Deposit build-up and ash behavior in dual fluid bed steam gasification of logging residues in an industrial power plant

Abstract

A promising way to substitute fossil fuels for production of electricity, heat, fuels for transportation and synthetic chemicals is biomass steam gasification in a dual fluidized bed (DFB). Using lower-cost feedstock, such as logging residues, instead of stemwood, improves the economic operation. In Senden, near Ulm in Germany, the first plant using logging residues is successfully operated by Stadtwerke Ulm. The major difficulties are slagging and deposit build-up. This paper characterizes inorganic components of ash forming matter and draws conclusions regarding mechanisms of deposit build-up. Olivine is used as bed

Influence of coated olivine on the conversion of intermediate products from decomposition of biomass tars during gasification

“…A detailed description of the feedstock was provided in a previous work [30]. Figure 2 shows the flow sheet of the DFB gasification process as it occurs in the power plant in Senden, Germany.…”

“…Interactions between ash components and the bed material have different consequences. The formation of layers on bed particles can result in agglomeration, slagging, and deposit buildup [25,[28][29][30][31][32]. However, calcium-rich layers have shown a significant increase of the catalytic activity of bed particles [33][34][35][36] and are therefore highly desirable for gasification processes.…”

Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass

“…The most widely used biomass in energy conversion processes is forest-derived but increasing demand increases its stock prices [1,2] and leads to the necessity to research alternative bio-based fuels. Logging residues are cheaper wood-based alternatives [3], which could be able to substitute parts or the entire logging wood used in biomass-fueled plants for heat and power production. Agricultural waste is a source of biomass that increasingly gains attention, as well as waste streams like sewage sludge and municipal waste, which behave differently to woody-based biomass and therefore need more caution when used in thermochemical energy conversion processes.…”

“…Several studies have shown an interaction between the bed material used in fluidized beds and ash contained in fuel. This interaction can lead to agglomerations [4,[6][7][8], deposits [3,9] and layer formation [10][11][12][13][14][15] on bed material particles. The different mechanisms dominating the particle layer formation on quartz were summarized by Brus et al [8].…”

Investigation of the Formation of Coherent Ash Residues during Fluidized Bed Gasification of Wheat Straw Lignin

“…However, the ash-forming matter in agricultural wastes is different in comparison to woody biomass and causes severe problems in operation, such as deposit build-up [4], slagging and bed agglomeration [5][6][7][8][9]. The latter is particularly important, since bed agglomeration may lead to total bed defluidization and as a consequence, termination of operation.…”