scholarly journals Structural-&-Phase Condition and the Damageability of the Welded Joints of Steam Pipelines at Thermal Power Plants

2021 ◽  
pp. 56-63
Author(s):  
Vitaly Dmitrik ◽  
Igor Kasyanenko ◽  
Alexandr Krakhmalyov
Keyword(s):  
Service Life ◽  
Welded Joints ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Thermal Power ◽  
Economic Effect ◽  
Structural Phase ◽  
Initial Structure ◽  
Thermal Power Plants ◽  
Phase Condition

The authors studied the interrelation between the type of structure and the damage rate of the welded joints of steam pipelines made of the heat-resistant pearlitic steels that were operated for a long time, i.e. more than 270 thousand hours in the conditions of creepage and low-cycle fatigue. The purpose of this research was to establish the interrelation between the structural-&-phase condition of the metal used for welded joints of the elements of steam systems and their damageability rate for the service life of welded joints exceeding 270 thousand hours. During the studies, the methods of optical and electron microscopy were used according to the requirements of the guideline documentation and also the methods that are used for the determination of mechanical properties. The level of their reliability has been substantiated and the residual life has been determined. To impart functional performances to welded joints we used well-known methods that were appropriately emended according to the structural changes of above joints. Such changes condition the conversion of the original structure of welded joints into the ferrite-carbide mixture. The availability of the conversion process of the initial structure on the thermal action zone sections (TAZ) of welded joints has essential distinctions due to a different disposition of metal to its own damageability. On the whole, the welded joints are damaged more intensively in comparison to the basic metal of steam pipelines. The analysis of the structural state of welded joints in the steam pipelines of thermal power plants as for the extension of their service life results in a considerable economic effect. Understanding the fact that the metal deterioration in welded joints adheres mainly to the fragile mechanism we managed to establish the level of their damageability that demands the renewal of damaged welded joints. We believe that the damageability level of welded joints that tots up to 0.25 or 0.35 of the volume of their TAZ section should be considered as critical for the service life exceeding 270 thousand hours. The damaged welded joints should be renewed throughout the time period of 15 to 20 thousand hours as soon as the specified damageability level is attained.

scholarly journals Prerequisites for developing an advanced welding technology for repair of worn elements of steam-conducting systems

2021 ◽  
pp. 108
Author(s):  
Tatyana Syrenko
Keyword(s):  
Chemical Composition ◽  
Welded Joints ◽  
Power Plants ◽  
Thermal Power ◽  
Economic Effect ◽  
Thermal Power Plants ◽  
Repair Work ◽  
Welding Technology ◽  
Conducting Path ◽  
Mechanized Welding

The main disadvantage of standard technologies of welding steam pipelines of thermal power plants is that they can allow the presence of defective structures close to the defective ones in the metal of the seam and in the sections of the HAZ. In this regard, the question arises about the development of a new technology that will provide the appropriate structure and properties that will increase the service life of steam pipelines and get a significant economic effect. Goal. The goal is improvement of the technology of welding pipelines of thermal power plants based on the study of the features of the formation of welded joints operating in Creep conditions. Methodology. The level of wear of the elements of the Steam-conducting path was estimated taking into account the provisions of the regulatory documentation of metallographic analysis, determination of chemical composition and properties, as well as the degree of their deformation. Results. It is revealed that welded joints are characterized by initial structural heterogeneity, which is closely related to long-term strength, ductility and impact strength. For example, at different sections of a welded joint, there is a different intensity of transition of alloying elements and, accordingly, a different type of structural component can be formed. The proposed technology of welding repair of damaged elements of steam pipelines using mechanized welding in CO2+Ar provides for the production of welded joints with a higher level of uniformity of structure, chemical composition and properties. Scientific novelty and practical significance. The welding technology has been improved, which includes developing the modes for performing repair work by mechanized welding in an Ar + CO2 environment of steam pipeline samples with a depth of ≥ 20 mm and a width of ≥ 30 mm, and differs from the known ones by using linear energy welding of 1.2–1.5 MJ/m.

scholarly journals Efficiency of using heat pumps with various refrigerants in real steam turbine power units with PT-80 and T-250 turbines

2019 ◽  
Vol 140 ◽  
pp. 10001
Author(s):  
Vitaliy Sergeyev ◽  
Irina Anikina ◽  
Konstantin Kalmykov ◽  
Ivan Naletov
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Economic Effect ◽  
Electric Energy ◽  
Heat Pumps ◽  
Thermal Power Plants ◽  
Heat Sources ◽  
Utilization Factor ◽  
Energy Flows ◽  
Heat Carriers

Prospects for increasing the efficiency of heat and electric energy-generation and heat-and-power supply at thermal power plants obviously draw attention to such modern and innovative technologies as heat pumps. Heat pumps allow efficient redistribution of energy flows. The abundance of low-potential heat carriers and heat sources in the cycle arrangement of the thermal power plants operation requires modernization of production and increase of the fuel heat utilization factor, therefore, reduction of specific fuel consumption for the production of heat and electricity. This paper analyzes the influence and practicability of introducing heat pumps into the heating circuit of the return water of the heat network of power units with PT-80 and T-250 turbines. Heat pumps of various configurations provide invariant energy conversion factor and efficiency. To assess energy and economic efficiency, modeling of the operation of power units and calculation of heat pump circuits for various refrigerants are performed. The economic effect is represented in quarterly cash savings of operating costs.

scholarly journals Managing the risk of emergency situations caused by staff at thermal power plants

2019 ◽  
Vol 91 ◽  
pp. 03005 ◽  
Author(s):  
Alexander Kolesnikov ◽  
Tatiana Kokodey ◽  
Tatiana Lomachenko ◽  
Vasiliy Makarov ◽  
Sofia Pospelova
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Thermal Power ◽  
Economic Effect ◽  
Specific Area ◽  
Pilot Project ◽  
Thermal Power Plants ◽  
Project Implementation ◽  
Emergency Situations ◽  
Organizational Mechanism

Optimization of power plant operation in start and stop modes is an important task aimed at increasing the reliability and efficiency of its operation. The purpose of development of the new organizational mechanism is reduction of losses connected with incorrect actions of personnel during launching and shutdown operations of Steam-Gas furnaces of thermal power stations. The work is done on the example of one of the power plants of a large generating company. Implementation has confirmed the high efficiency of innovation. Total cost of project implementation at one station is estimated at the rate of 1.4 million rubles and the economic effect of the pilot project implementation in two years was estimated at 5.6 million rubles. It is also noted that further research is required to perform economic calculations for clarification as to which one of the new methodological approaches should be developed in the future. Conclusion was made that, first, regulation and control of personnel actions at the workplace is actually the first example of the distribution of the well-known Kaizen system and its modifications to a new specific area – energy generation. Second, the presented development can be a technological platform for further increase of the level of automation of operation of steam-gas and steam-power plants in non-stationary modes, up to full digitalization of control operation of thermal power plants.

scholarly journals Switching Coal-Fired Thermal Power Plant to Composite Fuel for Recovering Industrial and Municipal Waste: Combustion Characteristics, Emissions, and Economic Effect

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 259 ◽  
Author(s):  
Dmitrii Glushkov ◽  
Geniy Kuznetsov ◽  
Kristina Paushkina
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Power Plants ◽  
Thermal Power ◽  
Economic Effect ◽  
Combustion Characteristics ◽  
Municipal Waste ◽  
Flue Gases ◽  
Thermal Power Plants ◽  
Used Oil

Combustion characteristics were studied experimentally for single droplets of fuel slurries based on wet coal processing waste with municipal solid waste components (cardboard, plastic, rubber, and wood) and used turbine oil. We established the ignition delay time for three various groups of fuel compositions in motionless air at 600–1000 °C. The minimum values are 3 s, and the maximum ones are 25 s. The maximum temperatures in the droplet vicinity reach 1300 °C during fuel combustion for compositions with 10% of used oil. The combustion temperatures of fuel compositions without oil are 200–300 °C lower. The concentrations of anthropogenic emissions in flue gases do not exceed those from dry coal combustion. Adding used oils to composite fuels reduces the concentrations of dioxins and furans in flue gases when municipal solid waste in the fuel burns out due to high combustion temperatures. Based on the experimental research findings, we have elaborated a strategy of combined industrial and municipal waste recovery by burning it as part of composite fuels, as illustrated by three neighboring regions of the Russian Federation with different industrial structures and levels of social development. This strategy suggests switching three typical coal-fired thermal power plants (one in each of the regions) to composite liquid fuel. It will reduce the hazard of waste to the environment and decrease the consumption of high-quality coals for power generation. Implementing the developed strategy for 25 years will save 145 Mt of coal and recover 190–260 Mt of waste. The positive economic effect, considering the modernization of fuel handling systems at thermal power plants and the construction of a fuel preparation plant, will make up 5.7 to 6.9 billion dollars, or 65–78%, respectively, of the main costs of three thermal power plants operating on coal within the identical period.

scholarly journals Study of the Structural-Phase State of Pipeline Welded Metal

2021 ◽  
pp. 38-45
Author(s):  
Olena Harashchenko ◽  
Vitaly Dmytryk ◽  
Tetiana Syrenko
Keyword(s):  
Service Life ◽  
Welded Joints ◽  
Structural Changes ◽  
Low Cycle Fatigue ◽  
Structural Phase ◽  
Operating Time ◽  
Relative Content ◽  
Statistical Characteristics ◽  
Metallographic Analysis ◽  
Structural Phase State

The issues of research of structural changes as applied to welded joints of steam pipelines are considered. The results of metallographic analysis of structural changes in the metal of steam pipelines are presented. There was carried out the analysis for a number of samples cut from different sections of the steam line at different operating time under creep and low-cycle fatigue conditions. In the analyzing process of the images of micro sections, the relative content of the structural-phase components and their distribution in the metal were revealed. A comparative analysis of the statistical characteristics of the distribution and the relative content of structural components for different sections of the metal of welded joints with different operating time is carried out. A scientifically substantiated description of structural changes in the metal of various sections of samples of welded joints is given, as well as the possibility of extending the service life of elements of steam pipelines with a degraded structure and the presence of damageability. The most promising, in the opinion of the authors, directions of further research of samples to provide conditions for extending the service life of steam pipelines have been formulated and substantiated.

Structural Health Monitoring for Conventional Power Plants: Solutions for Operational Challenges

2017 ◽  
Author(s):  
Jürgen Rudolph ◽  
Steffen Bergholz
Keyword(s):  
Power Plants ◽  
Low Cycle Fatigue ◽  
Thermal Power ◽  
Assessment Method ◽  
Detailed Knowledge ◽  
Thermal Power Plants ◽  
Design Codes ◽  
Highly Qualified ◽  
Structural Health ◽  
Creep Fatigue

The load follow operation of thermal power plants in the context of the German “Energiewende” is a big challenge for those power plants. In this context TMF/SHM methods gain increasingly in importance. Most existing power plants do not actually work any more according to the load profile which was originally specified. Load monitoring with the potential of optimization of operational modes combined with highly qualified fatigue and creep-fatigue assessment modules is a central concern. A lot of new methods were developed for getting appropriate information about the structural health situation of loaded components and prevent premature damage. In this context, it is essential to process both design load data as well as information of the real operational load situation and combine this with a highly qualified assessment method based on the relevant design codes for conventional power plant components such as EN 12952-3 and EN 13445-3. In the case of thermal power plants both fatigue due to cyclic loading and creep due to high temperatures (and their combination) play an important role. Note that there is a change of dominating damage mechanisms and dominating damage locations (from creep towards low cycle fatigue) due to new (load follow) operating modes. This implies the qualified assessment of fatigue damage respectively combined creep-fatigue phenomena. Due to the detailed knowledge of stress histories, temperatures and the duration of hold times a best forecast can be given. A staged concept is envisaged consisting of a simplified estimation according to conventional design codes (EN 12952-3 / EN 13445-3) and a detailed solution based on the application of a non-linear material model.

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