Effect of Inherent Minerals on the Release of Fuel-Nitrogen during Coal Pyrolysis

The formation of NO x precursors (mainly HCN and NH 3 ) from the pyrolysis of Pingshuo coal with or without minerals was studied in a quartz fixed bed reactor. The coal sample in the reactor was heated in two kinds of fashion: at a slow heating rate by temperature-programmed and at a fast heating rate than constant temperature. The experimental results revealed that demineralization by acid washing drastically decreases nitrogen conversion to NH 3 at a fast heating rate and at a slow heating rate, but for HCN, its formation is different at fast heating and slow heating rates. The yield of HCN from demineralized coal is slightly lower than that from raw coal at a fast heating rate and it is the reverse at a slow heating rate. On the other hand, the pyrolysis experiments data of demineralized coal and raw coal added with ash from Pingshuo coal combustion also indicated that minerals in coal play an important role in gaseous-N formation, but the reaction mechanism is different for raw coal and demineralized coal.