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A comparative experimental study of the structure and properties of 25Kh1M1FA steel rotor metal from a PT-60-90 turbine is conducted after operation for approximately 400 thousand hours and appearance of a crack in the axial channel, and from a PT-60-130 turbine after additional thermal aging equivalent 600 thousand hours at a live steam temperature of 555°C. Despite the absence of obvious signs of recrystallization within the metal microstructure, after ageing there is a significant, up to ~1.5 times, decrease in metal hardness and other short-term strength mechanical properties. Weakening is not related to the diameter and distance between relatively large (over 1 μm) particles. A negative effect of decreasing molybdenum content in solid solution on strength is demonstrated. Stress-rupture strength for 100 thousand hours at 525°C decreases by a factor of 1.4, due to which the value of the guaranteed service life of a PT-60-130 turbine rotor after ageing at 650°C decreases from 1.7 × 105 to 1 × 105 h. Brittle failure resistance increases, i.e., the metal critical brittleness temperature decreases from 56 to 42°C. It is found that appearance of a crack in an axial channel is not necessarily accompanied by a large degree of bainitic component spheroidization (more than 3 points). A reduction in PT-60-90 turbine rotor metal hardness to a lower permissible level of 180 HB occurs after about 50 thousand hours, which indicates that the PT-60-90 turbine may be operated up to 450 thousand hours. [ABSTRACT FROM AUTHOR]

In recent years, researchers have been studying the role of journal bearings in the thermohydroelastic instability of the rotor. This phenomenon is referred to as the Morton effect. To assess this effect, we numerically analyzed the thermal state of a pad bearing of a turbine-generator set during vibrations of its rotor. The results obtained were used to evaluate the thermohydroelastic effect in the journal bearing on its instability manifested as an increase in the trunnion temperature at the high point and the associated increase in the vibration of the shaft. [ABSTRACT FROM AUTHOR]

The results of mathematical simulation and experimental study of the dynamic behavior of the turbine drum rotor carried out because of the unsatisfactory vibration characteristics revealed during bench tests of the turbine- coupling-hydrobrake rotor system are presented. The main design features of the bench rotor system that influence its dynamic performance are considered. The spectra of frequencies and modes as well as the amplitude- frequency response of the rotor system excited because of the unbalance of the turbine rotor or the coupling span are determined. For computational purposes, software developed by the authors was used. The algorithm for mathematical simulation of rotor vibrations is based on the modal expansion method for the conservative rotor-bearings system. It is shown that the rotor can roll over the stator, which is the main cause of an emergency situation. Based on the computed and experimental results, the causes of failure of the upstream bearing are analyzed. [ABSTRACT FROM AUTHOR]

The article considers some issues of oscillations of turbine shaft assemblies, which have not yet received sufficient coverage in Russian technical literature. These include the problem of diagnosing defects that cause a change in rotational vibration, issues of the influence of rotor oscillations on the accuracy of RPM measurement in control systems. In a statement manner, the problem of the thermohydroelastic effect manifestation in plain bearings in power turbine units is considered. [ABSTRACT FROM AUTHOR]

This article presents details of the mathematical modeling of the gas flow and temperature distribution in the rotor winding of a turbine generator with self-ventilation from sub-slot channels. In particular, the possibilities of adjusting the geometry of the sub-slot channel to minimize the temperature differences of copper conductors within the slot part of the winding are discussed. The data calculated are compared with the ventilation experiment on a rotating physical model of the rotor and the results of full-scale thermal tests of operating turbine generators with air and hydrogen cooling. [ABSTRACT FROM AUTHOR]

An analysis of existing methods for determining the natural frequencies of torsional vibrations of the shaft trains in power turbine units is carried out in order to assess the potential for using changes in natural frequencies to diagnose shaft damage. A computational modeling of torsional vibrations of a shaft train having a circumferential crack allowed informative natural frequencies to be determined for the purposes of detecting damages and the locations of natural frequency measurements to be established to a satisfactory degree of accuracy. An assessment of changes in natural frequencies from depth and characteristic locations of a circumferential crack is carried out. An alternative method for detecting violations of the shaft train integrity, based on monitoring changes in the angles of static twisting, is also considered. [ABSTRACT FROM AUTHOR]

The main activities conducted at the department for technical diagnostics and repair technologies of the All-Russia Thermal Engineering Institute (JSC "VTI") are described. It is shown that the diagnostics of the main and auxiliary power equipment can be efficiently performed using specialized monitoring tools. Effective methods and tools for assembling rotor couplings of turbine units are presented. Technologies for repairing the blade apparatus of steam turbines arereviewed. [ABSTRACT FROM AUTHOR]

The principles of a program for monitoring stresses in rotors and bodies of stop and control valves of nonreheat steam turbines of up to 180 MW capacity to control the startup processes are formulated. The program based on the experimental data obtained by the VTI and ORGRES and calculated results obtained with the finite-element method is intended for microcomputers with hardware integrated into the electronics of the control system or the automatic process control system. Using the data from the regular control and measuring instruments, the program estimates the stresses in the "critical" elements of the steam turbine, compares them with the level permissible for the material, depending on the operating temperatures, service life, design and other parameters, and generates signals to adjust the startup process. The equivalent operating hours can also be calculated to assess the quality of startups and shutdown processes, accumulated damage, and relative past life. These data can be taken into account when deciding on maintenance operations. The algorithm of the stress monitoring system is implemented in the program limiting the rate of spinup and power change from the thermal stress state of the rotors of the high- and intermediate-pressure cylinders of the T-185/210 – 16.0 turbine. [ABSTRACT FROM AUTHOR]

Research developments on repair techniques and technologies for rotor shafts by welding and surfacing are presented. Most common defects of rotor shafts are classified. Requirements for welding materials, welding methods, and repair item are formulated. These requirements and repair technologies are based on computer simulation validated experimentally. [ABSTRACT FROM AUTHOR]

The principles of a program for monitoring stresses in rotors and bodies of stop and control valves of nonreheat steam turbines of up to 180 MW capacity to control the startup processes are formulated. The program based on the experimental data obtained by the VTI and ORGRES and calculated results obtained with the finite-element method is intended for microcomputers with hardware integrated into the electronics of the control system or the automatic process control system. Using the data from the regular control and measuring instruments, the program estimates the stresses in the "critical" elements of the steam turbine, compares them with the level permissible for the material, depending on the operating temperatures, service life, design and other parameters, and generates signals to adjust the startup process. The equivalent operating hours can also be calculated to assess the quality of startups and shutdown processes, accumulated damage, and relative past life. These data can be taken into account when deciding on maintenance operations. The algorithm of the stress monitoring system is implemented in the program limiting the rate of spinup and power change from the thermal stress state of the rotors of the high- and intermediate-pressure cylinders of the T-185/210 – 16.0 turbine. [ABSTRACT FROM AUTHOR]

Present-day approaches to problems of substantiating the possibility of further operation of power equipment after long accumulated operating time in the presence of defects and deviations from the requirements of the standards are presented for the example of rotors of powerful turbine generator sets. The serviceability of the structure for an extended period is confirmed on the basis of works based on a calculated assessment of safety factors according to various limit states criteria. [ABSTRACT FROM AUTHOR]

There were emergency situations where 20MWgas turbine units on metal foundations operated in permafrost areas were tripped by the vibration protection system. Using advanced vibration diagnostic facilities made it possible to reveal design defects of the equipment. Balancing and foundation stiffening have brought the operation of turbines in line with the operating rules and regulations. [ABSTRACT FROM AUTHOR]

A new design of two-pole turbogenerators intended to operate in combination with steam or gas turbines of low and medium capacity is described. Anumber of modifications in the conventional design and manufacturing process of the rotor and stator made it possible to minimize the weight and dimensions of the generator, to reduce the labor-output ratio, and to improve its operational reliability, while keeping its efficiency high. Bench and field test results for several turbogenerators of the series, which indicate large margins for thermal and vibration characteristics of the new design, are presented. Data on the commercial operation of such turbogenerators are presented. [ABSTRACT FROM AUTHOR]

Consideration is given to the relevance and stages of the development of the acoustic-emission (AE) technique for detecting fatigue cracks on the shafts of the intermediate- and low-pressure rotors of turbines at thermal power plants. Examples of AE testing of rotors with differently loaded shafts are given. The main stages in the nondestructive testing of the intermediate- and low-pressure rotors of turbines at thermal power plants without dismounting the shrunk-on disks during maintenance are outlined. [ABSTRACT FROM AUTHOR]

Initial results on the development and operation of the 330 MW pulverized-coal fired unit at the Kashira GRÉS are reported. The major performance indices are close to the design values. The remaining unsolved issues are singled out. [ABSTRACT FROM AUTHOR]

The effect on the condition of the rotor material owing to multicycle fatigue caused by variable stresses during participation of a power generating unit in grid frequency and power regulation is evaluated using the K-300-23.5 steam turbine as an example. It is shown that during normalized primary frequency regulation the safety factor is at least 50, while during automatic secondary regulation of frequency and power there is essentially no damage to the metal. [ABSTRACT FROM AUTHOR]

Aspects of the vibrational state of blades and shaft lines during transitional operation of high-power steam turbines are examined. Measurements are made using a modernized version of the discrete phase method. It is shown that synchronization and load resetting do not lead to dangerous dynamical stresses in the blades and shaft components. [ABSTRACT FROM AUTHOR]

study of wet-steam erosion of the disks and the rotor bosses or housings of turbines in thermal and nuclear power plants shows that the rate of wear does not depend on the diagrammed degree of moisture, but is determined by moisture condensing on the surfaces of the diaphragms and steam inlet components. Renovating the diaphragm seals as an assembly with condensate removal provides a manifold reduction in the erosion. [ABSTRACT FROM AUTHOR]

The results of research on the causes, forms and aftereffects of the occurrence of defects and damage to the stators and rotors of generators are presented. The processes of ageing of the materials of machine parts are analyzed. A list of the developments of methods and apparatus for generator flaw detection is presented. [ABSTRACT FROM AUTHOR]

A brief review of methods and means of diagnostics and monitoring of steam-turbine blades is made, informational criteria for determination of the defective status of blades are defined only by peripheral sensors, and a developed block diagram is presented for a system in the form of a software package to be used in monitoring the deformed status of blades and to ascertain their defective status. [ABSTRACT FROM AUTHOR]

Results of analysis of the melting of rotor leads in turbogenerators during the period from 2001 through 2005 are presented. A distribution of the number of damages sustained by generators with respect to type, time, type of studs, active and reactive loads at the time of failure, etc. is given. It is established on the basis of electric-contact theory that one of the basic causes of the melting of the contact components of rotor leads is misalignment of the head slots of the contact stud and its skewness in the threaded hole of the contact rod. Recommendations are given for prevention of misalignment of current leads. [ABSTRACT FROM AUTHOR]

Disturbance of the grounding of the shaft of a turboset or its absence for technical reasons can result in failure, misoperation, limitation of the operating zone, errors or limitation of the sensitivity of devices for control and protection of exciting circuits from single-point leakage, and electroerosion of elements of the turboset structure. Measures for increasing the reliability of the grounding of the shaft are discussed. [ABSTRACT FROM AUTHOR]

Examples of complex cases of vibration adjustment of high-power turbosets of type K-800-240 and K-1000-60/3000 LMZ at power plants are considered. Diagnostic features of some defects strongly affecting the vibration of bearings and rotor journals are described. [ABSTRACT FROM AUTHOR]

Computational and experimental results obtained for active turbines are used to show that the pulsation of steam rate due to self-excited vibrations of the valves of the high-pressure cylinder can cause rotor vibration accompanied by damage of support pillows and disturbance of the external anchoring of the nozzle vanes. [ABSTRACT FROM AUTHOR]

It is proposed that the flange joints for turbine rotors and for the horizontal feedthrough of the cylinder housings be assembled using a technology that avoids traditional impact tools, as well as heating of the studs. This technology involves the use of specialized equipment and a modified fastener design. The insertion (extraction) of the fastener is monitored both with a dial indicator and based on the jack force measured by the pressure from the hydraulic pump, which reduces the errors owing to human factors. [ABSTRACT FROM AUTHOR]

The types of endoscopes and techniques of their use for examining stators and rotors of turbogenerators are considered. It is shown that endoscopy is a very effective method for determining defects and faults in generators of the Tyumenénergo power plants with a capacity of 200 and 800 MW. Examples of determination of critical defects are presented. [ABSTRACT FROM AUTHOR]

The types of endoscopes and techniques of their use for examining stators and rotors of turbogenerators are considered. It is shown that endoscopy is a very effective method for determining defects and faults in generators of the Tyumenénergo power plants with a capacity of 200 and 800 MW. Examples of determination of critical defects are presented. [ABSTRACT FROM AUTHOR]