Thawatchai Wongchang. Biomass based Hydrogen production enhancement and Tar reduction using high temperature Steam Reforming process. Doctoral Degree(Mechanical Engineering). King Mongkut's University of Technology North Bangkok. Central Library. : King Mongkut's University of Technology North Bangkok, 2012.
Biomass based Hydrogen production enhancement and Tar reduction using high temperature Steam Reforming process
Abstract:
This research investigates hydrogen production and tar reduction by steam
reforming process of syngas from biomass(sawdust) pyrolysis in a free fall reactor.
The aim of this work has been undertaken as part of the design of continuous
hydrogen production using the high temperature steam reforming process without
catalyst on steady state test conditions. The main research activities concentrated on
the parametric study of effecting parameters including: reforming temperature,
equivalence residence time and steam to biomass ratio(S/B). The main process step
involves the reaction of steam and syngas with temperature 600°C to 1200°C to form
hydrogen(H2) and carbon monoxide(CO) and also to suppress tar. The operating
temperature is a key factor in determining the extent to which H2 production is
increased at higher temperatures (900-1200°C) whilst maintaining the same
equivalence residence time and S/B ratio. During the steam reforming process,
methane(CH4) slightly increases when temperature was increased 600°C to 800°C.
Above 800°C, the volume of CH4 slightly decreased. Throughout the whole process,
CO and CO2 slightly increases as the temperature rises, where the volume of CO
higher than CO2at all experimental conditions. Both ethylene(C2H4) and ethane(C2H6) volume will slightly increase between temperature 600°C to 700°C, once surpass 700°C the volume will start to decrease consistently until 1100°C, where very little evidence of the ethylene and ethane compositions could be found. The results show that the use of syngas from biomass pyrolysis can produce higher hydrogen production from high temperature steam reforming
On tar investigation, it has been found that the reforming temperature; resident
time and steam to biomass ratio effected the tar reduction. The resident time have
strong effect on tar suppression than steam to biomass ratio at the same temperature.
At temperature higher than 1100°C, founded tar conversion to gas was 84-91%[wt].
Moreover, tar compositions have been studied. Aromatics compound groups will
slightly decrease consistently until 900°C where very little evidence of the
compositions could be found. In opposite, the increasing of polycyclic aromatic
hydrocarbons (PAHs) groups was favorited by the temperature higher than 900°C.
The high temperature steam not only increase reaction of syngas but also participate
in tar reduction and increase high hydrogen production with steam reforming and
water shift reaction. In future work, the increasing reformer efficiency needs to be
optimized for different operating conditions.