气氛及甲烷催化活化对流化床煤热解的影响

Effect of Atmosphere and Methane Catalytic Activation on Coal Pyrolysis in Fluidized Bed Reactor

为了提高煤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N_2,N_2+H_2,CH_4+N_2,CH_4+H_2等气氛及前置Ni/Al_2O_3催化剂对流化床煤热解的影响,结果表明:H_2气氛会减少半焦产率,增加焦油产率;CH_4气氛在800℃时反而会增加半焦产率,同时高温下CH_4的分解对焦油产率的增加有促进作用,相比于N_2气氛,焦油产率提高了35.8%;CH_4+H_2气氛下半焦焦油产率的总体趋势同H_2气氛下相同.还原性气氛有利于焦油的轻质化:H_2,CH_4+N_2,CH_4+H_2气氛下800℃时,轻质焦油的占比分别较N_2气氛提高了29.1%,15.2%,24%.在CH_4+N_2和CH_4+H_2气氛下,采用前置Ni/Al_2O_3催化剂后,焦油产率都得到不同程度的提升.CH_4+N_2气氛下600℃时,催化剂可以使焦油产率较无催化剂时提高40%;CH_4+H_2气氛下800℃时,催化剂对CH_4的催化效果更好,热解气中CH_4含量明显减少,而焦油产率较无催化剂时提高了37%.Ni/Al_2O_3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.

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;CH4can increase semicoke yield at 800 ℃.Due to the decomposition of methane,compared with N2 atmosphere,CH4can increase tar yield by 35.8%.In CH4＋H2atmosphere,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 at mosphere,light tar ratio increases by 29.1%,15.2%,24%,respectively.The Ni/Al2O3 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 ＋N2atmosphere 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.