Combined cycle power plants modem

In a combined cycle power plant (CCPP), or combined cycle gas turbine (CCGT) plant, a gas turbine generator produces electricity and the waste heat is used to make steam for generating additional electricity via a steam turbine this last step enhances the efficiency for electricity generation to about 60%, because the temperature difference between the input and output heat levels is higher leading to an increase in the Carnot efficiency. Most modem power plants in Europe and in North America are of this type. 

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. 

Figure A1.4 (a) Modem combined cycle power plant schematic and (b) T—s diagram. Partially based on data from MHI and Siemens. 

Because of the simplicity and reUabiUty of the Rankine cycle, faciUties employing this method have dominated the power industry in the twentieth century and typically play an important role in most modem combined-cycle faciUties. Water is the working fluid of choice in nearly all Rankine cycle power plants because water is nontoxic, abundant, and low cost. 

It will be some time before fuel cells become available as a realistic commercial alternative for power generation applications. In order to compete with modem gas turbines/combined-cycle equipment, fuel cell plants will have to produce high-temperature waste heat, operate at an electrical efficiency of... 

In general, the major driving force for all advances in thermal power plants and NPPs is thermal efficiency and generating costs. Ranges of gross thermal efficiencies of modem power plants are (1) combined-cycle thermal power plants (up to 62%) (2) supercritical-pressure coal-fired thermal power plants (up to 55%) (3) C02-cooled reactor NPPs (up to 42%) (4) sodium-cooled fast reactor NPPs (up to 40%) (5) subcritical-ptessure coal-fired thermal power plants (up to 40%) and (6) modem water-cooled reactors (30—36%). 

Table 3.8 compares the estimated costs of potable water production through seawater desalination cogeneration with conventional and VHTR power plants (Sato et al., 2014). The conventional plant is based on a modem gas turbine combined cycle (GTCC) power plant at 55% power generation efficiency. The VHTR cogeneration system is that described in Section 3.4.2.2. The costs were evaluated by an original equipment manufacturer (OEM) vendor active in the Middle East desalination plant constmction. The vendor carried out the plant equipment design and evaluated the required operation and maintenance. The cost estimation was then developed based on the vendor construction and operation know-how of comparable-scale MSF plants. 

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