Journal of Loss Prevention in The Process Industries最新文献

This work outlines the experimental conditions and tests results for a cylindrical carrier submitted to a large (>20 m²) and powerful (>40 MW) pool fire to assess its compliance with safety regulations for transporting hazardous materials. Data from thermocouples placed around the carrier, above the pool fire, in the fire plume, and from plate thermocouples at the edge of the pool fire are provided. The temperature criteria of 800 °C were met both close (10 cm) and away (50 cm) from the tank.

Furthermore, a validation analysis was performed using Fire Dynamics Simulator code to assess its predictive capabilities for simulating large-scale pool fires with engulfed tanks. Numerical results demonstrated good agreement with the experimental data, highlighting its potential to assist in the dimensioning or design of such large-scale tests.

Hazardous chemical spill accidents are difficult to detect by the potentially threatened public in the infancy and early stages of development of the disasters. Accurate and timely emergency warnings will help the affected public understand disaster information and assist in risk perception. First, we propose an emergency communication information field (ECIF) model to estimate the effectiveness of emergency communication based on information field theory, taking into account factors such as warning sources, communication channels, information content, and the risk area population's ability to interpret warnings. Second, we calculate the field strength and information potential energy of the warning based on the field theory model to evaluate the coverage rate and the amount of information obtained from the warning by the risk area population to estimate whether people can receive warning information. Finally, we apply the model to a scenario of liquid chlorine spill and illustrate the applicability of our method by taking television (TV), fixed loudspeakers (hereinafter referred to as Loudspeaker), short-message service (SMS), and WeChat groups as examples. The results show that the effectiveness of emergency communication varies significantly with the age of people. When TV is the only channel for emergency communication, the elderly have a higher information receipt capacity for warnings than young-middle-aged people. Another interesting finding is that increasing emergency communication channels may not be an effective measure to improve warning efficiency due to different characteristics of the population. These findings are expected to provide new insights for emergency management agencies in the formulation and optimization of communication strategies.

To prevent the explosion of sucrose dust, the ability of carbonate powders as a sucrose dust explosion inhibitor is systematically analyzed and compared. The explosion inhibition effect of carbonate powders on sucrose dust is investigated by means of minimum ignition energy (MIE) and 20 L sphere explosion experiments. The results indicate that as the amount of carbonate powder added increased, sucrose dust explosion can be completely inhibited. Compared with CaCO₃, KHCO₃, and NH₄HCO₃, the inhibitory ability of NaHCO₃ is 25.00%, 40.00%, and 57.14% better for MIE and 25.00%, 33.33%, and 50% better for explosion properties. The kinetic model of thermal decomposition of sucrose dust before and after NaHCO₃ intervention was comparatively analyzed and validated using Coats-Redfern (C–R) and Kissinger - Akahira - Sunose (KAS) methods. The kinetic modeling of the thermal decomposition of sucrose dust before and after the addition of NaHCO₃ was found to follow the chemical reaction mechanism (F4 model). Further fitting analysis demonstrates that after adding NaHCO₃ inhibitor, the apparent activation energy of sucrose dust is greatly increased, further confirming that carbonate powders can greatly inhibit sucrose dust explosion on thermodynamic terms. Finally, based on the characterization result, the inhibitory mechanisms of carbonates on sucrose dust explosion are proposed and two reasons explaining why NaHCO₃ has better inhibitory ability than CaCO₃, KHCO₃, and NH₄HCO₃ are summarized. One is that the decomposition of NaHCO₃ is a highly heat-absorbing process during which part of the heat produced by the combustion of sucrose dust is absorbed. The other is that NaHCO₃ and its product have small particle sizes but large specific surface areas, consequently higher unit heat absorption capacity and better dispersivity.

Scaling hydrogen as a key clean energy carrier necessitates a comprehensive understanding of the safety aspects of hydrogen including liquid hydrogen (LH₂). Hence, this study presents a detailed computational fluid mechanics analysis to explore accidental LH₂ leakage and dispersion in a hydrogen refuelling station under varied conditions which is essential to prevent fire and explosion. The correlated impact of influential parameters including wind direction, wind velocity, leak direction, and leak rate were analysed. The study shows that hydrogen dispersion is significantly impacted by the combined effect of wind direction and surrounding structures. Additionally, the leak rate and leak direction have a significant effect on the development of the flammable cloud volume (FCV), which is critical for estimating the explosion hazards. Increasing wind velocity from 2 to 4 m/s at a constant leak rate of 0.06 kg/s results in an 82% reduction in FCV. The minimum FCV occurs when leak and wind directions oppose at 4 m/s. The most critical situation concerning FCV arises when the leak and wind directions are perpendicular, with a leak rate of 0.06 kg/s and a wind velocity of 2 m/s. These findings can aid in the development of optimised sensing and monitoring systems and operational strategies to reduce the risk of catastrophic fire and explosion consequences.

A large number of flammable hazardous materials are stored in chemical tank farms, where fire-induced domino accidents can be easily triggered. In this study, a novel real-time fire situation awareness (FSA) approach based on UAV is proposed to capture spatio-temporal evolution characteristics and predict development trends of fire accidents. Firstly, fire images are acquired by UAV, and the key parameters of fire are extracted in real time based on YOLOv8 network. Then, the thermal radiation and impact on surrounding equipment are predicted by combining LSTM network, solid flame model and improved probit model. The proposed method is verified by small-scale tank fire experiments, which demonstrate its superiority in terms of physical consistency and prediction accuracy. The results show that the mean absolute percentage error (MAPE) of fire parameter extraction is not higher than 5.43%, the MAPE of thermal radiation prediction is not higher than 25%, and the dynamic time to failure ($dttf$) for the model tank at different location is predicted. This work has the potential to provide a novel solution for real-time assessment of fire size and trend prediction to support firefighting, emergency rescue and decision making in fire accident scenarios.

Experiments on the effects of ignition position and hydrogen ratio (χ) on the explosions of CH₄/H₂/air mixtures were experimentally investigated in a vented cylindrical vessel. Relevant experiments were conducted utilizing ignition sources situated at the rear (rear ignition), the center of the vessel (central ignition), or near the vent (front ignition) with χ varying from 0 to 1.0. Two types of cellular structures on the flame surface, owing to the diffusional-thermal instability and acoustically enhanced combustion, respectively, were observed, and the latter resulted in acoustic oscillations of the overpressure within the vessel and a unique overpressure peak $p_2$ with amplitude sensitive to both ignition position and χ. The effects of ignition position and χ on the build-up of the internal pressure were not significant when χ ≤ 0.15. The maximum explosion overpressure in the vessel ($p_{\max }$) under the explosions of rear and central ignitions (RI and CI) increased monotonically as χ was increased from 0.3 to 1.0, but a nonmonotonic trend was found in the explosions of front ignition (FI). CI could be regarded as the worst-case scenario when 0.45≤χ ≤ 1.0 except for χ = 0.7, because FI resulted in the highest $p_{\max }$ at χ = 0.7. A pressure peak outside the vent ($p_{ext}$) caused by the combustion expansion of the combustible cloud could be distinguished when χ ≥ 0.45 in the explosions of RI and CI. The amplitude of $p_{ext}$ increased with an increase in χ. Rear ignition always led to the highest $p_{ext}$ when χ > 0.6.

We present experiments of two dimensional high-Reynolds ($Re>2400$) turbulent gravity current advancing down on slope $(\theta =5°)$ generated by continuous buoyancy flux. The current research is focused on understanding the flow mixing mechanism and consequently the rate of volume growth for the development of mathematical model to calculate the volume of the current. The gravity currents were obtained pumping saline solution continuously into a channel filled with fresh water. Images of the flow were taken with a ratio of 4 frames per second (fps). The gravity current buoyancy distribution was obtained by using light attenuation technique to calculate the cross-channel average of the density. It was found that the proportional parameter $\lambda$ in $U_F=\lambda {\left(Q_0{g}_0^{\prime }\right)}^{1/3}$ is $\lambda =1.23/F{r}_0^{1/12}$. The head reaches a dynamic equilibrium for $F{r}_F\approx 0.95$, where $F{r}_H=U_F/\sqrt{g_F^{\prime }{h}_F}$. Three mixing zones were observed; near the source, tail and head. The ambient fluid volume fluxes entraining the current into this three zones were modelled in terms of entrainment coefficients ${\varepsilon }_j$, ${\varepsilon }_T$, ${\varepsilon }_H$, respectively. A model of the rate of growth of the volume of the current was developed, it is written as