Co-pyrolysis characteristics of typical components of waste plastics in a falling film pyrolysis reactor

Waste plastics mainly come from MSW and usually exist in the form of mixed plastics. During the co-pyrolysis process of mixed plastics, various plastic components have different physicochemical properties and reaction mechanisms. Considering the high viscosity and low thermal conductivity of molten plastics, a falling film pyrolysis reactor was selected to explore the rapid co-pyrolysis process of typical plastic components(PP, PE and PS).The oil and gas yields and the compositions of pyrolysis products of the three components under different ratios at pyrolysis temperatures were analyzed to explore the co-pyrolysis characteristics of PP, PE, and PS. The study is of great significance to the recycling of waste plastics.

Co-pyrolysis characteristics and interaction route between low-rank coals and Shenhua coal direct liquefaction residue

To reasonably utilize the coal direct liquefaction residue(DLR), contrasting research on the co-pyrolysis between different low-rank coals and DLR was investigated using a TGA coupled with an FT-IR spectrophotometer and a fixed-bed reactor. GC–MS, FTIR, and XRD were used to explore the reaction mechanisms of the various co-pyrolysis processes. Based on the TGA results, it was confirmed that the tetrahydrofuran insoluble fraction of DLR helped to catalyze the conversion reaction of lignite. Also, the addition of DLR improved the yield of tar in the fixed-bed, with altering the composition of the tar. Moreover, a kinetic analysis during the co-pyrolysis was conducted using a distributed activation energy model. The co-pyrolysis reactions showed an approximate double-Gaussian distribution.

Experimental study on co-pyrolysis characteristics of typical medical waste compositions

Thermal decomposition of 21 kinds of binary mixtures between typical medical compositions was investigated under nitrogen conditions by dynamic thermogravimetric analysis(TGA) at 25–800 °C. The weighed sum method(WSM) coupled with thermal analysis was applied to study the interaction between components. Then, co-pyrolysis kinetic model of the binary mixtures(tube for transfusion(TFT) and gauze) was established to verify the reliability of conclusions. The results show the follows. 1) Strong or weak interactions are shown between binary mixtures containing polyvinyl chloride(PVC), the main ingredient of TFT. The addition of other medical waste could enhance first stage decomposition of TFT. While, the secondary stage pyrolysis may be suppressed or enhanced or not affected by the addition. 2) There exists no interaction between catheter and other component, the DTG peak temperature representing Ca CO3 decomposition in catheter fraction is obviously lower than that of pure catheter; while,the shape of DTG peak keeps unchanged. 3) No evident reaction occurs between the other mix-samples, it is considered that their co-pyrolysis characteristics are linear superposition of mono-component pyrolysis characteristics.

Co-pyrolysis of Sewage Sludge with Paint Sludge: Kinetics and Thermodynamic Analysis via Iso-conversional Methods

This study explored the synergistic interaction of sewage sludge(SS)and automotive paint sludge(PS)during co-pyrolysis for the optimized treatment of sewage sludge in cement kiln systems,utilizing thermogravimetric analysis(TGA)and thermogravimetric-mass spectrometry(TGA-MS).The result reveals the coexisting synergistic and antagonistic effects in the co-pyrolysis of SS/PS.The synergistic effect arises from hydrogen free radicals in SS and catalytic components in PS,while the main source of the antagonistic effect is that,during the mechanical mixing process,the SS/PS is converted from the particulate form into a dough-like rubbery which contributes to the film-forming effect,hindering the volatilization of volatile components.SS/PS co-pyrolysis reduces the yielding of tar production while increasing coke and gas.This study will provide some in-depth insights into the co-pyrolysis of SS/PS,and offer theoretical support for the subsequent research on the collaborative disposal processes in cement kilns.

Thermogravimetric analysis and kinetic modeling of the co-pyrolysis of a bituminous coal and poplar wood

The co-pyrolysis of coal and biomass has proven to be a promising route to produce liquid and gaseous fuels as well as specific value-added chemicals while contributing to mitigating CO_(2) emissions.The interactions between the co-processed feedstocks,however,need to be elucidated to support the development of such a thermochemical conversion process.In this context,the present work covers the kinetic analysis of the co-pyrolysis of a bituminous coal with poplar wood.In this research,biomass was blended with coal at two different mass ratios(10%(mass)and 20%(mass)).Thermogravimetric analyses were carried out with pure and blended samples at four heating rates(5,10,15 and 30℃·min^(-1)).A direct comparison of experimental and theoretical results(based on a simple additivity rule)failed to yield a clear-cut conclusion regarding the existence of synergistic effects.Kinetic analyses have therefore been achieved using two model-free methods(the Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose models)to estimate the rate constant parameters related to the pyrolysis process.A significant decrease of the activation energy has thus been observed when adding wood to coal(activation energies associated with the blend containing 20%(mass)of biomass being even lower than those estimated for pure wood at low conversion degrees).This trend was attributed to the possible presence of synergies whose related mechanisms are discussed.The rate constant parameters derived by means of the two tested models were finally used to simulate the evolution of the conversion degree of each sample as a function of the temperature,thus leading to a satisfying agreement between measured and simulated data.

A theoretical insight about co-pyrolysis reaction of natural gas and coal

The co-pyrolysis of natural gas and coal is a promising way for the production of acetylene due to its high efficiency for energy and hydrogen utilization.This work investigated the thermodynamics for the copyrolysis reaction of natural gas and coal using density functional theory.The favorable reaction conditions are presented in the form of phase diagrams.The calculation results show that the extra amount of methane may benefit the production of acetylene in the co-pyrolysis reaction,and the C/H ratio of 1:1,temperature around 3000 K and pressure at 0.1 MPa are most favorable.The results would provide basic data for related industrial process for the production of acetylene.

Co-Pyrolysis Characteristics and Kinetic Analysis of Oil Sludge with Different Additives

The addition of effective additives can effectively improve the pyrolysis performance of oil sludge(OS)and have a great potential to reduce pyrolysis costs.In the present study,co-pyrolysis performance of OS with different proportions of additives at a heating rate of 10°C/min was conducted in a thermal analyzer.Walnut shell,Fe_(2)O_(3),K_(2)CO_(3),PVC and the pyrolysis char produced from OS at the final pyrolysis temperature of 700℃were selected as the additives.TG results showed that the OS pyrolysis with and without additives can be divided into five reaction stages,which include volatilization of free water,the escape of light components,the cleavage of heavy components,carbon decomposition and inorganic minerals decomposition.The addition of additives decreased the maximum weight loss rate when the blending ratio was 5 wt%during OS pyrolysis.Kinetic analysis revealed that the overall activation energy of pyrolysis reaction was lower during pyrolysis of OS with the addition of walnut shells and pyrolysis char.The activation energy of three main reaction stages all decreased during co-pyrolysis of OS with K_(2)CO_(3)and PVC.

Thermogravimetric characteristics of corn straw and bituminous coal copyrolysis based the ilmenite oxygen carriers

Herein,the co-pyrolysis reaction characteristics of corn straw(CS)and bituminous coal in the presence of ilmenite oxygen carriers(OCs)are investigated via thermogravimetry coupled with mass spectrometry.The results reveal that the participation of OCs weakens the devolatilization intensity of co-pyrolysis.When the CS blending ratio is<50%,the mixed fuel exhibits positive synergistic effects.The fitting results according to the Coats-Redfern integral method show that the solid-solid interaction between OCs and coke changes the reaction kinetics,enhancing the co-pyrolysis reactivity at the high-temperature zone(750-950C).The synergistic effect is most prominent at a 30%CS blending ratio,with copyrolysis activation energy in the range of 26.35-40.57 kJ·mol^(-1).

Importance of oxygen-containing functionalities and pore structures of biochar in catalyzing pyrolysis of homologous poplar

Biochar and bio-oil are produced simultaneously in one pyrolysis process,and they inevitably contact and may interact,influencing the composition of bio-oil and modifying the structure of biochar.In this sense,biochar is an inherent catalyst for pyrolysis.In this study,in order to investigate the influence of functionalities and pore structures of biochar on its capability for catalyzing the conversion of homologous volatiles in bio-oil,three char catalysts(600C,800C,and 800AC)produced via pyrolysis of poplar wood at 600 or 800℃or activated at 800℃,were used for catalyzing pyrolysis of homologous poplar wood at 600℃,respectively.The results indicated that the 600C catalyst was more active than 800C and 800AC for catalyzing cracking of volatiles to form more gas(yield increase by 40.2%)and aromatization of volatiles to form more light or heavy phenolics,due to its abundant oxygen-containing functionalities acting as active sites.The developed pores of the 800AC showed no such catalytic effect but could trap some volatiles and allow their further conversion via sufficient aromatization.Nevertheless,the interaction with the volatiles consumed oxygen on 600C(decrease by 50%),enhancing the aromatic degree and increasing thermal stability.The dominance of deposition of carbonaceous material of a very aromatic nature over 800C and 800AC resulted in net weight gain and blocked micropores but formed additional macropores.The in situ diffuse reflectance infrared Fourier transform spectroscopy characterization of the catalytic pyrolysis indicated superior activity of 600C for removal of -OH,while conversion of the intermediates bearing C=O was enhanced over all the char catalysts.

Ignition processes and characteristics of charring conductive polymers with a cavity geometry in precombustion chamber for applications in micro/nano satellite hybrid rocket motors

The arc ignition system based on charring polymers has advantages of simple structure,low ignition power consumption and multiple ignitions,which bringing it broadly application prospect in hybrid propulsion system of micro/nano satellite.However,charring polymers alone need a relatively high input voltage to achieve pyrolysis and ignition,which increases the burden and cost of the power system of micro/nano satellite in practical application.Adding conductive substance into charring polymers can effectively decrease the conducting voltage which can realize low voltage and low power consumption repeated ignition of arc ignition system.In this paper,a charring conductive polymer ignition grain with a cavity geometry in precombustion chamber,which is composed of PLA and multiwall carbon nanotubes(MWCNT)was proposed.The detailed ignition processes were analyzed and two different ignition mechanisms in the cavity of charring conductive polymers were revealed.The ignition characteristics of charring conductive polymers were also investigated at different input voltages,ignition grain structures,ignition locations and injection schemes in a visual ignition combustor.The results demonstrated that the ignition delay and external energy required for ignition were inversely correlated with the voltages applied to ignition grain.Moreover,the incremental depth of cavity shortened the ignition delay and external energy required for ignition while accelerated the propagation of flame.As the depth of cavity increased from 2 to 6 mm(at 50 V),the time of flame propagating out of ignition grain changed from 235.6 to 108 ms,and values of mean ignition delay time and mean external energy required for ignition decreased from 462.8 to 320 ms and 16.2 to 10.75 J,respectively.The rear side of the cavity was the ideal ignition position which had a shorter ignition delay and a faster flame propagation speed in comparison to other ignition positions.Compared to direct injection scheme,swirling injection provided a more favorable flow field environment in the cavity,which was beneficial to ignition and initial flame propagation,but the ignition position needed to be away from the outlet of swirling injector.At last,the repeated ignition characteristic of charring conductive polymers was also investigated.The ignition delay time and external energy required for ignition decreased with repeated ignition times but the variation was decreasing gradually.

基于代价敏感Char-CNN的Web威胁识别方案

随着互联网技术的迅速发展,网络安全面临的威胁越发严峻,Web攻击量连年翻倍增长.针对当前Web威胁识别方法手动提取特征识别准确率低、正常和恶意类别样本分布不均衡的问题,本文提出了基于代价敏感的字符级卷积神经网络(Character-level Convolutional Neural Networks,Char-CNN)的Web威胁识别方案.首先分析Web请求特征,将原始数据统一格式,读取数据并拼接成字符序列,根据预先指定的索引字典将字符序列进行编码;其次利用字符级别CNN提取请求信息,对字符编码进行特征提取和特征选择用于模型训练;最后嵌入代价敏感学习,修改神经网络模型交叉熵损失函数,增加恶意样本分类错误的代价,通过反向传播调整模型参数及权值,进而利用Softmax层进行威胁识别.实验表明,基于代价敏感的字符级卷积神经网络进行Web威胁识别方案的准确率达到98.99%,相比已有威胁识别方案,在精确率、召回率和F1分数均有提升,并验证了本方案在不平衡数据集上的有效性.

Energetic,bio-oil,biochar,and ash performances of co-pyrolysis-gasification of textile dyeing sludge and Chinese medicine residues in response to K_(2)CO_(3),atmosphere type,blend ratio,and temperature

Hazardous waste stream needs to be managed so as not to exceed stock-and rate-limited properties of its recipient ecosystems.The co-pyrolysis of Chinese medicine residue(CMR)and textile dyeing sludge(TDS)and its bio-oil,biochar,and ash quality and quantity were characterized as a function of the immersion of K_(2)CO_(3),atmosphere type,blend ratio,and temperature.Compared to the mono-pyrolysis of TDS,its co-pyrolysis performance with CMR(the comprehensive performance index(CPI))significantly improved by 33.9%in the N_(2)atmosphere and 33.2%in the CO_(2)atmosphere.The impregnation catalyzed the co-pyrolysis at 370℃,reduced its activation energy by 77.3 kJ/mol in the N_(2)atmosphere and 134.6 kJ/mol in the CO_(2)atmosphere,and enriched the degree of coke gasification by 44.25%in the CO_(2)atmosphere.The impregnation increased the decomposition rate of the co-pyrolysis by weakening the bond energy of fatty side chains and bridge bonds,its catalytic and secondary products,and its bio-oil yield by 66.19%.Its bio-oils mainly contained olefins,aromatic structural substances,and alcohols.The immersion of K_(2)CO_(3)improved the aromaticity of the copyrolytic biochars and reduced the contact between K and Si which made it convenient for Mg to react with SiO_(2)to form magnesium-silicate.The co-pyrolytic biochar surfaces mainly included-OH,-CH_(2),C=C,and Si-O-Si.The main phases in the co-pyrolytic ash included Ca_(5)(PO_(4))_(3)(OH),Al_(2)O_(3),and magnesium-silicate.

Co-pyrolysis of bituminous coal and biomass in a pressured fluidized bed

An experimental study on co-pyrolysis of bituminous coal and biomass was performed in a pressured fluidized bed reactor.The blend ratio of biomass in the mixture was varied between 0 and 100 wt%,and the temperature was over a range of 550–650℃ under 1.0 MPa pressure with different atmospheres.On the basis of the individual pyrolysis behavior of bituminous coal and biomass,the influences of the biomass blending ratio,temperature,pressure and atmosphere on the product distribution were investigated.The results indicated that there existed a synergetic effect in the co-pyrolysis of bituminous coal and biomass in this pressured fluidized bed reactor,especially when the condition of bituminous coal and biomass blend ratio of 70:30(w/w),600℃,and 0.3 MPa was applied.The addition of biomass influenced the tar and char yields and gas and tar composition during co-pyrolysis.The tar yields were higher than the calculated values from individual pyrolysis of each fuel,and consequently the char yields were lower.The experimental results showed that the composition of the gaseous products was not in accordance with those of their individual fuel.The improvement of composition in tar also indicated synergistic effect in the co-pyrolysis.

Improving hydrocarbons production via catalytic co-pyrolysis of torrefied-biomass with plastics and dual catalytic pyrolysis

To increase the low yield and selectivity of aromatic hydrocarbons during the biomass pyrolysis process,we torrefied the biomass and then co-pyrolyzing with plastics such as high-density polyethylene(HDPE),polystyrene(PS),ethylene-vinyl acetate(EVA)and polypropylene(PP)and also single and dual catalyst layouts were investigated by Py-GC/MS.The results showed that non-catalytic fast pyrolysis(CFP)of raw bagasse(RBG)generated no aromatics.After torrefaction non-CFP of torrefied bagasse(TBG)generated low aromatic yield.Indicating that torrefaction would enhance the proportion of aromatics during the pyrolysis process.The CFP of TBG_(200℃)and TBG_(240℃)over ZSM-5 produced the total aromatic yield of 1.96 and 1.88 times higher,respectively,compared to non-CFP of TBG.Furthermore,the addition of plastic could increase H/Ceff ratio of the mixture,consequently,increase the yield of aromatic compounds.Among the various torrefied-bagasse/plastic mixtures,the CFP of TBG/EVA(7:3 ratio)mixture generated the highest the total aromatic yield of 7.7 times more than the CFP of TBG alone.The dual catalyst layout could enhance the yield of aromatics hydrocarbons.The dual-catalytic co-pyrolysis of TBG_(200℃)/plastic(1:1)ratio over USY(ultra-stable Y zeolite)/ZSM-5,improved the total aromatics yield by 4.33 times more than the catalytic pyrolysis of TBG_(200℃)alone over ZSM-5 catalyst.The above results showed that the yield and selectivities of light aromatic hydrocarbons can be improved via catalytic co-pyrolysis and dual catalytic co-pyrolysis of torrefied-biomass with plastics.

Pyrolysis and co-pyrolysis of lignite and plastic

The study firstly discusses the pyrolysis characteristics and kinetics by thermogravimetric analysis （TGA）, and then investigates the pyrolysis of lignite and co-pyrolysis with plastic （polyethylene or polypropyl- ene） in tube furnace. Meanwhile, the research focuses on the co-pyrolysis products under different mix- ing ratios as well as pyrolysis products at different testing temperatures and heating rates. The results show that higher final testing temperature and lower heating rate contribute to bond fission in lignite pyrolysis, resulting in less char product. In co-pyrolysis, lignite acts as hydrogen donor, and the yields of char and water rise with increasing amount of plastic in the mixture, while the yields of gas and tar decrease; and a little admixture of plastic will promote the production of gas and tar. Kinetic studies indi- cate that in temperature range of 530-600℃, activation energies of lignite are higher than those of lig- nite/plastic blends, and as plastic mass ratio increases from 0% to 10%, samples need less energy to be decomposed during co-pyrolysis.

Thermogravimetric and Synergy Analysis of the Co-Pyrolysis of Coconut Husk and Laminated Plastic Packaging for Biofuel Production

Unlike plastic,biomass can also be converted and produce high quality of biofuel.Co-pyrolysis of coconut husk(CH)and laminated plastic packaging(LPP)were done in this study.Synergy between these two feedstock was calculated by using thermogravimetric(TGA)and derivative thermogravimetry(DTG)analysis.Different activation energies of the reactions in the co-pyrolysis of CH and LPP were evaluated using the Coats-Redfern method.Results showed an activation energy ranging from 8 to 37 kJ/mol in the different percentage composition of the co-pyrolysis.Also,thermal degradation happens in two-stages in the copyrolysis of CH and LPP,in which CH degrades at the temperature range of 210℃ to 390℃ while LPP degrades in temperatures 400℃-600℃.Co-pyrolysis of CH and LPP can be an alternative for biofuel production and can also reduce the waste problems in the community.

Regulating the Localization of Intumescent Flame Retardant for Improving the Flame Retardancy of Ethylene-vinyl Acetate Copolymer Using Polyamide 6 as a Charring Agent

Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.

A Novel Siamese Network for Few/Zero-Shot Handwritten Character Recognition Tasks

Deep metric learning is one of the recommended methods for the challenge of supporting few/zero-shot learning by deep networks.It depends on building a Siamese architecture of two homogeneous Convolutional Neural Networks(CNNs)for learning a distance function that can map input data from the input space to the feature space.Instead of determining the class of each sample,the Siamese architecture deals with the existence of a few training samples by deciding if the samples share the same class identity or not.The traditional structure for the Siamese architecture was built by forming two CNNs from scratch with randomly initialized weights and trained by binary cross-entropy loss.Building two CNNs from scratch is a trial and error and time-consuming phase.In addition,training with binary crossentropy loss sometimes leads to poor margins.In this paper,a novel Siamese network is proposed and applied to few/zero-shot Handwritten Character Recognition(HCR)tasks.The novelties of the proposed network are in.1)Utilizing transfer learning and using the pre-trained AlexNet as a feature extractor in the Siamese architecture.Fine-tuning a pre-trained network is typically faster and easier than building from scratch.2)Training the Siamese architecture with contrastive loss instead of the binary cross-entropy.Contrastive loss helps the network to learn a nonlinear mapping function that enables it to map the extracted features in the vector space with an optimal way.The proposed network is evaluated on the challenging Chars74K datasets by conducting two experiments.One is for testing the proposed network in few-shot learning while the other is for testing it in zero-shot learning.The recognition accuracy of the proposed network reaches to 85.6%and 82%in few-and zero-shot learning respectively.In addition,a comparison between the performance of the proposed Siamese network and the traditional Siamese CNNs is conducted.The comparison results show that the proposed network achieves higher recognition results in less time.The proposed network reduces the training time from days to hours in both experiments.

继发性噬血细胞综合征病因、临床特点及预后分析

目的:了解继发性噬血细胞综合征(HLH)的病因、临床特征及预后,以提高对HLH的认识,减少临床HLH的误诊和漏诊率。方法:收集2015年1月至2021年12月经本院收治的75例成人继发性HLH患者的病历资料,对其病因、临床特点、实验室检查结果、治疗及预后等进行回顾性分析。随访至末次出院时间。结果:75例患者中,感染相关HLH最常见(45.33%),其次为淋巴瘤相关HLH(17.33%)。临床表现以发热最为常见(97.67%),实验室指标中NK细胞活性(98.31%降低)、sCD25浓度(93.22%升高)、血清铁蛋白(94.44%升高)在诊断中灵敏度更高。将不同病因HLH患者初诊时临床表现及实验室指标进行比较,性别、淋巴结肿大、骨髓形态是否可见噬血现象对原发病的诊断更有价值(均P<0.05)。将不同病因HLH患者的治疗方案与临床转归进行比较,自身免疫性疾病相关HLH采用激素+环孢素治疗临床缓解率最高(83.3%)(P<0.05)。患者总体12个月的生存率为26.7%,其中感染相关HLH患者12个月的生存率最低(14.7%),自身免疫性疾病相关HLH患者12个月的生存率最高(63.6%)。结论:成人继发性HLH病因和临床特点多样,预后凶险,病情严重程度具有异质性,早期明确病因对HLH预后具有重要意义,需要进一步提高对HLH的认识。

准东煤分步和直接化学链燃烧特性

化学链燃烧作为高效的低碳排放燃烧技术,在提高燃料利用率和减少CO_(2)排放方面显示出其独特优势。采用Fe_(2)O_(3)/Al_(2)O_(3)载氧体,利用两段式固定床反应器开展了准东煤直接和分步化学链燃烧试验,探究了载氧体反应前后理化特性。发现准东煤热解挥发分化学链燃烧碳转化率和CO_(2)选择性随温度和载氧体与煤质量比(OC/C)增加而升高。OC/C和温度升高提高半焦化学链燃烧碳转化率,但降低CO_(2)选择性。相比煤直接化学链燃烧,在相同条件,分步化学链燃烧CO_(2)选择性大幅提高、碳转化率有所降低。反应温度800℃,分步化学链燃烧CO_(2)选择性达89.51%,相比直接化学链燃烧提升了29.18%。反应温度950℃,分步化学链燃烧碳转化率在60.40%,比直接化学链燃烧降低6.78%。与半焦反应后载氧体还原程度高于与煤热解挥发分反应后载氧体,半焦与载氧体的反应是煤化学链燃烧的限制因素之一。本研究为实现准东煤低碳清洁燃烧提供重要理论依据和技术支撑。