升温速率对油页岩热解特性的影响

采用热分析方法,在非等温条件下对茂名和桦甸的油页岩进行了热解试验研究。研究了从常温到900℃之间不同升温速率(10,20,40,50,100℃/m in)对油页岩热分解反应的影响以及油页岩的H/C,O/C,Cdaf,Vdaf等因素与(dw/dt)m ax之间的关系。根据试验数据建立了热解动力学模型,利用积分法求得表观活化能和频率因子等动力学参数。试验结果表明,油页岩热解可分为3个阶段,其中第2阶段(200—600℃)是热解反应最激烈的区域,挥发份几乎全部析出。而第3阶段是碳酸盐热解阶段,茂名油页岩由于碳酸盐含量低,此阶段变化甚微。     

Influence of heating rate on the pyrolysis of oil shale

The decomposition of oil shale from the Kvarntorp deposit in Sweden has been investigated using isothermal and non-isothermal methods. It was found that the heating rate during the initial non-isothermal period in the isothermal experiments had a considerable effect on the rate of devolatilization. At heating rates in the order of 10⁵°C/s the total weight loss exceeded the weight loss predicted from the volatile matter according to a proximate analysis.The effect of particle and sample size on the rate of decomposition (weight loss) was studied and found to have a significant influence at heating rates of the order of 10⁵°C/s while no effect was detected at heating rates around 200 °C/s (isothermal) or below 50°C/min (non-isothermal). The decomposition at low heating rates was completed at temperatures below 600°C and about 50 percent of the devolatilization could be described by first order kinetics with an apparent activation energy of 130 KJ/mole.At heating rates of 200°C/s (isothermal) the decomposition could also be described by simple first order kinetics but with an activation energy of 67 KJ/mole, thus indicating a different rate-determining mechanism.     

Effect of demineralization and heating rate on the pyrolysis kinetics of Jordanian oil shales

The effect of mineral matter content on the activation energy of oil shale pyrolysis has been studied. Kerogen was isolated from raw oil shale by sequential HCl and HCl/HF digestion. Oil shale and kerogen samples were pyrolyzed in a Thermogravimetric Analyzer at different heating rates (1, 3, 5, 10, 30, and 50 °C/min) up to a temperature of 1000 °C. Total mass loss of all oil shale samples remained almost constant irrespective of the heating rate employed, whereas it decreased with the increase of heating rate for kerogen (74.5 to 71.4%). From the pyrolysis profile activation energy (Ea) was found to vary between 70 and 83 kJ/mol for oil shale, while 82-112 kJ/mol has been determined for isolated kerogen. An increase of both Ea and pre-exponential factor was observed with an increasing heating rate. It is concluded that the mineral matter in oil shale enhances catalytic cracking as is evident from the reduced Ea values of oil shale compared with those for kerogen.     

废轮胎热解油的煤泥浮选试验

研究了废轮胎热解的规律和热解油作为捕收剂的煤泥浮选效果。试验结果表明：热解最终温度影响比较显著,而起始温度和保温时间对废轮胎热解油回收率影响不显著。FT—IR分析表明：东庞煤中含有大量的长链烃、芳香结构,还有-C=C-、-C=O、-OH、-SO2、-NH和-NH2。热解油中富含芳烃、烯烃、烷烃和一定量极性物。煤泥浮选表明：热解油作为煤泥捕收剂具有较强的捕收性能,同时还具有一定的起泡性能,可明显减少起泡剂用量。     

升温速率对鄂尔多斯煤裂解行为影响

对鄂尔多斯原煤和酸洗改性煤进行热分析,原煤热裂解主要经过三阶段,且在450~480℃阶段达到失重速率峰值。随着升温速率的提高,失重量也随之增加,且在快速热裂解阶段,失重速率也随之增加,经酸洗改性理后的煤样失重量大于改性前的煤样。     

The effect of heating rate on radical concentration during coal pyrolysis

The effect of heating rate on the change in radical concentration during coal pyrolysis has been studied using high temperature ESR with a rapid scan unit. The maximum radical concentration of Yallourn coal decreased with an increase in the heating rate. The results were compared with those obtained from a theoretical treatment of the kinetics of radical formation. The effect of a catalyst on the change in radical concentration has also been monitored under rapid heating condition. The maximum radical concentration of the coal/ZnCl₂ system showed a significant shift to temperature about 100 K lower than that of coal alone.     

Effect of pyrolysis pressure and heating rate on radiata pine char structure and apparent gasification reactivity

The knowledge of biomass char gasification kinetics has considerable importance in the design of advanced biomass gasifiers, some of which operate at high pressure. The char gasification kinetics themselves are influenced by char structure. In this study, the effects of pyrolysis pressure and heating rate on the char structure were investigated using scanning electron microscopy (SEM) analysis, digital cinematography, and surface area analysis. Char samples were prepared at pressures between 1 and 20 bar, temperatures ranging from 800 to 1000 °C, and heating rates between 20 and 500 °C/s. Our results indicate that pyrolysis conditions have a notable impact on the biomass char morphology. Pyrolysis pressure, in particular, was found to influence the size and the shape of char particles while high heating rates led to plastic deformation of particles (i.e. melting) resulting in smooth surfaces and large cavities. The global gasification reactivities of char samples were also determined using thermogravimetric analysis (TGA) technique. Char reactivities were found to increase with increasing pyrolysis heating rates and decreasing pyrolysis pressure.     

Effect of crude oil type and heating rate on combustion of crude oil-lignite mixtures

Research was conducted to investigate the possibility of upgrading low-quality lignites by mixing them with heavy crude oils. Three crude oil samples with API gravities of 12.9, 18.7 and 26.7 were mixed with lignite to form mixtures of 10 and 20% oil content. Thermal analysis experiments were conducted at non-isothermal heating conditions at heating rates of 5–100 K min⁻¹. Differential thermogravimetric data were analysed using an Arrhenius-type reaction model assuming a first-order reaction. The results indicate that the combustion of mixtures as observed on thermograms is very similar to that of lignite. However, the activation energy and reaction peak temperatures increased as the oil content in the mixture increased.     

温升速率对混合煤样热解的影响及动力学分析

为了节约动力煤,降低电力成本,为锅炉燃烧提供理论指导。采用热重分析法和热差分析法对褐煤和煤矸石的混合物进行热解实验。通过改变实验条件(温升速率)可以得到不同情况下的TG曲线、DSC曲线和转化率曲线。实验选用褐煤和煤矸石的质量比为2∶3,温升速率分别为10、30、50℃/min。10℃/min和50℃/min的煤样总的放热面积相近,但30℃/min的放热面积较小,说明30℃/min的温升速率不利于放热。由动力学分析得知,由于温升速率不同,活化能、频率因子均不同,热解动力学参数均发生一定变化。     

Influence of the pyrolysis heating rate on the steam gasification rate of large wood char particles

This work was carried out in order to quantify the impact of the pyrolysis heating rate both on the properties of the residual charcoal and on the behaviour during gasification by H₂O of the charcoal. The experiments were conducted on 10 mm diameter beech wood spheres, pyrolysed at atmospheric pressure under heating rates covering the range from very slow, 2.6 K min⁻¹, to very rapid, over 900 K min⁻¹, i.e. the highest value that can be reached. When charcoal is submitted to gasification at 20% H₂O in N₂ at 1200 K, the ratio of the times for complete conversion reach 2.6. Such a difference is considerable as far as an industrial application is concerned. The initial properties of the charcoal such as apparent density, porosity, and pore surface area obtained by N₂ or Ar adsorption were measured in order to explain the differences in gasification kinetics within the charcoal. The charcoal particles exhibit densities as different as 219–511 kg m⁻³ and porosities between 87 and 70% for charcoal prepared at 900 and 2.6 K min⁻¹ respectively. The specific surface area is higher than 600 m² g⁻¹ for three charcoals. Influence of ash content of the initial charcoals, at 1.6–2.7%, is also regarded with particular attention to explain the observed differences in gasification kinetics.     

油页岩微波热解气态产物析出特性

利用微波化学试验装置研究了油页岩微波热解过程中挥发分析出特性, 考察了微波功率、热解温度、不同热解温度阶段和催化剂对气体组成的影响。结果表明:微波加热能够提高油页岩热解气中H₂、CO和C₂H₄的析出, 降低CO₂的析出;50%(1600W)微波功率时烃类的析出量最大;在150~350℃的低温阶段热解气的析出量大, 主要由吸附气体的释放, 不稳定支链和基团的分解产生;温度升高, 气态产物的析出主要由脱氢、芳构化、缩聚和自由基反应产生。催化剂促进了气体的析出, 但不同类型催化剂对油页岩热解气组成的影响不同, 分子筛的吸附作用促进二次分解和缩聚反应;黏土类催化剂在质子酸作用下促进有机质催化裂解加氢反应, 加快断链和基团的稳定;金属类催化剂是强吸波性介质, 能够提高升温速率, 促进热解反应, 其次促进氢自由基的产生和转移。     

Oxidative pyrolysis of oil shale in tubular flow reactors with external heating

This article discusses the possibilities of the multipurpose use of oil shale based on the methods of their thermal processing. The main current concepts of oxidative pyrolysis processes are considered. A facility for the oxidative pyrolysis of powdered oil shale in tubular reactors of the gas-suspension type with external heat supply to the reaction zone is described.     

Effect of slurry heating rate on short-contact-time coal liquefaction

The effects of changes in heating rate of a coal/solvent slurry on conversions to pyridine-soluble material have been examined. Dramatic increases in conversions were observed when the coal/solvent mixture was maintained at a temperature of 589 K for 10 min before heating to reaction conditions of 700 K for 5 min. In particular, conversion increased from 32.0 to 76.7 wt % and the ratio of oils to preasphaltenes increased by a factor of four. The temperature range for the greatest effect is observed to be 550–595 K while 450 K shows no change in conversion. The mechanism is thought to be chemisorption of the solvent or solvent occlusion which would increase the concentration of hydrogen donor in the coal matrix thus affecting the reaction environment. Additional studies to further define the details of the programmed heating rate as well as explore the mechanism are needed.     

The significance of heating rate on char yield and char properties in the pyrolysis of cellulose

The carbonization of powdered cellulose was investigated in the temperature range 200–950°C by measuring weight loss, carbon and hydrogen content, BET-adsorption of nitrogen and carbon dioxide, mercury penetration and particle-size distribution. Evidence is presented in support of a kinetic model according to which cellulose decomposition is controlled by dehydration at low temperature and by cleavage/scission at high temperature. Increased char yield and lower $\text{O}\text{C}$ ratio at low heating rate, as well as kinetic investigations into the effect of potential catalysts, support this model. The difference in reaction mechanism according to the heating rate appeared to influence the char properties considerably. Yield in micropore volume and surface area of slowly carbonized cellulose is up to four times larger than that of rapidly heated cellulose. Mercury pore volume, density and particle diameter depend on the heating rate, also. By adsorption of various gases, differences in relative size of the pore openings of different chars can be discerned. Micropore volumes measured with carbon dioxide were as much as seventy times larger than the corresponding volume measured with nitrogen. Thus, it is possible to obtain chars with molecular sieve properties by simple pyrolysis heating schemes.     

典型杂质掺混对废塑料热解油特性的影响

以从4个典型的废弃物处理场取得的与废塑料掺混的杂质样品作为纯塑料热解过程中的添加剂,研究不可回收废塑料中掺混的杂质组分对塑料热解油品质的影响。研究内容包括4种杂质（I₁～I₄）对聚乙烯、聚丙烯、聚苯乙烯及混合塑料热解的影响以及杂质中的无机和有机组分在热解中分别起到的作用。结果表明,杂质的添加将塑料热解油中主要组分的富集度由65.5%提升到79.2%～90.3%;其中来源于废旧自行车拆解厂的杂质I₄对热解油组成的影响最为显著。I₄使得聚乙烯及聚丙烯热解油中的烯烃含量分别提高了25.0%及21.1%,但对聚苯乙烯的热解没有显著影响。I₄对塑料热解的影响可分为三个方面：无机灰分作为热载体起到的作用、特定活性灰分组分的催化作用以及杂质中有机组分参与热解的影响。灰分作为热载体促进了聚合物分子链的裂解;活性灰分组分能够催化加氢及氢转移等反应;而I₄中有机组分热解提高了油相产物中芳烃和烯烃的含量。该研究将为废塑料规模化热解过程中原料的预处理及热解油品质调控提供指导。     

碱金属对煤热解和气化反应速率的影响

通过对原煤、酸洗原煤、负载碱金属的酸洗原煤在800～1050℃热解制得焦样,用X射线衍射技术考察了碱金属对煤焦微晶结构的影响,在加压热天平（PTGA）上考察了煤样的热解过程,以及焦样的二氧化碳气化活性。结果表明：碱金属对煤的热解和气化阶段都有影响。在热解阶段,碱金属的存在抑制了煤焦的石墨化进程,降低了热解反应活化能,促进了热解反应的进行;在气化阶段,作为催化剂的碱金属,降低了气化反应活化能,延长了反应速率达到最大值的时间。修正的随机孔模型可以较好地描述煤焦-CO₂的气化反应过程。     

酸性糠醛残渣热解实验及热解炭性能研究

为解决糠醛渣的堆放及资源的合理利用,以糠醛渣为研究对象,分别在同步热分析仪及管式炉上进行热解实验研究,主要考察热解终温、升温速率、碳酸钠含量对糠醛渣热解产物分布及热解炭性能的影响。同步热分析仪分别以10—40℃/min的升温速率升高到850℃(10℃/min添加碳酸钠);管式炉上以10℃/min的升温速率到达热解终温300—600℃。结果表明:热重分析确定热解失重过程为干燥段、挥发分逸出段、热解炭化段3个阶段,确定主要热解温度区间为300—600℃。添加碳酸钠后抑制水分的析出,失重变化率峰值变大,表明碱金属钠盐促进纤维素的分解。随着热解温度的升高热解碳的p H值逐渐增大,热解温度为400℃时达到最高的亚甲基蓝脱色率44.4%。热解炭可进一步用于活性炭染料吸附。