Continuous high-temperature fluidized bed pyrolysis of coal in complex atmospheres: Product distribution and pyrolysis gas

This study is devoted to investigating the continuous coal pyrolysis in a laboratory fluidized bed reactor that fed coal and discharged char continuously at temperatures of 750–980 °C and in N₂-base atmospheres containing O₂, H₂, CO, CH₄ and CO₂ at varied contents. The results showed that the designed continuous pyrolysis test provided a clear understanding of the coal pyrolysis behavior in various complex atmospheres free of and with O₂. The effect of adding H₂, CO, CH₄ or CO₂ into the atmosphere on the tar yield was related to the O₂ content in the atmosphere. Without O₂ in the atmosphere, adding H₂ and CO₂ decreased the pyrolysis tar yield, but the tar yield was conversely higher with raising the CO and CH₄ contents in the atmosphere. In O₂-containing atmospheres, the influence from varying the atmospheric gas composition on the product distribution and pyrolysis gas composition was closely related to the oxidation or gasification reactions occurring to char, tar and the tested gas.     

Gas Evolution from the Pyrolysis of Jordan Oil Shale in A Fixed-bed Reactor

Jordan oil shale from El-Lajjun deposit was pyrolysed in a fixed-bed pyrolysis reactor and the influence of the pyrolysis temperature between 400 to 620°C and the influence of the pyrolysis atmosphere using nitrogen and nitrogen/steam on the product yield and gas composition were investigated. The gases analysed were H₂, CO, CO₂ and hydrocarbons from C₁ to C₄. The results showed for both nitrogen and nitrogen/steam that increase the pyrolysis bed temperature from 400 to 520°C resulted in a significant increase in the oil yield, after which temperature the oil yield decreased. The alkene/alkane ratio including ethene/ethane, propene/propane, and butene/butane ratios, can be used as an indication of pyrolysis temperature and the magnitude of cracking reactions. Increasing alkene/alkane ratio occurring with increasing pyrolysis temperature. The alkene/alkane ratio for nitrogen/steam pyrolysis atmosphere was lower than the one found under nitrogen atmosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

微型流化床反应分析仪中原位/非原位煤焦气化动力学研究

利用新开发的微型流化床反应分析仪(micro-fluidized bed reaction analysis, MFBRA) 考察了义马烟煤半焦的原位以及两种非原位半焦气化行为并测定了其动力学参数,其中,原位半焦气化是指煤热解温度和气氛与半焦气化过程一致,非原位半焦1气化是指煤在Ar气氛下热解,热态条件下直接在CO₂气氛下气化;非原位半焦2气化是指煤在Ar气氛下热解,冷却收集后再在CO₂气氛下气化。研究发现,原位半焦具有最大的比表面积和最小的平均孔径,石墨化程度最弱,且对CO₂的化学吸附能力最强,表面活性位点最多。在最小化气体扩散的实验条件下,原位半焦气化反应的反应速率明显比非原位半焦气化反应快,且求取的活化能数据较小。实验揭示了原位半焦和非原位半焦结构和反应性的差异,也证明了MFBRA对原位等温气化反应的适用性。     

不同常压流化床煤气化方案的模型预测 Ⅰ. 模型建立及验证

为评价不同气化方案对常压流化床气化的影响，从化学动力学角度并结合化学平衡建立了流化床气化模型，该模型考虑了煤热解和气化所经历的各反应过程。模型预测结果与文献报道的试验数据吻合较好，气化组分的平方误差和在10%左右，表明该模型可以用来预测各种气化方案对常压流化床气化的气化过程、生成煤气组分和气化效率等方面的影响。     

Thermal self-sustainability of biochar production by pyrolysis

The pyrolysis of several agricultural and biofuel production residues (grape residues, sugarcane residues, dried distiller's grain, palm oil residues, apple pomace and forestry residue) has been carried out in a pilot bubbling fluidized bed pyrolyzer operating under a range of temperature from 300 to 600 °C and two vapor residence times (2 and 5 s), with the aim of determining their pyrolysis behavior including products yields and heat balance. The composition of the product gases was determined, from which their heating value was calculated. The liquid bio-oil was recovered with cyclonic condensers. The thermal sustainability of the pyrolysis process was estimated by considering the energy contribution of the product gases and of the liquid bio-oil in relation to the pyrolysis heat requirements. The most promising biomass feedstocks for the sustainable production of biochar were indentified. Furthermore, this study presented the char yield in relation to the excess heat that could be obtained by combusting the gas and bio-oil coproducts of biochar production, as functions of pyrolysis temperature and vapor residence time.     

Influences of Temperature and Coal Particle Size on the Flash Pyrolysis of Coal in a Fast-entrained Bed

IntroductionCoal is the major primary energy source in China,which accounts for about three quarters of the total en-ergy consumption.Most of coal in China contains a rel-atively high content of volatile substances.The reserveof lignite accounts for about…     

H2气氛下褐煤快速热解过程中CH4逸出规律的分析

在带有输送煤样的管式反应器上进行了霍林河褐煤加压快速氢解实验,分析了H₂对煤/半焦的化学键断裂和对CH₄生成规律的影响。在加压快速氢解条件下,CH₄产率随着热解温度升高、压力的增大而增大;在50% H₂气氛下,操作压力为1.0 MPa、温度为900 ℃时,CH₄产率为8.08%,达到最大,较N₂气氛下的提高了72.5%。H₂或H·自由基诱发了芳环的开裂、侧链、脂肪链和醚键的断裂,促进了煤热解。CH₄产率的增加主要是由于外部供H的结果;热解温度低于700 ℃时,H₂对煤结构中活性基团的作用促进了煤热解,导致了CH₄产率的增加;而热解温度高于700 ℃后,煤/半焦加氢气化促进了CH₄产率的增加。     

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。     

吡啶萃取对烟煤热解过程焦油生成特性的影响

煤中含有以非共价键结合的可萃取物，煤的萃取物和萃余物热解反应性不同。本研究首先用醋酸消除煤中静电作用力，再以吡啶萃取消除氢键作用力，通过热重和固定床研究了煤萃取物和萃余物的热解特性。相对于原煤，萃取物（E1）的H/C原子比较高，而萃余物（R1）比原煤的孔径有所增大。热重实验表明，萃取物热分解温度低，失重率大；萃余物在485℃之前失重大于原煤，温度高于485℃小于原煤。固定床氮气热解表明，萃取物（E1）的焦油产率和气体比原煤高；萃余物（R1）的焦油产率低于原煤焦油产率。而氢气气氛下，萃取残渣的焦油产率明显高于原煤，这是由于吡啶萃余物具有更开放的孔结构，有利于加氢热解过程氢向孔内扩散，减少了缩聚反应。     

加拿大合成原油瓦斯油裂解反应规律与产物生成机理

利用小型固定流化床实验装置研究了加拿大合成原油重瓦斯油(HGO)和轻瓦斯油(LGO)的催化裂解性能和热裂解性能。HGO和LGO催化裂解总低碳烯烃(乙烯+丙烯+丁烯)产率在660℃附近达到最大值,分别为33.8%和35.6%。HGO和LGO热裂解反应程度很大,700℃的转化率分别为66.7%和76.3%。HGO热裂解总低碳烯烃的产率在680℃达到最大值27.9%。通过对比分析催化裂解与热裂解气体产物产率的比值发现,催化剂的加入促进了乙烯和液化气的生成,同时抑制了甲烷和乙烷的生成。研究结果揭示了小分子烃类的生成机理,甲烷和乙烷主要是自由基反应的产物,乙烯和液化气是自由基反应和正碳离子反应的共同产物。     

Production of fungicidal oil and activated carbon from pistachio shell

The main objective of this study was to evaluate the feasibility of pistachio shell as a biomass feedstock for the production of fungicidal oil and a precursor for the production of activated carbon by physical activation. For this purpose, pistachio shell was pyrolyzed in a fixed bed reactor at the different temperatures (300-600 °C). The pyrolysis products were identified as gas, bio-oil, aqueous solution and char. The product distribution from pyrolysis process did not significantly change when the pyrolysis temperature was above 300 °C. The pyrolysis gas product had low calorific value since it contained the high proportion of carbon oxides. Because of their high oxygen content, the bio-oils were found not to be used as a fuel. Thus, the bio-oil was tested again four different types of fungi (pathogenetic, wood decaying and saprophyting). It was shown fungicidal activity again all tested fungi at the concentration of 10-50 mg ml⁻¹. The pyrolysis char was evaluated as a precursor for the production of activated carbon. The surface area and micropore volume of the activated carbon produced from the char by CO₂ activation at 900 °C were found to be 708 m² g⁻¹ and 0.280 cm³ g⁻¹, respectively.     

Catalytical and thermal pyrolysis of polyolefins

Polyolefins have a high potential for alternative oil production since they contain only carbon and hydrogen atoms. By pyrolysis of these materials up to 95% can be obtained as oil and gas. Upgrading the products by catalytic cracking of polyolefins is a subject of growing interest in the last years as less energy is needed for the pyrolysis and more valuable products are formed. Numerous studies have been reported in which a variety of catalysts such as zeolites, silica-alumina, mesoporous MCM-41, solid acids and reaction conditions have been investigated. In our studies we used Lewis acids and mixtures of Ziegler–Natta catalyst such as TiCl₄, AlCl₃ to pyrolyse polypropylene. Experiments were carried out in a batch reactor as well as in a fluidized bed process. The pyrolysis temperature can be decreased by 100 °C compared to runs without catalysts. A drastic increase in the amount of low boiling compounds (C4 hydrocarbons) can be observed by the use of the catalysts instead of longer chained hydrocarbons.     

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.     

油页岩固定床热解反应器中内构件强化作用

在内构件(传热板和中心集气管)外热式固定床反应器中研究了油页岩热解产物生成特性,并与无内构件的相同常规固定床反应器内的油页岩热解行为对比,考察了两反应器中油页岩升温特性、热解产物分布、页岩油品质以及气体产物组成的变化规律.结果表明,内置传热板和中心集气管显著强化了反应器内的传热,相对于无内构件常规固定床反应器,料层升温速率提高了约2倍.对于依兰油页岩,其热解页岩油产率明显提高,最高达11.1 wt%(干燥基),明显高于无构件常规固定床反应器获得的页岩油产率.随着外加热炉温度的升高,内构件固定床反应器的页岩油产率逐渐增加,而无内构件常规固定床反应器的页岩油产率则明显降低.当外加热炉温度为1000℃时,前者页岩油产率是后者的2.3倍,并且内构件固定床反应器的热解水产率较低.两反应器中热解气产物组成相近,其H2与CH4之和占气体总量的70 vol%左右,热值为4406~5400 kcal/Nm3.     

Bio-oil production by flash pyrolysis of sugarcane residues and post treatments of the aqueous phase

The pyrolysis of three sugarcane residues (internal bagasse, external and whole plant) has been carried out in a pilot bubbling fluidized bed pyrolyzer operating under a range of temperature from 300 °C to 600 °C and two vapor residence time (2 and 5 s), with the aim of determining their pyrolysis behavior including products yields and heat balance. The composition of the product gases was determined, from which their heating value was calculated. The liquid bio-oil was recovered with cyclonic condensers and separated into two phases, an aqueous phase and an organic phase. The energy content of the organic phase was determined in comparison with common fossil fuels. Activated carbon adsorption and distillation at 110 °C were used to treat the aqueous phase, with the aim of recovering valuable hydrocarbons and purifying the aqueous phase for wastewater disposal. Furthermore, the thermal sustainability of the pyrolysis process was estimated by considering the energy contribution of the product gases and of the liquid bio-oil in relation to the pyrolysis heat requirements. The optimum pyrolysis temperatures were identified in terms of maximizing the liquid yield, maximizing the energy from the product bio-oil, and maximizing the net energy from the product bio-oil after ensuring a self-sustainable process by utilizing the product gases and part of bio-oil as heat sources.     

煤焦油在超临界水中的改质研究

在自制的间歇式高压反应釜中，对煤焦油在超临界水中的改质反应进行了研究。考察了温度、反应停留时间、水密度等对产物分布及组成的影响。通过与N2气氛下的焦油常压热解、高压热解过程所得结果进行对比，表明煤焦油在超临界水中发生了轻质化反应，获得一定量的轻质化油品；超临界水介质的存在还对产气量和过程结焦产生一定的抑制作用。为获得较高的轻组分收率，最佳的反应条件为：450℃左右，反应停留时间约为20 min，水密度约为0.40 g/cm3在此反应条件下的轻质油收率为51.55 w%，比原料中的增加了约30％。     

煤-焦炉气共热解特性的研究Ⅰ.固定床热解反应特性

在１０ｇ固定床反应器中对先锋褐煤在焦炉气气氛下的热解特性及有关工艺参数，如反应压力、升温速率等的影响进行了详细考察，并与其同等条件下的加氢热解特性进行了对比分析。实验结果表明，在反应压力５ＭＰａ、升温速率５Ｋ／ｍｉｎ，终态温度９２３Ｋ条件下，先锋褐煤在焦炉气气氛下的热解转化率为５９．０％（ｄａｆ），焦油收率达３５．８％（ｄａｆ）。与同等条件下的纯氢气氛（３ＭＰａ）相比，转化率降低了约７％（ｄａｆ），而焦油收率提高了约７％（ｄａｆ）。这说明焦炉气中的诸如甲烷等其它组分的存在对煤的热解行为有重要作用。由于煤加氢热解受传质影响，因此不同工艺参数对热解反应影响很大，较高压力下的慢速升温有利于提高转化率和油品收率；升温速率对油品收率影响较为明显，慢速升温有利于提高油品收率。     

循环流化床内废轮胎的热解油化

介绍了以循环流化床反应器为主体的废轮胎热解油化装置,实验过程,实验结果及分析。通过评价热解条件对气体成分及油、碳和气产物产率的影响,以及热解油品的成分分析,得出如下结论：（１）较高的温度和较好的停贸时间会生成过多的不凝气（主要成分为ＣＨ４、Ｈ２,Ｃ２ＨＶ和ＣＯ等）,降低油的产率,过低的温度和加热速率导致严重的碳化,同样会降低油产率。（２）热解油品的组成成分非常复杂,芳烃占了很大比例,其次是烷烃和非     

炉前煤低温干馏工艺中脱硫行为的模拟研究

为了提供燃煤炉前低温干馏系统中硫的脱除和转化的工业设计依据，采用自制的程序升温固定床反应器，在模拟燃煤炉前低温干馏的工况下考察了热解温度及Ca/S原子比对热解产物中硫分布的影响。结果表明，由于CaO的存在，循环流化床（CFB）锅炉的循环灰具有明显的固硫作用，在480℃~640℃、煤热解气、液产物中60％～70％的硫以CaS的形式固定在灰中。相同热解温度下，固硫作用随着Ca/S原子比的提高而增加，焦油收率和焦油中硫含量均有所下降。     

Recycling of carbon fibre reinforced polymeric waste for the production of activated carbon fibres

Composite waste composed of carbon fibres and polybenzoxazines resin has been pyrolysed in a fixed bed reactor at temperatures of 350, 400, 450, 500 and 700 °C. Solid residues of between 70 and 83.6 wt%, liquid yields 14 and 24.6 wt% and gas yields 0.7 and 3.8 wt% were obtained depending on pyrolysis temperature. The derived pyrolysis liquids contained aniline in high concentration together with oxygenated and nitrogenated aromatic compounds. The pyrolysis gases consisted mainly of CO₂, CO, CH₄, H₂ and other hydrocarbons. The carbon fibres used in the composite waste were separated from the char of the solid residue via oxidation of the char at two different temperatures and investigated for their mechanical strength properties. The carbon fibres recovered from the sample pyrolysed at 500 °C and oxidised at 500 °C exhibited mechanical properties which were 90% of that of the original virgin carbon fibres. Steam activation of the recovered carbon fibres was carried out at 850 °C at different times of activation. The effect of activation time on BET surface area, activated carbon fibres yield, porosity and the morphological structure of activated carbon fibres was evaluated. A maximum BET surface area of over 800 m² g⁻¹ was obtained for the activated carbon fibres produced at 850 °C for 5 h of activation. Nitrogen adsorption-desorption isotherms showed that the adsorption capacity increased as the activation time increased up to 5 h of activation and then after that decreased.