Optimized turbine loadings

FIGURE 19.3. Optimized turbine loadings resulted in cost savings of 787,000 per year. 

Site composite curves can be used to represent the site heating and cooling requirements thermodynamically. This allows the analysis of thermal loads and levels on site. Using the models for steam turbines and gas turbines allows cogeneration targets for the site to be established. Steam levels can be optimized to minimize fuel consumption or maximize cogeneration. A cost trade-off needs to be carried out in order to establish the optimum trade-off between fuel requirements and cogeneration. 

This control system is both flexible and optimized FC-1 keeps the bypass flow to a minimum, while FC-3 reduces the LPS demand if it exceeds the work load on the turbine, and FC-3 makes more steam energy available to the turbine if the LPS demand is below the workload. 

The inlet pressure of 27 bar into the HP turbine was selected as a compromise. The largest pressure for closed cycle gas turbines with air was 40 bar at that time. Conditions for a nuclear heated plant provided with a helium-turbine were foreseen as about 60 bar, a helium-temperature of 850 C and a plant capacity of 300 MWe. The low pressure turbine was selected to deliver power at a frequency of 50 Hz or 3000 rpm and is connected by a gear arrangement to the high pressure turbine shaft that rotates at 5500 rpm. It has dimensions and stress loadings for the rotor shaft for the blades and for the mrbine housing which are very similar to those of a 300 MW helium-turbine plant considered at the time as the reference size. In addition to optimization requirements a reason for the limitation of the primary pressure was the permissible stresses for the material of the mbes of the fossil-fired heater. 

Mechanical design of the turbine blade root and rotor steeple attachments uses optimized contour to significantly reduce operational stresses. Steam flow to the high-pressure turbine is controlled by two floor-mounted steam chests. Each contains two throttle/stop valve assemblies, and two load-governing valves. 

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