Exercise-2

of natural gas is burned in a remelting furnace, which operates 24 hours/day, 300 days in a year. The natural gas analyses  and . Dry combustion air is  excess than theoretical requirements. Flue gas enters the stack at . Volumes are given at  and 1 atmospheric pressure.

It is proposed to install a preheater which will cool the flue gases from  to . It may be assumed that  of the heat recovered from flue gases is transferred to air. Calculate annual fuel saving resulting due to preheater installation. Also calculate carbon affect generation.

Solution:
The heat of combustion values are:

And sensible heat in POC is