年产20万吨尿素生产工艺设计

哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文#Methanolisoneofthelowmolecularweightalcoholsthoughttoactasanactivatorspeciesintheureaprocess.?Thepreseneeofmethanolisthoughttoincreasethesolubilityofureainthefuel,whichresultsinamorecompleteurea/alkanereactionandfasterreactiontimes.AlsoshowninFigure2istheDSCcurveforfueltreatedwithamixtureofureaandmethanol.Theaboveprocedurewasrepeatedwiththeadditionof1mLofmethanol.Thefigureshowsthattheurea/methanoltreatmenteliminatesthefreezingexothermoutbelow-65°C,providingashiftintheexothermpeakbymorethan10°C.Thisshowsthattheurea/methanoltreatmenthasthepotentialtoproducefuelthathasimprovedlow-temperaturepropertiesbeyondthatofin-specificationJPTS(seeFigure1forcomparison).Toconfirmthattheimprovedlow-temperaturebehaviorisduetotheremovalofnormalalkanes,asexpectedfrompreviousstudies,andtostudytheselectivityoftheprocessforvarioussizealkanes,weusedgaschromatography(GC)tomeasurethechangeinconcentrationofthenormalalkanesuponureatreatment.Figure3showsachromatogramofthe3219fuel,whichshowsthatthisfuelcontainsnormalalkanesprimarilyintherangeCtoC,withonlyverysmallamountsofC(<0.0591617mol%).Figure4showsthepercentdecreaseinconcentrationofthesenormalalkanesaftertheurea/methanoltreatmentdescribedabove.Thesmalleralkanes,CtoC,aredecreasedby10to25%.Thelargernormal913alkanes(>C)areremovedtothegreatestextent,withessentially100%14removalofn-C.Thisshowsthattheurea/methanoltreatmentprocessis16selectivetowardthelargernormalalkanespresentinjetfuel.Thisselectivitytowardlong-chainn-alkanesisquitedesirable,asthesespecieshavebeenimplicatedasbeingthefirstspeciestocrystallizeuponthecoolingofthesefuels.12_1Theinitialcrystallizationofthesespeciescausesfuelclouding,whichatlowertemperaturesand/orlongertimes,resultsinfuelgelationandtheinhibitionoffuelflow.Aprimarybenefitoftheurea哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文adductionprocessisinthisselectivitytowardremovalofthespeciesthatformsolids(relativelylargenormalalkanes),whilebeingmuchlesslikelytoreactwithotherfuelspecies,suchasaromatics,branchedalkanes,andcycloalkanes(naphthenes).Also,theprocesssignificantlylowersthemeasuredfreeze,cloud,andpourpoints(seebelow),whiletheuseofcold-flow-improvingadditiveshasnotdemonstratedsignificantchangesinFigure3Chromatogramoffuel3219showingnormalalkanes.Figure4Plotofpercentdecreaseofvariousnormalalkanesafterurea/methanoltreatment.xcix哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文哈尔滨理工大学学士学位论文附录CCIM.s.密呂.紹s.i.ABlii.tw.u?-w.rBRs.Flic<=■UJ0三E?SIi$SH.-£Eiw^Ei5E*wk=FIeax!*jfKfs!署加.啟宜鬲芒一奁貝川町tb-困醫■l-sprELH泾軌日吏0R134站里UImg曲r^.K.ss—sT7Ayh§org爼庐v蚤巧：.F「<」ITII—o1占1营邕拾240蚩fn.Enthalpy轩二闪一1]V、A\-fvCP崑tetjtug誉酱C