Steam reforming reactor design

Traditionally, the steam reforming reactor has a tubular design in which vertical tubes, loaded with catalyst, are surrounded by furnaces to supply the heat required for the strongly endothermic process, see Fig. 8.2. Combustion of natural gas supplies the heat to the tubes. 

The reduction of operating temperature drives the plant designers to find new and better solutions to supply heat duty to steam reforming reactors, exploiting, for example, heat streams from other parts of industrial plants. 

Hotz et al. compared the efficiency of a small PEM fuel cell system, which had a methanol fuel processor composed of a fixed-bed steam reformer and preferential oxidation reactors, with a direct methanol fuel cell system [439]. Both systems were in the power range of 2 Wei. The steam reformer was designed as a tubular bundle filled with copper/zinc oxide catalyst, operated at a S/C of 1.1 and heated by the combustion gases of the afterburner. Because the methanol conversion was assumed to be only 45%, most of the methanol was combusted in the afterburner, which generated sufficient energy to keep the system on temperature. However, the efficiency of such a system will be low. The exergetic efficiency (which is in fact the system efficiency as defined in Section 2.2) ofthe fuel processor/fuel cell system was calculated to be 30%. 

Figure 9.37 Design concepts of IdaTech steam reformers left, tubular fixed bed steam reformer reactors are placed around a central burner right, heat-exchange reformer the pre-reformer is placed in the outer area ofthe device while the reformer is more in the centre the combustion gases ofthe homogeneous burner pass through several annular gaps between the annular catalyst beds for heating [105].

In this study, we developed microchannel PrOx reactor to control CO outlet concentrations less than 10 ppm from methanol steam reformer for PEMFC applications. The reactor was developed based on our previous studies on methanol steam reformer [5] and the basic technologies on microchaimel reactor including design of microchaimel plate, fabrication process and catalyst coating method were applied to the present PrOx reactor. The fabricated PrOx reactor was tested and evaluated on its CO removal performance. 

Most industrial hydrogen is manufactured by the following hydrocarbon-based oxidative processes steam reforming of light hydrocarbons (e.g., NG and naphtha), POx of heavy oil fractions, and ATR. Each of these technological approaches has numerous modifications depending on the type of feedstock, reactor design, heat input options, by-product treatment,... 

Arana et al. have performed extensive modeling and thermal characterization experiments on their reactor design. They modeled their design consisting of two suspended SiN - tubes linked with slabs of silicon using two-dimensional computation fluid dynamics and a heat transfer model (Femlab, Comsol Inc.). The heat of reaction of the steam reforming or... 

For reformate flow rates up to 400 Ndm3 min-1, the CO output was determined as < 12 ppm for simulated methanol. The reactors were operated at full load (20 kW equivalent power output) for -100 h without deactivation. In connection with the 20 kW methanol reformer, the CO output of the two final reactors was < 10 ppm for more than 2 h at a feed concentration of 1.6% carbon monoxide. Because the reformer was realized as a combination of steam reformer and catalytic burner in the plate and fin design as well, this may be regarded as an impressive demonstration of the capabilities of the integrated heat exchanger design for fuel processors in the kilowatt range. 

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