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Analys av koksresters rörelse i ett indirekt fluidbäddsförgasarsystem
2015 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

At Vienna University Technology a dual fluidized bed gasifier has been developed for biomass gasification. The solid residue from the gasification process, known as char, is transported via a chute from the gasification reactor to a combustion chamber where it is combusted. For this system, problems with low char movement to the combustion chamber have occasionally occurred. The purpose of this thesis has been to increase the understanding of char movements in this type of systems. The main objective has been to identify why this low char movement to the chute is occurring and which operating parameters that affects it. Some of the parameters tested were fluidization intensity, overall char concentration, amount of bed material and mass recirculation rate.The investigation was done experimentally with the use of a scaled cold flow model based on an 8 MW dual fluidized gasifier plant in Güssing, Austria. The thesis discusses the scaling procedure, the design of the cold flow model, the choice of parameters to be varied and a description of how the experiments were carried out. Necessary theory about biomass gasification, principles of fluidization and fluidized bed technology is provided for understanding of the problem and the experimental setup.From observations made during the experiments, it is concluded that the quality of the mixing in the gasifier mainly affects the char movement to the chute. It was found that increased fluidization intensity and lower overall char concentration is beneficial for improved mixing and thus increased char movement to the combustion chamber. Higher mass recirculation rates might be beneficial for improved mixing but has not yet been completely evaluated. The impact of increased amount of bed material in the system is still unclear.The work in thesis is a part of the gasification and fluidized bed research that is being carried out at Vienna University Technology.

Place, publisher, year, edition, pages
Keyword [en]
Keyword [sv]
Teknik, Fluidiserad bädd, kallflödesmodell, biomassaförgasning, Cold flow model
URN: urn:nbn:se:ltu:diva-57475Local ID: e22f5561-b9f4-44ea-ae87-f8dd5c9acc86OAI: diva2:1030862
External cooperation
Subject / course
Student thesis, at least 30 credits
Educational program
Sustainable Energy Engineering, master's level
Validerat; 20150715 (global_studentproject_submitter)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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Degerström, Peter

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