The conversion of solid wastes to innocuous gases can be accomplished in incinerators in an

environmentally acceptable fashion. However, the hot exhaust gases must be cooled down to save

energy. An economic feasibility study indicates that solid municipal waste can be burned to a gas

containing $9\mathrm{.}2\%C{O}_2,1\mathrm{.}5\%CO,7\mathrm{.}3\%O_2$ and $82\%N_2($on a dry basis$).$

a$)$ What is the enthalpy difference for this gas between the bottom and the top of the stack if the

temperature at the bottom of the stack is $400C$ and the temperature at the top is $170C?($Ignore

the water vapor in the gas$).$

b$)$ If the stack gas flowrate is measured as $250\frac{m^3}{m}in$ at $750mmHg$ at $400C,$ calculate the amount

of heat that must be removed from the stack gas.

c$)$ The heat removed from the stack gas can be used to produce steam. If the saturated water at $5$

bar is fed to the economizer, calculate the mass flowrate of steam at $350C?$

d$)$ Calculate the dew point of the stack gas if the relative humidity of flue gas is measured as $1\mathrm{.}5\%$

at the top of the stack.

e$)$ Calculate the composition of the stack gas in wet basis.