Reformer electrical heated

Heinzel et al. [77] compared the performance of a natural gas autothermal reformer with that of a steam reformer. The ATR reactor was loaded with a Pt catalyst on a metallic substrate followed by a fixed bed of Pt catalyst. In the start-up phase, the metallic substrate was electrically heated until the catalytic combustion of a stoichiometric methane-air mixture occurred. The reactor temperature was increased by the heat of the combustion reaction and later water was added to limit the temperature rise in the catalyst, while the air flow was reduced to sub-stoichiometric settings. With respect to the steam reformer, the behavior of the ATR reactor was more flexible regarding the start-up time and the load change, thus being more suitable for small-scale stationary applications. 

Electrical heating requires power supply by an interim storage device, i.e. a battery. Even though batteries exist as buffer devices in most fuel cell system concepts, their size would need to increase considerably to meet the demands for start-up. Therefore, battery power is a less viable option especially for hydrocarbon reforming systems, where high operating temperatures of the reformer exceeding 600 °C need to be achieved. 

Methanol Steam Reforming 1 [MSR 1] Electrically Heated Serpentine Channel Chip-like Reactor... 

Methanol Steam Reforming 3 [MSR 3] Electrically Heated Stack-like Reactor... 

Figure 2.4 (a) Schematic exploded view of an electrically heated micro reformer and (b) a photograph of the mounted and welded device [13] (by courtesy of Springer VDI Verlag). 

Methanol Steam Reforming 6 [MSR 6] Electrically Heated Screening Reactor... 

A combined evaporator and methanol reformer was developed by Park et al. [124] to power a 5 W fuel cell. However, the device was still electrically heated by heating cartridges. Both the evaporator and the reformer channels, which were identical in size, were prepared on metal sheets 200 pm thick by wet chemical etching. The channel dimensions were length 33 mm, width 500 pm and depth 200 pm. Therefore, the channels were completely etched through the sheets and the channel depth could be varied by introducing several of these sheets into the reactor. The flow distribution between the 20 channels of the device was performed by triangular inlet and outlet fields. Both devices had outer dimensions of 70 mm x 40 mm x 30 mm. 

Pfeifer, P., Schubert, K., Liauw, M.A., Emig, G., Electrically heated microreactors for methanol steam reforming, Trans. IChemE 2003, 81A, 711-720. 

Possibility to supply heat directly to the catalyst by using the strings onto which the catalyst material is fixed as electrical heating elements. Clearly this feature can be exploited for quick startup of reactors and for highly endothermic reactions. This enables, for example, the steam reforming of methane in a very compact, electrically heated BSR. 

The studies were conducted in stainless steel tubular reactors approximately 3.8 cm in diameter and about 1200 cm3 in volume. The reactors were immersed in electrically heated fluidized solids baths. A naphtha fraction to be reformed was vaporized and heated to reaction temperature before contacting the catalyst. The reactor effluent was separated into liquid and gaseous fractions. A portion of the hydrogen-rich gaseous fraction was recycled through the reactor to simulate commercial reforming practice. The recycle gas was combined with the vaporized naphtha fraction prior to the reactor inlet. The mole ratio of recycle gas to naphtha at the reactor inlet was approximately 7 in all of the runs to be discussed here. 

Methanol is a liquid fuel that is readily dispensed and stored but, compared with conventional liquid fuels, is by no means ideal it is both toxic and water-miscible and has an energy content per litre that is well below that of petrol see Table 1.4, Chapter 1. A further drawback of incorporating a reformer into the vehicle is the need to supply heat for its operation. At 80-90 °C, the waste heat from the fuel cell would be inadequate and it would be necessary to burn some of the methanol to provide the heat or to use electrical heating. Either of these two options would obviously reduce the effective efficiency of the fuel-cell system. Altogether, on-board methanol reformers pose as many engineering problems as on-board hydrogen storage. Furthermore, the combined cost of a reformer and a fuel cell is likely to prove prohibitive, at least for small vehicles such as cars. 

Based on the type of thermal destruction process selected, there are several different commercial designs and configurations of the reactor that have been utilized for a particular application. Some of the most commonly used technologies include rotary kilns, starved air incinerators, fluidized beds, mass-bum incinerators, electrically heated reactors, microwave reactors, plasma, and other high-temperature thermal destruction systems. Recent advances include gasification and very high temperature steam reforming. 

Men et al. reported the operation of a small-scale bread-board methanol fuel processor composed of electrically heated reactors [15]. A methanol steam reformer, two-stage preferential oxidation reactors and a catalytic afterburner were switched in series. A fuel cell equipped with a reformate-tolerant membrane, which had a 20 W nominal power output, was connected to the fuel processor and operated for about 100 h. 

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