Cfd Simulation Study of The Novel Multistage Inlet Gasifier For Enhancement of Syngas Production

Abstract

Economically, fossil fuels remain the main source of energy despite their
high emissions of greenhouse gases. However, biomass, a renewable fuel with CO2
neutrality, has experienced widespread attention as a potential contributor to the
sustainable development of the energy sector. Gasification is an important
thermochemical process that converts biomass feedstock into H2-rich combustible
gases known as syngas. Its main product (syngas) can be used as fuel in various
conversion technologies to produce different products, including electricity and
chemicals. This research study focuses particularly on biomass gasification that is a
promising technology to achieve high-quality syngas in the presence of one or more
gasification agents. To accomplish this aim, a single-stage and two-stage downdraft
reactor are analysed in this study using an equilibrium model with non-premixed
combustion in the ANSYS Fluent. This study shows that the CFD model simulated
values of outlet gas composition was in good agreement and was validated with the
Paul1 model prediction and experimental data2. The highest temperature inside the
gasifier for a single stage model is found in the oxidation zone, where the air is
supplied. The temperature in the drying zone is less than 460K, in the pyrolysis zone
is between 470 and 455K, in the oxidation zone is between 470 and 490K, and in the
reduction zone is between 480 and 485K. The highest temperature inside the gasifier
for a double stage model is found in the oxidation zone, where the air is supplied. The
temperature in the drying zone is less than 470K, in the pyrolysis zone is between 470
and 480K, in the oxidation zone is between 470 and 520K, and in the reduction zone
is between 480 and 485K. It is observe that the CO and H2 concentrations are higher
in the pyrolysis zone for single and double stage as the volatile matter turn to gases
phase due devolatilization process. Then for CH4 mole fraction, the single stage was
0.06% while the double stage was 0.03%.3 reported CH4 values similar to those found
in this study. It is demonstrated the advantages of the double stage by supply air in
gasification experiments in a downdraft gasifier.