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.

Modern Reaction HP/IP Turbine Technology Advances and Experiences

2005 ◽  
Author(s):  
Paul Hurd ◽  
Frank Truckenmueller ◽  
Norbert Thamm ◽  
Helmut Pollak ◽  
Matthias Neef ◽  
...  
Keyword(s):  
Steam Turbine ◽  
High Efficiency ◽  
Combined Cycle ◽  
Advanced Technology ◽  
Advanced Materials ◽  
Operational Experience ◽  
Steam Turbines ◽  
Opposed Flow ◽  
Coal Market

Modern steam turbines of the author’s company are based on advanced technology such as high efficiency seals, 3D blading, single inner cylinders, and advanced materials. These technologies result in a compact opposed-flow HP/IP combined cylinder design with high long-term efficiency, reliability, and availability. This paper will illustrate the features, benefits, and operational experience of large steam turbines with advanced technologies using an opposed-flow HP/IP cylinder. The paper will also address the relative performance of this type of steam turbine against its predecessors. Specific examples will be examined: 350 MW fossil units in the Asian market, a typical 250 MW combined cycle steam turbine in the American market, a 700 MW three-cylinder class design for conventional steam plants developed for the global coal market, and a 600 MW steam turbine upgrade.

Preparation of Long Term Operation in Dukovany NPP, Czech Republic

2009 ◽  
Author(s):  
Robert Krivanek
Keyword(s):  
Czech Republic ◽  
Risk Analysis ◽  
Feasibility Study ◽  
Regulatory Body ◽  
Original Design ◽  
Term Operation ◽  
Safety Aspects ◽  
Program Strategy ◽  
The Status

Dukovany NPP has 4 units with VVER440/213 type reactors and is in its 24th year of operation. Operational permission is valid for 30 years. Since 2004, NPP has started to prepare a LTO program which includes: • a detailed feasibility study, • an evaluation of safety aspects of LTO, • the preparation of a long-term modernization plan, • risk analysis etc. This program is now approved by company management and by the Czech regulatory body. It should enable operation up to 60 years. The article gives information about the status of the NPP Dukovany long-term operation (LTO) preparation. It gives an overview of results of the prepared LTO Assurance Program, Strategy of the NPP Dukovany LTO, along with risk analysis. The article details the procedure for the NPP Dukovany preparation for operation beyond the limits of original design lifetime, and ensuing planned stages.

Influence of Creep on Low-Cycle Fatigue Life Assessment of Ultra-Supercritical Steam Turbine Rotor

2014 ◽  
Author(s):  
W. Z. Wang ◽  
J. H. Zhang ◽  
H. F. Liu ◽  
Y. Z. Liu
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Turbine Rotor ◽  
High Temperature Creep ◽  
Cycle Fatigue ◽  
Term Operation ◽  
Start Up

Linear damage method is widely used to calculate low-cycle fatigue damage of turbine rotor in the long-term operation without fully considering the interaction between creep and low cycle fatigue. However, with the increase of steam turbine pressure and temperature, the influence of high-temperature creep on the strain distribution of turbine rotor becomes significant. Accordingly, the strain for each start-up or shut-down process is different. In the present study, the stress and strain during 21 iterations of continuous start-up, running and shut-down processes was numerically investigated by using the finite element analysis. The influence of high-temperature creep on low cycle fatigue was analyzed in terms of equivalent strain, Mises stress and low cycle fatigue damage. The results demonstrated that the life consumption of turbine rotor due to low cycle fatigue in the long-term operation of startup, running and shutdown should be determined from the full-time coverage of the load of turbine rotor.

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.

Application of the Multi-Axial Creep Failure Method on Double Reheat Thermodynamic Cycle Turbine

2013 ◽  
Author(s):  
Gang Chen ◽  
Puning Jiang ◽  
Yuxiang Wang ◽  
Zhenzhen Hao
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Life Prediction ◽  
Thermodynamic Cycle ◽  
Critical Issue ◽  
Design Criteria ◽  
Creep Failure ◽  
Term Operation ◽  
High Temperature Components

With the development of higher efficiency and lower consumption plants, higher steam parameters to 600/620/620°C and 33/10.6/3.5MPa and double reheat thermodynamic cycle system are adopted for the power plant. Thus, it is believed that the safety of high temperature components in the steam turbine system is a critical issue that could not be circumvented in the period of modern industrial development. To achieve a reliable design, manufacture and the desired long-term operation of the high temperature components in steam turbine, many fundamental research concerning design criteria and life prediction has been studied. However, for the steam turbine original equipment manufacturer (OEM) which design criteria and life prediction model are suitable for their product and how to accurately assess the components’ life under long-term operation is still a critical issue. For all confronted problems, the multi-axial creep failure is one of the major problems in the life prediction for high temperature components, and it is an important factor to be considered in the high temperature components design. In this paper, the creep failure mechanisms of high temperature components in steam turbine which under multi-axial stress states are analyzed, and the design criteria for creep strain and stress are presented which are based on cavity growth theory. The application of the method and design criteria in a medium pressure turbine which is included in a double reheat thermodynamic cycle plant is presented.

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