The study of burning behaviors and quantitative risk assessment for 0# diesel oil pool fires
Introduction
A major source of energy in China is 0# diesel oil, which is widely used in modern transportation and industrial production. Pool fires usually occurred during the transportation or storage process of 0# diesel oil. After the pool fires accidents, the high temperature and heat flux were followed produced, which poses a great threat to firefighters and nearby facilities named domino effect. Some serious pool fires accidents were triggered in the past decades by the domino effect (Khakzad et al., 2014; Reniers and Cozzani, 2013). For example, a serious pool fire accident involving 0# diesel occurred in Dalian (Liaoning province, China), which directly resulted from the failure of two storage tanks (Xu et al., 2012). Therefore, it is necessary to analyze the burning behaviors of diesel pool fires and assess the risk of pool fire accident.
The damage effects caused by 0# diesel pool fires are closely associated with the burning behaviors of diesel oil. Over the past few decades, burning behaviors of hydrocarbon pool fires have been studied, including heat feedback (Hamins et al., 1994), mass burning rate (Babrauskas, 1983; Chatris, 2001), flame height (Zukoski, 1984), flame temperature (Mccaffrey, 1979) and thermal radiation (Rew et al., 1997; Steinhaus et al., 2007). An empirical models was provided by Burgess et al. (1961) to predict the burning rate for varied pool diameters (), which has been used by many scholars (Chatris, 2001; Leite and Centeno, 2018). In addition to burning rate, flame height, flame temperature and flame emissivity have been studied by many scholars (Zukoski, 1984; Zhou and Reniers, 2018; Raj and Prabhu, 2018). Zukoski (1984) defined the averaged flame height from the base of a pool to the upper limit where the flame intermittency reaches 0.5. Zhou and Reniers (2018) measured the vertical flame temperature with different diameter thermocouples, and provided a detailed method to determine the emissive power of flame surface by combining the temperature variations in the vertical direction. Raj and Prabhu (2018) found a refined methodology to analyze the spatial flame emissivity variation, and found that emissivity and temperature increased with increasing pool fire diameter, and decreased obviously with increasing flame height. By the above investigations, it seems that the burning behaviors of 0# diesel oil have been well studied. However, some important parameters or models, related to burning behaviors, are still unclear for 0# diesel oil. For example, the value of is approximately 0.034 kg/m2/s in Babrauskas (1983) and 0.057 kg/m2/s in Chatris (2001). Meanwhile, there are many general correlations in the prediction of the flame height and radiation for hydrocarbon pool fires, while which correlations are proper to the 0# diesel oil are not determined nowadays.
Quantitative risk assessment is a common method in the management of industrial parks and the firefighting process (Khakzad, 2014; Reniers and Cozzani, 2013; Cozzani et al., 2006; Mukhim et al., 2017). In the risk assessment, the personal dead probability and the facility failure probability have attracted great attention by many scholars (Reniers and Cozzani, 2013; Cozzani et al., 2006). To personal dead probability, the human vulnerability model was widely used (Lees, 1996; Gledhill and Lines, 1998). Kadri et al. (2013) proposed a method to calculate the personal dead probability under the exposure of overpressure and heat radiation. To the risk of facility failure, some threshold values were selected to decide whether the nearby facility was involved into the fire accident (Cozzani et al., 2006). In addition, a probit model is provided to estimate the failure probability of equipment in domino events triggered by the fire (Landucci et al., 2009). Apart from these models, Bayesian network is often used in the quantitative risk assessment method (Khakzad, 2014). However, some key parameters in the risk calculations are simplified in the above methods. For example, the personal dead probability is closely related to the burning rate. At present, it is difficult to find a proper method to calculate the 0# diesel pool fire risk.
In the present study, 0# diesel pool fires tests for various pan diameters (0.2 m ≤ D ≤ 1 m) and two initial fuel thicknesses (2 cm, 4 cm) were conducted. Some important parameters, including mass burning rate, flame height, heat flux, etc. are discussed and analyzed quantitatively for the corresponding risk assessment. Some correlations including the burning rate, flame height and the emissive power of 0# diesel oil are determined, respectively. Subsequently, a quantitative risk assessment framework combing the experimental results is provided. In the end, 10 special tank fire scenarios were designed. And the personal dead probability and facility failure risk are calculated and analyzed.
Section snippets
Experiments
All experiments were conducted in a large hall where the doors were closed but not sealed, so any wind effect can be ignored. The pool fire experiments were performed using five stainless steel pans with different diameters (0.2 m, 0.4 m, 0.6 m, 0.8 m and 1.0 m), the height of the side wall was 0.1 m. In the experiment, an electronic balance (precision: 0.1 g, maximum: 60 kg, AND) was used to record residual fuel mass in real time, so as to analyze fuel mass variations. A fireproof board was
Methods
In the quantitative risk assessment method for 0# diesel pool fires, the burning behaviors is considered, mainly to calculate the distribution of heat radiation from the flame. As has been known, heat radiation is a main hazard of pool fire accidents, which can result in some disastrous consequences including a large number of casualties and nearby facilities failure (Cozzani et al., 2006). Heat radiation from the flame is key parameter, closely related to the burning rate, flame height and
Mass burning rate and heat release rate
After ignition, it was found that the flame only covered a small part of pan and then the burning area gradually increase to cover the pan surface totally. Along with the expansion of burning area, the flame height also gradually increased, and soon became stable. Black smoke around the flame was clearly observed. At the end of the burning cycle, the flame height decreased rapidly and then gradually disappeared as the fuel was depleted. Photographs of the burning stages at some special times
Conclusions
The burning behaviors of 0# diesel oil pool fires were investigated by an experimental method. In the experiments, key parameters, including mass burning rate, heat release rate, and flame height, were measured and analyzed in detail. Moreover, a quantitative risk assessment framework for 0# diesel pool fire is proposed combined the above experimental results. In the framework, personal dead probability and facility failure risk are analyzed and calculated. Such knowledge will be essential to
Author contribution statement
Jie Yuan designed the study and wrote the paper. Jinlong Zhao and Jie Yuan, Wei Wang performed the experiments. Jinlong Zhao and Jie Yuan processed the experimental data. Jinlong Zhao, Rui Yang, Changkun Chen and Ming Fu reviewed the manuscript. All authors read and approved the manuscript.
Declaration of competing interest
The authors declare there are no conflicts of interest regarding the publication of this paper.
Acknowledgements
This study was sponsored by the National Key R&D Program of China (No. 2018YFC0809900), the Fundamental Research Funds for the Central Universities (No. 2020QN05 and No. 2021JCCXAQ01) and the National Natural Science Foundation of China (No. 51906253).
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