We attempted to prevent the thermal risk of a runaway reaction of polymerization in a batch reactor and to realize online monitoring and emergency inhibition of the thermal runaway behavior. Styrene thermal initiation of bulk polymerization was studied. A full-size model of the styrene polymerization reactor was constructed by referring to the reactor model of the Mettler Toledo automatic calorimeter, which was combined with the kinetic and thermodynamic models of styrene polymerization. The DIV thermal runaway critical criterion based on chaos divergence theory was used to judge the thermal runaway reaction. The critical point of the runaway reaction was determined and used to inhibit the thermal runaway of styrene polymerization by injecting cooling diluents at the liquid surface. The influence of injection rate (vc=0.5、0.8、1m/s), injection position (in-1、in-2、in-3), and amount of cooling diluents (no add、50%、70%、100%) injected on the thermal runaway inhibition of the reaction was investigated and elucidated. The results indicated that a better inhibiting effect can be obtained by injecting the inhibitors at higher rates near the edge of the paddle blade. Moreover, appropriately increasing the injection amount of the inhibitors can achieve better inhibition of the runaway reaction.

1-Ethyl-2, 3-dimethylimidazolium nitrate [C2mmim][NO3] is a typical solvent for industrial applications. Under inappropriate temperatures, [C2mmim][NO3] may present a flammability hazard due to thermal decomposition. This study investigated the thermal stability and flammability of [C2mmim][NO3] via simultaneous thermogravimetric analyzer, homemade combustion test device (CTD) with high speed camera, and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The thermal decomposition of [C2mmim][NO3] was divided into two parts based upon the dynamic experiments, and the maximum operating temperature was determined to comprehensively estimate the thermal stability of [C2mmim][NO3]. CTD experiments indicated that [C2mmim][NO3] could produce intense combustion when heated. Further TG-FTIR experiments confirmed that [C2mmim][NO3] decomposed to produce a large number of flammable gases, such as ethylene, which might be the reason that [C2mmim][NO3] has prominent flammability.

This work presents a study of the separation and recovery of metal elements, through a multi-step protocol based on solvent extraction, stripping and chemical precipitation processes. The waste leachate was produced during the treatment of the mixed solid waste from the decommissioning of a coal-fired power plant. The organophosphorus acid, di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated as organic extracting agent during the solvent extraction (Step 1). A factorial design with three levels for the organic phase/aqueous phase ratio (O/W), DEHPA concentration and contact time were carried out and a prediction model obtained using a neural-fuzzy approach. Optimized extraction values for Ti (93.4 %), (V) 94.6 % and (Zn) 89.8 % were obtained using 60 min of contact time, a DEHPA concentration of 0.5 M and O/W ratio of 4. Stripping tests were performed using HCl, H2SO4, NaOH and KOH as stripping agents. The stripping step (step 2) showed optimum results (82% of Zn and 31% of V) using 1 M H2SO4 solution as stripping agent. A selective precipitation step (step 3) allowed the final separation of metals in aqueous solutions produced in Step 1 and 2. The results showed that an effective separation of Mn and Ni could be carried out at pH 9, while the best separation results for the solution obtained during the stripping step, which contains V and Ti, was obtained at pH 12.

Distillation column is a fundamental device for the production of the semiconductor polysilicon. Therefore, investigating corrosion leakage protection of the distillation column is of great significance because of the undetectable yet very significant consequences of corrosion leakage to the column. In this work, corrosion investigation of a polycrystalline silicon rectification tower is presented. The composition and crack morphology of the distillation column (316 L austenitic stainless steel) were detected and analysed using component and hardness analysers. The effects of pH and temperature on the corrosion rate were studied by conducting electrochemical experiments. According to the macroscopic test results, the surface of the tower was covered with a large number of pits and cracks of different depths. Furthermore, based on the metallographic analysis, SEM analysis, and energy spectrum analysis results, it was determined that the crack morphology was mostly intergranular and transgranular. Combined with the test data and process environment, it has been determined that the main forms of corrosion for rectification towers are pitting corrosion and stress corrosion caused by chloride ions. According to the results of electrochemical experiments, the corrosion rate of 316 L stainless steel is negatively correlated with pH value for a pH range of 4 to 6 at constant temperatures. However, the corrosion rate is positively correlated with temperature for the range of 60 °C to 90 °C at constant pH values. From the analysis of the corrosion morphology, the corrosion failure mode of 316 L stainless steel is largely attributed to pitting corrosion when the column is operated at low temperatures (60 °C and 70 °C). However, at high temperatures (90 °C), a transformation from pitting corrosion to stress corrosion occurs along the crystalline form. To ensure the stable operation of the polysilicon rectification tower, this paper proposes corrosion protection measures based on the results of the analysis as described.

Jet fires and their consequences are one of the significant factors responsible for catastrophic events in industrial process units. In this research, various types of turbulence models were investigated to simulate a vertical propane jet fire using computational fluid dynamics (CFD). CFD was applied to evaluate the following turbulence models of k-ε, SST, BSL, BSL RS and the Realizable k-epsilon (RNG k-ε), the Eddy Dissipation Concept (EDC) for combustion, and the Monte Carlo model for radiation. All the above-mentioned turbulence models are used for a temperature range of 1500 to 1700 K. The results showed that the SST turbulence model is the best option, with average error of 4.7% for a jet fire simulation, with a lower computational time. The simulation of the jet fire shape at surface temperature of 800 K was also compared with the experimental data obtained under the same conditions. By taking into account the time parameter in the simulation, the predicted ratio of flame length and equivalent flame diameter results are in good agreement with the experimental jet fire data.

Many types of explosions often occur in industrial settings, and research is being conducted to identify the causes and establish preventive measures. The aim of this study is to investigate slag yards, where metal residues are cooled in the steel industry, often causing steam explosions. The cause of accidents and explosion simulation analyses were used to investigate the sources of steam explosions in a slag yard. The explosion intensity of 4 kg of TNT was measured for the purpose of predicting the intensity of a steam explosion. This was compared with a simulation of explosion damage that occurred in 2017. These results could not be produced from small-scale experiments, and they indicate that damage resulting from actual explosions poses a potential risk to pipes that cannot be directly observed. We conclude that this damage can lead to a domino accident, and this study provides results for estimating the possibility of future damage.

Organic ultraviolet absorbents (UVAs) are widely found in the environment. However, little is known about UVA distributions in street dust and the risks they pose to human health. We determined the concentrations of 12 UVAs in street dust from cultural, residential, traffic, and industrial areas in Hefei, China. 4-Methylbenzylidene camphor was not detected in the street dust samples. The total concentration range of the 11 other UVAs (Σ11UVAs) in the street dust samples was 6.42–94.2 ng/g. Octocrylene was the dominant UVA, contributing 53.8% of the Σ11UVA concentrations. The UVA concentrations were higher in dust from the industrial area than in dust from cultural, residential, and traffic areas. Source analysis was performed, and industrial activities and the use of cosmetics and personal care products were found to be the main sources of UVAs in street dust. The health risks posed to humans exposed to UVAs in street dust in Hefei were generally low. More research is required to improve our understanding of the health risks posed to humans exposed to UVAs through other pathways.

Gas explosion is one of the most deadly hazards in underground coal mining. Risk assessment has played an effective role in avoiding gas explosions and revising coal mine regulations. However, the traditional methods are deficient in quantitative evaluation, dynamic control and dealing with uncertainty. In this paper, a method of quantitative assessment the risk of gas explosion in underground coal mine using Bayesian network was proposed. A fuzzy analytic hierarchy process (FAHP) method based on subjective and objective information of experts was developed in the process of fuzzification. Through the Bayesian inference, the probability of occurrence of potential risk events and the probability distribution of risk factors can be calculated in real time according to on prior knowledge and evidence updating. Meanwhile, the most likely potential causes of accidents can be determined. A sensitivity analysis technique was utilized to investigate the contribution rate of each risk factor to a risk event, so as to determine the most critical risk factor. Taking Babao Coal Mine in China as the case, this study conducted a gas explosion risk assessment. The results show that the mothed of fuzzy AHP and Bayesian Network is feasible and applicable. It can be used as a decision-making tool to prevent coal mine gas explosions and provide decision makers with a technical guide for managing the coal mine gas explosion risk.

Fire is a main threat to property and human safety in materials storage of process industry plants as well as other industrial sectors, and risk management of materials storage fires is challenging due to potential accident causes and various safety measures. Complex accident causes, severe consequences, and effective safety measures have been the main concerns of industrial companies and researchers. However, for storage fires, a generic risk management model is absent. Bow-tie is an effective method to reveal causal relationships of accident causes, safety barriers, and possible accident consequences. In this study, based on bow-tie analysis, a generic framework for quantitative risk management of storage fires is established via analysis of previous storage fires. Pertinent safety measures are presented, allocation and efficacy of these safety measures to reduce storage fires risk is investigated. Finally, the methodology and proposed generic framework is applied to a major storage fire accident for a case study, the probabilities of fire accident and consequences are reduced significantly, which shows the efficacy and applicability of the proposed approach. The generic framework established in the present study can be tailored to various storage fire accidents with limited manipulation; and also, allocation and implementation of pertinent safety measures can reduce storage fires risk significantly.

Fe2+ is essential for the improvement of biogas production and the growth of anaerobic microorganisms; however, it is often excessively added to anaerobic digesters, leading to the inhibition of biogas production. In this study, the dosing frequency of Fe2+ for the mesophilic and thermophilic biogas fermentation of high-solid swine manure was optimized. The most significant enhancing effect (13.44%-33.22%) induced by Fe2+ addition was observed with dosing frequency of 400 mg/L for every 5 d, and the maximum efficiency for unit concentration of Fe2+ occurred when the dosing frequency was 400 mg/L for every 15 d. Maximum biogas production was obtained in the group with dosing frequency of 400 mg/L for every 5 d, and biogas production potential was 465.24 mL/(g volatile solid (VS)) based on modified Gompertz predicted model with a maximum rate of 16.72 mL/(gVS·d), which was higher than that of the control group (6.78 mL/(gVS·d)). In addition, Fe2+ dosing displayed a stimulatory effect on SCOD removal, the SCOD removal with dosing frequency of 400 mg/L for every 5 d were highest in all reactors. The optimum dosing frequency of Fe2+ positively affected the microbial community structure. 16S rRNA gene sequencing revealed that the abundances of Firmicutes and Euryarchaeota were increased, which could enhance the hydrolysis-acidification and methanogenesis process during anaerobic digestion process.

To investigate the low-temperature oxidation characteristics of coal, programmed heating and oxidation experiments were conducted on single-particle-size coal samples from different mines. The inlet and outlet oxygen concentrations of the coal sample tank were measured to calculate the standard oxygen consumption rate (SOCR) of each coal sample at different temperatures. The relationship between the SOCR and temperature was fitted by an exponential function, and two regression coefficients ( A and B) related to the spontaneous combustion characteristics of coal were obtained, and the effects of both A and B on the spontaneous combustion of coal was analyzed. The results show that the A and B values are related to the physical structures and chemical properties of coal, respectively. Accordingly, taking the A and Bvalues of single-particle-size coal samples as the basic parameters, a new identification index describing the spontaneous combustion of coal is proposed. Compared with the chromatographic oxygen absorption method, the newly proposed identification index can reflect the degree of difficulty of spontaneous coal combustion more truly and intuitively. This research is of theoretical and practical significance for evaluating the characteristics of spontaneous coal combustion.

The extraction efficiency of high-gas coal seams is low in China with a large number of pre-drainage boreholes. In this study, we analyze the coal seam gas displacement mechanism using liquid carbon dioxide by combining theoretical analysis, experiments, and field tests. Changes of gas displacement efficiency with time under different displacement flow and pressure conditions are determined. We propose a coalbed methane displacement method using liquid carbon dioxide and apply the model in a field test carried out in well No. 2 of the Sangshuping coal mine. The results show that the injection of liquid carbon dioxide in coal seams is a pressure swing adsorption process. The effective displacement radius from the in-situ tests reaches 20 m. The maximum CH4 extraction concentration in the test area is 65%, which is 2.41 times higher than that of the original coal seam (27%). The maximum methane extraction flux rate is 0.884 m3/min, which is 2.34 times that of original coal seam (0.377). Implementation of liquid carbon dioxide displacement coalbed methane technology optimizes borehole arrangement and enhances coalbed methane extraction.

A series of experiments of the upward flame spread over polyethylene-coated wire with copper core were conducted in a newly designed high-pressure chamber to study the effects of the wire inclination angles and ambient pressures. The angle of inclination changed from 0° to 75° and the pressure ranged from 100 kPa to 400 kPa. The results show that the flame spread rate increases with the inclination angle and the pressure. The characteristic lengths including the flame length, the flame base width and the pyrolysis length present an increasing trend with increasing inclination angles, while the elevated pressure results in that the flame length and flame base width decreases and the pyrolysis length increases. Moreover, a simplified heat transfer analysis model considering the convective, radiant and conductive heat feedback is proposed to discuss the flame spread mechanism. Based on the theoretical analysis, convective heat transfer from flame and conductive heat transfer from wire core play significant roles in heating the unburned insulation with the increase of inclination angles. For the cases with higher pressure, the heat transfer from flame including heat convection and heat conduction plays a dominant role in increasing the heat feedback to the unburned wire.

Experiments were conducted in a 2 m large duct with an internal diameter of 70 mm, to investigate the effects of the vent area and ignition position on pressure oscillations with different methane concentrations. The results showed that violent pressure oscillations occurred when methane concentrations were between 9.5 and 12 vol. % in the closed duct. End ignition was shown to dampen the pressure oscillations to a significant extent. In addition, vented explosions could also reduce the pressure oscillations where the amplitude of the pressure oscillations decreases with increasing vented area. For a vent area of 38.5 cm2, no pressure oscillations occurred in all tests. Central ignition produced the larger pressure peak only when the vent area was small.

Electrical control boxes are common on high vapour cloud hazard sites, and in the case of the Buncefield explosion the ignition source was inside such a box, that was sited in an emergency pump house building. There has, however, been relatively little previous research into this type of ignition mechanism and its effect on the explosion severity. Commercially available electrical control boxes measuring 600 mm high, 400 mm wide and 250 mm deep were used to explore the pressure development, venting processes and flame characteristics of stoichiometric propane/air explosions using aluminium foil and the supplied doors as vent coverings. In some tests, the boxes were empty in order to establish a baseline for the effect of the internal congestion of the boxes. In other tests a congestion array was added. It was found that, in both the empty and congested box tests, the door produced a flat petal shaped flame, which differed drastically from the mushroom flame shape and associated rolling vortex bubble venting that is traditionally observed with large orifice vented explosions.

The flame propagation characteristics of hydrogen/methane/air mixtures with different hydrogen addition ratios (φ = 0, 10%, 20%, 30%, 40% and 50%) in different variable cross-section ducts were studied. A high-speed camera and pressure sensors were used to collect flame images and determine the overpressure dynamics. The results show that the smooth flame front will be twisted and folded, when the flame propagates to the abrupt position of the cross-section area of the duct. The larger the abrupt change rate of the duct cross-section is, the more obvious the disturbance to the flame and the more severe the turbulence. With increasing hydrogen addition ratio, the flame propagation speed and overpressure in the four kinds of variable cross-section ducts studied increase. The time for the flame front to reach the downstream end is gradually shortened, and the flame propagation time when the flame propagates from the smaller cross-section tube to the larger cross-section tube is more severely shortened with increasing hydrogen addition ratio than that when the flame propagates from the larger cross-section tube to the smaller cross-section tube. The increase of the overpressure caused by the addition of hydrogen is more significant when the flame propagates from the smaller cross-section tube to the larger cross-section tube. When the flame propagates from the smaller cross-section tube to the larger cross-section tube or from the larger cross-section tube to the smaller cross-section tube, the larger the abrupt change rate of the duct cross-section is, the larger the maximum overpressure.

Fire station plays an important role in ensuring the safety of people, property and environment. In order to improve the emergency rescue capability of the fire station, its influence factors are distinguished and a capability evaluation system is established in the present paper. The system is composed of goal layer, criteria layer and sub-criteria layer. The goal layer is the evaluation objective, namely, the emergency rescue capability of urban fire station. The criteria layer and sub-criteria layer contain five indexes and 25 indexes, respectively. Within the established evaluation system, the fuzzy comprehensive evaluation (FCE) method is chosen to analyze the decision problem. The weight of each index included in the system is determined based on the Analytical Hierarchy Process (AHP) method. Thus, the level of the emergency rescue capability of the fire station can be evaluated quantitatively. At last, a fire station in Zhengzhou city is taken as an example to verify the effectiveness of the established system. The results reveal that the emergency rescue capability of the fire station is in general level. Accordingly, the measures to strengthen the rescue capacity of the referred fire station are put forward.

Learning from process industry case histories is most often centred on management system elements, equipment components (including safety devices), and the actions of personnel that led to failure in achieving intended outcomes. Hence there can be a tendency to focus on things that went wrong. In this paper we explore the idea of focusing on things that went right – on events, resources, and concepts in which there is strong evidence of process safety success. It is concluded that learning lessons in this manner can serve as a helpful complement to the more traditional avenue of learning from process safety failure.

Due to their low sedimentation rate, nano-objects offer the opportunity to study flame propagation at low turbulence. The burning velocity was then estimated by flame visualization in two apparatuses: a vertical 1 m long tube with a square cross-section and a 20 L sphere equipped with visualization windows and a vent. This works aims to study the laminar burning velocity of nanocellulose by a direct visualization of the flame propagation within these devices. A high-speed video camera was used to record the flame propagation, and an estimation of the unstretched burning velocity was obtained through linear and nonlinear relationships relating the flame stretching and the flame velocities. Although these methods were initially established for gases, the organic nature of nanocellulose implies a fast devolatilization, which makes the application of the methods possible in this work. Similar results were obtained in both apparatuses in different turbulence conditions, proving the laminar burning velocity was approached. The laminar burning velocity for the nanocellulose was determined to be 21 cm s−1. This value, estimated through flame propagation visualization, was then compared to the value calculated by applying a semi-empiric correlation to the pressure-time evolution recorded during standard explosion tests in the 20 L vessel.

Radioactive 137Cs is one of the most common and problematic radionuclides in nuclear wastes. Decontamination typically involves passing the waste in continuous flow through an agitated or fixed bed reactor containing an efficient sorbent. There are many articles in the literature describing a broad spectrum of highly efficient sorbents. However,their properties is often difficult, mainly because the experimental conditions used differ. We describe the series of experiments that need to be performed to characterize Cs sorbents and illustrate by comparing three of these that, for the extraction of trace elements, the kinetics and selectivity of the exchange process are far more important than the maximum extraction capacity of the material.

Hybrid explosion experiments of hydrogen/aluminum dust in open space were performed. Aluminum dust with a median diameter of 56.18 μm was mixed with hydrogen at different volume concentrations (0%, 5% and 10%). Flame propagation was recorded by a high-speed camera. The explosion residues were observed by a scanning electron microscope, and their compositions were analyzed by X-ray photoelectron spectroscopy. The flame propagation velocities and structures, explosion residues and the combustion reaction mechanisms of hydrogen/aluminum dust mixtures were elucidated. The results show that the addition of hydrogen can increase the flame brightness and improve the continuity of the flame front. In the flame propagation process of a hydrogen/aluminum dust hybrid explosion, a micro-diffusion flame and asymmetric flame appeared simultaneously. Compared with pure aluminum dust combustion in air, when 5% hydrogen-air mixtures were used to disperse the dust, the flame propagation velocities decreased by 0.11-0.15 m/s. Attributable to a variety of intermediate products competing for oxygen and absorbing heat, the hybrid explosion residues cooled faster, porous oxide layers and incompletely oxidized aluminum spheres with small particle sizes were formed. The XPS showed that Al2O3, Al(OH)3, AlO(OH) and other complex products appeared in the combustion reactions. On this basis, a combustion model of hydrogen/aluminum dust hybrid explosion was established.

To investigate the overpressure of methane-air explosions in straight large-scale tunnels, the computational fluid dynamics (CFD) code of Flame Accelerator Simulator (FLACS) was used and validated against experiments conducted at three different scales, and the effects of the volume concentration of methane in air, the blockage ratio (BR), the tunnel length, and the cross-section were studied. When analysed using the GaussAmp mathematical model, the maximum peak overpressure appears at a volume concentration of 10.30% of methane in air. Blockage ratios (BR) of 0.15 and 0.3 resulted in the combustion of methane-air mixtures with the volume concentration of 6.5% and 14.0% of methane in air, producing a fatal overpressure of 21 kPa. When the BR increases up to 0.75, both the lean and rich mixtures cause a peak overpressure of over 60 kPa. Combustion of the same methane-air mixture produces the same overpressure, which decays approximately linearly at the same slope owing to a smooth wall roughness before travelling near the outlet, independent of the specific tunnel length. A method to characterise the cross-sections was proposed, and the maximum peak overpressure of different lengths of methane-air mixtures in different cross-sectional tunnels was found, presenting various regimes from a hump shape to a wave-like uplift and bowl shape. The cross-section parameters determine the degree of confinement and further control the maximum peak overpressure in the modelled tunnels. An exponential asymptotic model can be used to conveniently obtain the maximum peak overpressure. These phenomena indicate that approximately square-shaped cross-sections should be selected to avoid an extremely high overpressure in large-scale tunnels with the potentially significant accumulation of methane-air mixtures.

A new route of purification/revalorization of nickel electroplating wastewaters is proposed. It is shown that chemical treatment of different nickel-electroplating wastewaters with aqueous dispersion of layered structure amorphous potassium polytitanate (PPT) successfully removed the nickel from the effluents. Moreover, the resulting solid products, obtained with optimal PPT doses, showed excellent and consistent photocatalytic properties in the visible range of solar radiation, which are independent on the characteristics of the wastewater i.e. pH, nickel contents or the presence of other heavy metals. On the other hand, after proper dilution, the resulting treated effluents can be returned to the municipal wastewater collectors. The mechanisms of the processes taking place during the treatment are analyzed.

Nonlinear dependencies among highly correlated variables of a multifaceted process system pose significant challenges for process safety assessment. The copula function is a flexible statistical tool to capture complex dependencies and interactions among process variables in the causation of process faults. An integration of the copula function with the Bayesian network provides a framework to deal with such complex dependence. This study attempts to compare the performance of the copula-based Bayesian network with that of the traditional Bayesian network in predicting failure of a multivariate time dependent process system. Normal and abnormal process data from a small-scale pilot unit were collected to test and verify performances of failure models. Results from analysis of the collected data establish that the performance of copula-based Bayesian network is robust and superior to the performance of traditional Bayesian network. The structural flexibility, consideration of non-linear dependence among variables, uncertainty and stochastic nature of the process model provide the copula-based Bayesian network distinct advantages. This approach can be further tested and implemented as an online process monitoring and risk management tool.

Three-phase foam, namely surfactant-particle stabilized foam is a promising material in pool fire extinguishment. However, its effectiveness hasn’t been validated. In this study, a research-scale three-phase jet foam generator, which allowed adjustments of foam slurry composition, nozzle type, air flow rate and screen aperture, was developed. In order to optimize the foaming condition, a three-factor three-level Box-Behnken design (BBD) was adopted. Fly ash (FA) particles were used as the solid phase to generate three-phase foams. As a result, the FA supported foam exhibited better stability over conventional fire-fighting foam, especially when the particle concentration exceeded a threshold value. In addition, the BBD results presented a good agreement between experimental data and fitted models. The optimal foaming condition was determined by numerical optimization. Small-scale fire extinguishing experiments were carried out and three-phase foam manifested better burnback performance compared to conventional fire-fighting foam. The design in this work can be used to study the firefighting efficiency of different three-phase foams and serve as a prototype to develop better generators for both lab research and practical application.

Failure modelling and reliability assessment of repairable systems has been receiving a great deal of attention due to its pivotal role in risk and safety management of process industries. Meanwhile, the level of uncertainty that comes with characterizing the parameters of reliability models require a sound parameter estimator tool. For the purpose of comparison and cross-verification, this paper aims at identifying the most efficient and minimal variance parameter estimator. Hierarchical Bayesian modelling (HBM) and Maximum Likelihood Estimation (MLE) approaches are applied to investigate the effect of utilizing observed data on inter-arrival failure time modelling. A case study of Natural Gas Regulating and Metering Stations in Italy has been considered to illustrate the application of proposed framework. The results highlight that relaxing the renewal process assumption and taking the time dependency of the observed data into account will result in more precise failure models. The outcomes of this study can help asset managers to find the optimum approach to reliability assessment of repairable systems.

The advanced oxidation processes (AOPs), as an alternative technology to eliminate pesticides from aqueous environments, consist of several groups of technologies that have been used with high efficiency in the treatment of water and wastewater in recent decades. A systematic review of the scientific literature to evaluate the most common advanced oxidation processes (AOPs) for the removal of organophosphorus pesticides in aqueous matrices is addressed in this study. Meta-analysis is also performed to provide a precise and robust summary estimate after a systematic and rigorous integration of the available evidence. In the current study, 9 sub-groups of AOPs were reviewed, such as electrochemical, UV/H2O2 photolysis, photocatalysis, Fenton-type, plasma, gamma irradiation, sulfate-based catalyst, sonolysis and ozonation technology for organophosphorus pesticides degradation. The random effects model was used to estimate the pooled measurements and 95% confidence intervals (95% CI). In total, six studies were included in this review. All studies, except one, used the photocatalytic process as AOP. The average pooled percentage of AOP for pesticide degradation was 66.8 (95% CI: 58.1-75.6). In addition, the most studied pesticides are chlorpyrifos and diazinon which, according to the results of the meta-analysis, the photocatalytic process has the highest efficiency of diazinon elimination with an average percentage of 79.2 (95% CI: 76.8-81.5).

Tremendous amounts of oil and gas products are transported in pipelines worldwide resulting in increasing interest to identify the hazards and evaluate the associated risks associated with this critical infrastructure. Third-party intrusion is one of the least quantifiable factors being considered during the pipeline hazard assessment stage despite the substantial contributing to the total number of oil and gas pipeline incidents. This is because a probabilistic risk assessment cannot reliably model human actions and be applied to intentional acts. Due to the distinctive motivations of third-party damage, an unintentional third-party damage Bayesian Network model and a game-theoretic model on malicious intrusion will therefore be built, to examine the mechanism of pipeline failure caused by this mode. This study is conducted aiming at investigating pipeline risk resulting from third-party damage, and will formulate risk assessment models to identify threats, prioritize risks and determine which integrity plan should apply to different pipeline segments given the condition of third-party interference (both the accidental damage and malicious acts).

Liquefied natural gas (LNG) trade has increased globally; therefore, assessments of the hazards of its accidental release and associated consequences must be conducted to ensure LNG security during marine transportation. This study aims to understand the dynamic behavior occurring when an LNG jet is released underwater and the combustion behavior of a flammable vapor cloud on the water’s surface with airflows from 0 to 4 m/s. A series of controlled LNG vertical jet release experiments were conducted using a cryogenic storage tank with three orifices. Various instruments were employed to measure the flow rate and pressure in pipelines during different leakage scenarios, and the emanating LNG vapor clouds were immediately ignited with the mass loss rate of 0.016, 0.037, and 0.049 kg/s in three orifices, respectively. The flame behavior was recorded by a video camera. With respect to flame length rapidly decreased with crosswinds of 0-2 m/s and then gradually decreased to a constant value with the velocities increase to 4 m/s. A dimensionless number of Ri was employed to analyze the relative magnitude between the buoyancy force and transverse flow. The flame tilt angle was found in accordance trend with flame length for first increased and further reach to become constant at Ri-1 increase to 2. As existing correlations provide an overestimation, a new correlation was established to describe the flame length as a function of crosswind speed, and a good prediction was found for measured tilt angles with the correlated values.

Accurate calculation of the amounts of lost gas from coal are of great importance in underground mining. In this study, the effects of pore structure and the gas diffusion properties on the lost gas from tectonic and intact coals were investigated by the mercury intrusion porosimetry method (MIP), N2 (77 K) and CO2 (273 K) adsorption methods, and gas adsorption equilibrium/desorption tests. The results indicated that mesopore and macropore volumes increased after tectonic damage, as did the specific surface areas (SSA) and porosities. However, there was little change for the micropore volumes. Additionally, the desorption experiments indicated that the initial desorption and gas flow capacities of tectonic coal were greater than those of intact coal. Both laboratory and field results demonstrate that there is more higher lost gas for tectonic coal, which is directly influenced by the developed mesopore and macropore structure and by the initial gas desorption capacity. The logarithmic function method is a relatively better choice. When the gas content is determined in coal mines, the sampling exposure times should be kept as short as possible. From the perspective of engineering, this study provides a reference for the calculation of lost gas in tectonic coals.

As fault detection technologies have been developed, process fault diagnosis at early abnormal stage has come to be considered a major problem. In this work, a method to analyze the root cause of faults is developed to provide proper information at the early abnormal stage. First, principal component analysis (PCA) is used for the early detection of the process fault. Then, the contributions, from which the normal portion is removed, are decomposed by singular value decomposition (SVD) method to select the hierarchical sensors. Finally, the multivariate Granger causality (MVGC) method is used to construct the sensor causalities using the hierarchical sensors. The developed methodology is verified using the liquefied natural gas fractionation process model, which embeds a sufficient number of highly correlated sensors. The results are compared with the conventional principal component analysis method and amplification of the residual contribution method to verify the advantages of the proposed method.

Using batteries to convert chemical energy into electrical energy is one of the significant technologies that must be enhanced in the 21 st century. In the fuel battery development area, ionic liquids (ILs) are outstanding electrolytes for batteries. According to their thermophysical and phase equilibrium properties, ILs are widely used in different energy fields due to their diversity in the synthesis field. However, there are few detailed thermokinetic studies on ILs. To ensure the thermal safety of ILs in the process of creation, a commonly used IL, 1-butyl-3-methylimidazolium nitrate ([Bmim]NO3), was chosen for exploration. In this study, thermal decomposition characteristics were obtained by differential scanning calorimetry. The obtained data were input into the thermokinetic equation to determine the basic thermal hazards of [Bmim]NO3. In addition, based on thermal equilibrium theoretical models, the reaction kinetics and critical safety parameters were extrapolated for consideration. The influences of the sample mass and the overall heat transfer coefficient were simulated and discussed in 25.0 g and 50.0 g packages. The results showed that [Bmim]NO3 had a shorter TMRad and TCL (<1 day) when the temperature was greater than 200 °C. Moreover, SADT<150 °C can be used for evaluating the cooling system efficiency of [Bmim]NO3.

The possibility of using tannery raw wastewater as substitute for the nutrient supply in the anaerobic co-digestion of two tannery solid waste was investigated with regard to energy efficiency, waste treatment efficiency and economic efficiency. The results showed that the use of tannery wastewater as a source of nutrients for the AD of solid tannery waste proved to be adequate from the point of view that the three residues are being treated simultaneously. There was a biogas production of only 1.9 ± 0.3 mL/VSS. However, the percentage of methane in the biogas reached 33% at the beginning of the process, proving that there was methanogenic activity and that AD established. The cost analysis showed that there is a great reduction in the cost of wastewater treatment and solid waste disposal of 23% and 18%, respectively, in terms of electricity consumption and 11% and 8% respectively in terms of thermal consumption.

Risk matrices are widely used to present results of qualitative and semi-quantitative risk assessment for risk management decision making. There are different types of risk matrix category definitions according to the function and risk acceptance criteria. This paper reviews some general weaknesses of current risk matrices and proposes a method to improve the reading ambiguity of linguistically graded qualitative risk matrices. Main topic of this paper is the type of risk matrix that grades event consequence and frequency categories in linguistic terms. Because different people understand the meaning of these terms differently, the aim is to convert subjective quantified term inputs produced by a number of experts independently as much as possible to objective values creating at the same time a clearer and more discriminative result. In other words, the method involves asking various expert users independently to estimate numerical intervals of linguistic grades of event consequence and frequency on a continuous scale while maintaining risk acceptance levels. It is applying a second-generation fuzzy logic technique to express linguistic terms in numbers, called computing with words. This interval type-2 fuzzy system has evolved lately as a decision-making support tool and appears to be well suited to handle uncertainty intrinsic to qualitative linguistic grades, fusing different individual expert estimates in an objective way and to facilitate the reading resolution by introducing gliding numerical scales instead of discrete categories. Examples are given to illustrate the method as well as the use of the technique to aggregate a number of different qualitative risk matrix types into one unified risk matrix. The latter is useful in case a corporate-wide risk matrix exists to standardize risk management across the company, but older versions may still be around which should be fused with the newer ones.

As one of the main modes of damage caused by gas explosions in industrial production, the debris generated by the explosion threatens the safety of surrounding personnel and buildings. By means of experimental research and theoretical modelling, the debris generated by the vented component was experimentally studied, and a predictive model of the scattering range of explosion-induced debris was proposed. Through experiments using a self-designed explosion test apparatus, it is found that the gas explosion exerts a quasi-static pressure, and the vented plate is cracked by the plastic hinge under deflagration load. According to the force and the motion equation of the debris, the predictive model of the debris trajectory was proposed by differentiating the scattering process. The distribution of random variables in the model was determined by experimental data, and the scattering range of explosive debris was obtained using the Monte Carlo method. By comparing the calculated results with experimental data gathered under three typical conditions, the model values were seen to agree with the experimental values, and this model can predict the scattering range of debris. The proposed prediction model for debris scattering can provide a reference for the design of works used to protect against debris damage and subsequent domino effect.

This study introduces a new approach for designing a flare network system that ensures economic feasibility and safety using dynamic simulation analysis with the gPROMS ProcessBuilder software. A case of “separator outlet blocked discharge” was selected as a pressure-relief scenario based on the American Petroleum Institute Standard 521, and design data from a previous offshore project were used. As the main process and flare network system were dynamically simulated, the effects of the pressure, temperature, and liquid-level changes in the vessel on the opening of the pressure safety valve (PSV) were analyzed. Then, dynamic simulation results, including those for the flare load, PSV back pressure, and Mach number, were compared with those obtained from a steady-state model employing the Aspen Flare System Analyzer. Lastly, the sizes of the PSVs, branch lines, and main headers were optimized to minimize the overall capital costs and ensure the safety of the flare network system. This methodology can be applied to all existing and newly designed flare network system to enhance safety and reduce capital costs.

A combined experimental and numerical study was performed to improve the performance of the ventilation system in a mine refuge chamber (MRC). In the experiment, CO2 cylinders and dispersion pipes were used to simulate the CO2 release of 50 people, and 0.1 L/min per person of fresh air was provided by an air compressor. A new analytical model for a 50-person MRC was proposed and validated against the experimental data. Sensitivity analysis was carried out to investigate the effects of several control factors. The results indicated the following: (1) The ventilation system layout has a significant influence on the CO2 concentration distribution in an MRC, while the uniformity of the CO2 concentration distribution in the MRC may not be effective with increased number of air inlets. (2) Under a well-arranged ventilation system in the 50-person MRC, the average CO2 concentration can be controlled at less than 0.5% with a ventilation rate of 0.1 m3/min per person, and less than 0.2% with a ventilation rate of 0.3 m3/min per person. (3) A quantitative correlation exists between the CO2 concentration and ventilation volume rate, as well as the CO2 release rate, for an MRC under a well-arranged ventilation system.

Ventilation air methane in coal mining has an important environmental impact, since methane is a strong greenhouse gas (1 kg of methane is equivalent to 28 kg of carbon dioxide). The oxidation of methane in regenerative oxidizers can be an attractive technique to exploit this resource. Thus, part of the heat released by the reaction can potentially be recovered, in addition to decreasing methane environmental impact. However, the concentration of methane in the mine ventilation air may change considerably with respect to the oxidizer design value, which have negative consequences. An increase in concentration can produce overheating (with possible damage to the unit), while a decrease in concentration may cause the extinction of the reaction. In this work, three control systems have been considered in order to deal with these issues: proportional-integral-derivative (PID) and proportional-integral (PI) feedback controllers, and model predictive controller (MPC). The control action is based on regulating the heat extracted from the oxidizer by adjusting a hot gas purge from the centre of the reactor. First, the control systems have been designed (i.e. the tuning parameters of the controller have been calculated). To carry out the design of the controllers, a simplified dynamic model was obtained from a complex model of the oxidizer. Then, the performance of the controlled oxidizer has been simulated for different types of disturbances. In these simulations, the simple PID controller performed well, and the MPC exhibited the fastest response.

Sulfur oxidizing bacteria have been widely exploited to remove thiosulfate with adverse effects on human health and environment. Since formation of elemental sulfur among other thiosulfate oxidation products is advantageous in industrial applications, we tend to statistically screen (fractional factor design) and optimize (response surface methodology) the operating conditions in this study so that the final thiosulfate removal (Y1) and the highest sulfur production (Y2) become maximum along with the appropriate final sulfate formation (Y3). Optimum conditions were then examined in a stirred bioreactor. Screening results showed the definite effectiveness of six factors on all responses however level modification and optimization were necessary due to significant P-value of curvature. Single response optimizations (maximization of each response) resulted in dissimilar sets of optimal conditions. Multiple response (Y1 = 100%, Y2 and Y3 = 50%) optimization, using desirability function, was therefore used and resulted in agitation speed: 44 rpm, pH: 6.07, temperature: 24.7 °C, time: 2.64 day, inoculum ratio: 19.5% and thiosulfate level: 2.87 mg l-1 as optimal conditions. Bioreactor experiments (agitation speeds: 40-60 rpm) under optimal conditions led to the highest S0 formation of 46% and complete thiosulfate removal at 60 rpm and 40 h. Therefore, multiple response optimization followed by minor scale modifications can productively enhance industrial elemental sulfur formation from wastewater plants.

A novel rotating advanced oxidation contactor (RAOC) equipped with high-silica zeolite/TiO2 composite sheets was applied to remove sulfamonomethoxine (SMM) and its transformation byproducts from fresh aquaculture wastewater (FAWW). Adsorption and photocatalysis of SMM was not interfered by coexisting substances in the FAWW. The combination of adsorption and photocatalysis by the RAOC degraded SMM more rapidly than photocatalysis alone, possibly because of the synergetic effect. Moreover, the increase in UV fluence rate (UVFR) enhanced SMM degradation, and the linear relationship between UVFR (0.9–3.6 J/cm2/h) and the rate constant for SMM degradation was observed. The removal behavior of the transformation byproducts generated via hydroxylation of the aromatic ring of SMM was investigated, and their degradation was inhibited by the coexisting substances. The RAOC treatment was repeated five times without exchanging the composite sheets to evaluate the reusability of the composite sheet. The RAOC stably and completely eliminated SMM from the FAWW, showing the zeolite was regenerated by the photocatalysis of SMM adsorbed in the composite sheets. The results demonstrated that the RAOC effectively and stably removed SMM and its transformation byproducts from the FAWW.

The risk of road transportation of flammable liquid is of great uncertainty due to the time-varying conditions of the passing locations and the environment, which leads to challenging risk analysis. In this work, a real-time risk analysis method for road tanker transportation based on the fuzzy Bayesian network (FBN) is proposed. The bow-tie model is first employed to identify hazards in flammable liquid road transportation systems and shows risk evolution. The framework of the Bayesian network (BN) is then determined accordingly. In the case that the historical statistics of accidents are limited, a probabilistic estimation model that combines expert judgment and fuzzy set theory is established to determine the prior probabilities and the conditional probabilities of the BN nodes. Case studies of typical road tanker transportation accidents were carried out to show the risk level variation with both the internal and external conditions at different moments. Sensitivities of the parent nodes were analyzed, and the critical factors leading to accidents were identified. Studies show that this method can dynamically characterize the changes in both the probabilities and the consequence levels of road tanker transport accidents. Based on the vehicle’s GPS data and the local environment, the proposed method can provide an estimation of the real-time risk for road tankers.