Fossil Fuel Power Plant Flashcards
Give a general description of how thermal power plants operate.
Heat of combustion of coal/gas/waste used to boil water and generate steam. This steam drives a turbine and finally a generator. Steam is then cooled to water and begins the cycle once more.
What are largest standard turbo-generator units rated at?
660MW
What is formula of Carnot efficiency?
n=1-(T2/T1)
T1= temp of superheated steam
T2= temp of fluid rejected to surroundings
What is formula for endoreversible efficiency?
n=1-sqrt(T2/T1)
What is the realistic value of efficiency for thermal power plants?
35% and usually this value is not exceeded
What are ways to improve efficiency?
Provide combined heat and power by designing plant to produce useful heat as well as useful electricity.
In the combined cycle gas turbine (CCGT) process, what is the efficiency?
Around 55% for 2 stage process. For single stage it is around 30%
Name four power plant types.
Fossil fuel electricity generating plant
Gas turbine electricity generating plant
Combined cycle gas turbine generating plant
Small scale generating plant
Give examples of emissions.
CO2, soot, unburned hyrdocarbons, sulphur dioxide (SO2) and oxides of nitrogen (NOx)
How is sulphur dioxide created?
Burning of fuels such as oil and coal
How is NOx created?
High temp combustion in air
What are ways of reducing these emissions?
Careful control of combustion process and treatment of exhaust fumes by chemical action or filtration.
What are the CO2 emissions (in kg/kWh) of coal, oil and gas?
Coal - 0.9
Oil - 0.7
Natural gas - 0.2
Net CO2 emissions of biofuels can be quantified at net 0, how?
If biofuels are used in a sustainable manner (e.g. replanting as consumed) this can close the carbon cycle thus reducing the emissions to net 0.
What is carbon capture?
Capturing carbon emissions from power plants and storing them underground in an effort to reduce global warming.
