Wood Gas Processing To Generate Pure Hydrogen Suitable for PEM Fuel Cells

A test campaign was carried out to
generate renewable hydrogen
based on wood gas derived from the commercial biomass steam gasification
plant in Oberwart, Austria. The implemented process consisted of four
operation units: (I) catalyzed water–gas shift (WGS) reaction,
(II) gas drying and cleaning in a wet scrubber, (III) hydrogen purification
by pressure swing adsorption, and (IV) use of the generated biohydrogen
(BioH2) in a proton exchange membrane (PEM) fuel cell.
For almost 250 h, a reliable and continuous operation was achieved.
A total of 560 (Ln dry basis (db))/h of
wood gas were extracted to produce 280 (Ln db)/h of BioH2 with a purity of 99.97 vol %db. The catalyzed WGS reaction enabled a hydrogen recovery of 128%
(ṅBioH2)/(ṅH2,wood gas) over the whole process chain.
An extensive chemical analysis of the main gas components and trace
components (sulfur, CxHy, and ammonia) was carried out. No PEM fuel cell poisons were
measured in the generated BioH2. The only detectable impurities
in the product were 0.02 vol %db of O2 and 0.01
vol %db of N2.