________________ Abstract  ________________

Biomass as a CHO complex contains about 6% of hydrogen by weight. Air gasification
has been practiced yielding about 40 grams of hydrogen per kg of biomass. The study
comprehensively addresses the oxy-steam gasification towards enriching the hydrogen
in the product syngas using experimental and model studies.

Using superheated steam and oxygen mixture as gasifying agent in a co-current
downdraft gasifier, a maximum of 104 g of H2 per kg of biomass has been achieved
with 51% volume fraction in dry syngas at steam to biomass ratio (SBR) of 2.7.
Syngas with LCV of 9 MJ/Nm3 is achieved at lower SBR, which is almost double the one
obtained through air gasification of dry biomass. H2/CO ratio of 1.5 to 4 has been
achieved by varying SBR from 0.75 to 2.7 which is critical for downstream processes
like FT synthesis, DME synthesis etc. One of an important aspect of Carbon boundary
has been identified and addressed for stable and sustained operating conditions for
oxy-steam gasification process.

Study also addresses the packed bed biomass gasification system modeling. Mass,
energy and species conservation equations are modeled with appropriate initial,
boundary and interface conditions. Model analysis has been accomplished using two
sub-models: single particle analysis and packed bed analysis. Modeling of single
biomass particles highlights the importance of the thermo-physical properties of
fuel and its influence on the overall biomass conversion profile. Modeling of the
reactor is configured as packed bed of particles with homogeneous reacting media and
analysis of heterogeneous reactions at the particle level. The numerical study
predicts output gas composition and flame propagation in the packed bed. The
experimental results are compared and analysed with results from the literature and
own experiments.

Carbon boundary phenomenon and variation in flame propagation rate experienced
during experimental investigation is further analysed using energy balance at the
particle level. New dimension of understanding has been proposed in the study
towards effect of reactants and reactant mass flux on the flame propagation rate in
a packed bed reactor and condition for sustainable operation. 
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Bio-sketch 

Dr. Sandeep Kumar did his B.Tech from NIT Silchar (Assam) from Mechanical
Engineering Department in 2003. He joined Infosys Pvt. Ltd. after his B.Tech and
worked in Bank of America online banking project as a Software Engineer and Analyst.
He left Infosys in 2007 to pursue his dream career in research and joined IISc
Bangalore for Master's program in Center for Sustainable Technology under the
research guidance of Dr. Dasappa. He converted his master's program to PhD in 2009.
After finishing his thesis work, he joined Thapar University (Patiala) as Faculty in
Mechanical Engineering Department in 2015. He is also associated with the School of Energy and Environment, Thapar University.