矿物质对煤焦燃烧过程中NO释放规律的影响

在石英固定床反应器上研究了煤焦燃烧过程中矿物质在不同燃烧条件下对NO释放规律的影响.结果表明：煤中的矿物质对燃料氮转化为NO有显著的影响，其影响与矿物质的组成和燃烧条件有关，碱金属Na、K催化半焦氮的氧化在较低的温度下进行并降低半焦氮对于NO的转化率，而Ca、Fe在低温燃烧条件下增加NO的排放，高温时使NO的排放降低；矿物质惰质组分的存在使NO的排放增加；随着煤阶的升高，半焦的反应性降低，燃料氮对于NO的转化率增大；燃料氮的转化率随燃烧温度的升高而增加，但达到极大值后又趋于降低；矿物质对于NO排放量的影响决定于矿物质对于半焦氮的氧化以及半焦还原NO反应催化作用的相对大小.

EFFECT OF MINERAL MATTER ON RELEASE OF NO DURING COAL CHAR COMBUSTION

Chars prepared from coals treated with concentrated acids of HF and HCl to remove mineral matter were combusted under programmed temperature and isothermal conditions.The results showed that mineral matter in coal char played an important role in the conversion of char-N to NO. Alkali metals Na and K shifted the production of NO from char-N to a lower temperatures and inhibited NO emission. However, Ca and Fe increased the conversion of char-N to NO at a lower temperatures but decreased the release of NO at a higher temperatures, which implied the importance of catalytic condition and the complicated mechanism of NO formation and reduction. It was demonstrated that inert mineral matter in the char enhanced the conversion of char-N to NO. The net effect of mineral matter on NO emission level was combined effect of many components in mineral matter. It was also found that char-N conversion to NO increased with coal rank and NO emission increased with increasing temperature to maximum then decreased at a high temperature. The effect of mineral matter on NO emission depended on its relative catalytic activity in the oxidation of char-N to NO and reduction of NO by char.