Maximum Tar Yield Research Articles

Comprehensive kinetic modeling and product distribution for pyrolysis of pulp and paper mill sludge

Pyrolysis holds immense potential for clean treatment of pulp and paper mill sludge (PPMS), enabling efficient energy and chemical recovery. However, current understanding of PPMS pyrolysis kinetics and product characteristics remains incomplete. This study conducted detailed modeling of pyrolysis kinetics for two typical PPMSs from a wastepaper pulp and paper mill, namely, deinking sludge (PPMS-DS) and sewage sludge (PPMS-SS), and analyzed comprehensively pyrolysis products. The results show that apparent activation energy of PPMS-DS (169.25–226.82 kJ/mol) and PPMS-SS (189.29–411.21 kJ/mol) pyrolysis undergoes significant change, with numerous parallel reactions present. A distributed activation energy model with dual logistic distributions proves to be suitable for modeling thermal decomposition kinetics of both PPMS-DS and PPMS-SS, with coefficient of determination >0.999 and relative root mean square error <1.99 %. High temperature promotes decomposition of solid organic materials in PPMS, and maximum tar yield for both PPMS-DS (53.90 wt%, daf) and PPMS-SS (56.48 wt%, daf) is achieved at around 500 °C. Higher levels of styrene (24.45 % for PPMS-DS and 14.71 % for PPMS-SS) and ethylbenzene (8.61 % for PPMS-DS and 8.33 % for PPMS-SS) are detected in tar and could be used as chemicals. This work shows great potential to propel development of PPMS pyrolysis technology, enabling green and sustainable production in pulp and paper industry.

Study on lightening of coal tar with metal oxide supported γ-Al2O3 catalyst

In this experiment, a fixed bed of pyrolysis was used to conduct pyrolysis with coal and a mixture of coal and catalyst, and the distribution and composition of tar products were studied. The pyrolysis of raw coal was carried out at different temperatures and at different constant temperature times, and the effects of pyrolysis temperature and constant temperature pyrolysis time on tar product formation from raw coal pyrolysis were studied. γ-Al2O3 was used as the carrier, and 4 kinds of alkaline earth metal oxides (MgO, CaO, SrO, BaO), 3 kinds of subgroup metal oxides (Fe2O3, Co2O3, NiO) and 5 kinds of VIII metal oxides (Cr2O3, MnO2, CuO, ZnO, MnO2) were selected as active components. The supported γ-Al2O3 catalyst was prepared by the method of equal volume impregnation and roasting in a muffle furnace. The γ-Al2O3 catalyst was characterized by means of XPS, BET and SEM, and the mechanism of the mixed pyrolysis of coal with different metal oxide supported catalysts to generate tar was studied. The results showed that: (1) under the conditions of 450 °C, 500 °C, 550 °C and 600 °C, the maximum tar yield was 0.32 g at 600 °C, and the tar yield was higher at constant temperature for 15 min than at final temperature of 600 °C, with an increase of 15.63%. (2) Fe2O3/γ-Al2O3 catalyst resulted in the highest tar yield of 0.75 g, which was 134.38% higher than that of coal pyrolysis. (3) From the increase of light oil and phenol oil and the decrease of anthracene oil and asphalt, Co2O3/γ-Al2O3, Fe2O3/γ-Al2O3 and Cr2O3/γ-Al2O3 can improve the tar quality better.

Synergistic effect and chlorine migration behavior in co-pyrolysis of Pingshuo coal and polyvinyl chloride and directional chlorine enrichment using calcium oxide

Co-pyrolysis of waste plastics and low-rank coal is an important way to realize the recycling of plastic wastes and the clean and efficient conversion of coal. However, halogens released would cause equipment corrosion and affect tar quality when halogenated plastics were co-pyrolyzed with coal. For this reason, polyvinyl chloride (PVC), as a representative of halogenated plastic, was co-pyrolyzed with Pingshuo coal (PS) in a two-stage fixed-bed reactor. The synergistic effect between PS and PVC and the migration behavior of chlorine were investigated, and the in-situ removal of chlorine during pyrolysis was explored by adding a CaO bed in the second stage of the reactor. The results showed that the addition of PVC in PS has a positive synergistic effect on tar yield with a maximum tar yield increment of 2.30 wt% at 30 wt% PVC, which is related to the negative synergistic effect on gas yield. Furthermore, the addition of PVC increases the content of 1–3 ring aromatics and decreases the content of aliphatics in the tar. The chlorine content in char and tar increases significantly with the increase of PVC addition. The addition of a CaO bed can significantly reduce the yield of HCl and the chlorine content in the tar. At 700 ℃, the dehydrochlorination efficiency of CaO can reach 78.1%. However, the CO2 produced by PS pyrolysis will reduce the dehydrochlorination efficiency of CaO, and this effect of CO2 can be reduced by increasing the temperature of the CaO bed.

Insight into product characteristics from microwave co-pyrolysis of low-rank coal and corncob: Unraveling the effects of metal catalysts

Microwave pyrolysis of low-rank coal can provide high yield and quality of valuable products. Coupling with hydrogenated and catalytic pyrolysis is considered to achieve the selective or targeted generation of pyrolysis products. In this study, three metal catalysts KCl, Fe2O3, and CaO were used in the microwave catalytic co-pyrolysis of low-rank coal and corncob to investigate their effects on the temperature rise, product distribution, and product structure characteristics. The results showed that the maximum and final temperatures of microwave co-pyrolysis with the addition of a metal catalyst increased, and the corresponding yield and quality of tar were considerably improved. The porous structure of the char with the added metal catalyst was significantly enhanced, and the carbon microcrystal structure became significantly strong, but the change in thickness was minimal. The formation of aliphatic hydrocarbons and CO functional groups in both char and tar was inhibited when Fe2O3 and CaO were added. Among the three metal catalysts, CaO had the most obvious effect on the pyrolysis products, resulting in a maximum tar yield of 10.89 % and the highest light oil of 17.20 %. The char had a more regular and integrated porous structure; its Aar/Aal ratio reached a maximum of 12.603, showing the highest aromaticity. In addition, the total of valuable gas component and heat value of the pyrolysis gas arrived at 84.81 vol% and 14.93 MJ/m3, which showed excellent yield and performance. This work provides sufficient evidences for clean and efficient utilization of low-rank coal using catalytic microwave pyrolysis technology.

Slow pyrolysis experimental investigation of biomass tar formation and hydrogen production by tar reforming

The characteristics of pyrolysis tar and catalytic hydrogen production during tar reforming with catalysts were investigated. Through the pyrolysis experiment of wheat straw at 400–800 °C, the change of tar yield and tar composition with pyrolysis temperature was obtained. In order to remove tar, different nickel-based catalysts were prepared and catalytic experiments were carried out. The results showed that the pyrolysis tar yield first increased and then decreased with the increase of temperature, and the maximum tar yield was 32.82% at 700 °C. The generation of tar mainly comes from the thermal decomposition of biomass before 500 °C, the homogeneous reactions of tar compositions begin to occur after 500 °C. Through the characterization of the catalysts and their catalytic performance, it was found that due to the interaction of Ni and Ce on the support surface, Ni particles were more evenly distributed on the surface of the support. By adding Ce into Ni/HZSM-5, more oxygen vacancies are formed on the catalyst surface, which makes the catalyst have higher reducibility and more active sites. Compared with 9Ni/HZSM-5, 9Ni3Ce/HZSM-5 has a better catalytic performance with the tar conversion of 89.34% and H2 composition of 0.43.

CO2 based co-gasification of printed circuit board with high ash coal

Electronic wastes are accumulated in the environment due to their non-degradability nature, which makes them unsuitable for landfills. Printed circuit board (PCB) is one of the e-wastes significantly occupying the generated wastes. To utilize them efficiently, in the present study, PCB is thermally treated under N2 and CO2 conditions by pyrolysis and gasification processes at various temperatures. A maximum tar yield of 7.46% is obtained during PCB pyrolysis at 500 °C with a tar calorific value of 31.28 MJ/kg. CO2 gasification of PCB mixture at 1000 °C achieved the highest conversion of 97.6% resulting in a cold gas efficiency (CGE) of 91.9% and exergy efficiency of 82.9%. Further, high ash Indian coal is co-gasified with PCB mixture. It is found that the addition of PCB mixture, PCB resin, and PCB plastic in a 4:1 ratio (HAC: PCB) with HAC increased the CGE by 6.81%, 4.26%, and 2.3%, respectively. Further, the BET analyses of the co-gasification residue showed the generation of surface area as high as 186 m2/g and therefore, it can be suitable as a catalyst for cracking reactions. Further, the residue contains CaCO3, TiO2, and SnO2, which are potential additives in the concrete material for the construction of buildings.

Pengaruh Kondisi Temperatur Pirolisis Tandan Kosong Kelapa Sawit Terhadap Komposisi Produk Tar

Oil palm empty fruit bunch (EFB) is one of the biomass wastes that have a great potential of a bioenergy resource due to its natural properties, such as high calorific value. The conversion of EFB biomass into valuable biofuels can achieved through biochemical and thermochemical processes. Tar (bio-oil), the liquid product from the pyrolysis is one of the most attractive biofuels. The study aims to determine the effect of temperature process of pyrolysis EFB on its tar production under droptube reactor. The results showed that maximum tar yield was 43,80% obtained at 500 °C. The EFB tar produced at 500 °C was also determined to have a higher of phenol compound at 51,9%. The high phenolic content indicates its potential to be used for the production of renewable phenolic resins. Hence, the present work of pyrolysis of EFB presents itself as a promising method to produce phenol rich tar (bio-oil) from biomass waste.

Insight into synergistic effect of co-pyrolysis of low-rank coal and waste polyethylene with or without additives using rapid infrared heating

A newly infrared-heated reactor with a high heating rate (20 °C/s) was applied to explore the co-pyrolysis interactions between low-rank coal and waste polyethylene (PE), and further observe the effect of organic plastic additives (OPAs) in PE on co-pyrolysis interactions. PEs pyrolysis results revealed that white PE hose without additives (WPE) and black PE threading pipe with additives (BPE) exhibit significantly different product distribution. Co-pyrolysis results indicated that the addition of WPE in coal is conducive to forming tar, with a maximum tar yield increment of 6.23 wt% observed at coal/WPE (7:3). However, adding BPE in coal has a slight impact on the tar yield but significantly enhances the light fractions in tar, with a maximum light tar content increment of 6.00% at coal/BPE (9:1), revealing the interactions between OPAs volatiles and coal volatiles. The volatile-volatile interactions promote the cracking of waste PE to form short-chain aliphatic hydrocarbons and inhibit coal pyrolysis to generate aromatics and phenols. Furthermore, the chars from co-pyrolysis have a lower H/C ratio and higher C-centered radical concentration than coal char, further demonstrating that hydrogen has been transferred to the liquid products, which can provide an effective complement for understanding the co-pyrolysis interactions.

Biomass hydrogen donor assisted microwave pyrolysis of low-rank pulverized coal: Optimization, product upgrade and synergistic mechanism

Wheat straw (WS) has been used as a hydrogen donor to provide sufficient hydrogen for hydrogenated microwave pyrolysis of low-rank pulverized coal (PC). In this work, the effects of pyrolysis time, microwave power, the particle size of PC, and the ratio of PC to WS on microwave co-pyrolysis of PC and WS were investigated to optimize the experimental conditions. The pyrolysis products generated under the optimal conditions for the maximum tar yield were contrastively discussed, and the relevant synergistic mechanism was proposed. Results showed the temperature-rising rate of other conditions was positively correlated with the tar yield but not for the condition of the ratio of PC to WS. The tar yield reached the maximum value of 17.20% during microwave co-pyrolysis under the conditions of 0.68–1.00 mm of particle size of PC, 700 W of microwave power, 50% of WS, and 20 min of pyrolysis time. The microwave pyrolysis of PC was significantly improved when adding WS, resulting in increased yields of tar and pyrolysis gas by 13.21% and 12.40%, respectively, compared with PC alone. The aliphatic and aromatic hydrocarbons in the coal tar sharply decreased, but the phenols, alcohols, and others increased compared with those in the microwave pyrolysis of PC. There was a positive synergistic effect between PC and WS in microwave co-pyrolysis caused by volatiles and biochar generated from WS.

Evaluation of tar from the microwave co-pyrolysis of low-rank coal and corncob using orthogonal-test-based grey relational analysis (GRA)

Tar is a potential alternative to crude oil and can be produced through the pyrolysis technology of low-rank coal. However, the low H/C ratio of coal leads to unsatisfactory tar yield and quality. The use of corncob as a hydrogen donor to assist the microwave pyrolysis of low-rank coal through orthogonal-test-based grey relational analysis was investigated. The yield, structure, and component of tar under the optimum conditions were discussed. Results showed that pyrolysis time had the most obvious effect on tar yield, followed by corncob particle size, microwave power, and corncob additive amount, but the difference was small. The maximum tar yield of 8.85% was achieved under the following conditions: microwave power of 700 W, pyrolysis time of 30 min, corncob particle size of 0.420–0.841 mm, and corncob additive amount of 30%. The positive synergistic effect resulted in increased tar yield and decreased long-chain carbon structure and heteroatom organics in tar, thereby producing “lighter” and more “valuable” tar. This positive synergistic effect was due to the H free radicals and reactive oxygen-containing groups produced from corncob cracking.

The characteristics and mechanism for the formation of tars from low temperature pyrolysis of lignite

In this paper, the effect of pyrolysis conditions on low-temperature formation of tars characteristics and viscosity of lignite was investigated in a self-researched fixed bed reactor. The relationship between tar quality parameters and its formation and viscosity characteristics was investigated by multiple linear regression. The composition characteristics of low temperature tar were also investigated. The results showed that the yield and viscosity of tar increased with the increase of heating rate and pyrolysis temperature. Low temperature tar started to escape at 350 °C and reaches a maximum at 600 °C. The maximum tar yield was obtained at 550 °C–600 °C, 0.31%/min. The tar viscosity increased significantly after 550 °C, and the tar yield of isothermal pyrolysis was higher than that of non-isothermal pyrolysis after 500 °C. The tar yield under hydrogen atmosphere was higher than that under nitrogen, carbon dioxide, methane and carbon monoxide atmosphere. The tar yield increased gradually with the increasing of H2 flow rate, until it reached the maximum at the flow rate of 720 ml/min, which was 12.58%. The mathematical models of tar formation and viscosity characteristics of Yunnan lignite during low temperature pyrolysis were Yieldtar ( % )=12.14 H/C+48.35O/C−12.54fa+0.29Ad and Viscositytar( mPa⋅s )=14.99 H/C+62.53O/C−0.39fa, respectively. The content of aliphatic and aromatic components in tar increased with the increase of pyrolysis temperature, while the content of polar substances decreased gradually. The content of aliphatic and aromatic components was more than 53%, and the polar compounds content dropped to about 41.7% at 600 °C.

Estimating the levels of process parameters for tar and char production via fast pyrolysis of Hypericum perforatum and characterization of the products

The influence of pyrolysis temperature, pressure and heating rate was investigated on the tar and char yield from the fast pyrolysis of Hypericum perforatum (St. John's wort). The experiments were conducted using a fixed bed reactor. Response surface methodology (RSM), with a central composite design (CCD), was used for modeling and optimization of the process parameters. The optimum conditions were found to be at a temperature of 513.13 °C and 400 °C, pressure of 1 and 41 bar and heating rate of 489.39 °C/min and 150 °C/min for maximum tar and char yield, respectively. Maximum yields of tar and char were obtained as 32.98% and 41.23% under optimum process conditions, respectively. Scanning electron microscopy (SEM), ultimate analysis, and gas chromatography/mass spectrometry (GC/MS) were used to determine the physico-chemical properties of char, and the chemical properties of tar. The higher heating value of the chars produced at pressurized atmosphere were 29 MJ/kg. GC/MS analysis showed that the tar was rich in phenol, methyl and methoxy phenols, oxygenated benzenes and fatty acids. Furthermore, the formation of polycyclic aromatic hydrocarbons (PAHs) in the tar, obtained at pressurized pyrolysis in a nitrogen atmosphere, was investigated. Pressure increased the residence time of the volatile components in the reactor and this phenomenon led to the formation of PAHs. The derived tars were found to contain mainly 2-ring (naphthalene and its derivatives), 3-ring (acenaphthylene, Fluorene, Phenanthrene, 2-methyl anthracene), and 4-ring (Fluoranthene) PAHs.

Enhanced catalytic microwave pyrolysis of low-rank coal using Fe2O3@bluecoke absorber prepared by a simple mechanical ball milling

Fe2O3 and bluecoke (BC) powder are used in preparing novel and cheap carbon-based absorbers through simple mechanical ball milling and by enhancing catalytic microwave pyrolysis. The electromagnetic and catalytic properties of the active compositions and matrices are controlled, and the characteristics of the prepared Fe2O3@BC absorbers and pyrolysis products are detected and analyzed in detail through SEM–EDS, XRD, FT-IR, TG-DTG, and GC-MS. Results show that most of the Fe2O3 particles aggregate and uniformly form numerous flower clusters on the surfaces of the BC fragments, developing many edges and interface structures. The presence of iron oxides and iron in BC with Fe2O3 indicates that the catalysis of Fe2O3 on coal is caused by the iron mixture. Enhancement in microwave pyrolysis significantly and rapidly increases temperature and product distribution, and the maximum tar yield of 7.94 wt% is obtained with the Fe2O3@BC absorber. Product analysis shows that the “hot spot” effect of BC and Fe2O3 and the activation of Fe2O3 on free hydrogen result in the complete microwave pyrolysis of low-rank coal and thereby improve the yield and quality of tar and coal gas. Possibly caused by the introduction of magnetic loss and “rim–edge” effect, which enhances catalytic microwave pyrolysis, the synergistic effects of Fe2O3 and BC are confirmed by theoretical calculation and experiment results. The microwave pyrolysis technology of low-rank coal is feasible because of good economic and energy efficient microwave pyrolysis of low-rank coal, and fully utilized pyrolysis products and by-products.

Effects of Direct Coal Liquefaction Residue Additions on Low-Rank Pulverized Coal during Co-Pyrolysis

This study examined the co-pyrolysis characteristics of low-rank coal (SJC) and direct coal liquefaction residue (DCLR) through thermogravimetric analysis coupled with Fourier transform infrared spectrometry. It also investigated the influences of different mass fractions of DCLR to SJC on the co-pyrolysis characteristics and release regulation of gas phase components. Results showed that with increasing DCLR content, coke yield initially decreased and then increased, but tar and gas yield reversed. Different addition of DCLR changed the composition of the pyrolysis gas in various degrees, and reduced the content of-OH and nitrogen compounds in coke. The H2 content in the gas gradually increased. When 40% DCLR was added, the maximum tar yield was 22.79%, and the maximum H2 yield was 37.12%. At 60% DCLR, the lowest semi-coke yield was 65.01%, and the highest gas yield was 14.65%. The co-pyrolysis of SJC and DCLR can be divided into three stages. The first was the dry degassing stage, during which the adsorbed gas and small-molecule gas were removed on the coal surface at room temperature to 350 °C. The second stage (350 °C–650 °C) was the intense pyrolysis reaction stage, during which a large number of volatiles were obtained. The substantial weight loss rate peak appeared around 450 °C. The weight loss rate of pyrolysis gradually increased with increasing DCLR dosage. The co-pyrolysis of SJC and DCLR was not a simple sum between SJC and DCLR, which indicated a synergistic effect in the co-pyrolysis. The synergistic effect between SJC and DCLR enhances the interaction between free-radical fragments, thereby increasing the yield of pyrolysis tar. The third stage was the shrinkage of semi-coke from 650 °C to the end of the reaction. The polycondensation reaction between free-radical fragments to form solid coke with higher aromaticity, and H2 released.

Influence of temperature and Ca(OH)2 on releasing tar and coal gas during lignite coal pyrolysis and char gasification

Abstract The yield of tar and syngas has been investigated by catalytic pyrolysis of Pingzhuang lignite (PZL) over Ca(OH) 2 catalyst in temperature range of 600 °C-1000 °C in a tube furnace. The results show that the yield of volatile pyrolysis increases and char decreases with rising temperature for both raw and catalyzed Pingzhuang lignite. The hydrogen fraction (H 2 ) increased from 20% to 40% for the PZL sample; but, for the PZL-Ca(OH) 2 sample, H 2 fraction fluctuated randomly between 35 to 42%, with the maximum H 2 fraction found at 1000 °C. The Gas-chromatography mass-spectroscopic (GC-MS) analysis revealed that the maximum tar yield at 800 °C and 700 °C was obtained for PZL and PZL-Ca(OH) 2 , respectively. The surface morphology of PZL and PZL-Ca(OH) 2 chars underwent different transformation in the presence of catalyst as illustrated by SEM/EDX, FTIR, and BET analysis. Furthermore, char sample was investigated for the carbon conversion and reactivity index using TGA analysis under N 2 and CO atmosphere.

Environmental inhalants from tobacco burning: Tar and particulate emissions

Abstract Cigarette smoking is credited for decreasing the world population annually by about 1%. This paper therefore explores the carcinogenic and mutagenic residue (tar), and particulate matter from the thermal degradation of tobacco cigarettes coded, SPM and ES1, at a residence time of 2.0 s at 1 atm. This study was carried out in the temperature range 200–600 °C with nitrogen as the pyrolysis gas. Field emission gun scanning electron microscope was used to image the nature of particulate emissions from tobacco smoke. It was shown that tobacco smoke particulates are ultrafine; ∼22 and 28 nm for SPM and ES1 cigarettes respectively. Particle deposition fraction in the human lung and pulmonary lobes was simulated using the Multipath Particle Deposition (MPPD) model. The ultrafine particulates if inhaled are grave precursors for various respiratory health ailments. Maximum tar yield was produced at ∼400 °C. Thus, designing cigarettes that may be smoked at temperatures lower than 400 °C may be beneficial to the tobacco smoking community. From MPPD model runs, it was found that the pulmonary tissue retained the highest fraction (0.448) of particles of 22 nm geometric diameter in comparison to 0.418 fraction of the slightly larger particles of 28 nm geometric diameter from ES1 cigarette. This implies that the respiratory system has a poor clearance of particles of smaller geometric diameter. Thus, extremely ultrafine particulates are of grave concern to cigarette smokers.

Characterization of pyrolysis products from slow pyrolysis of live and dead vegetation native to the southern United States

Prescribed (i.e., controlled) burning is a common practice used in many vegetation types in the world to accomplish a wide range of land management objectives including wildfire risk reduction, wildlife habitat improvement, forest regeneration, and land clearing. To properly apply controlled fire and reduce unwanted fire behavior, an improved understanding of fundamental processes related to combustion of live and dead vegetation is needed. Since the combustion process starts with pyrolysis, there is a need for more data and better models of pyrolysis of live and dead fuels. In this study, slow pyrolysis experiments were carried out in a pyrolyzer apparatus under nitrogen atmosphere in two groups of experiments. In the first group, the effects of temperature (400–800 °C), a slow heating rate (5–30 °C min−1), and carrier gas flow rate (50–350 ml min−1) on yields of tar and light gas obtained from pyrolysis of dead longleaf pine litter were investigated to find the optimum condition which results in the maximum tar yield. The results showed that the highest tar yield was obtained at a temperature of 500 °C, heating rate of 30 °C min−1, and sweep gas flow rate of 100 ml min−1. In the second group of experiments, 14 plant species (live and dead) native to forests in the southern United States, were heated in the pyrolyzer apparatus at the optimum condition. A gas chromatograph equipped with a mass spectrometer (GC–MS) and a gas chromatograph equipped with a thermal conductivity detector (GC-TCD) were used to study the speciation of tar and light gases, respectively. The results showed that the tar composition is dominated by oxygenated aromatic compounds consisting mainly of phenols. The light gas analysis showed that CO and CO2 were the dominant light gas species for all plant samples on a dry wt% basis, followed by CH4 and H2.

Effects of various additives on the pyrolysis characteristics of municipal solid waste

Additives can have a significant impact on the pyrolysis process. The effects of three additives (CaO, MSW char and biomass) on the pyrolysis characteristics of municipal solid waste (MSW) were investigated using a fixed-bed reactor. In addition, the effects of additives and temperature on the MSW pyrolysis product yield, the composition of MSW pyrolysis gases, and the composition of MSW pyrolysis tar were investigated using fixed bed reactor, GC–MS and FTIR, respectively. The results showed that the maximum tar yield of the MSW reached 28.73% at 600 °C and the tar yield decreased with increasing amounts of CaO and MSW. The tar yield began to decrease when the additive amount of CaO was 5% and decreased to 23.05% when the additive amount of MSW char (C) was 30%. Synergistic pyrolysis of the biomass and MSW was observed when the additive amount of the pine increased to 75% (with a tar yield of 37.91%). Regarding gas composition, with increasing additives content, the CO2 yield decreased, while the CO yield increased. According to the FTIR analysis of the tar, CaO enhanced the condensation of the aromatic rings and converted the aliphatic hydrocarbons, while C reduced the oxygenic groups of the tar. The GC–MS results revealed that the additives decreased the yield of carboxylic acid and ethanol, and increased the ester yield. The additives were also found to have a deoxidation effect that decreased the acid content, potentially improving the quality and stability of the tar.

Scrap tyre pyrolysis: Modified chemical percolation devolatilization (M-CPD) to describe the influence of pyrolysis conditions on product yields

This paper attempts to develop a modified chemical percolation devolatilization (M-CPD) model that can include heat transfer, primary pyrolysis and the secondary cracking reactions of volatiles together to describe the pyrolysis of waste scrap tyre chip, as well as to examine the influence of operating conditions on the scrap tyre pyrolysis product yields. Such a study has yet to be conducted in the past, thereby leading to a large knowledge gap failing to understand the pyrolysis of the coarse feedstock appropriately. To validate the developed model, a number of operating parameters including reactor configurations, carrier gas compositions (argon and argon blended with CO2 and/or steam), scrap tyre chip size (0.5–15.0 mm), terminal pyrolysis temperature (400–800 °C) and heating rate (10 °C/min and 110 °C/min) were examined in a lab-scale fixed-bed pyrolyser, with a particular focus on the secondary cracking extents of the liquid tar. Through both experimental investigation and modelling approach, it was found that significant secondary cracking extent occurred upon the increase in the feedstock size, heating rate and residence time. Upon the fast pyrolysis, the average temperature gap between the centres of the coarse particle and reactor wall could reach a maximum of 115 °C for the tyre chips of 6–15 mm. Consequently, its primary volatiles underwent the secondary cracking reaction at an overall extent of 17% at a terminal temperature of 600 °C and a fast heating rate of 110 °C/min. Consequently, the yield of light gases including methane was increased remarkably. The flow rate of inert carrier gas was also influential in the secondary cracking, in which a maximum tar yield (54 wt%) was reached at a carrier gas flow rate of 1.5 L/min. This indicates the occurrence of secondary cracking has been largely minimised. At a pyrolysis temperature of 600 °C, the addition of CO2 in the carrier gas had an insignificant effect on the product yield distribution under the slow heating scheme. In contrast, the addition of steam resulted in a slight increase of carbon monoxide, presumably due to the occurrence of gasification reaction.

Study on the Inference Factors of Huangling Coking Coal Pyrolysis

In order to reasonably and efficiently utilize Huangling coking coal resource, coal particle, heating rate, holding time, pyrolysis temperature and others factors were dicussed for the influence of those factor on Huangling coking coal pyrolysis products. Several kinds of coal blending for coking experiments were carried out with different kinds of coal such as Huangling coking coal, Xida coal with high ash low sufur, Xinghuo fat coal with hign sulfur, Zhongxingyi coking coal with high sulfur, Hucun lean coal, mixed meager and lean coal. The results shown that the optimal coal particle size distribution was 0.5~1.5mm, the optimal heating rate was 8°C/min, the optimal holding time was 15min, the optimal pyrolysis temperature was 800°C for Huangling coking coal pyrolysis, the tar yield increased from 4.7% to 11.2%. The maximum tar yield of coal blending for coking under the best single factor experiment condition was 10.65% when the proportio of Huangling coking coal was 52%.