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Calculate the mass of air supplied. Also calculate individual and total mass of products of combustion per kg of fuel if 30% of excess air is supplied for combustion.

The ultimate analysis of a solid fuel is as follows:- - C = 78%, O2 = 3%, H2 = 3%, S = 1%, moisture= 5% and ash content = 10% - Mumbai university > MECH > SEM 3 > THERMO

Marks: 10M

Year: Dec 2013

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Element Percentage present in fuel
Carbon (C) 78
Hydrogen (H) 3
Sulphur (S) 1
Oxygen (O) 3
Ash 10
Moisture 5

Consider 100 kg of fuel.

For Carbon, the chemical reaction is given as:

C+O2CO2

12    32     44

12kg of Carbon requires 32 kg of Oxygen and forms 44kg of Carbon Dioxide

Therefore 78 kg of Carbon requires (3212×78)=208kg of Oxygen to form 286 kg of Carbon Dioxide.

For Hydrogen, the chemical reaction is given as:

2H2+O22H2O

4         32        36

4 kg of Hydrogen requires 32 kg of Oxygen to form 36 kg of Water

Therefore 3 kg of Hydrogen requires (324×3)=24kg of Oxygen and forms 27 kg of Water.

For Sulphur, the chemical reaction is given as:

S+O2SO2

32    32     64

32kg of Sulphur requires 32 kg of Oxygen and forms 64kg of Sulphur Dioxide

Therefore 1 kg of Carbon requires (3232×1)=1 kg of Oxygen and forms 2 kg of Sulphur Dioxide.

Total Oxygen Required = 208 + 24 + 1 = 233 kg

Total Theoretical Oxygen to be supplied = 233 – 3 = 230 kg

Therefore Total Theoretical Air to be supplied = (10023×230)=1000kg for 100kg of fuel

= 10kg / kg of fuel

Actual Air to be supplied = Theoretical Air x Excess Factor

= 10 x 1.3

= 13 kg /kg of fuel

Now Total Mass of Combustion products = Mass of (CO2+H2O+SO2)

= 2.86 + 0.27 + 0.02

= 3.15 kg /kg of fuel

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