Questions about Simple Tower simulation?
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I would like to ask the experts here: I conducted a simulation for a simple distillation column, and the results showed that the number of plates and the reflux ratio were similar to those in the example problems. However, the heat load on the condenser came out as a positive value, while the heat load on the reboiler was negative – which seems unreasonable. I appreciate any guidance you can provide. Thank you
This is extremely rare; please upload an inp file so everyone can take a look
SIMULATION SCIENCES INC. R PAGE P-3 PROJECT PRO/II VERSION 8.1 ELEC V6.6 PROBLEM OUTPUT SHORTCUT COLUMN SUMMARY 08/24/10 Your license will expire in -42 days. Please contact your IPASSI sales represe ============================================================================== UNIT 1, ‘SCD1’ FEEDS STREAM PHASE ------------ ------ S1 MIXED PRODUCTS ------------- TOTAL STREAM RATES ------------- MOLES WEIGHT LIQUID VOL NORM VAPOR(1) NUM STREAM + PHASE LB-MOL/HR LB/HR FT3/HR FT3/HR SECTION TRAYS ------------ - ---------- ---------- ---------- ---------- ------- ----- S2 L 176.37 7746.69 246.23 66929.53 1 18.90 S3 L 44.09 2809.89 76.25 16732.39 TOTALS 220.46 10556.58 322.48 83661.91 18.90 SPECIFICATIONS PARAMETER COMP. SPECIFICATION SPECIFIED CALCULATED TYPE NUM TYPE VALUE VALUE ----------------- ------- ------------- ---------- ---------- STRM S2 3 MOL RATE 1.000E-02 1.001E-02 STRM S3 2 MOL RATE 1.000E-02 1.002E-02 SUMMARY OF UNDERWOOD CALCULATIONS MINIMUM REFLUX RATIO 24998.38348 FEED CONDITION Q 0.93855 FENSKE MINIMUM TRAYS 18.90430 OPERATING REFLUX RATIO 1.20 * R-MINIMUM TOTAL FEED R/R-MIN M/M-MIN REFLUX DUTY, MM KCAL/HR TRAYS TRAY RATIO CONDENSER REBOILER ----- ---- ------- ------- ------ ---------- ---------- 43 20.69 1.100 2.252 2.7E+04 9.735E+02 -9.732E+02 39 19.20 1.150 2.085 2.9E+04 1.018E+03 -1.017E+03 37 18.01 1.200 1.953 3.0E+04 1.062E+03 -1.062E+03 35 17.04 1.250 1.844 3.1E+04 1.106E+03 -1.106E+03 33 16.23 1.300 1.754 3.2E+04 1.151E+03 -1.150E+03 (1) STANDARD VAPOR VOLUME IS 379.49 FT3/LB-MOLE (60 F AND 14.696 PSIA)
Reply to 3# jihuping: May I ask? In some calculation results, the heat load of the condenser is positive while that of the reboiler is negative; in other calculation results, the heat load of the condenser is negative and that of the reboiler is positive, but their absolute values are exactly the same. What is the reason for this? Please give me some advice. Thank you