High-temperature steam reforming insulation

The CSP plant consists of a solar collector field, a receiver, a heat transfer fluid loop and a heat storage system. The mirrors of the solar field concentrate the direct solar radiation on the solar receiver set at the focal line. The heat transfer fluid (e.g., molten salts) removes the high temperature solar heat from the receiver that is afterwards collected into an insulated heat storage tank to be pumped, on demand, to the heat users (steam generators, endothermic reactors, etc.), where its sensible heat is released. Finally, the heat carrier fluid is stored in a lower temperature tank ready to restart the solar heat collection loop. The idea to match the CSP plant with natural gas steam-reforming Pd-based MR derives from the thermal level reached by molten salt stream (550°C), which meets the thermal requirements of MR (preferred operating at around 500°C). 

Lee et al. [58] from Samsung reported development of a fixed-bed natural gas reformer coupled to a WGS reactor with an electrical power equivalent of 1 kW. The steam reformer was placed in the center of the subsystem, while the annular WGS fixed bed surrounded the reformer separated by an insulation layer. Commercial ruthenium catalyst served for steam reforming, while a copper-based catalyst was used for WGS. A natural gas burner supplied the energy needed by steam reformer. The reformer was operated between 850 and 930 C, while the shift reactor worked between 480 and 530 C. The carbon monoxide content of the reformate was reduced to 0.7 vol.% downstream the shift reactor despite its high operating temperature, because the reformer was operated at high S/C ratio between 3 and 5 the water surplus affected the equilibrium of the WGS reaction positively. At full load, the efficiency of this subsystem was 78% which decreased to 72% at 25% load. 

High preheat temperatures for feed and combustion air lead to reduced fuel consumption and thereby to savings, especially when the steam production in the plant must be minimized. Reduction of the flue gas stack temperature reduces the heat loss to the atmosphere. A similar effect has, perhaps more importantly, been obtained by improved insulation in the reformer. 

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