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Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 492
Author(s):  
Karlo Petrović ◽  
Antonio Petošić ◽  
Tomislav Župan

In this work, the vibrations on the surfaces of the tank wall, stiffeners, and the cover of a 5 MVA transformer experimental model were measured during open-circuit and short-circuit transformer tests. Vibration measurements of a transformer tank side were conducted at discrete points using two different voltage sources in no-load test. Using interpolation functions, the RMS values of acceleration and vibration velocity are visualized and compared for each considered measurement configuration (no-load and load tests and two different excitation sources). Significant differences in mode shapes and amplitudes of vibrations at different frequencies are observed. The maximum RMS values of acceleration, velocity and displacement in the open-circuit test are 0.36 m/s2, 0.31 mm/s, and 0.42 µm, respectively. The maximum values in short-circuit test are 0.74 m/s2, 1.14 mm/s, and 1.8 µm, respectively. In the short-circuit test, the frequency component of 100 Hz is dominant. In the open-circuit test, the first few 100 Hz harmonics are significant (100 Hz, 200 Hz, and 300 Hz). In addition to the visualization of RMS values during the open-circuit and short-circuit tests, animations of the vibrations are created. Fourier analysis and phase comparison between frequency components are also used to show vibration animations at dominant frequencies in the spectrum (100 Hz harmonics). The visualization of the vibrations at the tank wall surfaces is transferred into 3D space in such a way that all 15 surfaces are mapped to the spatial coordinates of the surfaces so that a 3D model of the acceleration, vibration velocity, and displacement of the transformer tank is shown.


2021 ◽  
Vol 1 (3) ◽  
pp. 39-47
Author(s):  
Sulistiana Agung Riyanto ◽  
Vidya Rina Wulandari ◽  
Bagas Putra Arfyansyah

Explosions and fires that occurred in the blending/mixing tanks of fuel with naphtha to produce pertalite type fuel were initiated by a leak in the tank wall. Based on the results of observations, inspections and tests that have been carried out, the leak of the tank which is the cause of the explosion and fire is the result of the reaction of the tank wall in the weld joint area with base metal (HAZ) which is susceptible to corrosion with acidic tank fluid contents (pH- 5) so as to form an acidic and corrosive environment in the tank with the formation of H2S as a corrosion initiator, reinforced by the discovery of corrosion products in the form of MnS, FeS2, and FeS compounds, elements (S), and the appearance of fractography in the form of white dots indicating uniform corrosion if it occurs for a long time can erode the tank wall and form a leak hole.


Author(s):  
Сергей Николаевич Морозов ◽  
Вадим Вячеславович Таганов ◽  
Дмитрий Викторович Калачинский ◽  
Дмитрий Анатольевич Иванченко

Установки водяного охлаждения резервуаров являются частью системы автоматического пожаротушения резервуарного парка и представляют собой комплекс устройств, оборудования и трубопроводов. Непосредственное охлаждение стенки резервуара осуществляется через верхнее горизонтальное кольцо орошения, выполненное в виде перфорированного трубопровода или трубопровода с оросителями. При этом до настоящего времени не была определена зависимость фактически защищаемой площади стенки от расходов воды, подаваемой через отверстия и/или оросители при их различном положении по отношению к стенке и верхней кромке резервуара. Цель исследования - экспериментальное определение оптимальных конструктивных и технологических решений элементов установок водяного охлаждения резервуара. Для изучения процессов теплового нагрева и охлаждения боковой поверхности резервуара проведены гидравлические и огневые испытания моделей секции установки водяного охлаждения - горизонтального кольца орошения. По результатам испытаний определена эффективность различных конструкций в зависимости от изменяемых технологических параметров (давления и расхода воды в кольце орошения), диаметра отверстий перфорированного трубопровода и шага между ними, угла расположения устройств подачи воды относительно горизонтальной поверхности сечения резервуара, расстояния от кольца орошения до стенки резервуара и его верхней кромки. Water cooling units for tanks are a part of automatic fire extinguishing system of the tank farm and represent a complex of units, equipment and pipelines. Tank wall is cooled down directly through upper horizontal spray distribution ring, made in the form of a perforated pipeline or a pipeline with sprinklers. With this, correlation between actually protected area of the wall and flow rate of water supplied through the holes and/or sprinklers at their different positions in relation to the wall and the upper edge of the tank, has not been determined so far. The purpose of the study is to experimentally determine the optimal design and technological solutions of the elements of tank water cooling units. To study the processes of thermal heating and cooling of the side surface of the tank, hydraulic and fire tests of models of the section of the water cooling unit (the horizontal spray distribution ring) were carried out. According to the test results, the efficiency of various structures was determined depending on the technological parameters being changed (pressure and water flow in the spray distribution ring), diameter of the holes of the perforated pipeline and pitch between them, angle of the water supply units relative to the horizontal surface of the tank section, distance from the spray distribution ring to the tank wall and its upper edge.


2021 ◽  
Author(s):  
Jun Zheng Chen

In this thesis, the dynamic response of concrete rectangular liquid storage tanks is investigated. In previous studies, the tank wall has been assumed as rigid in the calculation of hydrodynamic pressures. The effect of flexibility of tank wall is considered in this study. The analytical solutions for both impulsive pressure and convective pressure induced by both horizontal and vertical ground motions are presented. A 2-D coupled analysis model of tank wall is proposed. The hydrodynamic pressures are considered as external forces applied on the tank wall. Through a technique called the sequential method, the two fields of fluid and structure are coupled. The time-history analysis using the mode superposition method and the direct step-by-step integration method are carried out. Two rectangular tanks are analyzed. From the comparison of the results obtained from the proposed model with those proposed by other researchers, such as added mass model based on the rigid wall boundary condition, it shows that the lumped mass approach overestimates the base shear and wall displacement. The effect of wall flexibility on displacements, base shears and base moments are also discussed. A combination of the added mass method and the sequential method is used to study liquid storage tanks subjected to the vertical ground motion. It is found that the effect of the vertical acceleration should be considered in dynamic analysis of rectangular tanks. It is concluded that the total response of the structures should be based on the sum of the response under both horizontal and vertical components of ground motion.


2021 ◽  
Author(s):  
Jun Zheng Chen

In this thesis, the dynamic response of concrete rectangular liquid storage tanks is investigated. In previous studies, the tank wall has been assumed as rigid in the calculation of hydrodynamic pressures. The effect of flexibility of tank wall is considered in this study. The analytical solutions for both impulsive pressure and convective pressure induced by both horizontal and vertical ground motions are presented. A 2-D coupled analysis model of tank wall is proposed. The hydrodynamic pressures are considered as external forces applied on the tank wall. Through a technique called the sequential method, the two fields of fluid and structure are coupled. The time-history analysis using the mode superposition method and the direct step-by-step integration method are carried out. Two rectangular tanks are analyzed. From the comparison of the results obtained from the proposed model with those proposed by other researchers, such as added mass model based on the rigid wall boundary condition, it shows that the lumped mass approach overestimates the base shear and wall displacement. The effect of wall flexibility on displacements, base shears and base moments are also discussed. A combination of the added mass method and the sequential method is used to study liquid storage tanks subjected to the vertical ground motion. It is found that the effect of the vertical acceleration should be considered in dynamic analysis of rectangular tanks. It is concluded that the total response of the structures should be based on the sum of the response under both horizontal and vertical components of ground motion.


2021 ◽  
Author(s):  
Jun Zheng Chen

Liquid storage tanks are essential facilities in lifeline and industrial systems. To ensure liquid tightness, serviceability is the prime design concern for these structures. While there have been major studies on the behavior of steel tanks, little attention has been paid to the behavior of rectangular concrete tanks. In this study, the dynamic response of concrete rectangular liquid storage tanks is investigated. In the current design practice, the response of liquid and tank structure is determined based on rigid tank wall and the lumped mass approach. However, the results of analysis show that the flexibility of tank wall increases the hydrodynamic pressures as compared to the rigid wall assumption. Also, recent studies show that the lumped added mass method leads to overly conservative results in terms of base shear and base moment. In addition, in spite of advanced analysis techniques available for dynamic analysis of liquid storage tanks such as finite element method and sequential coupling analysis procedure, there is a need to develop a simplified analysis method for practical applications. In this thesis, a simplified method using the generalized single degree of freedom (SDOF) system is proposed for seismic analysis of concrete rectangular liquid containing structures (LCS). Only the impulsive hydrodynamic pressure is considered. In the proposed method, the consistent mass approach and the effect of flexibility of tank wall on hydrodynamic pressures are considered. Different analytical methods are used to verify the proposed model in this study. The comparison of results based on the current design practice, the analytical-finite element models and full finite element model using ANSYS® shows that the proposed method is fairly accurate which can be used in the structural design of liquid containing structures. Parametric studies on seismic analysis of concrete rectangular LCS using the generalized SDOF system are carried out. Five prescribed vibration shape functions representing the first mode shape of fluid structure interaction system are used to study the effect of flexibility of tank wall and boundary conditions. The effect of flexibility of tank wall, the amplitude of hydrodynamic pressure, the added mass of liquid due to hydrodynamic pressure, the effective heights for liquid containing system and the effect of higher modes on dynamic response of LCS are investigated. In addition, the effect of variable size of tanks and liquid depth are studied. The contribution of higher modes to the dynamic response of LCS is included in the proposed model. A design procedure based on the structural model using the generalized SDOF system is proposed in this study. Design charts and tables for the added mass of liquid due to impulsive hydrodynamic pressure and the corresponding effective heights are presented. The proposed design procedure can be used for engineering design applications.


2021 ◽  
Author(s):  
Jun Zheng Chen

Liquid storage tanks are essential facilities in lifeline and industrial systems. To ensure liquid tightness, serviceability is the prime design concern for these structures. While there have been major studies on the behavior of steel tanks, little attention has been paid to the behavior of rectangular concrete tanks. In this study, the dynamic response of concrete rectangular liquid storage tanks is investigated. In the current design practice, the response of liquid and tank structure is determined based on rigid tank wall and the lumped mass approach. However, the results of analysis show that the flexibility of tank wall increases the hydrodynamic pressures as compared to the rigid wall assumption. Also, recent studies show that the lumped added mass method leads to overly conservative results in terms of base shear and base moment. In addition, in spite of advanced analysis techniques available for dynamic analysis of liquid storage tanks such as finite element method and sequential coupling analysis procedure, there is a need to develop a simplified analysis method for practical applications. In this thesis, a simplified method using the generalized single degree of freedom (SDOF) system is proposed for seismic analysis of concrete rectangular liquid containing structures (LCS). Only the impulsive hydrodynamic pressure is considered. In the proposed method, the consistent mass approach and the effect of flexibility of tank wall on hydrodynamic pressures are considered. Different analytical methods are used to verify the proposed model in this study. The comparison of results based on the current design practice, the analytical-finite element models and full finite element model using ANSYS® shows that the proposed method is fairly accurate which can be used in the structural design of liquid containing structures. Parametric studies on seismic analysis of concrete rectangular LCS using the generalized SDOF system are carried out. Five prescribed vibration shape functions representing the first mode shape of fluid structure interaction system are used to study the effect of flexibility of tank wall and boundary conditions. The effect of flexibility of tank wall, the amplitude of hydrodynamic pressure, the added mass of liquid due to hydrodynamic pressure, the effective heights for liquid containing system and the effect of higher modes on dynamic response of LCS are investigated. In addition, the effect of variable size of tanks and liquid depth are studied. The contribution of higher modes to the dynamic response of LCS is included in the proposed model. A design procedure based on the structural model using the generalized SDOF system is proposed in this study. Design charts and tables for the added mass of liquid due to impulsive hydrodynamic pressure and the corresponding effective heights are presented. The proposed design procedure can be used for engineering design applications.


2021 ◽  
Author(s):  
Mehdi Moslemi

In this study, the seismic performance of concrete ground-supported cylindrical as well as liquid-filled elevated water tanks supported on concrete shaft is evaluated using the finite element method. The effects of a wide spectrum of parameters such as liquid sloshing, tank wall flexibility, vertical ground acceleration, tank aspect ratio, base fixity, and earthquake frequency content on dynamic behaviour of such structures are examined. Furthermore, the adequacy of current practice in seismic analysis and design of liquid containing structures is investigated. A comprehensive parametric study covering a wide range of tank capacities and aspect ratios found in practice today is also carried out on elevated tanks. Two different innovative strategies to reduce the seismic response of elevated tanks are examined, in the first strategy the inclined cone angle of the lower portion of the vessel is increased while in the second strategy the supporting shaft structure is isolated either from the ground or the vessel mounted on top. The results of this study show that capability of the proposed finite element technique. Using this method, the major aspects in the fluid-structure interaction problems including wall flexibility, sloshing motion, damping properties of fluid domain, and the individual effects of impulsive and convective terms can be considered. The effects of tank wall flexibility, vertical ground acceleration, base fixity, and earthquake frequency content are found to be significant on the dynamic behaviour of liquid tanks. The parametric study indicates that the results can be utilized with high level of accuracy in seismic design applications for conical elevated tanks. This study further shows that increasing the cone angle of the vessel can result in a significant reduction in seismically induced forces of the tank, leading to an economical design of the shaft structure and the foundation system. It is also concluded that the application of passive control devices to conical elevated tanks offers a substantial benefit for the earthquake-resistant design of such structures.


2021 ◽  
Author(s):  
Mehdi Moslemi

In this study, the seismic performance of concrete ground-supported cylindrical as well as liquid-filled elevated water tanks supported on concrete shaft is evaluated using the finite element method. The effects of a wide spectrum of parameters such as liquid sloshing, tank wall flexibility, vertical ground acceleration, tank aspect ratio, base fixity, and earthquake frequency content on dynamic behaviour of such structures are examined. Furthermore, the adequacy of current practice in seismic analysis and design of liquid containing structures is investigated. A comprehensive parametric study covering a wide range of tank capacities and aspect ratios found in practice today is also carried out on elevated tanks. Two different innovative strategies to reduce the seismic response of elevated tanks are examined, in the first strategy the inclined cone angle of the lower portion of the vessel is increased while in the second strategy the supporting shaft structure is isolated either from the ground or the vessel mounted on top. The results of this study show that capability of the proposed finite element technique. Using this method, the major aspects in the fluid-structure interaction problems including wall flexibility, sloshing motion, damping properties of fluid domain, and the individual effects of impulsive and convective terms can be considered. The effects of tank wall flexibility, vertical ground acceleration, base fixity, and earthquake frequency content are found to be significant on the dynamic behaviour of liquid tanks. The parametric study indicates that the results can be utilized with high level of accuracy in seismic design applications for conical elevated tanks. This study further shows that increasing the cone angle of the vessel can result in a significant reduction in seismically induced forces of the tank, leading to an economical design of the shaft structure and the foundation system. It is also concluded that the application of passive control devices to conical elevated tanks offers a substantial benefit for the earthquake-resistant design of such structures.


Author(s):  
Abderrahim Mokhefi ◽  
Mohamed Bouanini ◽  
Mohammed Elmir ◽  
Pierre Spitéri

The enhancement of the heat transfer in the stirred tank is a much-desired objective for accelerating certain physical and chemical parameters in the industrial field. From this basis, an attempt is made in this paper to investigate the effect of the wavy wall of a stirred tank on the hydrodynamic, thermal, and energetic behavior of an Al2O3-Water nanofluid. The stirred tank has a flat bottom, and it is equipped with an anchor stirrer. A hot temperature has been imposed on the tank wall, and the agitator has been assumed adiabatic, where the nanofluid has a cold temperature at the initial instant. The laminar flow was governed by the equations that describe the forced convection, and it was solved by the finite element method. The numerical simulation results showed a considerable acceleration in the heat transfer inside the stirred tank by increasing the amplitude of the wavy wall and increasing the nanoparticle concentration. However, there has been a remarkable increase in the stirring power number. This contribution aims to increase thermal efficiency, especially in the chemical and petrochemical fields, to obtain a better yield of certain chemical reactions and mass transfer depending on the heat.


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