Two-zone convective reformer for the decentralized production of H2/syngas from biomethane.

This study presents design results of two novel intensified convective reactors aimed at hydrogen/syngas production from biomethane. The first design (Design I) features a reactor housing two tube banks, operating at different temperature levels. The second design (Design II) advancing towards process intensification, incorporates palladium-based membranes in the low-temperature zone (LTZ). Superalloy tubes, capable to withstand high-temperature operating conditions, are disposed in the high-temperature zone (HTZ), while conventional stainless steel is profited for the tubes in the LTZ. These bayonet-type tube designs offer notable advantages in terms of energy integration, mechanical integrity, and reduced manufacturing costs. In both designs, the bayonet configuration in the HTZ enables a heat recovery of approximately 13.5 % from the returning syngas. The results demonstrate high methane conversions of about 76.41 % and 82.12 % for Design I and Design II, respectively. Hydrogen production yields ca. 524 Nm3/h for Design I and 567 Nm3/h for Design II, with H 2 /CH 4 yields of 2.62 and 2.83 kmol H 2 per kmol CH 4 feed, respectively. The incorporation of a Pd-based membrane in Design II allows the selective extraction of pure H 2 , resulting in an 8.28 % increase in H 2 production by shifting the thermodinamic equilibrium. The implementation of a membrane-based purification unit downstream the reactor aiming achieving pure H 2 would require an approximate membrane area of 14 m2 for both designs. Design II, when coupled with this downstream membrane module, would exhibit an increase of 10.64 % in pure hydrogen yield compared to Design I. [Display omitted] • Reactor with two zones: different materials of tubes in each zone. • Bayonet-type tubes allows enhanced energy integration and mechanical integrity. • +5 % in CH₄ conversion due to the use of palladium-based membranes. • Maximum H 2 production of 567.5 Nm3/h for Design II. [ABSTRACT FROM AUTHOR]