Institute of Chemical Engineering
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G-volution II – Next Generation Dual Fluidized Bed Steam Gasifier, Construction of a new 100 kWth Scientific Test Facility

Fig.1: Novel gasification reactor system, points of product gas sampling (Source: Schmid et al. EUBCE 2016)


Efficient utilization of biomass as a primary energy source reduces greenhouse gas emissions and reduces the need for long-distance transport of energy, thus increasing the security of energy sup-plies. The main challenge is to develop new fields of application apart from simple heat generation. In this area, the dual fluidized bed steam gasification technology developed at Vienna University of Technology and successfully demonstrated in Güssing at a scale of 8 MWth represents a key technology for both efficient combined heat and power production as well as for coupled production of synthetic biofuels (2nd generation biofuels, polygeneration approach). Various syngas upgrading and utilization technologies are currently investigated in national and international research projects. Some technologies, like production of synthetic natural gas are already in the large scale demonstration phase. An increased interest from industry in technologies to substitute natural gas by using industrial waste fuels such as sewage sludge, municipal waste, saw dust, bark, waste wood, etc., leads to a renaissance of research regarding the gas generation section itself.

In the classical design of the Güssing gasifier, the gasification reactor is designed as bubbling fluidized bed. The heat transfer to the fuel particles and the main tar destruction reactions take place in contact with the bed material particles inside the bubbling fluidized bed. Above there is a freeboard region where the solids concentration approaches zero. Such a separation between bubbling bed and freeboard leads to problems especially when inhomogeneous fuels are used. Organic fines are immediately elutriated into the freeboard where primary tars are emitted and not sufficiently converted due to lack of catalytically active solids in the freeboard. This may result in tar depositions down-stream of the gasifier and may critically affect the plant availability.

Recent research performed in the field of chemical looping combustion revealed that there is a significant improvement of gas-solids contact possible by increasing the fluidization velocity up to the turbulent or fast fluidization regime. In this case the bed material is distributed over the whole gasifier volume, partly elutriated at the top and recycled into the gasifier via a cyclone and loop seal. The change in fluidization conditions of the gasifier results in advantages.

The aim of G-volution II is to investigate this promising approach at relevant operating conditions to provide the basis for the industrial demonstration. The very promising results of the project G-volution (Neue Energien 2020, FFG-Projectnumber: 821954) will be implemented.

In a first work package, the detailed engineering for the 100kW process development unit will be performed. Work package 2 deals with the construction and work package 3 with the commissioning of this plant. Excessive test campaigns with the previous 100kW gasifier at Vienna University of Technology are an important basis for the engineering. Moreover, the operational range will be determined. The fluid dynamical feasibility will be demonstrated. A special focus will be drawn on the fuel flexibility of the system (with regard to composition of the fuel as well as its particle size distribution). The first work package contains also the development and installation of a scaled cold flow model of the G-volution gasifier. Extensive experiments will lead to design data of the hot test rig. Work package 4 deals with accompanying modelling and simulation for an accurate evaluation and interpretation of the experimental results as well as to create a validated parameter model for the basic and detailed engineering of future gas generation plants.

Fig.2: Time course of temperatures in the gasification reactor for a typical gasification test run with a variation of the fuel input power (Source: Schmid et al. EUBCE 2016)
Fig.3: Temperature variation, gasification of wood with pure olivine sand as bed material (Source: Schmid et al. EUBCE 2016)
Fig.4: Tar reduction and impact on the gaseous product gas comonents due to the upper countercurrent gasification reactor (Source: Schmid et al. EUBCE 2016)
Fig.5: Pressure profile of the dual fluidized bed gasification reactor system (Source: Pasteiner 2015)
Fig.6: product gas comosition - calcium oxide as bed material for the gasification of soft wood, sugar cane bagasse and lignite (Source: Benedikt, Schmid & Hofbauer, Minisymp.VT 2017)
Fig.7: Tar content - calcium oxide as bed material for the gasification of soft wood, sugar cane bagasse and lignite (Source: Benedikt, Schmid & Hofbauer, Minisymp.VT 2017)

Industrial Partner & Financial Support

The present project has been supported with financial contribution from the Austrian "Climate and Energy Fund" as a part of the research program "Neue Energien 2020":

Additional information about the project:

Contact:

Univ.Ass. Dipl.-Ing.(FH) Dr.techn. Johannes Schmid

Research Team:

Walter Tesch

Christina Hafner

Kristina Sternig

Alexandre Pazos Costa

Klaus Jörg

Roland Diem

Maximilian Kolbitsch

Stefan Müller

Michael Fuchs

Hermann Hofbauer

Michael Weitzer

Martin Hammerschmid

Herbert Pasteiner

Stefan Koppatz

Christoph Pfeifer

Project status:

Finished, report published