Scale‐up und detaillierte Prozessanalyse eines Membranreaktors am Beispiel einer heterogen katalysierten Veresterung

The combination between reaction and pervaporation has been investigated using the example of a heterogeneous catalysed esterification reaction. The process model parameters have been determined based on experimental investigations and a scale‐up has been performed to the pilot scale. A detailed process analysis leads to optimal operating as well as structural variables and two separation sequences have been suggested.     

Statistische Prozeßführung (SPC) und Automatisierung (APC)

Statistical Process Control (SPC) and Automatic Process Control (APC). Statistial Process Control as developed by Shewhart and Deming is being used internationally as a method for continuous improvement and cost reduction. SPC is applied to manufacturing and service industries, and is now being used more and more in Germany. In the chemical industry many processes are equipped with automatic control or advanced control strategies. This article outlines how SPC and APC supplement each other. The first part describes APC methods as a means of achieving constant quality. The second part describes SPC in its original form as a method for continuous quality improvement. After the comparison of SPC and APC an example is presented: automatic rectifying column. The combined application of SPC and APC leds to synergistic results which would have been hard to achieve otherwise.     

Instationäre Prozeßführung kontinuierlicher Reaktoren

Non-steady-state operation of continuous reactors . The behaviour of continuous chemical reactors can be altered significantly by forced oscillation of the reactor parameters such as feed concentration of the reactants, flow rate, and temperature. In contrast to autonomous oscillations in unstable systems, the forced periodic disturbances are controlled and can be used as a further parameter for process optimization. The dynamic behaviour of individual steps of the overall reaction and of the reactor can be exploited to obtain performances and selectivities which cannot be accomplished in the traditional way on steady-state operation under comparable conditions. This is shown in discussing some simple kinetic schemes published in theoretical studies and comparing them with experimental results for homogeneous and heterogeneous reactions. The physical and chemical causes for the predicted and observed advantages of periodic operation are discussed.     

Prozeßvergleich von Umkehrosmose und Elektrodialyse am Beispiel der Nitrat-Entfernung aus Grundwässern

Comparison of reverse osmosis and electrodialysis for removal of nitrate from groundwater . Reverse osmosis and electrodialysis are membrane processes suitable for desalination of aqueous solutions. Both processes were tested on a pilot scale in a waterworks for removal of nitrate from groundwater. A combination of the processes was also considered with a view to very high concentration of the residual water. The article shows how information gathered from long-term reverse osmosis trials and the experiments with the electrodialysis plant with industrial membrane dimensions can provide a basis for safe design of large plants. Treatment costs for large capacities are shown for the example of the above feed water. The advantages and disadvantages of reverse osmosis and electrodialysis are compared. This comparison demonstrates fitting applications of the two processes in other areas (chemical industry, sewage treatment).