Steam reformer/catalytic combustor

An early application of a combined steam reformer/catalytic combustor on the meso scale was realized by Polman et al. [101]. They fabricated a reactor similar to an automotive metallic monolith with channel dimensions in the millimeter range (Figure 2.65). The plates were connected by diffusion bonding and the catalyst was introduced by wash coating. The reactor was operated at temperatures between 550 and 700 °C 99.98% conversion was achieved for the combustion reaction and 97% for the steam reforming side. A volume of < 1.5 dm3 per kW electrical power output of the reformer alone was regarded as feasible at that time, but not yet realized. 

First a 5 kW combined methanol steam reformer-catalytic combustor was built. The reactor was composed of modules ofthree types of plates forming a stack. Instead of microchaimels, fins served as mechanical support and improved heat transfer. A total of 225 plates were incorporated into the reactor. The reactor was designed for a maximum operating pressure of 4bar and 350 °C maximum reaction temperature. The experimental results presented were determined at a partial load of the device [1-2 kW for the lower heating value (LH V) of the hydrogen produced]. At a S/C ratio of... 

An integrated microstructured 5-kW combined methanol steam reformer/catalyt-ic combustor was fabricated and the results were presented by Hermann et al, from GM/OPEL [515]. The specifications for the reactor and a future 50-kW fuel processor system were fairly ambitious. Amongst others ... 

Subsequently, a meso-scaled combined reformer/catalytic combustor with 10-kW power output was realised by GM/OPEL, which was not presented in detail. For this bigger reactor, the carbon monoxide content of the reformate increased, as expected, with increasing reformer outlet temperature from 0.5% at 250 °C to 2% at 300 °C. Increasing the residence time increased the carbon monoxide concentration of the reformate due to the reverse water-gas shift reaction. Increasing the S/C ratio from 1.2 to 1.8 at a 300 °C reaction temperature increased the hydrogen concentration in the reformate slightly from 72 to 73% and decreased the carbon monoxide content from 1.5 to 1.0%, which originated from the beneficial effect of steam addition on the equilibrium of the water-gas shift reaction. 

The catalytic combustor provides heat for the endothermic reforming reaction and the vaporization of liquid fuel. The endothermic reforming reaction is carried out in a parallel flow-type micro-channel of the reformer unit. It is well known that the methanol steam reforming reaction for hydrogen production over the Cu/ZnO/AbOs catalyst involves the following reactions [10]. Eq. (1) is the algebraic summation of Eqs. (2) and (3). 

A device capable of processing various fuels such as methanol, octane and diesel was presented by Hu et al. (Figure 2.85) [132]. It was composed of a catalytic combustor feeding a separate steam reformer. Both devices were supplied by separate evaporators. 

K. Schubert, Micro-structured Methane Steam Reformer with Integrated Catalytic Combustor, Fuel Cells 2007, 2,... 

Casio Computer has developed a 2.4 We integrated micro fuel processor comprising a methanol steam reformer, a PrOx reactor and a catalytic combustor (Figures 27.10... 

Z Hsueh, C.-Y., Chu, H.-S., Yan, W.-M., and Chen, C.-H. (2010) Numerical study of heat and mass transfer in a plate methanol steam micro reformer with methanol catalytic combustor. Int. 

SOFC systems can be designed to include a heat recovery component such as an adsorption chiller heater for CHP applications [72-76]. An example is a small (1-lOkW) methane-fueled residential CHP SOFC system that integrates CGR, AGR, and internal reforming [73]. The system consists of a fuel-cell stack, steam prereformer, various fluid delivery devices (blowers, ejectors, compressor, and water pump), heat exchangers, and catalytic combustor and power conditioning device along with a heat recovery component. Based on certain system parameters (50active area, nominal cell temperature of 800 °G, current density of 0.57 A cm , power density of0.40-0.43 Wcm , S/G ratio of 2.0, SOFC... 

Figure 7.7 Cross-flow arrangement (left) of the plate-fin methanol steam reformer coupled with a catalytic combustor as developed by Pan and Wang [382] the diagram on the right side shows details of the gas distribution system, which was introduced into the combustor fixed-bed.

Park et ol. [507] increased the size of their methanol steam reformer described above to an electric power equivalent of 28 W and combined steam reforming with catalytic combustion The reactor was sealed by brazing. While the same steam reforming catalyst as described above was coated onto etched channels of200-pm depth and 300-pm width, the catalytic combustor was a small scale fixed-bed of platinum/alumina catalyst spheres... 

Cremers, C., Pelz, A., Stimming, U., Haas-Santo, K., Gdrke, O., Pfeifer, P. and Schubert, K. (2007) Micro-stmctured methane steam reformer with integrated catalytic combustor. Fuel Cells, 2, 91-98. 

A radial concept is used for the integration of the combustor and catalytic reactor where concentric functional chambers build outward from a central core (Figure 4). The innermost sections comprise the combustor unit, where air is carried to the interior and raffinate gas from the membrane penetrates through the wall to form a combustion flame along the itmer wall of the reaction chamber. Preheated and mixed steam and fuel enter the reaction chamber and are catalytically converted to reformate. Reformate exits the reactor and is then sent to the... 

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