Victor Alejandro Merchan

Hierarchical Simulation of integrated Chemical Processes with a Web based Modeling Tool

A novel approach for the systematic and hierarchical derivation of process models is presented. Model candidates for different unit phenomena are collected and rated on the basis of the model structure, origin and the modelers belief. The process model is created as a superstructure with the competing partial models. Thereby, it is possible to determine the best possible combination through optimization with respect to different objective functions. The systematic procedure has been implemented into the online web modeling platform MOSAIC. Based on the superstructure, optimization code for the state-of-the art optimization and simulation software can automatically be created. Based on two case studies, the new approach is demonstrated, namely a process model for the hydroformylation of long-chain olefins and a model for the pressure drop in packed columns with foaming components.

A Novel Process Design for the Hydroformylation of Higher Alkenes.

Abstract The hydroformylation is one of the most important industrial applications of homogenous catalysis. Due to the decreasing solubility of alkenes with an increasing length of carbon chains in the aqueous phase, the hydroformylation of higher alkenes is not carried out in a biphasic homogeneous system but in a single homogeneous organic phase with the use of a less reactive cobalt catalyst. However, this requires expensive reaction conditions such as high pressures and temperatures. Alternatively, the hydroformylation of higher alkenes with rhodium catalysts has been investigated in a batch operation mode by several scientists ( Haumann et al., 2002, Miyagawa et al., 2005 ). Moreover, their research proved that this process can be carried out in a homogenous environment by the use of micellar systems (e.g. microemulsions). Due to the high cost of catalysts containing phosphine ligands and rare metals, their retention in continuous processes is extremely valuable. In this work, we propose a novel process design for a continuous operation for the hydroformylation of higher alkenes. This process design is defined by a combination of the rhodium-catalysed hydroformylation of higher alkenes in micellar systems including the catalyst recycle. Due to the high costs of rhodium, the catalyst has to be separated completely from the reaction products so as to ensure high process profitability. The recycle is accomplished in two steps, which comprise a decanter and an ultrafiltration step. Moreover, in order to show the feasibility of the proposed process concept, simulation studies, and sensitivity analysis are carried out within a broad operating range. The corresponding modeling work has been executed using the web-based modeling environment MOSAIC ( Kuntsche et al., 2010 ).

Modeling, Simulation, and Economic Evaluation of a Hybrid CO2 Capture Process for Oxidative Coupling of Methane

Abstract The Oxidative Coupling of Methane (OCM) is a direct path for the conversion of methane into ethene. Carbon dioxide is generated as an undesired reaction by-product and must be removed in the downstream separation section. This is commonly achieved by amine scrubbing, which is an energy-intensive process. An alternative hybrid process employing gas separation membranes and absorption is investigated in this contribution. Membrane and absorption processes are modeled and simulated. Several flowsheet configurations and gas compositions, reflecting different OCM reactor concepts, are considered. Preliminary economic analysis is carried out to assess the feasibility of applying this process industrially.

Generation of first and higher order derivative information out of the documentation level

Abstract The accurate and efficient evaluation of first and higher order derivative information of mathematical process models plays a major role in the field of Process Systems Engineering. Although it is well known that the chosen methods for derivative evaluation may have a major impact on solution efficiency, a detailed assessment of these methods is rarely made by the modeler. Since standard modeling tools and some solvers normally only support own default methods for derivative evaluation, the evaluation of further methods can be a tedious work, and thus requiring the connection of different tools. In this contribution the implementation of a general method for generation of derivative information out of the documentation level is presented. Exploiting the possibility of code generation given by the web-based modeling environment MOSAIC ( Kuntsche et al. 2011 ), derivative information of model equations is generated either by symbolic derivatives or by coupling the models with state of the art automatic differentiation (AD) tools. This offers the modeler different methods of getting exact derivative values and opens the possibility of integrating the assessment of derivative evaluations within the modeling and simulation workflow.