A processed coal, consisting only of carbon and ash, is burned at a rate of 30,000 kg/hr. The combustion occurs with 20% excess air, and the entire ash is collected after combustion at a rate of 4,500 kg/hr. 

Determine (a) the ultimate analysis of the coal, (b) the AF ratio, kg air/kg fuel; (c) the volume of air supply required at 101 kPa and 27°C: and (d) the higher heating value of the coal, kJ/kg.