Combined cycle applications

Separately driven centrifugal compressors are adaptable to low-pressure cryogenic systems because they can be coupled directly to steam turbine drives, are less critical from the standpoint of foundation design criteria, and lend themselves to gas turbine or combined cycle applications. Isentropic efficiencies of 80 to 85% are usually obtained. 

The hfe of a gas turbine depends on the above detailed operational characteristic. It is interesting to note that, for a gas turbine life of 25 years, the life cycle costs can be distributed as 5—10 percent on initial cost, 10-20 percent on maintenance costs and 70-85 percent on cost of fuel. Gas turbines will be very widely used in the 21st century in combined cycle applications as the power source for the world. These combined cycle plants will have efficiencies in the high fifties and will cost between 1000 and 1200 per kW, using 1994 as a monetary benchmark. 

Gas Turbine Cogeneration Combined Cycle Applications (see Cogeneration)... 

The catalytic combustor has great potential in the application of gas turbines in new combined cycle power plants as the NO emissions in high attainment areas will have to be below 2 ppm. 

Another area of success has been in applied materials research. Because of the integral nature of materials to advances in energy production and consumption, the laboratories have developed a number of toughened ceramics. When used as a replacement for steel, they will improve the energy performance characteristics of high-temperature applications for components of combined-cycle power plants and vehicle engines. 

Thermal power plant is more commonly associated with very large central power stations. The capital cost for thermal power plant, in terms of cost per installed kilowatt of electrical generating capacity, rises sharply for outputs of less than some 15 MW. It is for this reason that thermal power plant is not usually considered for industrial applications unless it is the combined cycle or combined heat and power modes. However, for cases where the fuel is of very low cost (for example, a waste product from a process such as wood waste), then the thermal power plant, depending on output, can offer an excellent choice, as its higher initial capital cost can be offset against lower running costs. This section introduces the thermal power cycle for electrical generation only. 

There are two main pressure cycles applicable to combined cycle scheme single or dual pressure ... 

Waste-heat and other special-purpose boilers Special designs provide boilers for waste heat and chemical recovery, waste-to-energy, and combined-cycle installations, pulverized-bed, and even biomass applications. 

Combined-cycle systems are used in both land and marine applications employing diesel engines or gas turbines (which usually provide the first power source) and by large process industries that produce significant heat-containing, by-product waste streams. 

Rating combustion gases from combined cycle plants to use in vegetable crops in greenhouses, in applications in irrigation pipes to prevent clogging and to balance the pH in nutrient solutions. 

In the past years, several projects have been focused in the direct use of flue gases from Combined Cycle Power Plants for developing different applications. In this way, the project CENIT S0ST-C02 has demonstrated the use of flue gases from CCPP in a direct way to control the pH in the cooling water systems with refrigeration tower and Iberdrola has developed an application for power plants. 

Hitachi Coal Energy Application for Gas, Liquid, and Electricity (EAGLE) Coal MHV IGCC, Integrated Coal Gasification Fuel Cell (IGFC) combined cycle 150 360 Oxygen or air 450... 

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... 

Trevino, M. C. (2002). Integrated Gasification Combined Cycle Technology IGCC. Its Actual Application in Spain. ELCOGAS, Puertollano Club Espanol de la Energia. 

For combined hydrogen production and C02 capture several novel technologies are in development, most of them for the application in a pre-combustion C02 capture combined cycle. The main focus is to reduce the efficiency penalties and other associated costs of CO2 capture. The most important technologies in the R D phase, membrane reactors and sorption-enhanced reactors, are described below, with special attention paid to the catalytic aspects. 

The combined cycle is also applicable to dedicated power production. When the steam from the waste heat boiler is fed to a condensing turbine, overall conversion efficiencies of fuel to electricity in excess of 50% can be achieved. A few public utility power plants use this cycle, but in general utilities have been slow to convert to gas turbines. Most electricity is generated by the cycle shown in Figures 5d and 6d. 

Figure 1. A schematic of an integrated coal gasification system for fuel cell or combined-cycle-power-generation applications.

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