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This study examined the torrefaction performance of Jatropha-seed residue after mechanical screw-press extraction of oil (denoted as JME) at fixed torrefaction temperature (Tr) of 533, 553 and 573 K in the torrefaction time (tr) range of 10–60 min. The characteristics results of torrefied JME (JMET) indicated that the mass yield decreases while dry-basis high heating value (HHD) increases with increasing Tr and tr. At tr = 20 min or longer and Tr of 533–573 K, the HHD of obtained JMET is suitable for B1/B2/D Taiwan power industry fuel requirement. In addition, the H/C and O/C atomic ratios of JMET are better (i.e., lower) than those of torrefied wood and close to those of lignite and sub-bituminous coal. The satisfactory energy densification (ED) of about 1.3 can be achieved for Case 1 at higher Tr of 573 K and shorter tr of 30 min with log severity factor (logSF) of 7.37 or Case 2 at lower Tr of 553 K and longer tr of 50 min with logSF of 7.00. The results indicated that Case 2 exhibits a lower value of SF than Case 1 at the same level of satisfactory ED, which is more beneficial for the torrefaction of JME.

In this study, waste bamboo chopsticks (WBC) were upgraded as solid bio-fuel by torrefaction using a tubular furnace with nitrogen as carrier gas. In order to fulfill the quality specifications of coal and industrial wood pellets, the effects of temperature and time of torrefaction on proximate and ultimate compositions and its dry-basis heating value (H HD ) were studied and elucidated. The results showed that the mass yield of WBC is 69% at 563 K and 40 min, while H HD of WBC is increased from 19.31 to 23.04 MJ kg −1 with an energy densification factor of 1.19, which satisfy the specification of quality D of Taiwan Power Co. and I3 industrial quality of Initiative Wood Pellets Buyers. Further, the torrefied WBC (WBC T ) pellets become convenient to store, transport and processing and hard to be rotten because of the modification of surface hydrophobicity. The ash content of WBC T is only 2.19 wt.% in wet basis, which is beneficial in practical boiler. Further, the energies needed for drying, heating and torrefaction is 2.31 MJ for processing 1 kg WBC with CO 2 emission of 0.339 kg. Therefore, WBC T would be practical alternative as solid bio-fuel for cofiring with coal.

In this study, biomass of rice straw (RS) and wood (WD) and their torrefied biomass (RST and WDT) were used as solid biofuel (SBF) for co-firing individually with coal in a commercial continuous chain-grate steam boiler system, which was conducted at fixed input rate of heating value of mixture of SBF and coal and at fixed airflow rate. The effects of key system parameters on the gaseous and particulate pollutions and ash were examined. These include SBF type and blending ratio (RBL) of biomass (i.e., SBF) in the mixture of coal and biomass based on heating values for co-firing.The results indicated that wood, which possesses high heating value while less amount of ash, is more suitable for co-firing with coal than rice straw. Torrefaction can increase the heating value of biomass and homogenize its property, being beneficial to co-firing. Also, torrefaction can decompose the hydroxyl group of biomass, which makes biomass tending to possess hydrophobicity. This, in turn, helps the storage and transportation of biomass. Generally, adding the RS (with RBL = 5-10%), WD (2-15%), RST (2-10%) and WDT (2-20%), respectively, with coal decreases the emissions of NOx and SO2, but increases that of CO (except RST). The emission of HCl is little. The addition of biomass also increases the emission of fine particulate matters (PM) especially PM2.5 in the flue gases, raising PM2.5/PM100 from 34.87 to 78.35 wt.% (Case 50%WDT). These emissions for the Cases tested satisfy with Taiwanese emission standards of stationary sources which set limitations of NOx, SO2, CO and HCl < 350, 300, 2000 and 80 ppmv, while PM < 50 mg/m3, respectively. The results support the use of RS, WD, RST and WDT for co-firing with coal.Implications: This study examined the suitability of using solid bio-fuels to co-fire with coal in an industrial chain-grate steam boiler system with a capacity of 100 kW, in order to achieve carbon-free emissions. Both biomass and torrefied biomass of solid bio-fuel were tested. The findings would be useful for proper design and rational operation of solid bio-fuel/coal co-firing combustion matching the appeal of sustainable material management and circular economy of biomass, and of adaptation of global warming induced by greenhouse gases. It also provides information for policy-makers to promote the co-firing application of biomass and related bio-waste materials.

In this study, vinyl chloride (VC), the primary material for manufacturing polyvinyl chloride (PVC), is decomposed via catalytic oxidation (C-OX) using Pt/γ-Al2O3 catalyst. The effects of related major factors such as reaction temperature (T) and gas hourly space velocity on the conversion of VC (X) were examined. The values of T for achieving conversions of 50% and 90% are 504 and 580 K with C-OX, respectively, whereas those without Pt/γ-Al2O3 (i.e., thermal oxidation, T-OX) are 900 and 983 K, respectively, thus indicating that C-OX significantly reduces T for effective oxidation of VC to form CO2, HCl, and Cl2 when compared with T-OX. The mineralizations of carbon in VC to form CO2 are 75.5% and 38% for C-OX and T-OX, respectively, at 90% X. The conversions of chlorine atom in 1,2-dichloroenane (DCEA) to Cl in HCl and Cl2 are approximately 42% and 50.8% for C-OX and T-OX, respectively, at 90% X. These results indicate that the Pt/γ-Al2O3 catalyst exhibits remarkable performance for the mineralizations to form CO2 even though a proportion of chlorine atoms are adsorbed on the Pt surface. The Eley-Rideal model can be used to describe the experimental results, thus yielding activation energy and frequency factor values of 49.0 kJ mol(-1) and 1.77 × 10(6) s(-1), respectively. The obtained information and kinetic parameters are useful for the rational design and operation of C-OX process for the abatement of VC.

The effect of oxygen on the thermal degradation of rice straw was investigated with a thermal gravimetric analysis (TGA) reaction system. The TGA curves indicated two sharp mass changes during the process and the reaction could be simplified as occurring in two stages. Oxygen speeds up the thermal degradation of intermediates. A kinetic model was proposed and its corresponding parameters such as activation energies, pre-exponential factors, and reaction orders were determined through experiments conducted in nitrogen gas (N2), 10% oxygen gas (O2), and air at the heating rates of 2, 5, and 10 K/min. The experimental data agreed well with those predicted by the proposed model, which validated the applicability of this model to the design of agricultural waste processing systems.

Although the main purpose of the torrefaction of biomass is to produce high quality solid bio-fuel, the by-products, including liquid and gas products, are worth investigating to know their effects on the environment and the reusable possibility. Consequently, after torrefying waste bamboo chopsticks (WBCs) for producing solid bio-fuel, the liquid and gas products were examined in this study. The torrefaction target was set to produce torrefied waste bamboo chopsticks (WBCT) retaining about 70 wt %. A proper torrefaction temperature (Tr) and torrefaction time (tr) were found at 563 K and 40 min, respectively, for carrying out the torrefaction in a tubular furnace with carrier nitrogen. These conditions gave a solid yield (YS) of 69 wt % of WBCT relative to the original WBC, and 31 wt % of by-products were produced. The liquid products were composed of water as high as 62 wt %, along with some organic acids. Some medicine components were also found in the liquid products, representing potential medicine applications. During torrefaction, CO, NOx, SO2, and CO2 emissions were largely discharged from 10 to 20 min of torrefaction time. O2, CO2, and H2O are the major compounds in the total gas products collected. Some combustible gases of C1 to C6 hydrocarbons were also produced. Moreover, the gas volume balances were computed and evaluated. The information obtained in this study is useful for the proper design, operation, pollution control, and utilization of the products.

A radio-frequency-powered atmospheric pressure plasma jet (APPJ) was produced in ambient air assisted by Ar carried gas for the decomposition of binary mixture of naphthalene (Nap) and n-butanol without and with Pt/Al2O3 catalyst. The mixed feed gas streams of Nap/n-butanol were used to simulate the background of vapor released from the source solution of Nap, such as gasoline and some industrial flue gases. The effects of some major system parameters such as input power, plasma energy density ( E ¯ ) and space velocity (SV) of catalyst on the plateau temperature (TP) of reactor and conversions of Nap (XNap) and n-butanol (Xn-b) were studied and elucidated. The results show that the effectiveness of the catalytic APPJ (CAPPJ) is evident as indicated by the increase of XNap and Xn-b and the rate constant. At E ¯ = 3.75 kJ/L without catalyst, the values of XNap and Xn-b are 30 and 19%, respectively. In the presence of Pt/Al2O3 catalyst with SV = 17,400 1/h, XNap and Xn-b can reach as high as 99%. Note that the values of TP were 580 and 480 K without and with Pt/Al2O3 catalyst at SV = 17,400 1/h and E ¯ = 3.75 kJ/L . The proposed kinetic models describe the relationships of XNap and Xn-b with the major parameters and reaction order of −1.5 and 1 for the APPJ and CAPPJ degradation of binary mixture of Nap and n-butanol, respectively, showing good agreement with the experimental data. The information obtained is useful for operation, design, and analysis of plasma devices.

This study investigates the application of a radio-frequency-powered plasma with a Pt/γ-Al2O3 catalyst to decompose the chlorinated volatile organic compound of vinyl chloride (VC) in air. The use of an atmospheric-pressure plasma jet is explored as an innovative technology for the treatment of VC. The effects of some major system parameters such as input power (PWI), plasma energy density, initial concentration of VC (C0), and space velocity (SV) of the catalyst on the plateau temperature (TP) of a reactor and conversions of VC (XVC) are studied and elucidated. The results show that the effectiveness of the plasma-assisted catalysis is evident as indicated by the increase of XVC and the rate constant. At a PWI of 250 W without a catalyst, the values of XVC were 14% and 5.4% for C0 = 200 and 450 ppmv, respectively. In the presence of the Pt/γ-Al2O3 catalyst with an SV of 17 400 h-1, the values of XVC for C0 = 200 and 450 ppmv increased to 49% and 39%, respectively. Note that the values of TP were 550 K and 430 K without and with the Pt/γ-Al2O3 catalyst at an SV of 17 400 h-1 and a PWI of 250 W. The proposed kinetic models describe the relationships of C/C0 with the major parameters for the plasma and plasma-assisted catalytic degradation of VC, showing good agreement with the experimental data. The information obtained is useful for the operation, design, and analysis of plasma devices.

The effects of oxygen on the pyrolysis of rice husk were investigated with a thermal gravimetric analysis (TGA) reaction system. Pyrolysis experiments of rice husk were carried out in N 2 , 10% O 2 , and air at the heating rates of 2, 5, and 10 K/min. The TGA curves indicated two principal reactions, distinguished by significant and distinct mass changes over the experimental range. Oxygen enhanced the pyrolysis reactions of intermediates, which was produced from the first stage reaction of rice husk. A simple kinetic model was proposed for the pyrolysis of rice husk in different oxygen concentrations. The corresponding activation energies, preexponential factors, and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed kinetic model.

Oil sludge is one of the major industrial wastes that needs to be treated for the refinery or petrochemical industry. Efforts have been made to convert the oil sludge into available resources such as lower molecular weight organic compounds and carbonaceous residues. In this study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in northern Taiwan is used as the raw material of thermal treatment using oxygen-containing gas. The treatment of oil sludge is conducted by the use of carrier gas with different concentrations of oxygen (4.83, 8.62, 12.35, and 20.95 vol % O2) in the temperature range of 380−1123 K and at various constant heating rates of 5.2, 12.8, and 21.8 K/min. The significant reactions occur in the range 415−931 K. Below a temperature of 613 K, pyrolysis reactions are predominant. Including the pyrolysis reactions, the overall oxidative thermal decomposition of oil sludge can be adequately described by a five-parallel-reaction model. The activation energ...

The effects of oxygen on the pyrolysis of tetra pack, a principal component of municipal solid wastes in Taiwan, were investigated with a thermal gravimetric analysis ~TGA! reaction system. The pyrolysis experiments of tetra pack were carried out in four different oxygen concentrations (CO2 , 5.37, 10.40, 14.82, and 20.95%! at the heating rates of 5.25, 10.36, and 15.06 K/min. The TGA curves indicated two principal reactions, distinguished by significant and distinct mass changes over the experimental range. Oxygen enhanced the pyrolysis reaction of tetra pack. A kinetic model was proposed for the pyrolysis of the tetra pack in an oxygen environment. The corresponding activation energies, preexponential factors, and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed kinetic model. DOI: 10.1061/~ASCE!0733-9372~2003!129:4~382! CE Database subject headings: Pyrolysis; Kinetics; Oxygen; Solid wastes.

Waste newspaper, one of the principal waste papers in Taiwan, was pyrolyzed with a thermogravimetric analysis (TGA) reaction system. The pyrolysis experiments were carried out in nitrogen environment at a constant heating rate of 5 K min −1 . The pyrolysis products and the residues were collected and analyzed by gas chromatography and elemental analyzer, respectively. The major products investigated included non-hydrocarbons (H 2 , CO, CO 2 , and H 2 O) and hydrocarbons (C 1–3 , C 4 , C 5 , C 6 , 1-ring, C 10–12 , levoglucosan, C 13–15 , and C 16–18 ). The cumulated masses and the instantaneous concentrations of pyrolysis products were obtained under the experimental conditions. The estimation of the mass of tar, yielded at various pyrolysis temperatures, was also made. The results of this study might be useful for the design of pyrolysis process as well as for determining the pyrolysis mechanisms of the newspaper.

Glycolysis of flexible polyurethane (PU) was investigated to provide useful data for the recycling of waste cars. The glycolysis experiments were performed under atmospheric pressure and isothermal condition (220 °C). Diethylene glycol (DEG) and potassium acetate (KAc) were used as solvent and catalyst, respectively. The properties of glycolysis products were determined by analyzing the hydroxyl value, weight average molecular weight ( M w ), viscosity, and the conversion (X) of the –NCOO– functional group in PU. The results indicate that the adequate concentrations of DEG and KAc are about 150 and 1% of the mass of the PU and an adequate reaction time is 90 min. Purification experiments on the glycolysis products were carried out in a stirred flask with a shell and tube condenser. The distilled materials were collected at the gas-phase temperature ranges of 290 °C. The polyol-containing products are mostly in the temperature range of 245–260 °C. The recovery of polyol-containing products can be achieved by the distillation of glycolysis products.

Uncoated printing and writing paper, one of the principal waste papers in Taiwan, was pyrolyzed with a thermogravimetric analysis (TGA) reaction system. The pyrolysis experiments were carried out in nitrogen environment at a constant heating rate of 5 K min −1 . The gaseous products and the residues were collected at room temperature (300 K) and analyzed by gas chromatography (GC) and elemental analyzer, respectively. The major gaseous products investigated included non-hydrocarbons (H 2 , CO, CO 2 , and H 2 O) and hydrocarbons (C 1–3 , C 4 , C 5 , C 6 , 1-ring, C 10–12 , levoglucosan, C 13–15 , and C 16–18 ). The cumulated masses and the instantaneous concentrations of gaseous products were obtained under the experimental conditions. The yields of non-hydrocarbon gases and of hydrocarbon gases were about 10.46 and 0.49% at 623 K, 33.68 and 0.89% at 700 K, 64.52 and 1.05% at 788 K, and 79.10 and 1.63% at 938 K, respectively. The estimation of the mass of tar, yielded at various pyrolysis temperatures was also made. The results of this study might be useful for the design of pyrolysis process as well as for determining the pyrolysis mechanisms of the uncoated printing and writing paper.

Glycolysis of rigid polyurethane (PU) has been investigated to provide useful data for the recycling of waste refrigerators. The glycolysis experiments were performed under atmospheric pressure in a stirred flask kept at a constant temperature. Diethylene glycol (DEG) and potassium acetate (KAc) were used as the solvent and catalyst in the glycolysis system, respectively. The properties of the glycolysis products were determined by analyzing the hydroxyl value, mass mean molecular weight (Mw), viscosity, and the conversion of the –NCOO– functional group in PU. The results indicate that an adequate concentration of KAc is about 2% of the weight of the PU and an adequate reaction time is about 2 h. The yields of glycolysis products are about 87–95% for our experimental conditions. Thus, the recovery of liquid products containing polyols can be achieved by the distillation of glycolysis products. # 2002 Elsevier Science Ltd. All rights reserved.

Poly(vinyl alcohol) (PVA) can be used to manufacture the immobilizing support of microorganisms in wastewater treatment systems. The withdrawn activated sludge contains lots of PVA. Before consider...

Previous efforts were made to convert the oil sludge into useful resources such as lower molecule organic compounds and carbonaceous residues by pyrolysis with the carrier gas of N2. The liquid products (condensates of gases at 298 K) obtained from the pyrolysis of oil sludge are close to diesel oil. However, they contain a significant amount of vacuum residues of about 9.57 wt %, which decrease the qualities of liquid products. In the present study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in the northern Taiwan is used as the raw material for the pyrolysis. The influences of using inexpensive and nonharmful additives on the possible improvement of the pyrolysis of oil sludge are investigated. The additives employed include two groups: (1) aluminum compounds (Al, Al2O3, and AlCl3), and (2) iron compounds (Fe, Fe2O3, FeSO4·7H2O, FeCl3, and Fe2(SO4)3·nH2O). For the increases of conversion X, the additives provide the offers on the order of Fe2(SO4)3·nH2O > Fe2...

Oxidative thermal treatment of oil sludge with different oxygen concentrations of air by using a dynamic thermogravimetric (TG) reaction system is investigated. The experimental conditions employed are: gas flow rate of 50 cm3/min (value at 298 K) for 300 mg dry waste, a constant heating rate of 5.2 K/min, the oxygen concentrations in air of 1.09, 8.62 and 20.95 vol. % O2, and the temperature (T) range of 378-873 K. From the experimental results, the residual mass fractions (M) are about 78.95, 28.49, 8.77 and 4.13 wt. % at the oxidative T of 563, 713, 763 and 873 K for the case with 20.95 vol. % O2, respectively. The values of M with 8.62 and 1.09 vol. % O2 at T of 873 K are 4.87 and 9.44 wt. %, respectively. The distillation characteristics of the oil portion of liquid products (condensates of gas at 298 K) from the oxidative thermal treatment of oil sludge with 20.95 vol. % O2 at T of 378-873 K is close to those of commercial gasoline. Nevertheless, the liquid product contains a large amount of water. The distillation characteristics of the oil portions of liquid products with 8.62 and 1.09 vol. % O2 at T of 378-873 K are close to those of diesel and fuel oils, respectively. The oil quality with 8.62 vol. % O2 is better than that with 1.09 vol. % O2. However, the liquid product with 8.62 vol. % O2 still contains a large amount of water; nonetheless, that with 1.09 vol. % O2 is with negligible water. Compared with the oil product of nitrogen pyrolysis, the oil quality with 1.09 vol. % O2 is better. Certainly, low oxygen conditions (i.e. 1.09 vol. % O2) not only accelerate the thermal reaction of oil sludge, but also at the same time avoid or reduce the production of water. Further, from the analysis of benzene (B), ethylbenzene (E), toluene (T) and iso-xylene (X) concentrations of the oil portion of liquid products, the BETX concentrations of oil with 20.95 vol. % O2 are higher than those with 8.62 and 1.09 vol. % O2. The yields of liquid products with 20.95, 8.62 and 1.09 vol. % O2 at T of 378-873 K are 31.96, 34.42 and 37.3 wt. %, respectively. From the experimental results, the improvement effects of oxygen on the qualities of the oil portion of liquid products are obvious. The above technique not only formats good quality gasoline and diesel oils but also reduces large amount of oil sludge. If the oil exists with water, it may be obtained by further separation or collected by fractional condensation.

The tetra pack is one of the principal materials in municipal solid wastes (MSW). The amount of waste tetra pack is over 6000 tons per year in Taiwan. The components of tetra pack are kraft paper (about 70 wt %), low-density polyethylene (LDPE, about 25 wt %), and aluminum foil (about wt 5%), generally. Accordingly, its conversion to useful fuels as well as the recycling aluminum foil has become a worthy goal from not an economic, but also from an environmental standpoint. In this study, the experiments for the partial oxidation of tetra pack were carried out with a thermogravimetric analysis (TGA) reaction system. The pyrolysis reactions of tetra pack were performed in four different oxygen concentrations (CO2) of 5.4, 10.4, 14.8, and 21.0% for analyzing the pyrolysis products. The gaseous products were collected at room temperature (298 K) and analyzed by gas chromatography (GC). The residues were collected at the pyrolysis temperatures 575, 656, 700, 730, and 1073 K and analyzed by elemental analyzer, ...

The pyrolysis of tetra pack in nitrogen was investigated with a thermogravimetric analysis (TGA) reaction system. The pyrolysis kinetics experiments for the tetra pack and its main components (kraft paper and low-density poly(ethene) (LDPE)) were carried out at heating rates (β) of 5.2, 12.8, 21.8 K min−1. The results indicated that the one-reaction model and two-reaction model could be used to describe the pyrolysis of LDPE and kraft paper respectively. The total reaction rate of tetra pack can be expressed by the summation of the individual class of LDPE and kraft paper by multiplying the weighting factors. The pyrolysis products experiments were carried out at a constant heating rate of 5.2 K min−1. The gaseous products were collected at room temperature (298 K) and analyzed by gas chromatography (GC). The residues were collected at some significant pyrolysis reaction temperatures and analyzed by an elemental analyzer (EA) and X-ray powdered diffraction (XRPD). The accumulated masses and the instantaneous concentrations of gaseous products were obtained under the experimental conditions. The major gaseous products included non-hydrocarbons (CO2, CO, and H2O) and hydrocarbons (C1–5). In the XRPD analysis, the results indicated that pure aluminum foil could be obtained from the final residues. The proposed model may be supported by the pyrolysis mechanisms with product distribution. © 2001 Society of Chemical Industry

The pyrolysis of high-density polyethylene (HDPE), the principal component of plastics in municipal solid waste, was studied in the thermal gravimetric analysis reaction system containing hydrogen chloride (HCl) gas. The pyrolysis experiments were carried out over a range of room temperatures to 850 K. The results indicated that HCl retarded the pyrolytic reaction of HDPE at high HCl concentration CHCl range. The gas/liquid products and solid residues were collected and analyzed by gas chromatography, mass spectrometer, and elemental analyzer. The distributions of gas/liquid products and solid residues as well as the effects of HCl on the pyrolytic products were investigated. The results of this study are useful for the utilization of HDPE as an energy resource and determining the thermal degradation behavior of HDPE in an incinerator.

Oil sludge, if unused, is one of the major industrial wastes that needs to be treated for the refinery or petrochemical industry. It contains a large portion of combustible components with high heating values. Obviously, the conversion of oil sludge to various useful materials such as lower molecular weight organic compounds and carbonaceous residue via pyrolysis not only solves the disposal problem but also matches the appeal of resource utilization. In this study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in northern Taiwan is used as the raw material of pyrolysis. Its heating value of dry basis and low heating value of wet basis are about 10681 and 5870 kcal/kg, respectively. The pyrolysis of oil sludge is conducted by using nitrogen as carrier gas in the temperature range 378−873 K. The pyrolytic reaction is complex and significant in the range 450−800 K. The residues of pyrolysis of oil sludge exhibit very high viscous form below 623 K (pyrolysis temperatu...

Oil sludge, if unused, is one of the major industrial wastes requiring treatment from petroleum refinery plants or the petrochemical industry. It contains a large amount of combustibles with high heating values. The treatment of waste oil sludge by burning has certain benefits; however, it cannot provide the useful resource efficiently. On the other hand, the conversion of oil sludge to lower molecular weight organic compounds by pyrolysis not only solves the disposal problem but also has the appeal of resource utilization. The major sources of oil sludge include the oil storage tank sludge, the biological sludge, the dissolve air flotation (DAF) scum, the American Petroleum Institute (API) separator sludge and the chemical sludge. In this study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in northern Taiwan is used as the raw material of pyrolysis. Its heating value of dry basis and low heating value of wet basis are about 10681 kcal kg−1 and 5870 kcal kg−1, respectively. The removal of the moisture from oil sludge significantly increases its heating value. The pyrolysis of oil sludge is conducted by the use of nitrogen as the carrier gas in the temperature range of 380–1073 K and at various constant heating rates of 5.2, 12.8 and 21.8 K min−1. The pyrolytic reaction is significant at 450–800 K and complex. For the sake of simplicity and engineering use, a one-reaction kinetic model is proposed for the pyrolysis of oil sludge, and is found to satisfactorily fit the experimental data. The activation energy, reaction order and frequency factor of the corresponding pyrolysis reaction in nitrogen for oil sludge are 78.22 kJ mol−1, 2.92 and 9.48 × 105 min−1, respectively. For precise use, the two- and three-reaction models are proposed to describe the pyrolysis results. Among the three models proposed, the three-reaction model gives the best fit. These results are very useful for the proper design of the pyrolysis system of the oil sludge under investigation. © 2000 Society of Chemical Industry

The thermal degradation kinetics of polypropylene (PP) in steam was investigated with a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out in the 500–800 K temperature range at various constant heating rates of 1, 2, and 5 K/min. The partial pressure of steam in the system was adjusted to 0.24 atm, which is seen in most municipal solid waste (MSW) incinerators in Taiwan. The results indicated that the water molecule significantly enhanced the thermal degradation rate of PP. The corresponding activation energy, preexponential factor, and reaction order were determined. It was found that thermal degradation of PP in steam can be adequately described by an overall rate equation.

The pyrolytic reaction of chlorinated plastics such as poly(vinyl chloride) (PVC) releases hydrogen chloride (HCl). The HCl released from the pyrolysis, in turn, may affect the mechanisms of the pyrolytic reactions. In this study, the pyrolysis of high-density polyethylene (HDPE), being the principal component of plastics in the municipal solid waste (MSW), was carried out in the thermal gravimetric analysis (TGA) reaction system containing HCl gas. The results indicated that HCl inhibited the pyrolytic reaction of HDPE. The activation energies, pre-exponential factors, and reaction orders of the reactions corresponding to the various concentrations of HCl ( C HCl ) were obtained in the range of the experimental conditions. The results of this study are useful for the utilization of HDPE as an energy resource and for determining the thermal degradation rate of HDPE in an incinerator.

The pyrolysis kinetics of a rubber mixture was investigated by a dynamic thermogravimetry reaction system at heating rates of 3, 5 and 7 K/min, in a nitrogen atmosphere, over the temperature range of 400 to 950 K. The results indicated that the pyrolytic reaction rates of rubber mixture can be represented by the summation of the corresponding reaction rates of the rubber components, based on their mass fractions. Satisfactory agreements between the proposed reaction model and the experimental results could be obtained. The results of this study are useful for the utilization of scrap rubber mixtures as an energy resource.

The pyrolysis kinetics of cellulosic coated printing and writing paper, a principal component of municipal solid waste (MSW) in Taiwan, were investigated by thermogravimetric analysis in nitrogen over the temperature range 450–900 K at heating rates of 1, 2 and 5 K min−1. The t.g.a. curves indicated two principal reactions, distinguished by significant and distinct mass changes over the experimental range. The pyrolysis of coated paper could be adequately described by a two-reaction model. The corresponding activation energies, pre-exponential factors and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed model.

The pyrolysis kinetics of a mixture of the four principal papers (uncoated and coated printing/writing papers, newsprint, and tissue paper) in municipal solid waste (MSW) was investigated with a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out in a nitrogen environment over the temperature range of 450 to 900 K at various constant heating rates of 1, 2, and 5 K min−1. The results indicated that there were two principal reactions in the TGA curves as distinguished by the two significant and distinct mass changes over the experimental conditions. The pyrolysis of a paper mixture can be adequately described by a two reaction model. The effect of interaction between the components of a paper mixture on the pyrolysis rate was insignificant. The results for the pyrolysis rates of paper mixtures with slow heating rates can be represented by the weighting sum of the corresponding pyrolysis rates of the components of papers in MSW. The experimental results were satisfactorily fitted by the proposed chemical reaction kinetic equations and able to provide useful data for the design of a pyrolytic processing system for the waste papers in MSW. © 1997 SCI.

The thermal degradation kinetics of polybutadiene rubber (BR) was investigated by dynamic thermogravimetry, in a nitrogen atmosphere, over the temperature range 177–577 °C and at constant nominal heating rates of 3, 5 and 7 °C/min, respectively. Two distinct mass change stages in the thermogravimetric analysis (TGA) curves indicated that the degradation of BR may be attributed to two reactions. The corresponding activation energies, frequency factors and reaction orders of the two reactions were determined. A simplified two-reaction model based on the TGA curves was also proposed for engineering purposes. Satisfactory agreements between the proposed model and the experimental results were obtained. The results of this study are useful for the utilization of scrap BR as an alternative energy resource.

The pyrolysis kinetics of commercial-grade styrene–butadiene rubber (SBR), which is one of the major constituents of tyre rubber as well as one of the principal products of the rubber industry in Taiwan, was investigated by a dynamic thermogravimetry (TG) reaction system in a nitrogen atmosphere over the temperature range of 400 to 950 K at the nominal heating rates of 3, 5 and 7 K min−1. The experimental results indicated that the pyrolysis of SBR may be attributed to three reactions, with three distinct mass change characteristics in the mass-loss curves of reactant deduced from the experiments. The corresponding activation energies, frequency factors and reaction orders of the three reactions were determined. A simplified three-reaction model based on the mass-loss curves of reactant was also proposed for engineering purposes. Satisfactory agreements between the proposed model and the experimental results were obtained. The results of this study are useful for the utilization of scrap SBR as an energy resource.

The pyrolysis kinetics of cellulosic uncoated printing and writing paper, which is one of the principal materials contributing to the municipal solid waste (MSW) of Taiwan, was investigated with a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out in a nitrogen environment in the 450–850 K temperature range at various constant heating rates of 1, 2, and 5 K/min. The results indicated that there were two principal reactions in TGA curves as distinguished by the two significant and distinct mass changes over the experimental conditions. The pyrolysis of uncoated printing and writing paper can be adequately described by a two-reaction model. The corresponding activation energies, preexponential factors, and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed chemical reaction model.

The pyrolysis behavior of poly(vinyl chloride) (PVC) at high conversion ( X > 0.6) was examined with a thermal gravimetric analysis reaction system at heating rates of 1, 2 and 5 K min −1 . The experiments were carried out over the temperature range 400−800 K and in a nitrogen atmosphere. The results indicated that the reaction pattern of PVC pyrolysis at high conversion can be described by the competitive reaction model with the production of volatiles and char. The corresponding activation energy, pre-exponential factor and reaction order were determined. These results may assist in dealing with the pyrolysis of plastic mixtures containing waste PVC from a knowledge of the behavior of the pure PVC component.

The pyrolysis of polyvinyl chloride (PVC) was examined with a thermal gravimetric analyzer (TGA). The experiments were carried out over the temperature range of 400-800 K at three heating rates of 1, 2, and 5.5 K/min and in a nitrogen atmosphere. The results indicate that the entire process of PVC pyrolysis under the experimental conditions of this investigation consists of two distinct pyrolysis stages, namely, the thermal dehydrochlorination and the breakdown of the intermediate products produced after the dehydrochlorination stage. The corresponding activation energy, pre-exponential factor, and reaction order were determined. A two-stage pyrolysis model, which is composed of four reactions including a number of independent, consecutive and competitive reactions with volatiles and solid products, was developed. This kinetic model gives good agreement with the experimental results. On a etudie la pyrolyse du chlorure de polyvinyle (PVC) a I'aide d'un analyseur thermogravimetrique (TGA). Les experiences ont ete menees pour une vaste gamme de temperatures de 400 a 800 K a trois taux de chauffage, soit 1, 2 et 5,5 K/min, en milieu azote. Les resultats indiquent que le processus de pyrolyse du PVC dans ies conditions experimentales de cette etude comprend deux etapes distinctes de pyrolyse, a savoir la deshydrochloruration thermique et la fracturation des produits intermediaires produits apres l'etape de deshydrochloruration. On a detennine l'energie d'activation, le facteur pre-exponentiel et l'ordre de reaction correspondants. Un modele de pyrolyse en deux etapes comportant quatre reactions dont plusieurs reactions independantes, consecutives et competitives avec des produits volatils et solides, a ete mis au point. Les predictions de ce modele cinetique concordent bien avec les resultats experimentaux.

The pyrolysis kinetics of cellulosic toilet tissue paper, which is one of the principal materials contributing to municipal solid waste (MSW) in Taiwan, was investigated by a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out over the temperature range of 450–850 K at various heating rates, and in a nitrogen atmosphere. The results indicated that there were two principal reactions in TGA curves as distinguished by the two significant and distinct weight changes over the experimental conditions. The pyrolysis behavior of tissue paper can be adequately described by a two reaction model. The corresponding activation energies, pre‐exponential factors, and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed chemical reaction model.

Different from most previous studies with quantity-limited data, this paper presents PCDD/F content characterization in the fly ash discharged from sixteen large-scale commercial MSWIs. From the results with over hundreds of data using periodically sampling and analysis, it was found that the PCDD/F contents in the fly ash were from 9.07 to 46.68 ng/g, d.w., and if based on international toxicity equivalent quantity, they were from 0.78 to 2.86 ng I-TEQ/g, d.w. The higher chlorinated PCDDs likely dominated more than lower chlorinated PCDDs, but this tendency was not for PCDFs. The OCDD had the highest contribution to the total PCDD/F content, but if based on I-TEQ content, 2,3,4,7,8-PeCDF is the PCDD/F congener with the highest toxicity contribution. Moreover, the PCDD/F characteristic index (DCI) is suggested using the representative congener content of 2,3,4,7,8-PeCDF to characterize the fly ash. The DCI is 0.875 ± 7.6% for the fly ash discharged from the MSWI with the APCD assembly of SD, AC and BF. The findings obtained in this work provide overview information on the PCDD/F content characterization in fly ash. They will provide PCDD/F fingerprint information to distinguish from other PCDD/F sources, like steel refinery industry, hazardous waste incinerators, or cement kilns, and thus be applied to fly ash management in the environment.

The pyrolysis kinetics of six principal plastic materials of municipal solid waste (MSW) and their mixtures were investigated by a thermal gravimetric analysis (TGA) reaction system at various heating rates of 1, 2, and 5.5 K/min and in nitrogen atmosphere. The results indicated that the pyrolysis of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and acrylonitrile-butadiene-styrene (ABS) copolymer can be considered as one stage reaction and described by an overall rate equation. The pyrolysis history of polyvinyl chloride (PVC) in the experimental conditions of this investigation consisted of two distinct stages with four reactions, which can be also expressed by an overall rate equation. The interaction between the components of plastic mixture in the pyrolysis was insignificant. The results for the slow heating rate pyrolysis of plastic mixtures can be represented by the combining of the corresponding rates of the components of plastic of MSW together with a prediction for the char yield. The experimental results were satisfactorily fitted by the proposed chemical reaction kinetics equations.

In this study, measurements of elutriation rate were carried out in a bench scale bubbling fluidized bed incinerator, which was used to combust sludge cake. The particle size distribution and ignition loss were analyzed to study the elutriation characteristics of bubbling fluidized bed incineration. Drawn from the experimental data, the elutriation rate constant K(i)* for fine particles were obtained and correlated with parameters. It was found that most of the solid particles (about 95%) elutriated came from the fluidized medium (inorganic matters), but few came from unburned carbon particles or soot (about 5%). Finally, this paper lists a comparison of K(i)* between this study and the published prediction equations derived or studied in non-incineration modes of fluidized bed. A new and modified correlation is proposed here to estimate the elutriation rate of fine particles emitted from a bubbling fluidized bed incinerator. Primary operation variables (superficial gas velocity and incineration temperature) affecting the elutriation rate are also discussed in the paper.