Question

Can someone explain the steps behind solving this?

Find the adiabatic flame temperature for reacting 20 wt% pig iron-liquid (Fe-10 mol% C – 3 mol% Si, at 1500 K) and 80 wt% steel scrap (100% Fe at 300K) with 1.25 times the theoretical oxygen (100% O₂ at 300 K) for oxidizing all of the C and the Si and none of the Fe.

Answer 1

We find the adiabatic flame temperature in three ways:

a) an approximate solution using an average value of Cp.

b) a more accurate one using the tabulated evolution of Cp with temperature.

c) or a more accurate solution using the tabulated values for gas enthalpy.

It is given that,

At 1500 K, Fe - 10 mol% and C - 3 mol%

At 300 K, Fe and O₂ is 100%

For an adiabatic process,

(hf) FeCSi (liq) = 10(hf)Fe + 3(hf) C + {(del h) Fe + (del h) C + (del h) Si + (del h) O₂ }

hf = 10(hf)Fe + 3(hf) C - (hf) FeCSi (liq)

hf = 10 kmol(-324287 kJ/kmol) + 3 kmol(-625428 kJ/kmol) - 1.25 kmol(-853672 kJ/kmol)

hf = - 5.478 x 10⁶ kJ.

The adiabatic flame temperature is specified by.

del h = - 5.478 x 10⁶ kJ.