{ "metadata": { "name": "", "signature": "sha256:82e0373b19da96ab8fd50304caf9cd3e08cf8bad10412b0998bf9110f7a5ae63" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 17 : Design of Catalytic Reactors" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 1, Page 434\n" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "dt=[0.081,0.205,3.6]; #Reactor diameter for the three reactors in m\n", "dte=[0.04,0.12,0.70]; #Equivalent diameters for the three reactors in m\n", "db=[0.05,0.057,0.07]; #Estimated bubble size in the three reactors in m\n", "Kr1=1.3889; #Kinet1ic constant for Reaction 1 in s**-1\n", "Kr2=0.6111; #Kinetic constant for Reaction 2 in s**-1\n", "Kr3=0.022; #Kinetic constant for Reaction 3 in s**-1\n", "dp=60.; #Particle size in micrometer\n", "ephsilonm=0.50; #Void fraction of fixed bed\n", "ephsilonmf=0.55; #Void fraction at minimum fluidized condition\n", "umf=0.006; #Velocity at minimum fluidization condition in m/s\n", "D=2E-5; #Diffusion coefficient of gas in m**2/s\n", "gammab=0.005; #Ratio of volume of dispersed solids to that of bubble phase\n", "uo=0.2; #Superficial gas velocity in m/s\n", "XA=0.9; #Conversion\n", "g=9.81; #Acceleration due to gravity in square m/s**2\n", "\n", "#CALCULATION\n", "Kr12=Kr1+Kr2;\n", "n=len(dt);\n", "i=0;\n", "ubr = [0,0,0]\n", "ub = [0,0,0]\n", "delta = [0,0,0]\n", "ephsilonf = [0,0,0]\n", "gammac = [0,0,0]\n", "gammae = [0,0,0]\n", "Kbc = [0,0,0]\n", "Kce = [0,0,0]\n", "Kf12 = [0,0,0]\n", "Kf3 = [0,0,0]\n", "KfA = [0,0,0]\n", "KfAR = [0,0,0]\n", "KfAR1 = [0,0,0]\n", "tou = [0,0,0]\n", "y = [0,0,0]\n", "SR = [0,0,0]\n", "XA1 = [0,0,0]\n", "y1 = [0,0,0]\n", "y2 = [0,0,0]\n", "tou2 = [0,0,0]\n", "Lf = [0,0,0]\n", "Lm = [0,0,0]\n", "XA2 = [0,0,0]\n", "\n", "import math\n", "while idte:\n", " li=(pi/4*dte*do1+pi/4*do1**2)**0.5;#Pitch if we add dummy tubes\n", "import math\n", "f=li**2-pi/4*do1**2;#Fraction of bed cross section taken up by tubes\n", "dt1=math.sqrt(4/pi*At/(1-f));#Reactor diameter including all its tubes\n", "\n", "#OUTPUT\n", "print 'Superficial gas velocity=%fm/s'%uo\n", "print 'No. of %1.0fm tubes required=%1.0f'%(L,Nt);\n", "print 'Reactor diameter=%fm'%dt1\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Superficial gas velocity=0.460000m/s\n", "No. of 7m tubes required=295\n", "Reactor diameter=7.173176m\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3, Page 444\n" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "db=0.08; #Estimated bubble size in m\n", "dte=2; #Equivalent diameter in m\n", "F1=55.6; #Feed rate of oil in kg/s\n", "XA=0.63; #Conversion\n", "uo=0.6; #Superficial gas velocity in m/s\n", "T1=500.0; #Temperature of reactor in degree C\n", "T2=580.0; #Temperature of regenerator in degree C\n", "Fs=F1*23.3; #Solid circulation rate from Ex.(15.2)\n", "rhos=1200.0; #Density of catalyst in kg/m**3\n", "dpbar=60.0; #Average particle size in micrometer\n", "ephsilonm=0.50;#Void fraction of fixed bed\n", "ephsilonmf=0.55;#Void fraction at minimum fluidized condition\n", "umf=0.006; #Velocity at minimum fluidization condition in m/s\n", "dt=8.0; #Diameter of reactor in m\n", "D=2E-5; #Diffusion coefficient of gas in m**2/s\n", "Kr=8.6; #Rate constant for reaction at 500 degree C in s**-1\n", "Ka1=0.06; #Rate constant for deactivatiion at 500 degree C in s**-1\n", "Ka2=0.012; #Rate constant for regeneration at 580 degree C in s**-1\n", "gammab=0.005; #Ratio of volume of dispersed solids to that of bubble phase\n", "g=9.81; #Acceleration due to gravity in square m/s**2\n", "pi=3.14;\n", "\n", "#CALCULATION\n", "#Parameters for the fluidized reactor\n", "ubr=0.711*(g*db)**0.5;#Rise velocity of bubble from Eqn.(6.7)\n", "ub=1.55*((uo-umf)+14.1*(db+0.005))*dte**0.32+ubr;#Bubble velocity for Geldart A particles from Equation from Eqn.(6.11)\n", "delta=uo/ub;#Fraction of bed in bubbles from Eqn.(6.29)\n", "ephsilonf=1-(1-delta)*(1-ephsilonmf);#Void fraction of fixed bed from Eqn.(6.20)\n", "fw=0.6;#Wake volume to bubble volume from Fig.(5.8)\n", "gammac=(1-ephsilonmf)*((3/(ubr*ephsilonmf/umf-1))+fw);#Volume of solids in cloud to that of the bubble from Eqn.(6.36)\n", "gammae=((1-ephsilonmf)*((1-delta)/delta))-gammab-gammac;#Volume of solids in emulsion to that of the bubble from Eqn.(6.35)\n", "Kbc=4.5*(umf/db)+5.85*((D**0.5*g**0.25)/db**(5.0/4));#Gas interchange coefficient between bubble and cloud from Eqn.(10.27)\n", "Kce=6.77*((D*ephsilonmf*0.711*(g*db)**0.5)/db**3)**0.5;#Gas interchange coefficient between emulsion and cloud from Eqn.(10.34)\n", "import math\n", "#Bed height versus catalyst activity in reactor\n", "a1bar=0.07;#Guess value for average activity in reactor\n", "x=Kr*a1bar;#Value of Kra1 to be used in the following equation\n", "Kf=(gammab*x+1/((1/Kbc)+(1/(gammac*x+1/((1/Kce)+(1/(gammae*x)))))))*(delta/(1-ephsilonf));#Effective rate constant from Eqn.(12.14)\n", "tou=-math.log(1-XA)/Kf;#Space time from Eqn.(12.16)\n", "Lm=tou*uo/(1-ephsilonm);#Length of fixed bed for guess value of a1bar\n", "a1bar1=[0.0233,0.0465,0.0698,0.0930,0.116,0.140];#Various activity values to find Lm\n", "x1 = [0,0,0,0,0,0]\n", "Kf1 = [0,0,0,0,0,0]\n", "tou1 = [0,0,0,0,0,0]\n", "Lm1 = [0,0,0,0,0,0]\n", "\n", "n=len(a1bar1);\n", "i=0;\n", "while i