Fire hazard evaluation of activated carbons Lei, Qingqing; Xie, Qiyuan; Ding, Yanwei
Journal of thermal analysis and calorimetry,
2020/1, Volume:
139, Issue:
1
Journal Article
Peer reviewed
Activated carbons are widely used in the iodine adsorbers in nuclear plants, but little information about their combustibility is available for fire engineers. Series of TGA experiments were ...conducted for activated carbons, charcoal and XPS foam. The results show that the activated carbons oxidize strongly in air atmosphere but little in N
2
atmosphere. The calculated activation energies of the wood AC, anthracite AC and coconut shell AC are, respectively, 100.56, 96.34 and 91.00 kJ mol
−1
, which are larger than that of the XPS foam, 55.95 kJ mol
−1
. However, the calculated activation energies of impregnated coconut shell activated carbon is 48.60 kJ mol
−1
, which is smaller than that of XPS foam. A new parameter,
A
12
, is introduced to describe the amount of evaporative mass fraction during the fast pyrolysis stage. Additionally, the (
T
p
, DTG
p
) map and quarter division method is introduced to compare fire hazard of different materials. Finally, a quantitative fire hazard evaluation model is developed based on four important parameters:
E
, DTG
p
,
T
p
and
A
12
. The calculated Relative Fire Safety Factors by this model for wood AC, anthracite AC, coconut shell AC, impregnated coconut shell activated carbon, charcoal and XPS foam are 1.49, 1.91, 1.51, 1.37 and 1.0, respectively.
Lignocellulosic biomass is one of the potential sources for biofuel production. Coconut husk, one of the abundant lignocellulosic biomass in Indonesia, can be explored for such a process. This work ...evaluated compositions of raw and pretreated coconut husk powder using modeling and computation of thermogravimetry analysis data. Lignocellulose compositions and distributed activation energy model employing kinetic parameters were successfully obtained with the fit quality values of 0.1–0.35 %, and R-squared values (R2) equal 1. By this method, raw coconut husk powder was found to contain 30 % hemicellulose, 38.86 % cellulose, and 34.96 % lignin. The mean activation energy (E0) was 141–163, 173–181, and 200–230 kJ/mol for hemicellulose, cellulose, and lignin respectively. Meanwhile, the standard deviation activation energy (σ) was 4.8–7.5, 1.76–3.75, and 19–28 kJ/mol for hemicellulose, cellulose, and lignin respectively. The pre-exponential factor (A) values ranged from 1.20 × 1011 to 5.00 × 1013 s−1 where those of hemicellulose, cellulose, and lignin, respectively appeared in ascending order.
Display omitted
•Thermogravimetry data modeling for raw and pretreated coconut husk compositions•DAEM-based kinetic data fitting resulted in R2 = 1 and fit quality of <0.5 %.•Mean activation energy ranged from 141 to 230 kJ/mol for 3 lignocellulosic components.•Pretreated coconut husk powder samples showed higher DTG Peak temperature.
A plastic packaging residue provided by a central Italy recycling facility was the subject of study of the present paper. The aim is to propose the valorization of plastic film residue (PFR) through ...a pyrolysis process. The PFR was thermo-chemically characterized through heating value, proximate and ultimate analysis. Fourier transformed infrared measurements have shown that PFR is constituted by 92–95 mass% of polyethylene (PE) film, around 5 mass% of PP, polystyrene (PS) < 1 mass%, PET < 1 mass% and traces of foreign materials. The extremely high percentage (98.7 mass%) of volatile matter and the low content of ash (2.1 mass%), humidity (0.6 mass%) and chlorine (0.1 mass%) make PFR an optimum candidate as load of a pyrolytic reactor. Thermogravimetry (TG) experiments were carried out at five different heating rates (2, 5, 7, 10, 12 K min
−1
) to determine the kinetic parameters of pyrolysis (activation energy
E
, pre-exponential factor
A
and the reaction model). No significant variation of activation energy, calculated by an integral isoconversional method proposed by Vyazovkin, is observed with increasing the degree of conversion. An average value of 264 ± 5 kJ mol
−1
was estimated. Then, the Coats–Redfern method and the compensation effect were used to determine the ln
A
versus
α
data (being 41.9 the average value within the 0.25 <
α
< 0.85 range) and the reaction mechanism (R2 contracting cylinder model). Furthermore, the minimum energy required to pyrolyze 1 kg of PFR, about 2.27 MJ, was estimated by differential scanning calorimetry. It corresponds to about 5.5% of the exploitable energy of the input material.
The aim of the present study is to explore the physicochemical characteristics and pyrolysis kinetics of Parthenium Hysterophorus (PH). The physicochemical characteristics such as proximate and ...ultimate composition, lignocellulosic composition, heating value, and Fourier transform infrared spectroscopy (FTIR) of PH were carried out. Pyrolysis experiments were performed by thermogravimetric analysis under dynamic/non-isothermal conditions at three heating rates of 10°C, 20°C, and 30°C/min. Thermal analysis of PH confirms that the major mass loss occurs in the temperature range of 200°C to 500°C. Model free Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Kissinger methods were employed to compute the activation energy using thermogravimetric analysis data. The pre-exponential factors were also determined by Coats-Redfern method. The value of activation energy evaluated by Kissinger method was 135.85 kJ/mol, while the mean activation energy by KAS and FWO methods was 155.75 and 163.17 kJ/mol, respectively. Result showed that the activation energy varies with the degree of conversion. The results of this study suggest that PH has potential to use as a pyrolysis feedstock.
Pyrolysis behavior and kinetic properties of sawdust with the heating rates (
β
) of 5, 10, 15 and 20 °C min
−1
in nitrogen atmosphere were analyzed by using a thermogravimetric analyzer. The results ...showed that organics of sawdust mainly decomposed at 250–400 °C, and greater heating rate can move the peak of differential thermogravimetric curves toward higher temperature. Two iso-conversional methods, Flynn–Wall–Ozawa (FWO) method and Kissinger–Akahira–Sunose (KAS) method, were employed to analyze the non-isothermal pyrolysis kinetics of sawdust, and the range of apparent activation energies for sawdust pyrolysis is between 101.53 and 114.83 kJ mol
−1
using FWO method and is between 95.94 and 114.87 kJ mol
−1
using KAS method. Error limit from heating rate was first proposed to examine the reliability of two iso-conversional methods, and the error from heating rate cannot exceed the range of ±20 kJ mol
−1
in this study. Overall, these results suggested that the experimental results and kinetic parameters provided useful information for the design of pyrolytic processing system using sawdust as feedstock, and error limits demonstrated the precision of these obtained apparent activation energies.
The thermal degradation behavior and pyrolysis kinetic models of wood flour (WF)/PVC composites before and after adding chitosan were studied using thermogravimetry (TGA) and nine common kinetic ...model functions (f(α)). The results indicated that the thermal degradation temperature of WF/PVC composites was delayed to a higher value after adding chitosan. The first-order reaction order (L1) model and second-order reaction order (L2) model were found to be the best reaction order functions for the description of mass loss kinetics of WF/PVC without chitosan during the first and second stages. Two L2 models were suitable for both degradation stages of WF/CS/PVC. Activation energy (E) and frequency factor (A) for WF/PVC and WF/CS/PVC corresponded to 26.05 kJ·mol-1, 4.08×103 s-1, and 40.89 kJ·mol-1, 2.11×1010 s-1 at the first degradation stage, respectively, and 97.83 kJ·mol-1, 1.11×107 s-1 and 92.88 kJ·mol-1, 1.56×1011 s-1 at the second degradation stage.
There is an increasing concern with the environmental problems associated with the increasing CO
2, NO
x
and SO
x
emissions resulting from the rising use of fossil fuels. Renewable energy, mainly ...biomass, can contribute to reduce the fossil fuels consumption. Biomass is a renewable resource with a widespread world distribution. Tomato processing industry produces a high amount of biomass residue (peel and seeds) that could be used for thermal energy and electricity. A characterization and thermogravimetric study has been carried out. The residue has a high HHV and volatile content, and a low ash, and S contents. A kinetic model has been developed based on the degradation of hemicellulose, cellulose, lignin and oil that describe the pyrolysis of peel, seeds and peel and seeds residues.
Pyrolysis of virgin polyethylene plastics was studied in order to produce hydrocarbon liquid fuel. The pyrolysis process carried out for low and high-density polyethylene plastics in open system ...batch reactor in temperature range of 370 to 450°C.
Thermo-gravimetric analysis of the virgin plastics showed that the degradation ranges were between 326 and 495 °C. The results showed that the optimum temperature range of pyrolysis of polyethylene plastics that gives highest liquid yield (with specific gravity between 0.7844 and 0.7865) was 390 to 410 °C with reaction time of about 35 minutes. Fourier Transform Infrared spectroscopy gave a quite evidence that the produced hydrocarbon liquid fuel consisted mainly alkanes and the x-ray diffraction showed no sulfur in the produced hydrocarbon liquids.
In this study, the changes on physicochemical characteristics of pretreated and digested smooth cordgrass were investigated by the composition, X-ray, FTIR and
13C NMR, and TG analyses. Simultaneous ...lime treatment and dry digestion could be successfully carried out in leaching bed reactor at thermophilic condition with highest breakage of lignocellulose and higher biogas yield. Comparing with mesophilic condition, thermophilic condition brought a greater change of lignocellulosic structure, thus making holocellulose more accessible to anaerobic bacteria and benefiting to biogas production. The removal of lignin and hemicellulose at pretreatment phase was shown by the cleavage of ester linkage or carbonyl groups and the reducing intensity of lignin from FTIR and
13C NMR spectra analysis. The removal of polysaccharide mainly happened at digestion phase, as shown by the results of composition, FTIR and
13C NMR analysis. The crystalline index obviously decreased at pretreatment and digestion phases, as indicated by the intensity change of hydrogen bonding. The results of TG analysis showed that pretreatment and digestion had an obvious impact on the distribution of volatile matter, rate of weight loss and kinetic parameters of pyrolysis.
Pyrolysis kinetics of rubber glove with the heating rates (
β
) of 5, 10, 20 and 40 °C min
−1
were investigated by thermogravimetric analyzer from 100 to 1000 °C in nitrogen atmosphere. The results ...indicate that, during pyrolysis processes of rubber glove the peak of differential themogravimetry curves move toward higher temperature with the increase of heating rate and the change of temperature is approximately 40 °C from 5 to 40 °C min
−1
. Meanwhile, three iso-conversional methods (Kissinger’s method, Doyle’s approximation and Flynn–Wall–Ozawa method) are used for analysing the non-isothermal pyrolysis kinetic of rubber glove. It is found that the difference of the apparent activation energies obtained by the three iso-conversional methods is no more than 21 kJ mol
−1
and the overall trends are very similar. The range of apparent activation energies for rubber glove pyrolysis is between 103.88 and 184.33 kJ mol
−1
.
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