Large Storage Tanks Research Articles

A Study on the Sloshing Problem of Vertical Storage Tanks under the Action of Near‐Fault Earthquakes

In this study, through a vibration table test, finite element simulation, and research on the rationality of the wave‐height fortification of national storage tank specifications, the sloshing response of vertical storage tanks under the action of near‐fault ground motion was analyzed. The test results showed that the sloshing wave height of a vertical storage tank was larger under near‐fault or long‐period ground motions, and the relationship between the sloshing wave height and the peak acceleration of input ground motions was approximately linear. The numerical simulations of the model tank showed that the simulation wave height and the test wave‐height data were well fitted. Therefore, it was feasible to simulate the sloshing of large vertical storage tanks using ADINA software. In addition, a large number of sloshing simulations of near‐fault ground motions on 10,000 m3 vertical storage tanks were performed. The simulated wave height had a high correlation with the predominant period or pulse period of near‐fault ground motions. Under the calculation with similar parameters, the wave height of the tank standard in several countries had a lower fortification of the near‐fault excitation wave height. Through the root mean‐square method using a small sample size, a wave‐height correction under a near‐fault effect was applied to the wave‐height formula for the Chinese tank seismic specification. Finally, the problem of a double‐damping correction was addressed by adjusting China’s GB50341 wave‐height formula. This work provides a reference value for practical engineering applications.

Maintenance effects on life cycle of large above storage tanks

Maintenance effects on life cycle of large above storage tanks

Numerical analysis of geometrical and process parameters influence on temperature stratification in a large volumetric heat storage tank

This paper presents various numerical analyses of two-dimensional temperature and velocity fields in vertical cylindrical large volumetric heat storage tanks used in municipal heating applications. Numerical simulations were performed in order to investigate the shape impact of the heat storage tank (height-to-diameter ratio), the diffuser distance from the top of the tank, temperature difference between the warm and cold water and the volume flow variation on temperature stratification in the tank. The accuracy and precision of the numerical model was verified by comparing the numerical calculation results with the measurement results from the literature. An empirical model for the calculation of the tank wall (mantle) insulation thickness with maximum constant temperature inside the tank was also developed. The effect of reducing the insulation thickness and changing the seasons on quality of the temperature stratification and thermal losses through the tank insulation were analyzed. The financial analysis justified the possible reduction of the insulation thickness, and more flexible investment in the plant is presented.

Autonomous Positioning and Marking of Flaw Detection Wall-climbing Robot Based on Large Spherical Oil Storage Tanks

The emergence of wall-climbing robots alleviates the limitations of traditional manual flaw detection, and the autonomous positioning and marking system is its core research problem. By installing a three-axis accelerometer and a three-axis gyroscope on the wall-climbing robot, this paper firstly establishes a 3D model of the oil storage tank and stores its data in a database, then realizes the autonomous positioning of the wall-climbing robot on the oil storage tank, and finally marks the unqualified weld seam points.

Numerical analysis in a full-scale thermal energy storage tank with dual PCM capsules

Sensible thermal energy storage has been widely used with a single water storage tank for both heat-mode and cooling-mode. However, a large water storage tank is required to avoid the inevitable limitation of low energy storage density. Although latent heat thermal energy storage has compatibly high energy storage density, it requires separate tanks for heating-mode and for cooling-mode. This study considered a single tank for both heating and cooling modes, composed of 1620 (9 × 9 × 20) capsules filled with cooling-PCM or heating-PCM. Recently our research group developed a new effective thermal conductivity model that properly reflected the increased strength of natural convection in the molten PCM, and in this study we applied the model to simulate the full scale tank. Five different mixing ratios of cooling-PCM and heating-PCM, defined as the capsule number filled with cooling-PCM or heating-PCM to the total capsules in the tank, were investigated, and the range of the ratio of cooling-PCM and heating-PCM was found to satisfy both the required energy storage densities in heating and cooling demand. For the required energy storage densities of heating mode, 25 kwh/m3, and cooling mode, 30 kwh/m3, the results suggest the combined ratio in the dual PCM tank is within a 50/50–90/10 mixing zone ratio, of the cooling-PCM/heating-PCM respectively.

ASSESSMENT AND REMEDIATION OF A LIGHT NON-AQUEOUS PHASE LIQUID HYDROCARBON PLUME IN FRACTURED BEDROCK

INTRODUCTION During the extension of an access road on the Canadian Forces Base (CFB) Esquimalt in Colwood, British Columbia, a black, viscous, liquid hydrocarbon product was observed oozing from newly exposed bedrock fractures in the roadside. Road excavation was subsequently halted to undertake assessment and remediation of the hydrocarbon product. The exposed bedrock was dammed with sawdust, a geomembrane barrier was installed and the area was backfilled until an appropriate course of action could be determined. The site location is shown in Figure 1. The property boundary and key site features are shown in Figure 2; the hydrocarbon seep is shown in Figure 3. Bunker C oil is a heavy-end (high molecular weight) hydrocarbon product that has a specific gravity slightly less than water and is therefore a light non-aqueous phase liquid (LNAPL). The source of the LNAPL was inferred to originate from a decommissioned fuel depot located approximately 100 m distance uphill from the road, where 40,000 barrels of Bunker C fuel oil were historically stored in one of three, large above-ground storage tanks (ASTs). A Bunker C oil spill reportedly took place at the tank farm more than two decades prior; however, the spill volume was unknown and initial investigations found no evidence of contamination between the roadside LNAPL occurrence and the former AST. Furthermore, there was also anecdotal evidence that an historic asphalt manufacturing facility may have operated in the vicinity of the access road. A hydrocarbon product similar to Bunker C is used in the manufacture of asphalt. The source and extent of the LNAPL and the potential migration pathways to the roadside location were therefore unknown. When an LNAPL spill occurs in the subsurface, the LNAPL can migrate downward under gravity through the soil pore space in the unsaturated zone. When LNAPL encounters the ground water table (the top of the saturated zone), it tends to spread out laterally because it is less dense than water and will migrate primarily in the direction of the water table gradient (water table slope). However, when LNAPL encounters bedrock, the direction of LNAPL migration can become much more complicated depending on the degree and orientation of bedrock fractures that control its movement. When fracture density is sufficiently high and the fractures are interconnected, contamination is able to migrate down-gradient through the bedrock in the same manner as through unconsolidated materials. However, when dominant structural features are prevalent that favour specific orientations, preferential pathways are created that can result in the cross-gradient migration of LNAPL. This paper presents a case study for the assessment and remediation of LNAPL in bedrock at the Canadian Forces Base (CFB) Esquimalt (the site). Geological mapping of bedrock structural features has long been used by the mining industry to identify key structures associated with economic zones of mineralization and to predict the location and extent of mineralized targets. In a similar regard, to effectively remediate LNAPL within fractured bedrock requires the identification and characterization of any structural features that might be controlling the preferential migration of LNAPL within the subsurface to other areas of the site. A significant amount of surface outcrop is present at the site and this was recognized as a cost-effective opportunity to complete a geological assessment of the bedrock. A geological mapping program was subsequently undertaken to assess bedrock outcrops for fracture density, fracture aperture, the orientation of primary fracture sets and lithologic contacts. The area was also inspected for larger scale structural features such as faults, deformation and erosional features that might influence contaminant migration. Fracture sets and lithologic contacts were mapped by outcrop location, and fractures with visible LNAPL were mapped separately from those without LNAPL. The geological data collected was used to construct stereographic projections of structural planes on a stereonet. Poles to structural planes were plotted and colour-coded by area and by presence/absence of LNAPL. The plots were then analyzed individually, and as a composite plot, to identify the dominant preferential pathways controlling LNAPL migration at the site. By superimposing these features on areas where LNAPL was observed, LNAPL delineation targets were effectively identified and the plume was subsequently delineated with confidence and remediated.

Corrosion analysis and remaining useful life prediction for storage tank bottom

Corrosion of large storage tank bottom has been identified as the main threat to tank security around the world. Corrosion detection becomes the main approach to ensure the safety of large storage tanks. In this article, we propose a two-stage tank bottom corrosion analysis and remaining useful life prediction framework. In the first stage, the causes and mechanisms of tank bottom corrosion are analyzed, the evaluation metric system is established, and the fuzzy comprehensive evaluation method is used to evaluate the health status of tank bottom. The preliminary evaluation result in the first stage determines whether a subsequent remaining useful life prediction is required. If the tank bottom is not in healthy state, in the second stage, the remaining useful life prediction of the tank bottom is implemented by acoustic emission and risk-based inspection. Both qualitative and quantitative evaluation are carried out to provide a basis for the operation and maintenance decision of storage tanks.

7%Ni-TMCP鋼の特性と大型LNGタンクへの適用性

7%Ni-TMCP鋼の特性と大型LNGタンクへの適用性

Analytical solutions for the isobaric evaporation of pure cryogens in storage tanks

New analytical solutions have been derived for the isobaric evaporation of a pure liquid cryogen. In particular, expressions have been provided for the liquid volume, evaporation rate, Boil-off-Gas (BOG) rate, vapour temperature and vapour to liquid heat transfer rate as a function of time. Both equilibrium and non-equilibrium scenarios have been considered. In the former, the vapour and liquid cryogen are assumed to be in thermal equilibrium, while in the latter the vapour is treated as superheated with respect to the liquid and acts as an additional heat source.The derived solutions for two scenarios were validated against the numerical results for the evaporation of liquid methane and of liquid nitrogen in small, medium sized and large storage tanks that are used in industry. For the equilibrium model, the analytical solutions are exact. For the non-equilibrium model, the analytical solutions are valid for the whole duration of evaporation, except for a short transient period at the beginning of the evaporation. For physical quantities of industrial interest, they provide accurate estimates of liquid volume, BOG rate and BOG temperature, with the maximum deviations not exceeding 1%, 2% and 4.5%, respectively. The vapour to liquid heat transfer rate is also well predicted to within a maximum deviation of 5%.

Numerical Simulation of Large Crude Oil Storage Tank Fire under Various Wind Speeds

In order to analyse the influence of the wind speed on the fire characteristics and hazards of large crude oil storage tanks, this paper used the fire dynamics simulation software FDS to simulate the fire of a large crude oil storage tank under various wind speeds. The fire characteristics such as flame, smoke and temperature distributions of the tank under different wind speeds were studied. The thermal effects on the adjacent tank and the way that the firefighters cool the hazardous area were discussed. The results show that with the increase of the wind speed, the flame, smoke and temperature distributions shift and spread downwind. When tank fire occurs, the firefighters should set up movable firefighting water gun near the dangerous area and lay fire water hose to the burning tank and its neighbours, which provides a good preparation for the subsequent firefighting operation near the burning tank.

The Causes of Floods and Control Measures during the Rainstorm Period in Cities with Flat Terrain

In the process of rapid urban expansion, flooding has become a common problem in cities with flat terrain. This is due to the high volume and intensity of rainstorms, which has exceeded the drainage capacity of the existing municipal rainwater channels. Proposal has been made to divide large-area drainage into small-area drainage, disperse the discharge and add a self-controlled drainage pump to solve the problem of internal defects of the old city. At the same time, the new urban area will establish different rainstorm return periods according to the level of the road, build large underground storage tanks and rainwater pumping stations, and combine the newly proposed sponge city construction theory and deep water storage technology to retain and use part of the rainwater. At the same time, the siltation of dredged rivers and lakes will be increased and regional flood scientific dispatch during heavy rains will be implemented to improve the city's ability to resist heavy rains.

Coupling effects of the fragment impact and adjacent pool-fire on the thermal buckling of a fixed-roof tank

Abstract The combined loadings of the fragment impact and pool-fire caused by domino accidents in storage tank farms or oil depots can result in damage greater than that caused by a separate loading. However, due to the complexity of the combined loadings, these have not been well understood. In this study, the coupling effects of the fragment impact and adjacent pool-fire on the thermal buckling of a fixed-roof tank were numerically investigated. The effects of impact velocities, impact angles and fragment shapes on the failure mode and fire resistance of a fixed-roof tank were discussed. The results indicate that the coupling effects of the fragment impact and adjacent pool-fire were deeply different from those in which the fixed-roof tank was subjected to either fragment impact or adjacent pool-fire individually. The fire resistance and critical buckling temperature decreased for pre-damaged tanks comparing with no-pre-damaged tanks. Besides, the local buckling mode triggered by the adjacent pool-fire was depended on the impact dent zone caused by the fragment impact. Moreover, the fire resistance and critical buckling temperature reduced with the increase of the impact velocity, structural stability of the fragment and the decrease of the impact angle. This study can be used to understand the vulnerability and obtain the critical failure criterion of the large storage tanks under the coupling effects of multiple accidents, and optimize the steel structure design of oil tanks for resisting projectiles and pool-fires in tank farms to reduce the possibility of storage tank accidents.

Application of Static Sounding to Predict the Tilt of Large Oil Storage Tanks

The possibility of predicting the tilt of structures by special static-sounding data processing is examined. A criterion is proposed for the onset of tilting and non-uniform deformations of the foundation. The sequence in processing the results of static sounding in order to determine the direction and magnitude of the tilt of a structure is shown for a practical example.

Development of parametric fragility curves for storage tanks: A Natech approach

Natural hazards impose great distresses on many type of structures, which leads to large economic, environmental, and human losses. Large storage areas, in which large cylindrical storage tanks are used, are particularly vulnerable to certain natural events such as earthquakes, tsunami, and storms. This vulnerability can result in technological accidents (also known as Natech) such as the release of hazardous materials or the loss of valuable resources. The objective of this paper is to present a Natech-based approach for the development of fragility curves that can be used in the performance analysis and the design of storage tanks, for a large variety of tank configurations, and for various types of storage park/area setups. This is achieved through a parametric methodology that allows for specific tank modelling, instead of more traditional approaches (i.e., historical records). Furthermore, a formulation for the analysis of tank groups subjected to extreme events is presented. The model for isolated and grouped tanks, and its applications, are illustrated through several examples. This analysis is restricted to the case of ground supported, liquid-atmospheric storage tanks. Specifications for other tank geometries and operation conditions (e.g., elevated, rectangular or pressurized tanks) can be found elsewhere.

Stress analysis and strength assessment of ammonia water storage tank

In this paper, a large vertical cylindrical steel ammonia storage tank was numerical simulated. Strength and stability assessment under earthquake load, wind load, internal pressure and dead weight were performed. It is found the strength of the tank meets the strength requirements according to JB4732-1995 Steel Pressure Vessels-Design by Analysis. The tank is in stability even under the compressive stress at the leeward side of cylindrical vessel under the combined wind load and earthquake load.

A realistic vapour phase heat transfer model for the weathering of LNG stored in large tanks

Abstract A new non-equilibrium model relevant to LNG weathering in large storage tanks under constant pressure has been developed. It treats the heat influx from the surroundings into the vapour and liquid phases separately and allows for heat transfer between the two phases. The main heat transfer mechanisms in the vapour phase are assumed to be advection, due to upward flow of evaporated LNG, and conduction. It has been observed that the vapour temperature increases monotonically as a function of the height, in agreement with recent experimental results. In all the simulations performed the vapour to liquid heat transfer was small, also in line with recent experimental findings, and is estimated to contribute less than 0.3% to boil-off gas rates. The results of this work indicate that the heat transfer by the advective upward flow dominates the energy transfer within the vapour, while the natural convection, in the body of the vapour, can be neglected. The initial liquid filling has a pronounced effect on all the relevant variables, leading to a decrease in vapour temperature and boil-off gas temperature and an increase in boil-off rates. A rule of thumb for estimating the boil-off gas temperature in industrial storage tanks is provided.

In-situ non-contact 3D optical deformation measurement of large capacity composite tank based on close-range photogrammetry

Recently, fiber-reinforced composites are widely used in manufacturing of large storage tanks for transportation purposes, thanks to their excellent mechanical and chemical performance, and their good applicability to the shaping of particular geometries. In this contribution, a non-contact 3D optical deformation measurement technique is proposed for monitoring the deformation of carbon-fiber reinforced composite tank subjected to different loading scenarios, which could not be achieved by traditional displacement sensors and resistance strain gauges due to large measuring ranges. This technique is based on the close-range photogrammetry technology, wherein 3D information is extracted from two-dimensional photographs. This is done by positioning artificial reference point markers on the measuring tank before loading, and calculate the 3D coordinates of these markers through analyzing the group photos captured in each loading stage. By tracking and comparing the 3D coordinates of the point markers among different loading stages, the 3D deformation of the tank is obtained. The loading tests comprise both hydrostatic pressure and water-pressurizing tests. The performed in-situ measurements show that the proposed technique can fulfill the efficiency and accuracy requirement of deformation measurement in tank loading tests. This in turn significantly contributes to better understanding the mechanical response at the macroscopic scale, thus improving safety performance.

Behaviors of Thin‐Walled Cylindrical Shell Storage Tank under Blast Impacts

Large steel storage tanks designed with long‐span structures, employed for storing oil and fuel, have been widely used in many countries over the past twenty years. Most of these tanks are thin‐walled cylindrical shells. Owing to the high risk of gas explosions and the resulting deaths, injuries, and economic losses, more thorough damage analyses of these large structures should be conducted. This study examines the structural response of a simplified steel storage tank under a blast impact, as calculated by the LS‐DYNA software package. The numerical results are then compared with a scale‐model experiment. On that basis, the simplified storage tank prototype, which has a 15 × 104 m3 capacity, is analyzed using numerical simulation. In this study, we address issues around the variation in structural responses—particularly of the failure mode, resultant displacement, structural energy, and dynamic strain under the impact. In addition, we also discuss the effects of varying the internal liquid level, constraint conditions, and blast intensity.

ЗАБЕЗПЕЧЕННЯ НАДІЙНОЇ ЕКСПЛУАТАЦІЇ НАФТОВИХ РЕЗЕРВУАРІВ У СКЛАДНИХ ГЕОТЕХНІЧНИХ УМОВАХ ПРИ СЕЙСМІЧНИХ ВПЛИВАХ

ЗАБЕЗПЕЧЕННЯ НАДІЙНОЇ ЕКСПЛУАТАЦІЇ НАФТОВИХ РЕЗЕРВУАРІВ У СКЛАДНИХ ГЕОТЕХНІЧНИХ УМОВАХ ПРИ СЕЙСМІЧНИХ ВПЛИВАХ

Modal Analysis and Verification of Super Large FRP Combined Tank System Considering Reservoir Sloshing

The modal analysis and verification of super large FRP combined storage tank structure without floating roof are carried out. First, the finite element model of the structure system of the super large FRP composite storage tank without floating roof is established by ADINA. Then, the modal analysis of the structure system of the super large FRP composite storage tank without floating roof is carried out. Finally, the theoretical analysis of the sloshing frequency of the liquid storage is compared with the finite element results. The results show that the larger water storage height is, the larger the sloshing frequency is, on the contrary the larger the storage tank radius is, the smaller the sloshing frequency is. The theoretical analysis of the sloshing frequency of the super large FRP storage tank system is in good agreement with the results of the finite element calculation, and the correctness of the finite element model and the analysis method of the super large FRP composite storage tank structure system is verified. The calculation formula of the basic frequency of the storage sloshing of the super large FRP combined tank system is given.