Research On The Safe And Economic Optimization Of Steam Turbine In Startup

Electric power is China's economic lifeblood. Keeping the operation safety ofthe grid and the power stations smoothly is essential to support sustainable growth.High parameter, large capacity and automatization demands not only for electricalgrid but also for power generating units will become a tendency in order to increaseeconomics in 21st century. To ensure the stability of electrical grid running theAutomatic Generation Control (AGC) technology has to be improved. Based on anadvanced means between the electrical grid attemper system and the in-line controlsystem for power generating unit, AGC technology tends to launch into operationin China to balance the supply and the need of electric power, to improve electricenergy quality, to increase operation economics of electrical grid and to minimizelabor strength of employees.Main problem to carry AGC technology into execution in power plants is howto assess unit condition objectively and quantitively, especially, how to controloperation parameters of power plant unit correctly. On the basis of self-startupessential model established by GE, Siemens, etc., a theoretical framework ofoptimization model with the economic consideration based on the safe constraint ofsteam turbine has been presented in this paper.In aforementioned framework, based on heat transfer differential eguation forcylinder, one dimensional transient analytical solution along radial direction withrespect to the boundary conditions of outer adiabatic wall and inner wall with thirdtype temperature boundary is achieved, which can be used in on-line temperaturemonitoring system for the steam turbine casing. In order to demonstrate theexpansion ability of irregular finite sub-structure, a new characteristic value, calledexpansion characteristic temperature, is defined. And an appropriate algorithmwhich can be used to calculate the expansion of different parts is also proposed.Owing to such a definition, it is possible to evaluate expansion difference betweencasing and rotor.As a precondition for safety restriction of steam turbine, the factors influencing uniteconomics during startup are analyzed. A unified evaluation model considering fuelexpension, life consumption of equipment, labor cost, etc. is presented. Applying themodel a comprehensive evaluation to safety and economics of steam turbine in startupprocess can be carried out. Considering the restraint conditions, the unit start-upprocedures for 300MW steam turbine unit made in China is optimized.Using the analytical model presented by this paper, an actual evaluation systemto analyze temperature and axial deformation distributions, expansion differencesof each turbine stages, startup process optimization was developed and has beenapplied in operation management of a Shandong power plant. A obvious benefitduring the optimal startup process directed by the system has been observed.