Research On Improving The Peak Shaving Capacity Of HP-IP Modules In 660MW Steam Turbine

With the great changes of energy and social power consumption structure,the difference between peak load and valley load is becoming larger and larger.Meanwhile,the increase in the proportion of clean energy generation has brought a severe test to the peak shaving and grid absorption,causing economic losses and waste of social resources,which requires the key equipment of the thermal power units to have the ability to start and change load more quickly.It is of great significance to optimize the process of startup and load change,increase the response speed under the premise of satisfying the operational safety,which has a positive effect on improving the flexibility of large-capacity thermal power units to participate in peak shaving and solving the absorption problem of new energy power generation.This paper took the high and medium pressure modules of an ultra-supercritical 660 MW steam turbine as the research object.A two-dimensional axisymmetric finite element model of the rotor and a three-dimensional finite element model of the inner cylinder were established with suitable meshing methods.Boundary conditions were reasonably assumed and calculated.Workbench finite element software was used to calculate the changes of the temperature and stress fields of the high and medium pressure rotor and inner cylinder under the original cold startup process.Six high stress regions(three each for the rotor and inner cylinder)during the startup process were selected as stress monitoring points during numerical calculation.Combined with the operation rules of the steam turbine,the temperature of each monitoring point and the stress of the inner cylinder,the adjustment range of the warm-up time and the load-up rate was determined.Four comparison schemes were initially drawn up for finite element calculation.The temperature and stress fields of different schemes were analyzed,and the change law of stress levels of the rotor and inner cylinder with warm-up time and load-up rate were obtained.Based on above results,for further reducing the stress levels of the rotor and inner cylinder,the warm-up time and load-up rate were adjusted again.Through a series of numerical tests,the final optimization plan was determined.The results showed that the stress level of each monitoring point had no obvious change compared with the original cold startup plan,but the startup time was shortened by nearly 17%.Finally,the stress changes of the high and medium pressure rotor and inner cylinder during load change for peak shaving were also analyzed and optimization suggestions were given about load change rate.These jobs made the time of load change been effectively shortened while the current life loss of the unit was almost unchanged,which improved the maneuverability of the large thermal power units to participate in peak shaving.