The ARDC consists of an axis with rotating discs that ensure mixing of feed and solvent and flow- calmed settling zones in which raffinate and extract can separate. The separate settling zone of the ARDC has significant advantages even against symmetrically designed conventional rotary extractors. The separation is significantly more controlled and thus more effective, as unwanted flow entrainment is avoided.

Approximately 6 mixer/settler stages are realised in one ARDC. The name comes from the off-centre axis of rotation of the mixing zone.
For the removal of aromatics from the DAE, furfural or NMP are used as solvents. While the NMP tolerates higher process temperatures, the possible process temperature for furfural is limited due to the higher partial pressure. However, furfural has a higher selectivity towards mono-aromatics than NMP and can therefore be used in a lower solvent to feed ratio. The process-relevant data are determined in advance by piloting in pilot plants of Technoforce Solutions. Figure 4 shows the settling zones in a glass column, which is used to adjust the flow conditions. Figure 5 shows one of the piloting plants.

Even at lower temperatures, the removal of aromatics to values far below those required by EU Directive 2005/69/EC can be achieved by getting a good TDA yield.

Technoforce has already designed and built more than 60 Asymmetric Rotating Disk Column Units for Petrochemical industry, Fine chemistry, Pharma and other industrial sectors. Within the scope are also other extraction technologies as well as other technologies like Short Path Distillation, Agitated Thin Film Evaporation and Drying, Falling Film, Rising Film and Forced Circulation Evaporation, as well as Liquid-Liquid Extraction and Crystallization.

The Technoforce Plug Flow Crystallizer consists of a horizontal cylinder fitted with one or more separate double jackets. This allows the crystallizer to be individually tempered in different sections to create a graduated temperature profile. In cooling crystallization, for example, an 80°C solution could be cooled to 60°C, then to 40°C and further to 20°C to control crystallization. A specially designed rotor ensures good mixing within a section, however from section to section (i.e., from temperature level to subsequent temperature level) the system forces a plug flow without significant back-mixing. The rotor design also minimizes mechanical energy transfer into the crystal slurry to avoid breaking of mature crystals into fines. By this, unwanted secondary nucleation and uncontrolled crystal growth can be reduced considerably.
Technoforce Plug Flow Crystallizer with cross section

By optimizing the crystallization process with our pilot size Technoforce Plug Flow Crystallizer, we were able to maximize yield with a narrow crystal size distribution for the monomer. The solution was directly coming from the upstream depolymerization at elevated temperature and was gradually cooled down at two different cooling media temperatures in one single TPFC. Thus, in one step we achieved the desired separation, while for demands of even higher purity it is always possible to repeat the crystallization by using either the same or a different solvent, a process known as re-crystallization.
In our laboratories in Nashik/India or Geleen/The Netherlands we can offer our customers bench scale and pilot scale crystallization trials in our continuous Plug Flow Crystallizers. Choice of suitable solvent as well as some pre-investigations regarding solubility curves should be performed by the customer beforehand to speed-up the project.
Technoforce has already designed and built several hundred skids of process intensification technology for oils and fats applications, fine chemistry, polymers, food and pharma products and other industrial sectors. We also offer other evaporation technologies like Short Path Distillation, Agitated Thin Film Evaporation and Drying, Falling Film, Rising Film and Forced Circulation Evaporation, as well as Liquid-Liquid Extraction in columns or centrifugal systems.