ENVIRONMENTAL PERFORMANCE OF OXYGEN-BLOWN ENTRAINED-BED COAL-GASIFICATION PILOT-PLANT

The behavior of trace elements in four coals during entrained-bed coal gasification in a 50t/d plant (HYCOL) was characterised by their dist ribution in solid, water and gas. More volatile elements were present in dust from water scrubbing (cake) than in slag from the gasifier. Th e cake contained submicron particles. Results from leaching tests on s lag and cake showed that water emissions were below the regulatory lim it. More than 90% of the coal sulfur was liberated and converted to H2 S and COS in the syngas and a few percent of the coal nitrogen convert ed to NH3 and HCN. Since almost all NH3 and HCN can be removed by wate r scrubbing, their contents in syngas were less than a few ppm. The sc rubbing system will remove a significant proportion of submicron parti cles and nitrogen compounds from syngas. The trace elements in syngas and the elements possibly accumulated in the plant devices must be mea sured directly to understand the behavior more precisely.