某重油催化裂化装置低负荷工况油浆回炼影响分析

Analysis on the influence of slurry recycling with low processing capacity in a heavy oil catalytic cracking unit

某炼油厂2.80 Mt/a重油催化裂化装置在低负荷情况下进行了为期约6个月的油浆回炼,回炼方式是将循环油浆在原料自保组立处打入混合原料油中,再进入原料油喷嘴。标定结果表明:焦炭收率由7.86%升至8.41%,占比约20%的回炼油浆生成了焦炭;装置柴油收率提高,占比约50%的回炼油浆转化成高附加值产品柴油;油浆回炼导致装置总转化率下降,干气、液化石油气、汽油收率共降低1.93百分点。油浆回炼过程中,对原料油及反应系统进行了监控,未发现其对反应系统结焦、烟气轮机运行、原料油管线及原料喷嘴磨损等有明显影响,后续消缺过程中对反应-再生系统内部检查也未发现异常。总体来看,该重油催化裂化装置进行油浆回炼可以提高装置焦炭收率,保证低负荷下全厂蒸汽平衡,可显著降低油浆固含量,有助于降低装置油浆收率。

A 2.8 MM TPY heavy oil catalytic cracking unit in a refinery has been undergoing slurry recycling for about six months under low processing capacity.The recycling method involves injecting the recycled slurry into the mixed feedstock oil at the feedstock self-protection assembly and then into the feedstock oil nozzle.After calibration,the yield of coke increases from 7.86%to 8.41%,accounting for about 20%of the recycled slurry to produce coke.The diesel yield of the unit has increased,and about 50%of the recycled slurry has been converted or becomes high-value diesel products.The slurry recycling resulted in a decrease in the overall conversion rate of the unit,with a total reduction of 1.93 percentage points in the yields of dry gas,liquefied petroleum gas,and gasoline.During the recycling process of slurry,the unit monitors the feedstock oil and reaction system,and has not found any significant impact on coking in the reaction system,wear of the feedstock oil pipeline and nozzle,or other defects.Subsequent defect elimination inspections have also not found any abnormalities.Overall,the recycling of slurry increases the coke yield of the unit,ensures steam balance in the entire plant under low processing capacity,and effectively reduces the solid content of slurry,resulting in a decrease in the yield of slurry in the unit.