Leakage Of Hazardous Chemicals Research Articles

Quantitative Risk Assessment of an Oil-Gas-Hydrogen-Electricity Integrated Energy Station in China.

This paper presents a quantitative risk assessment (QRA) study of an oil-gas-hydrogen-electricity integrated energy station in China. A comprehensive assessment of the station was made in terms of consequences and risks, respectively. Consequence analysis shows that the severity of hazardous chemical leakage accidents in the station is in the order of natural gas, hydrogen, gasoline, and diesel fuel, especially in the liquefied natural gas (LNG) and compressed natural gas (CNG) storage tank areas, which may cause major accidents in the event of leakage. The results of the risk assessment showed that the individual and societal risks of the integrated oil-gas-hydrogen-electricity energy station exceeded the risk acceptance criteria. Moreover, the catastrophic rupture of LNG and CNG storage tanks is the main cause of the unacceptable risk. Additional mitigation measures for them, mainly including the installation of emergency manual shut-off valves, the installation of combustible gas detection and alarm devices, and pressure relief protection devices, can effectively reduce the risk to an acceptable level.

Estimation of the Hazardous Chemical Leakage Scale Inside Buildings Using CFD

Increased industrialization and aging infrastructure have resulted in leaks of hazardous chemicals, such as CO. Leak modeling is crucial to developing emergency response strategies. Therefore, we simulated the time to criticality (TTC), which is the time to reach the threshold limit for occupational exposure, of a CO leak. The basis of the study is a fire dynamics simulator, a computational fluid dynamics model that was used to investigate the movement of CO in various scenarios, including using different building layouts and areas, temperatures, and leak diameters. Multiple regression analysis was performed to obtain regression equations for the TTC as a function of the independent variables. Ultimately, we found that the type of dispersion varies with respect to the temperature-dependent density of CO, and, among the independent variables, the leak diameter had the strongest effect on the TTC. The regression equations with logarithmic conversion were validated and found to have higher accuracy than those without logarithmic conversion. The findings provide useful information for developing emergency response plans regarding leak size in the case of hazardous chemical leakage. However, empirical studies of different gas types and leakage scenarios are required.

Quantitative assessment of human error of emergency behavior for hazardous chemical spills in chemical parks

In-depth research on human error is of great significance to improve the human reliability in the emergency rescue as well as to avoid the occurrence of secondary accidents. Therefore, the standardized process and key emergency behaviors in the emergency rescue process of hazardous chemical leakage accidents are first analyzed. Based on the Cognitive Reliability and Error Analysis Method, the human error mode was sorted out, and the human error probability estimation model was established. Combining the improved Analytic Hierarchy Process and entropy weight method, a model for estimating the severity of human error was established, realizing the quantitative analysis of the human reliability of the emergency behavior. The study showed that the 21 emergency behaviors were clustered into 3 categories, with clustering 1 including 2 emergency behaviors, which have the highest level of severity, clustering 2 including 11 emergency behaviors, and clustering 3 including 8 emergency behaviors. Finally, countermeasures were proposed in four areas, including increasing the level of Common Performance Conditions and the ability to transmit information on accidents, etc. It indicates that the method can widely guide the improvement of emergency response capability in chemical parks.

An integrated risk assessment method for urban areas due to chemical leakage accidents

Chemical parks which hold large inventories of hazardous materials have become one important type of urban critical infrastructure. The hazardous chemical leakage such as toxic gas leakage has emerged in recent years, resulting in not only serious environmental pollution but also catastrophic consequences to certain urban areas. It is critical to make scientific risk assessment for such events to reduce negative effects. To address this issue, an integrated urban risk assessment (IURA) method coupling consequences of chemical leakage accidents and the vulnerability of local population is proposed in this work. The threat zones and hazard maps of toxic gas dispersion are present by using the ALOHA software. The population vulnerability is decided by three indicators including exposure, sensitivity, and adaptive capacity of residents in affected areas, the Grey Correlation-TOPSIS (GC-TOPSIS) method is used to rank the vulnerability of different regions. The ArcGIS software is applied to generate an integrated risk map through superimposing the hazard map and the population vulnerability map. The original risk matrix evaluation results were subdivided using the Borda count method. A case about an industrial city in Hubei, China is analyzed to test the method. Result shows the new integrated risk assessment method is more accurate and effective, which is beneficial for the government to develop emergency plans and enhance the safety of people.

An advanced gas leakage traceability & dispersion prediction methodology using unmanned aerial vehicle

Rapid prediction of gas leakage traceability & dispersion (GLTD) is critical for the emergency management of chemical industrial parks (CIPs). Existing GLTD prediction methods are limited by the spatial coverage and number of fixed gas sensors. It is also not possible to provide any specific information about the leak scene. Inspired by emerging drone technologies, this work proposed an advanced UAV-driven GLTD prediction methodology. The dispersion concentration field of the hazardous chemical leakage is simulated based on an improved Gaussian plume model, and then high precision and efficiency prediction is achieved by an improved sparrow search algorithm (ISSA), which can periodically update the flight strategy of UAVs. The proposed methodology is validated by a case study of a CIP in China. The results indicate that, compared with the traditional fixed sensors-driven strategy based on PSO, GA and SSA, the involvement of UAVs based on ISSA can reduce the prediction errors by 86.7%, 88.2% and 53.4%. Further analysis is conducted on the impact of algorithm parameters (UAV locations, number of UAVs, sampling frequency and step size) on search efficiency. The optimal algorithm parameters are discussed from the perspectives of cost effectiveness and computational efficiency. This work has the potentials to assist in constructing an intelligent emergency decision support system for CIPs.

Flame retardant, heat insulating and hydrophobic chitosan-derived aerogels for the clean-up of hazardous chemicals

Leakage of hazardous chemicals often causes significant casualties, enormous economic losses, and negative social benefits. Presently, fire rescue personnel lack efficient and eco-friendly disposal materials for hazardous chemical leakage accidents. In this study, chitosan (CS) aerogels with excellent flame-retardant performance were prepared via cross-linking by two phosphorus-containing vanillin-based compounds (DV and TV). The as-prepared chitosan aerogels were lightweight and porous. The introduction of DV and TV greatly enhanced the residual char yields of CS at 700 °C and the flame-retardant performance of chitosan aerogels. TCS-5.0 possessed the best flame-retardant performance, indicating that TV was more effective than DV in enhancing the flame-retardant performance of chitosan aerogels. The greatly improved flame-retardant properties could be attributed to TV effectively promoting the residual char formation of chitosan aerogels and reducing the formation of combustible gas phase products. To improve the hydrophobicity of chitosan aerogels, TCS-5.0 was treated with solution immersion to load siloxane molecules on its surface. The water contact angle of HTCS-5.0 was 136.1°. HTCS-5.0 had a high oil absorption multiplicity, absorbing up to 31 times its own weight of chloroform. HTCS-5.0 could continuously absorb organic solvents on the water surface with the assistance of a vacuum pump, indicating that HTCS-5.0 could be used for the clean-up of hazardous chemical leakage accidents.

Flexural behavior of fiber reinforced composites sandwich panels with a reused wooden core

The increasing use of wood products has inevitably resulted in a fast accumulation of waste wood, which is commonly landfilled or recycled for energy or products with low added value. In the present study, a concept has been adopted to reuse the waste wood formwork as the core of FRP sandwich panels. The waste wood formwork has been firstly sliced into wood strips of a specific width, which are then flipped by 90o and bonded together to form a plate as the sandwich core. Such a recycling routine appears as a promising method due to (1) minimum pre-treatment for processing the waste wood; and (2) less likelihood of the hazardous chemicals leakage because of the covered GFRP skins. The flexural behavior of such sandwich panels has been evaluated through a series of three-point bending tests with the thicknesses of GFRP layer and the core plate as the main parameters. The test results indicate that the GFRP-waste wood sandwich panels failed by either rupture of the tensile GFRP sheet or crushing of the compression side. The bending stiffness and flexural strength improves with the increase in the thicknesses of the core plate and GFRP layer, and the panels with three-layer GFRP sheets have the bending stiffness and flexural strength up to 11.0 and 4.4 times higher than that of the core plate. The analytical and numerical predictions on the flexural properties of the sandwich plate show in good agreement with that from the tests, validating the adopted the models.

Mg(TFSI)2-Based Solid-State Eutectic Electrolyte Towards Safer Magnesium Batteries

Magnesium (Mg) batteries are regarded as safer alternatives for Li+-dominated batteries by virtue of the unique dendrite-free property of Mg element. However, traditional liquid electrolytes applied in Mg batteries are mainly based on chloride salts and highly flammable organic solvents, which might cause numerous safety issues such as fire, electrochemical corrosion, and leakage of hazardous chemicals. These kinds of electrolytes seriously violate the original purpose of developing Mg-based batteries. Therefore, exploring non-flammable chloride-free solid-state electrolytes is of significant importance for realizing safer Mg batteries. Here in this work, a novel non-flammable eutectic electrolyte based on chloride-free Mg(TFSI)2 salt is first proposed as a solid electrolyte for safer Mg metal batteries. Our recent results demonstrate that compared with traditional Mg(TFSI)2-based electrolytes which dissolve in flammable organic solvents such as EC, PC, and THF solvent, this Mg(TFSI)2-based eutectic solid electrolyte is non-flammable with robust mechanical structures. When applied in Mg//Mg symmetric batteries, this novel eutectic solid electrolyte could greatly suppress the overpotential phenomenon that occurs in traditional Mg-based electrolytes and achieves stable Mg plating/stripping reversibility with more than 150 h. Furthermore, the practical feasibility of this eutectic solid electrolyte is also demonstrated in Mg//V2O5 full cell, which shows competitive electrochemical performance. We believe that the research on such new electrolytes could provide a new strategy for developing safe and sustainable Mg-based batteries.

Prediction Method for Leakage Probability of Typical Fluid Machinery & Pipeline based on Cloud Model

Many dangerous chemicals are involved in the operation of fluid machinery, and the leakage of hazardous chemicals could trigger serious accidents, so the leakage probability prediction of fluid machinery and the effective maintenance before the equipment breakdowns are the critical factors in preventing accidents. A leakage probability prediction method based on a cloud model is proposed to aim at the standard fluid machinery with a frequent leakage probability in a chemical industry park. Due to the basic leakage probability of fluid machinery at home and abroad, the index system of leakage influencing factors is constructed and its influence degree is analysed. The modified typical fluid machinery leakage probability is then obtained using the cloud model to eliminate the subjectivity of quantitative results. The proposed method is utilized to estimate the leakage probability of Ethylene pipeline leakage of a pump in 1300# cracking gas compression area. The outcome 4.27 × 10−5 proves that this method can effectively solve the deviation problem in the leakage prediction process of domestic fluid machinery and guide the process of leakage probability prediction or accident prevention.

A Quantitative Risk Assessment Model for Domino Accidents of Hazardous Chemicals Transportation

In recent years, hazardous materials transportation accidents have received increasing attention. Previous studies have focused on accidents involving a single vehicle. When vehicles loaded with materials gather on a stretch of road, a potential domino accident might cause terrible incidents. This paper prompts a quantitative risk assessment (QRA) model to estimate the risk of multi-vehicle incidents. The model calculates the possibility of leakage and explosion of hazardous chemicals using a dynamic Bayesian network (DBN). For different types of hazardous chemicals, the model uses event trees to list different scenarios and analyzes the probability of domino accidents caused by each scenario. The FN-curve and potential loss of life (PLL) are used as an index to evaluate social risk. A case involving multiple vehicles in the JinShan District, Shanghai, is analyzed. The result of the case shows that the state of the driver, the type of road, weather factors and the distance between vehicles have vital impacts on the societal risk resulting from hazardous materials transportation accidents.

Simulation of scenario characteristics of LPG tank explosion accident and its contribution to emergency planning: A case study

Leakage and explosion of hazardous chemicals during road transportation can cause serious building damage and casualties, and adoption of highly-efficient emergency rescue measures plays a critical role in reducing accidental hazards. Considering a liquefied petroleum gas (LPG) transport tanker explosion accident that occurred in Wenling, Zhejiang Province, China on June 13, 2020 as example, this study proposes a risk assessment framework. This framework recreates the leakage and explosion of the accident process using FLACS v10.9, suggests plans for evacuation, describes the rescue areas of different levels, and explores the influence of environmental factors on the evacuation and rescue areas. The results show that simulated and predicted distributions of fuel vapour cloud concentration and explosion overpressure can provide a reference basis for rapid rescue activities; the characterization of the dynamic effects of wind speed, wind direction, and temperature with respect to the evacuation and rescue areas can be used as theoretical support for on-site adjustment of rescue forces. The role of obstacles can prevent the expansion of the evacuation areas under low wind-speed conditions, and the presence of highly congested obstacles determines the level of the rescue area. The results obtained are important for the risk analysis and the development of emergency rescue measures in case of explosion accidents associated with transportation of hazardous chemicals on high-hazard and high-sensitive road sections.

Comparative study on numerical simulation based on CALPUFF and wind tunnel simulation of hazardous chemical leakage accidents

CALPUFF, as a Lagrangian puff modeling system, is mostly used in the field of atmospheric environment research and risk assessment. CALPUFF performs well for short-term and short-range release scenarios over complex terrain, as well as long-term and long-range transportation. Therefore, this article uses the CALPUFF model to simulate a toxic gas leakage accident in a hazardous chemical plant in an urban area, focusing on the influence of local buildings. Wind tunnel experiments are performed in accordance with the CALPUFF experiments to assess the model’s accuracy in cases of chemical leakage accidents. The results of the wind tunnel experiment are superimposed on the map of CALPUFF calculation, and the quantitative analysis is also performed. The comparative results show that the simulation results of the CALPUFF are mainly affected by factors such as wind direction, wind speed, and the complexity of the surface environment. With less influence of buildings, such as the south and north wind, the CALPUFF simulation is consistent with the wind tunnel experiment, having a correlation coefficient of over 0.7 in most cases, while under the east wind, the consistency is significantly lower due to the influence of buildings. In addition, it is found that the wind tunnel experiment is more accurate in the near field of the pollution source, while CALPUFF is more suitable for simulating the overall trend of gas dispersion. The comparison and evaluation of the capabilities of different methods on gas dispersion simulation are helpful in guiding the emergency response during hazardous chemical leakage accidents.

Internal diffusion and re‐emission of leaked liquid ethyl acetate from mortar materials

AbstractAssuming the leakage of hazardous liquid chemicals in factories and chemical plants caused by natural disasters or human error, it is important to precisely estimate exposure risk and design appropriate evacuation plans and risk‐reduction measures. The exposure risk of indoor residents to leaked chemicals may be estimated using direct measurements or theoretical/numerical estimations of gas‐phase concentrations. Although mathematical models of gas‐phase concentration in the workplace are essential for predicting exposure concentrations at the design stage, practical models have not yet been fully established. We previously proposed practical numerical models to assess indoor gas‐phase concentration distributions after the accidental leakage of liquid chemicals using liquid toluene as a representative hazardous chemical. In this study, the leakage of liquid ethyl acetate, a commonly used organic solvent, into mortar flooring was reproduced in a small test chamber, and numerical analysis was performed. The results showed that the time history of the chamber exhaust concentration had a sharp peak and differed significantly from that of toluene. Three‐dimensional computational fluid dynamics (CFD) analysis incorporating practical ethyl acetate emission models reproduced the external and internal emission characteristics of leaked ethyl acetate on the mortar material. The models showed reasonable agreement with the experimental data.

Application of modified Gaussian plume algorithm in hazard assessment of toxic chemicals in nuclear power plants

The leakage or explosion of hazardous chemicals will seriously affect the operation safety of nuclear power plants. Therefore, in the nuclear safety review, it has been clearly proposed that the environmental risks of off-site toxic chemicals should be evaluated. When calculating the toxic chemical leakage accident, as HABIT model calculation result is based on the 2 min concentration limit condition assumed in RG1.78, and the longest duration is only 7.5 min, so it cannot be applied to the safety assessment of offsite toxic hazards. This paper presents a detail analysis of the impact on toxic chemical release using modified Gaussian plume algorithm model in ALOHA. The Gaussian plume algorithm is mainly used to calculate the plume diffusion emitted by continuous point sources, assuming that its concentration distribution obeys the empirical model of normal distribution. The plume is transported downwind at an average wind speed, ignoring turbulent diffusion downwind, with vertical and horizontal lateral diffusion described by diffusion parameters. The Gaussian plume algorithm has many advantages such as high computational efficiency and simple calculation method. Therefore, it has a wide application in the field of atmospheric diffusion. Calculation shows for the chlorine and ammonia leakage accident, chlorine’s influence area is much larger than ammonia. For ammonia, safe distance is about 3.5 km, but for chlorine, hydrogen fluoride and hydrazine, with the increase of storage capacity, their safety distance change slower at 8 km, which is consistent with HAD101/04. The storage amount of liquid ammonia shows an exponential increase, indicating that for liquid ammonia, the chemical safety control distance will not exceed 3.5 km. Conclusion of this paper has a long last meaning to NPP environmental assessment and safety evaluation, and full filled area of toxic chemicals quantitative analysis.

Numerical models for seamlessly predicting internal diffusion and re-emission of leaked liquid toluene from indoor mortar materials

There have been serious hazardous liquid chemical leakage cases in factories, chemical plants, and laboratories owing to natural disasters or contingent human accidents. Regarding risk management, when high-risk liquid chemical substances are assumed to leak inside enclosed indoor spaces, reasonable prediction of transient and heterogeneous concentration distributions formed around the human body is necessary to develop an appropriate evacuation plan. In particular, understanding the air-phase concentration level in the breathing zone and its duration for inhalation exposure is essential for short-term and high-concentration exposure health risk assessment. Transient and non-uniform concentration distributions can be predicted using computational fluid dynamics (CFD) and in silico human body analysis. However, the development of practical chemical emission models considering internal diffusion and direct evaporative diffusion from floor materials and their seamless boundary conditions must be addressed for practical application. In this study, liquid toluene was assumed to be a representative hazardous chemical substance for risk assessment, and fundamental experiments and corresponding numerical analyses of liquid toluene leaks on mortar materials were conducted. The experimental results suggest that the effective diffusion coefficient of the mortar sample has a significant effect on the sorption timescales of liquid toluene into the materials and significantly changes the air-phase toluene concentrations. The three-dimensional CFD analysis incorporating the practical toluene emission models reproduces the external and internal emission characteristics of leaked toluene on the mortar material and reasonably agrees with the experimental data.

Sudden deaths due to accidental leakage of Lindane from a storage tank in a village, Sitapur, Uttar Pradesh, India, 2020: A field epidemiological investigation.

Background:Chemical leakages cause devastating health effects on humans. On 6 February 2020, seven deaths were reported following a hazardous chemical leakage in a village in Uttar Pradesh, India. We investigated the event to identify the cause and propose recommendations.Methods:We defined a case as sudden onset of breathlessness, headache, or death in the village, 6–7 February 2020. We conducted a house-to-house case search and calculated attack rate (AR) and case-fatality rate (CFR) by age and gender. We conducted an environmental investigation at the leakage site and sent the chemicals for forensic analysis. We obtained the cause of death through autopsy reports.Results:Out of 2,942 residents, we identified 23 cases (AR = 8/1,000) and seven deaths (CFR = 30%). The median age of the case was 42 years (range, 2–64 years). The AR was higher among males (14/1,000 [19/1,402]). All the 23 case-patients who were sleeping at the chemical leakage site or visited to witness the event developed symptoms, and all seven cases who were sleeping within 150 meters of the leakage site died. The environmental investigation revealed leakage of hazardous substances from the storage tank. Toxicology analysis confirmed the leaked chemical as Lindane (gamma-hexachlorocyclohexane), and autopsy reports confirmed the cause of death as asphyxia.Conclusions:Asphyxia following the leakage of Lindane from the storage tank possibly led to sudden deaths. We recommend using leak-proof tanks to ensure safe storage and disposal, law enforcement, and regulations to prevent people from staying close to chemical storage sites.

Design of Constructed Wetland Treatment Measures for Highway Runoff in a Water Source Protection Area

Road runoff contains high levels of pollutants, such as heavy metals and hydrocarbons. If they are directly discharged into sensitive water bodies, they will cause irreversible pollution and damage to the water environment. Furthermore, the leakage of hazardous chemicals into sensitive waters will lead to serious consequences, so determining how to deal with road surface runoff has become an urgent problem. This research adopts a scheme for collecting and processing road runoff in a water source protection area using artificial wetlands. After optimizing and improving the general vertical flow of the wetland structure, a composite wetland structure and a relatively novel tandem wetland structure are proposed. An indoor model is established for experiments on various main wetland structure schemes. The results show that the two newly proposed wetland structures improve the possibility of water level control in general vertical flow structures. At the same time, the movement distance of the water flow in the wetland structure is changed to improve the treatment effect of runoff. The removal effect of composite and tandem wetland structures for heavy metals, petroleum substances, and COD (chemical oxygen demand) is significantly better than that of general vertical flow structures. Among them, the composite structure is better than the tandem structure at removing heavy metals, petroleum substances, and COD. However, due to the water discharge method of the structures, the latter has a better effect than the former in the treatment of suspended substances.

Disaster Healthcare Workers' Experience of Using the Psychological First Aid Mobile App During Disaster Simulation Training.

The study aimed to examine the experience of disaster healthcare workers with simulation training using the Psychological First Aid (PFA) mobile app. This study was designed using qualitative research methodology with focus group interviews. The participants were 19 disaster healthcare workers from community mental health service centers who attended disaster simulation training in flood, fire, or leakage of hazardous chemicals. Before the simulation, participants were provided the PFA mobile app and allowed to practice the PFA techniques to apply them during the simulation. Data were collected through focus group interviews and qualitatively analyzed using the content analysis method. The findings were divided into 6 categories: experience in realistic disaster situations, satisfaction with education methods using a mobile app, effectiveness of the PFA app in disaster relief, confidence in disaster relief by integrating experience and knowledge of the PFA app, self-reflection as a disaster healthcare worker, and identifying limitations and making developmental suggestions. Based on the participants' developmental proposals in this study, the disaster simulation training, incorporating improvements in the disaster simulation training and the PFA app features, will serve as a new framework for disaster support education and systematic mental health services to survivors by disaster healthcare workers.

Design of Intelligent Early Warning Robot System for Warehouse Autonomous Patrol based on Scale Estimation Algorithm of Probability Theory

In view of the backward monitoring status in the traditional safety management of hazardous chemicals warehouse, a patrol robot for hazardous chemicals warehouse with autonomous patrol stereo detection, intelligent early warning and remote monitoring functions is designed, and the design process of related functions of autonomous patrol navigation subsystem, environmental detection subsystem and remote monitoring subsystem is discussed from two aspects of hardware and software. Because both the camera and the target may be in motion, it is necessary to consider the scale change of target influence caused by relative distance. In order to overcome the shortcoming of invariable scale in Mean Shift algorithm, this paper adopts a scale adaptive method to estimate the size of the target, adjusts the parameters of kernel function by using ellipse feature, and takes the parameters of the current frame as the initial data of the next frame, so as to achieve the effect of adaptively adjusting the target scale. The test results show that the system can effectively traverse the map of hazardous chemicals warehouse, accurately assess the leakage of hazardous chemicals and the environmental safety of warehouse, and give early warning. The remote monitoring platform greatly facilitates the remote management of the warehouse.

Emission source tracing based on bionic algorithm mobile sensors with artificial olfactory system

AbstractThe leakage of hazardous chemicals and toxic volatile substances in the atmosphere may cause serious consequences such as explosion and poisoning. To identify the unknown leakage locations and gas compositions, a mobile robot system to trace the leak source in the outdoor was investigated. First, two bionic searching algorithms, Zigzag and Silkworm algorithms, were tested with outdoor experiments for locating the leak source. The results showed that the locating errors of these two algorithms were within 0.5 m in 10 by 20 m search space, but the failing ratio of Zigzag and Silkworm algorithm was still high (about 40–50%). Therefore, an improved tracing algorithm combining the Silkworm and Zigzag algorithm, called as zigzag–Silkworm algorithm, was proposed. Compared with Silkworm and Zigzag algorithms, zigzag–Silkworm algorithm had a higher success ratio of 80% in outdoor source tracing tests, and the searching efficiency was enhanced, the efficiency parameter L: L0 has improved from 2.58 for Silkworm and 2.66 for Zigzag to 2.17 for zigzag–Silkworm. Then, in order to identify the composition of the leaked gases during the source tracing, an artificial olfaction system (AOS) based on the gas sensor array and support vector machine was set on the mobile robot. The test results in the source tracing experiments with ammonia and ethanol emissions indicated that the recognition accuracy of emission gases reached to 99% with AOS equipped on the robot. Therefore, the mobile robot system equipped with the zigzag–Silkworm algorithm and the AOS is feasible to trace the leakage source and identify the emission composition in the outdoor leakage event with good performance in efficiency and accuracy although some underlying problems still need to be addressed in future work.