In an extruder reactor (see Fig. 6a), the extruder transports the material and additionally causes stirring, thereby improving vapour and heat transport. The effectiveness of the transport depends on the rotational speed of the screw. The heat can be added or removed by means of either a jacket around the screw tube, or a hollow screw. This would be a convenient way of integrating the means of transport required for the powder and the reactor. If there is risk of the TCM material sticking to the screw, a system with two parallel self-wiping screws may be applied.

700 600 500

*

400 300 200 100 0

Fig. 6. (a) TCM extruder reactor, (b) extruder heat transfer (Jephson model, in (Kalbasenka, 2008))

For the case of dehydration of the TCM, assuming that the heat transport would be the limiting factor for the power, for a 3kW reactor and an effective heat transfer to the wall of about 550 W/m2K, this would lead to a reactor of about 1 m in length and 5 cm diameter, in which about 75% of the open volume would be filled with TCM.