Gasification of lignite in a dual fluidized bed gasifier — Influence of bed material particle size and the amount of steam

The GoBiGas plant, which comprises a 32-MWth dual fluidized bed gasifier, was constructed as a demonstration unit for converting biomass to biomethane via gasification. On several occasions during the commissioning of the plant, low activity of the olivine bed generated a high content of tar in the produced gas, which was deleterious to the downstream equipment. The problem was attributed to a deficiency of ash constituents, and the solution was to control activation of the bed material through the addition of K2CO3 to the process. This enabled extended operational periods without tar-related issues. The achieved activity could be lost during interrupted operation at which time the activation procedure had to be repeated. In the present paper analysis of the bed material samples extracted upon activation and after loss of activity using Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDS) showed similar morphologies for the ash layers formed around the olivine particles. The observed differences mainly related to the distributions of potassium (K) across the layers. Furthermore, surface analysis showed differences in K speciation within the outer regions. K solubility tests and X-ray photoelectron spectroscopy analyses indicated that K was present as an oxide/hydroxide rather than as a silicate on the surface of the active olivine. The presented results are of major relevance for the operation of dual fluidized bed gasifiers with fuels that are potassium-lean when ash components need to be supplied as additives

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Potassium Speciation and Distribution for the K2CO3 Additive-Induced Activation/Deactivation of Olivine During Gasification of Woody Biomass

10.26434/chemrxiv.8021102.v1 ◽

2019 ◽

Author(s):

Pavleta Knutsson ◽

Jelena Maric ◽

Jesper Knutsson ◽

Anton Larsson ◽

Claes Breitholtz ◽

...

Keyword(s):

Fluidized Bed ◽

Photoelectron Spectroscopy ◽

Paper Analysis ◽

X Ray ◽

Activation Procedure ◽

Dual Fluidized Bed ◽

Fluidized Bed Gasifier ◽

Bed Material ◽

Control Activation ◽

Low Activity

The GoBiGas plant, which comprises a 32-MWth dual fluidized bed gasifier, was constructed as a demonstration unit for converting biomass to biomethane via gasification. On several occasions during the commissioning of the plant, low activity of the olivine bed generated a high content of tar in the produced gas, which was deleterious to the downstream equipment. The problem was attributed to a deficiency of ash constituents, and the solution was to control activation of the bed material through the addition of K2CO3 to the process. This enabled extended operational periods without tar-related issues. The achieved activity could be lost during interrupted operation at which time the activation procedure had to be repeated. In the present paper analysis of the bed material samples extracted upon activation and after loss of activity using Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDS) showed similar morphologies for the ash layers formed around the olivine particles. The observed differences mainly related to the distributions of potassium (K) across the layers. Furthermore, surface analysis showed differences in K speciation within the outer regions. K solubility tests and X-ray photoelectron spectroscopy analyses indicated that K was present as an oxide/hydroxide rather than as a silicate on the surface of the active olivine. The presented results are of major relevance for the operation of dual fluidized bed gasifiers with fuels that are potassium-lean when ash components need to be supplied as additives

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The positive effects of bed material coating on tar reduction in a dual fluidized bed gasifier

Fuel ◽

10.1016/j.fuel.2011.10.066 ◽

2012 ◽

Vol 95 ◽

pp. 553-562 ◽

Cited By ~ 111

Author(s):

Friedrich Kirnbauer ◽

Veronika Wilk ◽

Hannes Kitzler ◽

Stefan Kern ◽

Hermann Hofbauer

Keyword(s):

Fluidized Bed ◽

Positive Effects ◽

Dual Fluidized Bed ◽

Tar Reduction ◽

Fluidized Bed Gasifier ◽

Bed Material

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Numerical study of fluid dynamics and heat transfer property of dual fluidized bed gasifier

Energy ◽

10.1016/j.energy.2021.121246 ◽

2021 ◽

pp. 121246

Author(s):

Feihu Fan ◽

Min Zheng ◽

Shiliang Yang ◽

Hua Wang

Keyword(s):

Heat Transfer ◽

Fluid Dynamics ◽

Fluidized Bed ◽

Numerical Study ◽

Transfer Property ◽

Heat Transfer Property ◽

Dual Fluidized Bed ◽

Fluidized Bed Gasifier

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Parametric Study on the Adjustability of the Syngas Composition by Sorption-Enhanced Gasification in a Dual-Fluidized Bed Pilot Plant

Energies ◽

10.3390/en14020399 ◽

2021 ◽

Vol 14 (2) ◽

pp. 399

Author(s):

Selina Hafner ◽

Max Schmid ◽

Günter Scheffknecht

Keyword(s):

Fluidized Bed ◽

Ghg Emissions ◽

Space Velocity ◽

Synthesis Process ◽

Wood Pellets ◽

High Hydrogen ◽

Syngas Production ◽

Dual Fluidized Bed ◽

Bed Material ◽

Gasification Temperature

Finding a way for mitigating climate change is one of the main challenges of our generation. Sorption-enhanced gasification (SEG) is a process by which syngas as an important intermediate for the synthesis of e.g., dimethyl ether (DME), bio-synthetic natural gas (SNG) and Fischer–Tropsch (FT) products or hydrogen can be produced by using biomass as feedstock. It can, therefore, contribute to a replacement for fossil fuels to reduce greenhouse gas (GHG) emissions. SEG is an indirect gasification process that is operated in a dual-fluidized bed (DFB) reactor. By the use of a CO2-active sorbent as bed material, CO2 that is produced during gasification is directly captured. The resulting enhancement of the water–gas shift reaction enables the production of a syngas with high hydrogen content and adjustable H2/CO/CO2-ratio. Tests were conducted in a 200 kW DFB pilot-scale facility under industrially relevant conditions to analyze the influence of gasification temperature, steam to carbon (S/C) ratio and weight hourly space velocity (WHSV) on the syngas production, using wood pellets as feedstock and limestone as bed material. Results revealed a strong dependency of the syngas composition on the gasification temperature in terms of permanent gases, light hydrocarbons and tars. Also, S/C ratio and WHSV are parameters that can contribute to adjusting the syngas properties in such a way that it is optimized for a specific downstream synthesis process.

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