裂解炉管的预涂覆抑制结焦方法

摘要

The inner surfaces of cracking furnace tubes with inner diameter of 10 mm and length of 850 mm were precoated on-line in a bench scale pyrolysis unit. The performances of the precoated tubes for coking inhibition were investigated through naphtha steam pyrolysis tests. The results showed that SiO2 could adhere to the inner surfaces of the tubes after precoating with Si,Al,Si/Al and Si/Al/Ca reagents,but Al2O3 could not adhere to the inner surfaces by itself. The contents of Si,Al and Ca on the surfaces were close to 30%(w),10%(w) and 5%(w) respectively after precoating with the Si/Al/Ca reagent. In the pyrolysis tests, the mass of coke deposition on the inner surfaces of precoated tubes was lower than that of un-precoated tube. The mass of coke deposition was decreased by 85% in the fi rst pyrolysis test and was still decreased by more than 80% in the fi fth pyrolysis test after precoating with the Si/Al/Ca reagent. The yields of ethylene,propylene and butadiene in the pyrolysis tests were not aff ected by the precoating.%采用小试裂解评价实验装置对内径为10 mm、长为850 mm的小试炉管进行在线预涂覆，然后以石脑油为裂解原料对预涂覆后炉管的抗结焦能力进行评价。实验结果表明，将有效组分为Si，Al，Si/Al，Si/Al/Ca的预涂覆试剂分别预涂覆后， SiO2能明显在炉管内表面附着，而Al2O3不能单独在炉管内表面附着；当预涂覆Si/Al/Ca混合元素后，Si元素在表面元素的含量约为30%（w）、Al元素含量接近10%（w）、Ca元素含量接近5%（w）。在小试裂解结焦评价实验中，经过预涂覆后炉管的结焦量低于空白炉管，尤其是利用Si/Al/Ca混合元素预涂覆后，第1次裂解实验结焦量减少85%，第5次裂解实验结焦量仍能减少80％以上。炉管预涂覆对乙烯、丙烯和丁二烯收率的影响不明显。