clear; clc; // Illustration 6.2 // Page: 157 printf('Illustration 6.2 - Page: 157\n\n'); // solution //****Data****// // a = N2 b = H2O L = 9.5*10^(-4);// [cubic m/s] G = 0.061;// [kg/s] Temp = 273+25;// [K] //*****// printf("Construction Arrangement\n"); printf("Use 4 vertical wall baffles, 100 mm wide at 90 degree intervals.\n"); printf("Use a 305 mm dameter, a six bladed disk flat blade turbine impeller, arranged axially, 300 mm from the bottom of vessel\n"); printf("The sparger underneath the impeller will be in the form of a 240 mm dameter ring made of 12.7 mm tubing drilled in the top with 3.18 mm dia holes\n"); Di = 0.305;// [m] Do = 0.00316;// [m] viscocity_a = 1.8*10^(-5);// [kg/m.s] Re_g = 35000; Ma = 28.02;// [kg/kmol] Mb = 18.02;// [kg/kmol] // w = Gas flow rate per orifice w = Re_g*%pi*Do*viscocity_a/4;// [kg/s] N_holes = G/w; Interval = %pi*240/round(N_holes); printf("The number of holes is %d at approx %d mm interval around the sparger ring\n",round(N_holes),round(Interval)); viscocity_b = 8.9*10^(-4);// [kg/m.s] Sigma = 0.072;// [N/m] Density_b = 1000;// [kg/cubic m] D = 1;// [dia of vessel,m] g = 9.81;// [m/s^2] // From Eqn. 6.18 deff('[y] = f7(N)','y = (N*Di/(Sigma*g/Density_b)^0.25)-1.22-(1.25*D/Di)'); N_min = fsolve(2,f7);// [r/s] N = 5;// [r/s] Re_l = ((Di^2)*N*Density_b/viscocity_b); // From fig 6.5 (Pg 152) Po = 5; P = Po*Density_b*(N^3)*(Di^5); h = 0.7;// [m] P_atm = 101.33;// [kN/square m] P_gas = P_atm+(h*Density_b*g/1000);// [kN/square m] Qg = (G/Ma)*22.41*(Temp/273)*(P_atm/P_gas);// [cubic m/s] // From Fig.6.7 (Pg 155) abcissa = Qg/(N*(Di^3)); // abcissa is off scale Pg_by_P = 0.43; Pg = 0.43*P;// [W] Vg = Qg/(%pi*(D^2)/4);// [superficial gas velocity,m/s] check_value = (Re_l^0.7)*((N*Di/Vg)^0.3); vl = %pi*(D^2)/4;// [cubic m] // Since value<30000 // From Eqn. 6.21, Eqn.6.23 & Eqn. 6.24 K = 2.25; m = 0.4; Vt = 0.250;// [m/s] shi = 1; err = 1; while (err>10^(-3)) a = 1.44*((Pg/vl)^0.4)*((Density_b/(Sigma^3))^0.2)*((Vg/Vt)^0.5);// [square m/cubic m] shin = (0.24*K*((viscocity_a/viscocity_b)^0.25)*((Vg/Vt)^0.5))^(1/(1-m)); Dp = K*((vl/Pg)^0.4)*((Sigma^3/Density_b)^0.2)*(shin^m)*((viscocity_a/viscocity_b)^0.25);// [m] err = abs(shi-shin); Vt = Vt-0.002;// [m/s] shi = shin; end // For N2 in H2 Dl = 1.9*10^(-9);// [square m/s] Ra = 1.514*10^(6); // By Eqn. 6.25 Shl = 2.0+(0.31*(Ra^(1/3))); // For dilute soln. c = 1000/Mb;// [kmol/cubic m] Fl = Shl*c*Dl/Dp;// [kmol/square m.s] printf("The average gas-bubble diameter is %e m\n",Dp); printf("Gas Holdup:%f\n",shi); printf("Interfacial area:%e square m/cubic m \n",a); printf("Mass transfer coeffecient:%e kmol/square m.s\n",Fl);