Vertical Cylindrical Tank Research Articles

Experimental Analysis of Cavitation Erosion: Parameter Sensitivity and Testing Protocols

The scientific goal of this study was to investigate the effects of various parameters on cavitation-induced erosion, with the aim to enhance the understanding and assessment of cavitation resistance in hydraulic systems. Cavitation erosion poses significant challenges to the durability and efficiency of hydraulic components, such as those found in hydropower plants and pumping stations. Prompted by the need to improve the reliability of cavitation testing and material assessment, this research conducted a comprehensive sensitivity analysis of a cavitation jet apparatus (CJA). This study employed an experimental platform that consisted of a vertical cylindrical test tank, a submerged nozzle, and an aluminum sample. By examining a range of orifice diameters, this research identified that smaller diameters led to increased erosion intensity, with the most pronounced effects observed at a diameter of 2 mm. Furthermore, various standoff distances (SoDs) were tested, which revealed that shorter distances resulted in greater erosion, with the highest impact noted at an SoD of 5 cm. This study also evaluated different nozzle geometries, where it was found that a 132° conical sharped edges nozzle, combined with an orifice diameter of 2 mm and an SoD of 5 cm, produced the most severe erosion. Conversely, chamfered edges nozzles and a commercial nozzle (MEG2510) with an SoD of 10 cm or greater showed reduced erosion. These results highlight that by standardizing the testing duration to 1200 s, the CJA could reliably assess the cavitation resistance of materials. This study established a clear relationship between increased pressure and higher impact forces, which led to more severe erosion. The findings underscore the effectiveness of the CJA in evaluating material resistance under various cavitation conditions, thus addressing a critical need for reliable cavitation testing tools.

Mathematical model of the process of mixing semi-liquid feeds in a device with a propeller

The article considers the issues of using a propeller apparatus for mixing semi-liquid feed mixtures in a mixer with an eccentrically positioned working body in the form of a propeller (screw). Until now, when studying the mixing process, little attention has been paid to the transporting ability of the working body in the form of a propeller agitator. When preparing wet mixtures, agitators with a vertically positioned shaft, which is located in the center of a vertical cylindrical tank, are widely used. When installing the working body horizontally, the propeller having a pumping effect (axial movement), can be used not only for mixing, but also for unloading the finished feed mixture, as well as moving it through pipes over short distances. The existing models of the mixing process do not take into account its stochastic nature. Methods of mathematical description of mixing processes considering the prevailing axial movement of the flow are scarcely developed. The proposed mathematical models make it possible to determine the mixer's performance and the required mixing power. The research was aimed at increasing the effectiveness of preparing a feed mixture in a horizontal mixer of propeller type with an eccentrically positioned working body (screw) and saving energy costs along with raising the productivity. The object of the study was a mixing chamber with eccentrically located working bodies of various diameters (0.2, 0.25 and 0.35 m). During the experiments, the productivity required to drive the motor shaft was determined. It has been experimentally established that increasing the agitator rotation speed from 200 to 400 min-1 with a propeller diameter from 0.2 to 0.35 m and a feed mixture humidity of 84 % leads to an increase in power consumption to 3.5 kW and mixer productivity to 12 m3/h, and the degree of uniformity of feed mixtures is up to 98 %.

Waste heat utilisation during moulding sand reclamation process

The paper presents research to develop a complete system for recovering, storing and utilising the thermal energy of the knocked-out moulding sand. The cooling of the moulding sand is slow and, therefore, moulding sand cannot be used in a regeneration station and returned to the foundry process quickly. The moulding sand cooling process can be accelerated, and the recovered heat can be used in other energy-intensive processes in the foundry. As for now, the heat recovery methods or the ways of the heat further use are unknown. This paper presents the concept of a heat recovery system that allows to utilise the heat contained in moulding sand knocked out of large moulds at temperatures between 350 and 400 °C. The permissible moulding sand temperature at the inlet to the regeneration station should not exceed 90 °C. It is assumed that the moulding sand will be cooled with water in two vertical cylindrical tanks where heat exchangers with finned tubes will be placed. Using numerical modelling, the design of a heat exchanger for moulding sand cooling was selected. The capacity of the developed heat exchanger is 600 kW. Numerical analyses and experimental tests confirmed that the heat exchanger can absorb all the heat from the moulding compound and cool it down to 90 °C within 6 h. Implementing the developed system will reduce the foundry's CO2 emissions by 329 tonnes annually.

EXPERIMENTAL EVALUATION OF THE STRUCTURAL INTEGRITY OF VERTICAL CYLINDRICAL STORAGE TANK SHELL-TO-BOTTOM JOINTS OF VARIOUS DESIGNS

Bottom-to-shell joint is one of the most critical areas in vertical cylindrical storage tanks, both in terms of the number of detected flaws and the causes of failures. The primary factors contributing to the present state include the structural peculiarities of the shell-to-bottom joint, leading to incomplete fusion in the middle between the double filletgroove welds (double fillet welds) and, consequently, low inspectability. This results in a complex stress-strain state with maximum stress levels in the area of the shell-to-bottom joint. Thus, improving the existing design of the bottom-to-shell joint is relevant.This article presents the results of comparative resource evaluation tests conducted on the typical design of the shell-to-bottom joint and two prospective designs: one with complete penetration weld and another with a T-section. The tests were conducted using prototypes that replicate the necessary structural properties of the shell-to-bottom joint and the stress distribution diagram, allowing testing on standard servo-hydraulic machines. The results obtained indicate that all considered designs of shell-to-bottom joints, when free from flaws, exhibit high reliability, ensuring safe operation even under double the operational stresses for a minimum of 50 years. Considering the improved inspectability and feasibility of manufacturing these prospective shell-to-bottom joint designs, along with their comparable production costs, they can be recommended for practical applications.

MODERNIZATION OF BOTTOM SEDIMENT SCOURING PROCESS IN RVSP 20000 TANKS

According to the existing norms a tank should be necessarily taken out of operation once in 8-10 years for diagnostic works. The most labor-intensive part is removal of paraffin deposits from its bottom. In this regard, the main purpose of the study is to study the technology of the process of scouring bottom sediments in steel vertical cylindrical tanks with a pontoon volume of 20000 m3 (RVSP 20000) and modeling the operation of various cleaning devices to determine the most effective of them.
 The RVSP 20000 tank includes a device for bottom sediment scouring «DIOGEN-700». In the process of its operation under the action of the rotating blade of the propeller a jet of liquid is created, which mixes oil in the tank due to circular movement of streams. The greatest ac- cumulation of paraffin trace is observed in the-near-wall zone of the tank, therefore there is a need to find a new method of hydromechanical prevention of sludge accumulation on the bottoms of oil tanks.
 As the main device for bottom cleaning it is proposed to use a stirring jet device («UPS-EVNAT»). It divides one main stream into several equal parts. As a result, the area of sediment scouring is higher than when using standard equipment.
 In this work, the turbulent string flow with the use of screw agitator «DIOGEN-700» and with the use of «UPS-EVNAT» was modeled. The revealed results allow to assert that the application of agitating jet device allows to realize better quality erosion of paraffin deposits and cover a larger area in comparison with «DIOGEN-700».

Thermal performance of cylindrical and spherical liquid hydrogen tanks

In liquid hydrogen (LH2) storage tanks, the temperature difference between LH2 and the environment leads to the inevitable heat ingress into the storage tanks. Understanding the details of the thermal performance in LH2 storage tanks is necessary to minimize or avoid boil-off gas losses. This paper presents a thermodynamic non-equilibrium model to study the thermal differences between cylindrical and spherical LH2 tanks with the same volumetric capacity. The accuracy of the model is validated with experimental data obtained from cylindrical and spherical tanks. The numerical results show that, in self-pressurized tanks, a spherical geometry results in the lowest pressure increase rate. The pressure increase in horizontal, cylindrical tanks is slower than the corresponding increase in cylindrical tanks oriented vertically. The difference can be related to more effective heat transfer between the vapor and liquid phases in the horizontal cylindrical tanks. A higher initial liquid level increases the thermal mass of the liquid, which suppresses the evaporation rates due to larger heat requirements to warm and evaporate the liquid hydrogen. For tanks under atmospheric pressure, the boil-off gas rate is lowest in the spherical tank while the boil-off gas rates in the horizontal and vertical cylindrical tanks are almost the same. Under these conditions, and quasi-steady state, the total heat absorbed by the tanks is used to evaporate LH2. The spherical tank has the smallest surface area and thus the lowest evaporation rate and the lowest heat transfer from the environment. The evaporation rate is not affected by initial liquid levels.

Assessing Cavitation Erosion on Solid Surfaces Using a Cavitation Jet Apparatus

This study is dedicated to the examination of cavitation-induced erosion, a critical factor in optimizing the efficiency of hydraulic systems, including hydropower plants and pumping systems. To accomplish this, we conducted a sensitivity analysis utilizing a cavitation jet apparatus (CJA) and an experimental configuration that featured a vertical cylindrical test tank, a submerged nozzle, and an aluminum sample (specifically, alloy 6351 T6). The study maintained a consistent standoff distance of 5 cm and an orifice diameter of 2 × 10-3 m. Two distinct nozzle geometries were tested to assess their influence on cavitation erosion. The outcomes revealed that the 20° conical sharped-edges nozzle resulted in the highest erosion rates, while the commercial nozzle (MEG 2510) caused comparatively less erosion. By standardizing the test duration to 1200 seconds and using a cavitation index of 0.14, the researchers avoided overlapping pits. In summary, the CJA, with these adjustments, demonstrated its effectiveness as a tool for evaluating the resistance of solid surfaces to cavitation.

Comparative Analysis of the Mechanical Exploitation Properties of the Steel Sheet Welded Joint of New and Old Materials

The rehabilitation process of the war-damaged vertical cylindrical tank with a volume of 5.000 m3 located at the oil terminal for liquid cargo TTT S-105 Ribić in Bihać, included a preliminary experimental examination of the mechanical exploitation properties of the steel sheet welded joints. A new steel sheet Č.0361 was acquired for this purpose. In addition, a sample of an old sheet of the same quality was taken from the construction of the devastated tank, which had been in use for more than 35 years. The experimental testing should determine the mechanical exploitation properties of the new material, examine the same properties of the old used material, compare the obtained results and confirm their mutual acceptability in the joint construction. The tank in question was damaged as a result of direct or indirect missile hits during the war period. Following the more economically acceptable rehabilitation, compared to demolition and complete reconstruction, the tank should be returned to a safe and usable condition.

Influence of liquid viscosity on surface wave motion in a vertical cylindrical tank

In order to explore the influence of liquid viscosity on surface wave motion in offshore cylindrical oil storage tank, hundreds of sloshing experiments were conducted by using four white oils with different viscosities. The present study demonstrates that the excitation frequency and excitation amplitude as well as liquid viscosity have significant influence on sloshing behavior in the cylindrical tank subjected to harmonic horizontal excitation. For low-viscosity oil, when the excitation frequency is very close to or equal to the natural frequency of first asymmetric mode, swirling wave motion with or without breaking can be observed. In addition, it is interesting to note that the sloshing behavior at the second-mode resonant condition is more complicated than that at the first-mode resonant condition, owing to the adjacent asymmetric modes are excited by various nonlinear effects. With the increase of oil viscosity, the surface wave motion becomes more and more stable with smaller wave amplitude and simpler wave pattern. To the best of the author's knowledge, this is the first case of systematic study of sloshing behavior of liquid with different viscosity in the vertical cylindrical tank. The experiments also provide accurate data for the calibration of theoretical and numerical models.

Evaluation of the potential use of thermotolerant lignocellulolytic Streptomyces thermocarboxydus ME742 and the mutant MEEMS15-16 as inoculum for effective composting of wastes from palm oil mill

Composting is a potential option for managing the large amount of waste from a palm oil mill, including empty fruit bunches (EFB) and decanter cake (DC). In this study, Streptomyces thermocarboxydus ME742 (WTME742) and its mutant MEEMS15-16 were used as lignocellulotytic inoculum to compost mixed EFB and DC (1:1) in a vertical cylindrical tank with moisture content maintained in the range of 50–70% for 40 days. Their effects were compared to microbial activators (LDD.1). In composting system, MEEMS15-16 showed rapid production for high cellulase (3.86 U/g) on day 3 with ability to sustain high lignin peroxidase over mesophilic stage, while WTME742 produced highest xylanase (11.07 U/g) and manganese peroxidase (100 U/g). After day 40, nutrient contents in all the composts met quality standard requirements of compost, except for the un-inoculated control. WTME742 provided a high nitrogen content (N:P:K was 1.72:1.21:2.35) with a considerably low C/N ratio (12.19) whereas MEEMS15-16 gave higher potassium content (N:P:K was 1.46:1.10:2.52) with a lower C/N ratio (11.09). Co-inoculum with LDD.1 also showed the promising results. Regarding spectral analyses (FTIR and XRD), MEEMS15-16 showed the greater ability for lignocellulosic matter transformation and composting using co-inoculum of MEEMS15-16 or WTME742 with LDD.1 provided high humification degree. The findings demonstrated the potential for use of WTME742 and MEEMS15-16 as inoculant in either single culture or the co-culture with LDD.1. These microbial inoculants would serve as the driving forces in facilitating degradation of palm oil mill wastes, and consequently enhancing the feasibility of compost production at industrial scale.

Experimental investigation of three-dimensional free-surface and interfacial sloshing in a vertical cylindrical tank

In the present study, hundreds of experiments have been conducted on the three-dimensional free-surface and interfacial sloshing in a vertical cylindrical tank containing two immiscible liquids. The bounds of different free-surface and interfacial wave regimes are determined by maintaining fixed excitation amplitude and slowly increasing excitation frequency until another type of wave regime began to appear. In general, three types of the free-surface wave regimes are observed when the excitation frequency is in the neighborhood of the lowest natural frequency of the free surface, i.e., planar gravity wave, chaotic gravity wave, and swirling gravity wave. Similarly, when the excitation frequency is near the lowest natural frequency of the internal interface, three types of interfacial wave regimes, i.e., planar gravity wave, chaotic gravity-capillary wave, and swirling gravity-capillary wave, are generated. Besides, it is worth pointing out that when the excitation frequency is near the lowest natural frequency of the internal interface as well as very close to a third of the lowest natural frequency of the free surface, large-amplitude rotating wave motion occurs at both the free surface and the internal interface. This is due to even though the excitation frequency is far away from the natural frequency of the free surface, the secondary resonance can still become dominant and lead to large-amplitude motion of the free-surface rotating wave and subsequently influences the internal interface. This paper reveals that the sloshing behaviors of two-layer liquid in the vertical cylindrical tank are much more complicated than those of single-layer liquid.

Tanques de armazenamento cilindricos e atmosféricos: otimização de projeto considerando critérios ambientais

Atmospheric tank projects cover a wide range of technical characteristics, ranging from their purpose, according to the regulatory framework, the type of product stored, the technical aspects of the tank to serve this storage with structural safety, and finally, the devices and technical resources to make the equipment financially and economically viable and sustainable. As a basis for criteria for this assessment, the correct regulatory framework for each type of tank, based on its application, and the correct selection of material for its performance and life expectancy, were addressed. Performance improvement criteria were also evaluated, such as the proper sizing of the tank inlet, outlet, and vent nozzles, the use of sensors and devices, and equipment to avoid overpressure or vacuum, and the use of internal floating roofs. In addition, environmental criteria were also presented, such as the correct selection of tank colors and the assessment of their area of ​​incidence of solar radiation. The list of criteria and technical, performance, and environmental details can be further complemented and developed with other characteristics of the tanks, and the objective of this article was to evaluate the main parameters of analysis to guide the developer of the tank project to execute it seeking to optimize technical data with immediate execution and operating costs and the environmental impact of project decisions for welded vertical cylindrical atmospheric storage tanks.

Laboratory Investigation of the Dynamic Response of a Prestressed Composite Steel Cylindrical Tank Subjected to Horizontal Loading

In this article, a laboratory investigation on prestressed composite steel cylindrical tanks is performed at different prestressing parameter values (coil span, thickness, and prestressing force). Natural vibration frequencies of a traditional tank and a prestressed composite tank were determined at different filling levels. The research results reveal that prestressing using a steel wire strand has a positive effect in terms of the value of the attenuation coefficient where, when comparing a traditional tank with a coiled tank with a coil span equal to a = 3d, the attenuation coefficient changes in a positive direction by 22.9%; whereas, when comparing a traditional tank with that with a coil span equal to a = d, then the positive effect reaches up to 33%. The value of the attenuation coefficient of a half-filled tank shows that prestressing improves the attenuation coefficient at a coil span equal to a = 3d and up to 8.7%, and with a coil span equal to a = d, up to 26%. Conversely, in the analyses of the tank specimen filled up to the maximum level, the attenuation coefficient changes in a positive direction with a coil span equal to a = 3d, up to 15%, and when accounting for a coil span equal to a = d, up to 35%. In general, the effect of the use of prestressing in terms of the attenuation coefficient shows a positive trend between a percentage range of 8.7 and 35%, depending on the liquid filling conditions, and the vibration amplitudes decrease in a percentage range of 3.8–20%, also depending on the coil span and filling conditions of the tank. The obtained laboratory results positively expand the investigations performed within this research field. As a result, the corresponding findings can be used for the construction and design phases of vertical steel cylindrical tanks.

Seismic analysis of a soil-liquid tank system using MATLAB Simulink

In this paper, a model is proposed for analyzing the long-term responses of a liquid tank system to earthquake loads while taking soil interaction into account. Three degrees of freedom (DOFs) in the sway-rocking form and the monkey tail DOF are used to model the soil-foundation system, while the fluid in the tank is modeled as a 2-DOF lumped parameter using the substructure method. By using the MATLAB Simulink tool to numerically integrate the system of differential equations of motion, the response of the DOFs, shear force, and moment at the tank bottom can be tracked over time. The El Centro 1940 earthquake's acceleration excited a vertical cylindrical tank with a radius of 10 m and a water mass of 8 m; the results of the analysis show that the horizontal displacement of the convective mass increased by 16.36%, and the shear force and moment significantly increased in comparison to the case of the tank rigidly linked to the ground.

Analysis and design of a vertical sectored tank

AbstractThis article describes the conceptual design and the structural analysis of a vertical cylindrical partitioned tank for an international chemical company. Vertical cylindrical tanks are commonly used in the chemical industry worldwide as vessels to contain liquids. Most of these plants have reduced area for the installation of the container tanks. Many of them need to renew their manufacturing process according to the new technologies and requirements. In addition, in some cases, the preparation of mixtures is carried out on small surfaces. All this factors led to the idea of designing a vertical sectorised tank, considering that alternative hydrostatic pressure cases can lead to eccentric loads on the upper surfaces. Therefore, bending stresses and compression and tension stresses will occur. A Finite Element Method calculation was performed to determine the wall thickness fulfilling the structural requirements for two distinguishing design alternatives. This article describes the particular models designed and the detailed FEM simulation and mechanical calculation carried out to determine the optimized solution of partitioned tanks with a diamond‐shaped inner bracing system that manages to meet all the structural, manufacturing, constructive and environmental needs with a target thickness of 12 mm.

Measurement of strain and determination of stress state using a multi-chamber vertical cylindrical tank model

Designing a new construction of large-volume multi-chamber tanks or converting existing single-chamber tanks into multi-chamber for storage of various types of petroleum products is a very demanding and responsible job, from the aspect of strain-stress analysis and the need to ensure structural integrity. From a wide range of conducted theoretical and experimental-numerical research, this paper singles out the applied method of similarity mechanics. The research was performed on a model of a four-chamber tank with dimensions reduced by 20 times (1:20) in relation to the real tank, made of steel sheets of quality S.0361. During the cold-water pressure test on the tank model (hydro test), the change of strain and stress state was monitored in the zones that were defined as critical by the preliminary numerical analysis by the finite element method (FEM). The results of these measurements, along with other reliable methods, can be very useful in the design of multi-chamber tanks with 5.000 m3 volume.

Oscillation frequencies of the reinforced wall of a steel vertical cylindrical tank for petroleum products depending on winding pre-tension

This paper reports a study of the frequencies and vibration modes of a vertical steel tank with a variable wall thickness in the ANSYS software suite using a finite-element model of vibrations of a tank with a volume of 3000 m3 for oil and petroleum products, hardened by a prestressed winding. The simulation was carried out for two variants of fixing the upper edge of the tank wall, which correspond to cases of absence or presence of tank coating. The estimation cases for the coefficients of the tension force of the wire relative to its tensile strength were investigated: at k1=0.2; k2=0.4; k3=0.6 and k4=0.8. Variation studies were carried out both taking into account the additional loads caused by the action of hydrostatic pressure from the maximum and half poured oil into the tank, and without oil. The magnitude of changes in the vibration frequencies of the tank wall without the influence of the coating varies within 12–27 % and when taking into account the influence of tank coating, 21–62 %, depending on the degree of filling of the tank. The revealed pattern relates to the fact that a decrease in the tension force of the filament in the winding leads to an increase in the frequency of oscillations. Thus, pre-stress can be applied to regulate the oscillation frequency of the tank wall. By decreasing which in the winding, it is possible to increase the natural frequencies of the wall and to lower the frequencies through an increase in the prestress. The research results can be used in the future as anti-seismic measures in the design and construction of steel vertical cylindrical tanks, as well as to improve the strength characteristics of existing cylindrical structures

Analysis of strength and eigenfrequencies of a steel vertical cylindrical tank without liquid, reinforced by a plain composite thread

A study of the effect of a plain composite wrapping on the stress-strain state of the wall of a steel cylindrical tank is proposed, without taking into account the liquid. The stress assessment in the tank wall was carried out based on finite element modeling of the structure’s three-dimensional model deformation. Two tank wall variants were modeled: with constant and variable thickness, as well as three wrapping variants: with one, double and triple intervals, where the mechanical characteristics of the tank thread and material of different types were considered, taking into account the oil filling level, the wrapping pitch and the thread’s mechanical characteristics. It turned out that the maximum equivalent stresses of an empty traditional tank of continuous thickness are 35 % higher than the stresses of a tank with variable thickness. At that, the equivalent stress index of a prestressed tank with variable wall thickness is 13 % higher than of a tank with constant wall thickness in all three cases of winding a plain composite thread. It should be noted that with an increase in the winding pitch, the equivalent stresses of the prestressed tank decrease by 1.5 times, in the case of winding 1:1 and 1:2. When considering the case of 1:1 and 1:3, the stresses decrease by 2 times, in the case of 1:2 and 1:3, the stresses decrease by 1.35 times. In the modal analysis of the tank with continuous and variable wall thickness without liquid, the first 60 eigenfrequencies were obtained. An analysis of the spectrum of eigenfrequencies and their corresponding eigenvibrations for two models of the tank without liquid showed that the eigenfrequencies of the traditional empty tank are 2–7 % less than the tank with prestressing. However, it was determined that a decrease in the tank wall thickness at the upper free edge from 5 mm to 4 mm does not result in changes in the number of nodes in the circumferential direction. The results obtained will allow to effectively use the prestressing in order to improve the strength and dynamic characteristics to avoid the resonance effect in the structures under study, taking into account the wrapping of a plain composite thread.

Thermal characteristics of melting of a phase change material enhanced by a stainless-steel 304 periodic structure

In this work, melting of a high-temperature inorganic phase change material (PCM) eutectic (with a melting point of 569 °C) within a vertical cylindrical tank has been experimentally investigated. To promote the heat transfer rate, a periodic structure that is constructed by a commercial SS-304 mesh screen has been considered and immersed into the PCM tank. Thermal characteristics of the PCM-periodic structure tank under different initial temperatures (450, 490 and 546 °C) and wall temperatures (620, 640, 660, 680 and 700 °C), are then investigated and reported. The presented experimental data can facilitate practical engineers to find the best operating condition of similar PCM tanks; meanwhile, it can also be employed for the investigation of thermal response of transient heat conduction before melting starts.

Actual work’s numerical analysis for support joint of vertical cylindrical tank

The article describes the actual work’s numerical analysis for unit joining walls to the bottom of vertical cylindrical tank of 50 thousand m3. Having analyzed the relevant stress-strain state of unit joining walls to the bottom vertical cylindrical tanks for different types of finite element model. Research carried out for the tank with a wall on a rigid base. Features of the unit joining walls to the bottom should include the effect of various loads: static, dynamic, cyclic, corresponding to normal operation. The load on the pressure of the liquid taken appropriate normal operation. Presented and analyzed the main results of numerical studies and get a picture of the stress-strain state of unit joining walls to the bottom vertical cylindrical tank of 50 thousand m3 for different types of finite element model.