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27 Apr 2017

Low temperature reactors

Low Temperature Reactors / Operationally Safe and Reliable Mechanical Seals

Certain processes are increasingly operated at low temperatures down to –100°C in order to achieve high selectivity in reactions or separation processes, for example in polymerizations reactors for rubber production or crystallizers for the separation of isomer mixtures. In such cases low temperature mechanical seals are used for sealing the agitator shaft. Their structural design, materials, elastomeres, lubricants and supply units have been specifically designed for these extreme conditions so that high operational safety can still be achieved and costly shutdowns are avoided during procedures that primarily consists of continuous operation.

For the development and optimization of these seals, EKATO first of all determines the temperature profile within the individual components by means of finite element analysis (FEA) that is based on the given operating and environmental conditions. After an experimental validation of the numerical model, reliable parameter studies can be carried out for the different operating and boundary conditions.

Special attention is paid not only to the seal rings and their materials and behavior in the hydrodynamic sealing gap. To maintain the sealing function, buffer fluids must also be chosen that satisfy the required properties with respect to lubrication and heat transfer at low temperatures and at the same that are compatible with process media. Even the elastomers for static sealing must retain their mobility which is taken into consideration during the stages of material selection and constructive design of the sealing area.

Once the design has been successfully optimized, then a verification process is carried out which examines the results with respect to temperatures and pressures by means of test runs at the mechanical seal testing stand and under real operating conditions. The focus is on the temperature development of the seal surfaces, the temperature distribution within the entire mechanical seal and any potential leakage.

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