A coal with an ultimate gravimetric analysis of $80\%$ C$,5\%$ H$2,5\mathrm{.}4\%$ O$2,0\mathrm{.}63\%$ N$2,0\mathrm{.}89\%$ S and $8\mathrm{.}08\%$ Ash is burned in an industrial boiler. Calculate the adiabatic flame temperature with a stoichiometric air supply Assume the air and coal enter the boiler at $25$oC $.$ Assume that the effect of ash on the energy balance can be ignored.

From the following options choose ONE only to complete

Option $1-$ Determine the impact on the adiabatic flame temperature of varying the air supply from stoichiometric to $300\%$ excess air and identify the trends. Explain the reasons for the trends observed and how these are used in temperature control using gas recycling

Option $2$ Formulate the energy equation to account for the effect of ash on the adiabatic flame temperature and determine the difference between the ash$/$non ash calculated value of adiabatic temperature. You may need to assume a physically consistent ash composition.