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…     

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.     

CFD Simulation of a Hydrogen／Argon Plasma Jet Reactor for Coal Pyrolysis

A Computational Fluid Dynamics (CFD) model was formulated for DC arc hydrogen/argon plasma jet re-actors used in the process of the thermal H2/Ar plasma pyrolysis of coal to acetylene. In this model, fluid flow, convective heat transfer and conjugate heat conductivity are considered simultaneously. The error caused by estimating the inner-wall temperature of a reactor is avoided. The thermodynamic and transport properties of the hydrogen/argon mixture plasma system, which are usually expressed by a set of discrete da-ta, are fitted into expressions that can be easily implemented in the program. The effects of the turbulence are modeled by two standard k-ε equations. The temperature field and velocity field in the plasma jet reactor were calculated by employing SIMPLEST algorithm. The knowledge and insight obtained are useful for the design improvement and scale-up of plasma reactors.     

Analysis of Geting Bituminous Coal by Electrospray Ionization and Direct Analysis in Real Time Mass Spectrometry

Understanding the structure and composition of coals is important for effective, clean, and value-added utilization. In addition to gas chromatography/mass spectrometry which is commonly used to analyze coal, mass spectrometry (MS) may be used with other ion sources such as electrospray ionization (ESI) and direct analysis in real time (DART) for characterization. In this work, Geting bituminous coal was extracted sequentially and exhaustively with petroleum ether, carbon disulfide, methanol, acetone, an isometric acetone/carbon disulfide mixture, tetrahydrofuran, and an isometric tetrahydrofuran/carbon disulfide mixture. Raw coal, extracts, and the extraction residue were analyzed using MS equipped with ESI or DART. Organic heteroatomic species in the extracts were determined by liquid chromatography-mass spectrometry equipped with ESI. Molecular weight distributions of organic species in raw coal, extracts, and extraction residue were characterized by ESI-MS and DART-MS. Associated molecules and homologous compounds in coal extracts were identified.     

在线裂解气相色谱-质谱法研究单琥珀酸薄荷酯的裂解行为

采用在线裂解气相色谱-质谱联用技术对单琥珀酸薄荷酯的裂解行为进行了研究。在氦气氛围中,分别在300、400、500、600、700、800和900℃下对单琥珀酸薄荷酯进行热裂解,并通过毛细管气相色谱-质谱对裂解产物进行了定性和半定量分析。共鉴定出薄荷醇、p-薄荷-3-烯和琥珀酸等75种裂解产物。结果表明,单琥珀酸薄荷酯在700℃以下裂解出薄荷醇、p-薄荷-3-烯和3-甲基-6-异丙基环己烯等具有致香和清凉作用的物质;而700℃以上没有释放出致香物质。随着裂解温度的升高,裂解产物越来越复杂,有害物质如苯、甲苯、蒽和荧蒽等的含量也逐渐增加。此方法可直接进样,重现性好(相对标准偏差≤2.01%)。根据裂解产物的种类及相对含量变化规律,探讨了裂解成分的形成机理。     

非磁性纳米SiO_2颗粒在磁场流化床中的流态化

研究了非磁性纳米SiO2颗粒在添加磁性大颗粒磁场流化床中的流化性能。磁性大颗粒的添加量在20%～60%(wt)之间,磁感应强度的大小分别为0.0477、0.0596、0.0715 T。实验中通过测定床层膨胀曲线、床层压降曲线,详细地考察了磁性大颗粒的添加量、磁感应强度及气速的大小对纳米SiO2颗粒流化性能的影响。结果表明:把磁场能引入普通流化床中之后,加入的磁性粗颗粒能够有效地破碎纳米SiO2床层中的活塞、沟流和大聚团,降低最小流化速度,且在最小流化速度时无气泡,使床层膨胀比增加,提高床层的整体流化质量;在流化颗粒相中,磁场能的加入还可以保持床层的稳定性,维持流态化所需的气体体积。     

柱层析-高效液相色谱测定煤沥青中16种多环芳烃

建立了高效液相色谱测定煤沥青甲苯抽提液中16种美国环境保护署(EPA)重点监控多环芳烃(PAHs)含量的方法。以Agilent PAHs色谱柱为分离柱,不同比例混合的乙腈和水作流动相进行梯度洗脱,紫外检测器检测,16种PAHs的线性范围为0.5~20 mg/L,相对标准偏差小于2%,加标回收率为83.7%~98.9%。对两种不同来源的煤沥青进行分析,结果显示,两种煤沥青中16种PAHs的含量分别为107.89 g/kg和103.04 g/kg,其中苯并[a]芘含量分别为11.86 g/kg和13.85 g/kg。该方法可用于不同种煤沥青中致癌性PAHs的准确测定。     

毛细管气相色谱/傅立叶变换红外光谱分析高温煤焦油中的重油馏分

在原有工作基础上 ,采用毛细管气相色谱 /傅立叶变换红外光谱 -色谱保留指数 ( GC/ FTIR- RI)联合解析技术 ,研究了高温煤焦油重油馏分的化学组成。分别从重油馏分 F7( 30 0～ 330℃ )和 F8( 330～ 360℃ )中分离并鉴定出 70和 61种化合物 ,了解到不同配煤工艺对煤焦油组成与性能的影响 ,从而获得了一些有意义的结果 ,为煤焦油的集中加工和新产品开发提供了重要依据     

低煤级煤热解H2生成动力学及其与第一次煤化作用跃变的关系

用开放体系的热重-质谱联用仪(TG/MS)研究了7种低煤级煤的热解特征、H2的生成动力学特征以及它们与第一次煤化作用跃变的关系. 结果显示, 煤热解失重率在碳含量(Cdaf)为80%(质量分数)和镜质组最大反射率(R0max)为0.60%附近发生转折; 氢气生成的特征温度参数以及动力学参数均在Cdaf为80%(R0max为0.60%)左右表现为最低; 氢气的总产率在此处最大. 这些特征参数的极值点刚好与第一次煤化作用跃变点一致, 说明这些参数可以反映第一次煤化作用跃变的发生. 结合傅立叶变换红外(FTIR)光谱法获得的煤结构特征, 对影响机制进行了分析解释, 认为是由以下3个方面的原因导致的: (1)煤中脂肪类含氧官能团的演化特征; (2)可溶有机质的低温热缩聚作用; (3)有机质的“两极分化”作用.     

流化床CVD淀积过程中铝膜微结构及表面形貌的研究

考察了在常压流化床CVD反应器中利用三异丁基铝的热分解反应在高折射率玻璃微珠表面淀积铝膜时,淀积温度和时间对铝膜微结构和表面形貌的影响.SEM谱的表面形貌分析表明,提高淀积温度时,铝膜经过三维岛状→孔洞结构→连续致密膜的变化;延长淀积时间,铝膜的晶粒会变粗变大.AES谱的表面化学组成分析表明,在较高的淀积温度下铝膜中碳的残留并不明显,但发生了玻璃微珠基材中Ti,Ba等元素向铝膜中的扩散.Ti的扩散有利于形成连续致密的铝膜.     

光散射技术在蛋白质晶体生长研究中的应用和进展

光散射技术广泛应用于生物大分子的晶体生长研究中,它包括静态光散射和动态光散射两种。利用静态光散射可以测定蛋白质溶液渗透的第二维里系数;利用动态光散射可以测定蛋白质溶液的平动扩散系数,获得溶液中蛋白质粒子的流体力学半径及分布情况,分离蛋白质结晶的成核与生长过程,研究大分子的聚集行为和晶体生长的动力学。借助光散射技术可以实现蛋白质晶体生长过程的动态控制。近些年光散射仪器向着小型化、轻便化的方向发展,光散射技术不断得到改进,日益完善,不仅用于地面实验,也应用于空间领域蛋白质晶体生长的研究中。     

Evolution of products during the degradation of polyethylene in a batch reactor

The thermal degradation of two polyethylene samples (LDPE and HDPE) has been carried out in a batch reactor under dynamic conditions. The evolution of products generated after regular intervals of 5 min (temperature increments of approximately 25 °C) has been analyzed. The behaviour of LDPE and HDPE has been compared, and no differences in the quantity and weight fraction of the gaseous products obtained have been found. For both polymers, n-paraffins are the major products at the very beginning of the process, while as the decomposition proceeds 1-olefins are more abundant. The condensed fraction is much larger than the gaseous fraction and its analysis reveals some differences between the behaviour of LDPE and HDPE at the beginning of the degradation process. These differences disappear at higher temperatures where more similar trends are observed. 1-Olefins, n-paraffins, dienes and olefins with wide carbon number distributions are the most important condensed compounds obtained in the thermal degradation of both polyethylenes. The formation of 1-olefins and n-paraffins begins at slightly lower temperatures than for dienes and olefins. On the other hand, as the temperature increases, the amount of low and high molecular weight compounds increases at the expense of intermediate molecular weight products and the former become the most important by the end of the degradation process. This behaviour could be related to the thermal cracking of waxes through secondary reactions.     

Pyrolysis of solid waste in a rotary kiln: influence of final pyrolysis temperature on the pyrolysis products

Temperature is one of the most important parameters in pyrolysis reaction. In present work, an externally heated laboratory-scale rotary-kiln pyrolyser was designed and developed. The influence of final pyrolysis temperature (FPT) on the pyrolytic products of solid wastes has been studied. Raising FPT caused increasing gas yield and decreasing semi-coke yield. The average heat value of the gas also changed with FPT. The content of aliphatic hydrocarbons in PE tar increased initially and then decreased with increasing FPT. Parallel to this, the content of aromatic ring changed conversely. FPT had obvious influence on the primary and elemental analysis data of the semi-cokes. The CO₂ reactivity of the semi-cokes also varied with the FPT. The kinetic parameters of the semi-cokes were different for the same material at the different FPT.     

密度泛函理论研究温度和取代基对4-亚芳基亚氨基-1,2,4-三唑-3(2H)-酮气相热分解的影响

采用密度泛函理论(DFT)方法, 在B3LYP/6-31＋＋G(d,p)水平上研究了4-亚芳基亚氨基-1,2,4-三唑-3(2H)-酮及其类似物的气相热分解反应. 从热力学性质、几何结构参数、自然电荷分布、温度效应等角度探讨不同取代基对标题物热分解反应的影响. 结果表明: R (R＝H, CH2CH2CN)取代基对反应影响很小; 而苯环上Y (Y＝MeO, Me, H, Cl和NO2)取代基对活化自由能(ΔG≠)、键长(ΔR≠)、键角(Δα≠)和自然电荷(Δq≠)变化的影响与Hammet常数(σ)呈现线性关系ΔP≠＝ρσ＋C (P＝G, R, α和q, r＞0.95). 给电子基团使得相应的活化自由能降低, 键长变短, 键角变大, 自然电荷增加; 吸电子反之.     

CFB煤燃烧/热解双反应器中热解室对立管内气固流动特性的影响

考察了循环流化床煤燃烧/热解双反应器系统中热解室的存在对立管内的压力分布及气固流动状况的影响。提升管的内径100 mm、高6 m，立管的内径44 mm、高3 m，热解室的截面积200 mm×200 mm、高770 mm。结果表明，随着提升管内表观气速Ur的增加，有无热解室立管内均为负压差流动，负压差梯度随着Ur的增加而减小。有热解室时，热解室内要保持一定的料位高度，整个立管内固体颗粒的流动为负压差移动床流动；没有热解室时，立管内为稀相流动和移动床流动同时存在，立管内平衡料柱高度随Ur的增加而升高。随着循环量Gs的增加，两种类型的立管内负压差梯度均随之增大，也存在着流动形态的差别。循环量Gs的增加会引起立管内平衡料柱高度的降低。立管内气固相对滑移速度也随着循环量Gs的增加而增大。     

Ni-Co-LaNi5复合电极材料在碱性介质中的电催化析氢性能

电催化析氢反应是电能向化学能转化的一个有效途径,是电化学科学中一个非常值得深入研究的课题。阴极析氢超电势的降低,是提高析氢活性,降低电解能耗的关键。为了提高电极的电催化活性,一是可通过提高电极表面的真实表面积,来降低电解过程中电极表面的真实电流密度,达到降低析氢超电势的目的;另一发展方向是提高电极材料本身的电化学活性,即寻找高催化活性的新型析氢材料犤1犦。由于过渡金属具有特殊的d电于结构,是目前公认的电化学活性最好的电极材料,而在过渡金属中,Ni及Ni合金将是研究的主要方向,其中多元合金复合材料将成为该技术发展…     

Effect of Starvation and Shock Loads on the Biodegradation of 4-Chlorophenol in a Discontinuous Moving Bed Biofilm Reactor

The influence of starvation (defined as the period without substrate) and shock loads on the performance of a moving bed sequencing batch reactor degrading 4-chlorophenol (4CP) were investigated. The biomass was acclimated to biodegrade 100 mg/L of 4CP, and the colonization of the packing material was followed. Two starvation periods and two shock loads were studied. The degradation capacity of the suspended and the attached biomass present on the moving bed was also evaluated. The experiments showed that, after the starvation period, the specific degradation rate decreased from 30.5 to 28.5 and 20 mg 4CP/gVSS/h, when starvation periods of 24 and 48 h were applied, respectively. When two concentration peaks of 500 and 1,050 mg/L were applied, a loss of 6% and 8% on the specific degradation rate, respectively, was also observed. The moving bed thus showed great robustness against starvation periods and shock loads. Suspended biomass presented higher specific degradation rates, but attached biomass did not generate a metabolite that is inhibitory when it accumulates.     

The potential of MXene materials as a component in the catalyst layer for the Oxygen Evolution Reaction

MXenes are a class of 2D/layered materials which are highly conductive, hydrophilic, have a large electrochemical surface area and are easily processible into electrodes for energy applications. Since the discovery of MXenes over ten years ago, these materials have been mainly used in the preparation of electrodes for batteries and supercapacitors. However, due to their aforementioned properties, MXenes could potentially be utilised as a component in the catalyst layer for the Oxygen Evolution Reaction (OER). This opinion piece will discuss some of the recent literature in the area of hybrid catalysts consisting of various Transition Metal Oxides (TMOs) and MXenes for the OER. We will also discuss current drawbacks and future outlook in this new area of research.     

A Study of Carbon Deposition on Catalysts During the Catalytic Partial Oxidation of Methane to Syngas in a Fluidized bed

The deposition of carbon on catalysts during the partial oxidation of methane to syngas has been investigated in a fluidized bed. It was found that the relative rate of carbon deposition follows the order Ni>>Pd>Pt, Rh. Although the rate of carbon deposition in the fluidized bed was much lower than that in the fixed bed, carbon deposition could still be detected in the fluidized bed if a CH₄ /O₂ ratio in greater than 2.3 was used.