Search Results (97)

Anaerobic digestion of sugarcane vinasse is integral to enhancing ethanol distilleries’ environmental and energy performance by converting organic waste into biogas; however, the flammable and toxic nature of biogas has led to significant safety concerns, particularly in anaerobic bioreactors where biogas is produced and stored. This study provides a comparative risk assessment of different anaerobic reactor configurations—a covered lagoon biodigester (CLB), a continuous stirred-tank reactor (CSTR), an upflow anaerobic sludge blanket reactor (UASB), and an anaerobic structured-bed reactor (AnSTBR)—processing vinasse, focusing on fire, explosion, and hydrogen sulfide (H₂S) toxicity hazards. Jet fire scenarios posed the most severe threat, with fatal outcomes extending up to 66 m, while the fireball scenario exhibited no lethal range. The risks to human life from explosions were minimal (1.2%). H₂S toxicity was identified as the most critical consequence, with particularly severe impacts in CLB systems, where the hazardous zone was up to 20 times larger than in AnSTBR. Therefore, the design of anaerobic bioreactors for vinasse treatment must primarily address the risks associated with H₂S-rich biogas, as reactor configuration plays a key role in mitigating or amplifying these hazards—high-rate systems such as AnSTBR and UASB demonstrating safer profiles due to their compact design and lower gas storage volumes. Full article

With the rapid expansion of electric vehicles, the risk of battery fires has become a critical safety concern. Conventional suppression methods, such as submerging battery packs in large water tanks, are inefficient due to long response times and potential secondary hazards. This study introduces a polymer-based fire suppression tube system that automatically activates under specific conditions. The system utilizes energy from a C4 explosion to rupture the tube, rapidly releasing the extinguishing agents stored inside. Explicit dynamics simulations in ANSYS Workbench 2024 R2 were conducted by varying tube thickness from 0.5 mm to 2.0 mm to evaluate the structural response of adjacent components. Three indices were examined: total deformation, deformation of the adjacent plate, and deformation of the tube itself. The results showed that thinner tubes (0.5 mm) allowed for greater propagation of blast energy, increasing the risk of damage, whereas thicker tubes (≥1.5 mm) effectively confined the explosive energy and reduced shock transmission. These findings confirm that tube thickness is a key parameter governing blast-induced deformation, with 1.5 mm identified as the threshold for minimizing structural damage. This study provides practical design guidelines for polymer-based automatic suppression systems, contributing to safer fire protection solutions for electric vehicles and related industrial applications. Full article

The rising cost of traditional energy sources is forcing us to seek alternatives that enable energy self-sufficiency. At the Madrid Zoo Aquarium (Spain), the production of biomethane through the anaerobic digestion of organic waste is being considered, improving environmental management and achieving a competitive advantage in the energy management process. This opportunity also carries with it the possibility of explosions, fires or polluting environments, which requires the establishment of preventive measures to minimize these risks. To respond to this type of contingency, this study develops both empirical equation and charts that allow the establishment of dangerous distances that must be considered due to the presence of flammable gases escaping into the atmosphere and the duration of the danger, taking into account the influence of environmental conditions and dilution. Different risk situations are considered, both during the operation of the facility and during the cleaning and maintenance of tanks and equipment, as well as in the management of waste generated at the end of treatment. Full article

Fossil fuel-based power production faces challenges, particularly greenhouse gas emissions, that contribute to global warming. This paper explores retrofitting an existing 207.8 MW coal-fired steam power unit with a Concentrated Solar Power (CSP) tower system and Thermal Energy Storage (TES) systems to create a hybrid solar–coal power plant. The concept integrates a solar component and a two-tank TES system into the existing steam Rankine cycle. Thermodynamic modeling and balance calculations were performed using Ebsilon Professional software (version 16) to analyze the design. Three injection points for feedwater preheating were analyzed, with flow rates that varied from 10 to 100 kg/s. Thermodynamic simulations show that solar contributions of 16.0 MW (Variant 1), 27.6 MW (Variant 2), and 37.6 MW (Variant 3) increase net electricity output to 213.5 MW, 216.8 MW, and 219.3 MW, respectively. The corresponding thermal efficiencies rise from 42.6% to 43.8%, while the hybrid system’s total efficiency improves up to 29.6%. These results demonstrate that controlled feedwater diversion and solar integration can enhance performance, reduce coal dependency, and lower CO₂ emissions without compromising operational stability. Full article

To address the difficulty frontline commanders face in accurately perceiving fireground risks during the early stages of oil storage tank fires, in this study, we propose a method that integrates complex network theory with a multi-source information fusion approach based on cloud models and Dempster-Shafer (D-S) evidence theory for situational analysis and dynamic perception. Initially, the internal evolution of accident scenarios within individual tanks is modeled as a single-layer network, while scenario propagation between tanks is represented through inter-layer connections, forming a multi-layer complex network for the storage area. The importance of each node is evaluated to assess the risk level of scenario nodes, enabling preliminary situational awareness, with limited reconnaissance information. Subsequently, the cloud model’s capability to handle fuzziness is combined with D-S theory’s strength in fusing multi-source data. Multi-source heterogeneous information is integrated to obtain the confidence levels of key nodes across low, medium, and high-risk categories. Based on these results, high-risk scenarios in oil storage tank emergency response are dynamically adjusted, enabling the updating and prediction of accident evolution. Finally, the proposed method is validated using the 2015 Gulei PX plant explosion case study. The results demonstrate that the approach effectively identifies high-risk scenarios, enhances dynamic situational perception, and is generally consistent with actual accident progression, thereby improving emergency response capability. Full article

Hydrogen energy is considered a crucial clean energy carrier for replacing fossil fuels in the future. Liquid hydrogen (LH₂), with its economic advantages and high purity, is central to the development of future hydrogen refueling stations (HRSs). However, leakage poses significant fire and explosion risks, challenging its safe industrial use. In this study, a numerical model of LH₂ leakage at an HRS in Chongqing was established using Computational Fluid Dynamics (CFD) software. The diffusion law of a flammable gas cloud (FGC) was examined under the synergistic effect of the leakage direction, rate, and wind speed of an LH₂ storage tank in an HRS. The phase transition of LH₂ presents dual risks of combustion and frostbite owing to the spatial overlap between low-temperature areas and FGCs. The findings revealed that the equivalent stoichiometric gas cloud volume (Q9) reached 685 m³ in the case of crosswind leakage, with the superimposed effect of reflected waves from the LH₂ transport vehicle resulting in a peak explosion overpressure of 0.61 bar. The low-temperature hazard area and the FGC (with a concentration of 30–75%) show significant spatial overlap. These research outcomes offer crucial theoretical underpinning for enhancing equipment layout optimization and safety protection strategies at HRSs. Full article

Mathematical modeling and computer visualization of hazardous zones of toxic substance cloud spread that occur during different accidents at industrial enterprises located near residential areas are in high demand to support the operational planning of evacuation measures and accident response. The possible chain-like nature of fires and explosions of containers with toxic substances inside increases the importance of predicting changes in hazardous zone parameters in real time. The objective of this study is to develop algorithms for the development of a mathematical model of a hazardous zone during an explosion and fire at an enterprise. The subject of this study is a software tool created for the visualization of hazardous substance emission zones in real time, superimposed onto a development map to determine potential damage to human health and for the operational planning of evacuation measures. The proposed model takes into account variables such as the air temperature, wind speed and direction, the mass of the substance at each explosion and fire site, etc. C# and Visual Studio 2022 languages and an SQL database were used to create a software tool for visualizing the hazardous area. The testing of the calculation model and software used for the visualization of the hazardous zones of toxic substance cloud spread are presented on the basis of explosion cases involving a railway tank containing ammonia and the combustion of polyvinyl chloride at a chemical industry enterprise. The results confirmed the operability of the software and the prospects of its use in regard to the mitigation of the consequences of human-made accidents. Full article

To enhance fire safety in converter stations, this study focuses on detecting abnormal data and potential faults in fire protection Internet of Things (IoT) devices, which are networked sensors monitoring parameters such as temperature, smoke, and water tank levels. A data quality evaluation model is proposed, covering both validity and timeliness. For validity assessment, a transformer-based time series reconstruction method is used, and anomaly thresholds are determined using the peaks over threshold (POT) approach from extreme value theory. The experimental results show that this method identifies anomalies in fire telemetry data more accurately than traditional models. Based on the objective evaluation method and clustering, an interpretable health assessment model is developed. Compared with conventional distance-based approaches, the proposed method better captures differences between features and more effectively evaluates the reliability of fire protection systems. This work contributes to improving early fire risk detection and building more reliable fire monitoring and emergency response systems. Full article

This paper presents a review of explosion mitigation techniques for road tunnels, with a focus on scenarios involving high-pressure hydrogen tank rupture under fire conditions. Both passive and active strategies are considered—including structural configurations (e.g., tunnel branching, vent openings, right-angle bends) and protective systems (e.g., drop-down perforated plates, high-performance fibre-reinforced cementitious composite (HPFRCC) panels)—to reduce blast impact on tunnel occupants and structures. The review highlights that while measures such as blast walls or energy-absorbing barriers can significantly attenuate blast pressures, an integrated approach addressing both blast load reduction and structural resilience is essential. This paper outlines how coupled computational fluid dynamics–finite element method (CFD–FEM) simulations can evaluate these mitigation methods, and we discuss design considerations (e.g., optimising barrier placement and tunnel geometry) for enhanced safety. The findings provide guidance for designing safer hydrogen vehicle tunnels, and they identify gaps for future research, including the need for experimental validation of combined CFD–FEM models in hydrogen fire–explosion scenarios. Full article

Zero-liquid discharge (ZLD) of desulfurization wastewater from coal-fired power plants is a critical challenge in the thermal power industry. Flash evaporation technology provides an efficient method for wastewater concentration and the recovery of high-quality freshwater resources. In this study, numerical simulations of the high-temperature and high-pressure spray flash evaporation process within a flash tank were conducted using the Discrete Phase Model (DPM) and a self-developed heat and mass transfer model for superheated droplets under depressurization conditions. The effects of feedwater temperature, pressure, nozzle spray angle, and mass flow rate on spray flash evaporation characteristics were systematically analyzed. Key findings reveal that (1) feedwater temperature is the dominant factor, with the vaporization rate significantly increasing from 19.78% to 55.88% as temperature rises from 240 °C to 360 °C; (2) higher pressure reduces equilibrium time (flash evaporation is complete within 6 ms) but shows negligible impact on final vaporization efficiency (stabilized at 33.93%); (3) increasing the spray angle provides limited improvement to water recovery efficiency (<1%); (4) an optimal mass flow rate exists (0.2 t/h), achieving a peak vaporization rate of 42.6% due to balanced evaporation space utilization. This work provides valuable insights for industrial applications in desulfurization wastewater treatment. Full article

With the introduction of the “dual carbon” strategy, public attention to green energy has surged, leading to a notable increase in the demand for natural gas. Consequently, the storage and transportation of liquefied natural gas (LNG) have emerged as critical aspects to ensure its safe and cost-effective utilization. For onshore LNG storage, LNG storage tanks play a pivotal role. However, in extreme scenarios such as fires, these tanks may be exposed to radiant heat, which not only jeopardizes their structural integrity but could also result in LNG leaks, triggering severe safety incidents and environmental disasters. Against this backdrop, this study delves into the evaporation characteristics of large-scale LNG storage tanks under fire radiation conditions. Given the unique properties of LNG and the similarity between the bubble-point lines and heat exchange curves of nitrogen and LNG, liquid nitrogen is employed as a substitute for LNG in experimental investigations to observe evaporation behaviors. Furthermore, the FLUENT 2022R1 software is utilized to conduct numerical simulations on a 160,000-cubic-meter LNG storage tank, aiming to model the intricate process of internal evaporation and the impact of environmental factors. The findings of this research aim to furnish a scientific basis for enhancing the storage safety of large-scale LNG storage tanks. Full article

Nitrous oxide is a highly suitable oxidizer for hybrid rockets due to its self-pressurizing properties, moderate cost, and high accessibility. However, its vapor pressure and density are highly dependent on ambient temperature, requiring careful consideration of temperature variations in real applications. To mitigate this issue, an oxidizer called Nytrox was produced by adding a small fraction of oxygen to bulk nitrous oxide. This modification enables the hybrid rocket propulsion system to maintain a nearly constant average thrust and total impulse across a wide range of ambient temperatures. A series of 7 s hot-fire tests of a small Nytrox/polypropylene hybrid rocket engine operating at ~60 barA of running tank pressure demonstrated a consistent average thrust of 45.3 ± 0.7 kgf and a total impulse of 307.6 ± 3.9 kgf·s within a N₂O temperature range of 5.9–22.6 °C, compared to highly varying values of the N₂O/polypropylene one within a N₂O temperature range of 10.8–29.8 °C. Furthermore, the specific impulse of the Nytrox hybrid rocket engine increases mildly with decreasing temperature because of the increasing amount of added oxygen that benefits the combustion for generating the thrust. Full article

This study aims to evaluate the effectiveness of helicopters in fighting forest fires in Türkiye. The increasing frequency and severity of forest fires, especially with climate change, require more effective aerial response methods. Helicopters play a critical role due to their operational advantages, such as maneuverability, rapid access, and water-carrying capacity. In this study, the types of helicopters used in Türkiye are analyzed, and their operational efficiency is evaluated using Data Envelopment Analysis (DEA). The results reveal that certain models show high efficiency, but some helicopters have room for improvement in terms of fuel consumption and technical performance. A balanced use of both Bambi Bucket and internal water tank systems in fighting forest fires in Türkiye and investing in domestic production is recommended. Full article

Due to the high saturated vapor pressure of low-boiling-point flammable liquids, it is difficult to make fire extinguishers for storage tanks containing them. Air foam extinguishing technology has been recommended by several standards. However, the effectiveness of air foam against low-boiling-point flammable liquid is still limited due to a lack of experimental data. To validate the reliability of air foam, fire-extinguishing measures for three low-boiling-point flammable liquids including propylene oxide, n-pentane, and condensate oil were carried out for the first time in this work. The results show that air foam fails the fire extinguishment of the studied liquids even at higher supply intensities. To address the challenge of fire extinguishment in storage tanks containing low-boiling-point flammable liquids, a novel method using heptafluoropropane (HFC227ea) phase change foaming to substitute air was proposed in this work. The experimental system of HFC227ea foam fire extinguishment was constructed. In addition, two low-boiling-point flammable liquids propylene oxide and n-pentane were selected as the research subjects, the fire extinguishment measures were conducted. The results show that the proposed method can realize rapid and effective extinguishment of flames for the studied liquids. Full article

Ammonia is a gas with high toxicity, which is produced in large amounts as raw materials for nitrogen-based fertilizer. Fertilizer plants in Indonesia are sometimes located not far from residential areas, requiring risk assessment for the loss of containment (LoC) event of ammonia. Many studies have modeled ammonia release using ALOHA software but stopped the calculation at the consequence modeling and did not evaluate the risk quantitatively. In this study, a quantitative risk assessment (QRA) was conducted for the LoC of ammonia from the storage tank at PT X, a fertilizer industry in Indonesia, using RISKCURVES software. The scenario and their frequency were chosen based on the Netherlands QRA guidelines. The simulation shows five types of phenomena happening, with toxic dispersion being the most dangerous. Atmospheric conditions influence the toxic dispersion but barely affect the fire and explosion phenomena. Despite the severity of the toxic dispersion, the individual risk calculation shows that the risk in the fertilizer plant area is still acceptable based on the standard of UK HSE. Full article