Tank Overflow Research Articles

Risk Analysis of Jet A-1 Tank Filling and Storage Processes at the Shorebase

Coastal Logistics Centers (CLS) provide logistics support to deep-sea drilling operations. Jet A-1 (helifuel), required for helicopters that transfer personnel to drilling ships, is filled into tanks from the tanker arriving at CLS and stored in open areas. Jet A-1 is a hazardous chemical with flammable and toxic effects and can also explode when exposed to flame. Risk analysis of this hazardous chemical is essential for CLS. This study aimed to determine the process hazards and risk analysis in the filling and storage operation of Jet A-1 from tankers to tanks. For this purpose, the Preliminary Hazard List (PHL) and Preliminary Hazard Analysis (PHA) were performed. Then, a Hazard and Operability (HAZOP) study was carried out based on these analysis results. The HAZOP study identified Jet A-1 overflow from the tank as a high-risk event. Afterward, Event Tree Analysis (ETA) was performed on the initial event of Jet A-1 spilling due to tank overflow. In ETA analysis, immediate ignition, delayed ignition, and explosion probabilities resulting from delayed ignition were calculated with the CCPS (Center for Chemical Process Safety) Module. The probability and frequency values of accident scenarios were calculated as P=0.0028, f=1.736 x10-4 year-1 for jet fire, P=0.0225, f=1.395x10-3 year-1 for vapor cloud explosion, P=0.127, f=7.874x10-3 year-1 for flash fire, P=0.847, f = 0.0525 year-1 for toxic release, respectively. It was determined that all accident scenario frequency values were above the legislation threshold value (10-4 year-1). Design solutions and preventive measures have been proposed to reduce risks. The combination of risk analysis methods is effective in risk assessment studies.

Fecal sludge characterization, treatment, and resource recovery options: a state-of-the-art review on fecal sludge management.

A rise in population and urbanization demanded that a robust fecal sludge management (FSM) value chain be used to restructure the sanitation system throughout the world securely. A significant global need exists to adopt efficient and sustainable FSM. On-site sanitation systems (OSS) produce fecal sludge (FS). FS is produced when excreta and blackwater are combined and stored or treated, either alone or in combination with greywater. FS can be semisolid or slurry and raw or partially digested. Critical examination of FS characteristics, i.e., biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), and pathogen count, varies from 600-56,836mg/l, 6656 to 201,200mg/l, 830-123,000mg/l, and 105 to 109 E. coli/l of FS respectively. Helminth eggs range from 2500-25,000/l of FS. Public health and the environment are negatively impacted by septic tank overflows and the careless discharge of FS into open spaces affecting groundwater quality, water bodies, irrigation fields, open drains, places outside villages, etc. Thus, deciding on a proper treatment technology for FS before discharging it into open land or reusing FS is essential to create a pollution-free environment. This paper highlights the practices adopted for FSM under its different processes, such as collecting, characterization, treating, and reusing of on-site FS and bibliometric analysis on documents on fecal sludge. A thorough analysis has been carried out by reviewing all important literature available globally.

Increasing performance efficiency of reconstructed oil fields

In the oil-gathering stations of most OGPDs, oil water sand clay mixtures that enter the settling equipment after passing through the separators are initially separated and collected in appropriate tanks. Prior to the production of commercial oil, more labor and energy is utilized to separate water and sand-clay mixtures from oil. Tanks are quickly contaminated with bottom sediments consisting of sand-clay and cleaning of them is difficult. Mixtures of sand-clay-water from settler, formation water from oil tanksa are drained into open oil traps, as a result, the environment is polluted with oil wastes and oil losses occur. It is more efficient to use a horizontal oil and gas separator to overcome shortcomings identified in the reconstruction of the tank farm with a capacity of more than 1.500 m3/day. Sand-clay separator should be installed at the inlet of it to protect the separator and tanks from sand-clay mixed sediments. Sand-clay separators should be installed inside the overflow tanks for better separation of formation water and sand-clay mixtures from oil, oil suspensions and sand-clay mixtures from water in formation water storage tanks. In order to reduce evaporation losses in the tanks, an auxiliary palte should be used under the PSV and the gas phase of the technological tanks and commercial oil tanks should be connected via pipes.

Evolutions of the LOPA method to a fully quantified method

AbstractLOPA (Layer Of Protection Analysis) is a risk analysis method developed to highlight various layers of protection from the process design to the emergency response. In its basic conception, each barrier is associated with a Risk Reduction Factor (RRF) corresponding to the inverse of the probability of failure (e.g., RRF = 10 corresponds to a probability of failure on demand [PFD] = 0.1). In its most common form, the LOPA method uses orders of magnitude for the probability of failure and frequency values generally inspired by those reported by the center for chemical process safety books. Frequency of accidents then consists of multiplying the frequency of the initiating event by the PFD allocated to each barrier. The LOPA method is an attractive approach because, at first sight, it is relatively easy to implement and can be used by engineers who are not necessarily specialists in industrial risk analysis. In reality, this approach can quickly lead to an erroneous estimate of accident frequency. This article presents how LOPA can be applied in a quantified way and the expected benefits. A practical application example related to tank overflow will highlight the advantages of using a fully quantified method.

A Novel Approach to Avoiding Technically Unfeasible Solutions in the Pump Scheduling Problem

Optimizing pump operation in water networks can effectively reduce the cost of energy. To this end, the literature provides many methodologies, generally based on an optimization problem, that provide the optimal operation of the pumps. However, a persistent shortcoming in the literature is the lack of further analysis to assess if the obtained solutions are feasible from the technical point of view. This paper first showed that some of these available methodologies identify solutions that are technically unfeasible because they induce tank overflow or continuous pump switching, and consequently, proposed a novel approach to avoiding such unfeasible solutions. This consisted in comparing the number of time-steps performed by the hydraulic simulator with the predicted value, calculated as the ratio between the simulation duration and the hydraulic time-step. Finally, we developed a new model which couples Epanet 2.0 with Pikaia Genetic Algorithm using the energy cost as an objective function. The proposed method, being easily exportable into existing methodologies to overcome the limitations thereof, thus represents a substantial contribution to the field of pump scheduling for optimal operation of water distribution networks. The new method, tested on two case studies in the literature, proved its reliability in both cases, returning technically feasible solutions.

Avoiding Buffer Tank Overflow in an Iron Ore Dewatering System with Integrated Control System

High water usage is necessary while ore passes through the many stages of a mineral processing plant. However, a dewatering system filters the final ore pulp product to remove the water, which is reutilized in the previous processes. This step is fundamental to reducing the fresh new water consumption. Usually, several tanks, pumps, and filters form a dewatering system—any failure or shutdowns from those components disbalance the pulp flow. The waste of many tons of water and ore products for a tailing dam is the worst consequence of a mass disbalance in a dewatering system. This paper proposes an advanced regulatory control strategy composed of cascade and override loops for a dewatering system. The main purpose is to increase the production period, even under filter failure and changes in the inlet pulp characteristics. This control strategy is evaluated using a digital model of a large-scale Brazilian iron ore processing plant. Two scenarios are investigated: the simultaneous failure of two filters and disturbances in the flow and density of the thickener. The simulation results show that the proposed control strategy could extend the period of operation of the dewatering plant under failures in the disc filters and reject significant disturbances. For the considered simulation period, the proposed solution increases the time to overflow by 72% when compared to the previous control strategy. Thus, it is possible to avoid the waste of approximately 2448.36 tons of ore pulp that would be sent to the tailings dam.

Local drivers of heterogeneity in a tropical forest: epiphytic tank bromeliads affect the availability of soil resources and conditions and indirectly affect the structure of seedling communities.

Environmental heterogeneity is a key component in explaining the megadiversity of tropical forests. Despite its importance, knowledge about local drivers of environmental heterogeneity remains a challenge for ecologists. In Neotropical forests, epiphytic tank bromeliads store large amounts of water and nutrients in the tree canopy, and their tank overflow may create nutrient-rich patches in the soil. However, the effects of this nutrient flux on environmental heterogeneity and plant community structure in the understory remain unexplored. In a Brazilian coastal sandy forest, we investigated the effects of the presence of epiphytic tank bromeliads on throughfall chemistry, soil chemistry, soil litter biomass, light, and seedling community structure. In the presence of epiphytic tank bromeliads, the throughfall nitrogen concentration increased twofold, the throughfall phosphorus concentration increased threefold, and the soil patches had a 3.96% higher pH, a 50% higher calcium concentration, and 11.88% less light. By altering the availability of soil resources and conditions, the presence of bromeliads partially shifted the available niche spaces for plant species and indirectly affected the structure of the seedling communities, decreasing their diversity, density, and biomass. For the first time, we showed that the presence of tank bromeliads in the canopy can create characteristic soil patches in the understory, affecting the structure of seedling communities via fertilization. Our results reveal a novel local driver of environmental heterogeneity, reinforcing and expanding the key role of tank bromeliads both in nutrient cycling and plant community structuring of Neotropical coastal sandy forests.

Characteristics of overflow pollution from combined sewer sediment: Formation, contribution and regulation

Sewer sediments contain high concentrations of carbon, nitrogen, and phosphorus pollutants, which can be the main source of overflow pollution due to high-velocity scouring. To elucidate the scouring overflow pollution characteristics and regulation mechanism of sewer sediment under different precipitation intensities, a sewer-storage tank linkage control experimental device was established to simulate the practical sewer overflow under different precipitation intensities and the control process of storage tank overflow pollutants. Based on the division of flow from small to large, the pollution characteristics of overflow pollutants and the contribution rate of sewer sediments to overflow pollutants were analysed. The results showed that the total load of overflow pollutants increased with an increase in rainfall intensity and were 7.58 kg, 16.54 kg, 27.42 kg, respectively. The concentration of particulate pollutants increased sharply in a short time, and the concentration of dissolved pollutants decreased at a certain dilution. Sewer sediment was the main source of overflow pollutants, contributing up to 70%. After the overflow pollutants entered the regulation and storage tank, a certain stratification phenomenon was discovered at different sedimentation times. The concentration of large particle pollutants gradually increased from top to bottom in the regulation and storage tank, and the concentration of dissolved pollutants showed no obvious difference between the layers. With an increase in rainfall intensity, the recommended regulation and storage times of overflow pollutants were within 15 min, 45–60 min, and 60 min, respectively. Finally, based on the relationship among rainfall intensity, sediment scouring thickness, regulation and storage time, a prediction formula for the regulation and storage time of overflow pollutants was obtained, which provided a basis for the regulation and treatment of subsequent overflow pollutants.

Water Level Detection and Monitoring Using Arduino

Most of the individuals in residential areas experience the problem of running out of water and overflow tanks. It becomes more difficult for the consumer to gauge the amount of water in the tank. When the pump is ON, the user will not realize that the water tank is filled, which may result in an overflow. Auto water pump switch is used to troubleshoot problems with the water tank. The consumer can use this technology to fill an empty tank without having to take any effort. When the tank is empty, the system automatically turns ON, and when the tank is filled, it automatically turns OFF. Water is not wasted with this technique

Risk Assessment of Petroleum Products Loading Arm by BTA Technique

Background: Loading of petroleum products consists of several parts, of which the arm platform section is known to be the source of most accidents. Objectives: Therefore, this study was done to evaluate the risk of arm loading platforms using the bow-tie analysis (BTA) technique to identify the causes and the probability of occurrence of hazardous events. Methods: In this study, we first identified the risks of the loading arm using the expert’s judgment. The risk of overflow is considered as the top event. Then, the basic events were identified by the fault tree analysis (FTA), and the possible consequences of the top event were predicted using the event tree. Next, using the computational equations, the probability of spillover and its consequences were calculated. The path of the risk event from the causal phase to the consequent phase was also illustrated by sketching the structure of the BTA. Results: A total of 14 basic events and 8 intermediate events were involved in the occurrence of the top event, and 5 consequences were identified for the risk of spillover. The probability of the top event occurring was calculated to be 3.12 × 10-7. Conclusions: According to the results of this study, tank overflow is one of the most important hazards in the loading arm section.

An A Useful Model for Rainwater Catchment System Design

Choosing a storage volume size for a rainwater catchment project is difficult because the overall volume needs to be large enough to meet the demand of users but not so high that it is never completely filled, which would waste money and space in the community. This newly developed Excel-based model can simplify choosing appropriate tank sizes for a rainwater catchment project by projecting the water availability in storage at multiple locations over the course of a year. For ease of use, the user can input monthly data or daily data for improved accuracy. This tool also incorporates the ability to include adjustable daily demand, to distribute demand over multiple structures, to account for tank overflow, and to increase demand at other locations if one of them runs out of water. The water level at each location over one year and the local storage volume are shown on a plot, making it easy to determine what storage volume is necessary to provide enough water for the community. This tool was originally developed to determine appropriate storage volumes for a rainwater catchment project in Mkutani, Tanzania and has been adapted for general use.

New Risk Assessment Method of Gas Influx Based on Fifteen Example Wells

With the increase of global deepwater drilling, the scale of the deepwater drilling contract market continues to expand, and the depth of the drilling operations constantly refreshes the record. At the same time, the drilling environment and related geological conditions becomes more and more complex, which leads to the increase of the risk in the operation of deepwater drilling. After the happening of “Deepwater Horizon Accident” in the Gulf of Mexico, the prevention and control of blowout has become an urgent problem to be solved in the development of offshore oil and gas. Dealing with the problem of overflow and blowout in deepwater drilling, the most effective technical measures are based on early detection and identification of gas influx. The research on the degree of gas invasion is the basis of the formulation and implementation of well control measures. In this paper, a simulation model of gas-liquid two-phase flow after the happening of gas influx is established to calculate the cross section gas content, mud tank overflow, and bottom-hole pressure. Through the calculation, the real-time quantitative relationship between the characterization of the gas content and the bottom-hole pressure and the increment of the mud pool was established, and then the realtime quantitative degree of gas invasion is analyzed.

Puncture of an import gasoline pipeline—Spray effects may evaporate more fuel than a Buncefield-type tank overfill event

This paper is concerned with evaporation of moderately volatile liquids, gasoline in particular, due to spray generation, liquid fragmentation and fountain effects following accidental puncture of a pressurized pipeline. Hazard analysis predicts that extensive evaporation will take place. The paper examines a typical fuel depot receiving gasoline from a ship at a nearby port via an above-ground pipeline. For comparative purposes, two types of accidental release during import are considered: 1) The receiving tank overflows in a worst-case Buncefield-type event (baseline). 2) The import pipeline is punctured and a jet of liquid discharges upwards.The paper examines pipeline import of three substances, hexane, octane and winter gasoline. Hazard analysis using the PHAST software suite indicates that the amount of fuel evaporated from the pipeline puncture scenarios greatly exceeds the amount evaporated in a tank overfill event for all three substances, gasoline in particular. Proper modelling of evaporation of wide-range multi-component mixtures such as gasoline is challenging however. PHAST's simplified thermodynamic modelling of properties of mixtures may be a source of error. A PHAST-based stand-alone spray evaporation model with advanced thermodynamic capability is developed. Results indicate that PHAST does indeed overestimate evaporation of mixtures. Still, model output shows that evaporation following pipeline puncture may exceed the evaporation from a Buncefield-type tank overfill event by a factor of two or more. This finding is significant as evaporation from pipeline puncture scenarios appear largely overlooked in hazard analysis. The finding may lead to a fundamental re-appraisal of the hazard potential of fuel depots and pipelines.

Understanding the Impact of Mesh on Tank Overflow System Capacity

A 2016 incident that resulted in damage to a water storage tank's roof motivated pilot-scale experiments to be conducted to determine the impact of mesh on tank overflow capacity. A clean mesh installed near the outlet of an overflow system did not reduce the capacity during the weir dominated flow regime. The impact of a mesh was found to be a reduction in the area available to flow, which was found to lower the achievable capacity through the system. Considering only the head loss or pressure drop associated with the mesh and not area reduction resulted in an overestimation of achievable capacity, which could lead to an undersized overflow system. The results and formulas presented will help water utilities ensure overflow systems with mesh are appropriately sized.

Methane and nitrous oxide cycling microbial communities in soils above septic leach fields: Abundances with depth and correlations with net surface emissions

Onsite septic systems use soil microbial communities to treat wastewater, in the process creating potent greenhouse gases (GHGs): methane (CH4) and nitrous oxide (N2O). Subsurface soil dispersal systems of septic tank overflow, known as leach fields, are an important part of wastewater treatment and have the potential to contribute significantly to GHG cycling. This study aimed to characterize soil microbial communities associated with leach field systems and quantify the abundance and distribution of microbial populations involved in CH4 and N2O cycling. Functional genes were used to target populations producing and consuming GHGs, specifically methyl coenzyme M reductase (mcrA) and particulate methane monooxygenase (pmoA) for CH4 and nitric oxide reductase (cnorB) and nitrous oxide reductase (nosZ) for N2O. All biomarker genes were found in all soil samples regardless of treatment (leach field, sand filter, or control) or depth (surface or subsurface). In general, biomarker genes were more abundant in surface soils than subsurface soils suggesting the majority of GHG cycling is occurring in near-surface soils. Ratios of production to consumption gene abundances showed a positive relationship with CH4 emissions (mcrA:pmoA, p < 0.001) but not with N2O emission (cnorB:nosZ, p > 0.05). Of the three measured soil parameters (volumetric water content (VWC), temperature, and conductivity), only VWC was significantly correlated to a biomarker gene, mcrA (p = 0.0398) but not pmoA or either of the N2O cycling genes (p > 0.05 for cnorB and nosZ). 16S rRNA amplicon library sequencing results revealed soil VWC, CH4 flux and N2O flux together explained 64% of the microbial community diversity between samples. Sequencing of mcrA and pmoA amplicon libraries revealed treatment had little effect on diversity of CH4 cycling organisms. Overall, these results suggest GHG cycling occurs in all soils regardless of whether or not they are associated with a leach field system.

An Analytical Stochastic Approach for Evaluating the Performance of Combined Sewer Overflow Tanks

AbstractStorm water detention tanks are widely used for the control of combined sewer overflows. Conventional continuous simulation and recently developed analytical probabilistic models have been used for analyzing the hydrologic operation of storm water detention tanks. These analyses are necessary in order to accurately estimate the runoff capture efficiency of a given control system or the required storage capacity for achieving a desired runoff capture efficiency. The analytical probabilistic models still have the shortcomings of making simplifying assumptions about the initial storage conditions of a detention tank. Developed in this study is a new stochastic analysis method which can provide similar results as provided by continuous simulations and overcome some of the shortcomings of the previously developed analytical probabilistic models. This stochastic analysis method uses closed‐form analytical equations to estimate the runoff capture efficiency and required storage capacity. Results from these analytical equations are validated by comparing with continuous simulation results and close agreements are observed. These analytical equations are therefore proposed as a computationally efficient alternative for analyzing the hydrologic performance of combined sewer overflow tanks.

Composite disturbance rejection control for hydraulic classification

In the hydraulic classification, precise control for the flow rate of overflow water is vital to guarantee the uniformity and stability of the powder product size. Usually the multiple overflow tanks are supplied by a shared overflow pipeline, which gives rise to large coupling effects in the controls for the flow rates of multiple overflow tanks simultaneously. To solve this issue, it is necessary to keep the water pressure in the shared overflow pipeline accurately constant, which is not easy due to strong disturbances. Several control strategies have been proposed to control the constant water pressure. However, most of them (such as proportional-integral-derivative and model predictive control) reject disturbances just through feedback regulation and do not reject disturbances directly. This may cause poor control performances in the presence of strong disturbances. For improving the disturbance rejection performance, a control scheme based on proportional-integral-derivatives and disturbance observer is put forward in this paper. The scheme employs disturbance observer as feedforward compensation and a proportional-integral-derivative controller as feedback regulation. The disturbance rejection properties under both model mismatches and external disturbances are discussed. The test results illustrate that the proposed method can remarkably improve the disturbance attenuation property compared with the conventional proportional-integral-derivative method in the hydraulic classification process.

Automatic Water Tank Filling System Controlled Using ArduinoTM Based Sensor for Home Application

Water supply is the most important thing in daily home activity especially for washing, cleaning, and taking a bath. The Indonesian villagers commonly supply the water by pumping the groundwater to fill a water tank. However, the utilization of non-automated switch used to turn on and turn off a pumping machine sometimes causes either the water spills or a wasteful electrical consumption. The previous works reported the utilizations of ArduinoTM based sensors for plant watering system, water tank overflow control, and automated irrigation system. In this work, an automated water tank filling system will be proposed. The system is designed by applying an ultrasonic sensor, an automatic switch module, a water-flow sensor, an ArduinoTM microcontroller, and a pumping machine in order to automatically switch the water filling. By applying an ultrasonic sensor, an ultrasonic transmitter is mounted on the top of the tank and transmits an ultrasonic pulse down into the tank. This pulse which travels at the speed of sound will be reflected back to the transmitter from the liquid surface. The time delay measurement between transmitted and received signals enables the device to calculate the distance to the surface. The transmitter is programmed to automatically determine the liquid level and switch the pumping machine. The dynamics of water flow and liquid level during filling and draining the water tank will be reported. We hope to this system, people will enjoy supplying water without their worries related to water spills and a wasteful electrical consumption.

Assessing Nutrient, Biomass, and Sediment Transport of Drainage Ditches in the Three Gorges Reservoir Area

The contributions of drainage ditches to the accelerated eutrophication of rivers have rarely been assessed, especially for the Three Gorges Reservoir (TGR) drainage ditches. Forty drainage ditches in the TGR from multiple land use types were extensively investigated for 10 parameters of water quality. The results showed that the concentrations of total nitrogen (TN) and total phosphorus (TP) in the TGR drainage ditches were generally far higher than the internationally recognized eutrophication threshold. Based on this study, both ditch water and sediments from residential land and roadside land had the highest concentrations of nutrients. Possible sources of these nutrients include sewage water and septic tank overflow. Forestland had significantly lower concentrations of nutrients. Residential ditches had higher values of electrical conductivity (EC) and total dissolved solid (TDS) values and lower dissolved oxygen (DO) concentrations. Forestland had lower values of EC and TDS values and higher DO concentrations. The results indicate that the nutrients that have accumulated in the sediments have significant impacts on the water quality in adjacent ditches. A long‐term plan must be developed to more strictly control the external loading of nutrients from surrounding land. Action plans to promote the growth of wetland plants in drainage ditches are important for increasing agrochemical retention in the TGR drainage ditches. TGR drainage ditches from residential zones must be actively managed by cleaning and sediment removal to control the risk of nutrients being released into the reservoir.

Holistic risk assessment of surface water contamination due to Pb-210 in oil produced water from the Bakken Shale

A holistic risk assessment of surface water (SW) contamination due to lead-210 (Pb-210) in oil produced water (PW) from the Bakken Shale in North Dakota (ND) was conducted. Pb-210 is a relatively long-lived radionuclide and very mobile in water. Because of limited data on Pb-210, a simulation model was developed to determine its concentration based on its parent radium-226 and historical total dissolved solids levels in PW. Scenarios where PW spills could reach SW were analyzed by applying the four steps of the risk assessment process. These scenarios are: (1) storage tank overflow, (2) leakage in equipment, and (3) spills related to trucks used to transport PW. Furthermore, a survey was conducted in ND to quantify the risk perception of PW from different stakeholders. Findings from the study include a low probability of a PW spill reaching SW and simulated concentration of Pb-210 in drinking water higher than the recommended value established by the World Health Organization. Also, after including the results from the risk perception survey, the assessment indicates that the risk of contamination of the three scenarios evaluated is between medium-high to high.