油页岩半焦热解特性

利用热重分析仪对油页岩半焦热解特性进行了研究.综合考虑制取半焦所获得的页岩油品质、半焦成分、发热量和循环流化床设计,认为干馏温度介于500～600℃为宜;干馏度对半焦热解初析温度和低温段热解过程有影响,但对高温段热解影响不明显,高温干馏所制取的半焦其热解过程包含于低温所制取的半焦热解过程中;随升温速率的提高,相同温度下的半焦热解度降低,当升温速率超过40℃•min^-1后,升温速率对半焦热解过程影响不大;最后采用Coasts法计算了油页岩半焦热解动力学参数,计算结果可供数值仿真和工程设计参考.     

油页岩及其半焦混烧特性的热重试验研究和动力学分析

利用热重分析仪对桦甸油页岩燃烧时的双峰现象以及与其500℃半焦按不同比例混烧时单样相互影响程度、颗粒特性、着火温度和燃烧特性指数进行了考察;利用DAEM模型解析了混烧动力学参数。结果表明：油页岩燃烧DTG曲线在500℃附近的双峰活性参数值相差不大,分别为0.79和0.73,反映油页岩燃烧DTG曲线双峰归因于脂类有机质与干酪根中芳香烃的燃烧;混样中各单样在不同温度段相互影响程度不同,表观影响程度系数f的值均小于1。在燃烧过程中颗粒的缩核形状和表面分形维数并不是固定不变的,在低温段接近长圆柱体,在高温段接近平板,当浓度级次β=0.6时,低温段分形维数接近3,在高温段接近1;着火温度随半焦掺混量的增加呈线性递增;混样燃烧特性指数介于单烧之间并且存在掺混效果明显区;试样表观活化能在燃烧前期变化比较缓慢并呈下降趋势,大约在60～90 kJ·mol^-1之间,在后期剧烈增加,当转化率在0.60～0.75之间时表观活化能从80 kJ·mol^-1剧增到200 kJ·mol^-1。     

油页岩半焦燃烧反应活性分析

采用美国Perk in E lm er公司生产的Pyris1 TGA热重分析仪,对桦甸油页岩半焦进行燃烧特性试验研究,得到3种不同升温速率下的油页岩半焦燃烧特性曲线,并使用平均质量反应性指数和燃烧稳定性指数对半焦反应性加以评价。油页岩半焦燃烧分燃烧快速段、过渡段和燃烧慢速段3个阶段进行。随着升温速率的提高,在燃烧快速段,表观活化能为133.901 3—100.204 2 kJ/mol;在燃烧慢速段,表观活化能为146.317 1—211.409 3 kJ/mol。利用Coats-Redfern法确定了燃烧快速段反应级数为3,而燃烧慢速段则为5.5,从而得到油页岩半焦燃烧化学反应的动力学参数,为油页岩半焦的有效开发与经济利用提供了理论依据。     

抚顺油页岩半焦燃烧特性

为了提高油页岩半焦燃烧特性对以油页岩半焦氧化为主要热源的抚顺油页岩炼油工艺效率,利用扫描电镜与热重分析对450、550、650℃三种不同制焦温度下的抚顺油页岩半焦(J1、J2、J3),进行了表面形态和燃烧特性分析。结果表明,由于挥发分的析出,半焦表面结构变得粗糙,羽化现象严重。由于可燃物质随制焦温度上升析出较多缘故,半焦着火温度随制焦温度的上升而增高,在20℃/min升温速率下,着火温度由J1焦样的384.7℃升高到J3焦样的408.8℃。半焦的活化能在低转化率比在高转化率时要小,这主要是由于在高转化率下,可燃物减少,灰分热阻增加。     

Kinetics of tetralin extraction of Jordan oil shale

Isothermal kinetic data are obtained for the dissolution of Jordan oil shale in a hydrogen-donating solvent (1,2,3,4-tetrahydronaphthalene) in the temperature range 229–315 °C for untreated (as received mf) shale and 230–360 °C for the decarbonated shales. Preheating time was not accounted for in the treatment. For the untreated shale, the first-order plots have two distinct slopes at the lower temperature. For the higher temperatures, the plots fitted a single first-order expression. The activation energies were 42.6 and 85.6 kJ mol^?1 respectively. The data for the decarbonated shale fit a first-order expression with one low activation energy (E_a = 37.6 kJ mol^?1), suggesting a physical control of the dissolution process. Particle size variation showed a maximum yield at 200 mesh and smaller, although tests using large particles were hampered by settling. Solvent to shale ratios variation showed an optimum at about 180 g shale to 550 ml solvent. No effects of pressure of N₂ and H₂ upon the shale slurry yield were found. A reaction mechanism explaining the kinetic data is postulated.     

Study of pyrolysis kinetics of oil shale

The pyrolysis experiments on oil shale samples from Fushun, Maoming, Huangxian, China, and Colorado, USA, were carried out with the aid of thermogravimetric analyzer (TGA) at a constant heating rate of 5 °C/min. A kinetic model was developed which assumes several parallel first-order reactions with changed activation energies and frequency factors to describe the oil shale pyrolysis. The kinetic parameters of oil shale pyrolysis were determined on the basis of TGA data. The relationship between the kinetic parameters was further investigated and the correlation equations of x_∞-E and ln A-E were obtained. These equations show that the final fractional conversion of each parallel reaction, x_∞(j), can be expressed as an exponential function of the corresponding activation energy. The plot of ln A-E for different reactions becomes a straight line. These relationship equations can provide important information to understand the pyrolysis mechanism and to investigate the chemical structure of oil shale kerogen.     

AKTS模拟分析龙口油页岩与半焦混烧动力学特性

利用热重分析仪对龙口油页岩与其500℃半焦按照不同比例混合燃烧时着火温度和燃烧特性进行探究考察。基于3种升温速率下燃烧试验所对应的TG-DTG曲线,整个燃烧过程可分为3个阶段,分别为水析出阶段、燃烧低温段和燃烧高温段。不同比例样品的燃烧特性参数随掺入的页岩比例增大呈现出增大的趋势。利用AKTS-Thermokinetics软件对实验得到的DTG数据分析,对比实验曲线与模拟曲线,并进行反应动力学的计算。基于计算结果发现,随着样品中油页岩的比例增大,活化能呈现出先减小后增大的趋势。综合各样品燃烧特性参数,发现页岩与半焦比例2：1为当前燃烧试验最优混合比。     

小颗粒油页岩及半焦CFB锅炉燃烧适应性研究

油页岩经低温干馏可以得到页岩油,因生产工艺限制,干馏炉无法使用粒径12 mm以下的油页岩,同时会产生大量副产品(页岩半焦)。为提高副产品的利用能力,实现资源利用最大化。通过在1 MW_(th)CFB燃烧试验台对小颗粒页岩及页岩半焦进行试烧试验,研究小颗粒页岩及页岩半焦的理化特性、着火特性、燃尽特性、结焦特性。试验结果表明,控制床温在720~850℃内,由油页岩小颗粒和半焦掺混而成的设计燃料在试验台采用CFB方式能够稳定燃烧,试验各工况灰渣含碳量均低于1.81%,试验燃料较易燃尽。CFB锅炉适合油页岩小颗粒与半焦掺烧利用,且燃烧效率高,燃烧稳定性较好。     

油页岩半焦燃烧动力学研究

燃烧动力学是研究油页岩半焦颗粒燃烧特性的基础。利用热重分析仪对油页岩半焦进行了恒温燃烧实验研究,在排除外扩散影响的基础上,分析了燃烧温度、氧气浓度对油页岩半焦燃烧过程的影响。在实验范围内,氧气浓度和燃烧温度均能对油页岩半焦燃烧速率产生重要影响,更高的氧气浓度和燃烧温度可以加快油页岩半焦燃烧速率。结合实验结果,建立了考虑氧气浓度影响的油页岩半焦燃烧动力学模型,发现油页岩半焦燃烧速率与氧气浓度的0.97次方呈线性关系。模型计算结果与实验结果符合较好,为进一步研究油页岩半焦大颗粒燃烧特性提供了燃烧动力学基础。     

油页岩半焦作为水泥混合材的可行性研究

选取4种热解温度(300 ℃、400 ℃、500 ℃、600 ℃)半焦,通过扫描电镜(SEM)对油页岩半焦的微观结构进行分析,然后采用油页岩半焦等质量(0%、5%、10%、15%、20%、25%)替代水泥,测试标准稠度需水量、胶砂流动度和不同龄期的水泥胶砂的抗折、抗压强度。结果表明:油页岩半焦呈层片状、且表面多孔,随着热解温度的升高,微孔和小孔数量逐渐减少,中、大孔数量增加;掺入油页岩半焦会增加水泥标准稠度需水量,降低胶砂流动度,半焦替换量和水泥标准稠度需水量之间存在较强的线性关系;随着油页岩半焦热解温度的升高,水泥胶砂抗折和抗压强度先增大后减小,在500 ℃时力学性能达到最佳;随着油页岩半焦替换量的增加,水泥胶砂抗折和抗压强度都逐渐降低,当油页岩半焦替换量为15%时,500 ℃热解半焦水泥胶砂56 d力学性能与P·Ⅰ 42.5基准水泥胶砂接近。     

A kinetic and mechanistic comparison for Jordan oil shale pyrolysis and dissolution

Jordan shale pyrolysis at temperatures ranging from 280 to 518°C has been compared with thermal dissolution at temperatures from 230 to 315°C. The samples undergoing reactions were also compared when decarbonated (HCl treated shale), to verify the catalytic effects of the inorganic mineral matter.Pyrolysis reactions were studied by isothermal weight loss and non-isothermal decomposition experiments. The shale underwent softening and molecular rearrangement with a small but detectable weight change, from gaseous desorption up to 300°C. Then the kerogen began to fragment, yielding high molecular weight hydrocarbons which were evolved as volatile matter up to a temperature of about 500°C. The kinetics of both processes followed a first-order relation with time and gave an activation energy of 38.5 kJ/ mole which is well in the range of a diffusion controlled reaction. The yields were up to 23% by weight of untreated shale and 42% of decarbonated shale.For dissolution conversions of up to 90 percent by weight of shale organic matter was attainable at temperatures in the range of 315°C. The Arrhenius plot was resolved into two straight lines; one corresponding to diffusion control (E_a = 42.6 kJ/mole) and the second beginning at T = 275° with E_a = 85.6 kJ relating to cracking and hydrogenolysis of aromatic clusters. For decarbonated (carbonate-free) shale, the kinetics were first-order throughout, with E_a = 37.6 kJ/mole.The extent of kerogen sulfur removal reactions with tetralin was checked by analyzing for sulfur content in oil extract and residue. The sulfur concentrations of the gases were obtained by difference. The C/H ratios of extract and pyrolysis oil were determined to verify solvent effects.A mechanism is suggested which relates the kinetics to the transformation of kerogen to oil, gas and coke.     

DTA derived kinetics of Jordan oil shale

The thermal behaviour of Jordan oil shale has been studied in a DTA apparatus in an He atmosphere. The thermal curves for both untreated and decarbonated shale exhibited two distinct endothermic peaks related to the softening and evolution of organic matter. The first peak relates to molecular rearrangement of the kerogen where nonisothermal kinetics found that the activation energy (E_a) in the range 13.4–25.1 kJ mol^?1 for both untreated and decarbonated samples. For the second peak, E_a was obtained from first order kinetics and varied from 54.9 kJ mol^?1 for decarbonated shale to 79.6 kJ mol^?1 for untreated samples. The effect of particle size on the DT curves was studied and showed a drift from zero base line. Spent shale for reference material improved the profile of DTA curves and minimized drift as compared to use of α-alumina.     

Miscibility and crystallization behavior of poly(ethylene-co-vinylalcohol)/poly(maleic anhydride-alt-ethylene) blend

The miscibility of poly(vinylalcohol-co-ethylene) (PEVA) with poly(ethylene-alt-maleic anhydride) (PEMAH) blends was investigated over a wide range of compositions by viscosimetry and DSC analyses using Krigbaum–Wall and Kwei approaches. The results revealed that the blends were completely miscible in all proportions due to the specific interactions between the hydroxyl groups of PEVA and the carbonyl groups of PEMAH. From Nishi equation, the interaction parameter of Flory was found to be −0.89. The nonisothermal crystallization behavior and kinetics of this system were also investigated and compared with those of the pure PEVA. There were strong dependencies of the degree of crystallinity (X_T), peak crystallization temperature (T_p), half time of crystallization (t_1/2), and Ozawa exponent (m) on PEMAH content and cooling rate. The crystallization activation energy (E_c) that was calculated from Kissinger model increased with increasing PEMAH composition in the blend. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

油页岩半焦与煤混合燃烧特性研究

采用热重分析仪对油页岩半焦与不同煤化程度的煤混合燃烧特性进行动态分析,讨论了掺混煤种和比例对燃烧过程的影响.结果表明,燃烧特性好的煤种可以改善页岩半焦燃烧特性,额吉长焰煤是最佳掺混煤种,随着煤掺混比例的提高,混合物燃烧特性指数增大.     

Thermal degradation of shale oils: 1. Kinetics of vapour phase oil degradation

As vertical modified in-situ retorts (VMIS) have been scaled up and tested, the overall oil yield has declined and is generally lower than that observed in an above-ground process. This reduced oil yield could adversely affect the economics of VMIS retorting. Diminished yields are attributed to a combination of factors associated with scale-up such as in complete rubblization, wide particle size distributions (large blocks of shale), and poor flow distributions. Additionally, oil losses can occur by comparatively long exposure of the oil vapours to high temperatures, by exposure to successive condensation and revaporization of the oil as it travels down the retort, and finally by long time thermal exposure of the condensed oil retained in the bottom portion of large VMIS retorts. To study such vapour phase degradation of shale oil using oil produced from Occidental Petroleum's No. 6 VMIS retort, a tubular continuous flow reactor, with an on-line gas chromatograph for gas composition monitoring was used to study thermal degradation of shale oil under retorting conditions. Oil and a combination of gases including steam were metered into the preheater and then the vapours passed into a quartz tubular reactor where the temperature and residence time of the gaseous mixture were controlled. Complete mass balances were performed giving the weight fraction of oil converted to noncondensable hydrocarbon gases and coke. This experimental design is novel because high temperature thermal degradation of shale oil was studied for the first time under steady state flow conditions with carefully controlled residence time and temperature. A range of temperatures (425–625 °C) and residence times (2–10 s) were used in a series of factorial-designed experiments (3²) to accurately determine the effects of these variables. Results of the study showed that the addition of steam to the carrier gas did not reduce oil degradation losses but did react with the coke thereby changing the product gas composition and quantity. A first-order oil degradation rate expression was used to model the rate of oil loss. The calculated activation energy was 17.3 kcal mol^?1. Chemical analyses of the product liquids and gases confirmed previously reported findings that the oil loss indices (alkene/alkane, ethylene/ethane, naphthalene/(C₁₁ + C₁₂), and gas/coke) increase with increasing oil degradation.     

Thermogravimetry and decomposition kinetics of British Kimmeridge Clay oil shale

The characteristics of volatile matter evolution and the kinetics of thermal decomposition of British Kimmeridge Clay oil shale have been examined by thermogravimetry. TG has provided an alternative to the Fischer assay for shale grade estimation. The following relation has been derived relating TG % volatiles yield to the shale gravimetric oil yield: oil yield (g kg^?1) = (TG volatiles, % × 5.82) ? 28.1 ± 14.5 g kg^?1. A relationship has also been established for volumetric oil yield estimation: oil yield (cm³ kg^?1) = (TG volatiles, % × 4.97) – 5.43. TG is considered to give a satisfactory estimation of shale oil yield except in certain circumstances. It is found to be less reliable for low yield shales producing <≈40 cm³ kg^?1 of oil (≈10 gal ton^?1) where oil content of the TG volatiles is low: volumetric yield estimation accuracy is affected by variations in shale oil specific gravity. First order rate constants, k = 4.82 × 10^?5s^?1 (346.3 cm³ kg^?1shale) and k = 6.78 × 10^?5s^?1 (44.6cm³ kg^?1shale) have been obtained for the devolatilization of two Kimmeridge oil shales at 280 °C using isothermal TG. Using published pre-exponential frequency factors, an activation energy of ≈57.9 kJ mol^?1 is calculated for the decomposition. Preliminary kinetic studies using temperature programmed TG suggest at least a two stage process in the thermal decomposition, with two maxima in the volatiles evolution rate at ≈450 and 325 °C being obtained for some samples. Use of published pre-exponential frequency factors gives activation energies of ≈212 and 43 kJ mol^?1 for these two stages in the decomposition.     

A comparison of the reactivity of various metal oxides with SO3

Various metal oxides were reacted with SO₃ to compare their reactivity as potential adsorbents of sulfur oxides from flue gas. ZnO was found to be the most reactive of the eleven studied, including two mixtures, a fly ash and a calcined oil shale. It was found that a scanning electron microscope can be used to assess the reactivity of the oxide based on a rough estimation of internal pore structure from the micrograph of the particles.     

桦甸油页岩的微波干馏特性

在自行设计的微波干馏装置上研究了桦甸油页岩、半焦及其混合物在微波场中的升温特性。发现油页岩本身是一种微波弱吸收物质,纯油页岩在微波场中升温能力较差;油页岩热解产物半焦在微波场中升温很快,可以作为油页岩微波干馏的微波吸收剂,将油页岩和半焦的混合物放入微波场中能达到良好的热解效果。实验研究了半焦和油页岩的混合比、微波功率、粒径等因素对微波干馏效果的影响,结果发现,随着半焦比例加大,产油率增加,半焦产率降低;在相同时间内,微波功率越大,产油率和气体损失产率越大,半焦产率降低;油页岩粒径对微波热解影响较小,但当粒径小于0.2mm时实验中出现了较严重的夹带现象。     

Emissions monitoring during coal waste wood co-combustion in an industrial steam boiler

Co-combustion tests were performed in a 13.8 MW_th industrial steam boiler, using Greek lignite from Ptolemais reserve, natural waste wood, MDF residues and power poles. Fuel blends were prepared by mixing single waste wood components with lignite in various concentrations. Oxygen concentration and emissions of CO, SO₂ and NO_x were continuously monitored, during the co-combustion tests. Gaseous and particulate samples were collected and analysed for heavy metals, dioxins and furans according to standard methods. The results showed that co-combustion is technically feasible provided that agglomeration problems could be confronted. Low emissions of toxic pollutants were obtained during the co-combustion tests, below the legislative limit values. The lowest values of dioxins and furans were observed during combustion of fuel blends containing MDF, possibly due to inhibition by some nitrogenous components in MDF. No direct correlation was found between emitted PCDD/F and metal compounds, especially copper. Among the measured metals in the flue gases, zinc was the most prominent, while iron was mainly observed in the solid ash samples.     

Dispersion parameters of cadmium chloride doped PVA-PVP blend films

Solution cast films of poly vinylalcohol (PVA) – poly vinylpyrrolidone (PVP) polymer blend, doped with different concentrations (from 0.5 wt% up to 40 wt%) of cadmium chloride (CdCl₂) have been studied by analysing the data recorded using optical (UV-Vis) spectrometry. The modified band structure of PVA -PVP blends doped with CdCl₂ has been studied using Moss model and Wemple - DiDomenco model. Optical parameters such as transmittance (T), reflectance (R), refractive index (n), average oscillator energy (E₀), oscillator dispersion energy (E_d), real and imaginary part of dielectric constant (ε_r and ε_i) have been determined. The ratio of charge carrier concentration to effective mass (N/m^*), plasma frequency (ω_p), average oscillator wavelength (λ_o), oscillator strength (S_o), optical conductivity (σ) and optical momenta of spectra (M_?1 and M_?3) have been estimated for the PVA-PVP blend films doped with CdCl₂.