Background and general principles

Membrane gas separations

Figure 1 - Schematic diagram of a single-stage gas permeation process operating under steady-state conditions

Figure 2 - Experimental device used by Graham to measure the permeation velocities of pure gases in a natural rubber flask.

Figure 3 - Molecular transport mechanisms in porous and dense solids

Figure 4 - General problem of choosing a membrane material for separating a given binary mixture

Figure 5 - Examples of flat membrane structures

Figure 6 - Examples of hollow-fiber membrane structures

Figure 7 - Plan module (Sterling Fluid System and Hereon documents)

Figure 8 - Spiral module (MTR document)

Figure 9 - Hollow fiber module, (Air Liquide document)

Figure 10 - Tubular modules

Figure 11 - Pre-treatment/protection chain for a gas permeation device (Air Liquide document)

Figure 12 - Schematic representation of a steady-state gas permeation module

Figure 13 - Main flow patterns in gas permeation modules

Figure 14 - Gas permeation module for maximum permeate purity (ymax)

Figure 15 - Evolution of the permeate purity of a gas permeation module as a function of sampling rate and pressure ratio for a feed composition xin and an ideal material selectivity α* fixed.

Figure 16 - Calculating the energy consumption of a compression feed system

Figure 17 - Calculation of the energy consumption of a permeate vacuum system

Figure 18 - Cross-flow gas permeation module

Figure 19 - Simulation of the separation performance of a gas permeation module

Figure 20 - Examples of gas permeation cascades

Figure 21 - Overview of the various stages leading to a technico-economic analysis of a gas permeation process

Figure 22 - Example of purity (y)/fast compound recovery trade-off (also called yield R &#61; θ · y/xin) for a gas permeation module

Figure 23 - Examples of complex gas permeation behaviour

Figure 25 - Example of a process synthesis study for the production of nitrogen of varying purity levels by gas permeation

Figure 26 - Area of competitiveness for nitrogen production using different technologies (Air Liquide document)

Figure 27 - Process diagram for a gas permeation hydrogen purification unit

Figure 28 - Purification of natural gas by gas permeation

Figure 29 - Process diagram for the recovery of solvents or heavy hydrocarbons using a membrane system

Figure 30 - Helium recovery unit combining gas permeation and adsorption

Figure 31 - Selectivity/permeance trade-off curve for the CO2/N2 mixture (CO2 capture), showing the spectacular evolution in performance achieved compared with the first existing materials.

Figure 32 - MTR&#039;s CO2 capture pilot in a thermal power plant (MTR document).