Modified Setup of 20-L-Sphere for the Determination of Safety Characteristics of Nano Powders (original) (raw)

Assessment of Explosion Hazards Associated With Nano-Powders

SPE Kingdom of Saudi Arabia Annual Technical Symposium and Exhibition

Nano-powders are composed of particles in size range from about 1 to 100 nano-metres (nm). The growing demand for nano-powders arises from the change in physical, chemical and electrical properties exhibited by such particles when their size falls below 100 nm. Along with the increasing production and use of Nano scale particles, there has been a growing concern over the impact of this new technology on health, safety and environment. This has almost exclusively concentrated on the potential health hazards of nano-powders. One potential hazard that appears to have received little attention to date is their explosivity. Explosive dust clouds can be generated from most organic materials, many metals and even some non-metallic inorganic materials. Dust explosions involving particle sizes ranging from a few microns to hundreds of microns, there is a need for these particles to be extensively studied. This work involves computationally modelling the explosion, and investigation of critical parameters that can enhance the severity of the explosion. These parameters include but are not limited to effect of particle size, dust concentration and composition, ignition strength, degree of dust dispersion, explosion characteristics of nano-particles, operating conditions. Further, the work involved in this paper looks at the impact onto the environment by explosion of such nano-powders. The possibility of dust generation accumulation and explosion in various areas of the facility are investigated. A checklist for adequacy of existing safety measures is prepared, and requirement for additional safeguards is studied, in order to avoid catastrophic effects.

Ignition and explosion characteristics of four kinds of nanopowders

Journal of Physics: Conference Series

This work is about the study of ignition sensitivity and the explosion violence characteristics of nanoparticles. It was carried out on various nanopowders as part of a project (NANOGRA) that aims at a multidisciplinary assessment of the risks related to nanoparticles. This paper discusses the experimental results for the determination of ignitability and explosion violence characteristics of Thermal Black N990, Corax N550, MWCNTC7000 and partially passivated metallic nanoparticles (Aluminium). The results of the various tests (MIE, Pmax and KSt) led to the conclusion that carbon nanopowders are capable of generating , when airborne, an ATEX with moderate explosion intensity comparable to the ST1 class. They are little sensitive to electrostatic phenomena. The assessment of explosion parameters of carbon nanopowders was generally found similar to their microscopic size analogue. The pyrophoric nature of partially passivated aluminium nanopowder required screening tests (e.g. MIT layer and combustibility) to control the risk of ignition in the stages of the characterization tests.The results show that aluminium nanoparticles are sensitive to the risk of ignition by a phenomenon of electrostatic origin, and explosion violence seems to decrease when BET specific surface area increases.

Risk assessment of the ignitability and explosivity of aluminum nanopowders

Process Safety and Environmental Protection, 2012

Previously, an extensive study has been carried out in order to assess the ignition sensitivity and explosivity of aluminum nanopowders. It showed notably that, as the particle size decreases, minimum ignition temperature and minimum ignition energy decrease, indicating higher potential inflammation. However, the explosion severity decreases for diameters lower than 1 m. As a consequence, this study leads to the conclusions that the ignition sensitivity and explosion severity of aluminum nanopowders may be affected by various phenomena, as pre-ignition, agglomeration/aggregation degree and the intrinsic alumina content. The presence of wall-quenching effects and the predominance of radiation compared to conduction in the flame propagation process have to be discussed to ensure the validity of the 20 L sphere and of the results extrapolation. Based on the peculiar behaviours that had been previously highlighted, a specific risk analysis has been developed in order to assess the fire and explosion risks of such materials. It has been applied to an industrial plant of aluminum nanopowders production. The hazard identification and the consequence modelling steps, especially the quantification of the likelihood and consequences, have been designed specifically. The application of this method has led to the definition of the most adequate safety barriers.

Explosivity and Flammability of Nanopowders: New Challenges

2019

Despite a number of studies, the information about the multifaceted dangers associated with the manufacture, transport and storage of nanopowders remains insufficient and justifies the initiative of the NANOGRA project: Nano Global Risk Assessment. The latter aims at a multidisciplinary study (flammability and explosivity, toxicological and eco-toxicological risks) of potential risks related to nanomaterials and nanoparticles with prior economic interest in the Walloon Region. This paper discusses the experimental results of determination of the ignition sensitivity and explosivity characteristics of Carbon Black N990, Corax N550, MWCNT MC 700 and partially passivated metallic nanoparticles (Aluminum). Key information regarding MIE, Pmax and Kst values was obtained for carbon nanopowders. The results of the different tests have led to the conclusion that the carbon nanopowders are capable of generating an ATEX during suspension in the air, with moderate explosion intensity comparabl...

Thermal and sensitivity analysis of nano aluminium powder for firework application

Journal of Thermal Analysis and Calorimetry, 2011

The performance of the fireworks is governed by the sound level it produces. As per Govt. of India notification, crackers sound level should not exceed 125 dB (AI) or 145 dB(C) pk. In this study, nAl powder was synthesised at different particle sizes of 113, 187 and 218 nm as a fuel. These powders are well mixed with the oxidizer (KNO 3) and the igniter (S), and the cake bomb was manufactured with various compositions and checked for their performance. The thermal analysis was performed by DSC and DTA, and the impact sensitivity was analysed for all compositions. The nano-sized chemicals showed high thermal energy content and high sensitivity for various compositions. Further it is observed that the nAl chemical for producing the optimum sound level in the cake bomb has been reduced to 62.5% when compared with lm powder.

Research into nanoparticles obtained by electric explosion of conductive materials

Surface Engineering and Applied Electrochemistry, 2011

One of the primary nanoparticles production methods is electric explosion of wire (further -EEW) which is known as a physical phenomenon since 1771. Limitation of EEW as a method of nanoparti cles production lies in a great dispersion of particle diameters -a spectrum of nano and micrometric diam eters (10 3 and higher differences in diameters are likely). Due to great differences in nanoparticles diameters formed by explosion (in aerosol conditioned by explosion), a continuous separation of nanoparticles from aerosol flows is essential. Dispersion of conductor explosion products is mostly affected by a diameter of wire, density of comparative energy, duration of the energy input. Objective of this research is to investigate the vista of producing nanoparticles by EEW at low voltage and high energy surplus using the wire of an enlarged diam eter. Analyses have been made by exploding the iron wire of 60 mm length and 0.31 and 0.45 mm diameter and the copper wire of 0.375 and 0.49 mm diameter. Purity of the wire material was 99.5% of iron and 99.9% of copper. To separate nanoparticles from aerosol a separation device was used which consists of a precipitator and three stages centrifugal cyclone. SEM analysis of Fe nanoparticles using SEM showed the mean diameter of particles about 69 nm (for wire ∅0.45 mm). Cu nanoparticles was 97 nm in diameter (for wire ∅0.49 mm). XRD spectra of iron and copper nanoparticles indicated a high oxidation level of Fe and Cu (oxides of differ ent crystollagraphic axes are formed such as Fe 3 O 4 , Fe 2 O 3 , CuO, Cu 2 O). A moderate quantity of pure Fe and

Applications of dust explosion hazard and disaster prevention technology

Powdered materials are widely used in industrial processes, chemical processing, and nanoscience. Because most flammable powders and chemicals are not pure substances, their flammability and self-heating characteristics cannot be accurately identified using safety data sheets. Therefore, site staff can easily underestimate the risks they pose. Flammable dust accidents are frequent and force industrial process managers to pay attention to the characteristics of flammable powders and create inherently safer designs. This study verified that although the flammable powders used by petrochemical plants have been tested, some powders have different minimum ignition energies (MIEs) before and after drying, whereas some of the powders are released of flammable gases. These hazard characteristics are usually neglected, leading to the neglect of preventive parameters for fires and explosions, such as dust particle size specified by NFPA-654, MIE, the minimum ignition temperature of the dust cloud, the minimum ignition temperature of the dust layer, and limiting oxygen concentration. Unless these parameters are fully integrated into process hazard analysis and process safety management, the risks cannot be fully identified, and the reliability of process hazard analysis cannot be improved to facilitate the development of appropriate countermeasures. Preventing the underestimation of process risk severity due to the fire and explosion parameters of unknown flammable dusts and overestimation of existing safety measures is crucial for effective accident prevention.

The Explosion and Dispersion Potential of Engineered Nanoparticles

2016

This work investigates the explosion and dispersion potential of engineered nanoparticles (ENP). The European Union (EU) sponsored this investigation, firstly to predict or estimate risks posed by the use of engineered nanomaterials (ENM), and secondly to implement procedures for the purpose of risk mitigation. These include establishing exposure control limits and controlling and monitoring exposure, including the accidental explosive or massive release of ENP into the environment. To this end, the release of ENP originating from specific nanopowders was simulated in a 31 m3 airtight chamber of controllable environment. Their loss and dispersion characteristics were studied under ventilated and unventilated conditions. The explosion characteristics of specific ENP in lean hybrid blends of nanoparticles with methane and air, were studied in a 23 L cylindrical combustion vessel providing the adjustment of isotropic turbulence induced by specially designed fans. The influence of ENP o...

Particle Emission and Exposure during Nanoparticle Synthesis in Research Laboratories

Annals of Occupational Hygiene, 2009

Real-time size, mass and number particle concentrations, and emission rates in university laboratories producing nanoparticles by scalable flame spray pyrolysis are quantified. Measurements were conducted in four laboratories using various technological set-ups and during production of particles of a range of compositions with differing physical-chemical properties, from NaCl salt, BiPO 4 , CaSO 4 , Bi 2 O 3 , insoluble TiO 2 , SiO 2 , and WO 3 to composites such as . Production time ranged from 0.25 to 400 min and yields from 0.33 to 183 g. Temporal and spatial analyses of the particle concentrations were performed indicating that elevated number concentrations in the workplace can occur. Airborne submicron number concentrations increased from background levels of 2100 up to 106 000 cm 23 during production, while the mass concentration ranged from a background of 0.009 to 0.463 mg m 23 . Maximum particle number emission rates amounted to 1.17 3 10 12 min 21 . The size distributions displayed concentration peaks mainly between 110 and 180 nm. However, changes in the operating conditions and the production of certain nanoparticles resulted in concentration peaks in the nanoparticle size range <100 nm. The effectiveness and limitations of current technology in assessing researchers' exposure to nanoparticles during production are examined, and further measures for workers' protection are proposed.