Pyrolysis Tests Research Articles

Fuel oil from ABS using a tandem PEG-enhanced denitrogenation–pyrolysis method: Thermal degradation of denitrogenated ABS

Thermal degradation of ABS and denitrogenated ABS samples (DABS), prepared by sequential hydrolysis of ABS using PEG/NaOH, has been investigated under inert gas and at atmospheric pressure in a temperature range between 40 and 700 °C, by means of TGA, TGA-IR, and TGA-MS, to study the link between original structure of DABS and eventual pyrolysis. For DABS, thermal decomposition begins at the side groups of –CONH 2 and/or –COOH, resulting in a lower initial degradation temperature of DABS (around 330 °C) relative to ABS (372.5 °C). Moreover, less HCN and acrylonitrile evolve from the DABS samples, while the evolution of CO 2 starts earlier and becomes more important, in line with the decreased number of –CN groups and the increased number of –COOH functional groups due to hydrolysis. The results from thermo-analytical experiments were confirmed by batch pyrolysis tests: the nitrogen content of oil produced from DABS pyrolysis is much lower, compared with that from ABS, proving that effective denitrogenation of ABS prior to pyrolysis is beneficial to the quality of pyrolysis oil.

Polymeric Cracking of Waste Polyethylene Terephthalate to Chemicals and Energy

ABSTRACT Polyethylene terephthalate (PET) is a widely used thermo-plastic. PET residues represent on average 7.6 wt% of the different polymer wastes in Europe. Pyrolysis of these wastes is attracting increasing interest, and PET is a potential candidate for this thermal process. The paper measures and discusses the kinetics of the pyrolysis reaction in terms of the reaction rate constants as determined by dynamic thermogravimetric analysis, with special emphasis on the required heating rate to obtain relevant results. The product yields and compositions are also determined. Gaseous products represent 16–18 wt%. The amounts of condensables and carbonaceous residue are a function of the operating mode, with slow pyrolysis producing up to 24 wt% of carbonaceous residue. Major condensable components are benzoic acid, monovinyl terephthalate, divinyl terephthalate, vinyl benzoate, and benzene. The present paper complements previous literature findings by (1) the study of the influence of the heating rate on the reaction kinetics in dynamic pyrolysis tests, (2) the iso-thermal investigation in a fluidized bed reactor to pyrolyze PET, and (3) the assessment of upgrading and recovery of the products. The paper concludes with a proposed reactor recommendation for PET pyrolysis, in either the bubbling or circulating fluidized bed operating mode. IMPLICATIONS Plastic solid waste (PSW) represents up to 8% by wt and 20% by volume of household waste. Landfill disposal wastes valuable energy and chemical feedstock. Incineration for energetic valorization (waste-to-energy) is applied for ∼50% of PSW. To date, research focuses increasingly on pyrolysis, which has the advantage over incineration of producing value-added chemicals, even from commingled or mixed feedstock. The process gains in efficiency and yield if PSW fractions are collected separately or presegregated. The cost of separate collection is easily overcome by the value of the pyrolysis products. The pyrolysis of polyethylene terephthalate is developed as an example of the above.

Calcium and aluminium-based fillers as flame-retardant additives in silicone matrices II. Analyses on composite residues from an industrial-based pyrolysis test

The second part of this series, devoted to the study of model fire-resistant silicone composites filled with calcium or aluminium-based material which would meet cable industry specifications, focuses on residues obtained after extreme pyrolysis adapted from the NFC 32070 CR1 French standard. Several methods of analysis (among them ESEM, EDX, XRD, Hg pycnometer, and compression tests) have been carried out in order to investigate the microstructure, volume variation, and compression behaviour of silicone composite residues. Calcium-based fillers produced more cohesive residues than aluminium-based fillers. Indeed, the co-crystallisation taking place during pyrolysis, as shown in the first part of this series (Hamdani, S. et al., Polym Degrad Stab, 2010, 95, 1911–1919), produced a dense and strong residue. The strong internal porosity and absence of new crystal formation in residues of aluminium-based filled composites resulted in their low compressive resistance. In addition, water release during the degradation of the latter fillers, favoured residue expansion, high interior porosity and thus weak compression resistance.

Effect of CO2 during Coal Pyrolysis and Char Burnout in Oxy-Coal Combustion

One of the primary concerns in oxy-coal combustion is whether or not conventional coal pyrolysis and char burnout model can be used because of the presence of high CO2 in gas medium around coal particles. This paper attempts to understand the effect of high concentration of CO2 during coal pyrolysis and oxidation by conducting experiments in a drop-tube reactor and a thermogravimetric analyzer (TGA). Two ranks of bituminous coal particles were pyrolyzed in CO2 and Ar atmosphere during the pyrolysis tests and in 21% O2/79% CO2 and air during combustion tests. The results showed that the differences observed during pyrolysis and combustion tests conducted with and without CO2 can be attributed to the effects of char–CO2 reaction. This result implies that char–CO2 reaction should be included in model reactions while modeling coal pyrolysis or char oxidation in oxy-coal combustion. Furthermore, a faster increase in the rate of char burnout during combustion in O2/CO2 relative to that with air for an lvb coal was due to lower activation energy of C–O2 and higher activation value of C–CO2 reaction compared to that of an hvCb coal. This result implies that some coals may be more suitable for oxy-coal combustion which can be identified based on the intrinsic activation energy value of char–CO2 and char–O2 reactions.

Thermal degradation studies and kinetic modeling of cardoon (C ynara cardunculus) pyrolysis using thermogravimetric analysis (TGA)

A key element in the design of sustainable pyrolysis processes is the thermal degradation kinetics of biomass. In this work, pyrolysis tests for cardoon ( Cynara carduculus) stems and leaves were performed in a non-isothermal thermogravimetric analyzer (TGA) in order to determine the thermal degradation behavior of both stems and leaves. The kinetic parameters of the process were evaluated using three different kinetic models, the independent parallel reaction model, KAS and OFW iso-conversional model. Good agreement with the experimental TGA data was observed for all models, the best being with the independent parallel reaction model. A variance in the activation energy with conversion was observed when the KAS and OFW models were employed, which reveals that the pyrolysis of cardoon progresses through more complex and multi-step kinetics.

Air and oxy-fuel combustion characteristics of biomass/lignite blends in TGA-FTIR

Pyrolysis and combustion behavior of indigenous lignite, olive residue and their 50/50wt.% blend in air and oxy-fuel conditions were investigated by using thermogravimetric analyser (TGA) combined with Fourier-transform infrared (FTIR) spectrometer. Pyrolysis tests were carried out in nitrogen and carbon dioxide environments which are the main diluting gasses of air and oxy-fuel environment, respectively. Pyrolysis results of the parent fuels and the blend show that weight loss profiles are almost the same up to a temperature of 700°C in these two environments, indicating that CO2 behaves as an inert gas in this temperature range. However, further weight loss takes place in CO2 atmosphere at higher temperatures due to CO2–char gasification reaction which leads to significant increase in CO and COS formation as observed in FTIR evolution profiles. Comparison between experimental and theoretical pyrolysis profiles of the blend samples reveals that there is no synergy in both atmospheres. Combustion experiments were carried out in four different atmospheres; air, oxygen-enriched air environment (30% O2–70% N2), oxy-fuel environment (21% O2–79% CO2) and oxygen-enriched oxy-fuel environment (30% O2–70% CO2). Replacing N2 in the combustion environment by CO2 causes slight delay (lower maximum rate of weight loss and higher burnout temperature) in the combustion of all samples. However, this effect is found to be more significant for olive residue than lignite. Elevated oxygen levels shift combustion profiles to lower temperatures and increase the rate of weight loss. Combustion profiles of olive residue/lignite blends lie between those of individual fuels. Comparison between experimental and theoretical combustion profiles and characteristic temperatures of the blend samples indicates synergistic interactions between the parent fuels during co-combustion of olive residue and lignite.

From trimethylvinylsilane to ZrC–SiC hybrid materials

We describe a new route to synthesize hybrid ZrC–SiC materials in a one-pot procedure. Polycarbosilane was generated from trimethylvinylsilane in the presence of ZrC powder. A specific interaction between the polymer and the ceramic particles was evidenced. The conversion of precursor into composite was achieved by pyrolysis under argon up to 1100 °C. From thermogravimetric analyses, pyrolysis tests and SEM observations, it has been shown that these hybrid materials kept a stability above 850 °C, and their total mass loss remained lower than 20%.

CARACTERIZAÇÃO E RECICLAGEM QUÍMICA VIA PIRÓLISE DE RESÍDUOS DA FABRICAÇÃO DE PÁS EÓLICAS

A energia eólica é uma forma de energia que seu uso encontra-se em expansão, e junto a esse crescimento, tem-se também o aumento da quantidade de resíduos gerados na fabricação das pás eólicas. Uma forma correta de destinação e aproveitamento desses resíduos é a reciclagem. Porém, esses são constituídos de materiais compósitos, geralmente a resina epóxi e a fibra de vidro; e por possuírem um polímero termofixo (a resina epóxi) na sua composição, a reciclagem convencional via fusão não é possível. Desta forma, a reciclagem química via pirólise apresenta-se como uma alternativa para o aproveitamento desses resíduos, em especial da fibra de vidro que o contém. Após caracterização do resíduo de uma indústria de pás eólicas, verificou-se que se tratava de um material com mais de 70% de fibra de vidro e muito densas. Foram realizados ensaios de pirólise a seco e com óleo de babaçu, considerado o mais interessante perante vários possíveis e no qual o resíduo fica totalmente imerso, facilitando o inchamento e a troca de calor. Em um sistema de aquecimento com vácuo, foram obtidas mais de 97% de fibras em 30 minutos a 310 oC, justamente a temperatura em que uma análise termogravimétrica apontou ser a de início de altas taxas de degradação térmica.

Thermodynamic modelling of co-firing coal and biomass pyrolysis gas in a power plant

The Austrian utility company EVN AG is investigating possibilities to substitute part of the hard coal used in their Dürnrohr power station by biomass pyrolysis gas produced in an upstream rotary kiln at relatively low temperatures of ≤ 600 °C. A major advantage of the low temperature is the retention of alkalis and halogenes in the coke. The aim of the present work was to set up a working thermo-chemical computer model in order to calculate the possible effects that this co-firing may have on corrosion phenomena in the boiler. The work was carried out using the software packages FactSage ® and SimuSage ®. A model was successfully developed and validated using data from laboratory analyses as well as from the power station and a biomass pyrolysis test facility set up next to the plant. The results of the calculations show that the gas produced in the rotary kiln at the planned scale very likely does not pose any potential threat to the power plant.

Combustion behaviour of Turkish lignite in O2/N2 and O2/CO2 mixtures by using TGA–FTIR

The pyrolysis and combustion behaviour of a low calorific value Turkish lignite with high sulphur and ash content in air and oxy-fuel conditions were investigated by using non-isothermal thermo-gravimetric method (TGA) coupled with Fourier-transform infrared (FTIR) spectrometer. Pyrolysis tests were carried out in nitrogen and carbon dioxide environments which are the main diluting gases of air and oxy-fuel environment, respectively. Pyrolysis results show that weight loss profiles are almost the same up to a temperature of 720°C in these two environments, indicating that CO2 behaves as an inert gas in this temperature range. However, further weight loss takes place in CO2 atmosphere at higher temperatures due to CO2–char gasification reaction. Combustion experiments were carried out in four different atmospheres: air, oxygen-enriched air environment (30% O2–70% N2), oxy-fuel environment (21% O2–79% CO2) and oxygen-enriched oxy-fuel environment (30% O2–70% CO2). Combustion experiments reveal that replacing nitrogen in the gas mixture by the same concentration of CO2 does not affect the combustion process significantly but only leads to slight delay in combustion. Overall comparison of derivative thermogravimetry (DTG) profiles shows that oxygen content in the combustion environment is the most effective parameter irrespective of the diluting gas. As O2 concentration increases profiles shift through lower temperature zone, peak and burnout temperatures decrease, weight loss rate increases and complete combustion is achieved at lower temperatures and shorter times. During pyrolysis and combustion tests gaseous products CO2, CO, H2O, CH4, SO2 and COS in flue gas were identified and analyzed by using FTIR. Results indicate that higher CO and COS formation takes place during pyrolysis due to gasification reaction. Gaseous species evolution trends in combustion tests are found to be almost identical in oxygen enriched conditions independent of the diluting gas.

Analysis and modelling of wood pyrolysis

In many industrial processes wood is treated as big fragments or pellets. In such conditions kinetics and yields are different with respect to the case of particles with few mg weight. However most of published kinetic models were based on experimental data obtained with very small samples. In this work pyrolysis of wood pellets was investigated by using a special experimental device which allowed to determine kinetics of total weight loss, gas and tar production. Two different heating rates, 0.05 and 1 K/s, were employed to determine kinetic parameters. Dynamic and isothermal pyrolysis tests were carried out on beech and pine wood previously dried in an oven. A simple but realistic kinetic scheme was proposed able to take into account the phenomena that happen in big wood particles. The numerical parameters were determined from the results of experimentation on beech wood. The proposed kinetic model takes into account the presence of two different stages during pyrolysis: a first one involving only unreacted wood and a second one where the products not yet escaped from the solid matrix react further. This kinetic model allowed to fit the experimental data quite well. The model was successfully validated with tests performed at an elevated heating rate (approximately 60–100 K/s) of the external surface of the pellets. In these conditions, the pellets showed a marked gradient of temperature inside, which was suitably considered.

Evaluation of optimization schemes and determination of solid fuel properties for CFD fire models using bench-scale pyrolysis tests

CFD fire modeling tools are continuously developed and improved to increase their predictive capability of phenomena observed in practical applications. Such models require that “effective” material properties be provided so that the pyrolysis codes used in the models can properly estimate the thermal degradation of solid fuels involved in a fire situation. This paper presents analyses aimed at evaluating the plausibility of obtaining material properties numerically from pyrolysis data collected in a Fire Propagation Apparatus (FPA). A theoretical pyrolysis model is used to simulate the experimental data and the input parameters (i.e. the material properties) are adjusted to provide the best possible agreement between simulations and experiments. This is done via the application of evolutionary optimization methodologies. First, available optimization techniques are evaluated using synthetic data and it is shown that the Shuffled Complex Evolution approach ( [17]) can recover the input parameters with high accuracy, efficiency, and robustness. Second, the algorithm is applied to experimental FPA pyrolysis data of practical materials: polymethyl methacrylate (PMMA), single-wall corrugated board, and chlorinated polyvinyl chloride (CPVC).

Evaluation of production yield and thermal processing of switchgrass as a bio-energy crop for the Mediterranean region

Switchgrass, a warm-season perennial grass, could play an important role for Europe in supplying sustainably produced lignocellulosic biomass, as its establishment cost is low and its productivity high under low input conditions. The aim of this study was to evaluate the adaptability and biomass productivity of switchgrass under the Greek climatic conditions and furthermore its suitability for heat and electricity applications, by performing fuel analyses, pyrolysis and combustion tests. Three-year field trials with different irrigation and fertilization levels showed that each level of irrigation had a significant effect on dry matter yields, while nitrogen effect was not pronounced. Yields were similar in the second and third year and ranged from 15.4% to 24 tons/ha. Fuel characterization showed a high volatile content and calorific value, whereas low ash, sulphur, nitrogen and chlorine contents. Ashes were rich in Si, K and P and some micronutrients, such as Zn. The ash fusion temperatures of the stems, which were richer in alkali, were low for combustion processes, revealing slagging/fouling problems in boilers without crop pre-treatment. However, their ash content was very low. The thermochemical reactivity of the stems was higher than that of the leaves, especially in air. The greater amount of minerals in the leaves inhibited the reaction rates in either nitrogen or air atmospheres. A first-order parallel reactions model for pyrolysis and a power low model for combustion fitted the experimental results accurately and kinetic parameters were derived. Irrigation/fertilization treatment had a positive effect on the combustion performance of the stems.

Combustion properties of some power station biomass fuels

In this study, the combustion properties of three of the UK’s commonly imported biomass fuels for co-firing, which are palm kernel expellers, shea residue, and waste from olive oil production are examined. The fuels were characterised and their thermal decomposition properties were studied by thermogravimetric analysis (TGA). Additionally the products from their devolatilisation were identified by gas chromatography–mass spectrometry (py–GC–MS) analysis of the evolved vapours and tars from high heating rate pyrolysis tests. Finally, chars from the fuels were prepared, analysed, and combustion studies were conducted by TGA–MS to determine the conversion of char-nitrogen to different nitrogen-containing species. In general, the main constituents of their ash fractions were K, Si, Ca and Mg, resulting in high alkali indices, which predict a large tendency to fouling. The pyrolysis and combustion kinetic parameters, estimated from TGA studies of these fuels and their chars, are much lower than those reported in the literature for lignocellulosic biomass. It is suspected that there is oil/fat evaporation processes overlapping with the decomposition of their lignocellulosic fractions, which significantly affects the apparent kinetics. The pyrolysis conditions used promoted depletion of nitrogen in the char, resulting in approximately 79–91% of the fuel-N being released with the volatiles. In combustion of the char, NO x and N 2 are the major nitrogen compounds detected. Another primary product, HCN, was detected from the combustion of some of the fuel chars, as well as C 2N 2.

Pyrolysis and combustion of oil palm stone and palm kernel cake in fixed-bed reactors

The main objective of this research was to investigate the main characteristics of the thermo-chemical conversion of oil palm stone (OPS) and palm kernel cake (PKC). A series of combustion and pyrolysis tests were carried out in two fixed-bed reactors. The effects of heating rate at the temperature of 700°C on the yields and properties of the pyrolysis products were investigated. The results from the combustion experiments showed that the burning rates increased with an increase in the air flow rate. In addition, the FLIC code was used to simulate the combustion of the oil palm stone to investigate the effect of primary air flow on the combustion process. The FLIC modelling results were in good agreement with the experimental data in terms of predicting the temperature profiles along the bed height and the composition of the flue gases.

CFRP-Recycling Following a Pyrolysis Route: Process Optimization and Potentials

Pyrolysis is a well known method to recover carbon fibers from composite waste. In order to bring these recycled carbon fibers back into new composites, and to provide a `closed loop' for this material, their properties have to be investigated and proved suitable for new products. In a former study a strong influence of the pyrolysis process on the surface of the recovered fibers was found. This in turn influenced other properties like fiber strength, electrical properties and fiber—matrixadhesion. These results offer the possibility to control individual properties of recycled carbon fibers and their composites, but on the other hand they indicate a necessity for process optimization in order to provide a high quality of the recycled fibers. In this study different process parameters during pyrolysis were investigated and optimized in order to provide the reclaimed carbon fibers with properties close to new fibers. The optimization was done by labscale pyrolysis experiments performed in a thermogravimetric analyzer (TGA), with variation of pyrolysis temperature, isothermal dwell time and oven atmosphere, respectively. The recovered fibers were analyzed by scanning electron microscopy and Raman spectroscopy. Finally a pyrolysis test on a semi-industrial-scale was successfully performed to demonstrate the technical viability of the optimized process parameters.

Primary tar of different coking coal ranks

Abstract The aim of the present work is to discuss the differences in the compositions of primary tars collected by means of Gray-King (GK) pyrolysis tests from coking coals of different origin and rank. Ten bituminous coals were pyrolyzed at two different temperatures, 450 and 550 °C, which are known to be important in the conversion processes of coal. Low temperature tars were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS), and High-Performance Liquid Chromatography (HPLC). The results indicate that low temperature tars are mainly formed by aromatic compounds containing different types of substituents (alkyl, aryl, heteroatomic and heterocyclic). When the coal rank increases, the amount of aliphatic and polar compounds decreases due to the influence of coal composition, while the amount of aromatic compounds such as naphthalenes, phenanthrenes, fluorenes, benzofluorenes, and their alkyl derivatives rises as a consequence of the increase in the aromaticity of the parent coal.

Combination of combustion with pyrolysis for studying the stabilization process of sludge in landfill

Study on the stabilization processes is important to follow the landfill process and evaluate quality of organic matters. However, a simple, yet reliable and widely acceptable analytical tool to evaluate the degree of stability remains to be found. Temperature programmed combustion and pyrolysis tests were carried out to investigate the stabilization degree of sludges and demonstrate applicability of thermal methods in waste management. By the combination of combustion and pyrolysis, we can get more information of the sludges and reaction happened in the programmed heating process than combustion only. TG/DTG analysis of sludge combustion helps us to know about the variation of different kinds of organic matters and the degradation degree of the anaerobic stabilization process. The decreasing tendency of DSC peaks reveals the stabilization process is still ongoing.

A kinetic study on the devolatilisation of animal derived byproducts

The thermal degradation characteristics and chemical kinetics of meat and bone meals (MBM) during the volatiles release stage are investigated by thermogravimetry. In addition to the characterization of the animal by-product, a TA Q600 thermogravimetric analyser was used to evaluate the devolatilisation behaviour and determine the kinetic parameters over the temperature range of 30–1000 °C. Non-isothermal pyrolysis tests were conducted at ambient pressure, for four heating rates (5, 20, 50 and 100 °C/min), and particle sizes being between 150–250 μm. The independent parallel, first order, reactions model was used for the simulation of the pyrolysis data, while the effect of mineral matter presence on kinetic constants was evaluated. MBM decomposition presented two distinct weight loss steps and increased conversion rates were attained at higher heating regimes. The model elaborated to describe the thermal devolatilisation of MBM considers four fractions decomposing simultaneously. Accurate predictions of experimental data were achieved in all test cases. Demineralisation resulted in enhanced kinetic constants for the pseudo-reactions at the lower temperature regions.

TG study on pyrolysis of biomass and its three components under syngas

Pyrolysis of sawdust and its three components (cellulose, hemicellulose and lignin) were performed in a thermogravimetric analyzer (TGA92) under syngas and hydrogen. The effect of different heating rates (5, 10, 15 and 20 °C/min) on the pyrolysis of these samples were examined. The pyrolysis tests of the synthesized samples (a mixture of the three components with different ratios) were also done under syngas. The distributed activation energy model (DAEM) was used to study the pyrolysis kinetics. It is found that syngas could replace hydrogen in hydropyrolysis process of biomass. Among the three components, hemicellulose would be the easiest one to be pyrolyzed and then would be cellulose, while lignin would be the most difficult one. Heating rate could not only affect the temperature at which the highest weight loss rate reached, but also affect the maximum value of weight loss rate. Both lignin and hemicellulose used in the experiments could affect the pyrolysis characteristic of cellulose while they could not affect each other obviously in the pyrolysis process. Values of k 0 (frequency factor) change very greatly with different E (activation energy) values. The E values of sawdust range from 161.9 to 202.3 kJ/mol, which is within the range of activation energy values for cellulose, hemicellulose and lignin.