Spherical Storage Tank Research Articles

Phase equilibrium calculations with specified vapor fraction

Phase equilibrium calculations have been extensively explored over the years, with numerous industrial applications, where pressure and temperature specifications are the most common. Different problems, however, may require different specifications for solving phase equilibrium. This article aims to develop a flash calculation with specified temperature or pressure and vapor fraction, termed ψβ-flash, which can be useful in studies of storage tanks and distillation columns. An algorithm is developed with an external loop for pressure or temperature optimization and an inner loop for the isobaric–isothermal-flash calculation. The method is efficient in predicting pressure for different binary and ternary mixtures, including refrigerants, hydrocarbons, and carbon dioxide, even in complex scenarios such as regions with retrograde condensation. The computational demand is investigated, revealing that calculations within the isobaric–isothermal-flash primarily contribute to the total computational cost, rather than pressure optimization. Finally, two case studies highlight the method’s efficiency: one involving a spherical storage tank, where we compute pressures based on liquid height to classify the safe operational region, and another focusing on a distillation tray, predicting temperatures driven by changes in liquid height to provide insights into separation performance.

Using fuzzy cognitive map in bow tie method for dynamic risk assessment of spherical storage tanks: A case study

The present study aimed to perform a dynamic risk assessment of liquefied petroleum gas (LPG) in spherical storage tanks using the Hazard and Operability (HAZOP) method. The “LPG release from spherical storage tank” scenario was determined to be a top event based on the risk level. The causes and consequences of this scenario were then specified using the Bow-Tie method. Additionally, fuzzy cognitive mapping (FCM) was utilized to identify the most critical threats, consequences, and effective barriers in a dynamic approach. Results showed that fracture/rupture in pipelines/a storage tank due to fire had the highest output degree and was identified as the most influential threat in the occurrence of the LPG release. Fatality/injury due to fire and explosion had the highest input degree and was more influenced by the release of LPG as the main consequence in the selected scenario. The findings of this study enabled us to make a logical decision about effective barriers for avoiding and minimizing the release of LPG and its threats and consequences based on the fuzzy cognitive map. Moreover, the results of this study showed that the FCM method could determine the most critical nodes with a higher degree and represent their relationships.

Natural convection effects in insulation layers of spherical cryogenic storage tanks

Natural convection effects in the insulation layers of spherical storage tanks are studied for different cryogenic fluids and tank sizes or curvatures. The non-vacuum-based insulation layers of these tanks are made of gas-filled porous materials such as perlite or glass bubbles. The large temperature difference that can exist between the inner cold wall and outer hot wall may create convective patterns with a multi-cellular flow within the insulation-filled annulus and lead to a higher boil-off rate and cryo-pumping effects. A main objective in the design of these systems is the elimination of the convective patterns by a proper choice of insulation properties. This work examines the impact of the insulation permeability or the Rayleigh number (Ra) on the type of convective flows for liquified natural gas (LNG) and liquid hydrogen (LH2) spherical storage tanks. Bifurcation diagrams of possible solutions are generated by numerical solutions of the governing equations at different Ra numbers. It is found that as Ra increases, new convective cells emerge near the south pole of the insulation layer due to unstable density stratification and lead to the distortion of isotherms, bringing the cold boundary towards the external hot boundary. When the temperature difference is large as in the case of LNG and LH2 tanks, there exist regions of multiple solutions in which multi-cell convective solutions may co-exist with a crescent-shaped weakly convective solution. In order to eliminate the possibility of multi-cell convection, inversion of the cold boundary, and reduce the boil-off rate, the Ra value of the insulation system should be below the limit point of the convective branch.

SIMULASI PENYEBARAN GAS BIOHIDROGEN DI DALAM LOJI BIOGAS MENGGUNAKAN PERKOMPUTERAN DINAMIK BENDALIR DAN PENILAIAN KESAN KEBAKARAN DAN LETUPAN

Accidental release of biohydrogen (bioH2) gas in biogas plant has a high risk to cause fire and explosion incidents. Thus, computational fluid dynamics (CFD) was used to study the dispersion of 158 kg of bioH2 gas through pipe leaks at a pure bioH2 spherical storage tank. The TNT-equivalent explosion model found that the threat zone which can destroy buildings due to overpressure exceeding 55 kPa was located at a radius of 9.31 m from the centre of the explosion at the fermenter. Further evaluation using the Dow’s fire and explosion index (F&EI) expects a maximum probable day outage (MPDO) and business interruption (BI) of 43 days and USD165,210, respectively. Therefore, safety control in terms of elimination of ignition sources, material replacement, engineering controls, safety components, layout design, administrative controls and personal protective equipment have been successfully proposed. In conclusion, this study has successfully simulated the dispersion of bioH2 gas and evaluated the impact of fire and explosion on biogas plant.

Steady Magnetohydrodynamic Micropolar Casson Fluid of Brownian Motion Over a Solid Sphere with Thermophoretic and Buoyancy Forces: Numerical Analysis

The impact of heat transfer in micropolar fluid may be developed due to its various promising applications in engineering, bio-medical sciences, geo-thermal progression, spherical storage tanks, nuclear power plants, automobile sectors etc. Motivated by such significance, the current study is to expound the influences of micropolar Casson fluid flow over a solid sphere with Brownian motion, thermophoretic force and buoyancy force surrounded by porous medium. The adopted model having complex PDE’s are reduced to dimensionless ODE’s by utilizing proper similarity solutions. A numerical approach have been carried out for velocity, micro rotation, temperature and concentration, the solutions are procured by Matlab Bvp4c code and plotted graphs for diverse involved parameters. An adequate result is acquired by an assessment with earlier available work. The effects of key parameters on surface drag coefficient, surface thermal flux and particles concentration flux are examined and displayed in tabular form. Grash of number raises the profiles of thermal flux and concentration flux where the buoyancy force is more dominant. Further, the obtained results indicate that the angular velocity is elevated near the surface of the sphere, and they behaves asymptotically far away from the surface due to the effect of micropolar parameter. Moreover, temperature and molar species concentration are enriched with upper values of micropolar factor. It is perceived that, augmented values of Casson parameter amplifies the velocity outline.

Reynolds number effects on the wind pressure distribution on spherical storage tanks

Spherical storage tanks are important industrial equipment with typical bluff body shape, the aerodynamic loads of which are significantly affected by the Reynolds number (Re). In the present research, wind tunnel tests are carried out on spherical storage tanks with 4–20 supporting columns and a range of surface roughness (ks/D ​= ​0, 0.002 and 0.004) under uniform and atmospheric boundary layer (ABL) flows with Re ranging from 105 to 106. The Reynolds number effects on the aerodynamic drag and uplift coefficients, mean and RMS wind pressure distributions are analyzed. The separation angle on the upper hemi-sphere shifts from 135° (super-critical) to 120° (trans-critical) at Re ​≈ ​6.5 ​× ​105 for a smooth tank in the uniform flow. The trans-critical self-modeling Re range criteria are determined by analyzing the similarity of mean and RMS wind pressure coefficient distribution patterns. It is indicated that in the ABL flow, when ks/D ​≥ ​0.002, the mean and RMS wind pressure distribution of a spherical tank in the trans-critical self-modeling Re range can be simulated with merely Re ​> ​2.0 ​× ​105, thus providing a guidance for wind tunnel simulation of sphere-like bodies. Moreover, a piecewise mean wind pressure coefficient model in the trans-critical self-modeling Re range for spherical storage tanks is established for engineering reference.

Safety assessment of natural gas storage tank using similarity aggregation method based fuzzy fault tree analysis (SAM-FFTA) approach

Fault tree analysis (FTA) is an important method to analyze the failure causes of engineering systems and evaluate their safety and reliability. In practical application, the probabilities of bottom events in FTA are usually estimated according to the opinions of experts or engineers because it is difficult to obtain sufficient probability data of bottom events in fault tree. However, in many cases, there are many experts with different opinions or different forms of opinions. How to reasonably aggregate expert opinions is a challenge for the engineering application of fault tree method. In this study, a fuzzy fault tree analysis approach based on similarity aggregation method (SAM-FFTA) has been proposed. This method combines SAM with fuzzy set theory and can handled comprehensively diverse forms of opinions of different experts to obtain the probabilities of bottom events in fault tree. Finally, for verifying the applicability and flexibility of the proposed method, a natural gas spherical storage tank with a volume of 10,000 m3 was analyzed, and the importance of each bottom event was determined. The results show that flame, lightning spark, electrostatic spark, impact spark, mechanical breakdown and deformation/breakage have the most significant influence on the explosion of the natural gas spherical storage tank.

Use of a Novel Resistive Strain Sensor Approach in an Experimental and Theoretical Study Concerning Large Spherical Storage Tank Structure Behavior During Its Operational Life and Pressure Tests.

This paper introduces a new method for the use of tensor-resistive sensors in large spherical storage tank equipment (over 12,000-mm diameters). We did an experiment with 19 petroleum or ammonia product sphere-shaped storage tanks with volumes of 1000 and 1800 cubic meters, respectively. The existing literature only contains experiments based on sensors for tanks with diameters no larger than 600 mm. Based on a number of resistive strain sensor measurements on large spherical pressurized vessels regarding structural integrity assessment, the present paper is focused on the comparison between "real-life" obtained sensor data versus finite element method (FEM) simulation results. The present paper is structured in three parts and examines innovative directions: the use of the classic tensor-resistive sensors in a new approach concerning large structural equipment; an original 3D modeling method with the help of the FEM; and conclusions with possible implications on the regulations, design, or maintenance as a result of the attempt of mutual validation of the new methods previously mentioned.

Evaluation of Thermal Stratification Inside a New Model of Spherical Water Storage Tank Using a Computational Fluid Dynamics 6 Degrees of Freedom Solver

Abstract In this work, a computational analysis of a spherical solar hot water storage tank during the discharging process is carried out by using the commercial code ansys-fluent.15. The study investigates a new type of spherical heat storage tank. A hinged baffle is fixed at the tank vertical axis to increase the discharge flow rate without a thermocline layer. The dynamic mesh LAYERING technique is used to update the computational domain during the movement of the hinged baffle. The passive pitching of the submerged baffle is due to the fluid-dynamic loads. This model limits the mixture between hot and cold water regardless of the inlet flow rate. A comparative study between tanks with typical diffusers and the hinged baffle model is considered. The comparison of the computational fluid dynamics results with available experimental data showed a good agreement. Examinations of the temperature contours indicate that for the typical models, the interaction between the incoming cold water and the stored hot water gives rise to a thick thermocline layer where its temperature and thickness are related to the intensity of the mixing process. The suggested model shows high stratification efficiency along the discharging process.

Static and Time History Earthquake Analysis of LPG Spherical Steel Tanks in Iraq

Spherical storage tanks are widely used in Iraq for store hazardous liquid petroleum gas LPG which, thus it must be adequately designed for seismic actions. This paper present static and time history analysis of LPG tanks in Iraq using UBC97 code. The time history analysis accomplished by using three artificial earthquakes generated using SIMQKE_GR program in additional to El Centro earthquake records scaled according to PGA. The investigations were performed on the tank in Maysan province which was selected to be representative the other tanks in Iraq due to recently seismic activity in Maysan. The study comprised finite element modeling using STAAD Pro program for the estimation of the dynamic and static responses of the tank structure. The study is performed for both conditions of empty tank and at operating with 100% fill of LPG. The description of the properties and allowable stresses LPG tank used in Iraq is presented. Its concluded that time history analysis govern the tank behavior. The dynamic magnification factor of 1.4 for displacements and stresses was obtained which reflect the importance of dynamic analysis. The stresses of columns and sphere are within allowable limits except at sphere/column connection which slightly exceed the allowable limit, while the stresses in diagonal bracings are exceed the yielding limit thus double angle section is inadequate

Improving the Performance of Storage Tank Fault Diagnosis by Removing Unwanted Components and Utilizing Wavelet-Based Features.

This paper proposes a reliable fault diagnosis model for a spherical storage tank. The proposed method first used a blind source separation (BSS) technique to de-noise the input signals so that the signals acquired from a spherical tank under two types of conditions (i.e., normal and crack conditions) were easily distinguishable. BSS split the signals into different sources that provided information about the noise and useful components of the signals. Therefore, an unimpaired signal could be restored from the useful components. From the de-noised signals, wavelet-based fault features, i.e., the relative energy (REWPN) and entropy (EWPN) of a wavelet packet node, were extracted. Finally, these features were used to train one-against-all multiclass support vector machines (OAA MCSVMs), which classified the instances of normal and faulty states of the tank. The efficiency of the proposed fault diagnosis model was examined by visualizing the de-noised signals obtained from the BSS method and its classification performance. The proposed fault diagnostic model was also compared to existing techniques. Experimental results showed that the proposed method outperformed conventional techniques, yielding average classification accuracies of 97.25% and 98.48% for the two datasets used in this study.

Leakage Detection of a Spherical Water Storage Tank in a Chemical Industry Using Acoustic Emissions

Spherical storage tanks are used in various industries to store substances like gasoline, oxygen, waste water, and liquefied petroleum gas (LPG). Cracks in the storage tanks are unaccepted defects, as storage tanks can leak or spill the contained substance through these cracks. Leakage from contained hazardous substances storage tanks can contaminate the environment and may lead to fatal accidents. Therefore, the ability to detect cracks from spherical storage tanks is necessary to avoid damage to the environment and to ensure public safety. In this paper, we present a crack detection case study of a spherical tank. The detection was performed using time-domain statistical features and a machine learning algorithm. The proposed method consists of (1) extraction of statistical features from the acoustic emissions (AE) acquired from the spherical tank, and (2) classification of the nonlinear data using a support vector machine (SVM). We evaluate the proposed algorithm with AE data obtained from the spherical tank, demonstrating that the algorithm effectively discriminates between normal and crack conditions. These results show that the proposed algorithm is effective for detecting cracks in spherical storage tanks.

Residual Stress Distribution Analysis in Advanced Materials by Neutron Diffraction: The Case of Spherical Storage Tank Butt Weld

The two-axis diffractometer SPN-100 at the Center of Accelerators and Nuclear Analytical Methods (CANAM) in Řež, is a neutron diffraction instrument dedicated to residual stress analyses in polycrystalline materials, it has recently been equipped with a new two-dimensional position sensitive detector (2D-PSD) and a six-axis robotic arm for sample positioning. Recent results of strain/stress distribution measurements with the upgraded tools are presented. The measured materials are made of C-Mn unalloyed steel used for spherical storage tank. Welding-induced residual stresses have direct influence on ductility and toughness of both weld metal and heat affected zone of the weld area, which affect the service life time of structures. Normal, transversal and longitudinal components of the stresses obtained in the vicinity of the butt weld from a spherical storage tank were measured by neutron diffraction at CANAM.

Seismic performance of spherical liquid storage tanks: a case study

Spherical storage tanks are widely used for various types of liquids, including hazardous contents, thus requiring suitable and careful design for seismic actions. On this topic, a significant case study is described in this paper, dealing with the dynamic analysis of a spherical storage tank containing butane. The analyses are based on a detailed finite element (FE) model; moreover, a simplified single-degree-of-freedom idealization is also set up and used for verification of the FE results. Particular attention is paid to the influence of sloshing effects and of the soil–structure interaction for which no special provisions are contained in technical codes for this reference case. Sloshing effects are investigated according to the current literature state of the art. An efficient methodology based on an “impulsive–convective” decomposition of the container-fluid motion is adopted for the calculation of the seismic force. With regard to the second point, considering that the tank is founded on piles, soil–structure interaction is taken into account by computing the dynamic impedances. Comparison between seismic action effects, obtained with and without consideration of sloshing and soil–structure interaction, shows a rather important influence of these parameters on the final results. Sloshing effects and soil–structure interaction can produce, for the case at hand, beneficial effects. For soil–structure interaction, this depends on the increase of the fundamental period and of the effective damping of the overall system, which leads to reduced design spectral values.

Sanacija zavarivanjem prslina sfernog rezervoara za etilen

Pressure vessel, spherical, of 3000 m3 working volume, where ethylene is placed, is made of microalloyed steel Nioval 47 - P460NL1 (EN 10028: 3), with wall thickness 18mm and welded on 12 supporting pillars. Regular tests were performed by non-destructive methods (visual, magnetic particle testing, ultrasonic testing) and the indications such as undercuts, group of pores, the lack of weld, craters formed during vessel manufacturing. What is very important but has not been paid enough attention to over the past fifteen years is the visual inspection of the base material of the spherical storage tank, where the indications such as cracks with a total length of over 6000 mm and a depth of 6 to 12 mm (examined by ultrasound) were observed, which were not observed during previous inspection. This paper presents the technological process of repairing of tank using 111 welding process, as well as testing of welded joints after repair. Tank is successfully repaired and tested. Results of this work indicate the need for more detailed testing of base metal in future.

Integrity assessment of ammonia spherical storage tank

The integrity of the ammonia spherical tank (with a volume of 1800 m3 and the outer diameter of 15120 mm, nominal wall thickness 30 mm) was analyzed due to discovered cracks on the longitudinal and transverse but joints of the segments, of different lengths and depth. The calculation according to EN 13445-3: 2014 specifies the minimum required spherical shell wall thickness. The finite element method was used to analyze the cracks and determine the hoop stress value. The stress intensity factor for the analysed cracks was analytically determined, and the obtained values were compared with the critical value of the stress intensity factor to assess the integrity of the observed structure.

Quasi-Omnidirectional Fuzzy Control of a Climbing Robot for Inspection Tasks

This work presents a novel method to quasi-omnidirectional control of an intelligent inspection robot designed to work inside and outside spherical storage tanks. The main objective is to promote a stable and smooth navigation during inspection tasks, ensuring the safety motion under adhesion and kinematic constraints. The robot is designed with four independent steerable magnetic wheels and a mechanical topology that allows the correct adjustment of adhesion system. A scheduled Fuzzy control is developed to achieve an optimal behavior and maximize the robot’s maneuverability, considering the magnetic restrictions of adhesion system and kinematic constraints of the inspection robot. The high adaptability of its mechanical topology (i.e., wheel misalignment, magnetic adhesion system, wheel camber and flexibilities in mechanical structure) and gravitational disturbance introduce many nonlinear characteristics in dynamic behavior that cannot be neglected, making the determination of its dynamic model a complex task. The Fuzzy approach allows to project a control system without a depth knowledge of its dynamic properties, to minimize the dynamic disturbances found in robot structure. Thus, the proposed motion control works according to the robot specific characteristics to ensure the quasi-omnidirectional motion over a reliable adhesion to tank surface and to minimize the effects of wheels kinematic constraints.

Construction cost estimation of spherical storage tanks: artificial neural networks and hybrid regression\u2014GA algorithms

One of the most important processes in the early stages of construction projects is to estimate the cost involved. This process involves a wide range of uncertainties, which make it a challenging task. Because of unknown issues, using the experience of the experts or looking for similar cases are the conventional methods to deal with cost estimation. The current study presents data-driven methods for cost estimation based on the application of artificial neural network (ANN) and regression models. The learning algorithms of the ANN are the Levenberg–Marquardt and the Bayesian regulated. Moreover, regression models are hybridized with a genetic algorithm to obtain better estimates of the coefficients. The methods are applied in a real case, where the input parameters of the models are assigned based on the key issues involved in a spherical tank construction. The results reveal that while a high correlation between the estimated cost and the real cost exists; both ANNs could perform better than the hybridized regression models. In addition, the ANN with the Levenberg–Marquardt learning algorithm (LMNN) obtains a better estimation than the ANN with the Bayesian-regulated learning algorithm (BRNN). The correlation between real data and estimated values is over 90%, while the mean square error is achieved around 0.4. The proposed LMNN model can be effective to reduce uncertainty and complexity in the early stages of the construction project.

Investigating thermal performance of an ice rink cooling system with an underground thermal storage tank

This study deals with mathematical modeling and energy analysis of an ice rink cooling system with an underground thermal energy storage tank. The cooling system consists of an ice rink, chiller unit, and spherical thermal energy storage tank. An analytical model is developed for finding thermal performance of the cooling system. The model is based on formulations for transient heat transfer problem outside the thermal energy storage tank, for the energy needs of chiller unit, and for the ice rink. The solution of the thermal energy storage tank problem is obtained using a similarity transformation and Duhamel superposition techniques. Analytical expressions for heat gain of the ice rink and energy consumption of the chiller unit are derived as a function of inside design air, ambient air, and thermal energy storage tank temperatures. An interactive computer program in Matlab based on the analytical model is prepared for finding hourly variation of water temperature in the thermal energy storage tank, coefficient of performance of the chiller, suitable storage tank volume depending on ice rink area, and timespan required to attain an annually periodic operating condition. Results indicate that operation time of span 6–7 years will be obtained periodically for the system during 10 years operating time.

Plate Diffuser Performance in Spherical Tank Thermocline Storage System

Thermal energy storage (TES) systems that store sensible heat in liquid media require the use of storage tanks. Spherical tanks require less building material and insulation, which might reduce the overall cost of a TES system while providing structural rigidity. The current study investigates an optimized plate diffuser in a thermocline spherical tank storage system to possibly increase the discharge flow rate without disrupting the thermocline region and without reducing the tank thermal efficiency. For low temperature (10–90 °C heat storage applications), such as heating, ventilation, and air conditioning (HVAC) and thermal water desalination, storing hot water in a thermocline system can increase the system thermal efficiency by up to 40% when compared to a fully mixed water tank and reduce the installation cost by 30% compared to a two-tank system. This study examines using a spherical tank in a thermocline system for such applications. A computational fluid dynamic (CFD) study simulated the discharge process from a spherical storage tank thermocline water system. Thermocline thickness and temperature profile in the tank were numerically determined for Reynolds number, Re = 600 and Froude number, Fr = 1.2; results were then experimentally validated. A CFD parametric study with (500 < Re < 7500) and (0.5 < Fr < 3.3): (i) determined the influence of tank flow dimensionless numbers (Reynolds, Froude, Richardson, and Archimedes) on thermal efficiency and thermocline thickness, (ii) produced an equation to predict the tank thermal efficiency using flow dimensionless numbers, and (iii) estimated the thermocline region volume occupation as a percentage of the total volume. The study of an optimized plate diffuser produced an equation for thermal efficiency based on Re and Fr numbers and estimated a thermocline volume equal to 15% of total tank volume. Flow rate ramp up by a factor of 3 was possible after the thermocline region was formed without losing tank thermal efficiency.