无烟煤化学链燃烧过程燃料氮转化释放特性

基于赤铁矿石载氧体,在小型单流化床反应器上,开展煤挥发分和焦炭的化学链燃烧研究,探讨挥发分氮和焦氮在化学链燃烧过程中的转化特性。研究表明:燃料氮释放的中间产物HCN和NH₃与铁矿石载氧体具有较高的化学反应亲和性,易于被载氧体氧化生成N₂和NO。淮北无烟煤挥发分氮转化过程中,NO是唯一的氮氧化物,反应器出口中间产物NH₃的释放份额略高于HCN。在煤焦化学链燃烧还原过程中,部分燃料氮释放的中间产物HCN和NH₃被铁矿石氧化导致少量NO的生成,还原过程中无N₂O的释放;较高的还原反应温度加速了NO的生成。减少进入载氧体氧化再生过程的焦炭量可减少空气反应器NO和N₂O的生成。

Fuel nitrogen transfer in chemical looping combustion of anthracite

The present paper presents the investigation of fuel nitrogen transfer of anthracite in chemical looping combustion (CLC) with an iron ore oxygen carrier based on a small scale fluidized bed reactor. With respect to its volatile nitrogen and char nitrogen conversion behavior, the combustion characteristics of volatile matter and its corresponding char were experimentally investigated. The nitrogen intermediates (HCN and NH₃) from fuel nitrogen had a high chemical affinity with the bed materials of the iron ore oxygen carrier towards formation of N₂ and NO. During the volatile nitrogen conversion of the Huaibei anthracite, NO was the sole product of nitrogen oxide. Meanwhile, some HCN and NH₃ were released and the NH₃ concentration was higher than HCN. In the reduction process of char combustion, part of NO was formed due to the oxidation of HCN and NH₃ by the iron ore, and there was no N₂O formation in the process. A high reduction temperature accelerated formation of NO. To reduce the amount of char into the oxidation process, that is oxygen carrier regeneration process, could totally reduce evolution of NO and N₂O in the air reactor.