Membrane Modules for Hydrogen Separation and Purification

In contrast, if the membrane is an inorganic composition (e.g., a dense metal membrane or a nanoporous ceramic membrane), the membrane module may be operated at the elevated temperature of 450 °C. In this case, there is no need for optional HEX 2 as the fuel gas stream will exit the membrane module at 450 °C and pass to the burner without further cooling. In addition to a net increase in overall process energy efficiency, the elimination of HEX 2 also represents a reduction in capital cost for the system. 

In comparison, a plate-and frame membrane module yields membrane packing densities in the range of several hundred square meters per cubic meter. For example, 

Module volume = 0.071 m3 (internal) Module length = 1.01 m (external) 

Membrane Diameter (mm) Number of Membranes Total Membrane Area (m2) Membrane Packing Density (m2/m3) 

Thicker, self-supporting, dense metal membranes are known. These are tubular and are usually lmm in diameter. The first commercially successful palladium-silver hydrogen separation membranes were of this type.21 Currently, Power and Energy, Inc. also fabricates this type of membrane, although planar membranes are more common due to easier fabrication and a greater variety of fabrication methods. 

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