Potassium speciation and distribution for the K2CO3 additive-induced activation/deactivation of olivine during gasification of woody biomass
Journal article, 2019

The GoBiGas plant, which comprises a 32-MW th 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 K 2 CO 3 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.

Deactivation

Potassium speciation

Olivine

Gasification

GoBiGas

Activation

Author

Pavleta Knutsson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Jelena Maric

Chalmers, Space, Earth and Environment, Energy Technology

Jesper Knutsson

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Anton Larsson

Chalmers, Space, Earth and Environment, Energy Technology

Claes Breitholtz

Valmet Oyj

Martin Seemann

Chalmers, Space, Earth and Environment, Energy Technology

Applied Energy

0306-2619 (ISSN)

Vol. 248 538-544

Subject Categories

Chemical Process Engineering

Other Chemistry Topics

Bioenergy

DOI

10.1016/j.apenergy.2019.04.150

More information

Latest update

8/30/2019