Effects of flammability characteristics of steam inerting to solution of acetone in water

Preventing accidental explosions of flammable liquid/gas mixtures is very important. As far as flammability characteristics are concerned, we simulated the effects of inert liquid/gas, which was filled with reactors, vessels, or closed space, employed in the chemical process industries. The inert liquid/gas (H₂O) weakened the oxygen concentration and reduced solvent vapor concentration in a 20-L-Apparatus. This study investigated the flammability characteristics of acetone/water solutions (100/0, 75/25, 50/50, and 25/75 vol.%) that are controlled at a temperature of 150°C and pressures of 101/202 kPa, respectively. The flammability parameters included flammability limits (LEL and UEL), maximum explosion pressure (P _max), maximum explosion pressure rise ((dP dt ⁻¹)_max), and vapor deflagration index (K _g). The results of a series of experimental tests showed that UEL, P _max, and K _g all decreased with steam rising under the experimental conditions. The results can be applied to process safety design/operation for identifying whether the inert liquid/gas (H₂O) content has any substantial effects in reducing the fire and explosion hazard of the solution of interest.     

Flammability characteristics studies on toluene and methanol mixtures with different vapor mixing ratios at 1 atm and 150°C

The flammability characteristics of chemical substances are very important for safety considerations in manufacturing processes. This study investigated the mixing of toluene and methanol mixtures with five vapor mixing ratios (100/0, 75/25, 50/50, 25/75 and 0/100 vol.%) at initial conditions of 1 atm and 150°C, and determined the flammability properties to identify their potential fire and explosion hazards. These safety-related parameters included lower explosion limit (LEL), upper explosion limit (UEL), maximum explosion overpressure (P _max) and rate of maximum explosion pressure rise ((dP/dt)_max); all of them were measured by a 20-L-Apparatus. In terms of flammability tests for this research, the experimental results indicated that when methanol was increased, which could induce a higher range of flammability, afterwards the situation could be triggered to a dangerous level, such as fire or explosion. Based on the above-mentioned, we could obtain a series of flammability properties and provide inherently safer design in related industrial processes for preventing serious fire and explosion accidents.     

Fire and explosion hazard evaluation for the acetone aqueous solutions

The prevention of fire and explosion is recognized as an imperative necessity that is a first priority in all operating management details of the chemical process industries. Based on significant research and original emphasis on loss control and disaster prevention, this study investigated the flammability characteristics, comprising the lower/upper explosion limit (LEL and UEL), maximum explosion overpressure (P _max), maximum rate of explosion pressure rise [(dP dt ⁻¹)_max], gas or vapor deflagration index (K _g), and explosion class (St class) of four acetone aqueous solutions [water vapor (steam)/acetone: 75/25, 50/50, 25/75, and 0/100 vol.%], and discussed the effect of inert steam (H₂O_(g)) on them. Interactive influences of various loading fuel concentrations and initial testing conditions of 150, 200 °C, and 101, 202 kPa on flammability characteristics were revealed via a 20-L-apparatus. Weighting analysis of the above influence factors was explored by employing the GM(h,N) grey system theory for rating their fire and explosion hazard degrees both specifically and quantitatively. The results indicated that the most important influence factor was the initial pressure that the manager or engineer in such a steam/acetone mixing system should consider to be well-controlled first. The second influence factor in GM(1,N) and GM(0,N) model was the initial temperature and steam/acetone mixing concentration, but the third influence factor was individual contrariwise. This study established a complete flammability hazard evaluation approach that is combined with an experimentally and theoretically feasible way for fire/explosion prevention and protection. The outcomes would be useful for positive decisions for safety assessment for the relevant practical plants or processes.     

Flammability properties analysis of methylphenol-carbonate in diphenylcarbonate production process

Diphenylcarbonate (DPC) has been regarded as a potential substitute material for highly toxic phosgene, reacting with bisphenol A (BPA) in a phosgene-free process to produce polycarbonate (PC). For synthesizing DPC, methylphenylcarbonate (MPC) was the critical intermediate with potential flammability in a transesterification reaction from dimethylcarbonate (DMC) and phenol. Under the National Fire Protection Association (NFPA) criterion, MPC is viewed as one sort of combustible liquid (Class IIIB). Once it fires or burns during storage, operation or transportation, it can cause a serious fire and explosion. However, researches are still scanty in mentioning the basic but crucial fire and explosion features of MPC to date. A sound background of material safety properties is essential for safe handling; in particular, flammability information is extremely crucial for a specific chemical during a unit operation to prevent any fire and explosion hazards. In this study, we investigated the explosion limits (LEL, UEL), maximum explosion pressure (P _max), maximum rate of explosion pressure rise ((dP/dt)_max), and gas or vapor explosion constant (K _g) of MPC, according to its practical operating conditions (1 atm, 250°C, 21 vol.% O₂) and by means of a 20 L vessel (20-L-Apparatus). By surveying and defining the experimental data through flammability tests, these basic but crucial safety-related parameters on flammability characteristics of MPC were proposed, so as to advance understanding and to avoid fire and explosion accidents for such relevant processes.     

Elevated pressure and temperature effects on flammability hazard assessment for acetone and water solutions

Flammable chemicals are frequently encountered in industrial processes. Under the safe operation basis and for fire/explosion danger prevention, it is imperative to recognize the flammability characteristics of these processes, especially under the working scenarios for elevated pressure and temperature. This study was conducted to investigate fire and explosion properties, including the explosion limits (LEL and UEL), maximum explosion overpressure (P _max), maximum rate of explosion pressure rise (dP/dt)_max, gas or vapor deflagration index (K _g) and explosion class (St) of various acetone/water solutions (100, 75, 50 and 25 vol.%) at higher initial pressure/temperature up to 2 atm and 200°C via a 20-L-Apparatus. We further discussed the safety-related parameters and fire/explosion damage degree variations in the above aqueous acetone within 1 atm and 150°C. The results offered a successful solution for evaluating the flammability hazard effect in such a relevant crucial process with elevated pressure and temperature.     

Flammability studies of benzene and methanol with different vapor mixing ratios under various initial conditions

This research investigated the influence of binary solutions of benzene and methanol for their vapor flammability characteristics. The different mixing ratios (100/0, 75/25, 50/50, 25/75 and 0/100 vol%) samples were injected into a 20-liter spherical explosion vessel under various initial temperatures (100, 150 and 200°C) to study their flammability behaviors. According to the experimental results, the flammability diagram of mixtures can be completely illustrated and combined with specific safety-related properties such as lower explosion limit (LEL), upper explosion limit (UEL), minimum oxygen concentration (MOC), maximum explosion overpressure (P_max), and gas or vapor deflagration index (K_g). The experimental results showed that the UEL, P_max and K_g all increased with the temperature, pressure and oxygen concentration, whereas there was no significant variation on the part of LEL. The results can provide specific information on fire and explosion hazards for related industries.     

Fire and explosion properties examinations of toluene–methanol mixtures approached to the minimum oxygen concentration

The minimum oxygen concentration (MOC) is an important safety parameter of safety for fire/explosion prevention of practical processes with fuel-air-inert mixtures. In this study, the critical fire and explosion properties stand for the explosion sensitivity (lower explosion limit (LEL), upper explosion limit (UEL)), explosion maximum indices (maximum explosion pressure (P _max), maximum rate of explosion pressure rise (dP dt ⁻¹)_max) and explosion damage degree (gas or vapor deflagration index (K _g)/St Class). These imperative parameters of various toluene/methanol mixing solvents (100/0, 75/25, 50/50, 25/75 and 0/100 vol.%) were experimentally determined within a closed spherical vessel of 20 L (20-L-Apparatus) at 101 kPa and 150 °C. Particularly, we discussed the variations both on the above characteristics and implied flammability hazard degree within different initial oxygen circumstances; the specific effects on toluene/methanol mixing solvents were to be clarified accompanied with reducing loading oxygen concentrations, gradually approaching up to the MOC in this present work. Finally, a triangle flammability diagram with the five toluene/methanol components in our testing arrangements and conditions was established for graphically indicating the dangerous fire/explosion hazard region. It has been confirmed that this study would be very useful in relevant industrial processes for a proactive loss prevention program. The experimentally derived outcomes are recommended for the inherently safer design (ISD) for forestalling any accidents from fires and explosions.     

Inert effects on the flammability characteristics of methanol by nitrogen or carbon dioxide

Knowledge of material safety properties is critical for safe handing in the chemical process industries, especially for flammable chemicals that might result in serious fires and explosions. This study investigated the flammability characteristics of methanol under working conditions during the process. The targeted fire and explosion properties, like explosion limits (UEL and LEL), vapor deflagration index (K _g), maximum explosion pressure (P _max), and maximum explosion pressure rise [(dP dt ⁻¹)_max], were deliberately obtained via a 20-L-Apparatus in 101 kPa (i.e., 760 mmHg/1 atm), 150 and 200 °C, along with various experimental arrangements containing nitrogen (N₂) or carbon dioxide (CO₂) as inert component. Particularly, this study discussed and elucidated the inert influence on the above safety-related parameters by two different inerting gases of N₂ and CO₂. The results indicated that adding an inert component to fuel–inert gas mixtures determined the decrease of explosion range and flammability hazard degree. The results also demonstrated that CO₂ possessed higher inerting capability than N₂ in this study.     

Preparation of Nicotinic Acid from Oxidation of 3-Picoline with Oxygen Under Catalysis of T（o-Cl）PPMn

The oxidation of 3-picoline to nicotinic acid took place efficiently in an ethanol solution with 02 as the oxidant under the catalysis of T（o-Cl）PPMn at 40--150 ℃ and 0.5--3.0 MPa oxygen pressure. The influences of temperature, oxygen pressure, reaction time, concentration of 3-picoline, concentration of sodium hydroxide, and concentration of T（o-Cl）PPMn catalyst, etc. on the production of nicotinic acid were investigated. The results show that T（o-Cl）PPMn presented excellent catalytic activity in the oxidation Of 3-pieoiine to nicotinic acid and the yield of nicotinic acid varied greatly with the reaction temperature, oxygen pressure, T（o-Cl）PPMn concentration, etc.     

Effects of cumene hydroperoxide on phenol and acetone manufacturing by DSC and VSP2

Cumene hydroperoxide (CHP) being catalyzed by acid is one of the crucial processes for producing phenol and acetone globally. However, it is thermally unstable to the runaway reaction readily. In this study, various concentrations of phenol and acetone were added into CHP for determination of thermal hazards. Differential scanning calorimetry (DSC) tests were used to obtain the parameters of exothermic behaviors under dynamic screening. The parameters included exothermic onset temperature (T ₀), heat of decomposition (ΔH _d), and exothermic peak temperature (T _p). Vent sizing package 2 (VSP2) was employed to receive the maximum pressure (P _max), the maximum temperature (T _max), the self-heating rate (dT/dt), maximum pressure rise rate ((dP/dt)_max), and adiabatic time to maximum rate ((TMR)_ad) under the worst case. Finally, a procedure for predicting thermal hazard data was developed. The results revealed that phenol and acetone sharply caused a exothermic reaction of CHP. As a result, phenol and acetone are important indicators that may cause a thermal hazard in the manufacturing process.     

Gossypol clathrates: Structure and thermal behavior of gossypol solvates with two picoline isomers

Gossypol forms stable solvates with 4- and 2-picolines at room temperature. The solvates are investigated by single crystal X-ray diffraction and thermal analysis. Solvate crystals of gossypol with 4-picoline (1) have the 1:3 composition (gossypol:4-picoline) and crystallize in the P2₁/c space group. This substance is isostructural to a trisolvate of gossypol with pyridine. Solvate crystals of gossypol with 2-picoline (2) have the 1:4 composition (gossypol:2-picoline) and crystallize in the P-1 space group. The unit cell parameters for the investigated structures are as follows: 1 monoclinic crystals, C₃₀H₃₀O₈·3C₆H₇N, a = 10.7530(1) ?, b = 20.7834(3) ?, c = 19.1166(2) ?, β = 95.537(1)°, V = 4252.32(9) ?³, M = 797.92, Z = 4, d _x = 1.246 g/cm³, and R = 0.0489 for 4102 reflections; 2 triclinic crystals, C₃₀H₃₀O₈·4C₆H₇N, a = 11.467(1) ? b = 14.962(2) ?, c = 15.570(3) ?, α = 75.62(1)°, β = 69.83(1)°, γ = 79.58(1)°, V = 2414.6(7) ?³, M = 891.04, Z = 2, d _x = 1.226 g/cm³, and R = 0.0528 for 3779 reflections. The results of the single crystal XRD and thermal analysis confirm that gossypol with 4-picoline forms a trisolvat, and a tetrasolvate with 2-picoline. The transition from 4-picoline to 2-picoline proves to change the type of the host-guest association from one-dimensional to zero-dimensional, i.e., to lead to a new crystal structure. Desolvation of compound 2 begins at a lower temperature than that for compound 1, which is explained by their different crystal structures. Keywords: gossypol, 4-picoline, 2-picoline, clathrate formation, crystal structure.     

Reactivity in the solid-state between ZnWO<Subscript>4</Subscript> and some rare-earth metal molybdates RE<Subscript>2</Subscript>MoO<Subscript>6</Subscript> (<Emphasis Type="Italic">RE</Emphasis>=Y,Sm, Eu,Gd, Dy,Ho, Er and Lu)

Organic peroxides (OPs) have caused many momentous explosions and runaway reactions, resulting from thermal instability, chemical pollutants, and even mechanical shock. In Taiwan, dicumyl peroxide (DCPO), due to its unstable reactive nature, has caused two thermal explosions and runaway reaction incidents in the manufacturing process. To evaluate thermal hazards of DCPO in a batch reactor, we studied thermokinetic parameters, such as heat of decomposition (†H _d), exothermic onset temperature (T ₀), maximum temperature rise ((dT/dt)_max), maximum pressure rise ((dP/dt)_max), self-heating rate (dT/dt), etc., via differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2).     

Thermal hazard evaluation for methyl ethyl ketone peroxide mixedwith inorganic acids

Methyl ethyl ketone peroxide (MEKPO) possesses complex structures which have caused many incidents involving fires or explosions by mixing with incompatible substances, external fires, and others. In this study, reactivities or incompatibilities of MEKPO with inorganic acids (HCl, HNO₃, H₃PO₄ and H₂SO₄) were assessed by differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). Parameters obtained by the above-mentioned devices could be readily employed to discuss the runaway reaction, such as onset temperature (T ₀), heat of reaction (ΔH _d), time to maximum rate (TMR), maximum self heat rate (dT/dt)_max, adiabatic temperature rise (ΔT _ad), maximum pressure of decomposition (P _max) and so on. Mixing MEKPO with hydrochloric acid resulted in the lowest T ₀ among inorganic acids. Nitric acid not only lowered the T ₀ but also delivered the highest heat releasing rate or self heat rate (dT/dt), which was concluded to be the worst case in terms of contamination hazards during storage or transportation of MEKPO.     

NMR and theoretical study on the interaction between diperoxovanadate and 3-picoline derivatives

To understand the substituent effects of 3-picoline derivatives on reaction equilibrium, the interactions between a series of 3-picoline-like ligands and [OV(O₂)₂(D₂O)]^?/[OV(O₂)₂(HOD)]^? in solution were explored by multinuclear (¹H, ¹³C, and ⁵¹V) magnetic resonance, COSY, and HSQC in 0.15 mol L^?1 NaCl ionic medium for mimicking physiological conditions. The relative reactivity among the 3-picoline derivatives is 3-methyl pyridine > nicotinate >nicotinamide > ethyl nicotinate. Competitive coordination results in the formation of a series of new six-coordinated peroxovanadate species [OV(O₂)₂L] ^{n ?} (L = 3-picoline derivatives, n = 1 or 2). Density functional calculations provide a reasonable explanation on the relative reactivity of the 3-picoline derivatives. Solvation effects play an important role in these reactions.     

Thermal runaway analyses for two organic peroxides with H2O and dry fire-extinguishing chemicals by DSC and VSP2

In recent years, organic peroxides, including methyl ethyl ketone peroxide (MEKPO) and cumene hydroperoxide (CHP), have often caused thermal runaway reactions, fires, and thermal explosions worldwide. Under normal circumstances, H₂O and dry fire-extinguishing chemicals are often employed to eliminate fire situations. We evaluated the thermal runaway reaction for MEKPO and CHP mixed with H₂O and dry fire-extinguishing chemicals by differential scanning calorimetry, and thermal runaway reaction for CHP mixed with dry fire-extinguishing chemicals by vent sizing package 2. The results showed that ABC dry chemical, BC dry chemical, and XBC dry chemical all caused the decomposition of MEKPO to occur at lower onset temperature and H₂O caused the ΔH _d of MEKPO to become higher. On the other hand, H₂O and XBC dry chemical induced the decomposition of CHP to occur at lower onset temperature as well as lower thermal explosion temperature. The maximum of self-heating rate ((dT/dt)_max) and the maximum pressure-rise rate ((dP/dt)_max) of CHP mixed with dry fire-extinguishing chemicals were measured lower than CHP alone. The results indicated that MEKPO and CHP are highly hazardous when mixed with H₂O and some dry fire-extinguishing chemicals. In view of loss prevention, the results can be useful references for fire fighters dealing with thermal upsets in chemical plants.     

IR multiphoton dissociation of CF3I. Pressure effect with inert and reactive gases

The IR multiphoton dissociation of CF₃I has been studied in the presence of isobutane and with isobutane and Ar and CO₂ as inert gases. The dependence of the reaction probability P(Φ) with fluence (ϕ) is confirmed. Modeling of the experimental results shows that for the energy transfer processes the average energy transferred per collision 〈†E〉_d varies with (ϕ).     

Synergistic fire safety improvement between oyster shell powder and ammonium polyphosphate in TPU composites

In this article, oyster shell powder (OSP) was used as fire safety agent with ammonium polyphosphate (APP) in thermoplastic polyurethane (TPU) composites. The synergistic fire safety improvement between OSP and APP was intensively investigated using limiting oxygen index (LOI), UL‐94, smoke density test (SDT), and cone calorimeter test (CCT). There is a good synergistic effect of reducing the fire hazards when OSP was used with APP in TPU. The peak heat release rate (pHRR) of the sample with 2.0‐wt% OSP and 8.0‐wt% APP decreased to 86.8 kW/m² from 175.7 kW/m² of the sample with only 10.0‐wt% APP. The SDT results showed that the luminous flux of sample OSP2/APP8 was up to 28.9% at the end of experiment with flame, which was much higher than that of pure TPU (1.5%). The thermal stability and thermal decomposition of TPU composites were characterized by thermogravimetric analysis/Fourier infrared spectrum analysis (TG‐IR). The result revealed the inert gasses (including CO₂ and water vapor) produced by the reaction between OSP and APP. A char formed on the surface of composites, hindered the flame spread, reduced the release of combustible gas, and restricted the precursor of smoke into combustion zone.     

Synthesis and characterization of 3-picoline adducts of bis(O,O′-ditolyl/dibenzyl/diphenyl dithiophosphato)cobalt(II) complexes: crystal structure of 3-picoline adducts Co{S2P(OC6H4Me-p)2}2(NC5H4Me-3)2

Bis(O,O′-ditolyl/dibenzyl/diphenyl dithiophosphato)cobalt(II) (1–5) with 3-picoline, Co{S₂P(OR)₂}₂(NC₅H₄Me-3)₂ (R?=?o-, m-, p-C₆H₄Me, CH₂Ph, Ph) have been synthesized by in situ reaction of 3-picoline and CoCl₂·6H₂O in aqueous medium followed by the addition of aqueous solution of NH₄S₂P(OR)₂. The single crystal structure of Co{S₂P(OC₆H₄Me-p)₂}₂(NC₅H₄Me-3)₂ shows that geometry around cobalt(II) is distorted octahedral with two 3-picoline molecules in trans positions. These Co(II) dithiophosphate complexes (1–5) have been characterized by elemental analyses, spectroscopic techniques (UV-Vis, IR), and magnetic moment measurements.     

Reactive incompatibility of DTBP mixed with two acid solutions

Organic peroxides are commonly employed as an initiator for polymerization, a source of free radicals, a hardener, and a linking agent. Due to its relatively weak oxygen-oxygen bond, di-tert butyl peroxide (DTBP) has been categorized as flammable type or Class III by the National Fire Protection Association (NFPA). The transport of dangerous goods (TDG) has published a warning against DTBP that it could potentially induce violent heat, explosion, fire and self-ignition under certain circumstances. DTBP has been recommended as an international standard sample for estimating the performance of several calorimeters, such as glass tube tests, differential scanning calorimetry (DSC), and vent sizing package 2 (VSP2). In this study, we measured the precise temperature changes and heat flow with the above-mentioned testing instruments. However, some runaway incidents caused by DTBP have demonstrated the reaction temperature could be as low as ambient temperature. The reactivity and the hazardous incompatibility with sulfuric acid (H₂SO₄) and hydrochloric acid (HCl) of DTBP have not been evident, and the runaway hazards involved in different processing conditions were clarified in this study by implementing the two calorimeters. Acid-catalyzed characteristics and reaction hazards of DTBP could be acquired, such as heat of decomposition (ΔH _d) and exothermic onset temperature (T ₀).     

Experimental Study of the Thermal Decomposition Properties of Binary Imidazole Ionic Liquid Mixtures

Ionic liquids (ILs) have a wide range of applications, owing to their negligible vapor pressure, high electrical conductivity, and low melting point. However, the thermal hazards of ILs and their mixtures are also non-negligible. In this study, the thermal hazards of various binary imidazolium ionic liquids (BIIL) mixtures were investigated. The effects of parent salt components and molar ratios on the thermal decomposition temperature (T_d) and flashpoint temperature (T_f) are investigated. It is found that both T_d and T_f increase as the proportion of highly thermally stable components in BIIL mixtures increases. Furthermore, the decomposition process of BIIL mixtures can be divided into two stages. For most molar ratios, the T_f of the BIIL mixtures is in the first stage of thermal decomposition. When the proportion of highly thermally stable components is relatively high, T_f is in the second stage of thermal decomposition. The flammability is attributed to the produced combustible gases during the thermal decomposition process. This work would be reasonably expected to provide some guidance for the safety design and application of IL mixtures for engineering.