Neural Modelling of Steam Turbine Control Stage

2020 ◽  
pp. 117-128
Author(s):  
Jerzy Głuch ◽  
Marta Drosińska-Komor
Keyword(s):  
Steam Turbine ◽  
Control Stage ◽  
Neural Modelling

Reduction of Solid-Particle Erosion on the Control-Stage Nozzle of a Steam Turbine through Improved End-Wall Contouring

2010 ◽  
Vol 224 (10) ◽  
pp. 2199-2210 ◽  
Author(s):  
S-S Wang ◽  
J-R Mao ◽  
G-W Liu ◽  
Z-P Feng
Keyword(s):  
Weight Loss ◽  
Steam Turbine ◽  
Solid Particle ◽  
Optimization Method ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Control Stage ◽  
Contraction Ratio ◽  
Starting Point ◽  
End Wall

The iron oxide scales exfoliated from the inner wall of a boiler tube and a main steam pipe is known to cause solid-particle erosion on the control-stage nozzle. A combined experimental and numerical investigation was conducted to explore the optimization method of end-wall contouring for reducing the nozzle's erosion damage most effectively. The results indicate that increasing the end-wall contraction ratio and (or) decreasing the distance between the starting point of end-wall contouring and the trailing edge can significantly reduce the erosion-induced weight-loss of the nozzle, and can slightly improve the nozzle efficiency, irrespective of the variation in the particles size distribution and the aerodynamic parameters of a steam turbine. A main reason of erosion reduction is that the movement of loading towards the rear of the nozzle cascade caused by these contoured end walls has reduced the incident velocity of particles. In this study, the weight-loss of the nozzle was reduced by 40—50 per cent, and the nozzle efficiency was improved by 0.4—0.5 per cent by improving the end-wall contouring of the nozzle according to the methods mentioned above.

The influence of nozzle chamber structure and partial-arc admission on the erosion characteristics of solid particles in the control stage of a supercritical steam turbine

Energy ◽  
2015 ◽  
Vol 82 ◽  
pp. 341-352 ◽  
Author(s):  
Liu-xi Cai ◽  
Shun-sen Wang ◽  
Jing-ru Mao ◽  
Juan Di ◽  
Zhen-ping Feng
Keyword(s):  
Steam Turbine ◽  
Solid Particles ◽  
Control Stage

Rotordynamic Stability Under Partial Admission Conditions in a Large Power Steam Turbine

2009 ◽  
Author(s):  
Lin Gao ◽  
Yiping Dai ◽  
Zhiqiang Wang ◽  
Yatao Xu ◽  
Qingzhong Ma
Keyword(s):  
Steam Turbine ◽  
Fluid Model ◽  
Rotor System ◽  
System Stability ◽  
Steam Turbines ◽  
Large Power ◽  
Control Stage ◽  
Partial Admission ◽  
The Stability ◽  
Load Conditions

At present, the majority of power steam turbines operate under part-load conditions during most of their working time in accordance with the fluctuation of power supply. The load governing method may cause partial admission in control stage and even some pressure stages, which impacts much on the stability of the rotor system. In this paper, CFD and FEM method were used to analyze the effect of partial admission on rotor system stability. A new approach is proposed to simplify the 3D fluid model for a partial admission control stage. Rotordynamic analysis was carried out to test the stability of the HP rotor of a 600 MW steam turbine under different load conditions. 13 different governing modes on the rotor stability were conducted and data were analyzed. It is found that rotor stability varies significantly with different governing modes and mass flow rates, which is consistent with the operation. Asymmetric fluid forces resulted from partial admission cause a fluctuation of the dynamic characteristics of the HP bearings, which consequently affect the stability of the rotor system. One of the nozzle governing modes in which the diagonal valves open firstly is demonstrated as the optimal mode with the maximum system stability. The optimization has been applied to 16 power generation units in China and result in improved rotor stabilities.

Influence of Oxide Particle Size on the Erosion of the Control Stage Nozzle in a Supercritical Steam Turbine

2013 ◽  
Author(s):  
Liu-xi Cai ◽  
Shun-sen Wang ◽  
Lei Zhang ◽  
Jing-ru Mao ◽  
Zhen-ping Feng ◽  
...  
Keyword(s):  
Particle Size ◽  
Steam Turbine ◽  
Erosion Resistance ◽  
Size Range ◽  
Small Particles ◽  
Suction Surface ◽  
Erosion Damage ◽  
Pressure Surface ◽  
Control Stage ◽  
Large Particles

Reducing the solid particle erosion (SPE) of blades is one of the most important problems for high-parameter steam turbine. Based on the erosion rate models and the particle rebound models of blade materials obtained through the accelerated erosion test under high temperature, a lot of three dimension numerical simulations were conducted in this paper. The influence of particle size on the impingement point distribution on the nozzle surface and the erosion characteristics of control stage nozzle in a supercritical steam turbine were analyzed quantitatively. The size range of the oxide scale particles participating in the erosion damage were extended to 500μm, and some special anti-erosion measures corresponding to different size particles were proposed to reduce the erosion of nozzle. Results show that the erosion of pressure surface in the trailing edge of nozzle is mainly from the high-intensity impingement of particles smaller than 160μm, especially those with the size range from 20μm to 60μm. For the impingement of these small particles, optimizing the profile and cascade structure as well as coating the hard coating on the surface of nozzle can improve the erosion resistance of nozzle. However, these small particles do not impinge the nozzle trailing edge suction surface. The severe erosion damage of suction surface of nozzle was from the impingement again of the particles with the size range from 200μm to 500μm after rebounding from nozzle pressure surface. It is very difficult to resist the erosion damage of these large particles for the hard coating, and separating large particles from main steam before entering the nozzle chamber should be a good choice for improving the erosion resistance of turbine. These studies will provide a technical basis for selecting anti-erosion measures of control stage nozzle.

Rotor Dynamic Analysis on Partial Admission Control Stage in a Large Power Steam Turbine

2010 ◽  
Author(s):  
Lin Gao ◽  
Yiping Dai
Keyword(s):  
Steam Turbine ◽  
Phase Angle ◽  
Low Frequency ◽  
Deep Understanding ◽  
Labyrinth Seal ◽  
Steam Turbines ◽  
Large Power ◽  
Stiffness Coefficients ◽  
Control Stage ◽  
Partial Admission

Partial admission is used widely for steam turbines to match their output power to the load demand. The occurrences or thresholds of most self-induced low-frequency vibrations are under partial admission conditions. But the destabilizing forces which cause rotor instability are seldom investigated under partial admission conditions especially for large power steam turbines. Full 3D CFD model is built for the control stage of a 600 MW steam turbine applying commercial codes. N-S equations are solved to investigate the flow fields in the control stage including all the blade passages and the labyrinth seal over the shroud. Interesting flow distributions are observed for the seal spaces at partial admission conditions. A correction formula is presented for partial admission labyrinth seal based on the classical one and a method is discussed for the estimation of partial-admission phase-angle-dependent stiffness coefficients. The destabilizing forces acting on the rotor system are calculated for different eccentricity angles and are compared with those under the concentric condition. The stiffness coefficients are solved under typical partial admission conditions. They are found to change dramatically with the phase angle. The results may be helpful for a deep understanding of the low-frequency variation problems of large power steam turbines under partial admission conditions.

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