Analysis Of Energy Utilization Of A 1.5Mt/a Hydrocracking Unit

Hydrocracking units now become more important for oil refinery enterprises to produce high added-value products.Because hydrocrackers can change vacuum gas oil(VGO)which has percent of S and N to products like naphtha,jet oil,diesel and so on.Some products also can be the materials of other units which generate more high-value chemicals.There is a hydrocracking unit which is based on the technology of CLG called Single Stage Reaction Sequenced.And its major products are middle distillates.Its by-products,meanwhile,include LPG,light naphtha and heavy naphtha.This unit is built on 12,2007.With the changing of materials and operations,the situation of the unit is far more different with design.As new technologies and mechanics are unceasingly developed,a comprehensive analysis should really be done of the hydrocracking unit.At first,‘energy-use three-link analysis' is used to estimate the unit's energy.Then it is concerned that electricity and fuel offer the most energy for the unit about 83%.And the energy efficiency is higher when the feed flow increases.However when the feed flow reduces,the energy efficiency descends.Then electricity and fuel come the optimized objects that descend the energy consumption of this unit.During the reaching of electricity consumption,it is found that a lot of high pressure hydrogen has to be sent back just for matching the reaction needs.So a new process is designed which add a line between hydrocracking unit and diesel hydrogenation unit.As a result,hydrocracking unit can sent hydrogen to diesel hydrogenation unit,instead of sent back to the hydrogen pipe.It is found that 150-170t/h is the best situation of this new process.If the feed flow is lower the 150t/h or higher than 170t/h,the new process' efficiency will go down.Then a further method is presented.One of the three hydrogen compressors is transformed,so that it can stable operate on any load.And there is no returned hydrogen any more,after the transformation.This upgrade can save 600 KWh electricity a year witch 150 millions throughput,which means 240 millions CNY is saved.The gas of reaction furnace is lead into fractional furnace's air preheater.This change can recycle heat more 1.125 MW than before.And the combined thermal efficiency also rises up to 91.937% from 90.112%.In fact,the reality combined thermal efficiency is even higher than design,which is almost 93%.And if it can stabilize,140 t fuel oil can be saved a year.