Introduction of Chemical Process Simulator Ph.D. 1 st Week August 20, 2001 through August 26, 2001
? (Chemical Process Simulator) Computer Hardware Software. Henry Cho
Process Simulation Reality Feeds Energy Physical Process Products Mathematics Data Describing Feed Data Describing Energy Mathematics Describing Process Data Describing Products
(Purposes for Simulation?) New Plant Design ( ) Existing Plant Revamp (Expansion) Existing Plant perations Engineer Training
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Advantages of Simulation Faster Calculations - More solutions Accurate Results Standardization - Pure Component / Binary Database - Thermodynamic Methods Solution of Recycle Processes Less Costly than Plant Tests!!
(I) Faster Calculations The equilibrium flash separator is the simplest equilibrium-stage process with which the designer must deal. Despite the fact that only one stage is involved, the calculation of the compositions and the relative amount of the vapor and liquid phases at any given pressure and temperature usually involves a tedious trial-and-error solution. Buford D. Smith, 1963
(II) Standardization Pure Component Database 1,700 Binary Database 10,000 Thermodynamic ption 60 ES Model, LACT Model, Special Package!
(III) Solution of Recycle Process Sequential-Modular Approach 2 6 1 5 3 4 8 7
(IV) Less Costly than Plant Tests! ( 1 5,000 ), ( ). (, ).
New Plant Design When should we use it? Ex) Depropanizer (Dec3) 1. Feasibility Study 2. Case Study 3. Final Heat and Material Balance 4. Equipment Sizing and Rating 1. Product 2. Tower 3. Duty Size 4. Basic and Detail Engineering
Depropanizer New Design (I) Feedstock Characterization No. Component Moles/hr 1 2 3 4 5 6 7 8 C2 C3 ic4 nc4 ic5 nc5 nc6 C7+ Temp. (of) Press. (psia) 225 400 0. 04 23.49 15.02 20.40 7.14 5.62 4.86 3.61
Depropanizer New Design (II) 1. Determine the number of tray to obtain: a) less than 2 mole % of ic4 impurity at overhead b) less than 1.5 mole % of C3 impurity at bottoms 2. Determine the column pressure, based on a condenser outlet temp. of 120 o F. 3. Use SRK method for VLE. 4. A design basis of 1.5 times the min. number of tray is to be assumed.
How we can determine the condenser type? A. Partial B. Bubble or sub-cooled C. Mixed D. Mixed with decanter
It depends on the refrigerant available and feed composition. verhead molar flow rate (assume) C2 = 0.04, C3 = 23.49, ic4 =? (2 %) Normalize! (Component mole %) C2 = 1.69, C3 = 97.83, ic4 = 0.48 Bubble pressure at 129 o F = 282 psia Column top pressure = 287 psia Column pressure drop = 5 psia
Shortcut Model Key components Light key component = C3 Heavy key component = ic4 Minimum No. of tray = 15 Theoretical No. of tray = 15 x 1.5 = 23 Vapor Mole Fraction of C3 BVLE for C3/iC4 at 287psia 1.0.9.8.7.6.5.4.3.2.1 0.0 0.0.1.2.3.4.5.6.7.8.9 1.0 Liquid Mole Fraction of C3
Rigorous Simulation ( I )
CLUMN SUMMARY ---------- NET FLW RATES ----------- HEATER TRAY TEMP PRESS LIQUID VAPR FEED PRDUCT DUTIES DEG F PSIA LB-ML/HR MM BTU/HR ------ ------- -------- -------- -------- --------- --------- ------------ 1C 120.0 282.00 165.4 29.0L -1.1022 2 135.9 287.00 180.7 194.4 4 141.9 287.48 175.4 207.4 5 146.9 287.71 171.8 204.4 8 169.4 288.43 161.3 193.6 9 178.0 288.67 157.2 190.3 10 187.7 288.90 149.2 186.2 11 201.6 289.14 240.6 178.1 100.0M 16 220.7 290.33 249.2 176.2 17 224.3 290.57 251.2 178.2 21 239.0 291.52 251.6 183.1 22 246.5 291.76 242.3 180.6 23R 262.9 292.00 171.3 71.0L 1.1347
Existing Plant Revamping 1. (Debottlenecking) 2. Feed 3. 4. 5. Product 6.
Existing Plant perations 1. 2. 3. Yield 4. Capacity
Crude Distillation Column Q1 Q2 NAPHTHA Q3 STM2 KERSENE Q4 STM3 Q5 DIESEL STM4 GAS IL CRUDE PREHEAT FUMACE STM1 TPPED CRUDE
Crude Distillation Column Q1 Q2 Q3 Q4 Q5 SUM RECVER(%) CASE 1 CASE 2 CASE 3 CASE 4 104 70 70 70 0 26 19 9.6 15 22 20 15 10 10 20 25 0 0 0 10 129.0 128.0 129.0 129.6 19.4% 45.3% 45.7% 46.0% NAPH KER DIES GASIL RESID CASE 1 CASE 2 CASE 3 CASE 4 480 478 478 477 213 217 166 140 322 330 399 427 68 69 37 40 1405 1405 1420 1417 PRDUCT TARGET ASTM D86 (95%) NAPHTHA 300 o F KERSENE 445 o F DIESEL 576 o F GAS IL 690 o F
Case Study Case 1 Case 2 Product Case 2 34MMBTU/HR High Quality Heat( ). Case 3 Case 4, Kerosene Diesel. Case 4. Steam 1 13,000( 99 ) Case 1 15. 60 70% Pumparound Side Cooler 78 91 MM Btu/HR.
Pumparound Cooler verhead Condenser Heat Duty Cold Utility. Furnace Heater Load. Column Vapor Load Column Diameter.
Nonaromatics BTX Lean Solvent Feed T01 T02 T01 : Extractive Distillation Column T02 : Solvent Recovery Column Rich Solvent
Solvent Reformate Benzene Fraction Vapor STRIPPER CLUMN Non-aromatics Vapor EXTRACTIVE DISTILLATIN CLUMN Non-aromatics Benzene Vapor Vent Benzene CLAY TWER Pure Benzene Vapor Pure Benzene STRIPPER CLUMN BENZEN CLUMN Rich Solvent Heavy Fraction Lean Solvent Toluene
Thermophysical properties Method using in the simulation Critical properties[tc, Pc, Zc, etc.] Joback method (molecular structure) Pure vapor pressure of NFM Binary: LLE Peng-Robinson eqution Experimental data and estimation(nrtl binary parameters of component i and j, UNIFAC-LLE model, Dortmund modified UNIFAC model, and Lyngby modified UNIFAC model ) NFM / n-heptane NFM / n-hexane NFM / Cyclopentane NFM / iso-hexane NFM / Methylcyclohexane : VLE Database and UNIFAC model
T P V = T [ 0584. + 0965. ( ) ] c b T T = ( 0113. + 00032. n ) c A P c = 17. 5 + V 2 2 1 By By Peng-Robinson) ω = log P ( at Tr = 07. ) 1000. w Temperature( )Pressure(mbar)
VLE NFM VLE EB VLE TL LLE BEN LLE IC6 LLE ECH LLE MCH LLE CHX LLE CP LLE NC8 LLE NC7 LLE NC6 LLE NC5 NFM EB TL BEN IC6 ECH MCP MC H CHX CP NC8 NC7 NC6 NC5
160 140 120 UCST EXPERIMENTAL DATA Temperature 100 80 A 12 = - 833.59 + 367620 /T A 21 = 569.78-163356 /T UNIQUAC A 12 = -2195.22 + 1053890.33 /T A 21 = 1108.34-210634.86 /T NRTL 60 40 0.0 0.2 0.4 0.6 0.8 1.0 mole fraction x MCH
ED Column VHD Nonaromatics BTMS Rich Solvent Component DESIGN SIM. DESIGN SIM. NC5 0.5 0.5 0.0 0.0 NC6 NC7 4.1 2.3 4.1 2.2 0.0 0.0 0.0 0.0 NC8 0.1 0.0 7.0 7.3 CP CHX 68.3 75.7 68.4 75.7 0.0 0.0 0.0 0.0 MCP 0.8 0.8 0.0 0.0 MCH ECH 11.3 0.0 9.9 0.0 1.5 0.5 2.9 0.5 IC6 0.0 0.0 2.0 0.0 BENZENE 8.6 7.7 13342.0 13343.0 TLUENE EBENZENE 0.2 0.0 0.4 0.0 2392.9 5.0 2392.6 5.0 NFM 0.0 0.0 75626.0 75626.0 FLW (Kg/Hr) 171.9 171.5 91377.1 91377.3 Temperature ( o C) 72.0 72.9 151.0 158.9
Sulfolane 1. UP Licensed Process ( 11 ) 2. 3. 50,000 4. / / 5. S Sulfolane 6. H, L Sulfolane Revamping Study
RICH SLVENT EXTRACTIN SECTIN HYDRCARBN CIRCUIT F THE SULFLANE PRCESS RAFFINATE FEED E S RC EXTRACT T TREATING AND FRACTINATIN RECYCLE LEAN SLVENT LEGEND SR E = EXTRACTR S = STRIPPER RC = RECVERY CLUMN SR = SLVENT REGENERATR
Sulfolane Process Name Extractor Stripper Column Recovery Column bjective Feed, Stripper. Extractor Extract Reboiler Raindeck Extractor Stripper,.
Raindeck Extractor 263 # 1 # 51 111 RAINDECK A-DA-401 EXTRACTR Feed, Stripper. 101 175 # 72 # 83 101 : FEED 111 : RAFFINATE 151 : EXTRACT 175 : STRIPPER CLUMN VHD 263 : LEAN SLVENT FEED 151
Extractor, Rich Case RAFFINATE (111) EXTRACT (151) DESIGN SIMULATIN DESIGN SIMULATIN 1. H2 0.00 0.36 96.55 96.19 2. SULF 2.58 18.44 2395.62 2379.77 3. BZ 0.00 0.00 392.44 392.46 4. TL 0.05 0.00 410.62 410.67 5. M-X 0.00 0.00 3.60 3.61 6. CH 3.86 3.91 3.69 3.64 7. MCH 5.91 6.17 4.10 3.84 8. NC4 0.10 0.10 0.13 0.23 9. NC5 95.70 95.67 91.44 91.47 10. NC6 127.31 130.07 88.36 85.59 11. NC7 29.56 31.31 15.44 13.69 12. NC8 0.00 0.00 0.11 0.11 KML.HR 256.06 285.93 3502.13 3481.28 TEMP ( o C) 93.00 93.00 76.00 76.00 PRES (G) 6.33 6.33 8.79 8.79
Raindeck Extractor 1. Feed 2. Feed 3. Solvent/Feed 4. Major Equipment
Stripper Column 311 156 #1 5.07 STRIPPER CNDENSER A-EA-401 Extractor Extract Reboiler STRIPPER A-DA-403 Raindeck Extractor. 171 #36 190 41 DUTY? STRIPPER REBILER A-EA-404 194
Stripper, Rich Case VDH, 161 H/C, 171 BTMS, 194 DESIGN SIM. DESIGN SIM. DESIGN SIM. H2 63.62 60.79 0.00 1.75 33.49 35.76 SULF 0.92 0.77 0.00 0.77 2394.71 2394.80 BZ 146.31 151.19 146.31 151.19 246.14 241.24 TL 66.49 64.25 66.49 64.25 344.14 346.37 M-X 0.31 0.10 0.31 0.10 3.30 3.50 CH 3.69 3.69 3.69 3.69 0.00 0.00 MCH 4.10 4.10 4.10 4.10 0.00 0.00 NC4 0.13 0.13 0.13 0.13 0.00 0.00 NC5 91.44 91.44 91.44 91.44 0.00 0.00 NC6 88.37 88.36 88.37 88.36 0.00 0.00 NC7 15.44 15.44 15.44 15.44 0.00 0.00 NC8 0.11 0.01 0.11 0.01 0.00 0.00 KML.HR 480.38 480.26 416.40 421.22 3021.77 3021.77 TEMP ( o C) 123.00 125.20 49.00 49.00 174.00 185.00 PRES (G) 1.43 1.43 0.52 0.52 1.85 1.85
Stripper 1. Stripper Column Reboiler Duty (S : 11.8MM Kcal/hr) 2. H Internal Change 140% Load Internal Type Study
Recovery Column RECVERY CLUMN A-DA-404 197 # 1 # 16 201 216 203 RECVERY CLUM CNDENSER A-EC-402 RECVERY CLUMN TRIMCNDENSER A-EA-409 RECVERY CLUMN REBILERS A-EA-405& A-EA-406 253+301 Stripper,. # 20 # 34 204 305 217 226 H, D Upper Reboiler Product spec..
- Sulfolane+benzene+cyclohexane 100 1.45 Mole Percent of Benzene 90 80 70 60 50 40 30 20 10 Distribution Coefficient of Benzene 1.40 1.35 1.30 1.25 1.20 1.15 1.10 0 0 10 20 30 40 50 60 70 80 90 100 Mole Percent of Sulfolane 1.05 5 10 15 20 25 30 35 40 45 50 Mole Percent of Benzene at Bottom Phase
(I) Stripper Column Reboiler Loading Recovery Column Upper Reboiler Sulfolane Utility Feed Major Equipment Solvent / Feed Ratio
(II) Revamping Study ( 3 ) Case Study BTX (14,000 BPD) Benzene : $193 / Ton Toluene : $165 - $170 / Ton Mixed Xylene : $165 - $170 / Ton p-xylene : $400 - $440 / Ton Sulfolane : $4,600 / Ton
Licensor Krupp Koppers GTC UP Type Extractive Distillation Extractive Distillation Extraction Solvent NFM Sulfolane Sulfolane Column 2 2 Extractor = 1 Distil. Column = 5 Solvent / Feed 3.43 3.58 3.97 Ratio (Mass) Aromatics 89.65 % 67.27% (Rich) 70.22% (Rich) wt % in Feed 59.34% (Lean) 65.04% (Lean) Aromatics Recovery % Benzene > 99.5% for verall Plant 99.3 wt% in ED Col. > 99.5 wt% in Extractor / BTX BTX 3 1 11
Binary Data Approach rather than Ternary Data The NRTL parameters obtained (regressed) from the ternary LLE experimental data give a better result than the NRTL parameters obtained from the binary experimental data only. However, the above state holds true when you simulate a system containing only three components in the ternary system. n the other hand, for a system containing components more than ternary system like Sulfolane unit, a better approach should be the binary interaction parameters.
ACN ( NMP, DMF) 1,3 ACN : Nippon-Zeon NMP : BASF DMF : Krupp-Kopper 10 1,3 NMP C4
1,3 C4 Raffinate Butadiene Recycle Solvent Feed 1 st ED Column 1st Stripping Column Flash Drums, Condensers, Compressors Splitters & Pump Raffinate Raffinate Solvent 2nd Extractive Distillation Column 1st Fractionation Column 2nd Fractionation Column Butadiene Product Raffiante Butadiene Recovery Column 2nd Stripping Column Solvent
LLE IC5 SL VLE H2 LLE VAC LLE EAC VLE 12BD LLE MAC VLE 13BD LLE CC4- LLE TC4- LLE IC4- LLE NC4 LLE C3=2 LLE C3 SL H2 IC5 VAC EAC 12BD MA C 13BD CC4- TC4- IC4- NC4 C3=2 C3
- Ethanol-Water System - Using Benzene as an Entrainer - Comparison of two-columns & three-columns configuration - Comparison of Extractive Distillation using Glycol as a Solvent and Azeotropic Distillation using Benzene/NC5 as an Entrainer - Replacing NC5 instead of using Benzene (VC)
Azeotropic and Extractive Distillation Azeotropic Distillation By forming a ternary heterogeneous azeotrope lower than any other binary azeotropic temperatures, nearly pure ethanol can be obtained as a bottom product in an azeotropic distillation column. Ethanol is obtained as a bottom product from an azeotropic distillation column using an entrainer such as benzene or normal pentane. Extractive Distillation By adding a solvent which is exclusively familiar with a wanted component in a feed mixture, a desired component can be obtained in an extractive distillation column overhead. Ethanol is obtained as a top product from an extractive distillation with ethylene glycol solvent.
Azeotropic and Extractive Distillation Azeo. Distil. Extr. Distil.
Fundamental Principle of Alcohol Dehydration using Entrainer Aqueous ethanol can be separated into their pure components by distillation by the addition of a third component, so called the entrainer, which forms a ternary heterogeneous azeotrope with a lower than any other binary azeotropes. Ex) A : Ethanol, B : Water, C : Benzene A-B = 78.07 o C A-C = 69.77 o C B-C = 69.31 o C A-B-C = 63.88 o C
Understanding of Phase Diagram (I) Ethanol 1.0.9.8 P II A F A : 78.07 o C C : 69.31 o C B : 67.99 o C D : 63.88 o C.7.6.5 B.4.3 G V R D W.2.1 0.0 0.0.1.2.3.4.5.6.7.8.9 1.0 Benzene I III C Water nly mixtures in region II will give the desired products of pure ethanol as a bottom product.
Understanding of Phase Diagram (II) 1.0 Ethanol P.9.8.7.6 B A F II III G A : 78.07 o C B : 75.08 o C C : 73.44 o C D : 69.94 o C.5.4.3.2 I R V D W.1 0.0 Ether 0.0.1.2.3.4.5.6.7.8.9 1.0 C Water In this case, pure ethanol cannot be obtained since G is in region III.
Three-columns Configuration in Ethanol Dehydration Recycle stream Feed Concentrated ethanol Upper phase Lower phase Concentrator Azeo Column Stripper Waste water Pure ethanol Waste water
Two-columns Configuration in Ethanol Dehydration Recycle stream Feed Concentrated ethanol Concentror (Dryer) Azeo Column Waste water Pure ethanol
Performance Comparison between Benzene & NC5 as an Entrainer Benzene NC5 Stripping Column Top Press. 1.38 Kg/cm 2 3.5 Kg/cm 2 Theo. Trays 25 25 Entrainer RRATI Theo. Trays Benzene 651 Kgmol/hr 25 NC5 439 Kgmol/hr 25 Reboiler Heat Duty Condenser Heat Duties 2.2512x10 6 Kcal/hr 2.0437x10 6 Kcal/hr 0.1543x10 6 Kcal/hr 0.1369x10 6 Kcal/hr Feed Tray Reboiler Heat Duty Condenser Heat Duty 5 5.2268x10 6 Kcal/hr 3.3290x10 6 Kcal/hr 5 2.6964x10 6 Kcal/hr 2.8552x10 6 Kcal/hr Total Reboiler Duties Total Condenser Duties 7.7580x10 6 Kcal/hr 5.3727x10 6 Kcal/hr 0.1369x10 6 Kcal/hr 2.9912x10 6 Kcal/hr Column 1600 mm 120 mm Diameter (valve tray) (valve tray) Impurities Water : 16ppm Water < 3ppm Benz. : 12ppm NC5 < 1ppm Ethanol 99.99 mole % > 99.99 mole% Recovery
Conclusions Although the azeotropic distillation scheme, using NC5, operates at a higher pressure, comparative calculation results through this study show that azeotropic distillation using NC5 as an entrainer is better than that using benzene as an entrainer.