Paper details

Title:

Modelling of a Traveling Bed Biomass Gasifier

Author(s):

Marias, F., Bernada, P., Deydier, A., Couture, F., Michon, U.

Document(s):

Abstract:

This work deals with the modelling of a travelling bed biomass gasifier. This gasifier is a part of a more general process devoted to the production of electricity from biomass. In a first stage biomass is dried and gasified in a travelling bed gasifier using air with an equivalence ratio of 0.3. This product gas contains light hydrocarbons as well as tars. It is converted into a syngas free from tars in a specific reformer (Turboplasma©) that uses plasma technology in order to raise the temperature of the incoming gas to a value compatible with thermal cracking of tars. The model of the travelling bed gasifier is based on the coupling between a software devoted to the description of the chemical and physical processes occurring within the travelling bed, and a CFD package (Fluent™) that allows for the description of the homogenous gas reaction and radiation occurring within the freeboard of the bed. The first software is a “home made” software based on the conservation equations of the solid, liquid and gas phases as well as of the energy. The balance equations are firstly written at the “phase scale”, and then, using a homogenisation technique (volume averaging) balance equations are derived at a representative volume scale. In this first work, this model is written using a one dimensional formalism along the axis of the travelling bed. Wood is used as a case study material with a pyrolysis mechanism that uses three parallel reactions leading to the formation of gas, tars and char. The gas and tars produced during the pyrolysis step can be converted within the bed itself but also over the freeboard of the bed. Hence, the free board of the bed is used as a boundary condition of the CFD domain, with known local mass flow­rate, composition and temperature. This study allows for a complete and precise description of the processes occurring within the gasifier under consideration.

Keywords:

biomass, gasification, modelling, modeling

Topic:

Thermochemical conversion - Gasification for power and CHP and polygeneration

Subtopic:

Gasification for power and CHP and polygeneration

Event:

18th European Biomass Conference and Exhibition

Session:

VP2.1.7

Pages:

640 - 648

ISBN-13:

978-88-89407-56-1

ISBN-10:

88-89407-56-5

Paper DOI:

10.5071/18thEUBCE2010-VP2.1.7

Price:

FREE