scholarly journals Numerical Simulation of Leakage and Diffusion Process of LNG Storage Tanks

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6282
Author(s):  
Xue Li ◽  
Ning Zhou ◽  
Bing Chen ◽  
Qian Zhang ◽  
Vamegh Rasouli ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Storage Tank ◽  
Methane Concentration ◽  
Leaf Shape ◽  
Liquid Pool ◽  
Storage Tanks ◽  
Vapor Cloud ◽  
Heavy Gas ◽  
Gas Cloud ◽  
And Diffusion

To investigate the evolution process of LNG (Liquefied Natural Gas) liquid pool and gas cloud diffusion, the Realizable k-ε model and Eluerian model were used to numerically simulate the liquid phase leakage and diffusion process of LNG storage tanks. The experimental results showed that some LNG flashed and vaporized rapidly to form a combustible cloud during the continuous leakage. The diffusion of the explosive cloud was divided into heavy gas accumulation, entrainment heat transfer, and light gas drift. The vapor cloud gradually separated into two parts from the whole “fan leaf shape”. One part was a heavy gas cloud; the other part was a light gas cloud that spread with the wind in the downwind direction. The change of leakage aperture had a greater impact on the whole spill and dispersion process of the storage tank. The increasing leakage aperture would lead to 10.3 times increase in liquid pool area, 78.5% increase in downwind dispersion of methane concentration at 0.5 LFL, 22.6% increase in crosswind dispersion of methane concentration at 0.5 LFL, and 249% increase in flammable vapor cloud volume. Within the variation range of the leakage aperture, the trend of the gas cloud diffusion remained consistent, but the time for the liquid pool to keep stable and the gas cloud to enter the next diffusion stage was delayed. The low-pressure cavity area within 200 m of the leeward surface of the storage tank would accumulate heavy gas for a long time, forming a local high concentration area, which should be an area of focus for alert prediction.

scholarly journals Numerical Simulation of Leakage and DiffusionProcess of LNG Storage Tanks

2021 ◽  
Author(s):  
Xue Li ◽  
Bing Chen ◽  
Vamegh Rasouli ◽  
Ning Zhou ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Phase Change ◽  
Storage Tank ◽  
Methane Concentration ◽  
Gas Diffusion ◽  
Liquid Pool ◽  
High Concentration ◽  
Vapor Cloud ◽  
Long Time ◽  
Heavy Gas ◽  
Gas Cloud

Abstract Background The previous researches mainly focused on the potential hazards associated with LNG leaks and the level of the influence of external environmental factors on the dispersion effect of LNG spills. Few considerations were given to phase change. Therefore, in order to investigate the evolution process of LNG liquid pool and gas cloud diffusion, the effect of phase change on dispersion during LNG release is studied to analyze the behavior characteristics of LNG liquid pool expansion and gas cloud diffusion, and the effect of the leaking aperture on the gas cloud diffusion process is also studied. Methods The Eluerian model and Realizable k-ε model were used to numerically simulate the liquid phase leakage and diffusion process of LNG storage tanks. The homogeneous Eulerian multiphase model was adopted to model the phase change process after LNG leaks to the ground. The Eulerian model defines that different phases are treated as interpenetrating continuum, and each phase has its own conservation equation. The average diameter of LNG droplet and NG bubble were set to 0.01 m. The standard k-ε model and realizable k-ε model are commonly used to describe turbulent motion. However, the realizable k-ε model can not only effectively solve the problem of curved wall flow, but also simulate free flow containing jets and mixed flows. In addition, the realizable k-ε model had higher accuracy in concentration distribution by simulating Thorney’s heavy gas diffusion field test. Therefore, the realizable k-ε model was selected for gas diffusion turbulence. Results The diffusion of the explosive cloud was divided into heavy gas accumulation, entrainment heat transfer and light gas drift. The vapor cloud gradually separated into two parts from the whole "fan leaf shape". One part was a heavy gas cloud, the other part was a light gas cloud which spread with the wind in the downwind direction. The change of leakage aperture had a greater impact on the whole spill and dispersion process of the storage tank. The increasing leakage aperture would lead to 10.3 times increase in liquid pool area, 78.5% increase in downwind dispersion of methane concentration at 0.5LFL, 22.6% increase in crosswind dispersion of methane concentration at 0.5LFL and 249% increase in flammable vapor cloud volume. Within the variation range of the leakage aperture, the trend of the gas cloud diffusion remains consistent, but the time for the liquid pool to keep stable and the gas cloud to enter the next diffusion stage was delayed. The low-pressure cavity area within 200 m of the leeward surface of the storage tank will accumulate heavy gas for a long time, forming a local high concentration area. Conclusion Within the variation range of leakage aperture, there will always be a local high concentration area within 200 m downstream of the storage tank. In the field near the storage tank, the clouds settle and accumulate towards the ground in the state of gas-liquid two-phase flow, and the density of the cloud is gradually lower than the air in the far field, manifesting as light gas diffusion. The methane concentration in this area is high and lasts for a long time, so it should be the focus area of alarm prediction.

scholarly journals Massive Fire Incidents of Multiple Aboveground Storage Tanks due to Vapor Cloud Explosion

2019 ◽  
Vol 2 (2) ◽  
pp. 102-108
Author(s):  
Shoichi Yoshida
Keyword(s):  
Storage Tank ◽  
Storage Facility ◽  
Storage Tanks ◽  
The Past ◽  
Oil Storage ◽  
The World ◽  
Vapor Cloud

The vapor cloud explosion (VCE) begins with a release of a large quantity of flammable vaporing liquid from a storage tank, transportation vessel or pipeline. If VCE occurs in an oil storage facility, multiple tanks burn simultaneously. There is no effective firefighting method for multiple tanks fire. It will be extinguished when oil burned out spending several days. Many incidents of multiple tanks fire due to VCE have occurred all over the world in recent 50 years. This paper reviews the past 6 incidents of multiple tanks fire due to VCE.

Collaborative Filtering Model Fusing Singularity and Diffusion Process

2014 ◽  
Vol 24 (8) ◽  
pp. 1868-1884 ◽  
Author(s):  
Xing-Yao YANG ◽  
Jiong YU ◽  
IBRAHIM Turgun ◽  
Bin LIAO ◽  
Yu-Rong QIAN
Keyword(s):  
Diffusion Process ◽  
Collaborative Filtering ◽  
And Diffusion

scholarly journals The effect of household storage tanks/vessels and user practices on the quality of water: a systematic review of literature

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Musa Manga ◽  
Timothy G. Ngobi ◽  
Lawrence Okeny ◽  
Pamela Acheng ◽  
Hidaya Namakula ◽  
...  
Keyword(s):  
Systematic Review ◽  
Water Quality ◽  
Storage Tank ◽  
Grey Literature ◽  
Water Storage ◽  
Storage Tanks ◽  
Water Storage Tank ◽  
Hygiene Practices ◽  
Quality Of Water ◽  
Vessel Material

Abstract Background Household water storage remains a necessity in many communities worldwide, especially in the developing countries. Water storage often using tanks/vessels is envisaged to be a source of water contamination, along with related user practices. Several studies have investigated this phenomenon, albeit in isolation. This study aimed at developing a systematic review, focusing on the impacts of water storage tank/vessel features and user practices on water quality. Methods Database searches for relevant peer-reviewed papers and grey literature were done. A systematic criterion was set for the selection of publications and after scrutinizing 1106 records, 24 were selected. These were further subjected to a quality appraisal, and data was extracted from them to complete the review. Results and discussion Microbiological and physicochemical parameters were the basis for measuring water quality in storage tanks or vessels. Water storage tank/vessel material and retention time had the highest effect on stored water quality along with age, colour, design, and location. Water storage tank/vessel cleaning and hygiene practices like tank/vessel covering were the user practices most investigated by researchers in the literature reviewed and they were seen to have an impact on stored water quality. Conclusions There is evidence in the literature that storage tanks/vessels, and user practices affect water quality. Little is known about the optimal tank/vessel cleaning frequency to ensure safe drinking water quality. More research is required to conclusively determine the best matrix of tank/vessel features and user practices to ensure good water quality.

scholarly journals Optimal Sizing of Rooftop Rainwater Harvesting Tanks for Sustainable Domestic Water Use in the West Bank, Palestine

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 573
Author(s):  
Sameer Shadeed ◽  
Sandy Alawna
Keyword(s):  
Storage Tank ◽  
Rainwater Harvesting ◽  
West Bank ◽  
Family Members ◽  
Optimal Size ◽  
Storage Tanks ◽  
Domestic Water ◽  
The West ◽  
Average Family ◽  
Rooftop Rainwater Harvesting

In highly water-poor areas, rooftop rainwater harvesting (RRWH) can be used for a self-sustaining and self-reliant domestic water supply. The designing of an optimal RRWH storage tank is a key parameter to implement a reliable RRWH system. In this study, the optimal size of RRWH storage tanks in the different West Bank governorates was estimated based on monthly (all governorates) and daily (i.e., Nablus) inflow (RRWH) and outflow (domestic water demand, DWD) data. In the estimation of RRWH, five rooftop areas varying between 100 m2 and 300 m2 were selected. Moreover, the reliability of the adopting RRWH system in the different West Bank governorates was tested. Two-time series scenarios were assumed: Scenario 1, S1 (12 months, annual) and scenario 2, S2 (8 months, rainy). As a result, reliable curves for preliminary estimation of optimal RRWH storage tanks for the different West Bank governorates were obtained. Results show that the required storage tank for S1 (annual) is more than that of the S2 (rainy) one. The required storage tank to fulfill DWD is based on the average rooftop area of 150 m2, the average family members of 4.8, and the average DWD of 90 L per capita per day (L/c/d) varies between (75 m3 to 136 m3) and (24 m3 to 84 m3) for S2 for the different West Bank governorates. Further, it is found that the optimal RRWH tank size for the 150 m2 rooftop ranges between 20 m3 (in Jericho) to 75 m3 (in Salfit and Nablus) and between 20 m3 (in Jericho) to 51 m3 (in Jerusalem) for S1 and S2 scenarios, respectively. Finally, results show that the implementation of an RRWH system for a rooftop area of 150 m2 and family members of 4.8 is reliable for all of the West Bank governorates except Jericho. Whereas, the reliability doesn’t exceed 19% for the two scenarios. However, the reduction of DWDv is highly affecting the reliability of adopting RRWH systems in Jericho (the least rainfall governorate). For instance, a family DWDv of 3.2 m3/month (25% of the average family DWDv in the West Bank) will increase the reliability at a rooftop area of 150 m2 to 51% and 76% for S1 and S2, respectively.

Floating Roof Influence on Seismic Response of Large Vertical Storage Tank

2013 ◽  
Vol 671-674 ◽  
pp. 1399-1402
Author(s):  
Ying Sun ◽  
Jian Gang Sun ◽  
Li Fu Cui
Keyword(s):  
Seismic Response ◽  
Storage Tank ◽  
Numerical Solutions ◽  
Fluid Pressure ◽  
Seismic Intensity ◽  
Site Conditions ◽  
Storage Tanks ◽  
Analysis Model ◽  
Base Shear ◽  
The Impact

To study the impact of floating roof on seismic response of vertical storage tank structure system subjected to seismic excitation, select 150000m3 storage tanks as research object, and the finite element analysis model of storage tanks with and without floating roof were established respectively. The seismic response of these two types of structure in different site conditions and seismic intensity were calculated and the numerical solutions were compared. The results show that floating roof has little impact on base shear and base moment in different site conditions and seismic intensity. Floating roof can effectively reduce the sloshing wave height. The influence of floating roof on dynamic fluid pressure decreases with the increase of seismic intensity, which is less affected by ground conditions.

Molecular dynamics simulation for structural heterogeneity and diffusion process in liquid GeO2

2021 ◽  
Vol 66 (1) ◽  
pp. 42-48
Author(s):  
Kien Pham Huu ◽  
Linh Nguyen Hong ◽  
Hien Pham Xuan ◽  
Linh Nguyen Thi Thuy ◽  
Quang Phan Dinh ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Length Distribution ◽  
Structural Heterogeneity ◽  
Dynamics Simulation ◽  
Angle Distribution ◽  
Structural Units ◽  
Oxide Systems ◽  
Dynamical Heterogeneity ◽  
Liquid Oxide ◽  
And Diffusion

In this paper, we perform a simulation about liquid GeO2. The structure and diffusion process are analyzed through the radial distribution function, the distribution of GeOx (x = 4, 5, 6) structural units, length distribution, angle distribution, and data visualization. Simulation results show that the structure of liquid GeO2 composes clusters of GeO4, GeO5, or GeO6. These clusters have sizes depending on pressure and are distributed heterogeneously in space. This result confirms the origin of dynamical heterogeneity in the liquid oxide systems. In addition, the diffusion coefficient of Ge and O decreases upon pressure. We show that the diffusion relates to the breaking bond Ge-O.

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