Simulation und Optimierung der Mehrstoff-Rektifikation

Simulation and optimization of multicomponent distillation . Different methods for simulating multicomponent distillation columns are presented and compared with respect to the effort required and the accuracy that may be obtained. Inclusion of mass transfer kinetics based on the laws of multicomponent diffusion in the models significantly increases computer time, but the additional accuracy in the prediction of concentration profiles may justify this effort also in design practice. In particular, the unusual behaviour of concentration profiles due to multidiffusion effects can only be explained by such improved models. The new methods of multicriteria optimization offer substantial advantages over a scalar-optimization and, in addition to economic criteria, also allow inclusion of aspects of operational safety and of environmental requirements.     

Anwendung von Rechenprogrammen bei der Simulation und Optimierung von Rektifizieranlagen in der fettchemischen Industrie

Application of Computer Programs on the Simulation and Optimization of Rectification Plants in Fatty Chemicals Industry Three calculation programs (Bubble point, Tomich, Newton Raphson) were used for the simulation of rectification plants and for the optimization of the plate to plate method. The application of these programs is explained with an example, each, from the practical problems: 1. Fractionation of fatty acids in a production column. The results of optimization calculations are compared with five different fatty acid fractions and the possibilities of increasing the capacity are shown. 2. Recovery of methanol from a mixture of KPK-methyl ester, glycerol and water. Three alternatives for the reduction of recovery costs are discussed with the aid of simulation programs. An essential part of the calculation is the determination of thermodynamic vapour-liquid equilibria. In this context, the material data program is briefly described together with the means for data collection.     

Auslegung und Optimierung von hybriden Trennverfahren

Design and Optimization of Hybrid Separation Processes Hybrid separation processes are defined as the combination of at least two different unit operations in different apparatus which contribute to the separation task. Hybrid processes are used for difficult separations, e.g., close‐boiling mixtures and azeotropes, if a single unit operation, e.g., distillation, membranes, extraction, crystallization or chromatography, is not efficient or even not feasible. Because of the structure of a hybrid process which implies two or more unit operations and recycle streams, the design is not straightforward and therefore subject of today's research. In this work general criteria for such a consistent design method are described and a design approach for hybrid separation processes is presented. It bases on rigorous modeling of the unit operations and simultaneous multivariable optimization. The approach feasibility is demonstrated by the separation of an isomer mixture.     

Automatisierung und Optimierung von Anfahr‐, Lastwechsel‐ und Batch‐Prozessen

Continuous processes show dynamics during load changes, start‐up and shutdowns whereas batch processes exhibit inherent dynamics. In the past, the major concern of automating these dynamics states of process operation were safe and reproducible operation, however, today modern methods of process operation allow for the economic optimization at the same time. The automation and optimization of batch processes pose challenges in several areas: Mastering the high complexity, connecting heterogeneous components by automation, and combining extensive knowledge from both process engineering and automation during project execution. This contribution describes approaches from industrial practice and punctually academic research, which solutions for the challenges are readily available and how to implement these.     

Anlagen zum Ultrahocherhitzen von Lebensitteln — Stand der Technik und Optimierung

Plant for ultra-high temperature processing of foodstuffs – State of the art and optimization . Continous ultra-high-temperature processes operating at temperatures between 135 and 160°C, for a few seconds, are high suitable for the preservation of liquid foodstuffs. Food sterilized in this way is packed under sterile conditions into sterilized containers which are then hermetically sealed. UHT-processes find application not only in the processing of milk, cream, puddings and desserts, to increase its storage lifetime, but also in the processing of soups and sauces. Currently, the third generation of UHT-equipment is appearing on the market. Depending on the method of heat supply, a distinction can be made between directly operated equipment having steam injection and indirectly operated equipment having heat exchangers. Highly viscous media are directly steam heated in wethed wall heaters. UHT-equipment must be regularly cleaned at 6 to 12 working hour intervals, to remove deposits formed on the heat exchanger surface at high temperatures. Thus, the length of time that the equipment is nonoperational, together with its degree of automation, its measuring, regulating and safety devices as well as maintenance and repair costs are of economic significance. Equipment optimization can be achieved under several headings. In the foodstuffs' industry, product quality is of prime importance and this is principally determined by the temperature/time ratio. For optimization of the thermal efficiency of the equipment, the sterilization parameters, F-and C-values, approved for use in preservation technology, can be used. By means of a study of reaction kinetics, it has been established that the F-and C-values can also be applied in the temperature range of UHT-processes.     

Struktursynthese und Optimierung nichtidealer Rektifizierprozesse

Optimization processes with MINLP are inherently capable of dramatically reducing the effort and time required for synthesis and analysis of separation processes. This approach represents an extremely powerful tool whose use, however, requires an understanding of process engineering. The principal advantage of the method lies in the simultaneous optimization of both the structure and also the operating conditions of a process. Reliable convergence to the global optimum requires careful limitation, scaling, and prior assignment of all variables. Starting values can be obtained by thermodynamic analysis of the phase equilibrium and by an overall balancing of the individual separation steps. Heuristic reduction of the superstructure generated on the basis of the preferred separation, appears appropriate given the present status of available models and solution algorithms. Under these conditions, the outer approximation algorithm recommended for this model will find the optimum solution after just a few iteration steps.