Ewa DOBKIEWICZ-WIECZOREK
Method for calculating the exhaust steam pressure of a condensing turbine
The paper presents methods for calculating the exhaust steam pressure of a condensing turbine based on technical data of the surface condenser and cooling water parameters. Three methods of calculating heat transfer coefficient based on criterion equations, HEI method and ASME standard were compared. The assumptions and simplifications of the presented model are discussed. Examples of calculation results are presented, which were compared with the design data of real unit. Validation of the models based on real data was done. The most advantageous model was indicated.
Keywords: condensing turbine, exhaust steam pressure, methods of calculating heat transfer coefficient
Bolesław AUGUSTYNIAK
Determination of the stress using the Barkhausen effect – comparative research and method development perspective
The paper presents the results of comparative tests of stress state in steel structure elements made with the use of the Barkhausen effect (EB) with the results of tests by X-ray diffraction, Mathar method (welded joints and steam pipeline of steel 13HMF) and trepanation method (welded joints after stress relief treatment). The assumptions of NNT’s research and development project NCRD are also described. Its aim is to develop an EB effect meter that will indicate the values and directions of the main stress components in real time.
Keywords: stress state in steel structure elements, the Barkhausen effect, an EB effect meter
Ryszard BARTNIK, Zbigniew BURYN, Anna HNYDIUK-STEFAN
Thermal and economic effectiveness of a gas turbine set coupled with a turboexpander in a hierarchical gas-gas system
Analyzing the costs of electricity and heat production in hierarchical power plants and gas-steam CHP plants, it appears that a very important aspect related to this cost is associated with the capital investment in the steam-based system. Therefore, attempts should be made to find a way to reduce the cost of electricity and heat production related to the steam-based system installed in the hierarchical power plants and gas-steam CHP plants. For instance, in the place of installing a steam turbine in them, it is possible to consider the use of a turboexpander with a compressor and an air preheater. This paper contains a report concerned with the thermal and economic analysis of such a system design.
Keywords: turboexpander, compressor and an air preheater, the thermal and economic analysis of a system design
Andrzej BŁASZCZYK, Mariusz NAWROCKI, Dariusz WOŹNIAK
Identification of excessive vibration cause of the feed pump installation of high power energy unit
Extending the required operating range of flow pumps, especially towards smaller capacities, may lead to the appearance of various operational problems, important from the point of view of reliability, and often difficult to diagnose in the conditions of continuous operation installations. One such problem is unstable pump operation. The phenomenon is particularly dangerous in large installations due to the large masses, forces and energy that occur at that time. The article presents the case in which during the block operation at partial load the feed pump work area was revealed, in which there were clear pulsations of flow parameters and the dynamic state of the pump as well as the boiler hydraulic system. Pulsations occurred even though the pump was operating relatively far from the minimum capacity limit specified by the pump manufacturer.
Keywords: unstable pump operation, pulsations of flow parameters, identification of excessive vibration cause
Janusz DOBRZAŃSKI, Hanna PURZYŃSKA
Method to assess the condition of a superheater chambers after a long operation beyond a boiler design service life
Presented is the procedure of condition assessment and determination of time and further operation of a superheater chambers’ material working in creep conditions far beyond the design service life. Moreover, a brief review is made of proceeding steps that were taken in the frames of the elaborated algorithm. Briefly discussed and shown on an example are also selected characteristic steps of the adopted procedure.
Keywords: assessment of the material condition, operation of a superheater chambers’ material, material creep
Janusz DOBRZAŃSKI, Hanna PURZYŃSKA
Method to assess the condition of material of power units turbine rotors after a long operation in creep conditions beyond the design service life
Presented is the algorithm of proceeding during the material condition assessment and determination of time and further operation of turbine rotors. Brief review of every individual step of the adopted procedure has been made and the selected characteristic steps are shown on the example.
Keywords: assessment of the material condition, rotors of power units turbines, long time operation, material creep
Grzegorz GOLAŃSKI, Hanna PURZYŃSKA, Michał KWIECIEŃ
Analysis of change in microstructure and mechanical properties of TP347HFG austenitic stainless steel after service at 585oC temperature
The paper presents the results of research on the austenitic microstructure of creep-resisting TP347HFG steel after service at the temperature of 585oC. The performed microstructural tests showed that the service of the examined steel contributed mostly to the precipitation processes, particularly on the boundaries of grains, where the M23C6 carbides and the sigma phase precipitates were observed. The precipitation strengthening with numerous precipitates resulted in high strength properties in the case of the investigated steel in the after-service condition. The fine-grained microstructure and the presence of twins in the steel structure allowed maintaining relatively good plastic properties and toughness.
Keywords: research on the austenitic microstructure of creep-resisting TP347HFG steel after service at the temperature of 585oC
Rafał HYRZYŃSKI, Paweł ZIÓŁKOWSKI, Sylwia GOTZMAN,
Bartosz KRASZEWSKI, Janusz BADUR
Analysis of the energy storage system in the CAES coupled with the underground thermal energy storage
Flexible and dispatchable power plants will contribute to this ongoing transformation process as they compensate for fluctuations in electricity generation from renewable energy sources such as wind and photovoltaics. In this context, CAES (Compressed Air Energy Storage) storage tanks are currently the only alternative to storage using pumped storage because of the possibility of obtaining the appropriate storage energy capacity. However, a relative disadvantage of these plants is the heat loss caused by the cooling of the air after compression. In this paper, the situation of cooperation between the current conventional power plants and wind farms is first analysed, and then, based on thermodynamic models, the process of storing thermal and electrical energy in the CAES system coupled with heat recovery after the gas turbine is analysed. A solution with a ground heat exchanger was also proposed, as the soil, due to its properties, may serve as a thermal energy storage.
Keywords: cooperation between the conventional power plants and wind farms, storing thermal and electrical energy in the CAES system coupled with heat recovery after the gas turbine
Stanisław MROZIŃSKI, Zbigniew LIS
Studies influence of creep on low-cycle fatigue
The paper presents results of the steel P91 fatigue tests in variable load and creeping at T = 600oC. Comparative analysis of test showed that the order of variable loading and creeping program affect life of material.
Keywords: the steel P91, studies influence of creep on low-cycle fatigue
Wojciech PIECHA
Basic assumptions as well as regulation and supervision methods of the work of high pressure pipelines mounting systems with reference to the UDT NR 2/UC/2019/1 guidelines
Mentioned is an important problem of controlling the work of high parameters pipelines mounting systems working in conditions of high temperature and pressure. Discussed is the influence of the mounting systems on a pipeline work and its service life. Presented is also the method to make use of the modern mounting systems technical properties for diagnosing systems’ work and the assessment of pipelines technical condition. The subject area of this article refers to the published in 2019 „Wytyczne Urzędu Dozoru Technicznego UDT Nr 2/UC/2019/1” [1] (The Guidelines of the Office of Technical Inspection Nr 2/UC/2019/1 [1]).
Keywords: mounting systems of high pressure pipelines, methods of regulation and supervision, UDT NR 2/UC/2019/1 guidelines.
Adam WOJACZEK, Andrzej RUSIN
Selected technical aspects affecting Small Punch Testing accuracy
A thorough technical state analysis focusing particularly on the state of the power unit most loaded elements is the basis to determine the possibility of their further operation. Conventional destructive testing methods involve sampling large amounts of the tested material, which is often impossible. In such cases Small Punch Testing (SPT) is an effective method because it makes use of micro specimens. The SPT procedure has many technical aspects affecting the testing repeatability. The paper presents the impact of the specimen thickness, the indenter advance speed and the specimen clamping force.
Keywords: Small Punch Testing (SPT) method, micro specimens, impact of the specimen thickness, the indenter advance speed and the specimen clamping force
Stanislav VESELÝ
Calculation of thermal stresses of a combustion chamber selected parts and the forecast of the length of their service life
In the stable over time gas turbine operating conditions there occur uneven temperature fields in the combustion chamber flame tube that are the cause of formation of thermal stresses and distortions. It can be the reason of damages cumulation and development of fractures in the flame tube fed with natural gas. Presented is the method enabling calculation of the temperature of a flame tube wall exposed to the radial heat flux from the flame and cooled with air. A focus is put on a complex problem concerning the heat exchange on the wall. Presented is the single equation of a heat flux and the equation of thermal equilibrium on the basis of which the values of wall temperatures were calculated. Further on there is shown the method to calculate the temperature field and thermal stresses of a flame tube and conducted is the stress analysis.The service life of a flame tube has been forecast considering the low-cycle fatigue and creep.
Keywords: thermal stresses of a combustion chamber selected parts, forecast of the service life of the parts, heat exchange on a chamber wall
Paweł ZIÓŁKOWSKI, Sylwia GOTZMAN, Janusz BADUR
Improved flexibility of steam plant and CCGT plant operation through the use of steam storage tank
The purpose of this paper is to provide a brief overview of energy storage methods and to refer to the most convenient method for steam and CCGT professional units. This paper proposes an innovative steam storage which is an integral part of the steam cycle and thus responds quickly to changes in electricity demand and therefore can improve the provision of primary regulation service while maintaining high energy conversion efficiency. With regard to commercial power units, it improves the operational safety of generation units by preventing thermal overloads of boilers, HRSG and turbines in the event of high power output or in the event of sudden overruns. A steam plant and CCGT units adapted to rapid changes in power becomes more competitive in the power market by improving its dynamic behaviour.
Keywords: CCGT plant, flexibility operation, an innovative steam storage