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The cooperative project OXYCOAL-AC aims at the development of a zero-CO 2 -emission coal combustion process for power generation. The scope of the research comprises a multitude of aspects. This article focuses on membrane-based air separation modules and their design for oxycoal conditions, the specifics of coal combustion in a CO 2 /O 2 atmosphere including related burner design as well as the cleaning of hot flue gas from oxycoal combustion.

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In the last years, a lot of ceramic materials were developed that, at higher temperatures, have a high electrical conductivity and a high conductivity of oxygen ions. Such mixed ionic/electronic conductors can be used to produce high‐purity oxygen. This work focuses on the realization of a pilot membrane module, with BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3‐δ) perovskite selected as the membrane material. An amount of 500 kg of powder was industrially fabricated, spray‐granulized and pressed into tubes. The best operation conditions concerning energy consumption were calculated, and a module reactor was designed operating at 850 °C, with an air pressure of 15–20 bar on the feed site and a low vacuum of about 0.8 bar on the permeate site. Special emphasis was placed on joining alternatives for ceramic tubes in metallic bottoms. A first laboratory module was tested with a membrane area of 1 m2 and then advanced to a pilot module with 570 tubes and a capability of more than 300 000 L of pure oxygen per day.

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Oxygen permeability measurements of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−ı (BSCF) disk shaped membranes fabricated by thermoplastic processing and sintered at different temperatures (1000-1100• C), showed no influence of the grain size on the oxygen permeation fluxes. To further investigations, Electron Backscattered Diffraction (EBSD) and Conductive mode (CM) microscopy methods were used for texture analysis and observation of the local electrical behavior in the BSCF membranes, respectively. EBSD results revealed that the grain size of the membranes increased with increasing the sintering temperature from an average of 3.32 m at 1000• C to 18.25 m at 1100 • C. Also, it was seen that there was no textural difference between the different samples. CM analysis demonstrated that the electronic conductivity of the grains and grain boundaries was similar in the membrane sintered at 1000• C. Finally, the stability of the membrane under the operation conditions was tested, and it was found that the permeation flux was nearly constant at 900• C after an operation time of more than 50 h, whereas oxygen permeation flux declined after a relative short time at 825• C.

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