采用U型管反应系统,研究了氧浓度、气流速率和气化温度对神木煤气化过程中NO_x及其前驱物的释放规律.研究发现:气化时生成的HCN和NH_3总量比热解时大幅下降,表明O_2的引入抑制了H自由基的可获得性.随着氧浓度的增加,NO的收率先减后增,而NO_2收率几乎没有变化.氧浓度较低时,生成的高浓度CO阻止了挥发分氮向NO的转化.气流速率对含氮气相产物释放影响各不相同.低温气化产物以NO_2和HCN为主,NO_2主要来自进样期挥发分的缓慢氧化,而高温气化产物中的NH_3的生成主要来源于焦炭氮.
The formation and release of NO_x and its precursors are investigated during the gasification of Shenmu coal in O_2/Ar with a U-type reactor,the effects of oxygen concentration,gas flow rate and gasification temperature are examined.Experimental results show that the yields of HCN and NH_3 during gasification are much less than those during pyrolysis.It suggests that the presence of O_2 inhibit the availability of H radical.The yield of NO first decreases,land then increases with increased oxygen concentration,whereas the yield of NO_2 hardly changes.The high concentration of CO restrains the conversion of volatile-N to NO while oxygen concentration is low.The gas flow rate exerts a different effect on the release of different N-containing gas product.NO_2 and HCN are predominant N-containing products at low temperatures,and NO_2 may originate from the gradual oxidation of volatile-N while NH_3 from char-N at high temperatures.
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