7 Các thao tác thường dùng trong mơ phỏng bằng PRO/II
8.6 Bài tốn 6: Xác định số đĩa lý thuyết tối thiểu và chỉ số hồi lưu tối thiểu cho
hồi lưu tối thiểu cho tháp tách propane bằng phương pháp shortcut
8.6.1 Bài tốn
Tính cho tháp Depropanizer với các dữ liệu ban đầu như sau :
• Nguyên liệu :
- năng suất : 400 tấn/ngày - P = 18 bar
- cĩ thành phần 40% hơi gồm : 26% khối lượng propane và 74 % khối lượng butane
• Tháp :
- áp suất đỉnh : 16,5 bar
- thiết bị ngưng tụ hồn tồn - áp suất bình tách : 16,2 bar
• Chỉ tiêu chất lượng sau :
- sản phẩm đỉnh : cĩ 0,5% khối lượng C4 - sản phẩm đáy : cĩ 0,5% khối lượng C3
⇒ Hãy xác định :
- Số đĩa lý thuyết tối thiểu? - Chỉ số hồi lưu tối thiểu?
8.6.2 Tiến hành mơ phỏng và xem kết quả
$ Generated by PRO/II Keyword Generation System <version 7.0> $ Generated on: Mon Aug 15 18:33:48 2005
TITLE
DIMENSION METRIC, PRES=BAR, TIME=DAY, STDTEMP=0, STDPRES=1.01325 SEQUENCE SIMSCI
CALCULATION RVPBASIS=APIN, TVP=37.778 COMPONENT DATA
LIBID 1,PROPANE/2,BUTANE, BANK=PROCESS,SIMSCI THERMODYNAMIC DATA
METHOD SYSTEM=GS, SET=GS01, DEFAULT STREAM DATA
PROPERTY STREAM=S1, PRESSURE=18, PHASE=M, LFRACTION(WT)=0.6, & RATE(WT)=400000, COMPOSITION(M)=1,26/2,74
UNIT OPERATIONS SHORTCUT UID=SCD1 FEED S1
PRODUCT STREAM=S2, RATE(WT)=1E5, PHASE=L, PRESSURE=16.2 PRODUCT STREAM=S3, PHASE=L, DP=0
CONDENSER TYPE=BUBB
EVALUATE MODEL=CONV, TRIAL=50, KEYLIGHT=1, KEYHEAVY=2, RRMIN=2 FINDEX 2
SPEC STREAM=S2,PCT(WT), COMP=2,WET, VALUE=0.5 SPEC STREAM=S3,PCT(WT), COMP=1,WET, VALUE=0.5 END
SIMULATION SCIENCES INC. R PAGE H-1 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM CALCULATION HISTORY 08/15/05
==============================================================================
*** PROBLEM SOLUTION BEGINS FEED FLASH COMPLETE UNIT 1 SOLVED - 'SCD1 ' *** PROBLEM SOLUTION REACHED
*** THIS RUN USED 20.71 PRO/II SIMULATION UNITS
*** RUN STATISTICS
STARTED 18:33:32 08/15/05 NO ERRORS FINISHED 18:33:33 08/15/05 NO WARNINGS RUN TIMES NO MESSAGES INTERACTIVE 0 MIN, 0.00 SEC
CALCULATIONS 0 MIN, 0.12 SEC TOTAL 0 MIN, 0.12 SEC
SIMULATION SCIENCES INC. R PAGE I-1 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM OUTPUT INDEX 08/15/05 ============================================================================== PAGE CONTENTS --- --- 1 COMPONENT DATA
2 CALCULATION SEQUENCE AND RECYCLES SHORTCUT COLUMN SUMMARY
3 UNIT 1, 'SCD1'
4 STREAM MOLAR COMPONENT RATES 5 STREAM SUMMARY
SIMULATION SCIENCES INC. R PAGE P-1 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM OUTPUT
COMPONENT DATA 08/15/05
==============================================================================
COMPONENT COMP. TYPE PHASE MOL. WEIGHT DENSITY KG/M3 --- --- --- --- --- 1 PROPANE LIBRARY VAP/LIQ 44.097 507.199 2 BUTANE LIBRARY VAP/LIQ 58.124 583.824
COMPONENT NBP CRIT. TEMP. CRIT. PRES. CRIT. VOLM. C C BAR M3/KG-MOL --- --- --- --- --- 1 PROPANE -42.070 96.670 42.496 0.2030 2 BUTANE -0.500 152.000 37.997 0.2550
COMPONENT ACEN. FACT. HEAT FORM. G FORM. KCAL/KG-MOL KCAL/KG-MOL --- --- --- ---
1 PROPANE 0.15290 -24805.58 -5633.13 2 BUTANE 0.20130 -30040.13 -3982.90
SIMULATION SCIENCES INC. R PAGE P-2 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM OUTPUT
CALCULATION SEQUENCE AND RECYCLES 08/15/05
==============================================================================
CALCULATION SEQUENCE
SEQ UNIT ID UNIT TYPE --- --- ---
SIMULATION SCIENCES INC. R PAGE P-3 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM OUTPUT
SHORTCUT COLUMN SUMMARY 08/15/05
============================================================================== UNIT 1, 'SCD1' FEEDS STREAM PHASE --- --- S1 MIXED PRODUCTS
--- TOTAL STREAM RATES ---
MOLES WEIGHT LIQUID VOL NORM VAPOR(1) NUM STREAM + PHASE KG-MOL/DAY KG/DAY M3/DAY M3/DAY SECTION TRAYS --- --- - --- --- --- --- --- --- S2 L 1880.26 83014.05 163.56 42144.15 1 13.60 S3 L 5462.28 316985.62 543.36 122431.59 TOTALS 7342.54 399999.66 706.92 164575.74 13.60 SPECIFICATIONS
PARAMETER COMP. SPECIFICATION SPECIFIED CALCULATED TYPE NUM TYPE VALUE VALUE --- --- --- --- ---
STRM S2 2 WT PERCENT 5.000E-01 5.001E-01 STRM S3 1 WT PERCENT 5.000E-01 5.000E-01
SUMMARY OF UNDERWOOD CALCULATIONS
MINIMUM REFLUX RATIO 3.95841 FEED CONDITION Q 0.59108 FENSKE MINIMUM TRAYS 13.60067
OPERATING REFLUX RATIO 2.00 * R-MINIMUM
TOTAL FEED R/R-MIN M/M-MIN REFLUX DUTY, M*KCAL/DAY TRAYS TRAY RATIO CONDENSER REBOILER --- ---- --- --- --- --- --- 23 15 1.500 1.657 5.938 -3.924E+01 2.891E+01 21 14 1.750 1.526 6.927 -4.484E+01 3.450E+01 20 13 2.000 1.437 7.917 -5.044E+01 4.010E+01 19 12 2.250 1.372 8.906 -5.604E+01 4.570E+01 18 12 2.500 1.323 9.896 -6.164E+01 5.130E+01 (1) NORMAL VAPOR VOLUME IS 22.414 M3/KG-MOLE (0 C AND 1 ATM)
SIMULATION SCIENCES INC. R PAGE P-4 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM OUTPUT
STREAM MOLAR COMPONENT RATES 08/15/05
==============================================================================
STREAM ID S1 S2 S3 NAME
PHASE MIXED LIQUID LIQUID
FLUID RATES, KG-MOL/DAY
1 PROPANE 1909.0616 1873.1184 35.9433 2 BUTANE 5433.4831 7.1424 5426.3407
TOTAL RATE, KG-MOL/DAY 7342.5447 1880.2608 5462.2839
TEMPERATURE, C 92.8478 47.4612 101.2441 PRESSURE, BAR 18.0000 16.2000 16.2000 ENTHALPY, M*KCAL/DAY 33.5076 2.6303 20.5389 MOLECULAR WEIGHT 54.4770 44.1503 58.0317 MOLE FRAC VAPOR 0.4089 0.0000 0.0000 MOLE FRAC LIQUID 0.5911 1.0000 1.0000
SIMULATION SCIENCES INC. R PAGE P-5 PROJECT PRO/II VERSION 7.0 ELEC V6.6 PROBLEM OUTPUT
STREAM SUMMARY 08/15/05
============================================================================== STREAM ID S1 S2 S3
NAME
PHASE MIXED LIQUID LIQUID --- TOTAL STREAM ---
RATE, KG-MOL/DAY 7342.545 1880.261 5462.284 K*KG/DAY 400.000 83.014 316.986 STD LIQ RATE, M3/DAY 706.922 163.564 543.358 TEMPERATURE, C 92.848 47.461 101.244 PRESSURE, BAR 18.000 16.200 16.200 MOLECULAR WEIGHT 54.477 44.150 58.032 ENTHALPY, M*KCAL/DAY 33.508 2.630 20.539 KCAL/KG 83.768 31.685 64.794 MOLE FRACTION LIQUID 0.5911 1.0000 1.0000 REDUCED TEMP (KAYS RULE) 0.8910 0.8664 0.8814 PRES (KAYS RULE) 0.4596 0.3814 0.4260 ACENTRIC FACTOR 0.1887 0.1531 0.2010 WATSON K (UOPK) 13.751 14.697 13.503 STD LIQ DENSITY, KG/M3 565.833 507.533 583.383 SPECIFIC GRAVITY 0.5664 0.5080 0.5840 API GRAVITY 118.327 147.025 110.812 --- VAPOR ---
RATE, KG-MOL/DAY 3002.440 N/A N/A K*KG/DAY 160.000 N/A N/A K*M3/DAY 3.682 N/A N/A NORM VAP RATE(1), K*M3/DAY 67.297 N/A N/A SPECIFIC GRAVITY (AIR=1.0) 1.840 N/A N/A MOLECULAR WEIGHT 53.290 N/A N/A ENTHALPY, KCAL/KG 119.965 N/A N/A CP, KCAL/KG-C 0.605 N/A N/A DENSITY, KG/K*M3 43449.017 N/A N/A Z (FROM DENSITY) 0.7255 N/A N/A --- LIQUID ---
RATE, KG-MOL/DAY 4340.105 1880.261 5462.284 K*KG/DAY 240.000 83.014 316.986 M3/DAY 525.734 182.536 687.057 GAL/MIN 96.447 33.487 126.042 STD LIQ RATE, M3/DAY 421.060 163.564 543.358 SPECIFIC GRAVITY (H2O=1.0) 0.5706 0.5080 0.5840 MOLECULAR WEIGHT 55.298 44.150 58.032 ENTHALPY, KCAL/KG 59.637 31.685 64.794 CP, KCAL/KG-C 0.712 0.715 0.715 DENSITY, KG/M3 456.504 454.782 461.367 Z (FROM DENSITY) 0.0717 0.0590 0.0655 (1) NORMAL VAPOR VOLUME IS 22.414 M3/KG-MOLE (0 C AND 1 ATM) Từ kết quả P-3 của Programme file:
MINIMUM REFLUX RATIO 3.95841 FENSKE MINIMUM TRAYS 13.60067 Ta xác định được:
- Số đĩa lý thuyết tối thiểu: 13,6 - Chỉ số hồi lưu tối thiểu: 3,958