Background

The equilibrium position of a polycondensation reaction can be shifted towards higher conversion rates by removing water. Within an industrial project at IMVT, the possibility of a continuous removal of water during the polycondensation of sugars using porous membranes is investigated. The water is to be separated in gaseous state through the pores of a hydrophobic membrane.

Membrane distillation is a technique of separating water vapour from a liquid flow through hydrophobic membranes. The driving force of the process is the difference in water partial pressure between the aqueous feed solution and a dry gas in the permeate side. So far, this technique has been used for temperatures below 100°C. The polycondensation reaction takes place at temperatures higher than 100°C. Mass transport as well as heat transfer processes in the feed and permeate side and through the membrane pores play an important role during the process [1].

Figure 1: Overview of the process

Figure 2: Membrane test cell for the experiments

Tasks / planned work

Within the scope of the work, the separation of water vapour from pure water as well as from sugar solution of different concentrations should be experimentally investigated.

Tasks of the work are:

• Literature research
• Start-up of the plant: Validation of the test stand and the measuring technique
• Experimental investigation of the water vapour separation for different process configurations (temperature of the flows up to 120°C, system pressure, velocity, pore size, concentration of the feed).
• Written summary of results

Conditions:

• Chemical engineering / process engineering students.
• The results of the work are summarised in a written paper and presented within an institute seminar.
• The thesis can be written in English or German.
• Starting date: immediately

Examiner:            Prof. Dr.-Ing. habil. Roland Dittmeyer
Supervisor:          Sara Claramunt
Contact:               sara.claramunt∂kit.edu
Tel:                        0721/608-24052

Sources:

[1] A. Mourgues, N. Hengl, M.P. Belleville, D. Paolucci-Jeanjean, J. Sanchez, Membrane contactor with hydrophobic metallic membranes: 1. Modeling of coupled mass and heat transfers in membrane evaporation, Journal of Membrane Science, Volume 355, Issues 1–2, 2010, Pages 112-125, ISSN 0376-7388, https://doi.org/10.1016/j.memsci.2010.02.040.