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This paper presents an experimental investigation on mass burning rate and flame geometry characteristics of crude oil boilover fire under cross air flows. Three circular steel trays with different diameters, filled with crude oil with different initial layer thickness were used in this experiment. The cross air flow speed ranges from 0 to 1.5 m/s. The mass burning rates, flame length and tilt angle in the steady stage and boilover stage were recorded. The results show that the response of steady mass burning rate to cross air flow speed showed a non-monotonic trend, which firstly decreased and then increased with the critical cross air flow speed of 1.0 m/s. The boilover mass burning rate also shows a similar non-monotonic response to the cross air flow speed, with a critical value of 0.5 m/s. Such change trends are discussed based on the physical change of the dominant controlling mechanism in the heat feedback. An improved Thomas model was developed for the correlation of flame length in boilover stage to account for the initial fuel layer thickness effects. The flame tilt angles in steady stage and boilover stage are correlated well based on the tangent value of the angle.

Crude oil boilover fire was experimentally studied in an open fire test space. Three circular steel trays, with diameters of 0.1 m, 0.15 m and 0.2 m, filled with crude oil were used in the experiment. Three important measurements, namely, mass burning rate, flame height and fuel temperature distributions, were collected and recorded during the entire combustion process. The results show that the combustion process can be divided into four typical stages: the growth stage, quasi-steady stage, boilover stage and decay stage. It is observed that the mass burning rate and the flame height in the boilover stage are considerably higher than that in the quasi-steady stage. In the quasi-steady stage, the initial fuel layer thickness has a limited influence on the mass burning rate and the flame height, whereas in the boilover stage, the influence is substantial because of the boilover effect. In both stages, the mass burning rate and the flame height increase with increasing pool diameters. The two boilover characteristic parameters, boilover onset time and boilover intensity, both increase with the initial fuel layer thickness and decrease with the pool diameter. Based on the ratio of initial fuel layer thickness to the pool diameter, prediction models for boilover onset time and boilover intensity are developed.

Spontaneous combustion of the sulfide mineral is one of the major challenge during the sulfide mineral storage and transportation. To evaluate the pyrophoric risk of the sulfide mineral, the thermo-gravimetry and differential scanning calorimetry (TG-DSC) technique were employed to evaluate the thermal behavior of the sulfide concentrate sample. The samples were heated from ambient temperature to 1000 °C at four heating rates. The thermodynamic parameters were obtained from the experimental data. Based on Semenov model, the self-accelerating decomposition oxidation temperature (SADT) and temperature of no return ( T NR ) were calculated. Assuming that the sulfide stockpile is under quasi adiabatic condition, the auto ignition delay time (AIDT) of the sulfide stockpile was predicted. Results indicate that the oxidation of sulfide concentrate sample under different heating rates undergoes a similar process: an initial physical absorption stage, a subsequent chemical absorption stage and a final reaction stage. The thermal behavior of the sulfide mineral at different heating rates indicates that the more rapid the heating rate, the higher the onset and peak temperature. As the heating rate increases, the AIDT decreases from approximately 20 to 12 days under a given set of conditions. The information obtained in the present study is useful for mitigating hazards due to the spontaneous combustion of a large pile of sulfide mineral in storage.

The energy model of CNC worm wheel grinding machine tools is an important basis of the analysis of energy consumption characteristics and energy optimization. In this paper, the multi-source energy flows are divided into four parts that are main driving system, feeding system, grinding wheel dressing system and auxiliary system for the structural features of CNC worm wheel grinding machine tools. The mathematical model of multi-source energy flows is established based on the analysis of energy flow balance equation of the four parts. The energy flow models play an important supporting role in the evaluation of energy utilization effect and factors affecting energy consumption, prediction of energy consumption and optimization of energy saving.