Roberto Sanchirico

• Dr
• Researcher at Italian National Research Council

The shelf life of energetic materials (EMs) is directly associated with safety and functionality. Therefore, a priori knowledge of this parameter is essential. The standard approach for predicting the shelf life of EMs is tremendously time and money consuming. It involves massive accelerated aging tests at temperatures typically between 40 and 80 °...

A priori knowledge of the shelf life of energetic materials (EMs) is relevant due to its direct association with safety and functionality. This paper proposes a quick and reliable approach to predicting the shelf life of EMs whose thermal decomposition is an autocatalytic process once their failure threshold has been defined as a function of the li...

An unexpected promoting effect of KBr, used as a diluting salt, on the degradation of picric acid (PA) was observed during in situ diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy experiments performed here under accelerated ageing conditions—at 80 °C and under an inert or oxidative atmosphere. While the formation of potassium pi...

Safety parameters assessment is not sufficient to fully understand the flammable and explosive behaviour of a combustible dust and correctly manage potential risk. A correct evaluation requires the identification of flame propagation path as well as the limiting step controlling fire propagation, through evaluation of dimensionless numbers (Biot, D...

Against dust explosions, all the flammability and explosibility parameters must be evaluated following standard procedures using the 20 L and/or the 1 m³ vessel. Previous results comparing the dust dispersion in the 20 L sphere equipped with rebound or perforated annular nozzle showed that the initial turbulence level, the dust concentration, and t...

Featured Application This work will help to identify and assess the dust explosion risk related to biomasses intended for energetic purposes. Abstract The concern about global warming issues and their consequences is more relevant than ever, and the H2020 objectives promoted by the EU are oriented towards generating climate actions and sustainable...

Food and drink supply chains have significant environmental impacts due to their use of resources, emissions, and waste production. An efficient method to reduce this impact is the valorisation of biomass waste through energy recovery by using it as a source of heat. The European energy system faces several fundamental challenges being currently th...

There are at least two main requirements for repeatable and reliable measurements of flammability and explosibility parameters of dusts: a uniform dispersion of solid particles inside the test vessel and a homogeneous degree of turbulence. Measurements of these parameters are performed in spherical vessels (20 L sphere or 1 m 3 sphere). In several...

Several phenomena (e.g., initial turbulence level, overdriving, underdriving, etc.) affect the measurement of dust explosion parameters in the 20 L and 1 m³ standard test vessels. Estimating the role of each phenomenon is crucial to understand the discrepancies observed over the years between the data collected using these vessels. In this work, we...

In this work, the effect of spatial distribution and values of the turbulent kinetic energy on the pressure-time history and then on the explosion parameters (deflagration index and maximum pressure) was quantified in both the standard vessels (20 L and 1 m³). The turbulent kinetic energy maps were computed in both 20 L and 1 m³ vessels by means of...

According to standard procedures, flammability and explosion parameters for dusts and dust mixtures are evaluated in 20 L and/or 1 m³ vessels, with equivalent results provided a correct ignition delay time is used (60 ms in the 20 L vessel; 600 ms in the 1 m³ vessel). In this work, CFD simulations of flow field and dust concentration distribution i...

There are at least two main requirements for repeatable and reliable measurements of flammability and explosibility parameters of dusts: a uniform dispersion of solid particles inside the test vessel, and a homogeneous degree of turbulence. In several literature works, it has been shown that, in the standard 20 L sphere, the dust injection system g...

Understanding flame propagation mechanism and thermal behavior of flammable dusts is of crucial importance, since they strongly affect the flammability and explosion parameters. In a previous work, we found that the volatile point of anthraquinone/nicotinic acid mixtures can be lower than the one of the pure dusts, suggesting a synergistic effect....

In this work the flammable/explosive behavior of mixtures of flammable dusts is investigated. In particular, minimum ignition temperature, minimum ignition energy, maximum pressure and deflagration index have been measured at varying the relative content of dusts in the mixtures. The thermal behavior of these mixtures has been also studied by means...

In the work presented in this paper, the effect of initial pressure on the lower explosion limit (LEL) of the hybrid nicotinic acid/acetone mixture was investigated through standard explosion tests carried out in the 20 L sphere. From experimental results, the flammability diagram was built in the plane (concentration/minimum explosive concentratio...

In the work presented in this paper, the role of particle shape in turbulence generation, and dust feeding and dispersion in the standard 20 L explosion sphere has been investigated. To this end, CFD simulations were performed by taking into account only the effect of the shape factor on the drag coefficient, whereas the effect of the particle geom...

Emerging technologies and processes, such as nano and green technologies, sustainable processes, and additive manufacturing processes, have led to the development and handling of “novel” materials, which pose significant safety issues as they exhibit properties different from those of commonly used materials. The main differences are related to the...

A novel flammability parameter (Volatile Point, VP) of pure dusts, dust mixtures and hybrid mixtures is here measured and proposed as a key parameter to assess flammability. This parameter is defined as the temperature at which volatiles are produced generating a flammable vapor mixture, similarly to the Flash Point defined for flammable liquid sub...

Several tests that can be used to determine dust explosibility parameters have been presented in the technical and scientific literature to assess the characteristics of a dust sample. Some parameters are countable variables that can be defined by a numerical value (e.g. Pmax, kst), while others define a threshold above (or below) which an explosio...

Standard explosion tests were performed in the 20 l sphere to measure the minimum explosion concentration (MEC) of nicotinic acid in air at different initial pressures. CFD simulations were also run in order to gain insight into the experimental results particularly in terms of effects of initial pressure on turbulent flow field, and dust dispersio...

The effect of pressure on the flash point (FP) of various fuels (methanol, ethanol, acetone, ethyl acetate, n-hexane, n-octane, benzene, toluene) and their binary mixtures (ethanol-acetone, ethanol-n-octane, methanol-hexane) has been quantified. It has been found that the FP significantly decreases with decreasing pressure. In particular, in going...

In this work, the effects of intermolecular forces on Flash Point (FP) of various binary mixtures have been quantified through calculations taking into account their non-ideality. It has been shown that highly non-ideal mixtures with low-boiling azeotrope may have values of the FP lower than the lowest value of FP between those of the pure componen...

This article presents an analytical method for the calculation of the adiabatic time to maximum rate. The procedure is developed considering a thermal decomposition process described by a simple n-order kinetic and is based on the introduction of a special function that is possible by integrating analytically. The application of the method requires...

A three-dimensional CFD model was developed to simulate the turbulent flow field induced by dust feeding and the associated dust dispersion within the 20-L explosion vessel equipped with the perforated annular nozzle. The model was validated against experimental data for pressure and root mean square velocity.Simulation results have shown that the...

The thermal decomposition of 3,5-dinitro-4-methylbenzoic acid is studied by means of differential calorimetric techniques (DSC). Its autocatalytic behaviour has been highlighted and the decomposition process has been described considering the generalized expression of the Šesták-Berggren model. A new procedure for the optimization of the initiation...

The effect of the standard dust dispersers, rebound nozzle and annular nozzle, in the 20. L explosion vessel on the particle integrity has been quantified. Dispersion tests were run and measurements of the particle size before and after dispersion and of the elastic recovery of the materials were performed. The effect of the dispersion pressure was...

In the work presented in this paper, the explosion and flammability behavior of combustible dust mixtures was studied. Lycopodium, Nicotinic acid and Ascorbic acid were used as sample dusts. In the case of mixtures of two dusts, the minimum explosive concentration is reproduced well by a Le Chatelier's rule-like formula, whereas the minimum ignitio...

A CFD model was developed with the aim at simulating the turbulent flow field and associated dust dispersion in an agitated spherical explosion vessel. Simulations were performed in the presence of two counter-rotating fans and also after having switched-off the fans.Numerical results have shown that the dust mainly accumulates at the center of the...

With the terms “complex hybrid mixtures“, we mean mixtures made of two or more combustible dusts mixed with flammable gas or vapors in air (or another comburent).In this work, the flammability and explosion behavior of selected complex hybrid mixtures was studied. In particular, we investigated mixtures of nicotinic acid, lycopodium and methane. We...

Measurements of flammability and explosion parameters for dust/air mixtures require uniform dispersion of the dust cloud inside the test vessel. In a previous work, we showed that, in the standard 20 L sphere, the dust injection system does not allow generation of a uniform cloud, but rather high gradients of dust concentration are established. In...

Powder products are frequently meet as dust mixtures in industrial processes. However the effect of mixing combustible dusts on the flammability and explosion behaviour of their mixture is still unclear. This work dealing with the explosibility and flammability of dust mixtures made of Nicotinic acid and Lycopodium. Explosion tests on the 20-L expl...

A new method for the assessment of the kinetic triplet (pre-exponential factor, Activation energy, kinetic model) better describing a thermal decomposition process is presented. The approach is based on the processing of three DSC thermograms collected under dynamic conditions using different heating rates. It has been shown that two of this basic...

The article investigates the possibility of obtaining reliable information on the adiabatic behavior of thermally unstable substances based on the thermokinetic data collected by differential scanning calorimetric experiments. In particular, it is developed a novel numerical algorithm which allows the estimation of the adiabatic onset temperature....

A CFD model was developed with the aim at simulating the turbulent flow field induced by dust feeding and dispersion within the 20 L bomb, and the associated effects on the distribution of dust concentration. The model was validated con-sidering a set of data (pressure time histories and root mean square velocity) available in the literature. The t...

Prevention and mitigation measures for dust explosion are based on the knowledge of the thermokinetic parameters which characterise flammability such as Minimum Explosible Concentration, MEC, and explosion behaviour such as maximum explosion pressure, PMAX, and deflagration index, KSt. Measurements of these parameters are performed in spherical ves...

A major accident occurred in an Italian wool factory in 2001, culminating with a severe explosion, despite that wool is recognized as the most flame-resistant among the natural textile fibers. The analysis of this exceptional event suggests that, in addition to classical explosion parameters, three key phenomena related to the process jointly contr...

Explosions of hybrid mixtures of methane and nicotinic acid are investigated near the lower-flammability-limit conditions. The effect on the maximum pressure and deflagration index of the ignition energy and, then, of the ignition source in combination with the turbulence is analyzed. In correspondence of limit conditions for pure methane and pure...

The minimum number of thermoanalytical experiments that should be considered with the aim of performing a complete and reliable kinetic analysis when using semiempirical models is the problem of concern. It is shown by means of a series of numerical experiments that three differential scanning calorimetric (DSC) dynamic runs performed at different...

In a previous paper we showed that the theoretical evaluation of the thermo-kinetic parameters relevant to dust explosion (deflagration index; burning velocity and maximum pressure), may be performed by means of detailed simulations of the flame propagation of the volatiles produced during the pyrolysis/devolatilization step of the dust combustion....

The thermal decomposition of Fenitrothion [phosphorothioic acid O,O-diethyl O-(3-methyl-4-nitrophenyl) ester] was investigated. Results obtained by different scale calorimetric techniques show that the thermal decomposition of Fenitrothion involves two main steps. Intermediate and final thermal degradation products formed during isothermal and adia...

The explosion behaviour of heterogeneous/homogeneous fueleair (hybrid) mixtures is here analysed and compared to the explosion features of heterogeneous fueleair and homogeneous fueleair mixtures separately. Experiments are performed to measure the pressure history, deflagration index and flammability limits of nicotinic acid/acetone/air mixtures i...

Different calorimetric techniques coupled with chemical analyses and ecotoxicological bioassay led to the proposal of suitable protocol for the definition of a KPI (Key Process Index) useful to rank a compound in respect to the toxicological profile of its thermal decomposition products. Fenitrothion was used as example and showed to decompose thro...

The explosion features of nicotinic acid dust in atmosphere of methane and air at different concentrations of either dust or gaseous fuel are studied. Experimental measurements of the pressure history, deflagration index and flammability limits are performed by the standard 20. l Siwek bomb though adapted for such hybrid mixtures.Data show non line...

Deflagration index measurements have been performed in a 20 l sphere for methane/air and methane/nicotinic acid/air mixtures of different compositions at varying ignition delay time and, hence, turbulence level. We modelled the effect of the initial level of turbulence on the deflagration index values through formula for the turbulent burning veloc...

The explosion features of nicotinic acid dust in atmosphere of methane and air at different concentrations of either dust or gaseous fuel are studied. Experimental measurements of the pressure history, deflagration index and flammability limits are performed by the standard 20. l Siwek bomb though adapted for such hybrid mixtures.Data show non line...

Thermal decomposition process of cumene hydroperoxide (CHP) in cumene has been investigated by different researchers from chemical and kinetic point of view although its reactive characteristics have not yet been fully identified. The major discrepancy in the literature data is represented by different reaction nth-order and autocatalytic kinetics...

The problem of the formation of unwanted substances that can occur during thermal decomposition of chemicals is studied from a toxicological point of view. Two species, ethyl parathion (a widely used pesticide) and cumene hydroperoxide (an intermediate for the industrial production of phenol and acetone), are selected for this investigation. The ha...

Runaway phenomena and thermal explosions can originate during the nitration of salicylic acid by means of a nitric acid/acetic acid mixture when the thermal control is lost, mainly as a result of the formation and thermal decomposition of picric acid. The prediction of the behaviour of this system is thus of great importance in view of possible ind...

To better understand the batch production of 5-nitrosalicylic acid by means of the nitration of salicylic acid through the mixture nitric acid/acetic acid, the solubility of the two main mononitro derivatives of salicylic acid is investigated. For this purpose, the behavior of the two mononitro compounds in the ternary system organic/acetic acid/ni...

The nitration of salicylic acid by means of HNO 3 /AcOH is investigated, and the results are compared with those obtained using different nitrating systems: HNO 3 /H 2 SO 4 /H 2 O (mixed acid), HNO 3 /Ac 2 O/AcOH, aqueous HNO 3 (70% by weight) at 343 K. Little differences are found in terms of yield of the desired product (5-nitrosalicylic acid) am...

The nitration process of salicylic acid for the production of the important intermediate 5-nitrosalicylic acid is studied from thermokinetic and safety points of view. Investigations carried out by considering, as process deviations, the loss of the thermal control point out the possibility of runaway phenomena due to the occurrence of polynitratio...

The present work aims at assessing both thermodynamic and kinetic parameters of the esterification process of the (S)-carnitine, using calorimetric techniques. The use of the system acetic anhydride/nitric acid/acetic acid as esterifying agent and the explosive behaviour of nitric esters lead to safety considerations that have been investigated by...

SOMMARIO Il presente articolo descrive una ricerca, in corso di svolgimento presso il Dipartimento di Ingegneria Nucleare e Conversioni di Energia dell'Università di Roma "La Sapienza", su un sistema innovativo di refrigerazione di sicurezza da impiegare nell'industria di processo. Tale sistema è finalizzato ad asportare potenza termica da reattori...

The adoption of Ac2O/HNO3 mixtures for the nitration of organics or the preparation of nitric esters is not free from some risks of explosion. The behaviour of these mixtures at varying Ac2O/HNO3 molar ratios is studied by means of adiabatic and scanning calorimetry. A simplified kinetic model, based on two lumped reactions (one of which leads to t...

Advanced oxidation processes (O3/UV and O3/H2O2) have been adopted for the treatment of mineral oil-contaminated wastewater. All the experimental runs have been performed in a 0.2-l semicontinuous reactor (equipped with a nominal power of 17 W UV lamp for illuminated experiments). The results of this investigation show that the system O3/UV is capa...

Manganese-catalysed ozonation of glyoxalic acid in aqueous solutions has been investigated in the pH range 2.0–4.0. The addition of manganese ions (Mn(II) or Mn(IV)) to a glyoxalic acid–ozone system allows the substrate to be oxidized through a mechanism different from that reported for uncatalysed ozonation, as underlined by the formation of metha...

The thermal decomposition of ethyl parathion, an organophosphorus pesticide, has been studied by coupling calorimetric and chemical analysis. The decomposition process develops through two exothermic events with production of relevant amounts of uncondensible gases (final pressure 50bar in an ARC run). A simple autocatalytic kinetic model has been...

The thermal decomposition of dimethoate, an organophosphorus pesticide, has been studied with the aim at assessing the reaction kinetics, the energy released during the process and the decomposition products. Dimethoate shows a marked tendency to undergo thermal decomposition at temperature higher than 369 K. A moderate pressure increase has been r...

The thermal decomposition of 2-nitrobenzoic acid is investigated by means of adiabatic and quasi-isothermal calorimetry. The decomposition process develops according to zero order kinetics which gives substantial support to the intervention of vapour-phase reaction. The apparent activation energy of 144É8kJmol~1 is evaluated. Chemical analysis give...

4-Nitrobenzoic acid is produced through the oxidation of 4-nitrotoluene by means of diluted nitric acid. Since accidents have been reported for this process, the behaviour of the chemical system at varying operating conditions has been investigated by means of calorimetric techniques. The results evidenced the possible occurrence of the loss of the...