Simulation And Optimization Study Of Gas Oil Hydrocracking Unit

In this paper,a running hydrocracking unit in a Chinese refinery was taken as the research object.Firstly,its materials,products,process flow etc.were introduced.According to calibration data,the model of whole unit was built using HCR-SIM module of KBC's Petro-SIM process simulation software,including both the reaction system and separation system.The simulation results were compared with the calibration values,the error was in reasonable range.So the model could reflect actual production status,it was reliable for the subsequent analysis and optimization.The effects of reaction temperature,reaction pressure,LHSV,fractionator operating conditions etc.on product distribution,product quality,energy consumption etc.were analyzed with the HCR-SIM model.Then,in order to increase yields of naphtha,aviation kerosene and diesel,we built and solved 2 optimization problems.The results could be used to instruct actual unit operation.In energy system analysis,the three-link model was used firstly.The 3 links: energy input and conversion,energy using,energy recovery,were all calculated.The results showed that the total energy consumption of this hydrocracking unit was 3630.87 MJ/t,the energy input and conversion efficiency was 85.08%,the energy recovery efficiency was 54.73%.The optimization direction was found and some energy-saving measures were suggested.Then the heat exchanger network of this hydrocracking unit was analyzed using pinch technology,and some unreasonable heat transfers were found.Basing on the results of pinch analysis,two heat exchanger network optimization schemes were suggested.The new added and changed heat exchangers were designed and rated using HTRI software.The comparison results showed that scheme 2 was better than scheme 1.In scheme 2,6.39% of cold utilities and 20.13% of hot utilities could be saved.At last,low temperature waste heat of this unit was suggested to be recovered by power generation,and the calculated generating capacity was 3.5MW,economic benefit was substantial.