Strategy And Implementation Of Upgrading And Reform Of Vacuum Deep Cut

As for the actual application conditions of atmospheric and vacuum distillation units after eliminating bottlenecks in Qingdao petrochemical company,the vacuum deep cut technique in atmospheric and vacuum distillation units was discussed to introduce the technological process in vacuum deep cut devices.The critical factors of vacuum deep cut technique have been specifically analyzed.The effect of vacuum furnace outlet temperature,pressure in the feed part of vacuum tower,and the stripping steam in the vacuum tower bottom,on the distillate yield of vacuum gas oil were investigated emphatically.High outlet temperature in the furnace,high carbon residue,high C₇-insoluble,and high heavy metal?Ni and V?content in the vacuum mixed wax oil,content of would lead to a low residue yield.As the increasing of pressure in the feed part of vacuum tower from 20 mmHg to 35 mmHg,the weigh of mixed wax oil product gradually be lighter,as was the the vacuum residue,while the content of residue above 500 ??D2887?gradually increased from 26.63%to 29.30%.As the increasing of stripping steam form 0 kg/h to 1500 kg/h,the weigh of mixed wax oil product changed little,while the residue above 500 ? decreased from 5.8%to 3.9%.The influences of gas injection in vacuum furnace,wash oil,and the bottom temperature in vacuum tower,on the long cycle of the device were studied.At the operating condition of 1.5 t/h of gas injection content in heating furnace and the wash oil of more than160 t/h,the continuous running of heating furnace and vacuum tower was quite well during three years,since no obvious coke formation was found inside the furnace tube,and the pressure drop across the total tower was steady throughout the production cycle.Under the vacuum pressure,the dew point temperature of water was lower than 15 ?,and the tower temperature was controlled beyond 15 ?,which could be beneficial to avoid the dew point corrosion.The economic benefits before and after eliminating bottlenecks and reforming were compared.Experimental results showed that the vacuum cut temperature less than 565 ? could be obtained at the condition of 3.0?4.0 KPa of pressure in gasification zone and 420?425 ? of vacuum furnace outlet temperature of the branch,by optimizing technological parameters in the atmospheric and vacuum devices based on existing vacuum deep cut technique.After the reformation of eliminating bottlenecks,the ultimate vacuum furnace branch outlet temperature could be controlled around 425 ? by gradually optimization while keeping the gas injection content at 1.5 t/h.With the same wash oil proportion of 190 t/h,the working of vacuum tower was in good condition during the second period of four-year continuous running.As the increasing of stripping steam in vacuum tower bottom from 0kg/h to 1500 kg/h,the weigh of mixed wax oil was hardly changed,while the residue content beyond 500 ? decreased from 2.5%to 1.4%.The lower pressure in feed part was beneficial to the vacuum deep cut,but the pressure in feed part subjected to the vacuum pumping ability of vacuum tower top and the limitation of pressure drop across the total tower.The devices could meet the requirement of safe operation at the vacuum deep cut temperature beyond 565?,on the premise of raw material quality of downstream related units.The vacuum deep cut technique not only provided facilitating conditions for the normal operation of Qingdao petrochemical company,but also exhibited working experience of large-scale devices of vacuum deep cut for other domestic refineries,which produced significant economic and social benefits.