Gas separation process and plant with capacitive membranes

The invention relates to a new process for the separation of components in gaseous stream, for applications in the purification of gas or in the capture of specific components in gas streams.

Title of the patent Alternating potential gas separation process with capacitive membranes, and relative plant
Thematic area Chemistry and biotechnology
Ownership Alma Mater Studiorum - Università di Bologna and National Research Council
Inventors Ferruccio Doghieri, Elena Landi, Valentina Medri, Francesco Miccio, Matteo Minelli, Giulio Cesare Sarti
Protection Italy
Licensing status Available for licensing agreements
Keywords Gas separation, Capacitive membranes, Dense/porous bilayer membrane, Continuous operation, Pseudo-steady state
Filed on Jul 23, 2015

The current processes for membrane separation of gas stream are currently conducted in stationary conditions, at constant potential. The input flow is divided into two currents of equal phase, a retentate which is collected upstream of the membrane and a permeate collected downstream. These processes are realized by use of membranes, and the resistive characteristics of the membrane play a significant role in determining the performance of the process.

The invention consists of a process and a plant, which allows to achieve an effective separation of currents in the gas phase or vapor. The method takes advantage of the capacitive characteristics of the membranes and acts on the permeate flow managing variables that determine the potential of the separation.

The new proposed process can be applied to the separation of components in the gas phase in order to purify contaminated currents or capturing / retrieve specific substances contained in effluents or process streams. Compared with the current processes of membrane separation, this innovation allows to obtain much higher selectivity at constant overall permeance while maintaining the continuous mode of operation, as well as the characteristics of modularity and compactness of the apparatus.

The invention allows:
- Get much higher selectivity for the same permeance overall;
- Significantly improve the separation factors without reduction in productivity;
- Operate with continuous mode of operation;
- Set to values other than the performance of the process (recovery factor and purity of the permeate) in a wide range, by acting on the internal parameters of the process, with no changes in plant and for the load (flow rate, condition and composition of the feed stream) unchanged;
- Preserve the characteristics of modularity, simplicity and compactness of the equipment, resulting in lower investment costs;
- Avoid the presence of moving parts, and alternating between running on the same path, what a positive impact on reliability, capacity, operating costs and maintenance.