Development of a dynamic process model for the mechanical fluid separation in decanter centrifuges

The flowsheet simulation is a current simulation tool in the areas of research & development, plant design and production of chemical products. The objective of flowsheet simulations is the estimation of the overall process behaviour by solving mass and energy equations. The dynamic flowsheet simulation of particulate processes is a new tool which extends the classical simulation tools which are used in the chemical process engineering by the particle size distribution as one relevant new parameter. The complexity of particulate processes is given by the variety of material properties which depend on the particle size, particle size distribution, the volume fraction of solids and the physicochemical properties. This work illustrates a dynamic process model for continuous centrifuges and considers the material properties of the processed solids and the machine behaviour. First the theoretical framework is presented. Due to the complexity of the material, different material functions, such as the particle size distribution, hindered settling, consolidation or sediment transport used for the dynamic calculation of the process within a lab-decanter centrifuge. Example simulations show the capability of the presented approach. One main feature of the numerical approach is given by the fact, that the small numerical effort reveals the possibility for real time simulations which are applied in the process industry for calculation at the same rate as actual wall clock time

Supply Chain Risk Management in the Electronics Industry

The study on supply chain risk management has shown that the supply chain risk management is a particularly important and urgent issue in the industry. Especially in the electronics industry with its strong OEMs and weak suppliers the supply chain risk management should be a standardized method in a company and therefore needs to be taken into account. Companies increasingly recognize the importance of supply chain risk management, due to globalization and the associated increasing distribution of value-added activities, as well as the expansion and the growing complexity of the supply chains. The study also shows that supply chain risk management must analyze and be based upon both strategic and operational risks. Another interesting finding of the study is that the quality of supply chain risk management decreases with a shrinking vertical range of manufacture, and also that the process quality along the supply chain is reduced on the way to the end consumer. This is an important discovery for the electronics industry, since the distribution of value added and the vertical range of manufacture among the supply chain partners is low in the electronics industry. It has to be said that future research about the topic of supply chain risk management should focus on broadly based case studies conducted in the European Union and the other economic areas for significant, transnational equation. The developed process model has to be mitigated to other industries and branches. Therefore, future research will be concentrated on the development of methods for a process model that can be used and implemented in any industry and industrial sector. The described process model was developed to help SMEs in the electronics industry to evaluate the criticality of their supply chains. The methodology and the process model provide a systematic procedure that supports companies to minimize risks, enables companies to enhance their performance thanks to more stable supply chains, increases the productivity of companies by reducing the supply-related waiting times, and supports companies to increase their competitiveness based on a stabilized supply chain. Supply Chain risk management will be a key success factor for companies in a globalized world if they have implemented a risk management process in their organizational structure

La firma electrónica

Los cambios normativos que introdujo la Ley de Comercio Electrónico imponen modificaciones a figuras como la oferta misma, pues el uso de esta nueva herramienta debe producir tantos efectos como los manuscritos utilizados en el comercio. El rol determinante de la CNUDMI y el trabajo interno por comar vacíos normativos son objeto de estudio por los autores.

Soft sensor development for real-time process monitoring of multidimensional fractionation in tubular centrifuges

High centrifugal acceleration and throughput rates of tubular centrifuges enable the solid–liquid size separation and fractionation of nanoparticles on a bench scale. Nowadays, advantageous product properties are defined by precise specifications regarding particle size and material composition. Hence, there is a demand for innovative and efficient downstream processing of complex particle suspensions. With this type of centrifuge working in a semi-continuous mode, an online observation of the separation quality is needed for optimization purposes. To analyze the composition of fines downstream of the centrifuge, a UV/vis soft sensor is developed to monitor the sorting of polymer and metal oxide nanoparticles by their size and density. By spectroscopic multi-component analysis, a measured UV/vis signal is translated into a model based prediction of the relative solids volume fraction of the fines. High signal stability and an adaptive but mandatory calibration routine enable the presented setup to accurately predict the product’s composition at variable operating conditions. It is outlined how this software-based UV/vis sensor can be utilized effectively for challenging real-time process analytics in multi-component suspension processing. The setup provides insight into the underlying process dynamics and assists in optimizing the outcome of separation tasks on the nanoscale

Development of Prediction Models for Pressure Loss and Classification Efficiency in Classifiers

This paper presents the development of prediction models for pressure loss and classification efficiency in classifiers. Classifiers belong to one of the most important classification devices in gas particle processing and a fast and accurate determination of pressure loss and cut size is of great interest. The first model developed in this work allows the calculation of pressure loss as a function of geometric and operational parameters. It is based on a number of measured values that are obtained from previous numerical simulations (CFD). The maximum deviation of the model is less than 20% and the model operates in real time. However, the model requires calibration for each type of classifier. The second model for classification efficiency is based on a simplified two-dimensional approach in which the flow profile and particle trajectories are determined exclusively for the area between two classifier blades. The model is applicable for all geometrical and operational parameters and calculates the desired parameters within a few minutes, with a maximum error rate of 25%. In combination, the two models allow for the process optimization of classifiers in complete systems

Effects of flow baffles on flow profile, pressure drop and classification performance in classifiers

This paper presents a study of the use of flow baffles inside a centrifugal air classifier. An air classifier belongs to the most widely used classification devices in mills in the mineral industry, which is why there is a great interest in optimizing the process flow and pressure loss. Using Computational Fluid Dynamics (CFD), the flow profile in a classifier without and with flow baffles is systematically compared. In the simulations, turbulence effects are modeled with the realizable k–ε model, and the Multiple Reference Frame approach (MRF) is used to represent the rotation of the classifier wheel. The discrete phase model is used to predict the collection efficiency. The effects on the pressure loss and the classification efficiency of the classifier are considered for two operating conditions. In addition, a comparison with experimental data is performed. Firstly, the simulations and experiments show good agreement. Furthermore, the investigations show that the use of flow baffles is suitable for optimizing the flow behavior in the classifier, especially in reducing the pressure loss and therefore energy costs. Moreover, the flow baffles have an impact on the classification performance. The impact depends on the operation conditions, especially the classifier speed. At low classifier speeds, the classifier without flow baffles separates more efficiently; as the speed increases, the classification performance of the classifier with flow baffles improves