Design Of Crude Distillation Plants With Vacuum Units-Targeting I(Ji-Bagajewicz)-02
The heating utility for a whole conventional plantprocessing a heavy crude is 51.35 MW. The heatdemand-supply diagram and the operation variablesfor a scheme with three pump-around circuits are shownin Figure 9. The pinch point is at 256.5 °C/234.3 °C.Compared with the conventional design without vacuumdistillation,7 the heat deficit within the low to mediumtemperature range is improved but still prevails. Theheat surplus in the PA2 region can be used to cover theheat deficit in the condenser region. Similarly to theatmospheric design, the total energy consumption is notsensitive to the atmospheric tower heat distribution.This enables added flexibility for the heat exchangernetwork design.ConclusionsRigorous targeting procedures have been performedfor three types of complete crude distillation plants. Itwas found that the introduction of a vacuum towerchanges the topologies for both the conventional designand the preflash design, thereby changing the heatdistribution among the many pump-around circuits. In thestripping-type design, however, the heat provided by thevacuum products can’t be utilized. The energy con-sumption for the preflash vacuum design is slightlysmaller than the conventional vacuum design, andtherefore, these two might be considered equivalent.A target for the conventional vacuum design with theheavy crude reveals that there remains to be a large heat deficitin the atmospheric condenser region and the totalenergy consumption will not be sensitive to the atmospherictower heat distribution. The energy targets obtainedabove are used partially II of this work12 to develop a heatexchanger network for a complete distillation plant.AppendixThe properties of the crude oils used are summarizedin Table A.1. The method rate is 5000 bbl/h. The TBPdata and light ends composition are given in petroleum equipment sales 2017 Tables A.2and A.3, respectively.Literature Cited(1) Nelson, W. L. Petroleum Refinery Engineering, 4th ed.;McGraw-Hill: New York, 1958.(2) Packie, J. W. Distillation Equipment in the Oil RefiningIndustry. AIChE Trans. 1941, 37, 51.(3) Watkins, R. N. Petroleum Refinery Distillation; Gulf Pub-lishing Co.: Houston, TX, 1979.(4) Liebmann, K.; Dhole, V.; Jobson, M. Integration Design ofa Conventional Crude Oil Distillation Tower Using Pinch Analysis.Inst. Chem. Eng. A 1998, 76, 335.(5) Sharma, R.; Jindal, A.; Mandawala, D.; Jana, S. Design/Retrofit Targets of Pump-Around Reflexes for Better EnergyIntegration of a Crude Distillation Column. Ind. Eng. Chem. Res.1999, 38, 2411.(6) Bagajewicz, M. On the Design Flexibility of AtmosphericCrude Fractionation Units. Chem. Eng. Commun. 1998, 166, 111.(7) Bagajewicz, M.; Ji, S. Rigorous Procedure for the Design ofConventional Atmospheric Crude Fractionation Units. 1. Target-ing. Ind. Eng. Chem. Res. 2001, 40, 617.(8) Bagajewicz, M.; Soto, J. Rigorous Procedure for the Designof Conventional Atmospheric Crude Fractionation Units. 2. HeatExchanger Networks. Ind. Eng. Chem. Res. 2001, 40, 627.(9) Ji, S.; Bagajewicz, M. Design of Crude Fractionation Unitswith Preflashing or Prefractionation: Energy Targeting. Ind. Eng.Chem. Res. 2002, 41, 3003.(10) Ji, S.; Bagajewicz, M. On the Energy Efficiency of Strip-ping-Type Crude Distillation. Ind. Eng. Chem. Res. in press.(11) Bagajewicz, M.; Soto, J. Rigorous Procedure for the Designof Conventional Atmospheric Crude Fractionation Units. 3. Trade-Off between Complexity and Energy Savings. Ind. Eng. Chem.Res. manuscript submitted.(12) Ji, S.; Bagajewicz, M. Design of Crude Distillation Plantswith Vacuum Units. II. Heat Exchanger Network Design. Ind.Eng. Chem. Res. 2002, 41, 6100-6106.(13) Liebmann, K. Integrated Crude Oil Distillation Design.Ph.D. Dissertation, University of Manchester Institute of Science& Technology, Manchester, U.K. 1996.Received for review December 30, 2001Revised manuscript received August 28, 2002Accepted August 28, 2002IE011040UFigure 9. Conventional vacuum crude distillation (heavy crude).VPA, vacuum pump-around; SW, saline water; Cond, condenserof the atmospheric tower.Table A.1. Feedstock Used for the Designcrude density (kg/m3) throughput (m3/h)light crude 845 (36.0 API) 795heavy crude 934 (20.0 API) 795Table A.2. TBP Data (°C)vol % light crude heavy crude5 45 13310 82 23730 186 34450 281 48270 382 64090 552 N/ATable A.3. Light-Ends Composition of Crudecompound light crude (vol %) heavy crude (vol %)propane 0.78 0.04isobutane 0.49 0.04n-butane 1.36 0.11isopentane 1.05 0.14n-pentane 1.30 0.16total petroleum equipment sales 2017 5.11 0.48Ind. Eng. Chem. Res. Vol.