Modelling, comparison and operation experiences of entrained flow gasifier

In this paper a generic entrained flow gasifier is modelled in Aspen Plus using different designs e.g. wet/dry feed as well as wet and dry quench. The models are verified with the corresponding data from real existing plants or reference data from the literature. All of them are found to reproduce the raw gas composition as well as synthesis gas yield with acceptable deviation. The comparison of the selected designs revealed the poor performance of the wet feed compared to the dry design. The corresponding cold gas efficiency of 72.1% is much lower than the 83% for the dry feed cases. Furthermore the specific synthesis gas production is 12% lower at 12% higher oxygen demand. On the other hand, the power demand for the gasification island is found to be 60-70% lower than in the dry feed case. Therefore the wet feed design is recommended only in case of high pressure gasification. During, an exergy analysis of the different raw gas cooling concepts the disadvantage of the direct quench became obvious. Combinations of gas quench and heat recovery results in exergy losses of 52.4%. The heat recovery design showed much better exergy efficiency of 63.8%. Especially the wet quench design showed high looses and is therefore restricted to applications incorporating a down stream shift unit.