Cylindrical Storage Tanks Research Articles

Numerical investigation of hydrogen vapor cloud explosion from a conceptual offshore hydrogen production platform

Offshore hydrogen production platforms have the potential to become significant components in the upcoming large-scale offshore hydrogen production, contributing to the global commitment to carbon neutrality. However, the risk of hydrogen leaks is inherent, and the ignition of released flammable mixture can lead to catastrophic explosion, endangering both structures and nearby personnel. This study aims to numerically investigate the hydrogen vapor cloud explosion from offshore hydrogen production platform. The solvers published within the OpenFOAM framework are validated against two public tests involving hydrogen gas explosions within obstacles. A numerical model of the hydrogen vapor cloud explosion from a conceptual offshore hydrogen production platform is then constructed. The effect of offshore facility layout configuration on flame propagation mechanism and overpressure characteristics is analyzed. Results indicate that the presence of compressor equipment and cylindrical hydrogen storage tank leads to accelerated flame propagation and higher overpressure peaks. By reducing the cross-sectional area of the compressor equipment by 68% perpendicular to the flame propagation direction, the maximum flame propagation speed and overpressure are reduced by 88.6% and 94.2%, respectively. With an appropriate layout that maintains a cross-sectional area of 0.008, the presence of compressor equipment may not exacerbate the consequences compared to scenarios without any compressor equipment. This study provides a foundational basis for the safety design of offshore hydrogen production platforms, aiming to mitigate potential hydrogen explosion hazards.

A study on the small failure probabilities of cylindrical composite hydrogen storage tanks using subset simulation

Although composite hydrogen tanks are becoming increasingly intriguing, a detailed structural reliability analysis is still lacking. The current landscape of analysis for pressurised multilayer cylinders, while rich in research, lacks tools to deal with the low probabilities of failure that govern the design of hydrogen tanks. This study presents a computational framework integrating the Subset Simulation method (SS) for assessing the failure probability of composite tanks used for hydrogen storage. To explore how randomness impacts design parameters, this study utilises a limit state equation derived from the thin-walled circumferential model of composite pressure tanks. Five random variables, each with varying coefficients of variation (COVs), are incorporated into the analysis. For comparison and validation purposes, two methods Monte Carlo simulations and FORM have been used. The analysis revealed that SS excels at estimating the low failure probabilities of composite hydrogen tanks, and showed also the feasibility and accuracy of SS in the prediction of burst pressure since good agreement was obtained between the probabilistic approach and the experimental results. Furthermore, the uncertainties related to internal pressure and composite thickness affect significantly the reliability of the structure and can lead to the shrinkage of the safety margin and the failure of the vessel.

Seismic assessment of cylindrical storage tanks to records with different frequency contents considering fluid–structure–soil/foundation interaction

This study aims to primarily assess the dynamic behavior of ground-supported cylindrical tanks to real near-fault earthquake records with different frequency contents including soil-structure interaction effects. A cylindrical tank’s fluid-tank-soil interaction is modeled using a three-degree-of-freedom lumped mass model for the fluid. A mass-spring-dashpot model with frequency independence is used to model the soil/foundation system. Broad, medium, and slender tank models are developed considering and ignoring the soil flexibility effect. An algorithm based on discrete-time state-space approaches is developed for performing numerical simulations of the modeled tanks excited by the low-, medium-, and high-frequency contents. The obtained results for the modeled tanks in terms of base shear, overturning moment, and connective and impulsive mass displacements incorporating the influence of supporting soils as well as the frequency contents of excitation records are evaluated and compared with the corresponding results for modeled tanks with a fixed base. In addition, the liquid sloshing height for all aspect ratios is also evaluated and compared. The study’s findings clearly indicate that records with low-frequency contents require significantly more seismically demanding than other records for the considered soil types. Remarkably, soil-tank interaction under earthquake motions substantially amplifies the induced response.

Silica Aerogel-Modified Polyacrylonitrile Nanofibers to Reduce Heat Flux in Heat Storage Tanks of Greenhouse Buildings.

Polyacrylonitrile (PAN) nanofibers have specific characteristics such as thermal insulation, weatherproofing, and sunlight resistance and therefore are appropriate to be applied as insulation materials for various industries, especially in greenhouse construction. The heat source in greenhouse buildings that operate independently in the heating network comes from heat storage tanks. In the present study, employing thermal field numerical simulations, we investigate the heat flux of a cylindrical heat storage tank with silica aerogel-modified PAN nanofibers as thermal insulation materials. The geometric scale of the tank body, thermal insulation material thickness, and outdoor temperature are optimized to improve thermal insulation. The significant discrepancy in heat flux at different parts of the heat storage tank leads to the extreme heat flux arising at the water-gas interface on the inner and outer walls. It is indicated that the heat flux distribution can be effectively ameliorated by modifying the scale of the tank body to retain the overall water temperature. In particular, effective insulation can merely be acquired when the thermal conductivity of the insulation material is below 3.3 W·m-1·K-1. Eventually, the heat storage tank is optimized to store 1400 L water at 100 °C with a radius of 0.6 m and a thermal insulation thickness of 50 mm at an outdoor temperature of -10 °C, which can maintain excellent thermal insulation for 8 and 24 h at 87.7 and 69.9 °C, respectively.

Seismic vulnerability assessment of spherical and horizontal-cylindrical storage tanks through finite element analyses and observational data

Storage tanks are structures widely employed in various chemical and petroleum industries for the storage of liquids and gases. These structures, which store flammable and explosive substances, can lead to events such as fire and explosion in the event of any hazardous situation. Such accidents can have adverse effects on human life, facilities, the economy, and the environment. Earthquakes, as a natural threat affecting all structures, also trigger events like fire and explosion in storage tanks. Therefore, the assessment of seismic risks for storage tanks, the prediction of damage, is crucial for both existing and newly constructed tanks. In this study, the seismic behaviors of spherical and horizontal cylindrical storage tanks were investigated based on observational and finite element analysis data. Fragility analyses of tanks were conducted considering several commonly used statistical approaches, and fragility curves were derived. By using fragility curves, the probability of structural damage due to earthquakes is observed as a function of ground motion parameters. These curves express the likelihood of reaching or exceeding a pre-determined damage state under seismic effects for the considered type of structure. They are developed to predict potential damage during earthquakes and are outputs of seismic risk assessments. Fragility curves are utilized as indicators to determine physical damage during both the main shock and lower-intensity aftershocks. They can provide insights into whether the structure can be reused after earthquakes. Additionally, they are employed to reduce economic losses and casualties in the face of seismic events. For these reasons, fragility curves are essential statistical tools for decision-making both before and after earthquakes.

Assessment of Buckling Failure in Oil Storage Tanks: Finite Element Simulation of Combined Internal and External Pressure Scenarios

Investigating the structural behaviour and buckling susceptibility of cylindrical oil storage tanks is crucial for ensuring their safe and reliable operation. In this study, the structural behaviour and buckling susceptibility of closed roof-top cylindrical oil storage tanks under combined internal and external pressure scenarios were investigated using the finite element analysis (FEA) technique. By utilizing the FEA technique, the combined effect of wind-induced pressure of 250 Pa, applied on the outer surface of the tank and internal pressure of 0.5 MPa, applied on the outer surface of the storage was analysed. The result reveals significant stress concentrations and deformation patterns, particularly on the windward side of the tank, thus, emphasizing the susceptibility of the storage tank to buckling under the specified operating conditions for both the filled and half-filled tank; with internal pressure emerging as the primary contributor to mechanical strain and deformation experienced in the tank, while the wind load plays a secondary but significant role in the deformation of the tank. The fe-safe predicted useful life shows that under the specified operating conditions, the filled storage tank will survive 1 429 hours (2 months) while the half-filled tank will survive 3 551 hours (5 months) before failure due to buckling. Thus, the useful life estimation results show the importance of varying oil levels and operating conditions in the structural assessments of storage tanks.

Liquid Sloshing in Soil-Supported Multiple Cylindrical Tanks Equipped with Baffle under Horizontal Excitation

The dynamic behavior of liquid storage tanks is one of the research issues about fluid–structure interaction problems. The analysis errors of the dynamics of multiple adjacent tanks can exist if neglecting soil–tank interaction since tanks are typically supported on flexible soil. In the present paper, the dynamics of a group of baffled cylindrical storage tanks supported on a circular surface foundation and undergoing horizontal excitation are analytically examined. For upper multiple tank–liquid–baffle subsystems, accurate solutions to the velocity potential for liquid sloshing are acquired according to the subdomain partition technique. A theoretical model is utilized to portray the continuous sloshing of each tank. For the soil–foundation subsystem, a lumped-parameter model is used to characterize the impacts of soil on upper-tank structures using Chebyshev complex polynomials that present the fitting results of horizontal, rocking, and coupling impedance functions. Then, a model of the soil–foundation–tank–liquid–baffle system is constructed on the basis of the substructure approach. The present sloshing frequencies, sloshing height, and hydrodynamic shear as well as the moment under rigid/soft soil foundations are compared to the available exact results and the numerical results to prove the validity of the present model. The error of the maximum sloshing height between the present and the numerical solutions is within 5.27%; the solution efficiency of system dynamics from the present model is 40–50 times faster than that from the ADINA model. A detailed parameter analysis of the dynamic characteristics and earthquake responses of the coupling system is presented. The research novelty is that an equivalent analytical model is presented, and it allows for investigating the dynamics of soil-supported multiple cylindrical tanks with a baffle, providing acceptable accuracy and high calculation efficiency.

Numerical investigation of blast loading effects on a thin-walled cylindrical steel storage tank

Cylindrical storage vessels with thin walls are extensively utilized across various industrial sectors, including oil, gas, and petrochemicals, serving as crucial repositories for substances relevant to these industries. However, their susceptibility to fire and explosions underscores the need for comprehensive understanding and mitigation strategies. Amidst the escalating frequency of subversive attacks, regional conflicts, and other destabilizing events, a thorough comprehension of blast loading dynamics becomes paramount. These imperatives are compounded by recent occurrences, notably the cataclysmic explosion at the Beirut port in 2020 and the conflagration at a chemical plant in Texas in 2019, which starkly emphasize the pressing necessity for enhanced safety protocols. Thin-walled structures are particularly vulnerable to explosions, making the prediction of their response crucial. This study focuses on developing a computational model tailored for a horizontally oriented, simply supported, thin-walled water storage tank, utilizing advanced Abaqus/Explicit software. The primary objective is to investigate the impact of water when exposed to the explosive load generated by a 50 kg-TNT detonation at a distance of 0.50 m. The novelty of this work lies in the integration of advanced computational techniques, including the use of ConWEP 2.0, a sophisticated software framework developed by the U.S. Army, which integrates established formulations outlined by Kingery and Bulmash, as well as the employment of the Jones-Wilkins-Lee (JWL) Equation-of-State (EOS) alongside a sophisticated Smoothed-Particle Hydrodynamics (SPH) technique. The results reveal a significant reduction in deformation and damage inflicted upon the storage tank when subjected to explosive forces, attributed to the presence of water. This crucial finding highlights the effectiveness of water inclusion in enhancing the structural resilience of these tanks against potentially catastrophic blasts, thereby providing valuable insights for improved safety and durability in industrial environments.

An Experimental Study of Three-Dimensional Separation Surface Sloshing in the Wet Storage Tank of a Floating Offshore Platform

In this work, in order to elucidate the three-dimensional (3D) resonant sloshing dynamics of the oil–water interface in an offshore cylindrical wet storage tank, a series of model experiments are conducted in a completely filled cylindrical tank containing two immiscible liquids. To begin with, a series of free damping tests are performed to experimentally determine the viscous damping rate of the system and to examine the corresponding theoretical solutions. Subsequently, the separation surface wave responses at a series of excitation frequencies including the natural frequencies of first five modes are examined. Finally, the rotary sloshing dynamics at the natural frequencies of the first and second natural modes are systematically explored. Interestingly, it is found that the separation surface rotary sloshing in a two-layer liquid system is much more intricate than one-layer liquid rotary sloshing due to the generation of multitudinous short waves in the long wave. As far as we know, this is the first investigation of 3D separation surface rotary wave motion in a two-layer liquid system without a free surface.

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.

Dynamic Response of A Group of Cylindrical Storage Tanks with Baffles Considering the Effect of Soil Foundation

Dynamic Response of A Group of Cylindrical Storage Tanks with Baffles Considering the Effect of Soil Foundation

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.

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.

Integration of a conical frustum PCM system for enhanced thermal energy storage in a diesel engine cogeneration system

An effective heat storage system was achieved by fabricating a 400-L cylindrical thermal energy storage (TES) tank equipped with 9 conical frustum containers. These conical frustum containers with PCM (CFC-PCM) contain paraffin wax in the upper third of the tank and water as the heat transfer fluid (HTF) in the circulation process. The TES tank was integrated with a 40 kW diesel generator, and experiments were conducted by operating the engine at six different loads. During the charging process, heat was recovered from the engine exhaust gases and jacket cooling water. The performance parameters were evaluated and reported based on the transient behavior of a hybrid sensible/latent TES tank under the charging process. The results showed that at 72.55% of the engine peak load, the energy utilization factor (EUF) and the exergy efficiency of the system were 91.17% and 81.22%, respectively. Although adding PCM to water only resulted in a 3% enhancement in heat storage capacity, it improved the durability of heat charging by providing thermal stratification and increasing charging efficiency compared to the reference state in some of the studied cases.

On the nonlinear dynamic analysis of annular baffled steel containers isolated by bearings

This paper focuses on numerically scrutinizing the simultaneous influences of the base-isolator devices and annular baffles on the dynamic behavior of a three-dimensional (3D) cylindrical water storage tank, considering anirrotationaland inviscidfluidundergoing smallvibrations. A coupled acoustic-structure finite element formulationis developed for the analysis of the nonlinear dynamic behavior of the thin-walleddeformable cylindrical tanksunder real ground excitations. The established FEM procedure is competent in assaying the precise three-dimensional behavior of the isolated ground-supported annular baffled containers, including the performance of laminated rubber-bearing isolation devices in frequency and time domains. Vibration characteristics of water sloshing inside the benchmark tank are investigated under five different earthquakes with long and short-period contents. Furthermore, the dynamic response components of the base shear force, base moment, hydrodynamic pressure, and bearing deformation of the isolation devices regarding some system parameters comprising lateral isolation and locations of baffle devices are quantified efficaciously. In conclusion, the numerical simulations in the time-domain revealed that satisfactory performance of the baffled liquid tanks might not be achieved by only relying on the first convective mode frequency of the tanks due to an unwanted increase of sloshing amplitudes in exceptional cases of liquid tank geometry and baffles; the baffles with smaller effects on the first convective modes were more effective on decreasing the sloshing wave amplitudes. Hence, in the case of slender tanks, it is recommended that a baffle geometry be selected for each earthquake frequency content and analyzed over time to obtain the best performance from the baffles, but for the broad tanks, a baffle selection independent of the earthquake frequency content might be acceptable. Also, the results indicate that in the board tanks, top-mounted baffles amplify the seismic response of the system; thus, remarkable attention would be required in using baffles in such tanks; therefore, it has been recommended to use mid-mounted baffles in these tanks.

NUMERICAL ANALYSIS OF SEISMIC RESPONSE OF STEEL CYLINDRICAL LNG STORAGE TANKS

Numerical analysis of the seismic response of steel cylindrical LNG (liquified natural gas) storage tanks is essential to designing such structures to ensure their safety and structural integrity during earthquake events. The seismic analysis involves the assessment of the tank's response to ground motion and evaluating its structural performance under seismic loads. The LNG storage tanks' seismic behavior is rarely reported when the tank is subjected to strong earthquakes. This paper evaluates the vibration characteristic (modal analysis) and the seismic response analysis, e.g., time history response, displacement vs. time, and distribution of the maximum Von-Mises stresses of the perfect cylindrical storage tanks. This paper uses the finite element analysis (FEA) technique using ABAQUS CAE-2019 to evaluate the seismic capacity in peak ground acceleration (PGA). Three perfect cylindrical tanks (PCT) have been considered first for modal analysis, with two having high-yielding strength and the rest with low-yielding strength. Then El-Centro 1940 seismic waves are applied as a horizontal ground motion at the fixed base of the tanks. Finally, the results from the modal analysis regarding the first natural frequency of the tank models are compared with those obtained from experiments. The result’s comparisons illustrate that the numerical simulation agrees well with the experimental test results.

The effect of conical shell and converging/diverging tube on the charging performance of shell and tube latent heat thermal energy storage system

Latent heat storage is a promising method to overcome the problem of the intermittent nature of renewable sources. However, the main challenge in utilizing phase change materials is their poor thermal conductivity which leads to the slow charging and discharging of latent heat thermal energy storage tanks. Geometric optimization is a passive method to enhance the charging and discharging rate. In this paper, the geometric optimization of a shell and tube storage tank is studied numerically. Different configurations, including conical shell and tube, cylindrical shell and diffuser, cylindrical shell and nozzle, and a combination of conical shell and diffuser with different tilting angles is investigated. The height of all cases is assumed to be a constant number. The melting process is modeled by the enthalpy-porosity method, and the Boussinesq approximation is employed to consider the effect of natural convection. The governing equations are solved by a spatially and temporally second-order finite volume method. It is found that the main determining parameter is the cross-sectional area ratio of the phase change material at the top to its value at the bottom of the tank. By increasing this ratio, the effect of conductive heat transfer is attenuated, but natural convection is augmented. Since the charging rate is affected by these two heat transfer mechanisms, an optimum value of around 10 is obtained for this shape factor which results in an increased storage rate of 25 % compared to the case of cylindrical shell and tube storage tank. The optimum shape factor can be obtained either by a conical shell and tube or by combining a conical shell and a diffuser.

Spatial Trajectory Tracking of Wall-Climbing Robot on Cylindrical Tank Surface Using Backstepping Sliding-Mode Control

Wall-climbing robots have been well-developed for storage tank inspection. This work presents a backstepping sliding-mode control (BSMC) strategy for the spatial trajectory tracking control of a wall-climbing robot, which is specially designed to inspect inside and outside of cylindrical storage tanks. The inspection robot is designed with four magnetic wheels, which are driven by two DC motors. In order to achieve an accurate spatial position of the robot, a multisensor-data-fusion positioning method is developed. The new control method is proposed with kinematics based on a cylindrical coordinate system as the robot is moving on a cylindrical surface. The main purpose is to promote a smooth and stable tracking performance during inspection tasks, under the consideration of the robot's kinematic constraints and the magnetic restrictions of the adhesion system. The simulation results indicate that the proposed sliding mode controller can quickly correct the errors and global asymptotic stability is achieved. The prototype experimental results further validate the advancement of the proposed method; the wall-climbing robot can track both longitudinal and horizontal spatial trajectories stably with high precision.

Experimental Investigation on the Effect of Seal Presence on the Behavior of Double-Deck Floating Roofs in Cylindrical Steel Storage Tanks

Liquid storage, particularly oil and petrochemical products which are considered hazardous liquid, are an important part of the oil industry. Thin-walled vertical cylindrical steel storage tanks are widely used in recent years. Due to high sensitivity of these structures in an earthquake and other external excitations may lead to catastrophic consequences. For instance, huge economic losses, environmental damages, and casualities, many studies have been done about these structures. past studies showed that liquid storage tanks, equipped with a floating roof, are potentially vulnerable while subjected to seismic loads and earthquake has been considered as one of the most destructive natural hazards. The reason is that such tanks are made of two separated parts (shell and roof) which each may have its own responses; sometimes causing resonance phenomenon and so that, roof movements, roof-fluid interaction, roof-shell interaction, and also the way they are attached should still be investigated. Experimental tests of floating roof’s vertical fluctuation was performed in a full-scale reservoir tank and assessing of the results demonstrated that presence of a seal between floating roof and shell plate can significantly increase damping ratio in liquid sloshing and also suppress the roof`s vertical displacements. In other words, seal can control a floating roof and make it stop moving vertically over few cycles.

Minimum safety liquid levels for cylindrical storage tanks to prevent buckling under fluctuating wind loads

Among the diverse Natech scenarios, buckling of storage tanks under extreme winds is of particular concern due to the economical, ecological, and societal consequences the leakage of valuable, flammable, and hazardous substances in the tanks can bring about. Filling storage tanks with water has a stabilizing effect against buckling and has been adopted in practice to preserve the integrity of tanks under extreme wind loads. In previous studies, the description of wind load is mostly limited to rule-of-thumb formulas with empirical parameters, which is insufficient to make credible quantitative decisions in the prevention and preparedness phase of emergency management. In the present study, sophisticated numerical simulations of multiple correlated time histories of fluctuating wind loads and nonlinear finite element analysis allow for a technologically sound methodology for the evaluation of minimum safety liquid levels for storage tanks to prevent buckling under extreme winds. In the case studies, both the proposed methodology and the relevant Eurocode have been applied to assess the minimum safety liquid levels in more than one hundred scenarios of severe winds. It is observed that both approaches agreed that 94 scenarios were safe and 19 were unsafe. However, the remaining 13 scenarios were considered safe by the Eurocode-static-analysis approach while considered unsafe by the proposed approach indicating that the peak velocity pressure formula in Eurocode and static wind buckling analysis adopted in numerous previous studies systematically underestimate the role of fluctuating wind. The proposed methodology may be applied to help make quantitative decisions corresponding to wind disasters.