Question 476Steam Plants - Assistant Engineer

The correct answer is D) dew point temperature of the stack gases. The dew point temperature of the stack gases is a key factor in determining the minimum feed water inlet temperature to a boiler economizer. This is because the economizer is designed to extract heat from the exhaust gases before they are vented, and the feed water inlet temperature must be kept above the dew point to prevent condensation and potential corrosion in the economizer. The other options, such as desuperheater outlet temperature, steam bled off the LP turbine, and superheater inlet temperature, are not directly related to the minimum feed water inlet temperature required for the economizer to function effectively.