废旧高分子材料在回转窑内热解的研究：热解终温对热解产物的影响

以废旧高分子材料—ＰＥ塑料,ＰＶＣ塑料和废轮胎为试验物料,在外热式回转窑内进行了一系列热解试验。考察了热解终温对热解产物的产率及产物特性的影响。随热解终温的提高,热解气体的产率上升而半焦的产率下降;ＰＥ和ＰＶＣ的热解焦油的产率下降,而废轮胎则相反。在试验温度范围内热解气体的平均热值有一最大值;ＰＶＣ在热解过程中Ｃｌ－ＨＣｌ的转化率为５２０％～５６０％;热解终温对焦油的ＣＨ原子比、热值及族分均有一定影响;热解终温对热解半焦的热值、Ｃ和Ｈ残余率以及半焦反应活性也有一定的影响     

Effect of different temperatures on the properties of pyrolysis products of Parthenium hysterophorus

This research encompasses the use of noxious weed Parthenium hysterophorus as feedstock for pyrolysis carried out at varying temperatures of 300, 450 and 600°C. Temperature significantly affected the yield and properties of the pyrolysis products including char, syngas and bio-oil. Biochar yield decreased from 61% to 37% from 300 °C to 600 °C, whereas yield of gas and oil increased with increasing temperature. The pyrolysis products were physico-chemically characterized. In biochar, pH, conductivity, fixed carbon, ash content, bulk density and specific surface area of the biochar increased whereas cation exchange capacity, calorific value, volatile matter, hydrogen, nitrogen and oxygen content decreased with increasing temperature. Thermogravimetric analysis showed that the biochar prepared at higher temperature was more stable. Gas Chromatography-Mass Spectrometry analysis of biochar indicated the presence of alkanes, alkenes, nitriles, fatty acids, esters, amides and aromatic compounds. Number of compounds decreased with increasing temperature, but aromatic compounds increased with increasing temperature. Scanning electron micrographs of biochar prepared at different temperatures indicated micropore formation at lower temperature while increase in the size of pores and disorganization of vessels occurred at increasing temperature. The chemical composition was found to be richer at lower pyrolysis temperature. GC–MS analysis of the bio-oil indicated the presence of phenols, ketones, acids, alkanes, alkenes, nitrogenated compounds, heterocyclics and benzene derivatives.     

Catalytic pyrolysis of polypropylene to synthesize carbon nanotubes and hydrogen through a two-stage process

A two-stage reaction process was used to convert polypropylene (PP) into multi-walled carbon nanotubes (MWCNTs) and hydrogen-rich gas. The proposed process consisted of two stages: catalytic pyrolysis of PP over HZSM-5 zeolite in a screw kiln reactor and the subsequent catalytic decomposition of pyrolysis gases over a nickel catalysts in a moving-bed reactor for producing MWCNTs and hydrogen. The resultant gas mainly consisted of hydrogen and methane. SEM and TEM images revealed that carbon products in the moving-bed reactor were in the form of MWCNTs. XRD and TGA characterization indicated that high decomposition temperature resulted in the formation of more highly crystalline nanotubes. The influence of pyrolysis temperature (550-750 °C) and decomposition temperature (500-800 °C) on the performances of the two-stage reaction system were investigated. The MWCNT yield and hydrogen concentration increased with an increase in the decomposition temperature and reached a maximum at 700 °C. With increasing pyrolysis temperature the yield of pyrolysis gas increased while the liquid yield decreased. The yield of MWCNTs in the moving-bed reactor was determined by both the quantity and quality of the pyrolysis gas.     

Coal pyrolysis in a fluidized bed reactor simulating the process conditions of coal topping in CFB boiler

Simulating the conditions of pyrolytic topping in a fluidized bed reactor integrated into a CFB boiler, the study was devoted to the reaction fundamentals of coal pyrolysis in terms of the production characteristics of pyrolysis oil in fluidized bed reactors, including pyrolysis oil yield, required reaction time and the chemical species presented in the pyrolysis oil. The results demonstrated that the maximal pyrolysis oil yield occurred on conditions of 873 K, with a reaction time of 3 min and in a reaction atmosphere gas simulating the composition of pyrolysis gas. Adding H₂ and CO₂ into the reaction atmosphere decreased the pyrolysis oil yield, while the oil yield increased with increasing the CO and CH₄ contents in the atmosphere. TG-FTIR analysis was conducted to reveal the effects of reaction atmosphere on the chemical species present in the pyrolysis oil. The results clarified that the pyrolysis oil yield reached its maximum when the simulated pyrolysis gas was the reaction atmosphere, but there were slightly fewer volatile matters in the pyrolysis oil than the oil generated in the N₂ atmosphere. All of these results are expected not only to reveal the composition characteristics of the pyrolysis oil from different conditions of the coal topping process but also to optimize the pyrolysis conditions in terms of maximizing the light pyrolysis oil yield and quality.     

Study of the pyrolysis liquids obtained from different sewage sludge

Pyrolysis of sewage sludge in fluidized bed to produce bio-oil is under study as a useful way to valorise this waste. Sewage sludge is the waste produced in the wastewater treatment plants. Its composition may change due to the origin and to the non-standardized treatments in the wastewater treatment plants. The pyrolysis of three samples of anaerobically digested sewage sludge obtained from three different urban wastewater treatment plants was studied in this work. The organic and inorganic matter composition, and the volatile and ash content of these sewage sludge samples were different. The influence of these parameters on the pyrolysis product distribution and on some characteristics of these products was studied. It was determined that the ash content of the raw material had an enormous influence on the sewage sludge pyrolysis. An increase in the ash content of the sewage sludge caused an increase in the gas yield and a decrease in the liquid and the solid yield with the operational conditions studied. The increase of the volatile content of the sewage sludge samples caused an increase in the liquid yield. The H₂ proportion was the most influenced non-condensable gas. It increased significantly with the ash content. The viscosity of the pyrolysis oils decreased when the ash content augmented. On the other hand, the water content depended on the organic composition of the sewage sludge samples. The chemical composition of the pyrolysis oils was also affected by the sewage sludge ash content above all the proportion of polyaromatic hydrocarbons and nitrogen-containing aromatic compounds. These compound groups increased with the augment of the sewage sludge ash content. The oxygen-containing aliphatic compounds and the steroids decreased with the ash content, although its proportion in the sewage sludge liquid was also influenced by the organic matter composition of the sewage sludge samples.     

Effects of temperature and holding time during torrefaction on the pyrolysis behaviors of woody biomass

Torrefaction is the thermal treatment techniques performed at relatively low temperature (<300 °C) in an inert atmosphere, which aims to improve the fuel properties attractively. In this study, woody biomass (Leucaena leucocephala) was torrefied at various temperatures and holding times and the pyrolysis behaviors of the torrefied wood were examined in detail by using TG-MS technique. It was found that the carbon content and the calorific value of the torrefied leucaena increased significantly when temperature and holding time during the torrefaction increased. From the TG-MS analysis, the pyrolysis behaviors of the torrefied leucaena were significantly different from those of the raw leucaena. The char yield at 800 °C for the torrefied leucaena was increased when increasing the holding time during the torrefaction. On the other hand, the tar yield during the pyrolysis decreased significantly with the increase in the holding time during the torrefaction. Through the results from the TG-MS analysis, it was concluded that the structure of leucaena was changed by the torrefaction at temperature below 275 °C and the cross-linking reactions occurred during the pyrolysis resulting in increase in char yields and decrease in tar yields. It was also suggested that the longer the holding time during the torrefaction, the more the cross-linking reactions proceed during the pyrolysis. The results obtained from the study provide the basic information for the pyrolyser and/or gasifier design by using torrefied biomass as a fuel.     

含水量对神府煤快速热解过程气体释放及孔隙结构变化的影响

通过外添加水分改变神府煤含水量,利用高频加热炉进行快速热解,研究了含水量对神府煤快速热解过程的影响,考察了四种含水量神府煤快速热解气相产物分布及变化规律,利用孔/表面分析仪表征了固相产物的结构变化。结果表明,随着煤中含水量升高,热解气总体积和最大释放速率减小;热解焦的比表面积和孔容随含水量升高而增大,与原煤煤焦相比,含水煤制得热解焦中保留了较多小孔,孔隙结构更加发达;水分有利于抑制热解过程孔的阻塞与塌陷,提高煤焦表面的粗糙程度和多孔结构的复杂程度。     

用热重红外光谱联用技术研究混煤热解特性

用热重分析仪和傅里叶红外光谱仪，对混煤在惰性气氛中的慢速热解特性进行了动态分析，考察了煤种、掺混比例以及加热速率对热解的影响。结果表明，混煤的热解与单煤的热解有相似之处，热解组分的析出随温度的变化规律一致，但其组分析出量并不是单煤热解析出量的简单叠加。由于掺混煤种间的相互作用，混煤热解气体在析出时间和析出量上均发生了变化。通过对红外吸收光谱的分析，发现混煤热解气体析出规律受掺混煤种的影响很大，高活性煤种的存在会降低混煤热解的初析温度，增加热解气体的析出量，其掺混比例越高，影响也越明显。     

城市生活垃圾低温热解产气特性的实验研究

用直径200 mm的外热式固定床反应器,以城市生活垃圾中9种典型成分的混合物为实验物料,在300 ℃～700 ℃对其进行了低温热解的实验研究。结果表明,在其他条件相同的情况下,随着热解温度的提高,热解反应所需时间缩短;热解气的总产率、最大瞬时产率均增加;热解气的各成分随温度的升高呈现出不同的变化趋势;热解气的热值在600 ℃达到最大值,为15.13 MJ/m3,可满足民用燃气的要求。     

Influence of cation on the pyrolysis and oxidation of alginates

There is a growing interest in the production of chemicals and novel carbonaceous materials from marine biomass such as macroalgae (seaweed). The pyrolysis of macroalgae can produce a range of chemicals and chars with various properties. A large proportion of macroalgae is carbohydrate of which the alginates are dominant. The alginates are largely present bound with a cation, which can include calcium, sodium, magnesium or potassium. The thermal behavior of alginic acid, sodium alginate and calcium alginate have been investigated using batch pyrolysis experiments and thermal analysis including TGA-FTIR and Py-GC-MS to evaluate the influence of the cation. The change in cation from Na⁺ to Ca²⁺ significantly influences the pyrolysis behavior and in the case of Na alginate leads to significant swelling of the char, not observed for the Ca alginate or alginic acid. The Na alginate decomposes at a lower temperature than the Ca alginate and produces a different range of volatile components. The char from the Na alginate has been characterised by gas sorption for BET surface area analysis and there is evidence for mesoporosity. SEM analysis indicates significant differences in surface morphology for the Na alginate compared to Ca alginate. The cation appears to exert a significant influence on the pyrolysis and oxidative behavior of alginates. Py-GC-MS indicates that the cation also influences the devolatilisation products produced by pyrolysis. The volatile components from the Ca alginate resemble more closely the components from alginic acid whereas the volatile components from Na alginate include a range of cyclopentenone derivatives. It is proposed that the Na⁺ catalyses decomposition whereas the Ca²⁺ does not.     

裂解气相色谱-质谱联用技术研究黑香豆酊的热裂解行为

采用裂解气相色谱-质谱联用法研究了香精黑香豆酊在不同温度下的裂解行为,分析了黑香豆酊在不同温度下的热裂解产物,并用归一化法进行了定量。结果发现黑香豆酊在不同温度下表现出不同的转移行为,其热解产物和机理也各不相同。检索到苯并呋喃、香豆素和肉桂醛等16种致香物质。随着温度的升高,裂解产物中逐渐产生出有害物质。初步探讨了香豆素可能的裂解机理,为香味物质在卷烟燃烧过程的转化行为提供了例证。     

酸预处理对生物质热裂解规律影响的实验研究

在自制的热裂解机理实验台上进行了不同酸处理对稻壳以及白松的热裂解影响实验研究。经过盐酸浸泡后,稻壳中的金属离子含量明显降低;经盐酸洗涤后的稻壳热裂解焦油产量升高,由原始物料时的41.74%增加到7%盐酸洗涤后的52.88%,而气体和焦炭产量相应降低,并且随着盐酸浓度的增加,对应的趋势更加明显。酸洗涤后稻壳热裂解气体产物主要由CO和CO₂组成,其产量相比原样都有所降低;不同种类的酸对生物质热裂解规律的影响存在差异,盐酸因其去离子效果最好而对生物质热裂解产物分布影响最强;对白松原样以及酸洗后白松的微观结构进行了电镜分析,结果发现,硫酸对白松的微观结构产生了明显的影响。     

Evaluation of factors affecting pyrolysis in A microfurnace system

A styrene isoprene block copolymer, known as Kraton 1107, is used to study some of the parameters involved in the pyrolysis process. Using a continuous mode microfurnace pyrolysis system interfaced to a capillary gas chromatography system, the effect of pyrolysis temperature and gas flows through the pyrolysis chamber were studied. Comparisons in sample introduction methods were made. Introducing the sample in solution, rather than conventional solid sample introduction, was found to offer some advantages.     

Gasification and catalytic conversion of biomass by flash pyrolysis

The influence of the water content, the gasification atmosphere and the action of inorganic catalysts on biomass pyrolysis is discussed. The pyrolysis conditions are characterized by a heating rate of a wood sample of 250–300°C/s and a residence time of the gas in the hot zone of the reactor of less than 1 s. Volumes, carbon contents, weights and energy balances at different temperatures (600–1000°C) are tabulated. The total volume of pyrolysis gas and the yields increase with increasing temperature and water content. This increase is especially due to the production of hydrogen. A large part of the gasified hydrogen comes from water. Water that has not been driven off from green wood is more gasifiable than water that is re-added or from the atmosphere. Three types of catalysts were tested: alumina, aluminosilicate material and nickel-supported catalyst. The results show that it is possible to control the distribution of gas species by controlling the water content of the biomass and selecting the catalyst on which the wood is pyrolysed. A nickel catalyst on mordenite seems to be very efficient in directing pyrolysis gas production towards synthesis gas.     

Studies of grass forages and their fibrous fractions by pyrolysis gas chromatography – ion trap detection

Grass forage samples with different fiber content and composition, and their fibrous fractions, have been analyzed by pyrolysis – gas chromatography with ion trap detection. The identities of the pyrolysis fragments indicated their origin to be carbohydrates, lignin, and nitrogen compounds. Comparison of the resulting quantitative data by factorial variance revealed pyrogram peaks attributable to neutral detergent fiber, cellular contents, and lignin. Quantitative pyrolysis data from these components showed the same trends as those recorded by the method of Goering and Van Soest [1].     

热预处理影响褐煤热解行为研究

采用固定床反应器研究了不同气氛热预处理对内蒙胜利褐煤结构的改变,及其对后续热解行为的影响。结果表明,与原煤相比,热预处理后煤中羟基含量和芳香氢与脂肪氢的比减少,脂肪氢的相对含量增加。与未经处理的煤热解相比,N2、N2+O2、CO2气氛下热预处理后热解水收率下降,热解气收率增加,热解气中CO2含量增高,导致高位热值下降。过热水蒸气热预处理后,焦油质量收率提高3～4个百分点。热解焦油组成的变化与预处理气氛、温度密切相关,过热水蒸气200℃下预处理使得焦油中轻质组分的含量(沸点低于360℃的馏分)比原煤焦油提高了约27个百分点;水蒸气和模拟烟气混合气氛下在200℃及250℃预处理后,其热解焦油中轻油和酚油含量分别提高约60和42个百分点。     

Sulphur distribution in the products of waste tire pyrolysis

The aim of the presented work was to investigate the distribution of sulphur in tire pyrolysis products as well as the influence of process parameters (temperature and residence time) on sulphur distribution due to environmental concerns. Among modern methods used for waste tire recycling, pyrolysis is one of the most reasonable alternatives meeting current environmental standards. However, waste tire sulphur content can be a potential drawback for pyrolysis products utilisation as fuels. Sulphur is present in tires in different concentrations, depending on the type and age of the tires. Typical sulphur content in tires is about 1.6 mass %. In this paper, the distribution of sulphur in tire pyrolysis products was investigated. Tire pyrolysis yields three different products: liquid, gaseous, and solid residue composed mostly of carbon black (chars). Temperature and residence time are the two most important parameters affecting the yield and composition of the volatile fraction and they are therefore expected to affect the sulphur content in residues. Pyrolysis experiments were carried out in a laboratory pyrolysis reaction unit in the temperature range of 650°C to 750°C at different residence times: 88.6 s, 80.2 s, and 73.9 s. Liquid and solid products were analysed by elemental analysis and the distribution of total sulphur in tire pyrolysis products was calculated.     

Fluidised bed pyrolysis of Moroccan oil shales using the hamburg pyrolysis process

In the present work, the pyrolysis of the Moroccan Timahdit oil shale was studied, using a fluidised bed process. Four experiments were carried out at different temperatures between 520 and 630 °C. By mass balance could be shown that in relation to the kerogen content up to 60 wt.% of oil and 25 wt.% of gas are obtained. These are 40% higher yields compared with the Fischer assay. It was shown that the carbon in the residue, which is much lower (only 12 wt.%) than in the Fischer assay (26 wt.%), explains this difference.     

固体热载体热解霍林河褐煤实验研究

在处理量为10kg/h的粉煤-固体热载体移动床实验装置上,以循环灰为热载体对其进行了热解特性评价实验.考察了热解温度(460℃~610℃)、反应时间(6min~8min)及煤粒粒径对热解产物产率和组成的影响.结果表明,随着热解温度的升高,气体产率增大;焦油产率在520℃时达到最大值4.94%.热解煤气的热值为19.80...     

煤岩有机显微组分热解过程中HCN和NH3生成规律的研究

经等密度梯度离心分离，从褐煤、长焰煤、气煤和贫煤四种不同变质程度煤中获得了高纯度的有机显微组分。用石英管式反应器在600 ℃～900 ℃考察了煤岩有机显微组分热解过程中HCN和NH3的生成规律。实验结果表明，在显微组分热解过程中HCN主要是挥发分二次裂解的产物。在镜质组热解过程中，煤的变质程度越高，HCN的生成率越低，热解温度越高，HCN的生成率越高；同一种煤三种有机显微组分热解过程中，HCN的生成不仅与显微组分挥发分的质量分数有关，而且与显微组分中氮的存在形态有关，在较低温度热解时吡咯型氮质量分数高的煤样HCN的生成率较高。显微组分热解过程中NH3来自于挥发分的二次热裂解，与焦的热裂解有关，随煤变质程度增高，镜质组热解过程中NH3的收率降低；对同一种煤三种煤岩有机显微组分，由于其黏结性不同，含氮官能团和氢自由基的接触几率不同，生成NH3的能力也不同，惰质组的NH3生成率最高，壳质组最低；温度对NH3的生成也有影响，800 ℃NH3的生成率最高，惰质组NH3的生成率为11.8%，壳质组NH3的生成率为5.2%。