This paper is part II in a series of two. Ash behaviour modelling of the gasi®cation of four biomass fuels is compared with pilot-scale experiments carried out in a pressurised ¯uidised bed gasi®er at the Royal Institute of Technology (KTH) and an atmospheric test rig of Termiska Processer AB (TPS). Experiments were provocative with respect to agglomeration of the bed material. Thus, in the experiments, the agglomeration was allowed to happen without any corrective changes in the operation.
Small-scale experiments showed clear de¯uidisation in ®ve cases. Some degree of bed disturbance or agglomeration occurred in seven out of 13 cases. In nine of these cases, agglomerates were also found in the samples analysed with SEM/EDX analyses.
In six out of 13 cases, the thermodynamic multi-phase multi-component equilibrium calculations were in agreement with SEM/EDX analysis, i.e. predicted formation of agglomerates. In two cases, no or small amounts of agglomerates were predicted, nor were these found with SEM/EDX analysis. In two cases out of 13, the modelling predicted some degree of agglomeration while no agglomerates could be detected with SEM/EDX analysis. However, in these cases, agglomerates were found in the pilot-scale experiments.
Thus it is shown that the thermodynamic multi-phase multi-component equilibrium calculations are a useful prediction tool for the formation of agglomerates in (pressurised) ¯uidised bed gasi®cation of biomass fuels thereby enhancing the understanding of the chemistry involved.