Title : Effect of bed material on syngas quality: comparison of biomass gasification with different bed materials
Abstract:
The selection of suitable bed materials in fluidized bed gasification (FBG) plays a crucial role in optimizing the process. Ideal bed materials must balance economic feasibility, thermal resistance, and minimal chemical interaction with biomass. However, the chemical interactions between biomass and bed materials at high temperatures are often overlooked. This study investigated the performance of commonly used bed materials (such as olivine, K-feldspar,etc.) in FBG systems with different biomass types. The produced syngas was analyzed for composition (H2, CH4, CO, CO2, O2) and contaminants like volatile organic compounds (VOCs), tars, and heavy metals (HMs).
The interaction between biomass and bed materials significantly influenced the quality of syngas and biochar. Olivine showed high performance with arboreal biomass, while K-feldspar proved effective for both arboreal and herbaceous biomasses. To assess metal contamination, a TGA-DSC setup with a bubbler system was employed, capturing HMs released during gasification. ICP-MS analyses provided insights into HM distribution in syngas and solid residues, highlighting that K-feldspar minimized HM release while maintaining stable performance.
This research underscores the importance of selecting appropriate bed materials in FBG processes to enhance syngas quality, reduce undesirable by-products, and improve the overall sustainability of the conversion system. It has been observed that metals, such as Ni, Cu, Zn, Cd, Sn, Ba and Pb, have higher concentrations in the syngas produced by using olivine as bed material rather than K-feldspar. In particular, heavy metals, such as Pb, Cu, Cd, Ni and Zn, show concentrations of 61.06 mg/Nm3, 15.29 mg/Nm3, 17.97 mg/Nm3, 37.29 mg/Nm3 and 116.39 mg/Nm3, respectively, compared to 23.26 mg/Nm3, 11.82 mg/Nm3,
2.76 mg/Nm3, 24.46 mg/Nm3 and 53.07 mg/Nm3 detected with K-feldspar. Moreover, a more hydrogen- rich syngas is obtained when using K-feldspar instead of olivine.
Audience Take Away Notes:
- The proposed work explores a field which has been little investigated in the field of gasification. In fact, in fluid bed gasification, it is often assumed that the material of the bed is chemically inert, but this is not really the case and the literature on this subject is rather poor. The proposed study is particularly useful for those involved in biomass and bioenergy, both at research and industrial level.
