Experimental Investigation on the Solid Particle Erosion in the Control Stage Nozzles of Steam Turbine

2007 ◽  
Author(s):  
Shunsen Wang ◽  
Guanwei Liu ◽  
Jingru Mao ◽  
Zhenping Feng
Keyword(s):  
Life Cycle ◽  
Steam Turbine ◽  
Solid Particle ◽  
Erosion Rate ◽  
Impact Angle ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Control Stage ◽  
Profile Characteristic ◽  
The Impact

This study is concerned with experiments for the relation of solid particle erosion (SPE) and the nozzle profiles. The exfoliated scale from boiler tubing results in hard particles that erode steam turbine components, especially on the control stage nozzles of high parameters turbine. To characterize SPE, solid particle trajectory is measured using particle image velocimetry (PIV) and its relation with the erosion rate of the nozzle surfaces is correlated. In addition, erosion characteristic of nozzle material is investigated by experiments and results reveal that the erosion rate is directly proportional to the impacting velocity of particles with the power of 2.31 and the maximum erosion rate is taken place at the impact angle of 20–25 degree. Furthermore, 0.5% increase in the erosion rate for every one degree of steam temperature rise is observed in the range of 839K∼883K. The erosion rate of front-loaded nozzle A is 2∼3 times higher than that of conventional design nozzle B. The life cycle of nozzle is determined by the erosion of outlet edge, and the life of nozzle B is about 5 times as long as the life of nozzle A. Based on the relation of erosion rate and nozzle profile characteristic, it can be inferred that a aft-loaded nozzle with a contoured endwall substituting a planar endwall may outperform over other nozzle profiles in anti-SPE, prolonging the life cycle of the nozzle.

Research on Solid Particle Erosion Behaviors of TC4 Alloy at Different Erosion Angles

2014 ◽  
Vol 1049-1050 ◽  
pp. 167-170
Author(s):  
Bao Hui Guo
Keyword(s):  
Solid Particle ◽  
Erosion Rate ◽  
Impact Angle ◽  
Large Impact ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Erosion Mechanism ◽  
Tc4 Alloy ◽  
Impact Angles ◽  
The Impact

The solid particle erosion behaviors of TC4 Alloy were studied at different erosion angles. The results show that the erosion rate of TC4 alloy at impact angle 30o was higher than those at the impact angles of both 60o and 90o. At low impact angle, the erosion mechanism could be concluded as grinding erosion and furrow erosion. However, the erosion mechanism could be fatigue erosion at large impact angle.

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.

Numerical investigation of the solid particle erosion rate in a steam turbine nozzle

2007 ◽  
Vol 27 (14-15) ◽  
pp. 2394-2403 ◽  
Author(s):  
Alfonso Campos-Amezcua ◽  
Armando Gallegos-Muñoz ◽  
C. Alejandro Romero ◽  
Zdzislaw Mazur-Czerwiec ◽  
Rafael Campos-Amezcua
Keyword(s):  
Steam Turbine ◽  
Numerical Investigation ◽  
Solid Particle ◽  
Erosion Rate ◽  
Solid Particle Erosion ◽  
Particle Erosion

The Effects of Surface Treatments on Solid Particle Erosion of 12Cr Steels for USC Power Plants

2006 ◽  
Vol 118 ◽  
pp. 201-208
Author(s):  
Kee Won Urm ◽  
Sun Ho Lee ◽  
J.W. Lee ◽  
E.Y. Lee
Keyword(s):  
Solid Particle ◽  
Impact Angle ◽  
Surface Treatments ◽  
Solid Particles ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Hvof Spray ◽  
Bare Steel ◽  
The Impact ◽  
Turbine Bucket

12Cr steels have been applied on the turbine bucket and nozzle partition materials for the ultra super critical (USC) coal-fired power plant. Turbine bucket and nozzle materials are damaged by the solid particles within USC steam conditions. Therefore, they have been protected by the surface treatments such as ion nitriding, boriding and chrome carbide high velocity oxygen fuel (HVOF) spray coating. In this study, the surface treatment effects on the solid particle erosion (SPE) characteristic of 12Cr steels were examined in the temperature range of 540 to 620°C and the mechanisms of surface damage are investigated. The SPE of 12Cr steel originated from micro cutting, whereas, that of boriding and chrome carbide HVOF spray originated from the repeated collision, crack initiation and propagation. In case of 12Cr bare steel, the erosion of soft materials occurred in the impact angle range of 30° to 60° at test temperatures. The SPE resistances of boride and HVOF treated steels in the impact angle range of 30° to 60° at 593°C and 621°C were much higher than those of 12Cr bare steel.

scholarly journals Effect of Silicon Addition on High-Temperature Solid Particle Erosion-Wear Behaviour of Mullite-SiC Composite Refractories Prepared by Nitriding Reactive

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaochao Li ◽  
Shusen Chen ◽  
Zhaohui Huang ◽  
Minghao Fang ◽  
Yan’gai Liu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Solid Particle ◽  
Elevated Temperatures ◽  
Silicon Powder ◽  
Wear Behaviour ◽  
Solid Particle Erosion ◽  
Erosion Wear ◽  
Particle Erosion ◽  
Powder Addition ◽  
The Impact

Solid particle erosion-wear experiments on as-prepared mullite-SiC composite refractories by nitriding reactive sintering were performed at elevated temperatures, using sharp black SiC abrasive particles at an impact speed of 50 m/s and the impact angle of 90° in the air atmosphere. The effects of silicon powder addition and erosion temperature on the erosion-wear resistance of mullite-SiC composite refractories were studied. The test results reveal that Si powders caused nitriding reaction to formβ-sialon whiskers in the matrix of mullite-SiC composite refractories. The erosion-wear resistance of mullite-SiC composite refractories was improved with the increase of silicon powder addition and erosion temperature, and the minimum volume erosion rate was under the condition of 12% silicon added and a temperature of 1400°C. The major erosion-wear mechanisms of mullite-SiC composite refractories were brittle erosion at the erosion temperature from room temperature to 1000°C and then plastic deformation from 1200°C to 1400°C.

Representative volume element-based simulation of multiple solid particles erosion of a compressor blade considering temperature effect

2019 ◽  
Vol 234 (8) ◽  
pp. 1173-1184
Author(s):  
Bijan Mohammadi ◽  
AmirSajjad Khoddami
Keyword(s):  
Finite Element ◽  
Solid Particle ◽  
Representative Volume Element ◽  
Erosion Rate ◽  
Compressor Blade ◽  
Volume Element ◽  
Solid Particles ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Representative Volume

Solid particle erosion is one of the main failure mechanisms of a compressor blade. Thus, characterization of this damage mode is very important in life assessment of the compressor. Since experimental study of solid particle erosion needs special methods and equipment, it is necessary to develop erosion computer models. This study presents a coupled temperature–displacement finite element model to investigate damage of a compressor blade due to multiple solid particles erosion. To decrease the computational cost, a representative volume element technique is introduced to simulate simultaneous impact of multiple particles. Blade has been made of Ti-6Al-4V, a ductile titanium-based alloy, which is impacted by alumina particles. Erosion finite element modeling is assumed as a micro-scale impact problem and Johnson–Cook constitutive equations are used to describe Ti-6Al-4V erosive behavior. In regard to a wide variation range in thermal conditions all over the compressor, it is divided into three parts (first stages, middle stages, and last stages) in which each part has an average temperature. Effective parameters on erosive behavior of the blade alloy, such as impact angle, particles velocity, and particles size are studied in these three temperatures. Results show that middle stages are the most critical sites of the compressor in terms of erosion damage. An exponential relation is observed between erosion rate and particles velocity. The dependency of erosion rate on size of particles at high temperatures is indispensable.

Some Aspects of Steam Turbine Valves: Materials, Operations and Maintenance

2013 ◽  
Author(s):  
Kuda R. Mutama
Keyword(s):  
Power Plant ◽  
Steam Turbine ◽  
Solid Particle ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Pull Out ◽  
Essential Components ◽  
The World ◽  
Maintenance Cycle ◽  
Main Steam

Steam turbine valves are the most essential components of modern steam turbines from an operation, performance, reliability and safety aspects of a modern power plant. Current designs are pushing the operational envelope and it is not uncommon for large ultracritical plants to run on pressures exceeding 4500 psi and 1200 °F. These conditions are not only challenging for materials of construction for turbines and boilers but also for main steam turbine valves. The tendency of materials to oxidize at these temperatures is all too common causing problems for valve heads, stems, discs, bushings and seats. OEMs around the world are pushing to develop valve components with 9–12% Cr martensitic steels and nickel based alloys which offer better creep strength at elevated temperatures. For existing power plants at temperatures of a 1000 to 1050 °F range there is a push to retrofit valve components with Incolloy 901 type, Inconel 718 and Stellite alloys. Scale build up in traditional alloys happens too quickly for the usual two year maintenance cycle. The application of better alloys for steam turbine valves makes it possible to increase the maintenance cycle from two to four or even six years, while increasing the operational reliability of the valve. Elimination of main steam valve failures removes risks of turbine overspeed events and increases plant availability. Solid particle erosion is not forgiving on valve parts such as stems, discs and valve seats and over a period of time, excessive wear causes the valve to be rendered unsafe to continued service. Nitrided materials and chrome-carbide-coated materials are much harder than the stem base material; and to slow down wear, a nitriding process is used to develop a thin, hard, wear-resistant surface. Some of the material often used for Stellite liners are Nitralloy 135M, 410 SS, 422 SS Nitrided, Incolloy 901 Nitrided, 347 SS, 13Cr-13Ni-10Co-3Nb-2.5W-2Mo. Different OEMs use a variety of alloys for valve seats, discs and stems. Antigalling characteristics are particularly favorable. Valve casings are cast materials and usually specifications include the ASTM A217 and ASTM A356. The ASTM A217 cast steels are typically, 1.25Cr-0.5Mo Grade WC6 and the 2.25Cr-1Mo Grade WC9 materials. Some of the problems experienced with steam turbine valves, are sticking to the valve seat requiring excessive pull-out force, wear of the seat surface, valves not closing properly due to oxidation build up, Stellite weld cracking, cutting or gouging due to solid particle erosion. The material presented in this paper is of interest to fossil power plant personnel experiencing challenges on valve performance and maintenance. The paper looks at all aspects of steam turbine valves as far as current trends in valve material, operation and maintenance and lastly, looks at recent occurrences of valve failures leading to steam turbine overspeed catastrophic failures around the world.

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