Investigation of Steam Turbine Blades Damage and Reliability in a Power Plant

2019 ◽  
Vol 799 ◽  
pp. 89-94
Author(s):  
Artjom Molodtsov ◽  
Andrei Dedov ◽  
Ivan Klevtsov ◽  
Lembit Kommel ◽  
Toomas Lausmaa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Power Plant ◽  
Steam Turbine ◽  
Experimental Testing ◽  
Turbine Blades ◽  
Microstructural Analysis ◽  
Technical Requirements ◽  
Study Results ◽  
Electron Microscopes

This work presents an experimental case study of 200 MW low-pressure steam turbine rotor blades damage after 310 thousand hours of operation and 404 start-ups on the power plant. Damaged blade material was analysed by experimental testing of mechanical properties as well as crack initiation and microstructure in the damaged area by using optical and scanning electron microscopes, and investigation of chemical composition by the SEM-EDS method. Results of the investigation show that the material was die forged martensitic steel 20Cr13. The mechanical properties of the blade steel were in accordance with standard technical requirements for new material. The cross-sections of damaged and undamaged blades were investigated and compared. It was found that thickness of damaged blades was significantly less than undamaged ones. SEM-EDS analysis has shown the presence of brass fragment on the surface of one damaged blade. The microstructural analysis has shown that one of the cracks was initiated due to impact of brass fragment. Based on the given case study results it is concluded that the reason of the blade damage was a combination of at least two factors: accelerated high cycle fatigue due to increased stresses caused by excessive vibration of damaged blades with lower thickness and impact of brass fragment against blades.

Study of wear mechanism of contact surfaces of steam turbine blades made of titanium VT6 alloy

2021 ◽  
pp. 81-89
Author(s):  
A.M. Zolotov ◽  
M.O. Smirnov ◽  
T.A. Chizhik
Keyword(s):  
Mechanical Properties ◽  
Steam Turbine ◽  
Wear Mechanism ◽  
Turbine Blades ◽  
Microstructural Analysis ◽  
X Ray ◽  
Different Types ◽  
Steam Turbine Blades ◽  
Contact Surfaces

The contact surfaces of the banding shelves of adjacent steam turbine blades made of titanium VT6 alloy after operation are studied by fractography, micro-X-ray and microstructural analysis and determination of mechanical properties. The different types of destruction of the contact surfaces are analyzed and explained. It is shown that the reason for intensive abrasion of the turbine blades' binding meshes is violation of the welding mode in the station conditions.

scholarly journals Twisting of the Tail Rotor Shaft - A Case Study

2018 ◽  
Vol 778 ◽  
pp. 28-32
Author(s):  
Muhammad Shahzad ◽  
Tanveer Manzoor ◽  
Qanita Tayyaba ◽  
Ammad Hussain Qureshi
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Strain ◽  
Microstructural Analysis ◽  
Sem Images ◽  
Rotor Shaft ◽  
Ansys Simulation ◽  
Strain Rate Loading ◽  
Rule Out

Presented results report the findings of a case study carried out to determine the possible factors that lead to the twisting of tail rotor shaft. The structural materials of the shaft was evaluated in terms of microstructural analysis and mechanical properties to rule out any material fault. The SEM images showed that the localized fractures at twist ends occurred without any significant plastic deformation. Moreover, there was no evidence of fatigue. Such behavior suggests that twist occurred under impact / high strain rate loading. Such loading conditions are not possible during the event to ground hitting. The Ansys simulation confirmed that the observed twisting can increase the stress at localized point in excess of UTS and cause fracture.

Brazed coatings for steam turbine blades: impact of the tape architecture and composition on mechanical properties

2020 ◽  
Vol 111 (11) ◽  
pp. 916-922
Author(s):  
K. Bobzin ◽  
W. Wietheger ◽  
J. Hebing ◽  
L. Gerdt ◽  
H. Krappitz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Steam Turbine ◽  
Volume Fraction ◽  
Steel Substrate ◽  
Turbine Blades ◽  
Surface Hardness ◽  
Three Point Bending ◽  
Wear And Corrosion ◽  
Steam Turbine Blades ◽  
Positive Effect

Abstract Ni-based brazing coatings with tungsten or chromium carbides are used for wear and corrosion protection in various applications. Steam turbine blades especially present a highly stressed application in which in particular the resistance to erosion and corrosion is essential. Therefore, novel tape architectures of brazed coatings have been developed and investigated within this study. In contrast to the use of powders, the application by means of tapes offers a high potential with regard to later use in industry due to the reproducible handling and automation. In this work, different coating systems were successfully deposited by means of vacuum brazing on X12CrNiMo-12 steel substrate. In order to achieve a sufficient fracture toughness of the coatings, pure nickel powder was added to the tapes. The influence of this additive on the mechanical properties was analyzed by means of three-point bending tests. A positive effect has been observed when adding a volume fraction of φ(Ni) = 25% of nickel, increasing the flexural strength up to σf = 580 MPa. Furthermore, the surface hardness of the coating has been analyzed depending on coating architecture and post-deposition treatment by grinding.

THE MICROSTRUCTURAL ANALYSIS OF THE EFFECT OF FIC ON GAS TURBINE BLADES

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4135-4140 ◽  
Author(s):  
HYUNG-ICK KIM ◽  
YONG HUH ◽  
HONG-SUN PARK ◽  
CHANG-SUNG SEOK ◽  
MOON-YOUNG KIM
Keyword(s):  
Mechanical Properties ◽  
Gas Turbine ◽  
Operation Mode ◽  
Turbine Blades ◽  
Microstructural Analysis ◽  
Repair Process ◽  
Optical Microscope ◽  
Important Indicator ◽  
Nickel Based Superalloy ◽  
Phase Coarsening

Advancements in superalloys permit hot gas path components to operate for many thousands of hours under severe centrifugal, thermal and vibratory stresses. The blade of a gas turbine must withstand the most severe combination of temperature, stress, and environment. After a certain period of operation, the blade is damaged by the turbine operation mode. To recover the similar initial mechanical properties, the blade of nickel-based superalloy component undergoes a replacement repair process. A fluoride ion cleaning (FIC) process is used to assist in the successful welding repair of nickel-based superalloy components. This work is to study the FIC influence on a gas turbine blade that was serviced 25,748 equivalent operating hour (EOH) after first overhaul. The blades, including the fractured regions were obtained from a plant. The conditions of blade samples were observed by optical microscope and SEM, and the chemical composition of the flaws in the blade was investigated by EDS. γ′ phase morphology is also an important indicator of the mechanical properties of blades at the high temperatures. The blade condition was examined from morphology and size of the γ′ phase, because the γ′ phase coarsening rate depends largely on the exposure time and temperature.

Case study: Paper mill power plant optimization—balancing steam venting with mill demand

TAPPI Journal ◽  
2020 ◽  
Vol 19 (6) ◽  
pp. 317-321
Author(s):  
RICARDO B. SANTOS ◽  
PETER W. HART
Keyword(s):  
Power Plant ◽  
Steam Turbine ◽  
Operating Cost ◽  
Production Costs ◽  
Electricity Production ◽  
Financial Benefit ◽  
Pressure Steam ◽  
Plant Optimization ◽  
Steam Production

Most Power departments are tasked with generating steam to support mill wide operations, gener-ate electricity, and reduce operating costs. To accomplish these tasks, power boilers generate high pressure steam that is reduced to intermediate and low pressures for process utilization in the mill by means of steam turbine generator extraction or pressure reducing valves. The most economical method to reduce steam pressure is the use of steam turbine generators, as electricity is generated from the steam when it is reduced in pressure. Electricity that is produced by these generators provides a substantial financial benefit and helps offset overall operational costs. To achieve tangible financial gains, the mill must evaluate the overall cost of steam production and the price of electricity. The current work provides a case study of power plant optimization that evaluated electricity production and steam production costs balanced with mill steam demand. Process and cost optimization led to a significant reduction in low pressure steam venting, resulting in reduced fuel consumption and reduced operating cost.

scholarly journals Reverse engineering methodology as a way of steam turbine blades designing for Loviisa Nuclear Power

2019 ◽  
Vol 137 ◽  
pp. 01002
Author(s):  
Radosław Bondyra ◽  
Krzysztof Dominiczak ◽  
Jacek Matuszak
Keyword(s):  
Power Plant ◽  
Reverse Engineering ◽  
Steam Turbine ◽  
Nuclear Power ◽  
Turbine Blades ◽  
Selection Criterion ◽  
Spare Parts ◽  
Cost Competitiveness ◽  
Last Stage ◽  
Lp Turbine

This article concerns a reverse engineering-based design process of last stage blade (LSB) for other original equipment manufacturer (oOEM). For Loviisa Power Plant (Finland) GE designed and delivered a set of oOEM LSBs to be fit into existing low pressure (LP) turbine module steam path. Although cost competitiveness is a one of major selection criterion for steam turbine spare parts components supplier, diversification of suppliers is also a strategic for power plant owner. Considered here is a process of reengineering of oOEM LSB and all relevant challenges related to this process especially management of geometry deviations between reverse-engineered and oOEM blade. In this article, there are a design steps described taken to qualify reverse-engineered design. Moreover, a manufacturing process of the LSB is shown.

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