Experimental and numerical investigation of a two-stage downdraft biomass gasification process
(2018)
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- Authors
- Supervisors
- Jeanmart, Hervé
- Abstract
- The amount of tar in the producer gas is the main drawback for the indus- trial development of biomass gasification facilities. Recently, successful designs, based on the two-stage concept from the Asian Institute of Technology (AIT) and the Danish Technical University (DTU), have been developed for small- scale applications. In such facilities, very low tar levels are achieved. The present work focuses on a two-stage technology presenting a physical sep- aration between the pyrolysis and the oxidation/reduction zones. The air is injected in two separate inlets like on the AIT design with part of the air being injected at the pyrolysis level and part being used for the oxidation. The main evolution is the physical separation of the pyrolysis and oxidation/reduction zones as in the DTU design. It allows an independent control of the pyrolysis and the tar oxidation and cracking in a gaseous zone. This thesis presents the experimental results obtained on a research gasifica- tion plant with a thermal power of 200 kW. The influence of several parameters on the performances of the process have been investigated, among them : the air ratio, the bed heights and porous medium injection in the pyrolysis zone. Aside from those results, the use of gasifying agents other than air in order to modify the characteristics of the producer gas is also discussed. This study also presents experiments on the influence of different biomass feed- stocks since the future of gasification may reside in energy recovery from wastes. The experiments performed with waste biomass highlighted the importance of the pyrolysis zone in the gasification process. Further experimental investiga- tions were performed on the pyrolysis zone using natural wood. In parallel, a model combining a wood particle model (based on the work of Julien Blondeau) with a 2D axisymmetric reactive simulation of the pyrolysis zone was developed using ANSYS Fluent®. The model can help to predict the influence of the feedstock on the tar level at the end of the pyrolysis zone that can be linked to the tar level at the outlet of the gasifier.
- Affiliations
Citations
Berger, B. (2018). Experimental and numerical investigation of a two-stage downdraft biomass gasification process. https://hdl.handle.net/2078.5/48434