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Butane (C4H10) is to be burned with air. If 10 mol butane per second are fed wit

ID: 955849 • Letter: B

Question

Butane (C4H10) is to be burned with air.

If 10 mol butane per second are fed with 45% excess air, determine the molar flowrate and composition of the product gases under the following conditions:

     - 98% conversion of butane

     - No carbon monoxide produced

Solve using mole balances

Butane (C_4H_10) is to be burned with air. If 10 mol butane per second are fed with 45% excess air, determine the molar flowrate and composition of the product gases under the following conditions: 98% conversion of butane No carbon monoxide produced Solve using mole balances

Explanation / Answer

10 mol of butane needs 65 moles of O2

65 mol O2 is present in (65 mol / 0.21 ) mol of air = 309.5 mol air

45 % excess of air

total air fed = 309.5 + 0.45 x 309.5 = 448.8 mol

98% conversion.

So moles of butane reacted = 9.8 moles

Moles of butane left =0.2 moles

Moles of O2 reacted = 0.98 x 65 = 63.7 moles

moles of O2 left == ( 0.21 x 448.8 mol - 63.7 moles) ==30.548 moles

moles of CO2 formed = 4 x 9.8 mol = 39.2 mol

moles of water formed = 5 x 9.8 = 49 moles

nitrogen in air doesnot participate in reaction

moles of N2 = 0.79 x 448.8 mol = 354.55 moles

for molar flow rates keep per second for calculated moles

Final composition is

butane = 0.2 mol

nitrogen = 354.55 mol

O2 = 30.548 moles

CO2 = 39.2 mol

water = 49 moles