Estimation of Steam Turbine Shafts Fatigue Damage Caused by Torsional Vibrations

В Україні 74 енергоблоки потужністю 150-800 МВт теплових електростанцій із 102 перебувають на межі перевищення паркового ресурсу (220 тис. Годин). З них 17 енергоблоків наближаються до кінця ресурсу парку, а 11 енергоблоків досягли передбачуваного ресурсу (100 тис. Годин). Статистика аварій на електростанціях у різних країнах показує, що більшість з них спричинені тривалим накопиченням збитків від втоми. Серед основних причин пошкодження втоми - пульсація високотемпературних потоків пари в циліндрах турбіни, поперечні та крутильні коливання валів при тривалій експлуатації тощо. Це обумовлює розробку обчислювальних та експериментальних методів визначення втомних пошкоджень вали турбінних установок при динамічних навантаженнях. Оцінка втомних пошкоджень вала парової турбіни К-200-130 базується на 3D-моделі кінцевих елементів. Розрахунки враховують експериментально визначені втомні властивості роторної сталі. Розраховано втомну пошкодження в результаті крутильних коливань валу турбіни, спричинених аномальною роботою турбінного генератора. Зони концентрації напружень в обертових елементах парової турбіни типу К-200-130 встановлені для різних режимів роботи. Запропоновано процедуру прогнозування впливу втоми від пошкоджень на розрахунковий ресурс турбінного агрегату.In Ukraine, 74 power units with a capacity of 150-800 MW of thermal power plants out of 102 are on the verge of exceeding the park resource (220 thousand hours). Of these, 17 power units are close to the end the park resource, and 11 units have reached their estimated resource (100 thousand hours). Statistics of power plants accidents in different countries indicates that most of them are caused by the long term accumulation of fatigue damage. Among the main causes of fatigue damage are the pulsating of high-temperature steam flows in the turbine cylinders, transverse and torsional vibrations of shafts during long-term operation etc. This causes the development of computational and experimental methods for the determination of fatigue damage of turbine units’ shafts under dynamic loads. The evaluation of fatigue damage of steam turbine K-200-130 shaft is based on the 3D finite element model. The calculations take into account experimentally determined fatigue properties of rotor steel. The fatigue damage as a result of torsional vibrations of turbine shaft caused by the abnormal operation of turbine generator is calculated. Zones of stress concentration in the rotating elements of the steam turbine type K-200-130 are established for various operating modes. The procedure to predict the effect of fatigue damage on the estimated resource of turbine unit is proposed.В Украине 74 энергоблока мощностью 150-800 МВт тепловых электростанций из 102 находятся на грани превышения ресурса парка (220 тыс. Часов). Из них 17 энергоблоков близки к исчерпанию ресурса парка, а 11 энергоблоков вышли на расчетный ресурс (100 тыс. Часов). Статистика аварий на электростанциях в разных странах показывает, что большинство из них вызвано длительным накоплением усталостных повреждений. Среди основных причин усталостных повреждений - пульсации высокотемпературных потоков пара в цилиндрах турбины, поперечные и крутильные колебания валов при длительной эксплуатации и т. Д. Это вызывает развитие расчетных и экспериментальных методов определения усталостных повреждений. валы турбоагрегатов при динамических нагрузках. Оценка усталостных повреждений вала паровой турбины К-200-130 проводится на основе трехмерной конечно-элементной модели. В расчетах учтены экспериментально определенные усталостные свойства роторной стали. Рассчитано усталостное повреждение в результате крутильных колебаний вала турбины, вызванных ненормальной работой турбогенератора. Установлены зоны концентрации напряжений во вращающихся элементах паровой турбины типа К-200-130 для различных режимов работы. Предложена методика прогнозирования влияния усталостных повреждений на расчетный ресурс турбоагрегата

RATIONALIZATION OF THE APPROACHES OF NUMERICAL SIMULATION OF THE GEOMETRICALLY COMPLEX ROTATING EQUIPMENT OF ELECTRICAL STATIONS

The basic equipment of the most domestic power units is operated at thermal and nuclear power plants and has exhausted its design resource. Given the lack of funding for the energy sector, it is difficult to re-equip old equipment with new equipment in the near term. It is advisable to ensure a high residual experience of current equipment, based on the study of individual resource performance of specific equipment. The task of estimating the residual resource of power equipment is solved using the methods of computer simulation of separate operating modes. It is clear that taking into account all the features of a full-scale geometric model in mathematical analysis will lead to a significant increase in the human effort and resources of computer and computer engineering. Therefore, the purpose of this research is to rationalize the mathematical model of the rotor cylinder medium pressure steam turbine K-200-130. Two variants of replacement of working blades and bandage fasteners are proposed and investigated. The models are verified on the basis of a comparison of the calculated critical and natural frequencies of the rotors with the data provided by the manufacturers of the given thermal power equipment. The proposed model of rotor with replacement of the working blades with toroidal rings of equivalent length and mass has been successfully verified, and the error of calculation does not exceed 5.5%. Therefore, the rationalization method proposed in this paper can be used to reduce wasted resources in computer modeling of complex rotating equipment

Comprehensive rotor service life study for high & intermediate pressure cylinders of high power steam turbines

The paper provides a comprehensive scheme for assessment of the residual service life and extension of operating life of steam turbine rotors with expired fleet service life. The residual service life of high temperature rotors for high & intermediate pressure cylinders of К-200-130-3 steam turbine without heat grooves calculated and it was showed that the residual service life of high & intermediate pressure rotors without grooves has been extended as compared to the К-200-130-1 turbine rotors with grooves. Also residual life management by supplying hot steam to the HPC and IPC seals was investigated and it was noted their significant impact on the residual service life

BOUNDARY CONDITIONS OF HEAT EXCHANGE IN THE LACE SEALS OF CYLINDERS OF HIGH AND LOW PRESSURE OF TURBINE K-1000-60 / 3000

Purpose. Investigation of operating conditions of a wet-steam turbine with a capacity of 1000 MW, development of a calculation procedure and determination of the boundary conditions for heat transfer for end seals of high and low pressure rotors in the variable operating modes of power units for the subsequent evaluation of low cycle fatigue of the K-1000-60 / 3000 turbine rotors, determining the degree of possible damage to the main metal, calculating the residual operating time, as well as an individual resource. Methodology. When modeling the geometry of the seals, the first stage of verification calculation developed a technique for creating spatial structures of turbomachine elements using the Solid Works software and the mathematical calculation method, which is embedded in it (the finite element method) for the RVD and RND. Findings. The boundary conditions of the sections of the end seals of the RVD and RND at the starts from cold, non-heated and hot states are calculated taking into account the change in the regime parameters. It is established that the value of the heat transfer coefficient increases with increasing turbine power and has a maximum value at the nominal mode. The maximum value of the heat transfer coefficient for the RVD is α = 2168.8 W / (m2 K), for RND α = 701.5 W / (m2 · K). An approximating dependence of the heat transfer coefficient for the initial section of the high-pressure rotor on the relative steam consumption on the turbine in the range 0.4-1.0 has been obtained. Originality. The authors for the first time calculated the values of the heat transfer coefficient for the end seals of high and low pressure rotors for three types of starting-from a cold, non-heated and hot state, depending on the thermal state of the rotors and the relative steam flow to the turbine. The approximated dependence of the heat transfer coefficient for the initial section of the high-pressure rotor on the relative steam consumption on the turbine in the range 0.4-1.0 makes it possible to perform the necessary calculations for other types of starts and the temperature states of the rotors. Practical value. The results of calculating the heat transfer coefficient at the sections of the RVD and RND end seals during starts from different thermal states make it possible to calculate the thermally stressed state of the turbine rotors and to estimate the value of the low-cycle fatigue of the CVP and LPC rotors

Research on Residual Service Life of Automatic Locking Valve of Turbine K-200-130

Calculations of non-stationary thermal and stress-strain state of the casing of ALV of HPC under combined effect of temperature gradient and operational internal steam pressure were performed. Temperature gradients and pressures were assigned by variables in time under starting operation modes in accordance with actual schedules of starts, determined by the power plant. In geometric modeling, valve's lid was taken into consideration. Taking into account the lid did not have a significant impact on durability of ALV of HPC.The estimation of damage and residual service life of casings of ALV of HPC of the steam turbine K-200-130-3 showed that the total damage of metal of the casings of ALV of HPC is 84 %. The estimated residual service life of metal of the casing of ALV of HPC of the turbine K-200-130 will increase up to 164,383 hours when refining safety factors. This will make it possible to extend operation of casings of ALV of HPC by 50 thousand hours at the number of starts, equal to half the park number, that is 400 starts.To increase reliability of the elements of the turbine, to decrease thermal loads and improve the quality of operation, it is necessary to optimize the number of starts from cold state in direction of a decrease. It is also necessary to refine safety factor of metal of casings of ALV of HPC by deformations nε, the number of cycles nN, limits of fluidity nf and safety by nominal stresses nns. To do this, it is necessary to conduct studies on the impact of ageing on changes in physical-mechanical properties of structural alloy steels under operational and elevated temperatures.Results of the conducted research can be used to extend service life of locking and protective valves of steam turbines of large capacity in the energy sector

Особливості формування поля температур в стабілізаторние горілчаних пристроях при мікродифузійні спалюванні газу

The efficiency of the thermodynamic cycle of the thermoenergetic plant is defined to a great extent by burner characteristics. This scientific paper gives consideration to the formation processes of the temperature field of combustion products in the combustion chamber at microdiffusion popping of gas behind flat collectors- stabilizers with the injection of fuel into the recirculation zone that is distributed along the stabilizer length. It was shown that the profile of the gas temperature along the stabilizer height required by burner operation conditions can be provided by an appropriate change of local fuel consumption. It was noted that due to a high gradient of velocities and temperatures in the trace cross-section behind the stabilizer the mixing process of combustion products and the air in the inter-stabilizer space is characterized by a high intensity. For the studied options of burners at the stabilizer width of Bst = 30 mm and 45 mm and jam coefficients Kf = 0,6 to 0,8 the length of the chamber on which the chamber section rectification of temperature field occurs is equal to 10–15 calibers of the stabilizer and depends on the lattice density and excess air factor.Представлены результаты экспериментальных исследований формирования профилятемпературы продуктов сгорания за стабилизаторами при микрофакельном сжигании газа со струйнойподачей топлива в зону рециркуляции. Рассмотрены факторы, определяющие распределениетемпературы вдоль стабилизатора, а также длину камеры, необходимую для выравнивания температурыпо сечению камеры сгорания.Представлено результати експериментальних досліджень формування профілю температури продуктів згоряння за стабілізаторами при мікрофакельному спалюванні газу із струменевою подачею палива в зону рециркуляції. Розглянуто фактори, які визначають розподілення температури газів вздовж стабіліз

Development of A System for Estimating and Forecasting the Rational Resource-saving Operating Modes of TPP

The world energy crisis and environmental problems have prompted a rapid increase in the share of electricity generation by renewable sources. However, the operating modes of such energy facilities are rather uneven over 24 hours. Thus, for the energy sector of most developing countries, and as well as for part of developed countries, such fluctuations in the overall energy production balance lead to the forced limitation of the equipment capacity at TPPs or to the full shutdown of power units.The insufficient quantity of maneuvering capacities in the overall energy generating balance is a characteristic feature of the power systems of such countries as the Russian Federation, Ukraine, Macedonia, Bulgaria, Romania, Argentina, and others. The shortage of such capacities is often compensated for by the pulverized coal units with a power of 200–300 MW, whose operation is enabled at half-peak and peak modes. This equipment is not designed for such operations. Therefore, the development of a regime method of resource management has been proposed to prevent the premature exhaustion of TPP generating equipment.Based on technical auditing of the operational documentation of generating companies, a method has been suggested aimed at forecasting the rational resource-saving operational regimes of the high-temperature elements of power equipment by optimizing the ratio of the number of launches of the equipment from various thermal states. An optimization problem has been stated, which implies determining such a distribution of the process structural-technological parameters that would ensure the maximal preservation of equipment resource. The residual resource has been selected as the objective function of the optimization problem. The devised method has been represented in the form of a comprehensive system for estimating and forecasting the rational operational modes of the TPP high-temperature elements, which makes it possible to define individual resource indicators over the entire period of equipment operation for all possible future combinations of operational modes and to compile forecasts for thousands of different variants of power unit exploitation, implying the calculation of resource indicators for each of the

Analysis of Residual Operational Resource of High-temperature Elements in Power and Industrial Equipment

The issues of taking account of damage caused by exposure to high levels of local temperatures of gases, local non-uniformity of temperature and reliable assessment of residual resource of high-temperature elements are relevant and will provide for a reliable and long-term operation of energy generating equipment.A mathematical model is developed for the combustion process in burner devices with stabilizers based on the software complex ANSYS Fluent. We created a technique for determining the impact of levels of temperatures and their gradients on the assessment of residual resource of high-temperature elements of power and industrial equipment. Based on data on the work of industrial power equipment and results of physical experiments, we selected correct initial and boundary conditions that enabled adequate simulation of the influence of non-uniformity in the combustion products temperature field. Based on the software complex Solid Works, we performed calculation studies that take into account the gas-dynamics of gas flow that flows around the pipeline. The thermal and stress-strained states are defined and an estimation is conducted of operational lifecycle of pipeline in a boiler plant depending on the operating conditions of equipment.It was established that the residual operation time of a pipeline in a boiler plant is 77.4 thousand hours at static damageability from long-term loads of 57 %.Results of the research conducted might be used by implementing the recommendations proposed in large- and small-scale energy sector, industry and gas transportation system in Ukraine, as well as in other fields of science and technology

Development of a Technological Approach to the Control of Turbine Casings Resource for Supercritical Steam Parameters

A comprehensive model for evaluation of the resource of HPC of the turbine K-800-240-2, which includes calculation of thermal, stressed-strained state, cyclic and static damageability, is presented here. The numerical studies conducted with the use of modern methods of mathematical modeling showed a high impact of forces of pins' tightening on the stressed-strained state of the casing elements (the stress level increased by 17.7 %). A technological approach to resource control, aimed at a change in pins' tightening efforts, was proposed. It was established that this method decreases static damageability of basic metal of casings (by 9.7 %), improving its long-term strength. When taking into account tightening forces, the maximum stress intensity decreased by 9.3 %, while the stress level in the flange joint decreased by 11–41 %. These positive moments are accompanied by an increase in individual resource of the casing by 10 %. The developed concept and recommendations have significant importance for ensuring long-term operation of steam turbines with the initial pressure of hot steam at 24 MPa