$20.$ Optimizing Combustion Air in Pulverized Fuel System:

A pulverized fuel combustion system uses coal with a calorific value of $28$ MJ$/$kg$.$ If $2500$ kg of coal are burned per hour and stoichiometric air required for complete combustion is $11$ m$^3/$kg of coal, calculate the total air needed for combustion, and determine if using $10\%$ excess air is beneficial in terms of combustion efficiency.