method is the estimation of the instantaneous minimum reflux or the instantaneous distillate composition by using the Rectification Body Method. The usefulness of Bifurcation Analysis of pinch profiles is emphasized to model highly non-ideal behavior.

Design and optimization of recycle policies for multicomponent azeotropic distillation processes with bifurcation analysis

Abstract A novel design method for finding cost-optimized recycle policies for multicomponent azeotropic distillation processes is presented. The design task is formulated in form of a nonlinear optimization problem with the aim of minimizing the energy consumption of the process. The minimum energy demand of each column is determined using the rectification body method (RBM). Closure of the mass balance around each unit of the process is enforced by linear constraints. The feasibility of the split in each column with respect to the distillation boundaries is formulated as a nonlinear constraint. This measure of split feasibility is obtained from a bifurcation analysis of the pinch map which is based on reversible distillation theory. The ternary pressure-swing distillation of an ethanol-water mixture using acetone as an entrainer is used as an illustrative example for the optimization and the assessment of split feasibility.

Rapid screening of regular and thermally coupled design alternatives for nonideal multiproduct distillation processes

Abstract A shortcut design method for the separation of nonideal zeotropic and azeotropic mixtures in complex column sequences with and without energy integration is presented. It is based on the decomposition of the process into sequences of simple columns. The minimum energy demand of each column is determined using the rectification body method (RBM). Application of the design method allows rapid screening of the energy-efficiency of different process alternatives by ranking their overall energy demand, exergy consumption or utility cost. The method is illustrated with a nonideal zeotropic and an azeotropic separation example.