Therefore, the results of these technologies will be less impressive in locations with a higher average humidity. The results show that the electric ehiller system yields maximum power capacity enhancement, even alter accounting for the large parasitic needs of the ehiller system. The ehiller system in this example is designed to cool the inlet air to 7 °C. and is able to achieve output capacities that exceed the rated capacities. Another advantage of the ehiller system is that it can he designed to achieve almost constant output independent of the ambient dry-and wet-bulb temperatures. The ehiller system, however, costs more to install than the evaporative cooling and fogging systems. Economic benefits The economic benefits of the three technologies are illustrated in Figure 5. The basis for the installed costs is: O Cogeneration gas turbine plant (no cooling):US$750,000/MW O Wetted media (evaporative cooling): S19,000/MW gas turbine capacity at ISO O Fogging: S19,000/MW gas turbine capacity at ISO O Electric ehiller: $800/RT. The results show that the total plant capital cost, expressed in $/MW, is lower for the plants with turbine air inlet cooling than those for the uncooled system. Plant owners have only two options for increasing the output capacity of an uncooled plant: add another gas turbine, or install turbine air inlet cooling for the existing gas turbine. The economic benefits of turbine air inlet cooling become significantly more apparent when the capital costs per unit of output enhancement are compared - see Figure 6. The results show that the incremental capital cost for enhancing plant capacity by 1 M\Y is significantly lower far turbine air inlet cooling technologies than installing another uncooled gas turbine. The results of the various turbine air inlet cooling technologies depcnd in part on the plant location. Therefore, the economics of these technologies will be different for plants located elsewhere. Selecting optimum technology The discussion above relates to a situation where the ambient dry-bulb and wet-bulb temperatures are 31°C and 16°C respectively. However, this information is not sufficient to decide whether turbine air inlet cooling is economically attractive and. if so. which cooling technology would be the most economically attractive. Such estimates require calculations using hourly weather data for the whole year, and alsa require information for the cost of fuel, power demand profile, and market value of the power produced (which might vary with the time of day). SUMMARY The big advantage offered by turbine air inlet cooling is that it enables the turbine to produce increased output, and ensures that output can be maintained at a high level when the ambient temperature is high. "Kojenerasyon: Yüksek Verim, Temiz Çevre, Enerjide Yeniden Yapılanma" ARTICLE / MAKALE a 840 830 3 820 ~ -- V't 810 -o 800 C ~ ::ı 790 o ~ 780 cJ) C o 770 o u 760 -5 750 -~ :B b u 950 ~ 'ö.. 900 "' u c 850 "' c::: 800 750 700 No Evap. Fogging Chiller cooliııg cooling Figııre 5. Toıal planı invesııııe11ı for aıı (a) 83.5 MW aııd (b) 42 MW gas ıurbiııe - eflect ofııırbiııe air inlet cooliııg a 1000· 800 3 600 ~ V't -o 400 C ~ ::ı o 200 ..c C. 15 16 :B o u c b QJ E QJ u C "' ..r:. 950 ~ C' 900 'ü "' o.. 850 "' u 800 750 700 14 13 No Evap. Fogging Chiller cooliııg cooling Figııre 6. lııcreıııeıııal capacity eıılıcııceıııent cosıfor aıı {a) 83.5 MW aııd {b) 42 MWgas ııırbiııe - eflecı ofııırbiııe air inlet cooliııg The biggest advantages accrue when ambient temperatures are high: as a result, turbine air inlet cooling is most economic in hat locations. in cool locations, the economic case is weaker. ENERJi & KOJENERASYON DÜNYASI I 63
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