//clear// clear; clc; //Example 22.5 //Solution //Equlibrium data are shown in Fig.22.22 //By a heat balance similar to that of Eample 22.3 //The temperature rise of the liqui was estimated //to be delta_T = 12.5; //[C] //Basis: dry_gas_in = 100; //[mol] sol_in = 140; //[mol] N2_in = 87; //[mol] CO2_in = 10; //[mol] EO_in = 3; //[mol] N2_out = 87; //[mol] CO2_out = 10; //[mol] EO_out = 3*0.02; //[mol] IN = N2_in+CO2_in+EO_in; //[mol] OUT = N2_out+CO2_out+EO_out; //[mol] //Assuming negligible CO2 absorption and neglect effect of H2O on //gas composition. //At top: xt = 0.004; yt = EO_out/OUT; //Moles of EO absorbed EO_abs = 3*0.98; //[mol] //Moles of EO absorbed in water EO_H2O = 140*0.0004; //[mol] //At bottom: xb = (EO_abs+EO_H2O)/(140+EO_abs); yb = 0.03; //From Fig 22.22 y = [0.03,0.015,0.005,0.0006]'; delta_y1 = [0.008,0.0006,0.0024,0.0003]'; for i = 1:length(y)-1 delta_y = y(i)-y(i+1); delta_yL = (delta_y1(i)-delta_y1(i+1))/log(delta_y1(i)/delta_y1(i+1)); Noy1(i) = delta_y/delta_yL; end Noy = sum(Noy1); //Column diameter: //Using generalize pressure-drop correlation, Fig.22.6 //Based on the inlet gas, Mbar = 0.87*28+0.1*44+0.03*44; //At 40C, rho_y = 30.1/359*20*273/313 //[lb/ft^3] rho_x = 62.2; //[lb/ft^3] //Let A = Gx/Gy*sqrt(rho_y/(rho_x-rho_y)) A = 1.4*18/(1*30.1)*sqrt(rho_y/(rho_x-rho_y)); //From Fig. 22.6, for delta_P = 0.5; //[in.H2O/ft] //Let B = Gy^2*Fp*mux^0.1/(rho_y*(rho_x-rho_y)*gc) B = 0.045; //From Table 22.1, Fp = 40; mu = 0.656; //[cP] //so Gy = sqrt(B*(rho_y)*(rho_x-rho_y)*32.2/(Fp*mu^0.1)); //[lb/ft^2-h] //or Gy = Gy*3600; //[lb/ft^2-s] Gx = 1.4*18/(1*Mbar)*Gy; //[lb/f^2-s] //For a feed rate F = 10000*Mbar; //[lb/h] S = F/Gx; //[ft^2] D = sqrt(S*4/%pi); //[ft] //Column heigth: //From Fig. 22.20 at Gy = 500 and Gx = 1500 Hy_NH3 = 1.4; //[ft] mu_40 =0.0181*10^-2; //[P], Appendix 8 Dv = 7.01*10^-3; //[cm^2/s], from Eq.(21.25) rho = 2.34*10^-2; //[lb/ft^3] Nsc = mu_40/(rho*Dv); //Form Table 22.1, fp = 1.36; Hy_EO = 1.4*(1.1/0.66)^0.5*1/1.36*(Gy/500)^0.3*(1500/Gx)^0.4; //[ft] //Form Fig. 22.19, Hx_O2 = 0.9; //[ft] Gx1 = 1500; mu1 = 0.00656; //[P] rho1 = 1; //[lb/ft^3] //Using Eq.(21.28) Dv1 = 2.15*10^-5; //[cm^2/s] Nsc1 = mu1/(rho1*Dv1); //Using Eq.(22.35), with the correction factor fp and Nsc = 381, //for O2 in water at 25 C Hx_EO = Hx_O2*(Gx/(mu1*100)/(Gx1/0.894))^0.3*(Nsc1/381)^0.5/1.36; //[ft] //From Fig 22.22, the average value of m m = 1.0; //From Eq.(22.30) HOy = 1.71+(1*0.96)/1.4; //[ft] disp(NOy,'number of transfer units required') disp('ft',D,'diameter of the column') disp('ft',HOy,'packing height')