142 tons per year.Sieve Plate is chosen because the plating efficiency is high (60- 80%) and its cheaper maintenance compares to bubble cap type and also gives the lowest pressure drop among...

Design Project Equipment sizing


142 tons per year.Sieve Plate is chosen because the plating efficiency is high (60- 80%) and its cheaper maintenance compares to bubble cap type and also gives the lowest pressure drop among others.Unlike Bubble caps, which are prone to corrosion and fouling, sieve plates actual have a more stability throughout the user experiences. 4.1.2 Method of Design and Assumptions Table 4.1: Method of Design Method of Design Mc-Cabe- Thiele Method The McCabe–Thiele method is considered to be the simplest and perhaps most instructive method for the analysis of binary distillation. Plate Design I.Provides a better liquid distribution. II. Provide sufficient liquid hold-up for good mass transfer (high efficiency). III. Have sufficient area and spacing to keep the entrainment and pressure drop within acceptable limits. IV. Have sufficient downcomer area for the liquid to flow freely from plate to plate Assumptions Plate spacing = 500 mm pL (Bottom) = 655 kg/m3 pL (Top) = 570 kg/m3 143 R = 8.314 J/kmol T top = 65 oC T bot = 273 oC Flooding Velocity = 85% Pressure Top = 101 325 pa Pressure Bottom = 114 153 pa MW (Ethylene) = 28.05 g/mol MW (Hexane) = 86.15 g/mol Surface Tension (top) α = 35 x 10-3 N/M Surface Tension (Bottom) α = 18.43 x 10-3 N/M Flooding velocity = 0.85 Reflux Ratio = 2.74286 Liquid Turndown Rate = 0.7 4.1.3 Step by Step Calculation Table 4.2: Mole Fraction in Distillation Column Liquid Molefrac Ethylene Dichloride Vapor Molefrac Ethylene 0 0 0.8843104 0.0196078 0.9718481 0.0392156 0.989271 0.0588235 0.9947939 0.0784313 0.9970794 0.0980392 0.998197 0.1176471 0.9988091 0.1372549 0.9991729 0.1568627 0.999403 0.1764706 144 0.9995558 0.1960784 0.9996611 0.2156863 0.9997362 0.2352941 0.9997911 0.254902 0.9998322 0.2745098 0.9998635 0.2941176 0.9998878 0.3137255 0.9999069 0.3333333 0.9999221 0.3529412 0.9999344 0.372549 0.9999444 0.3921569 0.9999526 0.4117647 0.9999594 0.4313725 0.9999651 0.4509804 0.9999699 0.4705882 0.9999739 0.4901961 0.9999774 0.5098039 0.9999803 0.5294118 0.9999828 0.5490196 0.999985 0.5686275 0.9999869 0.5882353 0.9999886 0.6078431 0.99999 0.627451 0.9999913 0.6470588 0.9999924 0.6666667 0.9999933 0.6862745 0.9999942 0.7058824 0.999995 0.7254902 0.9999956 0.745098 0.9999962 0.7647059 0.9999968 0.7843137 0.9999972 0.8039216 0.9999977 0.8235294 0.9999981 0.8431373 0.9999984 0.8627451 0.9999987 0.8823529 0.999999 0.9019608 0.9999992 0.9215686 0.9999995 0.9411765 0.9999997 0.9607843 0.9999998 0.9803922 1 1 145 Figure 4.1 : Distillation Column *R = 1.5Rmin Figure 4.2: Vapour – Liquid Equilibrium Diagram 146 1. Rmin Y=( ???? ????+1 ) ? + ( 1 ????+1 ) ?? (4.1) Intercept C = ( ?? ????+1 ) C= 0.99 ????+1 C through graph above = 0.3 Rmin = (0.99/0.3) -1 = 2.3 R = 1.5Rmin =1.5(2.3) = 3.45 2. Minimum Number of Stages Nmin Nmin = 8 stages 3.Number of theoritical Stages N Y=( ? ?+1 ) ? + ( 1 ?+1 ) ?? (4.2) Intercept C = ( ?? ?+1 ) C = ( 0.99 3.45+1 ) C=0.2224 N = 17 stages 147 4. Overall Column Efficiency Eo Eo = ? ????? ? ???? (4.3) Number of ideal stages = 17 -1 (Reboiler) = 16 Stages Number of Actual Stages = 16 0.60 =27 Stages 5. Column Sizing Total Feed rate : 12956.05 kg/h Mol.Weight of Feed : 0.5 x 98.96 + 0.5 x 28.05 = 63.51 In term of Molar flow rate : Total Feed rate / Mol.Weight of Feed : 204 kmol/h D + B = 204 0.99D + 0.005B = 204 0.99(204-B) + 0.005(B) = 204(0.5) B = 101.48 kmol/h D =102.52 kmol/h 6. Vapour Rate V=D(1+R) (4.4) V= 102.52(1+3.45) V = 456.214 kmol/h Distillation Column Sizing and Configuration Table 1 Mass Balance for DST-2 Equipment DISTILLATION COLUMN 2 Operating condition T= 80 oC, P= 19 atm Input/ Output Input Output Stream name S10 S11 S12 Component Phase kmol/hr Phase Kmol/hr Phase kmol/hr Methanol L 44.33 L 43.88 L 0.45 Recycle Methanol - - - - - - Iso Butylene - - - - - - Di-isobutylene - - - - - - MTBE - - - - - - Water L 376.94 L 3.77 L 373.17 SUB-TOTAL (kmol/hr) 421.27 47.65 373.62 TOTAL (kmol/hr) 421.27 421.27 Reference state: Methanol and Water (L, 80oC, 19atm). Table 2: Energy balance of DST-2 DST-2 IN   OUT STREAM COMPONENT PHASE T (oC) & P (atm) nin (kmol/hr) Hin (kJ/mol) STREAM COMPONENT PHASE T (oC) & P (atm) nout (kmol/hr) Hout (kJ/mol) 10 Methanol L 80oC; 19 atm 44.33 -6.61 Vapour Methanol G 64.7oC; 19atm 96.55 35.17 Water L 376.94 -6.032 Water G 8.29 41.82         Liquid Methanol L 90oC; 19atm 1.48 -0.88         Water L 1242.66 -0.75 REFLUX Methanol L 50oC; 19atm 52.66 2.60 Total noutHout (kJ/hr) 2,803.96 Water L 4.52 2.26 BOIL UP Methanol L 100oC; 19atm 1.03 -1.82 Water L 869.49 -1.51 Total ninHin (kJ/hr) -3732.30