Analysis and Strategy of Ageing and Ageing Management for Steam Generator in 300MWe NPP

2008 ◽  
Author(s):  
Dong Ning ◽  
Kefeng Zhang ◽  
Weida Yao
Keyword(s):  
Operating Experience ◽  
Operating Conditions ◽  
Functional Capability ◽  
Plant Safety ◽  
Safety Margins ◽  
Gradual Process ◽  
Manufacturing Errors ◽  
Definition Of ◽  
Ageing Management ◽  
Ageing Phenomenon

The definition of ageing can be understood as a continuous and gradual process of degradation which is relative to environment, operating conditions, structure and material, etc. of components. It has characteristic of complexity that one or several factors in combination affect a component to degrade so as to result in losing function and structure failure. Much knowledge is involved in understanding and predicting degradation (ageing) mechanism as well as mitigating and managing degradation (ageing) phenomenon. Operating experience has shown that ineffective control of the ageing degradation of the major NPP components (e.g. caused by unanticipated phenomena and by operating, maintenance, design or manufacturing errors) can jeopardize plant safety as well as plant life. At present, ageing in NPPs must be therefore effectively managed to ensure the availability of design functions throughout the plant service life. From the safety perspective, this means controlling within acceptable limits the ageing degradation and wear out of plant components important to safety so that adequate safety margins remain, i.e. integrity and functional capability in excess of normal operating requirements.

Critical Speed of Flawed Rotors: Global vs Local Approach

2014 ◽  
Author(s):  
L. Scolavino ◽  
S. Beretta ◽  
M. Madia ◽  
U. Zerbst
Keyword(s):  
Critical Speed ◽  
Operating Conditions ◽  
Assessment Procedure ◽  
Local Approach ◽  
Element Analysis ◽  
Normal Operating ◽  
Safety Margins ◽  
Surface Flaws ◽  
Definition Of ◽  
Sphere Of Influence

The burst of a disc in rotating machinery can cause catastrophic damage of the equipment and, more importantly, it can represent a mortal threat to anyone in the sphere of influence of the event. In order to minimize the danger associated to a rotating component failure, burst testing is required by the authorities in order to set safety margins to the normal operating speeds. Moreover more accurate predicting tools are required for designing the components. This paper presents the results of a numerical and analytical study on the assessment of the crack driving force for discs containing surface flaws. The aim is to provide a simple, though reliable, tool in order to be able to calculate the possible dangerous in-service speed for a rotating component and, therefore, to set burst margins above the normal operating conditions of the equipment. An R6-like flaw assessment procedure is adopted considering different assumptions in the definition of the critical speed and the analytical predictions are compared with the results of elastic-plastic finite element analysis of disc. In particular, the validity and potentiality of the method is proved for surface flaws in different positions in the disc.

Approaches to the definition of territorial backwardness in the regional development management

2020 ◽  
Vol 93 (4) ◽  
pp. 60-73
Author(s):  
E. B. Veprikova ◽  
◽  
A. A. Kislenok ◽  
Keyword(s):  
Economic Growth ◽  
Public Policy ◽  
Russian Far East ◽  
Far East ◽  
Well Being ◽  
Spatial Development ◽  
Territorial Development ◽  
Development Management ◽  
Gradual Process ◽  
Definition Of

Reducing the level of interregional differentiation is one of the problems in spatial development management according to the Spatial Development Strategy of the Russian Federation. Presence of significant regional imbalances hampers formation of a common economic, social, cultural, and institutional space and lead to a creation of backward territories which lag behind in the development. The focus of public policy measures on the centers of economic growth, with the concentration of financial and labor resources, without solving the problems of backward territories does not bring the expected effect – overall development and well-being. Local effects in the absence of positive changes in other territories result in the increase in imbalances, which limit the overall effectiveness of the public policy. At the same time, a steadily increasing lag may cause a loss of potential of economic growth and thus forms backward territories. The creation of territorial backwardness is a gradual process. Therefore, diagnosing the state of the territory and identifying the signs of increasing depression is an essential issue of public administration. The article presents the main approaches to the definition of territorial backwardness used in the Russia and overseas, it also reviews the determinants of backward territories. Different methods for identification of backwardness in the territorial development have been tested on the basis of the regions of the Russian Far East.

scholarly journals A theoretical and numerical approach for selecting miniaturized antenna topologies on magneto-dielectric substrates

2015 ◽  
Vol 7 (3-4) ◽  
pp. 369-377 ◽  
Author(s):  
Alex Pacini ◽  
Alessandra Costanzo ◽  
Diego Masotti
Keyword(s):  
Near Field ◽  
Dielectric Materials ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Microwave Range ◽  
Dielectric Substrates ◽  
Full Wave ◽  
Miniaturized Antenna ◽  
Wavelength Radiation ◽  
Definition Of

An increasing interest is arising in developing miniaturized antennas in the microwave range. However, even when the adopted antennas dimensions are small compared with the wavelength, radiation performances have to be preserved to keep the system-operating conditions. For this purpose, magneto-dielectric materials are currently exploited as promising substrates, which allows us to reduce antenna dimensions by exploiting both relative permittivity and permeability. In this paper, we address generic antennas in resonant conditions and we develop a general theoretical approach, not based on simplified equivalent models, to establish topologies most suitable for exploiting high permeability and/or high-permittivity substrates, for miniaturization purposes. A novel definition of the region pertaining to the antenna near-field and of the associated field strength is proposed. It is then showed that radiation efficiency and bandwidth can be preserved only by a selected combinations of antenna topologies and substrate characteristics. Indeed, by the proposed independent approach, we confirm that non-dispersive magneto-dielectric materials with relative permeability greater than unit, can be efficiently adopted only by antennas that are mainly represented by equivalent magnetic sources. Conversely, if equivalent electric sources are involved, the antenna performances are significantly degraded. The theoretical results are validated by full-wave numerical simulations of reference topologies.

Improving the Volumetric Efficiency of the Axial Piston Pump

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Valve Plate ◽  
Piston Pump ◽  
Efficient Design ◽  
Axial Piston Pumps ◽  
Definition Of ◽  
Engineering Practices ◽  
First Time ◽  
Axial Piston

The volumetric efficiency is one of the most important aspects of system performance in the design of axial piston pumps. From the standpoint of engineering practices, the geometric complexities of the valve plate (VP) and its multiple interactions with pump dynamics pose difficult obstacles for optimization of the design. This research uses the significant concept of pressure carryover to develop the mathematical relationship between the geometry of the valve plate and the volumetric efficiency of the piston pump. For the first time, the resulting expression presents the theoretical considerations of the fluid operating conditions, the efficiency of axial piston pumps, and the valve plate designs. New terminology, such as discrepancy of pressure carryover (DPC) and carryover cross-porting (CoCp), is introduced to explain the fundamental principles. The important results derived from this study can provide clear recommendations for the definition of the geometries required to achieve an efficient design, especially for the valve plate timings. The theoretical results are validated by simulations and experiments conducted by testing multiple valve plates under various operating conditions.

scholarly journals Determining the causes, prevention and elimination of unstable modes of gas turbochargers of marine diesels

2021 ◽  
Vol 27 (1) ◽  
pp. 33-51
Author(s):  
Володимир Миколайович Калугін ◽  
Олександр Міхайлович Мунтян
Keyword(s):  
Waste Heat ◽  
Operating Experience ◽  
Optimal Solution ◽  
Operating Conditions ◽  
Heat Recovery Boiler ◽  
Effective Functioning ◽  
Contractual Arrangements ◽  
Safe Level ◽  
Air Supply ◽  
Trial Test

Annotation – With commissioning of the “Socofl Star” ship’s series, negative occurrences relative to surging of the Main Engine (ME) «Hanshin Diesel» 6LF46 turbochargers (TC) VTR 401-2. To elimination of a surging, it was necessary reduce loading of ME to the safe level. This action caused the ship’s speed to fall from 11 – 10 to 4 knots which resulted in worsening of the ship’s maneuverability characteristics and lead to the failure to provide the ship’s service speed stipulated in the contractual arrangements. Existence of this problem instigated the shipowner to charge us as experts with the mission of carrying out appropriate investigations and working out recommendations as to how to prevent and eliminate surging of TC. This task was solved on the m/v “Socofl Star”. Based on results the ME shop test and trial test of the vessel and also the saved-up data of work of ME in various conditions of swimming, the analysis of the causes of a surge of the TC was made. It is established that small values of safety factor of stability of the compressor of TC on a surging – KCT which are not allowing to ensure effective functioning of TC on the main modes of loading of ME are its reason. For increase in area of steady work of TC it is necessary to reduce the hydraulic resistance of components of the Air-Gas Path (AGP) of the ME which can be realized by changes in a design of units of air supply and gas exchange or reduction of productivity and extent of increase in pressure of air in the compressor of TC. Under operating conditions vessels an optimal solution an objective is removal of a part of blowing-off air after compressor of the TC. The air can be discharged into the flue gas header after the waste heat recovery boiler or directly into the atmosphere. This allowed the shipowner not to make constructive changes to the components of the AGP of ME and TC. The description of the operated unloading device controlled remotely on removal of air which ensures effective functioning of TC and ME that is confirmed by results of natural tests and the subsequent operating experience of vessels of the “Socofl Star” series is provided.

A Proposal for Performance Criteria for Propulsion Losses Due to Ship Steering

1982 ◽  
Vol 104 (2) ◽  
pp. 158-165 ◽  
Author(s):  
R. E. Reid
Keyword(s):  
High Speed ◽  
Operating Conditions ◽  
Relative Performance ◽  
Performance Criteria ◽  
Ship Steering ◽  
Calm Water ◽  
Simulation Results ◽  
Definition Of ◽  
Hydrodynamic Data

The problem of definition of propulsion loss related to ship steering is addressed. Performance criteria representative of propulsion losses due to steering over a range of operating conditions including operation in calm water and a seaway are considered. Criteria are derived from strict analytical considerations and from empirical assumptions based on experimentally derived hydrodynamic data. The applicability of these various criteria and the implications for both assessment of relative performance of existing ship autopilots and for the design of new steering controllers is discussed in relation to simulation results for a high-speed containership.

Operating Experience With Filled P.T.F.E. Piston Rings

1971 ◽  
Vol 93 (2) ◽  
pp. 293-301 ◽  
Author(s):  
D. Summers-Smith
Keyword(s):  
Operating Experience ◽  
Operating Conditions ◽  
Piston Rings ◽  
Satisfactory Performance ◽  
Wide Range ◽  
Considerable Experience

This paper gives details of the lives of 188 sets of filled P.T.F.E. piston rings in a variety of reciprocating compressors covering a wide range of operating conditions. Although satisfactory performance has been obtained in most cases, there has been a considerable experience of inconsistent behavior. This had led to the adoption of certain standardized practices based on the experience obtained so far in an attempt to increase the consistency of performance. In particular, these cover ring formulations and design, and the avoidance of trace quantities of lubricant.

Evaluation of acoustic emission burst detection methods in a gearbox under different operating conditions

2018 ◽  
Vol 25 (4) ◽  
pp. 895-906 ◽  
Author(s):  
F. Leaman ◽  
C. Niedringhaus ◽  
S. Hinderer ◽  
K. Nienhaus
Keyword(s):  
Acoustic Emission ◽  
Processing Technique ◽  
Operating Conditions ◽  
Detection Methods ◽  
Threshold Values ◽  
Burst Detection ◽  
Signal Processing Technique ◽  
Planetary Gearbox ◽  
Machine Condition Monitoring ◽  
Definition Of

In account of its abilities to follow the damage progression, also at early stages, the acoustic emission (AE) analysis has become an attractive technique for machine condition monitoring. An AE analysis involves the detection of transients within the signals, which are called AE bursts. Traditional methods for AE burst detection are based on the definition of threshold values. When the machine under analysis works under variable operating conditions, threshold-based methods could lead to poor results due to the influence of these conditions on the AE generation. The present work compares the ability of three AE burst detection methods in a planetary gearbox working under different rotational speeds and loads. The results showed that performance could be significantly improved by using factors of the root mean square value as threshold values instead of fixed values. Among the evaluated methods, the method that includes demodulation and differentiation as a signal processing technique had the best performance overall.

On Pipeline Lateral Buckling: Lessons Learned and Current Design Challenges

2012 ◽  
Author(s):  
Emil A. Maschner ◽  
Basel Abdalla
Keyword(s):  
Cost Effective ◽  
Lessons Learned ◽  
Operating Conditions ◽  
Design Solution ◽  
Lateral Buckling ◽  
Diverse Range ◽  
Applied Loading ◽  
Direct Design ◽  
Safety Margins ◽  
Global Buckling

The subject of lateral buckling design in recent years has by necessity become increasingly more involved as pipeline projects have moved into more difficult environments where there is a need for optimized economic solutions with assured through-life reliability. The authors have had direct design responsibility and specialist involvement with a large number of projects covering a diverse range of environments, single or PIP systems, variable product characteristics and operating conditions, external applied loading type, and geographical installation limitations. These include shallow and deep water, large thin walled and small thick walled diameter pipes, flat to undulating hard to soft seabed, variable cohesive and non-cohesive surficial soil types and various other project considerations which have impacted on the chosen design solution. The purpose of this paper will be to highlight aspects of global buckling design associated with reliable in place systems and conversely those aspects associated with integrity risks to the as-laid operational pipelines. A review of past project challenges along with a commentary as to the state of the art at the time gives an opportunity to evaluate risks and challenges being faced on current projects. Particularly, as it seeks to develop ever more cost effective designs with proven robustness but optimized safety margins for the installation and operation of HT/HP pipelines in marginal fields.

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