(200c) Innovative Zoneflow® Reactor Technology- Gearing for Future in Steam Reforming for Hydrogen Generation

Gearing for Future in Steam Reforming for Hydrogen Generation

Sanjiv Ratan and Michael Ralston, ZoneFlow Reactor Technology (ZFRT)

Prof. Juray De Wilde, Universite Catholique de Louvain

The predominant technology for hydrogen generation over the past decades has been steam reforming of light hydrocarbons. This mature technology, however, has seen only incremental improvements in its catalyst along with superior tube metallurgy. With the steam reformer being the heart of a hydrogen plant carrying out the complex steam reforming reaction involving heat, mass and momentum transfer, its reforming catalyst plays a critically important role in its thermal design, performance, reliability and cost-effectiveness.

The conventional "pellet" steam reforming catalysts suffers from inherent limitations and/or operational deficiencies. These mainly relate to a) uneven random packing voidage leading to undesired flow and temperature mal-distribution, b) catalyst attrition and breakage from thermal cycling leading to increasing pressure drop and related capacity limitations and c) pore-diffusion limited reaction path leading to curtailed intrinsic activity and lower resistance to carbon formation.

Past attempts to develop structured steam reforming catalysts to overcome some of these limitations have suffered from the innate problems around differential expansion gaps leading to feed by-passing and disturbed boundary layer endotherm, as well as from the reaction hydraulics being away from the tube wall, lacking required heat input, thus leading to insufficient conversion and hotter tubes.

ZFRT has developed and demonstrated its radically innovative proprietary structured catalyst design called the ZoneFlow^â„¢ Reactor (ZF Reactor) as a breakthrough technology that not only overcomes the above-mentioned deficiencies but also offers an unmatched combination of lower pressure drop with enhanced heat transfer. The ZF Reactor's unique structure provides the proximal flexibility which avoids the differential thermal expansion gaps, and also carries high physical strength against any breakage over its lifetime. Its nested modules provide much more geometric surface than pellets, and take away the diffusion-limited access to the layered active sites, resulting in higher intrinsic activity and also increased resistance to carbon formation compared to pellets.

ZF Reactor's performance parameters have been validated through advanced CFD analysis, followed by extensive pilot plant testing under commercial operating conditions. ZF Reactors also offer the advantage that they can be loaded horizontally, which allows for in-situ "convective pre-reforming" in the reformer convection section. Furthermore its annular casing design directly enables regenerative or "bayonet" reformer designs, while overcoming the major concerns and risks associated with the current pellet-based designs.

These features of the ZF Reactor can translate into attractive benefits to the end-user ranging from relieving "stressed" reformers, extending reformer tube life and capacity revamps to lowering SMR related Opex and Capex, covering large to small distributed hydrogen plants for fuel cells and futuristic hydrogen energy landscape. This paper will provide details of the ZF technology development and the pilot test results as well as various case analyses for enhanced economics of hydrogen generation.