Abstract
Crystallization tendency and the state of oxidic slags are important influencing factors for slag viscosity and therefore slag tapping. During the gasification process slag is constantly produced and flows down the gasifier walls until it is intercepted and stored for further treatment or a possible valorisation. The kinds of fuel used for gasification lead to different kinds of slag composition likewise. Slag viscosity is strongly influenced by the composition of the slag and the temperature. However, the process of crystallization represents another major influencing factor. Slag crystallization is also affected by several parameters, whose effects need to be considered in experimental studies. This study investigated the impact of the sample state, the chosen crucible material, and the oxygen partial pressure on the crystallization of a Fe-rich oxidic slag in the confocal laser scanning microscope (CLSM) experiment. Using sample powder may lead to heterogeneous nucleation and crystallization during heating due to heterogeneous melting of the compounds. The selection of crucible material is crucial to prevent alloy formation of Fe-species with Pt-crucibles under reducing atmosphere. Finally, the partial pressure of oxygen influences the crystallization tendency as well as the morphology of the crystallized phases. These parameters impede the reproducibility of results as well as the comparison with results deriving from other experiments like sample quenching. This contribution provides an enhanced understanding of the stated parameter effects on the experimental investigation of oxidic slags using the CLSM setup and yields advice to prevent experimental influence on the results.
Highlights
The energy transition is one of the major tasks for mankind in modern days, as the transition from fossil fuels to renewable energies needs tremendous effort
The influence of sample homogeneity, the crucible material, and the oxygen partial pressure on the crystallization of slag was investigated by confocal laser scanning microscope (CLSM) experiments
The CLSM experiment can give insights on the above, since it provides in situ imaging of the investigated sample
Summary
The energy transition is one of the major tasks for mankind in modern days, as the transition from fossil fuels to renewable energies needs tremendous effort. The demand for bridging technologies is high and the usage of gasification technology serves advantages compared to combustion plants [1, 2]. Gasifiers, such as entrained flow gasifiers, are able to convert different kinds of fuels (coal, biomass, waste) into energy [3]. The operation under partial load conditions gives gasification technology a high relevance by filling gaps in the power grid due to fluctuations of renewable energy production [4, 5]. Slag is produced constantly under reducing conditions. Gasifier slags are used in the construction industry as a concrete additive to enhance
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