气氛及甲烷催化活化对流化床煤热解的影响

摘要

In order to improve the yield and quality of coal tar,the effects of atmosphere and Ni/Al2O3 catalyst on coal pyrolysis characters were investigated in a fluidized bed in H2,CH4,N2 and mixed atmosphere.The results show that H2 can reduce semicoke yield and increase tar yield;CH4 can increase semicoke yield at 800 ％C.Due to the decomposition of methane,compared with N2 atmosphere,CH4 can increase tar yield by 35.8％.In CH4 +H2 atmosphere,semicoke and tar yield have the same trend with H2 atmosphere.Reducing atmosphere is beneficial to improving the quality of the tar.In H2,CH4 +N2,CH4 +H2 atmosphere,light tar ratio increases by 29.1％,15.2％,24％,respectively.The Ni/Al2Os catalyst placed before the reaction segment can improve semicoke and tar yield to different degrees.At 600 ℃,compared with coal pyrolysis in CH4 +N2 atmosphere without catalyst,adding Ni/Al2O3 into CH4 +N2 atmosphere increases tar yield by 40％.In CH4 + H2 atmosphere,the Ni/Al2O3 has better catalytic effect on CH4 at 800 ℃,and CH4 in the pyrolysis gas decreased significantly,meantime tar yield increases by 37％ compared that of without catalyst.Ni/Al2O3 can further improve the quality of the tar and is beneficial to the formation of aromatic compounds.%为了提高燥热解焦油的产率和品质,在小型流化床实验台上分别考察了N2,N2+H2,CH4+N2,CH4+H2等气氛及前置Ni/Al2O3催化剂对流化床煤热解的影响,结果表明:H2气氛会减少半焦产率,增加焦油产率;CH4气氛在800℃时反而会增加半焦产率,同时高温下CH4的分解对焦油产率的增加有促进作用,相比于N2气氛,焦油产率提高了35.8％;CH4+H2气氛下半焦焦油产率的总体趋势同H2气氛下相同,还原性气氛有利于焦油的轻质化:H2,CH4+N2,CH4+H2气氛下800℃时,轻质焦油的占比分别较N2气氛提高了29.1％,15.2％,24％.在CH4+N2和CH4+H2气氛下,采用前置Ni/Al2O3催化剂后,焦油产率都得到不同程度的提升.CH4+N2气氛下600℃时,催化剂可以使焦油产率较无催化剂时提高40％;CH4+H2气氛下800℃时,催化剂对CH4的催化效果更好,热解气中CH4含量明显减少,而焦油产率较无催化剂时提高了37％.Ni/Al2O3催化剂可以进一步提高焦油的品质,并且有利于焦油中芳香烃的生成.