Power plants, fossil-fueled combined cycle

Improved efficiency, fossil-fuel power generation through the use of ultra-supercritical steam-cycle plants, integrated gasification combined cycle coal plants, and natural gas combined cycle units. 

Conventional fossil fuel-fired power plants, nuclear power faciUties, cogeneration systems, and combined-cycle faciUties all have one key feature in common some type of steam generator is employed to produce steam. Except for simple-cycle cogeneration faciUties, the steam is used to drive one or... 

Restructuring will promote the introduction of other advanced technologies and practices as well. For example, the use of combined-cycle, gas turbine power plants are expected to proliferate under restructuring. These plants are generally more efficient and more environmentally benign than many fossil fuel plants currently in use. 

Combined aerobic-anaerobic systems, in bioremediation, 25 837 Combined cycle, 10 142-143 Combined cycle fossil fuel plants, 23 236 Combined heat and power (CHP), from biomass, 3 687... 

Power generation plants such as the steam plant, the gas turbine plant, and combined cycle plants require the combustion of a fossil fuel. Now, combustion is a chemical reaction of fuel with an oxidant (usually oxygen), and it makes sense to examine the combustion process more closely and analyze its thermodynamic efficiency. This means that we will examine the furnace/combustor of Figures 9.8, 9.10, and 9.12. We will examine coal and gas combustion at the level needed for thermodynamic analysis, after discussing some commonly used coal combustion processes. 

Single-cycle fuel cell efficiencies range from 47 to 50%. The efficiency of combined-cycle fuel cells is about 60%, and if the generated heat is also recovered (in the form of hot water), the total efficiency can be around 80%. In comparison, the efficiency of gasoline engines is around 25%, of nuclear power plants about 35%, and of subcritical fossil fuel power plants, 37%. 

The primary source of CO2 is the burning of fossil fuels - specifically gas, oil, and coal - so stabilization of atmospheric CO2 concentration will clearly require substantial reductions in CO2 emissions from these sources. For example, one commonly discussed scenario to stabilize at 500 ppm by the mid-twenty-first century suggests that about 640 Gt CO2 (c. 175 GtC) would need to be avoided over 50 years, with further emission reductions beyond 50 years. As references, a 1000 MW pulverized coal plant produces 6-8MtC02 c. 2MtC) per year, while an oil-fired single-cycle plant produces about two-thirds this amount and a natural gas combined cycle plant produces about half this amount. Thus the above scenario would require that the atmospheric emissions from the equivalent of 2000-4000 large power plants be avoided by approximately the year 2050. 

The electric power industry uses three types of fossil fuel power plants coal-fired steam, gas turbine, and combined cycle power plants. The most common and widely used is the pulverized coal-fired steam power plant. Fuel oil can be used in place of... 

Postcombustion capture In this case, the CO2 is separated from the flue gas emitted after the combustion of fossil fuels (from a standard gas turbine combined cycle or a coal-fired steam power plant). CO2 separation is realized at relatively low temperature, from a gaseous stream at atmospheric pressure, and with low CO2 concentration (ca. 5%-25% when air is used during combustion). SO2, NO2, and O2 may also be present in small amounts. 

The research on CLC integration in fossil fuel power plants has been addressed to the use of combined cycle both from natural gas and syngas from coal gasification. Power plants with direct solid conversion have been recently proposed. Summarizing, the following potentialities can be highlighted for CLC technologies ... 

Combined-cycle thermal power plants with natural gas fuel are considered as relatively clean fossil fuel—fired plants compared with coal and oil power plants, and they are dominating new capacity additions because of lower gas production costs using liacking technology, but they still emit CO2 because of the combustion process. 

Natural gas is considered as a clean fossil fuel compared to coal and oil, but still, due to the combustion process, emits a lot of carbon dioxide when it used for electrical generation. The most efficient modem thermal power plants with thermal efficiencies within a range of 50—60% (up to 62%) are, so-called combined cycle power plants (combination of Brayton gas turbine and Rankine steam turbine power cycles) (see Figs. Al.l—A1.4, and Tables Al.l and A1.2), which use mainly natural gas as a fuel. 

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