Bench-scale Pyrolysis Research Articles

Hydrochars derived via wet torrefaction of empty fruit bunches: Effect of temperature and time, comparison to oil palm trunks counterpart, and their pyrolysis behavior

In this study, hydrochars derived from the wet torrefaction of empty fruit bunches (EFB) were characterized and compared to those of oil palm trunks (OPT). Then, the kinetics modelling of EFB-derived hydrochars was evaluated and compared with the Distributed Activation Energy Model (DAEM) under logistics distribution via thermogravimetric analysis (TGA) under pyrolytic conditions at different heating rates. Bench-scale pyrolysis of EFB-derived hydrochars were also performed and characterized. This study elucidates the effect of prolonged residence time (3–72 hours) at different temperatures (180–220 °C) on the wet torrefaction of EFB, and comparison to OPT provides an understanding of wet torrefaction mechanisms. The pyrolysis kinetics of EFB-derived hydrochars provide insights into their pyrolysis behavior and their potential in pyrolytic application. Increased temperature and residence time enhanced the higher heating value (HHV) of the hydrochars at the expense of low mass yield. Hydrochars obtained at 220 °C and 72 hours had the highest HHV at 27.4 ± 0.5 MJ kg−1 with a mass yield of 38.3 ± 2 wt%. EFB-derived hydrochars had a higher mass yield than OPT-derived hydrochars. The van Krevelen diagram revealed that dehydration was the primary reaction pathway for EFB and OPT-derived hydrochars. SEM showed the formation of secondary deposits on both EFB and OPT hydrochars. EFB-derived hydrochars obtained at 220 °C and 72 hours had the highest mean activation energy (E0) with a distribution of activation energy (σ) from 176.7 to 181.7 kJ mol−1 and 43.4–49.9 kJ mol−1, respectively. The increased mean and distribution of activation energies were attributed to the lignin-dense structure of the hydrochars. The kinetic parameters of the hydrochars were also independent of heating rates at low heating rates (< 20 °C min−1). The thermal stability of the pyrochars obtained from EFB-derived hydrochars enabled their applications in fields such as carbon support, activated carbon, water purification process, or carbon sequestration.

Deactivation by coking of industrial ZSM-5 catalysts used in LDPE pyrolysis and regeneration by ozonation process – Bench scale studies

Study of the catalytic deactivation during successive uses of ZSM-5 catalysts in bench-scale pyrolysis of low-density polyethylene (200:20 g LDPE:ZSM-5) has been carried out in a semi-batch reactor at 450 °C. The correlation between coke formation over catalyst properties and selectivity during pyrolysis is observed. The loss of catalytic performances translates into a significant drop of aromatics and an increase of waxes in pyrolysis products. The observed deactivation is due to the formation of heavy coke over the catalysts, causing surface hindering, porosity blockage and acid sites diminution. The capacity of ozonation process to regenerate such coked catalysts around 100 °C is demonstrated using a fixed bed reactor. Different times of exposure are investigated to evaluate ozonation efficiency. By using this coke oxidizing treatment during 48 h, regenerated catalysts recovered their initial textural and chemical characteristics (porous volume and acidity) as well as their catalytic performances (similar aromatics proportion as the first pyrolysis).

Kinetic parameter optimization for the bench-scale pyrolysis via chemistry informed neural network

Numerical simulation of bench-scale pyrolysis behaviors is an important step in understanding the pyrolysis progress and modeling fire growth. However, it is usually difficult to measure accurate value of involved kinetic parameters even with state-of-the-art instruments due to the complicated kinetics associated with a large number of tandem reactions. In this paper, a chemistry informed neural network (CINN) framework is reported aiming at optimizing kinetic parameters for bench-scale pyrolysis with a high computational efficiency, where a temperature-dependent Arrhenius equation is formulated as a neuron in the CINN. With a transparent poly (methyl methacrylate) (PMMA) slabs as an example, the gradients of CINN parameters are analytically derived so that it does not need to repeatedly solve governing equations for the evaluation of gradients based on finite difference methods. Results show that the gradient-based training algorithm successfully reduces the prediction error of mass loss rate after several tens of epochs regardless of the type of incident heat fluxes. With the help of gradient information, the proposed CINN framework greatly reduces the computational burden of inverse modeling, which can be widely applied in the optimization of kinetic parameters for bench-scale pyrolysis.

Upgrading of Tall Fescue Grass Pyrolytic Bioliquid and Catalytic Valorization of The Biofurfural Obtained

AbstractThe production of added value products following catalytic hydrogenation reactions of bioliquids was studied. These bioliquids were obtained from the pyrolysis of raw and acid‐treated (H3PO4) Tall Fescue (Fescue arundinacea) waste. Before the pyrolytic test, the biomass samples were analyzed by a micro thermogravimetric analysis coupled with FTIR spectroscopy (TGA‐IR), which enables the chemical identification of functional groups of gaseous molecules originated by solid/gas transformations. From these results, the pyrolysis temperature was selected, and bench scale pyrolysis reactions were carried out. The pyrolysis bioliquids showed high furfural concentration, 46 and 70 % for fescue and acid washed fescue, respectively. The bioliquid with the highest furfural concentration was catalytically hydrogenated in aqueous phase. A batch reactor was employed, with Ru/C and Ru−Sn/C catalysts to produce high added value alcohols.

High-Temperature Pyrolysis for Elimination of Per- and Polyfluoroalkyl Substances (PFAS) from Biosolids

Biosolids generated as byproducts of wastewater treatment processes are widely used as fertilizer supplements to improve soil condition and ultimately agricultural products yields and quality. However, biosolids may contain toxic compounds, i.e., per- and polyfluoroalkyl substances (PFAS), which can end up in soils, groundwater, and surface water, causing adverse environmental and health effects. The purpose of this study was to investigate the application of High-Temperature Pyrolysis (HTP) treatment for biosolids management, and its efficacy in eliminating PFAS from the solid fraction. Biosolid samples were pyrolyzed at two different temperatures, 500 and 700 °C, in a continuous bench-scale pyrolysis unit. The major finding is that the treatment process at higher pyrolysis temperatures can remarkably reduce or eliminate the level of PFAS (by ~97–100 wt%) in the resulting biochar samples.

Unraveling the carbene chemistry of oxymethylene ethers: Experimental investigation and kinetic modeling of the high-temperature pyrolysis of OME-2

Oxymethylene ethers (OMEs) form an interesting family of synthetic compounds to replace fossil fuels. This alternative liquid energy carrier can contribute to a circular carbon economy when produced via carbon capture and utilization technology using renewable electricity. Despite the potential to reduce greenhouse gas and particulate matter emissions and their ideal ignition characteristics, little is known about the thermal decomposition behavior of OMEs. In this work, new insights are obtained in the pyrolysis chemistry of oxymethylene ether-2 (OME-2) and the role of carbenes by performing experiments at high temperatures (> 850 K) in a tubular quartz reactor. The used continuous bench-scale pyrolysis unit has a dedicated on-line analysis section including comprehensive two-dimensional gas chromatography (GC × GC) coupled with flame ionization detection (FID) and mass spectroscopy (MS) to identify and quantify the full product spectrum over the complete temperature range. The reactor temperature was varied between 850 and 1150 K at a fixed pressure of 0.15 MPa and residence times of 400 to 850 ms. The major products are dimethoxymethane, formaldehyde, methyl formate, methane, CO2, CO and H2. Minor intermediate compounds comprise dimethyl ether, formic anhydride, formic acid, methoxymethyl formate and methoxymethanol. The yields of compounds with carbon-carbon bonds are low since no such bonds originally occur in OME-2. Precursors of aromatic compounds and soot particles are absent in the reactor effluent. The experimental results are simulated with a new first principles-based kinetic model for pyrolysis and combustion of OME-2. This model can predict the experimental trends of major products on average within the experimental uncertainty margin of ± 10% relative for major product species. A reaction pathway and sensitivity analysis are presented to highlight the importance of the carbenes for initiation of the radical chemistry under pyrolysis conditions.

Pyrolysis of engineered beach-cast seaweed: Performances and life cycle assessment

The blooming of beach-cast seaweed has caused environmental degradation in some coastal regions. Therefore, a proper treating and utilizing method of beach-cast seaweed is demanded. This study investigated the potential of producing power or biofuel from pyrolysis of beach-cast seaweed and the effect of the ash-washing process. First, the raw and washed beach-cast seaweeds (RS and WS) were prepared. Thereafter, thermogravimetric analysis (TG), bench-scale pyrolysis experiment, process simulation, and life cycle assessment (LCA) were conducted. The TG results showed that the activation energies of thermal decomposition of the main organic contents of RS and WS were 44.23 and 58.45 kJ/mol, respectively. Three peak temperatures of 400, 500, and 600 °C were used in the bench-scale pyrolysis experiments of WS. The 600 °C case yielded the most desirable gas and liquid products. The bench-scale pyrolysis experiment of RS was conducted at 600 °C as well. Also, an LCA was conducted based on the simulation result of 600 °C pyrolysis of WS. The further process simulation and LCA results show that compare to producing liquid biofuel and syngas, a process designed for electricity production is most favored. It was estimated that treating 1 ton of dry WS can result in a negative cumulative energy demand of -2.98 GJ and carbon emissions of -790.89 kg CO2 equivalence.

Sensitivity Analysis of a Bench-Scale Pyrolysis Model for Composite Materials: A Case Study of Poly(lactic acid)/Melamine/Ammonium Polyphosphate

On the basis of a well-developed bench-scale pyrolysis model that relates material composition to flammability, this paper applied mathematical simulations to explore the model sensitivity for the prediction of fire behavior of composite materials. A pyrolysis model for poly(lactic acid) blended with melamine and ammonium polyphosphate as the reference material was selected as the case for analysis. The model input parameters for simulations include the heat of reaction, apparent activation energy, and pre-exponential factor of 15 reactions, as well as the thermal conductivity, emissivity coefficient, absorption coefficient, and density of 17 condensed-phase components. Each reaction-related or component-related parameter was adjusted from 80% of the model value to 120% with a 5% or 10% gradient. Finally, 826 simulation cases in total were calculated for analysis. Both the mass loss rate and the heat release rate of each case were calculated to characterize the sensitivity, which showed the same pattern. Finally, seven primary reactions and five key condensed-phase components with high sensitivity were identified. The predicted fire behaviors are highly related to the kinetics of the reactions between virgin components or reactions where virgin components play an important role in, including the pyrolysis of melted poly(lactic acid), the first step in the pyrolysis of melamine, the first step in the pyrolysis of ammonium polyphosphate, the reaction between melted poly(lactic acid) and melamine, the reaction between ammonium polyphosphate and melamine, and further decomposition of the generated new condensed-phase component. Particularly, the activation energy of these reactions is of sensitivity larger than 5% or 15%. The heat of decomposition of pyrolysis of melted poly(lactic acid) also showed a sensitivity of 2%–5%. The pre-exponential factor of all reactions showed a sensitivity of less than 2%, which can be ignored. Inputting the proper density is important for the prediction of fire behavior as the sensitivity is larger than 2%. The sensitivity of the milligram-scale model was also processed and compared. These simulations provided a fundamental understanding of the sensitivity of thermophysical and chemical properties and thus provide advanced insights into fire behavior modeling and new composite material design.

A Study on Pyrolysis of Pretreated Automotive Shredder Residue—Thermochemical Calculations and Experimental Work

The automotive shredder residue (ASR) is generated as an inevitable waste after the shredding process of end-of-life vehicles. Typically, the ASR ends up in a landfill in the absence of any existing processing options. The ASR comprises rubber, wood, plastics, textile, metals, and other materials, such as paint and glass (10%), which can be recycled and reused. Given these attributes, the ASR is a potential feedstock for energy production and metal recovery. In this study, ASR was first pretreated because untreated ASR (as received) is fluffy and heterogeneous and, therefore, is difficult to feed into a reactor. Subsequently, the pyrolysis process was conducted with this pretreated ASR for energy recovery. From the thermochemical calculations, an optimized temperature of 500°C was chosen for pyrolysis of the pretreated ASR to ensure that metals would not be further oxidized and polymers could be separated from the metals in the form of volatile gases, oil, and char. Bench-scale pyrolysis tests were conducted on an integrated continuous stirred tank reactor–distillation column pyrolysis system. The product gas composition had hydrogen and methane content of 30% and 26% (v/v), respectively, contributing to the heating value of the gas obtained. The pyrolysis oil was further distilled using fractional distillation apparatus for gasoline and diesel-grade products. The physicochemical characterization of the pretreated ASR pyrolysis oil and its distillates was also carried out. The thermochemical equilibrium predictions showed a similar trend with the experimental pyrolysis results. In addition, the residual char analysis indicated the presence of a significant amount of metals—silicon, titanium, aluminum, and iron. Thus, this work generated information on processing pretreated ASR for the production of fuel and insights on metal recovery that can be recovered from the residual pyrolysis char.

Study on characterization of bio-oil derived from sugarcane bagasse (Saccharum barberi) for application as biofuel

Abstract Lignocellulosic biomass especially, sugarcane bagasse Saccharum barberi sp., appears to be a more suitable material for partial substitution of transport fuel (diesel) than Saccharum officinarum sp., due to its structural similarity to transport fuel (diesel). Besides that, less research has been implemented on this type of species. Bio-oil can be implemented as biodiesel by processing it further using chemical reactions such as hydrodeoxygenation and cracking with zeolite catalyst. Hence, the purpose of this study is to determine the compatibility of pyrolytic bio-oil produced from Saccharum barberi sp. in comparison with S. officinarum sp. for use as transport fuel (diesel) in automotive applications. This purpose can be accomplished by comparing the oil’s bio-physiochemical properties for both species. The experiment is conducted on a bench-scale on which bio-oil of Saccharum barberi sp. is secured from the catalytic pyrolysis process at a temperature of 500°C and heating rate of 50°C/min with the addition of ZSM-Zeolite catalyst. Thermogravimetric analysis of Saccharum barberi sp. reveals that cellulose is more reactive than lignin, evidenced by the high percentage of weight loss at temperatures ranging from 251°C to 390°C. The high contents of carbon (40.7%) and hydrogen (6.50%), as well as slight traces of sulphur (0.08%) and nitrogen (0.85%), in bio-oil (Saccharum barberi sp.) indicate that it is conceivable to be partially used for replacement in biofuel production. Overall physiochemical properties reveal that Saccharum barberi sp. shows more potential than S. officinarum sp. Gas chromatography–mass spectrometry analysis reveals that bio-oil consists of high amounts of aromatic hydrocarbon (26.2%), phenol (14.8%) and furfural (13.0%) in comparison to S. officinarum sp. Biofuel was produced from sugarcane bagasse (Saccharum barberi sp.) in a bench-scale pyrolysis reactor at 500°C using a zeolite catalyst. Measured properties of the biofuel make it suitable for partial substitution of diesel in transport fuel.

Conversion of plastic waste into fuel oil using zeolite catalysts in a bench-scale pyrolysis reactor.

Catalytic pyrolysis of mixed plastic waste to fuel oil experiment was tested with ZSM-5 zeolite (commercial and synthesized) catalysts along with other catalysts. The ZSM-5 zeolite catalyst was effectively produced using a hydrothermal technique via metakaolin as an alumina source. The catalytic pyrolysis of different types of plastic (single and multilayer) wastes in the presence of various catalysts was tested with a bench-scale pyrolysis setup with 2 kg per batch capacity. Polyolefin based plastics (low-density polyethylene, high-density polyethylene, and polypropylene), multilayer plastics such as biaxial oriented polypropylene (BOPP), metalized biaxial oriented polypropylene layers (MET BOPP), polyethylene terephthalate (PET), metalized polyethylene terephthalate (MET/PET), polyethylene terephthalate combined polyethylene (PET/PE), and mixed plastic waste collected from the corporation sorting center were pyrolyzed in a batch pyrolysis system with 1 kg feed to determine the oil, gas and char distributions. The performances of commercial ZSM-5 and lab synthesized ZSM-5 catalysts were compared for the pyrolysis of non-recyclable plastic wastes. Other commercial catalysts including mordenite and gamma alumina were also tested for pyrolysis experiments. The gross calorific value of oil obtained from different combinations of multilayer packaging waste varied between 10 789–7156 kcal kg−1. BOPP-based plastic waste gave higher oil yield and calorific value than PET-based plastic waste. Sulfur content present in the oil from different plastic wastes was measured below the detection limit. The synthesized ZSM-5 zeolite catalyst produced a maximum oil output of 70% and corresponding gas and char of 16% and 14% for LDPE plastic. The strong acidic properties and microporous crystalline structure of the synthesized ZSM-5 catalyst enables increased cracking and isomerization, leading to an increased breakup of larger molecules to smaller molecules forming more oil yield in the pyrolysis experiments. Residual char analysis showed the maximum percentage of carbon with heavy metal concentrations (mg kg−1) in the range of viz., chromium (15.36–97.48), aluminium (1.03–2.54), cobalt (1.0–5.85), copper (115.37–213.59), lead (89.12–217.3), and nickel (21.05–175.41), respectively.

Energy- and economic-balance estimation of pyrolysis plant for fuel-gas production from plastic waste based on bench-scale plant operations

Several pyrolysis plants have been developed and commercially operated to produce fuel oil from plastic waste. By contrast, only a few examples of fuel-gas production plants have been reported. This study investigates the feasibility of fuel-gas production from plastic waste using a bench-scale pyrolysis plant by analyzing the material and energy balances of the plant. As part of a waste-to-fuel-gas project for substituting natural gas used in cogeneration equipment, this study examines the material and energy balances during operation of an externally heated rotary kiln reactor.The scale-up simulation of a 200-kg/h plant was performed based on the operation results obtained for a 2-kg/h plant using polypropylene and laminates of polypropylene with polyethylene terephthalate as feedstock. Based on the 200-kg/h plant estimates, the amount of fuel generated as fuel gas, fuel-gas consumed, and excess fuel gas used for supplying electricity to a factory using a cogeneration system equaled 3.86 × 107, 1.49 × 107, and 2.42 × 107 MJ/year, respectively, in terms of the lower heating value. The excess fuel could be used as a natural-gas substitute in cogeneration systems. In cases where a fuel-gas production system with 200-kg/h capacity costs less than USD 2,467,000, the pyrolysis-based fuel production is considered economically beneficial compared to the current treatment methods owing to the associated cost savings of up to approximately USD 177,000/year realized by ensuring substitution of 2.42 × 107 MJ/year of natural gas.

Pyrolysis of raw and anaerobically digested organic fractions of municipal solid waste: Kinetics, thermodynamics, and product characterization

• The pyrolysis performance of OFMSW and its digestate have been compared. • The E a of pseudoreactions of OFMSW are higher than those of digestate. • The pyrolysis of OFMSW yields more heavy organic fraction and less reaction water. • The application of AD can enhance the interactions among feedstock components. • The permanent gas yield of OFMSW is 8 wt% higher than that of digestate. Treating the solid residue after anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is currently a challenge. Here, pyrolysis is a promising way of recovering energy and materials from these solid residues. Thus, the objective of this study was to investigate the pyrolysis performance of these solid residues. The effect of AD on the pyrolysis of OFMSW was also studied. Thermogravimetry (TG), differential thermal analysis (DTA), and bench-scale pyrolysis experiments were performed by using OFMSW and anaerobically digested OFMSW. Mathematical deconvolution analysis (MDA), model-free methods, and model-based methods were applied to study the kinetics. Thereafter, thermodynamic parameters were estimated based on the deduced kinetic results. The char, liquid, and permanent gas products from bench-scale experiments were characterized. The pyrolysis results show that the activation energies of the pseudoreactions of OFMSW are higher than those of the corresponding pseudoreactions of digestate. Moreover, the entropy reduction for digestate is larger than that for OFMSW. The characterization results of the products from the bench-scale experiments show that the interactions among feedstock components (lipids, lignocellulose, and proteins) during pyrolysis are enhanced by the application of AD. However, the pyrolysis yields of both heavy organics and gas are inhibited by the application of AD, while the char yield shows the opposite trend.

Experimental Investigation of Fast Pyrolysis of Isoberlina doka-Derived Sawdust for Bio-Oil Production

Fast pyrolysis is considered an emerging technology for biomass conversion into liquid oil. In this paper, the conversion of waste from Isoberlina doka tree processing into bio-oil using a bench-scale fixed bed reactor with a fluidized behavior within the bed zone has been investigated at temperatures of 400–500 °C and particle size ranges of < 0.5 and 0.5–1 mm. Reactor with the total height of 140 mm consisting of three zones with gas inlet diameter of 10 mm, reaction zone diameter of 70 mm, outlet diameter of 15 mm and a coupled detachable inlet with a diameter 15 mm for biomass loading was used for experimentation. Nitrogen was used as the carrier gas, and the products were biochar, bio-oil and non-condensable gas. Thermogravimetric and derivative thermal analysis (TG/DTA) was carried out in order to understand the thermal behavior of wood particles. Bio-oil produced was analyzed using the gas chromatography mass spectrometry and the Fourier transform infra-red spectrophotometry methodologies. TG/DTA analysis revealed an initial 30.639% mass loss which correlates to hardwood thermal characteristics. Bio-oil yield from bench-scale pyrolysis increased with increasing temperature. A maximum bio-oil yield of 49.84 wt % was observed at the particle size range of 0.5–1 mm, bed temperature of 500 °C and time of 30 min. Volatile generation was at the peak of 54.54% (0.002655 kg/min). However, changes in the chemical composition and functional groups of bio-oil with temperature of production suited it for different usage purposes.

A comparative production and characterisation of fast pyrolysis bio-oil from Populus and Spruce woods

This study focuses on the production and characterisation of fast pyrolysis bio-oil from hardwood (Populus) and softwood (Spruce) using a bench-scale pyrolysis reactor at two different temperatures. In this study, a mixed solvent extraction method with different polarities was developed to extract different components of bio-crude oil into three fractions. The obtained fractions were characterized by using gas chromatography and mass spectrometry (GC-MS). The effect of temperature on the production of bio-oil and on the chemical distribution in bio-oil was examined. The maximum bio-oil yield (71.20%) was obtained at 873 K for bio-oil produced from softwood (Spruce). In contrast, at a temperature of 773 K, the bio-oil yields were 62.50% and 65.40% for bio-oil obtained from hardwood (Populus) and softwood (Spruce) respectively. More phenolic compounds were extracted at a temperature of 773 K for bio-oil derived from softwood (Spruce) whereas the bio-oil obtained from hardwood (Populus) produced mostly furans, acids and sugar compounds at this temperature. For both types of bio-oil, a wide variety of chemical groups were identified at a temperature of 873 K in comparison to 773 K.

Effects of copper oxide and sulfuric acid on the pyrolysis behavior of ammonium nitrate under thermal radiation experiments

Statistics have indicated that industrial accidents of ammonium nitrate were primarily caused by uncontrolled external fires where heating was dominantly controlled by radiation, and yet existing studies at milligram scale cannot fully simulate the real fire scenarios. To explore the pyrolysis behavior in typical fires, this study conducted thermal radiation experiments using pure ammonium nitrate, and its mixtures with copper oxide and sulfuric acid. Different from the pyrolysis process identified in milligram scale tests, the bench-scale pyrolysis of ammonium nitrate under radiation consisted of four stages. Pyrolysis structure model of each stage was built to reveal the differences in dominated thermal behavior. Results indicated that two additives had different thermo-chemical effects on pyrolysis of ammonium nitrate. Sulfuric acid accelerated the reaction rate of each stage by generating catalytic nitric acid; copper oxide reduced the number of reaction stages into three via surface absorptions. The time and mass loss rate of different stages were determined. Recommendations on effective emergency response were made to prevent the transition of slow decomposition into fast decomposition, and thus to intervene the fire-induced domino effect of ammonium nitrate. This study helps to understand the pyrolysis behavior of ammonium nitrate under fire exposure, and provides insights for pyrolysis modeling and firefighting in industry of interest.

Pyrolysis performance of peat moss: A simultaneous in-situ thermal analysis and bench-scale experimental study

Peat moss in drained peatlands has become a non-negligible source of greenhouse gases (GHG) emission. Pyrolysis is a potential technique to convert carbon-emitting peat moss to carbon-storage materials. This work investigates the behavior of peat moss pyrolysis by a combined in-situ thermal analysis and bench-scale pyrolysis experiment methodology. The simultaneous thermal analyzer, which provides the simultaneous TG/DTA analysis, was employed to reveal the thermal decomposition behavior of peat moss. The samples were heated up to 900 °C with different heating rates of 10, 15, and 20 °C/min. Thereafter, pyrolysis experiments with peak temperatures of 450, 500, 550 and 600 °C were performed in a bench-scale pyrolyzer. It was found that there are four main stages and two micro stages of mass loss during peat moss pyrolysis from room temperature to 900 °C. Also, kinetic parameters were calculated based on the results of TG and DTG by the Kissinger-Akahira-Sunose (KAS) method and the Coats-Redfern (CR) method. In the bench-scale pyrolysis experiments, four phases, i.e., char, tar, aqueous phase, and gas, were obtained and characterized. The carbon distribution and the GHG emission from peat moss pyrolysis were determined.

Insights into pyrolysis characteristics of Brazilian high-ash sewage sludges using thermogravimetric analysis and bench-scale experiments with GC-MS to evaluate their bioenergy potential

This paper is the first comprehensive report about the renewable fuels produced from the pyrolytic conversion of anaerobic and aerobic Brazilian high-ash sewage sludges. The study was divided into three steps: (1) an in-deep evaluation of physicochemical characteristics of both sewage sludges; (2) thermogravimetric analysis under inert conditions for determining bench-scale pyrolysis conditions; (3) characterization of volatile pyrolytic products from fixed bed reactor using GC/MS analysis. The anaerobic and aerobic sewage sludges present substantial high heating values and high contents of ash and sulfur, which are adverse properties for solid fuels. Regarding the pyrolytic behavior, the sewage sludge samples presented a two-step thermal decomposition process. The bio-oil produced from pyrolysis indicates that the high-ash sewage sludges are a source of high value-added chemicals, such as aliphatic and monoaromatic hydrocarbons. In addition, the pyrolysis can promote the production of a hydrogen-rich syngas for thermal boilers or engines use. In this research, it was demonstrated that the pyrolysis process of Brazilian high-ash sewage sludge can be applied for the production of useful biofuels - as bio-oil and bio-syngas - also adding value to this waste, thus contributing to the establishment of renewable source of bioenergy.

Validation of pyrolysis model in transient heating scenarios and diverse spectral boundary conditions

This study aims to provide a robust validation to the condensed-phase pyrolysis model approach used in the FireFOAM CFD code. Firstly, bench-scale pyrolysis tests were conducted for two engineering wood products (EWPs), namely plywood and medium density fiberboard (MDF), at three constant heat flux levels. These tests were used to derive model-effective material properties via inverse modeling and optimization approaches. For MDF, a better model fit was obtained when the virgin material density was allowed to vary along its thickness, which is consistent with its known anisotropic nature. Next, three test cases were developed for the purpose of pyrolysis model validation by subjecting the EWPs to fire-relevant dynamic heating scenarios. In two tests, the materials were exposed to transient heating conditions where the heat flux to the materials increased over the duration of pyrolysis. In the remaining test, the spectral emissivity boundary condition of the sample material was altered significantly. Very good agreement was observed between the validation experimental data and the model predictions for all three scenarios. The validation studies provide confidence that the model-effective material properties, determined using inverse modeling and optimization for constant heating conditions, can be confidently applied to fire-relevant dynamic heating scenarios and boundary conditions.

Development of a pyrolysis model for an intumescent flame retardant system: Poly(lactic acid) blended with melamine and ammonium polyphosphate

A pyrolysis model capable of predicting materials' fire behavior as a function of concentration was developed for an intumescent flame retardant system: poly(lactic acid) (PLA) blended with melamine (MEL) and ammonium polyphosphate (APP). The model was developed through inverse analysis of data obtained from bench-scale pyrolysis experiments wherein a 0.07-m-diameter disk-shaped sample was exposed to well-defined radiant heating in an anaerobic environment. Sample back surface temperature, sample shape profile and burning rate were measured simultaneously. A numerical pyrolysis modeling framework, ThermaKin2Ds, and a previously developed semi-global thermal decomposition reaction mechanism were employed in the inverse analysis to determine material properties that define the heat and mass transport inside the pyrolyzing solids. The final pyrolysis model was found to predict materials' fire behavior for a variety of thermal exposures and material compositions. The model construction process revealed that a reduction in gas transfer coefficients helped to reproduce certain features of the burning rates profiles. Idealized cone calorimetry scenarios were simulated to study the influence of additives on materials’ fire behavior, and the results demonstrated that the blend with 5 wt% MEL and 25 wt% APP was found to be the most effective system with a 69% reduction in the average heat release rate comparing to that of PLA. A similar significant reduction has been reported in the literature, supporting the accuracy of this model. This work demonstrates a methodology that enables intelligent design of intumescent flame retardant materials tailored for specific applications, where low flammability is required.