$$A CH$4-$fired boiler in an oil refinery needs to deliver $10$

ton$/$hr of steam at $250\backslash$deg C$,10$ bar from feedwater at $25\backslash$deg C$.$ At $90\%$ of

boiler efficiency on a LHV basis and $5\%$ excess air ratio,

determine$1)$ Heat output $[$MWth$]$ hint: msteam$($hout$-$hin$),$ use the steam

tables below for the enthalpy$2)$ Fuel consumption, mfuel $[$kg$/$s$]3)$ Air flow rate required $[$Nm$3/$hr$]4)$ Product gas flow rate $[$Nm$3/$hr$]5)$ O$2$ concentration in the product gas $[$vol$.\%$dry$]6)$ Adiabatic flame temperature $[$K$]7)$ Product gas temperature at the boiler exit $($without heat

loss$)[$K$]$