The dry-ash-free proximate composition of coal is 38.86 wt.% volatiles and 61.14 wt.% fixed carbon. Assume the volatiles can be simplified as the following molecule The average molar mass of this compound is 4.857 g/mole and the enthalpy of formation is -140000 kJ/kmol. This coal is burned in 120% theoretical air. Assume complete mixing and combustion. Assume the C, H and N in the volatile component of the fuel oxidised completely to CO2, H2O and NO2. The formation enthalpy for solid Carbon is 0 kJ/kg.

a)What are the molar fractions of the volatiles and fixed carbon in the coal (mol%)?

b)Write the balanced stoichiometric combustion equation?

c)Write the balanced combustion equation for 120% theoretical air?

d) What is the molar air-to-fuel ratio?

e) If the products and reactants are at 25°C and 100 kPa, what is the LHV of coal in MJ/kg?

f) How many tonnes of coal with the above LHV is burned in a 700MWe boiler unit in 1 day if the thermal

efficiency is 34.5%?

Answer rating: 100% (QA)

a The molar fractions of the volatiles and fixed carbon in the coal are Volatiles 8000 Fixed carbon 2000 The molar fractions of the volatiles and fixe... View the full answer