Process Design

The analyses and design of the advantages of the application of membrane technology in (chemical) processes and energy systems are the essential guides for the strategic directions of the research program within the Membrane Technology group. However, we offer our competence also to third parties in the form of contract research. Where appropriate, these analyses are carried out in cooperation with universities and industry.

Issues related to this competence are:

• Process modeling and evaluation, including model development
• Process economics
• Feasibility studies, both technical and economical including energy analysis
• Technology assessments

For process analysis, both in-house developed spreadsheet models and commercially available software like MathCad (general calculation tool), AspenPlus (flow sheeting, design and analysis of chemical processes), EXERCOM (exergy analysis for AspenPlus) and @Risk (uncertainty analysis) are being used. FORTRAN coding or ASPEN CUSTOM MODELLER are available to implement descriptions of unit operations that are not standard in AspenPlus, like membrane models for nanofiltration, pervaporation or gas separation.

These activities are performed in close collaboration with the Process and System Technology group.

Flow sheeting calculations

By ASPEN+ flow sheeting it is possible to solve all mass and heat balances of a process and to pick up the necessary physical properties, both for existing unit operations and for the plugged in membrane unit operation. Descriptions of pervaporation membranes for e.g. the dehydration of organic mixtures, for ammonia separation membranes and for hydrogen separation membranes (also as membrane reactor) are available in ASPEN+. The models and process flow sheets are used for performing the process evaluation of e.g. an existing process and the process including the membrane operation. Sensitivity analysis is used to finding the optimum process configuration and a technical comparison of the processes is made. The calculated membrane area, sizes of unit operations and needed utilities are used for detailed cost calculations. In house developed cost models and existing data bases and literature are used as input as well for making an economic comparison between the existing process and the new membrane based process.

Model development for process calculations

For the simulation of a membrane based process in the flow sheeting program ASPEN+ no description of the unit operation is commercially available. We have developed such a description starting from the basic mathematical equations describing the membrane performance, e.g. the membrane flux or permeance and the membrane selectivity. Descriptions of the flow profile in the membrane module or the combination of membrane modules are then made based upon chemical engineering calculations to describe the module performance. The membrane unit operation is then linked to the flow sheeting program ASPEN+.