1000 K

the total net specific consumption is exclusively dictated by stoichiometiy (0.33 Nm3CHVNm3H2) which for a specific CH4 conversion of 90% turns to be 0.36 Nm3 CH4/Nn?H2. Moreover, it is important to stress that this specific consumption is, by definition, insensitive to the size and this allows to anticipate a flexibility, as to the size of the fuel processor modules required, totally lacking in conventional steam reforming. From the above it is evident that the CSPOM allows a saving with respect to conventional SRM, varying, depending upon the size, from 12 to 20 % in the fuel consumption per unit CO and H2. If the comparison is restricted to the small sized plants (50-200 Nm3/h), a sound estimate is, at least, a 15 % saving.

The comparison in terms of productivity is also in favour of the CSPOM. As typical contact times for total conversion of CH4 are in the order of 0.04 sec, a productivity of 0.3 - 0.5 mol CH4 conv./kg cat sec is expected, which is at least one order of magnitude higher of that reported for most efBcient SRM plants. Therefore it could be anticipated that CSPOM will demand reactor's sizes at least one order of magnitude smaller, with inherent savings in investments which preliminary estimates assume to be in the order of 30 %. Technical benefits, as above, should be weighted, in turn, in terms of a lower, likely 20 % lesser emission of CO2 per unit energy produced and, on the side of investments, in lower amortization rates with the added benefits of an easier workability and a more compact assembly bound to the adiabatic vs. the tubular configuration.

Besides, because of its lower heat entalpy, promptness to start-up and shut-down in CSPOM is expected to be higher and to follow better the changes in the load of the fuel cell subsystem. It should be noted that the theoretical debit for using 50 % syngas rather than 100 % (due to the use of air) results in a loss of only 15 mV in open circuit potential, a trivial disadvantage. Furthermore, as the adiabatic characteristics of a CSPOM reactors would demand less stringent engineering geometry and regulations, a wide "degree of freedom" in the modularity of use is expected, making possible to respond to whatsoever site-specific needs. Summing up main features, the advantages of CSPOM vs SRM could be anticipated as following (Table II).

Table II: Synoptical view of advantages and saving in CSPOM vs SRM (in arbitrary units).
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