Let me give you an example, so you can take this as reference and calculate fuel required for any capacity of Boiler for any fuel.
Boiler Capacity – 10000kg/hr
Steam Pressure – 10.5 kg/cm2(g)
Steam Temperature – 185.5 Deg c (Saturated Steam)- You will get this value in steam table
Enthalpy of Saturated Steam – 664.2 kcal/kg-You will get this value in steam table
Enthalpy of Feed water – 105 kcal/kg – You will get this value in steam table
Fuel – Bagasse with 50% moisture
Calorific value(GCV) – 2272 kcal/kg- (It is the amount of heat liberated in Kcal by the complete combustion of 1 kg of fuel)
Boiler Efficiency – 80 % on GCV Basis ( It can be calculated by deducting the losses. Carbon loss, radiation loss, dry gas loss, H2O in Air, H2O in Fuel etc)
These parameters are required to calculate fuel consumption to boiler.
Fuel Required = Heat Input required (kcal/hr.) / Calorific Value of that fuel (kcal/kg)
Heat Input required (kcal/hr.)= (Boiler Capacity x (Steam Enthalpy – Feed water Enthalpy))/(Boiler Efficiency)
For above parameters
Heat Input required = 10000 x (664.2 -105)/0.8 = 699,0000 kcal/hr
Fuel Required = 6990000/2272 =3076.58kg/hr
Fuel Required for 10 TPH Boiler is 3076.58 kg/hr.
That means by burning 3076.58 kg/hr of of Bagasse, you can generate 10000 kg/hr saturated steam at 10.5 kg/cm2(g) pressure.