Ignition Hazards Research Articles

Comparing the safety of bunkering LH2 and LNG using quantitative risk assessment with a focus on ignition hazards

Liquid hydrogen represents a potential candidate for a climate neutral fuel for shipping. The utilization of this fuel necessitates the implementation of safe and reliable bunkering operations. This paper employs a quantitative risk assessment to compare the safety of bunkering liquid hydrogen with the safety of bunkering LNG. Initially, a frequency analysis is conducted using an event tree. It can be demonstrated, that the occurrence of the hazardous events, pool fire, flash fire and explosion, is more frequent with liquid hydrogen than with LNG. In the second step, the consequence analysis determines necessary safety distances for the hazardous events under consideration. For the events of pool fire and explosion, LNG-bunkering requires higher safety distances. Liquid hydrogen-bunkering requires higher distances for flash fire event. Since the safety distances for flash fire events are largest, they define the distances for the system. However, the consequences of flash fire events are subject to greater uncertainties and require further investigation. Overall, hazardous events occur more often with liquid hydrogen-bunkering, but LNG-bunkering requires in two out of three cases larger safety distances.

Electrostatic charging of material webs in production machines and how to eliminate it

The elimination of electrostatic charges, especially on material webs is critical to preventing ignition hazards and personal injury hazards in industry. The use of discharge bars (called “ionizers”) is an important method for eliminating electrostatic charges.The possibility of electrostatic discharge in a production machine is real. The metrological detection of charges on material webs is also discussed and the special phenomenon of a super brush discharge is described. A useful arrangement for active ionizers is described and justified.

Static ignition hazards with plastic containers

AbstractPlastic containers present unique challenges in flammable liquid service, as most plastics are highly electrically insulating, cannot be grounded, and can easily accumulate electrostatic charges. These electrostatic charges result in elevated risks of electrostatic ignitions where the potential for ignitable mixtures exists, including unique and different exposures on the inside and outside surfaces of plastic containers. In this primer, four specific ignition risks are overviewed: (1) flow electrification, (2) splash filling, (3) triboelectrification, and (4) charge accumulation on workers.

Parameters Influencing Space Charge Density in Vessels by Spraying Water

Spraying water in vessels generates electrostatically charged clouds of droplets. If the resulting space charge density is sufficiently high, brush discharges to conductive earthed parts may occur. In vessels where potentially explosive atmospheres might occur, the prevention of hazardous space charge density is required. This work gives an overview of all the relevant parameters that influence the space charge density. For this purpose, own measurements are presented and compared with knowledge from the literature. The measurements have been carried out with earthed vessels and nozzles built of conductive material. To take the state of the art into account, pump pressures of up to 2500 bar have been used. The result of this work provides support for dimensioning vessels and water spraying techniques to minimize the risk of ignition hazards due to brush discharges of the electrostatically charged clouds of droplets.

A method of risk assessment for static ignitions

This paper presents a method of risk assessment for static ignitions that can be widely used overseas. It describes how the developed risk assessment method identifies static ignition hazards and analyses static ignition risks. This method has been developed on the basis of the flow of procedures in IEC/ISO Guide 51, lessons learned from incidents over 50 years and the survey of the situation of electrostatic risk assessment in Japanese industry, and has been maintained as an implementation guide to assist safety managers since 2008. The method includes a process/operation review; hazard identification for explosive atmosphere formation, charging, electrostatic induction and electrostatic discharges; static ignition risk estimation and evaluation; and risk reduction countermeasures. Tools are also provided to aid implementation: a risk assessment sheet to follow the method and record the results, and 30 check items to identify static ignition hazards. The method with the guide has been adopted by many safety managers in Japan.

Ignition risk assessment to the non-electrical equipment from hydrogen production, storage, transport and use facilities

The goal of integrated explosion safety is a concept that was developed to prevent the formation of explosive atmospheres as well as sources of ignition and, in the event that an explosion does take place, to immediately stop to it and/or to limit the damage it causes. Ignition of explosive atmospheres by non-electrical equipment occurs when energy supplied by equipment used for processing or conveying of material is converted into heat, usually as the result of a mechanical failure of the equipment or associated systems. In light of this fact, the manufacturer has a responsibility to take precautions with regard to the potential ignition sources. In addition, the non-electrical equipment must be designed and manufactured after a thorough analysis of the possible operating faults. This is done in order to prevent potentially dangerous situations as much as possible by taking into account any misuse that can be anticipated in a reasonable manner. The most important aspect of the ignition hazard assessment for the non-electrical equipment is the identification of the probable ignition sources. The paper shows the methodology of the ignition hazard assessment for the non-electrical equipment intended for use in potentially explosive atmospheres.

Investigations on ammonium O, O dicetyl dithiophosphate (ADCTP) as a novel antistatic additive for kerosene fuel - an exploratory study

In this study, an organic ligand ADCTP (Ammonium O, O dicetyl dithiophosphate) was synthesized and used as an antistatic additive for the first time in the kerosene fuel. The ignition hazard assessment of the ADCTP dispersed kerosene fuel was evaluated from three aspects: Physical phase structure analysis, thermal analysis and process safety parameters analysis. The physical state and thermal analysis were characterized using experimental techniques such as UV visible spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FTIR), Nuclear magnetic resonance (NMR) and Thermogravimetric analysis (TGA). In order to determine the process safety parameters, the antistatic doped fuel was manifested in terms of electrical conductivity, thermal conductivity, viscosity, stability, aging, and relaxation time. The results indicated an enhancement of electrical conductivity of the kerosene fuel up to 790 pS/m for 1000 ppm addition of ADCTP ligand and it will dissipate the generated and accumulated static charges. The ADCTP dispersed fuel was found to be thermally stable up to 200 °C. A laudable reduction in the relaxation time of static charges from 3 sec to 0.04 sec was also observed. This study revealed that, the organic ligand ADCTP is found to be a potential additive to reduce the ignition hazards.

Fuzzy Structured Element Integrated Decision of Metamorphism on Coal Dust Ignition Hazard Rating

To discuss the coal dust ignition hazard rating of different metamorphism, the fuzzy structure element integrated decision model about “no danger”, “weak danger”, “general danger”, and “strong danger” of coal dust ignition is established. 40 kinds of coal samples are selected to carry out coal quality analysis test, overpressure test, temperature test, flame propagation properties test and particle size distribution test. Based on this, coal dust ignition hazard rating decision-making index system is built. The triangular structure element is added to fuzzy comprehensive decision model, by sequencing weighted Hamming distance between fuzzy index value function and fuzzy maximal function, the coal dust ignition hazard rating of different coal quality can be decided. The result shows that: with increasing metamorphic grade, coal dust ignition hazard rating is decreasing, which provides study basis for relation between metamorphism and ignition hazard rating.

Application Assessment of Electrical Cables during Smoldering and Flaming Combustion

Electrical cables are a potential source of ignition and fire hazards in various types of buildings and industrial installations, as well as in all modes of transportation, including aircraft. Fires in buildings pose the greatest threat to human life and health. The composition of thermal degradation products depends mainly on the type of combustible materials and the type of combustion process—flaming or smoldering. The purpose of this paper was to determine, based on experimental studies, the effects of flaming and smoldering combustion on the response times of fire smoke detectors. In addition, the concentrations of fire gases formed in the process of duct combustion, including CO, SO2, NO2, NO, HCN, HCl, HBr and HF, were measured using an FTIR spectrometer. The results presented confirm the significant effect of the way the cable samples burned on detector tripping time. The highest concentration of smoke (Y) in the test chamber was obtained during flame combustion. It was further found that the characteristics of the cable insulation material used, such as the type of PVC, had a significant effect on the toxicity of the emitted gases. The largest amounts of toxic gases were emitted during the smoldering combustion of a cable with a plasticized PVC sheath.

Minimum ignition energy of hydrogen-air mixtures at ambient and cryogenic temperatures

The ignition and combustion of hydrogen in air is considered more hazardous compared to other fuels due to the lower minimum ignition energy (MIE) and the wider flammability range. Spark discharge is the most common type of electrostatic ignition hazard. There is a need in validated safety engineering tools to accurately calculate MIE in a wide range of temperatures from atmospheric to cryogenic which are characteristic for hydrogen systems and infrastructure. Current MIE assessment methodologies rely on the availability of experimental data on quenching distance and/or laminar burning velocity and thus are mostly empirical correlations. This prevents their application beyond the limited number of experimental data, i.e. to arbitrary composition of the hydrogen-air mixture at arbitrary temperatures including cryogenic. This work aims at the development of a model able to accurately predict MIE for hydrogen-air mixtures with arbitrary initial composition and temperature. Cantera and Chemkin software are used to calculate the properties and unstretched laminar burning velocity of hydrogen-air mixtures. The flame thickness is found to well represent the critical flame kernel in the suggested model. The model is validated against experimental data on MIE for mixtures at ambient and cryogenic (down to 123 K) temperatures. Results show that the effect of flame stretch and preferential diffusion shall be considered to accurately predict MIE for lean hydrogen-air mixtures, which was not possible for previous models.

A Method to Determine the Chain Pillar Width considering Coal Burst and Goaf Ignition Dual-Hazard Management

Abstract High rock stress and ground temperature pose great threats to the routine production of longwall top coal caving (LTCC) panels. In this risky condition, the width of the chain pillar is considered a factor adjustable for controlling coal burst and goaf ignition hazards. However, a contradiction, as suggested by longwall experience, is that narrowing the pillar helps coal burst prevention but negatively leads to higher self-ignition potentials, while widening the pillar restrains goaf ignition but increases the likelihood of coal burst. This paper conducted a case study on a longwall panel from Tangkou Mine, China. The paper first analysed stress, elastic strain energy, and goaf temperature variation with varying pillar widths, by which the coal burst risk index δr and goaf ignition risk index Qs were defined and correlated to pillar width D. Further, a pillar width determination method considering coal burst and goaf ignition dual-hazard management was developed by means of the operating point principle. By this method, a reasonable width range was defined by plotting both correlation curves δr=fD and Qs=gD on a chart, followed by optimal width determination according to the intersection of both curves and further verification via a field trial.

A Shared Method of Metal Object Detection and Living Object Detection Based on the Quality Factor of Detection Coils for Electric Vehicle Wireless Charging

High power alternating magnetic fields can cause lesions and pathological changes in living object bodies entering the wireless charging area. Also, as for metal objects, the eddy effect can cause the security risks such as fire and ignition hazards. Hence, metal object detection (MOD) and living object detection (LOD) are the necessary functions for a wireless power transfer (WPT) system. A shared method of MOD and LOD based on the quality factor of detection coils for electric vehicle wireless charging was proposed in this paper to realize the dual functions by the same detection coil array. Firstly, the effect of metal objects and living objects on the detection coil quality factor was analyzed in detail. Secondly, a method of real-time calculation of quality factor was proposed to detect whether the foreign object exists. Then, a distinction algorithm based on the phase variation trend of resonant capacitor voltage was designed to classify the type of foreign objects. Finally, a 3.3 kW experimental prototype, including a foreign object detection (FOD) system, was established to verify the validity. The advantage of the quality factor as the core indicator for FOD was analyzed in detail. Under the condition of an iron wafer, aluminum wafer, and beef chunk placed on the detection coil, the quality factor calculation results of the detection coil in contrast to those without foreign objects decreased by 80.8%, 50.5%, and 69.9%, respectively. Meanwhile, the phase difference of the excitation relative to the resonant capacitor voltage changed -61.3°, -74.6°, and 49.4°, respectively.

Determination of the Self-Ignition Behavior of the Accumulation of Sludge Dust and Sludge Pellets from the Sewage Sludge Thermal Drying Station

Sewage sludge may pose a fire risk. The safe storage of biomass waste is a challenge due to self-heating processes. This study aims to assess the propensity to spontaneously combust of sewage sludge in order to determine safe storage and transport conditions. The evaluation of spontaneous ignition hazard was assessed according to EN 15188, by the determination of the self-ignition temperature. Certain parameters assumed to affect the inclination of sewage sludge to self-ignite, including the moisture content, bulk density, elemental composition, and particle size, were discussed. The results showed the risk of self-ignition during the storage and transport of sludge dust and pellets. The usage of the smallest basket volume resulted in the highest self-ignition temperatures, which were 186 °C and 160 °C for sludge pellets and dust, respectively. The comparison of the two forms of thermally dry sludge showed, that despite sludge pellets being easier to store and handle issues, the more favorable conditions for the management in terms of fire risk is sludge dust. Its temperatures for safe storage are slightly higher. The results highlighted that future research should focus on the hazards of silo fires and explosions in terms of silo fire prevention and management.

Fire hazards of PMMA-based composites combined with expandable graphite and multi-walled carbon nanotubes: A comprehensive study

Due to their environmentally friendly features, expandable graphite (EG) and carbon nanotubes (CNT) were widely used as an additive in the field of flame-resistant polymers. However, the addition of EG or CNT improves heat and mass transfer in polymers, which in theory might hasten the rate of flame spread and hence raise the fire danger associated with polymers. Thus, LOI, CCT, and horizontal flame spread tests were carried out to comprehensively reveal the effects of the addition of EG and MWCNT on the fire risk of thermoplastic polymers. Results show that EG and MWCNT were antagonistic when functioning in PMMA together, despite the fact that both of them had good effects on flame retardancy when acting in PMMA alone. Additionally, the addition of EG and MWCNT to the PMMA increases the flame height and hastens the flame spread. The comparison of results between LOI with CCT and the flame spread test shows the addition of flame retardants in thermoplastic polymers will diminish the hazard of fire ignition and heat release while raising the hazard of flame spread, which suggests the fire hazard of thermoplastic polymers with flame retardants deserve comprehensive assessment when new types of flame retardants to be created.

Study on derived hydrogen and ignition influencing factors of moist magnesium debris

While active metallic magnesium is extensively employed, the generated magnesium debris is prone to derive hydrogen gas during storage, which poses potential explosion hazards. Therefore, a 1 L micro-reaction device and test system were self-designed to study the variation law and ignition hazard of hydrogen gas derived from moist magnesium debris. It was discovered that the hydrogen content derived from moist magnesium debris and system temperature both exhibited a variation law of first increasing and then decreasing with increasing moisture content. The higher the initial temperature, the smaller the size of magnesium debris, and the more accumulation layers of magnesium debris, then the faster the hydrogen production rate of moist magnesium debris, and the higher the ignition sensitivity of the system. It also aroused the peak of the variation curve of derived hydrogen increase value and system temperature increase value to shift towards the larger moisture content. Evidently, apart from the risk of dust explosion, the risk of hydrogen explosion deserves more attention when the active metal dust has been accumulated over a long period. It is very necessary to adopt ways and means to suppress hydrogen explosions. The research results offer a reference for the hazard rating classification of industrial active metals in storage, transportation, and other key aspects under different working conditions.

Exploring the efficacy of various surfactants on the kerosene fuel and its electrical conductivity responses

In this work, for the first time, various surfactants such as oleic acid, oleylamine, Tween 20 and Span 20 were used as static dissipating additives (SDA) for kerosene fuel to enhance their electrical conductivity. The ability of the surfactant dispersed kerosene fuel to store, transport, and process was revealed in terms of process safety parameters such as electrical conductivity, retention period, and viscosity. The results indicated an enhancement of the electrical conductivity of the kerosene fuel up to 1689 pS/m for a 500 ppm addition of surfactants. The surfactant dispersed fuel was measured for electrical conductivity with a varying temperature range from 30 to 70 °C. The addition of 0.05% by weight surfactants increased the viscosity of the kerosene fuel by 20.7%, however, without degrading the fuel quality. A laudable reduction in the retention period of 10 days was also observed. This study revealed that the surfactants selected in this study are found to be potential additives to reduce the ignition hazards of kerosene fuels.

Experimental study on the minimum ignition energy of cornstarch particle-air flows in a horizontal pipeline

Pipelines and process equipment are commonly interconnected in a network of dust extraction or pneumatic conveying in lines industry. History has shown that the severity of a dust deflagration could be much accentuated if the initial fireball is allowed to propagate further through pipelines. However, less is known about the hazard of a primary ignition in a pipeline conveying system with combustible dust and high airflow velocity. This paper presents an experimental study on the ignitability of cornstarch particle-air flow in a lab-scale piping system. The results show that minimum ignition energy (MIE) of dried cornstarch flow at 12–28 m/s was less than 300 mJ, and the minimum explosible concentration (MEC) was less than 100 g/m3. An increase in airflow velocity increased both MIE and MEC, as well as stretching the spark plasma. Moisture in the dust significantly decreased its ignitability, with this being a more marked factor than airflow velocity in influencing the ignition hazard in a pipeline.

Computational Design to Suppress Thermal Runaway of Li-Ion Batteries via Atomic Substitutions to Cathode Materials.

The cathode material of a lithium-ion battery is a key component that affects durability, capacity, and safety. Compared to the LiCoO2 cathode material (the reference standard for these properties), LiNiO2 can extract more Li at the same voltage and has therefore attracted considerable attention as a material that can be used to obtain higher capacity. As a trade-off, it undergoes pyrolysis relatively easily, leading to ignition and explosion hazards, which is a challenge associated with the application of this compound. Pyrolysis has been identified as a structural phase transformation of the layered rocksalt structure → spinel → cubic rocksalt. Partial substitution of Ni with various elements can reportedly suppress the transformation and, hence, the pyrolysis. It remains unclear which elemental substitutions inhibit pyrolysis and by what mechanism, leading to costly material development that relies on empirical trial and error. In this study, we developed several possible reaction models based on existing reports, estimated the enthalpy change associated with the reaction by ab initio calculations, and identified promising elemental substitutions. The possible models were narrowed down by analyzing the correlations of the predicted dependence of the reaction enthalpies on elemental substitutions, compared between different reaction models. According to this model, substitution by P and Ta affords the highest enthalpy barrier between the initial (layered rocksalt) and the final (cubic rocksalt) structures but promotes the initial transformation to spinel as a degradation. Substitution by W instead generates the barrier to the final (preventing dangerous incidents) process, as well as for the initial degradation to spinel; therefore, it is a promising strategy to suppress the predicted pyrolysis.

Pros and cons of non‐sparking tools

AbstractAn explosion occurred on December 23, 2021 at the ExxonMobil Baytown Complex, Baytown, TX., USA. Within a week, a lawsuit was filed claiming that a contractor “using a wrench essentially as a hammer, created a spark causing the flammable gas to ignite.” This event served as an incentive to remind readers of Process Safety Progress of situations where non‐sparking tools are required by Code for work in specific flammable environments, along with the pros and cons surrounding their more general use. The potential for metal impact sparks can be overlooked by inexperienced maintenance workers, contractors, engineers, and other personnel unaware of all the hazards of working in flammable atmospheres. The debate about whether a truly “non‐sparking” tool exists or whether a metal–metal impact spark is a significant ignition hazard, other than for easily ignitable gases and other special cases, is beyond the scope of this article. Instead, we provide a discussion of potential and recognized hazards with reference to applicable Codes and Regulations.

Обеспечение электростатической искробезопасности применения стеклопластиков в технологических трубопроводах, аппаратах и оборудовании

The number of the insulating materials, including fiberglass products, are widely used in the construction, industry, oil and gas facilities, agro-industrial complex, transport, and defense. When using fiberglass, like some other insulating materials, it is possible to encounter their destruction and perforation, followed by a transition to the source of double-sided corona effect. Sliding spark discharges of static electricity, capable of igniting a combustible or explosive environment, are also likely to occur. The formation of such discharges depends primarily on the electrostatic and electrical strength properties of the used materials. These parameters should be used when assessing the most dangerous consequences of the fiberglass application in the process pipelines, apparatus, and equipment under the conditions of electrification processes. Comparison of the electrostatic and electrical strength properties of the corona-forming air layer in the electrization processes with the similar indicators of non-conductive structural materials is the main criterion that determines the possibility of their perforation and the occurrence of spontaneous sliding spark discharges. Electrostatic intrinsic safety should be ensured by eliminating static electricity discharges that are capable to become the flammable substances source of ignition (materials, mixtures, products). Sliding sparks can be eliminated by managing the electrostatic load. But at the same time, the hazard of ignition by discharges would remain if they could occur. When replacing the metal element (the wall of an apparatus or vessel) electrified by a liquid (technological medium), a product made of an insulating material, including fiberglass, with similar geometric, technical, and operational parameters, it is possible to maintain the efficient protection of the metal structure by means of its grounding.