High pressure differential, ceramic membrane

Most oxygen-ion transport membranes operate in the temperature range 750 to 1000 °C. This creates several problems for operation of ceramic membranes. First, the membranes must tolerate a 20 bar pressure differential at temperatures that are conducive to generating creep-induced failure. The membrane materials which have high ionic conductivity also have large numbers of lattice vacancies to facilitate mobility of the ionic species, but lattice vacancies are major contributors to elevated creep rates. 

Membrane properties, as discussed in the previous section are typically measured in dense polymer film approaching one millimeter in thickness, less than 100 cm area, and supported on a porous ceramic or metal backing plate. Scale up of flat-fihn membranes to commercial scale has been quite Hmited, typically to applications involving small quantities of gas, low-pressure differentials, and to high flux, low selectivity membranes. 

The most commonly adopted filtering media is a high-density ceramic characterized by an asymmetric structure, a support material covered with a thin membrane layer containing very small pores. The membrane collects the fine particles and by making it thin the differential pressure of the filter element is kept low. The ideal solution is to have a very thin layer without defects that just covers the support material, so that purely surface filtration takes place. Experimental evidence at industrial scale shows that this ideal solution can be achieved in practice, penetration of particles into the support structure of the filter element being prevented, and that the element can be effectively regenerated by the clean gas back-pulsing procedure described by Cocco et al. [56]. It has also been confirmed at... 

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