Thermomechanical Equipment Research Articles

ANALYSIS OF THE MAIN APPROACHES TO THE ASSESSMENT OF THE CONDITION OF TPP AND NPP EQUIPMENT

The materials of the article analyze the current state of the energy industry in Ukraine and the countries of the world and analyze the ways to increase the efficiency of thermal power plants and nuclear power plants. The elements of the power unit can be affected by aging processes that occur over time or as a result of long-term use. The negative impact of aging can lead to the degradation of the element, namely to the deterioration of its reliability and, as a result, the safety of the power unit as a whole. The development and implementation of measures to mitigate aging processes and to ensure reliable operation of elements during the reassigned resource period is a mandatory type of activity for managing the aging of thermomechanical equipment and pipelines.Monitoring of the technical condition of the elements is performed by monitoring the established parameters and characteristics that determine the technical condition of the elements, during their operation, during tests, measurements, operational control of metal, repairs and maintenance of the elements. Monitoring should be carried out systematically throughout the entire life of the power unit. In turn, technical diagnostics monitors the current state of all elements, detects abnormal conditions, determines the causes of their appearance, which allows you to assess the situation and take measures to eliminate them. The purpose of the article is to analyze the main approaches to assessing the state of energy equipment of thermal and nuclear power plants.

Study of the Effectiveness of the Transition from an Open Heat Supply Systems to a Closed One

A promising direction in terms of improving heating networks is the transition from an open heating system to a closed one, which meets modern requirements fixed at the legislative level. However, the effectiveness of such measures is ambiguous. Despite the fact that closed systems maintain high quality water for hot water supply, stable hydraulic mode, automatic regulation of heat supply, their advantages are questioned. At the same time, open systems have significant advantages that, in some cases, give preference to: low corrosion rate of metal in pipelines and equipment due to the use of boiler-quality heat transfer agent that has been processed at a heat source, low cost of ITP, due to the lack of heat exchange devices that increase the cost of thermomechanical equipment, the use of exhaust steam from turbines of thermal power plants and thermal power plants, which increases the efficiency of heat supply. The disadvantage is the low quality of water for hot water supply systems and the need to replenish open heating networks with large volumes of prepared and treated water. A comparative analysis of costs in the transition from an open heating system to a closed one is devoted.

SIMULATION STUDY OF THE DIGITAL TEMPERATURE SENSOR OPERATION IN CASE OF A NON-STANDARD MECHANICAL IMPACT OF THE NPP EQUIPMENT

The article presents the results of an experimental study relevant to the effective organization of temperature control of thermomechanical equipment at nuclear power plants (turbines, pumps, steam generators, deaerators, etc.). Bench studies of the reaction of the DS18B20 digital intelligent temperature sensor, which is supposed to be introduced at Ukrainian nuclear power plants, to the application of external compression force to its body, which may occur under conditions typical for the operation of equipment operating at nuclear power plants, have been carried out. An electrical circuit diagram has been developed for a reset signal simulation device (for bench modeling of a sensor application system). The issues of identifying a sign in the sensor output signal informing about the effect of an external compression force on its body are considered. The technique of bench experiments and processing of research results necessary to address the issue of introducing new digital measuring equipment for temperature control of thermomechanical equipment of nuclear power plants is given.

Regarding Requirements to Load Combinations in Case of Evaluation of SSC Seismic Resistance by Indirect Methods

Extension of the list of load combinations that should be analyzed during the nuclear power plant (NPP) components seismic resistance justification is one of the important new regulatory requirements.
 The paper deals with the thermomechanical equipment for which seismic resistance assessment is performed using operating experience method, in particular the methodology of indirect assessment using the GIP (Generic Implementation Procedure) for the WWER reactors (GIP-WWER procedure).
 Review of GIP-WWER procedure has been performed. The paper presents the analysis of seismic screening evaluation work sheet based on the example of motor-operated valve. The disadvantages of the GIP-WWER procedure in terms of ensuring compliance with current regulatory requirements for combinations of operating and seismic loads have been identified and the ways of eliminating the revealed disadvantages have been offered.
 The supporting structures of the equipment in most cases are the metal structures. Impact of different NPP operating modes to the steel supporting structures of the equipment has been considered and the provisions of building codes governing the calculation of steel support structures have been analyzed. A minimum listing of operating and seismic loads combinations has been established, which should be considered in the justification of the seismic strength of steel support structures referred to the first and second seismic categories.
 The paper is a part of a series of publications devoted to consideration of regulatory requirements to combinations of operational and seismic loads in assessing the seismic resistance of NPP components.

Thermal Method for Non-Destructive Control of Actual Coolant Mass Flow through a Heating Device

The studies show that expenses for heating buildings and structures account for more than 60% of total utility costs in the Russian Federation. Therefore, the issues on energy and resource conservation and improving the energy efficiency of construction projects for various purposes are relevant and priority. Infrared thermography is actively used during examination of thermomechanical equipment, building structures, external and internal engineering systems and their elements. Heat monitoring makes it possible to avoid significant costs for dismantling of controlled objects and to localize the thermal defects found during the inspection stage, thereby reducing costs of repair works. The article considers and analyzes the existing options for the quantitative analysis of thermograms. The authors propose a new method for quantitative processing of thermograms, aimed at assessing the operation of heating devices in heating systems of buildings and structures. The essence of thermal non-destructive testing technique is to determine the actual mass flow rate of coolant through the heating device.

Some Aspects of Practical Application of Regulatory Requirements Related to Operating and Seismic Load Combinations for Thermomechanical Equipment and Piping

New state-of-the-art regulatory document has been developed and implemented in Ukraine to present requirements for seismic hazard assessment of nuclear power plant (NPP) sites and seismic resistance of nuclear power units taking into account lessons learnt from the accident at Fukushima-1 NPP. One of the new important regulatory requirements in this document is the extension of the list of mandatory load combinations, which should be considered in assessing seismic resistance of unit components.
 Advantages and disadvantages of the algorithm proposed by the operating organization to determine the necessity to consider some load combinations in assessing the seismic resistance of pipelines and thermomechanical equipment based on previously performed seismic strength calculations have been analyzed in the paper. The pipelines as well as the thermomechanical equipment of Zaporizhzhya NPP Unit 3, for which seismic strength evaluation was calculated, have been considered.
 The results of expert seismic calculations of YP13S02 valve of ZNPP-1 and ZNPP-3 have been provided. The paper presents the comparative analysis of the floor response spectra for the lower, middle and high elevations of ZNPP-3 containment with the corresponding floor response spectra of other Ukrainian NPPs and conclusions.
 The possibility for disseminating results obtained by the operating organization for ZNPP-3 to other units of the Ukrainian NPPs has been analyzed.

Biodegradable Poly(butylene succinate‐co‐terephthalate) Fibers Incorporated with Nanoparticles under High Drawing Temperatures for Enhanced Mechanical Properties

AbstractThe performance of materials depends strongly on their microstructures which, in turn, are dependent on the processing parameters. In this work, the emerging and biodegradable poly(butylene succinate‐co‐terephthalate) (PBST) nanocomposites with different nanoparticles (NPs) are generated via in situ polymerization and the corresponding composite fibers are fabricated via melt‐spinning for the first time. The NPs play a role as nucleating agents and can increase the crystallization rate. The real‐time investigation of evolution of fibers during uniaxial stretching is carried out on synchrotron radiation small‐angle X‐ray scattering beamline integrated with a thermomechanical equipment, so as to identify the effects of drawing temperatures and NPs on lamellar structure. Both the existence of NPs and high drawing temperature are beneficial to the formation and perfection of new lamellae. Moreover, NPs and relatively high temperature can improve the break strength of PBST fibers by 10–20%, which is reasonable according to the findings in structure development. Furthermore, the method employed here for property improvement of PBST fibers sheds light on performance optimization of other polymers and fibers.

Research of impact of kind resuperheat and structure of system regenerative feed water to thermodynamic efficiency of cycle with steam-coolant reactor

The first key problems of modern nuclear reactors are inability of closed nuclear cycle, problems with spent nuclear fuel, poor effectiveness of nuclear fuel and heat-exchange equipment usage. Dealing with problems consists in usage of fast-neutron reactors with steam coolant. Scientific men analyzed neutron-physical processes in steam-cooled fast reactor and consulted that creation of the reactor is viable. In consequence of low steam activation a single-loop steam cycle may be create. The cycle is easy and fool-proof. Core thermomechanical equipment has mastered and has relatively low metal content. Results of calculation are showing that nuclear unit with steam-coolant fast neutron reactor is more efficient than widely used unit with reactor VVER. Usage of simple scheme with four regenerative feedwater heaters the absolute efficiency ratio is more than 43%.

Line summary of approaches for improving vibrational reliability of thermomechanical equipment and its interconnecting pipelines at thermal power plant

A central problem in engineering of power-generating equipment, beside the quest for economy, is the problem of ensuring reliability of equipment and branched pipeline systems for circulation of process media. When analyzing causes of component failures in thermomechanical installations, flow control devices and pipelines, it should be noted that such failures most often result from dynamic loads on walls of these objects exposed to flowing media. Such loads are an immediate result of turbulent flow of the process medium. This turbulence is characterized by extremely non-uniform flow field and pressure pulsations of significant amplitude occurring in a broad band of frequencies. For that reason, this paper will be mainly concerned with the development and experimental studies of new approaches to dampening flow perturbations introduced by flow control devices, turbine stages, flow direction changes at pipeline bends, control valves of steam turbines etc. Findings are presented as specific examples showing the potential for a sharp reduction of dynamic loads on walls of various devices exposed to flowing medium. These involve both specially designed aerodynamic filters and direct action to modify flow behavior of the process medium in areas adjacent to walls. It is shown that the application of proposed pulsation dampener designs has the potential of twofold to threefold improvement in vibrational reliability of equipment and its interconnecting pipelines.

Research on the Hot Deformation Behavior of Al-Zn-Mg-Sc-Zr Alloy During Compression at Elevated Temperature

The flow behavior of Al-Zn-Mg-Sc-Zr alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermo-mechanical equipment. Compression tests were performed in the temperature range of 340-500 °C and in the strain rate range of 0.001-10 s−1.The results indicate that the flow stress of the alloy increases with increasing strain rate at a given temperature, and decreases with increasing temperature at a given imposed strain rate. The relationship between flow stress and strain rate and temperature was derived by analyzing the experimental data. The constitutive equation of Al-Zn-Mg-Sc-Zr alloy during hot compression deformation can be described by the Arrhenius relationship of the hyperbolic sine form. The values of A, n, and α in the analytical expression of strain rate are fitted to be 1.49 × 1010 s−1, 7.504, and 0.0114 MPa−1, respectively. The hot deformation activation energy of the alloy during compression is 150.25 kJ/mol. The temperature and strain rate have great influences on microstructure evolution of Al-Zn-Mg-Sc-Zr alloy during hot compression deformation. According to microstructure evolution, the dynamic flow softening is mainly caused by dynamic recovery and dynamic recrystallization in this present experiment.

Operating lifetime of basic thermomechanical equipment at JSC “Mosénergo”

A sequence is described for extending the service lifetime of the main thermomechanical equipment after it has outlived its intended lifetime. A general rating of the state of the boiler drums of a power plant is given after they have been inspected. A brief description is given of a combined approach to evaluating the engineering state and residual lifetime of the steam superheating surfaces of boilers based on magnetic monitoring, ferritometry, and studies of the structure and properties of the metal in incisions. It is shown that, despite periodic impairment of casing components and, less often, of the rotors of steam turbines, they have significant reserves in their individual service lives provided rational use is made of regular repair technologies. Various repair techniques used at heating and electric power plants for recovery of the worn leading edges of the blades of steam turbines are described briefly. The state of the steam lines at the Mosenergo electric power stations is evaluated. The essential idea and advantages of a technique for extending the lifetime of steam lines in heat and electric power plants through a thermal recovery treatment are illustrated.

Operational Reliability and Prospects of Continuation of Service of the Thermomechanical Equipment of the Surgut GRES-2

The condition of the thermomechanical equipment of 800-MW power generating units of the Surgut State Regional Power Plant (GRES-2) after twenty years of operation is analyzed. Attention is concentrated at “problem” units and components of the equipment that have exhausted the scheduled service life or had been damaged considerably during operation. Abrief report of the results of a study of the metal of the power equipment is presented and measures are suggested for raising the reliability and efficiency of generating units of the Surgut GRES-2.

Upset Deformation of Amorphous Mg<SUB>85</SUB>Y<SUB>10</SUB>Cu<SUB>5</SUB> Alloy in an Extended Supercooled Liquid Region Effectuated by Rapid Heating

We have developed a new thermomechanical equipment in which the sequential processes consisting of rapid heating at a rate of 300 K/s, upset deformation at a speed of 50 mm/s and immediate water cooling can be performed through a computer program. This equipment is expected to enable the deformation of an amorphous alloy into various shapes by utilizing the viscous flow resulting from the extension of the supercooled liquid region caused by the rapid heating. By using the equipment, the changes in T g and T x by rapid heating were also examined for an amorphous Mg 85 Y 10 Cu 5 alloy in the cylindrical shape of 5 mm O ×10 mm