Thermodynamics power generation

Chapter 1. A brief review of power generation thermodynamics... 

Horlock, J.H. (1997), Aero-engine derivative gas turbines for power generation thermodynamic and economic perspectives, ASME Journal of Engineering for Gas Turbines and Power 119(1), 119-123,... 

In apphcation to electric utihty power generation, MHD is combined with steam (qv) power generation, as shown in Figure 2. The MHD generator is used as a topping unit to the steam bottoming plant. From a thermodynamic point of view, the system is a combined cycle. The MHD generator operates in a Brayton cycle, similar to a gas turbine the steam plant operates in a conventional Rankine cycle (11). 

Power plants based on the Rankine thermodynamic cycle have served the majority of the world s electric power generation needs in the twentieth century. The most common heat sources employed by Rankine cycle power plants are either fossil fuel-fired or nuclear steam generators. The former are the most widely used. 

Fuel cells such as the one shown on Fig. 3.4a convert H2 to H20 and produce electrical power with no intermediate combustion cycle. Thus their thermodynamic efficiency compares favorably with thermal power generation which is limited by Carnot-type constraints. One important advantage of solid electrolyte fuel cells is that, due to their high operating temperature (typically 700° to 1100°C), they offer the possibility of "internal reforming" which permits the use of fuels such as methane without a separate external reformer.33 36... 

The fuel gas from biomass gasifiers can be used to operate gas turbines for local power generation. A gas-turbine power station is similar to a steam plant except that instead of using heat from the burning fuel to produce steam to drive the turbine, it is driven directly by the hot combustion gases. Increasing the temperature in this way improves the thermodynamic efficiency, but in order not to corrode or foul the turbine blades the gases must be very clean which is why many gas-turbine plants use natural gas. 

The steam electric power generation industry is defined as those establishments primarily engaged in the steam generation of electrical energy for distribution and sale. Those establishments produce electricity primarily from a process utilizing fossil-type fuel (coal, oil, or gas) or nuclear fuel in conjunction with a thermal cycle employing the steam-water system as the thermodynamic medium. The industry does not include steam electric power plants in industrial, commercial, or other facilities. The industry in the United States falls under two Standard Industrial Classification (SIC) Codes SIC 4911 and SIC 4931. 

Bell, L.E.PhD BSST, LLC5462 Irwindale Avenue, Irwindale CA 917061bell amerigon.com, 626.815.7430. Alternate Thermoelectric Thermodynamic Cycles with Improved Power Generation Efficiencies. 

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. 

We wish to alert the reader that in the analyses presented above, the results were essentially independent of the type of fuel used. From an efficiency point of view, this may be true, but from a sustainability point of view, it is not. In general, gas is a much cleaner burning fuel than coal and requires less pre- and posttreatment. Even though the standard power generation plants can be made more efficient using thermodynamic analysis (lost work, availability, or exergy analysis), we note that power generation based on fossil fuels is not sustainable since the combustion of these fuels leads to increased... 

We now proceed in a very systematic manner which illustrates the power of thermodynamics - an enormous amount of information is generated by systematic application of elementary steps. Consider first the process of partial differentiation with respect to the variables appearing in Eqs. (1.18.1)-(1.18.4) ... 

The process of the calculation involves a reformer which gets its exergy not from combustion, but as electrical power generated by supplying CO and Fi2 to separate fuel cells which are able to create an excess above the need of the reformer. The invaluable JANAF thermochemical tables (Chase etah, 1985) provided the thermodynamic data. The excess is the chemical exergy of methane. 

---