Steam Reforming of Propane
Authors: Housam Binous and Ahmed Bellagi
Steam Reforming of Propane
Authors: Housam Binous and Ahmed Bellagi
Authors: Housam Binous and Ahmed Bellagi
Steam reforming is a method for producing hydrogen and carbon dioxide starting from hydrocarbons. In this Demonstration, a feed stream, composed of propane and steam, enters a reactor at 150 °C and 1 atm. We assume that the propane molar flow rate in the feed stream is 1 mol/s and that the steam/propane molar ratio in the feed stream is 9.Using a nickel-based catalyst placed in tubes, steam reforming of propane (reaction R1) occurs according to the following reaction:(g)+3O(v)→3CO(g)+7(g).Another reaction, the water-gas shift reaction (reaction R2) also takes place in the reactor and produces more hydrogen according to.The standard heat of reaction R1 is . Thus, this reaction is endothermic. On the other hand, reaction R2 is mildly exothermic, and its standard heat of reaction is . Thus, heat must be added to the reformer, using burners to heat the tubes. You can set the value of the heat added (in kW) to the reactor >0, as well as the temperature of the outlet stream. The outlet stream’s pressure is equal to 1 atm. Assume that the propane is entirely consumed, so that the extent of reaction R1 is =1mol/s.The graphic shows the labeled process flowchart and , the extent of reaction R2. For this purpose, we make use of the energy balance equation for reactive systems: =Δ=- (i.e. the heat of formation method). The specific enthalpies of all components are computed using the temperature-dependent expressions of the constant-pressure heat capacities given in[1, Appendix B2]. In addition, we chose as reference states the elemental species (g), (g) and at 25 °C and 1 atm. All of the heat requirements for the formations are obtained from[1, Appendix B1].References:[1] R. M. Felder and R. W. Rousseau, Elementary Principles of Chemical Processes, 3rd ed., New York: John Wiley & Sons, 2004.
C
3
H
8
H
2
H
2
CO(g)+O(v)→(g)+(g)
H
2
CO
2
H
2
497.73kJ/mol
-41.15kJ/mol
Q
ξ
1
ξ
2
Q
H
∑
i
out
n
i
H
i
∑
i
in
n
i
H
i
H
2
O
2
C(s)
In[]:=
To=700;(*outlettemperaturein°C*)Q=720;(*addedheatinkW*)
DHr1=-3110.52+3×241.83+103.8DHr2=-393.5+241.83+110.52(*computeheatsofreactions1and2inkJ/molbasedonheatsofformationofpropane,CO,CO2andH2O*)
Out[]=
497.73
Out[]=
-41.15
In[]:=
HIC3H8=-103.8+NIntegrate[68.03210^-3+22.5910^-5T-13.1110^-8T^2+31.7110^-12T^3,{T,25,150}];HIH2O=-241.83+NIntegrate[33.4610^-3+0.688010^-5T+0.760410^-8T^2-3.59310^-12T^3,{T,25,150}];HOH2O=-241.83+NIntegrate[33.4610^-3+0.688010^-5T+0.760410^-8T^2-3.59310^-12T^3,{T,25,To}];HOCO2=-393.5+NIntegrate[36.1110^-3+4.23310^-5T-2.88710^-8T^2+7.46410^-12T^3,{T,25,To}];HOCO=-110.52+NIntegrate[28.9510^-3+0.41110^-5T+0.354810^-8T^2-2.22010^-12T^3,{T,25,To}];HOH2=NIntegrate[28.8410^-3+0.0076510^-5T+0.328810^-8T^2-0.869810^-12T^3,{T,25,To}];(*specificenthalpiesofallcomponentsininletandoutletstreams*)
sol=x/.First@Flatten@Solve[Q-HIH2O9-HIC3H81+HOCO2x+HOCO(3-x)+HOH2(7+x)+HOH2O(6-x),x](*heatofformationmethodyieldstheextentofreaction2inmol/s*)
Out[]=
2.24881
In[]:=
Graphics[Darker@Yellow,Opacity[0.9],EdgeForm[{Black,Thick}],Rectangle[{0,0},{2,2}],Opacity[1],Style[Text[Row[{"Steam\nReformer"}],{1,1},{0,0}],20,Darker@Black],Opacity[1],Thickness[0.01],Arrowheads[Large],Darker@Red,Arrow[{{-1.5,1.0},{0,1.0}}],Style[Text[Row[{Style["inlet stream",Black,16,Bold],"\n","1 mol/s of propane","\n","9 mol/s of water","\n",NumberForm[150,{5,1}]," °C"," 1 atm"}],{-1.15,1.35},{0,0}],14,Darker@Red],Darker@Blue,Arrow[{{2,1.45},{3,1.45}}],Style[Text[Row[Style["outlet stream",Black,16,Bold],"\n",Row[{NumberForm[7+sol,{5,3}]," mol/s of hydrogen"}],"\n",Row[{NumberForm[6-sol,{5,3}]" mol/s of water"}],"\n",Row[{NumberForm[sol,{5,3}]," mol/s of "}],"\n",Row[{NumberForm[3-sol,{5,3}]," mol/s of CO"}],"\n",NumberForm[To,{5,1}]," °C"," 1 atm","\n",Row[" = ",NumberForm[sol,{5,3}]," mol/s"]],{3.5,0.75},{0,0}],14,Darker@Blue],Darker@Gray,Dotted,Arrow[{{1.0,-0.25},{1.0,0.25}}],Gray,Dashed,Arrowheads[Large],Thickness[0.015],Style[Text[Row[{NumberForm[Q,{5,1}]," kW"}],{1.0,-0.35},{0,0}],14,Darker@Gray],AspectRatio1.0,ImageSize1.05{450,340}]
CO
2
ξ
2
Out[]=
WefindcloseagreementwiththeresultsobtainedbyAspen-HYSYS:
