Na基添加剂对梅花井煤快速热解过程中硫元素迁移转化的影响OA

At present,research on the effects of additives on sulfur migration and transformation during coal pyrolysis is mainly focused on slow pyrolysis,whereas studies on rapid pyrolysis are limited.However,rapid pyrolysis demonstrates obvious advantages including faster heating rates,lower probabilities of secondary reactions,and better alignment with practical industrial conditions.To investigate the effects of additives on sulfur migration and transformation during rapid coal pyrolysis,the rapid pyrolysis process was simulated using a free-fall reactor,and different Na-based additives(NaCl,Na2CO3,NaOH)were added by an impregnation method,the impacts of Na-based additives on the migration and transformation of sulfur during the rapid pyrolysis of Meihuajing coal were investigated at different pyrolysis temperatures(500℃‒1 000℃).The results show that at 500℃and 600℃,the addition of NaCl inhibits the release of both H2S and COS,whereas the addition of Na2CO3 promots their release.Interestingly,the addition of NaOH promotes the release of H2S but inhibits the release of COS.At 700℃and 800℃,the addition of NaCl facilitats the release of H2S and COS,while the addition of Na2CO3 and NaOH reduce the release of H2S and COS.At 900℃and 1 000℃,all three Na-based additives inhibit the release of H2S and COS,but their inhibition mechanisms are different.NaCl promotes the capture of sulfur-containing groups by organic matter and fixes sulfur into the char in the form of thiophene.Na2CO3 reacts with sulfur-containing gases to form Na2S and fixes sulfur in the char in the form of inorganic sulfur.NaOH also promotes the capture of sulfur-containing groups by organic matter and fixes sulfur into the char in the form of sulfoxide and thiophene.The sulfur fixation efficiency of the three Na-based additives ranks in descending order:NaOH,Na2CO3,NaCl,with sulfur fixation rates reaching 81.5%,76.3%,and 68.7%at 1 000℃,respectively.