scholarly journals The Process of Regenerative Heat Treatment of the Valve Chamber of the Steam Turbine

2019 ◽  
Vol 26 (3) ◽  
pp. 243-248
Author(s):  
Agata Wieczorska
Keyword(s):  
Steam Turbine ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Cast Steel ◽  
Degradation Process ◽  
Steam Turbines ◽  
Regenerative Heat ◽  
Plastic Properties ◽  
Term Operation ◽  
Dynamic Damage

Abstract Steel castings are often used in the construction of valve chambers of steam turbines. Stringent requirements are set due to the continuous operation of the material at elevated temperatures, in the order of 300°C to 600°C. The material of the valve chamber must be resistant to fatigue-creep changes as well as corrosion. This material must be also resistant to dynamic damage which occures when the turbine is starting and stopping. Dynamic damage is induced by a short-lasting but intense accumulation of localized stresses. The castings of the valve chambers of the steam turbine are usually made from the “three-component” type CrMoV-cast steel. Mentioned castings of the valve chamber are continuously subjected to high temperatures, either constant and periodically variable stresses. Due to this, the degradation process of material of the castings is taking place. It is caused by physicochemical processes such as: creep, relaxation, thermal fatigue, corrosion, erosion and changes in material properties, e.g. displacement of the critical point of brittleness. Finally, first cracks and deformations can be observed in the material during the operation. The art presents the process of revitalization technology of the steam turbine valve chamber which was subjected to long-term operation at high temperatures. The revitalization process is aimed at improving the plastic properties of the material and, as the result, extending its service life. The research presented in the article show that impact strength of the chamber material after revitalization is very high. Also the strength properties of the valve chamber, after revitalization, are high and in line with the requirements. The study show that the revitalization of the valve chamber was carried out correctly and restored the material to plastic deformation.

scholarly journals Effect of Long Term Service at Elevated Temperatures on Mechanical Properties of Manaurite XM Reformer Tubes

2016 ◽  
Vol 16 (4) ◽  
pp. 38-44
Author(s):  
J. Łabanowski ◽  
M. Jurkowski ◽  
M. Landowski
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Cast Steel ◽  
Internal Diameter ◽  
Term Operation ◽  
Static Tensile ◽  
Different Shapes ◽  
Reformer Tubes ◽  
The Relationship

Abstract Microstructure transformations occur in the Manaurite XM cast steel tubes during long-term operation in the reformer furnace were revealed and described. The relationship between mechanical properties, an increase of internal diameter of the tube and microstructure degradation is discussed. Static tensile test was performed on two types of samples with different shapes. It has been shown differences in the results of tests and an explanation of this phenomenon.

Microstructure and Mechanical Properties of G17CrMoV5-10 Cast Steel After Regenerative Heat Treatment

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Grzegorz Golański
Keyword(s):  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Strength Properties ◽  
Optimum Combination ◽  
Austenitizing Temperature ◽  
Energy Increase ◽  
Regenerative Heat ◽  
Term Operation

This paper presents the results of a research on the influence of regenerative heat treatment on microstructure and properties of a cast steel after long-term operation at the elevated temperature. The material under investigation was G17CrMoV5-10 cast steel taken out (in the form of a section) from an internal frame of steam turbine serviced for about 250,000 h. Performed research has proven that through the microstructure degradation long-term service contributes to an embrittlement and decrease in yield strength and tensile strength. The heat treatment, however, contributes to an impact energy increase regardless of the applied parameters (cooling rate). It has also been established that the optimum combination of strength properties and impact energy is ensured by the microstructure of high tempered bainite, whereas low strength properties and impact energy were obtained for the microstructure, which was slowly cooled from the austenitizing temperature, i.e., the ferritic-bainitic-ferritic microstructure.

scholarly journals Feasibility study of forced cooling of a supercritical steam turbine after a shut down of a power generating unit

2011 ◽  
Vol 32 (3) ◽  
pp. 201-214 ◽  
Author(s):  
Wojciech Kosman
Keyword(s):  
Steam Turbine ◽  
Feasibility Study ◽  
Steam Turbines ◽  
Term Operation ◽  
Safety Issues ◽  
Power Generating Unit ◽  
Cooling Conditions ◽  
Forced Cooling ◽  
User Interference

Feasibility study of forced cooling of a supercritical steam turbine after a shut down of a power generating unitTemperature related decrease of steam turbine components is one of the main transient processes that occur during a typical long-term operation. With a natural cooling (no user interference) it takes more than 14 days before the temperature of components reaches the level that allows to open and repair a turbine. It is then reasonable to apply a forced cooling in order to decrease the time between a shut-down of a power generating unit and a beginning of a repair. This paper presents the analysis of application of a forced cooling process to supercritical steam turbines. The main problems under the investigation are the safety issues of the process and the optimization of cooling conditions. The paper describes the safety restrictions and the optimization criteria. The process is analyzed in numerical simulations conducted for various cooling conditions.

Microstructure and Mechanical Properties of G17CrMoV5 – 10 Cast Steel After Regenerative Heat Treatment

2009 ◽  
Author(s):  
Grzegorz Golan´ski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Optimum Combination ◽  
Austenitizing Temperature ◽  
Regenerative Heat ◽  
Term Operation ◽  
Structure Degradation

The paper presents results of research on the influence of regenerative heat treatment on microstructure and properties of a cast steel after long term operation at the elevated temperature. The material under investigation was G17CrMoV5 – 10 cast steel taken out (in the form of a section) from an internal frame of steam turbine serviced for about 250 000 hours. Performed research has proved that, through the structure degradation, long-term service contributes to an increase of brittleness and decrease of mechanical properties — higher in the case of yield strength than tensile strength. The heat treatment, however, contributes to an increase of impact energy, regardless of the applied parameters. Is has also been proved that the optimum combination of mechanical properties and impact energy is ensured by the structure of high tempered bainite. Low mechanical properties and impact energy, however, were obtained for the structure which was slowly cooled from the austenitizing temperature, i.e. the ferritic – bainitic – ferritic structure.

scholarly journals Analysis of Possibility of Repairing Welding of Selected of the Steam Turbines

2019 ◽  
Vol 26 (4) ◽  
pp. 265-271
Author(s):  
Agata Wieczorska ◽  
Adrian Bujko
Keyword(s):  
Steam Turbine ◽  
Structural Changes ◽  
Cast Steel ◽  
Strength Properties ◽  
Steam Turbines ◽  
Repair Welding ◽  
Hardness Tests ◽  
Non Destructive ◽  
Steel Body

AbstractThe article presents the results of the study on the possibilities of repair by welding methods of exploitation steam turbine bodies. Two hull were investigation after a lifetime of more than 200.000 hours. Repair welding study were carried out on the L17HMF cast steel body in the immediately after exploitation condition, whereas the L21HMF cast steel body underwent a revitalization after the exploitation, and then the welding repair research were performed. On the material taken from the L17HMF cast steel hull, welding repairs were made by welding the previously cut four grooves measuring 200 mm 50 mm 50 mm, which were simulations of material defected. All samples were made in areas where maximum steam temperatures were operating. Welds were tested with destructive and non-destructive methods to determine their quality and define non-compliances detected. The L21HMF cast steel was subjected to a revitalization process, which consisted the hull in subjecting heat treatment in order to obtain favourable structural changes and improve the strength properties. Non-destructive examinations and hardness tests were carried out on the remedial weld, indicating the required quality of repairing remedial weld. Comparative study is aimed at demonstrating the main welding problems during the repair welding of exploitation steam turbine hulls.

EASTERN STAINLESS TYPE 310S

Alloy Digest ◽  
1984 ◽  
Vol 33 (8) ◽  
Keyword(s):  
High Temperatures ◽  
Elevated Temperatures ◽  
High Strength ◽  
Heat Treating ◽  
Oil Refining ◽  
Steel Company ◽  
Plant Equipment ◽  
The Many ◽  
Corrosion And Oxidation ◽  
Refining Equipment

Abstract EASTERN STAINLESS TYPE 310S has high resistance to corrosion and oxidation at high temperatures. It also has high strength at elevated temperatures. Thus it is especially suitable for service at high temperatures. It is very ductile and can be welded readily. Among the many applications for Type 310S, a few typical uses include annealing boxes, chemical plant equipment, fire box sheets, furnace linings, heat exchangers, oil-refining equipment, kiln linings and tube hangers. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-450. Producer or source: Eastern Stainless Steel Company.

Fault diagnosis method of peak-load-regulation steam turbine based on improved PCA-HKNN artificial neural network

2021 ◽  
pp. 1748006X2110105
Author(s):  
Yifan Wu ◽  
Wei Li ◽  
Deren Sheng ◽  
Jianhong Chen ◽  
Zitao Yu
Keyword(s):  
Neural Network ◽  
Fault Diagnosis ◽  
Steam Turbine ◽  
Power Plants ◽  
Peak Load ◽  
Clean Energy ◽  
Steam Turbines ◽  
Peak Shaving ◽  
Diagnosis Method ◽  
Load Regulation

Clean energy is now developing rapidly, especially in the United States, China, the Britain and the European Union. To ensure the stability of power production and consumption, and to give higher priority to clean energy, it is essential for large power plants to implement peak shaving operation, which means that even the 1000 MW steam turbines in large plants will undertake peak shaving tasks for a long period of time. However, with the peak load regulation, the steam turbines operating in low capacity may be much more likely to cause faults. In this paper, aiming at peak load shaving, a fault diagnosis method of steam turbine vibration has been presented. The major models, namely hierarchy-KNN model on the basis of improved principal component analysis (Improved PCA-HKNN) has been discussed in detail. Additionally, a new fault diagnosis method has been proposed. By applying the PCA improved by information entropy, the vibration and thermal original data are decomposed and classified into a finite number of characteristic parameters and factor matrices. For the peak shaving power plants, the peak load shaving state involving their methods of operation and results of vibration would be elaborated further. Combined with the data and the operation state, the HKNN model is established to carry out the fault diagnosis. Finally, the efficiency and reliability of the improved PCA-HKNN model is discussed. It’s indicated that compared with the traditional method, especially handling the large data, this model enhances the convergence speed and the anti-interference ability of the neural network, reduces the training time and diagnosis time by more than 50%, improving the reliability of the diagnosis from 76% to 97%.

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