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 (Pmax), maximum rate of explosion pressure rise ((dP/dt)max), and gas or vapor explosion constant (Kg) 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.
Authors:J. Tseng, R. Chang, J. Horng, M. Chang, and C. Shu
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 (T0),
heat of reaction (ΔHd),
time to maximum rate (TMR), maximum self heat rate (dT/dt)max, adiabatic temperature
maximum pressure of decomposition (Pmax)
and so on.
Mixing MEKPO with hydrochloric acid resulted in the
lowest T0 among
inorganic acids. Nitric acid not only lowered the T0
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.
Convergence in Mallows distance is of particular interest when heavy-tailed distributions are considered. For 1≦α<2, it constitutes an alternative technique to derive central limit type theorems for non-Gaussian α-stable laws. In this note, we further explore the connection between Mallows distance and convergence in distribution. Conditions for their equivalence are presented.
In bread making the wheat dough undergoes some degree of deformation in each step of the process. It is generally accepted that the baking properties of wheat flour dough are mainly due to the viscoelasticity of the gluten protein. Measurement of the rheological properties of dough gives valuable information concerning the quality of the wheat flour, the machining properties of the dough and the textural characteristics of the finished products. This technique uses a new apparatus (wheat gluten quality analyser&WGQA, C HANG, 1994) especially developed to evaluate the rheological properties of gluten by measuring the following parameters: resistance to extension (newton), extensibility (mm) and energy (joule). The test realized with the apparatus WGQA was carried out on wheat gluten isolated according to the A.A.C.C. (1995) method. Results obtained using the new technique showed high levels of correlation for maximum resistance to extension (R 2 =0.9018) and energy (R 2 =0.8824) between WGQA and standardized parameters obtained from Brabender Extensograph.
A TiO2/monazite photocatalyst was prepared by embedding TiO2 nanoparticles into a monazite substrate surface. TiCl4 hydrolysis/citric acid chelating procedure under acidic conditions were used to synthesize the nanophase TiO2 particles. The anatase TiO2/monazite photocatalyst surface area, morphology, crystalline and elemental concentrations were characterized using Brunauer-Emmett-Teller
(BET) method, scanning electron microscopy (SEM), X-ray diffraction (XRD), and inductively coupled plasma-atomic emission
spectrometry (ICP-AES). Monazite contains a large amount of Ce-, La-, Nd- and Th-PO4 compounds; it has been known as a natural mineral material with minor radioactivity. TiO2-CeO2 composite is a kind of radiation sensitive photocatalyst in which the radiations of thorium nuclides give energy to trigger
TiO2 and cerium ions which play an energy absorber with charge separator. The result showed that methylene blue and phenol were
spontaneously photocatalytic decomposed by TiO2/monazite composite even in a dark environment. A synergistic effect was also examined with applied exterior UV or 60Co irradiation. A hybrid mechanism is proposed; according by the radioluminescence (RL) from excited Ce ion by γ-radiation
soliciting CeO2/TiO2 heterojunction (HJ). This seems to be a possible mechanism to explain this self-activated photo-catalytic behavior.
Authors:Y. Chang, J. Lee, S. Wu, C. Chen, and C. Shu
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 (Pmax), maximum rate of explosion pressure rise (dP/dt)max, gas or vapor deflagration index (Kg) 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.
Authors:C. Chang, Y. Chou, J. Tseng, M. Liu, and C. Shu
Many concerns over unsafe or unknown properties of multi-walled carbon nanotubes (MWNTs) have been raised. The thermal characteristics
regarding stability would represent potential hazards during the production or utilization stage and could be determined by
calorimetric tests for various thermokinetic parameters. Differential scanning calorimetry (DSC) was employed to evaluate
the thermokinetic parameters for MWNTs at various compositions.
Thermoanalytical curves showed that the average heat of decomposition (ΔHd) of the MWNTs samples in a manufacturing process was about 31,723 J g−1, by identifying them as an inherently hazardous material. In this study, significant thermal analysis appeared in the presence
of sulfuric acid (H2SO4). From the DSC experiments, the purification process of MWNTs could induce an unexpected reaction in the condition of batch
addition with reactants of H2SO4. The results can be applied for designing emergency relief system and emergency rescue strategies during a perturbed situation
Authors:C. Lin, Y. Chang, J. Lee, S. Lin, and C. Shu
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 (Pmax), maximum explosion pressure rise ((dP dt−1)max), and vapor deflagration index (Kg). The results of a series of experimental tests showed that UEL, Pmax, and Kg 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.
Authors:C.-C. Chiang, J.-C. Lee, Y.-M. Chang, C.-F. Chuang, and C.-M. Shu
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 (Kg), maximum explosion pressure (Pmax), 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.
Authors:Y.-M. Chang, J.-C. Lee, C.-C. Chen, and C.-M. Shu
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
(Pmax), maximum rate of explosion pressure rise (dP dt−1)max) and explosion damage degree (gas or vapor deflagration index (Kg)/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.