Tar Production Research Articles

Torrefaction integrated with steam gasification of agricultural biomass wastes for enhancing tar reduction and hydrogen-rich syngas production

Steam gasification is considered as a promising technology for conversion of various biomass wastes to valuable hydrogen (H2)-rich gas products that can be applied for the sustainable production of green hydrogen and methanol. However, some inevitable problems such as high tar content and low cold gas efficiency greatly hinder its broad application. Torrefaction has been widely employed for upgrading low-rank biomass sources that favors the follow-up gasification process, resulting in low tar yield and high syngas yield. Torrefied biomass usually shows higher energy density, improved grindability characteristics, and lower O/C and H/C ratios. This research work studies the effect of torrefaction on steam gasification of corncob (CC) and rice husk (RH). The mechanisms of biomass torrefaction integrated with steam gasification are also given. Biomass torrefied at a relatively high temperature (280 °C) is more efficient to extract the oxygenated volatiles, reducing the generation of tar and particulate matters during the gasification process. The increase of torrefaction temperature resulted in an increase of H2 yield and a decrease of CO yield, corresponding to an increase of H2/CO ratio. Particularly, the H2 yield in the CC-derived syngas increased from 6.38 mmol/g (raw) to 12.01 mmol/g (280 °C), and the H2 yield in the RH-derived syngas increased from 4.33 mmol/g (raw) to 12.97 mmol/g (280 °C). Steam gasification of RH torrefied at 280 °C achieved a maximum H2/CO ratio of 2.84. After torrefaction of CC and BB at 280 °C, the tar yield of steam gasification was below 1% [gasification temperature: 800 °C, mass ratio of steam to biomass (S/B): 1]. In general, the torrefaction pretreatment of biomass at relatively high temperatures (i.e., 280 °C) favors the steam gasification process under an appropriate S/B (i.e., 1) in terms of improving the syngas quality and reducing the tar production.

Detailed modelling of a double fluidised bed steam gasifier processing woody biomass and solid recovered fuel mixtures

Abstract Double fluidized bed gasification is based on the circulation of an inert bed between two reaction sections: the gasification reactor, where a solid feedstock, generally biomass. is converted into a syngas by steam or air oxidation; the combustor or riser, where residual char from the thermal decomposition of the feedstock is oxidized by air (in some cases with additional fuel) to provide the energy contribution for the gasification reactions and ensure autothermal operation of the system. In this work, detailed modelling of a dual fluidized bed steam gasification reactor is performed in Aspen Plus by incorporating: (1) gas, char and tar production during thermal decomposition of the feedstock according to experimental correlations developed and taken from the literature, (2) heterogeneous and homogeneous reaction kinetics in the gasifier bed and in the freeboard. The model has been validated by comparison with experimental results on different mixtures containing solid recovered fuels and woody biomass. The model is quite accurate in predicting the gas products composition for different feedstocks mixtures (root mean square error of 12% for CO, CO2, H2 and CH4) and enables coupling with different downstream liquid fuels synthesis processes (synthetic natural gas, methanol, dimethyl-ether, Fischer-Tropsch products etc.).

Quantitative Analysis of Wood Tar Production Efficiency of Selected Wood Species in Sierra Leone

Quantitative Analysis of Wood Tar Production Efficiency of Selected Wood Species in Sierra Leone

Kinetic characteristics and product distribution of tar-rich coal in-situ underground pyrolysis: Influence of heterogeneous coal seam

Tar-rich coal contains more hydrogen-rich structures such as aliphatic side chains and bridge bonds, which is a good raw material for coal to oil. In-situ underground pyrolysis of tar-rich coal has significant advantages such as environmental friendliness and high safety factor; it is an efficient, clean coal utilization technology. Due to the influence of geological structure and other factors in the formation process, underground coal seam was often heterogeneous, generally accompanied by coal gangue interlayers. Due to the coal gangue being relatively dense and has poor thermal conductivity, it is also rich in metal oxides, it would inevitably affect the pyrolysis characteristics and product distribution during the pyrolysis process of heterogeneous tar-rich coal seam. The pyrolysis characteristics of heterogeneous tar-rich coal seam with different positions and layers of coal gangue interlayer were investigated by the thermogravimetric analyzer, and related kinetic parameters were obtained by the distributed activation energy model (DAEM). Based on the fixed bed tube furnace reactor, the pyrolysis experiments of heterogeneous tar-rich coal seam with different positions and layers of coal gangue interlayer were also carried out, and the pyrolysis products were characterized and analyzed. The thermogravimetric results showed that in the pyrolysis process of heterogeneous tar-rich coal seam, the initial pyrolysis temperature and the temperature corresponding to the maximum weight loss rate shifted to the higher temperature range, and the pyrolysis characteristic index decreased significantly. Under the same conditions, the corresponding pyrolysis characteristic indexes of the upper coal gangue interlayer and 4 layers of coal gangue interlayer were lower, which were 11.69 (10−8·%·min−1·℃−3) and 11.65 (10−8·%·min−1·℃−3), respectively. Compared with homogeneous tar-rich coal seam, pyrolysis activation energies of heterogeneous coal seam generally showed the decreasing trend. Under the conditions of the upper part containing coal gangue interlayer and the upper-and-lower parts containing coal gangue interlayer, the pyrolysis activation energies were higher due to the hindrance of the cover layer of coal gangue to the volatile release, which were 555.88 kJ·mol−1 and 546.66 kJ·mol−1 respectively. The results of fixed bed pyrolysis experiments showed that compared with homogeneous tar-rich coal seam, the tar yield obtained was reduced, the degree of tar lightening was significantly improved, and the proportion of lighter tar was up to 70.00 wt%. The contents of aromatic hydrocarbons and phenolic compounds in tar increased, the contents of aliphatic hydrocarbons and oxygenated compounds decreased significantly, and the maximum reductions were nearly 4.50 wt% and 6.50 wt%, respectively. The gas yield increased, the proportions of H2 and CO2 in the gas increased, and the proportions of CO and CH4 decreased to varying degrees. The tar yields were lower under the conditions of upper gangue and 4 layers gangue, which were 6.53 wt% and 5.81 wt%, respectively, and the degrees of tar lightening were also more significant. From the relationship between pyrolysis characteristic parameters and tar properties of heterogeneous tar-rich coal seam pyrolysis, it was found that the existence of coal gangue interlayer was not conducive to the tar production, but it could promote the lightening of tar and improve the tar quality. Exploring the kinetic characteristics and pyrolysis product distribution of heterogeneous tar-rich coal seam could provide theoretical guidance for the site selection of in-situ underground pyrolysis engineering and the well arrangement.

TG-FTIR-Py-GCMS analysis and catalytic pyrolysis mechanism of textile waste by red mud catalyst for liquid fuel production

The substantial generation of textile waste (TW) and red mud (RM) has resulted in significant resource wastage and environmental challenges. Co-utilization technology of solid waste is an effective approach to improve waste utilization efficiency. In this study, RM catalytic pyrolysis experiments of TW were conducted using TG-FTIR and Py-GC–MS for liquid fuel production, and TW and RM were recycled simultaneously. At the optimal experimental conditions (temperature of 600 °C and feed catalyst ratio of 2:1), the tar yield and higher heating value (HHV) of TW pyrolysis catalyzed by RM were 73.43 wt% and 32.34 kJ/g, respectively. Additionally, experiments on the pyrolysis of various TW types revealed that LDPE and PP are suitable for tar production, while cotton, nylon, and PET are more suitable as feedstock for syngas production. The RM catalytic pyrolysis mechanism of textile waste is that Fe2O3 in RM exhibits significant catalytic activity in enhancing tar and syngas yields. However, during the catalytic process, Fe2O3 undergoes reduction to Fe3O4, resulting in diminished catalytic performance of the RM. After five cycles of use, the RM essentially lost its catalytic activity due to the accumulation of char and tar. All experimental findings of this study could offer an effective guideline for TW recycle and promoting RM utilization toward the waste-to-energy circular economy.

Numerical investigation to predict the impact of pre-heated air on the tar formation of cocoa pod husk gasification in a fixed bed downdraft gasifier

Tar production is a critical aspect of gasification thermochemistry, and it hinders the widening of biofuel utilisation in several applications. Both the gasifier configuration and the operating conditions influence the quantity of tar in PG. Since temperature plays a major role, this study examines the performance parameters of a gasifier across a spectrum of input air temperatures, from 27 to 627 °C, utilising computational fluid dynamics with species transport and porous media models. Since the deviation of numerical predictions from experimental results is within 10 %, the model's validity is confirmed. CO and H2 gas production increased from 19.23 % to 27.12 % and 9.23 %–16.2 %, respectively, over the tested air temperature range; however, the variation in methane content was not significant. Furthermore, the higher heating values of PG and cold gas efficiency were found to be 5–6.8 MJ/Nm3 and 65–69 %, respectively. The study also investigates reaction rates for gasification, combustion, and volatiles' breakdown under various operating conditions. Among the tar species studied, benzene is the most concentrated at 1.6 g/Nm3, followed by toluene at 0.9 g/Nm3, with naphthalene and phenol present in comparatively smaller amounts. Furthermore, the research indicates that an appropriate temperature of gasifying medium can control tar in PG.

Characteristics and kinetics of in-situ catalytic cracking of biomass tar in a micro dual bed reactor

This research introduces a novel micro dual bed reactor, combining rapid pyrolysis in a top-down with a fluidized bed for biomass tar catalytic cracking assessment. The study initially examines the impact of reactor zones on biomass pyrolysis, followed by an exploration of thermal and catalytic cracking behaviors of in-situ biomass tars using three fluidizing media. It delves into the generation of cracking gas and tar cracking reaction kinetics, based on the evolutionary trends of the gas. The process involves two distinct stages (S1 and S2). In S1, olivine shows the highest tar conversion rates at 650 °C and 750 °C, while char peaks at 850 °C. In S2, char leads in conversion rate and reaction time, with a preference for CO and H2. Tar conversion rates at high temperatures follow the order char > olivine > sand, and reaction times vary as olivine > sand > char. Temperature affects tar cracking rates due to thermal and catalytic effects interplay. This study applies an integral method to solve the kinetics under varying conditions, providing insights into tar behaviors during both thermal and catalytic cracking. These findings support designing and optimizing tar removal units in biomass gasification, potentially reducing tar production and enhancing gas quality.

Co-pyrolysis characterization of pre-oxidized lignite and corn stover

In this paper, low-rank lignite and corn stover were pre-oxidized at 200 °C with varying oxygen concentrations (0 %, 6 %, 21 %). The study investigated the effects of pre-oxidation on the physical and chemical properties of lignite and stover, including composition, functional group structure, etc. Subsequently, co-pyrolysis experiments were conducted on the pre-oxidized lignite and stover at 700 °C. The study examined the characteristics of the co-pyrolysis of lignite and corn stover under different oxygen concentrations. The results showed that pre-oxidation could effectively increase the content of fixed carbon in the raw materials, elevate the content of carbonyl and carboxyl groups in the raw materials, and reduce the number of aliphatic hydrocarbon side chains as well as hydroxyl groups. The degree of aromatization of the co-pyrolysis char produced from pre-oxidized lignite and corn stover was enhanced. The 6 % O2 pre-oxidation promoted the pyrolysis degree of the raw materials and intensified the progression of the reaction. The CO2 content of the co-pyrolysis tar was at a minimum of 23.028 % with 0 % O2, and the gas had a maximum calorific value of 11.651 MJ∙Nm−3 at this point. Pre-oxidation had an inhibitory effect on the production of co-pyrolysis tar, and the inhibitory effect became more pronounced with higher concentrations of O2. The higher the oxygen concentration, the more pronounced the inhibition. The addition of oxygen promotes the generation of phenols and ketones in the tar, reducing the content of acids and aldehydes. This improves the quality of the tar but also results in a reduction of aromatic hydrocarbons to some extent.

Testing non-destructive spectrometric methods for the identification and distinction of archaeological pine wood tar and birch bark tar

Archaeological findings prove the appearance and use of birch bark tar since the Middle Palaeolithic. The production and use of birch bark tar and pine wood tar has overlapped since at least the late Neolithic, but probably for much longer. The reliable chemical identification of such archaeological tar residues can offer valuable insights into, for example, ancient technical complexity, trade and culture. In this context, the scarcity of these mainly organic residue findings in the archaeological record bears the need for non-destructive analytical tools. However, there is currently no systematic proposed way for this purpose. We aim here to verify the organic nature and test the reliability of the identification of archaeological pine wood tar and birch bark tar with a combination of SEM-EDS, FTIR microspectroscopy in reflectance mode and XRD. We examined a set of experimental adhesive replicas of pine tar and birch tar in pristine form, but also after a three-year-long weathering experiment. Additionally, we studied a set of archaeological samples, consisting of Mesolithic bone/antler points with adhering hafting residues, form the Dutch North Sea. This research shows that degradation negatively influences the reliable verification and identification of the organic residue constituents significantly. SEM-EDS as a starting point of analysis verifies the residue’s organic nature, but it cannot be used to identify birch or pine tar. XRD can identify crystalline additives in the adhesive mixture, like ochre and wax, as well as phases related to the artefact’s environment of burial and provenance. Micro-FTIR is also capable of verifying the organic matter of the residue constituents. The differentiation of birch and pine tars is hindered by vibrational modes occurring in neighbouring wavenumbers for both tars, and by the limited research on degradation markers indicative of thermal treatment to prove tar production. Until reference collections also account for degradation and include a wide variety of adhesives, results of FTIR collected in reflectance mode are best treated with some caution.

Experimental and numerical investigation on the heat and mass transfer performance of tar rich coal in-situ pyrolysis

On ground experiments are conducted firstly to simulate the multi-physics underground pyrolysis of tar rich coal and find out the kinetic parameters of the reaction. And then multi-physics simulation is performed by coupling heat transfer, fluid flow and chemical reactions. Three pyrolysis models are compared and it’s found that the convective flow of heat carrier in coal seam plays an important role in heat transfer although the flow velocity is low. Then the effects of permeability, inlet mass flow rate on heat and mass transfer are investigated for two geometric models with homogeneous and inhomogeneous permeability. It’s found that increasing the permeability is beneficial for fast production of tar. For the homogeneous permeability model, the pyrolysis reaction can be completed in only 140 days when the permeability is 1000 md while for the non-homogeneous permeability model, increasing the inlet mass flow rate can improve the heat and mass transfer performance only in the early stage when the pyrolysis occurs mainly in the fractured zone with higher permeability. The pyrolysis reaction time when the inlet mass flow rate is 0.174 kg/s is 22 days shorter than that of 0.054 kg/s. But in the later stage the inlet mass flow rate has little effect on the reaction rate and brings about a higher pressure drop. The pyrolysis under different well patterns is also compared and the results indicate that four-well heating and six-well heating modes can improve the uniformity and the reaction conversion rate with the same total inlet mass flow rate during the same time. For the six-well heating mode, the pyrolysis reaction can be completed in about 100 days, which is 60 days shorter than the single-well heating mode.

Optimization and Techno-Economic analysis of catalytic gasification of wheat straw biomass using ASPEN PLUS model

Biomass gasification efficiently produces heat, electricity, and power. However, removing harmful contaminants from raw syngas is crucial. Tar production is a challenge due to blockage, plugging, and corrosion. Tar steam reforming (TSR) is the most promising technique, converting high molecular weight hydrocarbons into CO, CO2, H2, and CH4. In this study, a model of biomass gasification using wheat straw as biomass feedstock has been developed using Aspen Plus. The gasification flow sheet encompasses gasification, catalytic filter candle, gas cleaning, impurity removal reactor, separator, and subsequent sorbent reactors. Ni-based catalysts with Ni ratios (5%, 10%, and 15%) are used to simulate TSR reactions. Results show that the 15% Ni-Co-Al2O3 catalyst outperforms the 10% and 5% Ni-Co-Al2O3 catalysts. This study explores the impact of temperature, catalyst loadings, and steam-to-carbon (S/C) ratios on toluene conversion and hydrogen yield in catalytic steam reforming, along with temperature, steam-to-biomass ratios, and equivalence ratio on syngas fraction in gasification. It includes a techno-economic analysis of wheat straw gasification to improve syngas energy through efficient tar conversion.

Numerical study on kinetics of tar production and mechanism of benzene formation during corn straw gasification

Tar production is a key factor hindering the industrialization of biomass gasification technology. Understanding the mechanisms of tar formation can help predict and reduce tar yield. A gasification model was proposed to investigate the effects of oxygen ratio (OR) and temperature on products formation. Its accuracy was validated using experimental data. The relative content of PAHs from corn straw gasification decreased from 95 % to 53 % with OR and temperature increasing, indicating PAHs relative content could be decreased by increasing OR and temperature. The concentrations of phenanthrene from cellulose and corn straw gasification at 900 °C were 0.85 and 378 ppm, separately. The concentrations of pyrene were 52 and 558 ppm, respectively. The content of PAHs from cellulose gasification was much less than that from corn straw gasification. However, the contribution of cellulose to PAHs formation increased with temperature increasing. Furthermore, the mechanism of benzene formation was analyzed qualitatively and quantitatively. C2H2, C3H3, and C4H6 were main precursors and exhibited a considerable role in benzene formation. H, OH, CH3, and C6H5 were the key radicals. The analysis results indicated that CH3→C2H2→C3H3→benzene and C2H3/C2H4→C4H6→n-C4H5→benzene were two main paths for benzene formation during corn straw gasification.

Influence of Temperature and Blending Ratio on Product Yield for Co-gasification of Torrefied Palm Kernel Shell (TPKS) and Low-Density Polyethylene (LDPE)

This study investigated the product yields produced from the co-gasification of torrefied palm kernel shell (TPKS) and low-density polyethylene (LDPE). Prior co-gasification, PKS was undergo pre-treatment process at different temperature. The optimum parameter for torrefaction was found at 250 oC for 60 min reaction time with 4.89 wt.% moisture content and 10.48 wt.% fixed carbon. Thus, the result indicated that TPKS a suitable fuel feedstock for further thermal conversion. Then, TPKS and LDPE were gasified at different temperature and blending ratio for 60 min reaction time. The results showed that, Co-gasification is significantly influenced by temperature. A higher gasification temperature improves the gasification rate by increasing carbon conversion. By varying temperature from 600 to 1000 oC, the tar production dropped significantly from 49.61 to 35.03 wt.%, while the gas yield grew significantly from 25.88 to 45.94 wt.%. However, as temperature increased from 800 to 1000 oC, tar yield increased from 26.58 to 35.03 wt.%. Meanwhile, char yield decreased from 24.50 wt.% to 19.02 wt.% when the temperature from 600 to 1000 oC. For the effect of blending ratio, through blending of TPKS and LDPE, the gas and char yield increase, while tar decrease with increase torrefied TPKS ratioAdditionally, it was found that the highest gas yield with low tar and char yield was obtained from the co-gasification of TPKS and LDPE at 50:50 blending ratios produce the than another blending ratio. Therefore, based on the effect of temperature and blending ratio on product yield shows that the optimum parameter to produce maximum gas yield with minimum tar and char yield are at 50:50 (TPKS: LDPE) blending ratio at 800oC for 60 minutes reaction time. The gas analysis exhibited in increasing H2 composition when the reaction time increase for TPKS: LDPEcompared than UnPKS:LDPE.

Differences in birch tar composition are explained by adhesive function in the central European Iron Age.

Birch bark tar is the most widely documented adhesive in prehistoric Europe. More recent periods attest to a diversification in terms of the materials used as adhesives and their application. Some studies have shown that conifer resins and beeswax were added to produce compound adhesives. For the Iron Age, no comparative large-scale studies have been conducted to provide a wider perspective on adhesive technologies. To address this issue, we identify adhesive substances from the Iron Age in north-eastern France. We applied organic residue analysis to 65 samples from 16 archaeological sites. This included residues adhering to ceramics, from vessel surface coatings, repaired ceramics, vessel contents, and adhesive lumps. Our findings show that, even during the Iron Age in north-eastern France, birch bark tar is one of the best-preserved adhesive substances, used for at least 400 years. To a lesser extent, Pinaceae resin and beeswax were also identified. Through statistical analyses, we show that molecular composition differs in samples, correlating with adhesive function. This has implications for our understanding of birch bark tar production, processing and mode of use during the Iron Age in France and beyond.

Two-stage pyrolysis for effective tobacco stem utilization and tar reduction

Tobacco stem (TS) is a waste product of tobacco industry that cannot be directly disposed of due to regulatory concerns. This study explored a two-stage pyrolysis for modifying the TS structure, rendering it unusable for tobacco products, while preserving potassium and nitrogen in the char for agricultural use as fertilizer. Furthermore, the study aimed to minimize the production of harmful tar by in-situ converting heavy volatiles into gases. The effects of first-stage pyrolysis temperature (400 – 650 °C), second-stage temperature (600 – 800 °C) and various catalysts (β(60 H), HY, HZSM-5 and TiO2) on product distributions and properties were studied. Elemental analysis, FTIR, XRF and ICP-MS were employed to assess the retention of potassium and nitrogen in the char. The results show that under optimal conditions (450 ℃ for pyrolysis and 800 ℃ for cracking), a 40.3 wt% char yield with 93.0 wt% potassium and 50.3 wt% nitrogen retention, 1.8 wt% tar yield and 34.6 wt% gas yield were achieved. The two-stage pyrolysis established a staged temperature profile within the reactor, decoupling the “primary pyrolysis” of TS from the “secondary reaction” of volatiles. In comparison to one-stage pyrolysis, this approach reduced tar production by 89.9% and increased gas production by 51.6%. The use of HZSM-5 and HY catalysts further reduced tar yields by up to 30.9%. This innovative process altered TS structure, retained crucial nutrients in the char, significantly reduced tar content, and mitigated harmful substances such as nicotine and phenols, offering a sustainable solution for tobacco waste management.

Analysis of the Solar Pyrolysis of a Walnut Shell: Insights into the Thermal Behavior of Biomaterials

The state of Sonora, Mexico, stands as one of the leading producers of pecan nuts in the country, which are commercialized without shells, leaving behind this unused residue. Additionally, this region has abundant solar resources, as shown by its high levels of direct normal irradiance (DNI). This study contributes to research efforts aimed at achieving a synergy between concentrated solar energy technology and biomass pyrolysis processes, with the idea of using the advantages of organic waste to reduce greenhouse gas emissions and avoiding the combustion of conventional pyrolysis through the concentration of solar thermal energy. The objective of this study is to pioneer a new experimental analysis methodology in research on solar pyrolysis reactors. The two main features of this new methodology are, firstly, the comparison of temperature profiles during the heating of inert and reactive materials and, secondly, the analysis of heating rates. This facilitated a better interpretation of the observed phenomenon. The methodology encompasses two different thermal experiments: (A) the pyrolysis of pecan shells and (B) the heating–cooling process of the biochar produced in experiment (A). Additionally, an experiment involving the heating of volcanic stone is presented, which reveals the temperature profiles of an inert material and serves as a comparative reference with experiment (B). In this experimental study, 50 g of pecan shells were subjected to pyrolysis within a cylindrical stainless-steel reactor with a volume of 156 cm3, heated by concentrated radiation from a solar simulator. Three different heat fluxes were applied (234, 482, and 725 W), resulting in maximum reaction temperatures of 382, 498, and 674 °C, respectively. Pyrolysis gas analyses (H2, CO, CO2, and CH4) and characterization of the obtained biochar were conducted. The analysis of heating rates, both for biochar heating and biomass pyrolysis, facilitated the identification, differentiation, and interpretation of processes such as moisture evaporation, tar production endpoint, cellulosic material pyrolysis, and lignin degradation. This analysis proved to be a valuable tool as it revealed heating and cooling patterns that were not previously identified. The potential implications of this tool would be associated with improvements in the design and operation protocols of solar reactors.

Complicating the debate: Evaluating the potential of gas-chromatography-mass spectrometry for differentiating prehistoric aceramic tar production techniques

Birch bark tar was used extensively throughout human history. While later ceramic-based production technologies are known, prehistoric aceramic techniques leave little to no archaeological evidence. Experimental tar production attempts to fill this gap and suggest potential techniques. However, their archaeological relevance is unclear. Through an in-depth biomolecular analysis using Gas Chromatography-Mass Spectrometry, this study attempts to differentiate tars produced using four experimental aceramic techniques: condensation, ash mound, pit roll, and raised structure. In doing so we publish the largest collection of GC-MS results of aceramic birch tars. The results show that pentacyclic triterpenoids, characteristic of birch bark, vary between the production techniques in relation to heating exposure and perhaps the tar collection method. This allows for a tentative identification of tars produced through the condensation and ash mound techniques, which were formed consistently using short periods of heating and collected systematically by scraping. In contrast, tars produced using the pit roll and raised structure techniques do not have consistent molecular signatures. Despite the partial success of Gas Chromatography-Mass Spectrometry, the archaeological relevance is questioned because this technique is only applicable to samples from optimum lipid preservation conditions when a high number of pentacyclic triterpenoids are preserved. Therefore, using Gas Chromatography-Mass Spectrometry to determine the transformation methods of organics, like birch bark, may not be an appropriate standalone technique to fairly discuss the technological capabilities of past populations.

Pyrolysis characteristics and product distribution of low-rank coal with heat-carrying particles adopting TG-FTIR and a novel self-mixing down tube reactor

A novel self-mixing down tube (SDT) pyrolyzer has been developed, which can separate the heat carrying particles preheated in the fluidized bed from the coal, and the two can be mixed through a specific structure to instantly heat the coal particles to a predetermined temperature. The present study investigated the pyrolysis behavior of low-rank coal with hot silica sand heat-carrying particles adopting TG-FTIR. Identifies optimal conditions for maximum tar production in a laboratory-scale SDT using a significantly larger range of coal feed rates (4 kg/h). An increase in the degree of coal metamorphism increased the initial temperature and the yield of char. The tar yield from Huolinhe lignite coal (6.56 %) and Daliuta bituminous coal (7.48 %) showing a trend of first increased and then decreased with elevating the operating temperature and optimal temperature at 520 °C, respectively. The effect of coal particle size on tar yield mainly comes from the different degrees of secondary cracking caused by contact with solid heat-carrying particles as well as the differences in the content of macerals. GC‒MS spectra of tar and deposited carbon on silica sand indicated that heavy tar can easily deposit on the surface of sand and form char through polymerization reactions.

Feasibility of Efficient Pyrolysis of Wood Chips and its Product Yield in Developing Countries

This paper is about the feasibility of combustibles gases like methane, ethane and carbon monoxide production from wood pyrolysis. This first laboratory experimental stage objective was to see what products can be obtained from wood pyrolysis in absence of oxygen and presence of nitrogen. The effect of temperature on the product yields was investigated. Products were characterized using gas-chromatography. We found that products of wood pyrolysis for temperatures of 700, 800, 900, 1000 and 1100°C were char, CO2 and combustibles gases like CH4, C2H2, CO and tar. NH3 was not found in the produced gases.
 In our study, condensable gases were not recovered and quantified. A gas condenser would have been necessary inserted for this purpose at the outlet of the pyrolysis reactor before routing the gases to the mass spetrograph. This study show that char production decrease from 17.08% at 700°C on the weight basis to 12.95% at 1100°C. Gases and tar production decrease, going from 82.92% at 700 °C on the weight basis to 87.05% at 1100°C. Carbone dioxide production also increase with temperature. It is the biggest part of produced gases of the wood pyrolysis gases representing an average weight proportion of 6.99% of the initial wood. Carbone monoxide yield is almost constant, around 1.6% at 800, 900 and 1000°C thought its yield at 700°C was found slightly higher accounting for 2.29% weight of the initial wood. Ethylene (C2H4) is only produced in small amount compared to others combustibles gases like methane and carbon monoxide. Its proportion which was observed almost constant, around 0.14% on the weight basis in respect to the initial wood chips weight from 700 to 900°C dropped to 0.02% at 1000°C. Methane (CH4) is produced in weight basis proportions of 2.55% which remain almost constant from 700 to 1000°C.

Effect of moisture on gasification of hydrochar derived from real-MSW

Municipal solid waste (MSW) fuel quality could improve through hydrothermal carbonization by reducing the water content, eliminating chlorine, and increasing energy density. This study proposed a method of in-situ steam gasification to produce gas and tar to improve energy recovery efficiency from hydrochar. The thermogravimetric analysis was used to investigate the essential pyrolytic characteristics of the hydrochar. The activation energy (Ea) first decreased and then increased when hydrochar was pyrolyzed under an N2 atmosphere. The steam automatically generated by the wet hydrochar would enhance the steam reforming reaction and the water-gas transfer reaction to develop in the direction of hydrogen production. Meanwhile, excess steam consumes more energy, causing reactor temperatures to drop, thereby reducing the total gas production and H2 production. These discoveries might offer comprehensive information on the production of syngas and poly-aromatic tar from hydrochar gasification, which would support the cost-effective use of MSW.