Turbines, steam deterioration

It was found that estimated steam rates for current conditions were 10% higher on average than the design performance. The reason was because the turbine performance deteriorates over time. This was reflected by a hotter outlet temperature. Therefore, the steam rates for the boiler drivers and CT-1601 were adjusted to 210 (vs. 183) and 90 (vs. 71) klb/h, respeetively. 

The gas that accumulates inside the surface condenser is called the noncondensable load to the steam jets. Some of the noncondensable load consists of C02 accidentally produced when the boiler feedwater is vaporized into steam. Air leaks through piping flanges and valves are other sources of noncondensable vapors. But the largest source of noncondensable vapors is often air drawn into the turbine case, through the shaft s mechanical seals. To minimize this source of leaks, 2 or 3 psig of steam pressure is ordinarily maintained around the seals. However, as the turbine s shaft seals deteriorate, air in-leakage problems can overwhelm the jet capacity. This will cause a loss of vacuum in the surface condenser. 

A turbine produces 60 MWh of electricity per year. The annual average cost of the steam is 0.0175/ kWh of exergy (fuel). The total cost of the unit (fixed capital investment and operating costs) is 2.5 X 10. If the turbine exergetic efficiency decreases from 90% to 80% after deterioration of the tmbine with use, evaluate the change of the unit cost of electricity. 

In the 1950s, the idea of using supercritical water (SCW) appeared to be rather attractive for steam generators/turbines in the thermal power industry. The objective was to increase the total thermal efficiency of coal-fired thermal power plants. At supercritical pressures, there is no liquid—vapor phase transition therefore, there is no such phenomenon as critical heat flux or dryout. It is only within a certain range of parameters that deteriorated heat transfer may occur. Work in this area was mainly... 

Metallurgical recovery, refurbishment (see Metallurgy) Steam-Turbine Deterioration and Diagnosis Performance recovery... 

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