AEROGELS 2018 – Supercritical drying of aerogels – Thermodynamic considerations for critical process steps
The session on Supercritical Drying on 26 September 2018 at the Fourth International Seminar on Aerogels will start with André Mohs and Volker Steinhagen from Uhde High Pressure Technologies, one of the sponsors of the conferencs. As experts in High Pressure Technologies they will present an overview on some critical process steps of the aerogel drying.
The aerogel drying process can be considered the most critical step when it comes to the generation of aerogels. Although there are different approaches for this process step, the most common process in larger scale is the drying of the aerogel by exchanging the solvent inside of the material (in most cases an organic solvent like ethanol, acetone, etc.) with supercritical CO2and expanding it to the gaseous phase in an additional process step without passing the two-phase region.
The equipment for this process resembles in many ways the equipment which is used for extraction processes of natural raw materials with supercritical CO2. The benefit in using this type of equipment is that it has already been used for a variety of products with different capacities within the past 4 decades so the design and reliability of such equipment is well established. However, due to the large amount of organic solvent in the process, there are some major differences to be kept in mind when it comes to process development for the drying process of aerogels. The largest difference lies in the properties of the solvent mixture, which vary strongly with composition and process conditions and thus cannot be considered to be equal to pure CO2or to pure solvent properties.
This presentation gives an overview on some critical process steps of the aerogel drying, where the knowledge of thermodynamic behavior is essential for process development. Furthermore, thermodynamic based side-effects during the operation of such a drying plant will be presented. A short overview on cost drivers with regard to process changes due to thermodynamic behavior of the CO2-solvent mixture are discussed as well.
Uhde High Pressure Technologies is one of the sponsors of the 4th International Seminar on Aerogels. Uhde High Pressure Technologies is a high technology company of thyssenkrupp with approx. 300 employees. It is one of the world’s leading companies for industrial high pressure plants and equipment. Their services comprise the entire plant life cycle from the planning phase with in-house engineering to the operation phase with service and spare parts supply. As they are specialists on high pressure technologies including supercritical drying plants for aerogel drying processes comprising systems from lab-to large production scale belong to their product and service portfolio.