A fuel containing 50 mol% C2H6 and 50 mol% C3H8 enters a furnace at a rate of 20

Question

A fuel containing 50 mol% C2H6 and 50 mol% C3H8 enters a furnace at a rate of 200 mol/s, at 200 oC and Pgauge=5.0 atm. Air is fed to the furnace in a separate stream at 40% excess. All of the fuel is burned—the product contains no C2H6 and no C3H8. The ratio of CO2/CO in the product stream is 10/1 (in moles/moles).  
Ideal gas constant, R= 0.08204 L atm/(mol K).

Calculate the partial pressure of C2H6 in the feed stream__________

Calculate the volumetric flow rate of the fuel in the feed stream, in L/s __________

Calculate the feed rate of oxygen, in mol/s___________________

Calculate the feed rate of air, in mol/s___________________

Calculate the molar flow rate of each chemical species in the product stream, in mol/s.   Write answers on the product stream,

Explanation / Answer

Partial pressure of C2H6= Mole fraction * total pressure

Since feed containd 50 mo% C2H6 and 50 mlo% C3H8, mole fraction of C2H6=0.5

1.Partial pressure of C2H6=0.5*5= 2.5 atm

2. Volumetric flow rate, V= nRT/P =200* 0.0824 L.atm/mole.K *(200+273)/5 L/s=1553 L/s

3. The combustion reactions are

C2H6 + 3.5O2 ------>2CO2 + 3H2O and C3H8 +5 O2 -->3CO2 + 4H2O

Moles of C2H6= 200*0.5= 100 mol/s moles of C3H8=100 mol/s

Moles of oxygen for complete combustion of C2H6= 100*3.5=350 mol/s and moles of Oxygen for complete combustion of C3H8= 100*5=500 mol/s

Total oxygen required = 350+500= 850 mol/s

Supplied oxygen =40% excess, oxygen supplied =850*1.4= 1190 mol/s

4. Air contains 21% O2 and 79% N2, moles of air supplied = 1190/0.21=5667 mol/s

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