Abstract
Turbine and plant heat rates obtainable in large modern power plants are compared over a wide range of the pressure-temperature-cycle realm. These results were estimated from heat balances based on typical expansion lines for 30,000-kw turbines, which size was deemed sufficiently representative to draw rather general conclusions regarding large units. Cost estimates are not included, but the results are given in a form readily adaptable to the needs of those making economic comparisons. To this end, plant heat rates are given for estimating the rate of use of fuel, and turbine heat rates with supplementary data for estimating the size, and hence the cost, of the various equipment in a plant. The difference between turbine and plant heat rates allows for auxiliary power in proportion to the cycle requirements, and for miscellaneous losses sufficient to give the expected annual average value of the plant heat rates. While the computations are purposely fitted to a particular type of turbine and plant, the results apply approximately to most of the modern central stations. Comparisons of the thermal efficiencies of practical cycles with corresponding Carnot efficiencies are used to point out the best direction for future efforts. It is concluded that regenerative-feed-heating plants with the highest practicable initial temperature offer the greatest promise, both for immediate use and for future development.
