Question 1: One of your fellow Energy Engineers comments that the flue gas leaving the natural gas-fired boiler that you are designing should be at a high temperature because of dew point. Your boss asks you to examine that argument by performing some calculations.
The natural gas boiler that you are designing uses a gas with a composition of CH4-95% and C2H6 - 4% and other inert gases 1%. You have a coal fired facility next door and they use a coal with the following analysis C-73.4% H-4.3%, S-1.1%, N-1.3%. The fuel's proximate analysis is given as follows: Moisture 6.8%, Ash-8.6%, FC- 65.4 and VM 19.2%. The HHV of the Fuel is 13,380 BTUs/lb. The air that is used is ambient at 78 F and 40% relative humidity. This plant is designed to use 22% exc ess air.
Evaluate both cases and show to your boss with calculations whether the dew point is different? If so by how much? And what is the impact?
Question 2:
If 90% of the sulfur dioxide produced has to be captured from the coal fired power plant in problem 1 (500 MW Thermal) by using lime (CaO). What is the flow rate of the CaCO3 that would be required if CaO is produced by calcining CaCO3? The efficiency of sulfur capture is 65%.