Low temperature oxidation of athabasca bitumen

The kinetics of low temperature oxidation in the Athabasca oil sands were investigated over the temperature range 373 K to 459 K. Oxidation experiments, in which the sand-free bitumen was vigorously stirred to obtain a homogeneous oxygen concentration throughout the bitumen, were carried out. It was concluded that the oxidation reaction is governed by three different kinetic expressions depending on temperature and past oxidation history. These are: (i) a high rate first order regime which is obeyed at low extents of oxidation and at temperatures below approximately 423 K; (ii) a second order regime, obeyed at low extents of oxidation and at temperatures greater than 423 K; and (iii) a low rate first order regime, obeyed for extents of oxidation greater than 1.7 moles O₂/kg bitumen over the entire temperature range investigated. The partial molar enthalpy of low temperature oxidation was also evaluated, and was found to be constant over the range of oxidation extents studied.     

脱硫用电石渣浆液中硫化物去除工艺的对比研究

分别研究了空气催化氧化法、双氧水氧化法和漂白粉氧化法对脱硫用电石渣浆液中硫化物的去除效果。实验结果表明,在适当条件下,空气氧化法可在240 min内使硫化物的去除率达到80%,适量的双氧水和漂白粉能够使硫化物降至0.5 mg/L以下,去除率达到99%以上。在此基础上对比了3种工艺的经济成本:空气催化氧化法<漂白粉氧化法<双氧水氧化法。     

Diffusion coefficients of propane and butane in peace river bitumen

Diffusion plays a vital role in the “Vapex” process. In the present work the results of experiments on “Vapex” using a Hele-Shaw cell have been used to obtain empirical correlations for the diffusivities of propane and butane in Peace River bitumen. Additional data required for the estimation of diffusivities from these experiments are the solubilities of solvent in bitumen and a correlation for the viscosity of solvent bitumen mixture. Diffusivities are assumed to decline exponentially with viscosity. Computed values of diffusion coefficients fall within the range of the published data for similar systems. This simple experiment can be used to estimate the diffusivities of gaseous solvents in highly viscous fluids.     

Oxidation of low concentrations of hydrogen sulfide by air on a fixed activated carbon bed

As part of a study to evaluate the performance of a “dry” catalytic method of removing low concentrations of H₂S from cupola gas, the rate of oxidation of low concentrations of H₂S by air at room temperature has been studied using a fixed activated carbon bed. Previous studies have presented somewhat contradictory results. It was found that the rate decreased with time, consistent with a rapidly fouling catalyst, and finally attained a steady state value. A mechanism is presented which is in agreement with the results. The oxidation rate was also found to increase drastically by increasing the air humidity, contrary to the published results of some other workers.     

Assessment of Bitumen Re c overy from the Athabasca Oil Sands Using a Laboratory Denver Flotation Cell

A methodology was developed in this study to evaluate the effect of operating parameters on the processability of oil sands using small‐scale laboratory experimental devices. By subtracting bitumen recovered to the froth by entrainment with water, the concept of “true flotation recovery” is proposed to describe bitumen recovery resulting from bitumenbubble attachment. The experimental results indicated that “true flotation recovery” is a more sensitive and meaningful marker than overall bitumen recovery to evaluate the processability of oil sands using small‐scale laboratory test units.     

微晶蜡无催化剂氧化的研究

对微晶蜡无催化剂氧化改性工艺进行了研究，考察了反应温度，空气流量和反详时间对微晶蜡氧化过程的影响，并对氧化微晶蜡产品进行了红外分析，结果表明，不采用催化剂，适当提高反应温度，不但能对微晶蜡进行快速氧化，而且能够得到性能优良的氧化微晶蜡产品。     

湿式空气氧化技术处理乙烯裂解废碱液试验研究

采用湿式空气氧化工艺处理乙烯裂解废碱液,系统研究了不同反应温度和停留时间对该类废碱液处理效果的影响。结果表明,在湿式氧化过程中S2-的氧化相对容易,当反应温度不低于190℃时,S2-去除率为100%,当反应温度小于150℃时,S2-的存在形式以S2O32-为主,反应温度达到230℃时,S2-基本完全转化成SO42-;废碱液中COD的去除率随反应温度的升高而增加,当反应温度为230℃时,其去除率可达80%以上。     

本质安全化设计在硝酸氧化醇工艺中的应用

硝酸氧化醇的反应大多为强放热反应,具有很高的反应热失控危险性。本文在本质安全原理的指导下,结合工艺热危险性分析理论,提出通过适当提高反应温度、改变反应混合性以及强化反应器加料模式3种设计方案来降低硝酸氧化仲辛醇反应工艺的危险性,改善工艺本质安全化水平。同时,根据本质安全评估指标及赋值方式,构建出本质安全化设计影响度的评估模型,并利用该模型验证了3种设计方案对于提高该工艺本质安全化程度的合理性。结果表明：适当提高反应温度、改变反应混合性、强化反应器加料模式分别使该工艺的本质安全化程度提高了约11.7%、12.8%、10.7%。同时,本文提出的3个设计方案在提高该工艺本质安全化程度上主要体现在“最小化”和“缓和”这两个本质安全原理上。     

The co-processing of coal with heavy feedstocks

When coal is processed with bitumen, heavy oils and petroleum residua there is a technological and economical advantage over conventional liquefaction processes. “Current coal” liquefaction concepts use, as vehicle, a coal-derived oil to react with coal, but because two-thirds of the coal-derived oil must be recycled, the throughput efficiency of these processes is low. In contrast, using bitumen, heavy oils and residua as vehicles to process coal is a “once-through” process. The data show that bitumen, heavy oils, residua and related liquids can be used to liquefy coal, and that the extent of liquefaction and the yields of distillable oils vary and depend upon the type of solvent and process conditions. Some of the co-processing options involve catalysts made of transition metals, such as nickel, cobalt, iron and molybdenum. However, the development of better catalysts and additives should be pursued to increase the production of high quality liquid fuels.     

Continuous gas–liquid aerobic oxidation of toluene catalyzed by [T(p-Cl)PPFe]2O in a series of three stirred tank reactors

The liquid-phase catalytic aerobic oxidation of toluene by [T(p-Cl)PPFe]₂O was studied in a series of three stirred tank reactors. The effects of operation mode (including semi-batch and continuous operation), reaction temperature, catalyst concentration, average residence time, and air flow rate on the oxidation process were examined. The experimental results showed that continuous oxidation had no advantage over the total yield and selectivity of benzaldehyde and benzyl alcohol in comparison with semi-batch oxidation. And the reaction temperature was the most significant factor influencing on continuous oxidation of toluene. It is also found that adopting sequentially decreased temperature in the three series reactors could improve the yield and selectivity of benzaldehyde and benzyl alcohol in this process. Under which at the higher conversion of toluene, the total yield to benzaldehyde and benzyl alcohol increased 17.05% or 43.62% respectively in comparison with adopting sequentially increased or same temperature in the three series reactors.     

Processibility of Athabasca Oil Sand Using a Laboratory Hyd ro t ransport Extraction System (LHES)

A novel laboratory scale apparatus has been developed and used to assess the extraction performance of oil sands under conditions analogous to current industrial processes. The apparatus can be used to investigate independently, the liberation of bitumen from the sand as well as air‐bitumen attachment and bitumen recovery. Experiments show that lower operating temperatures have a detrimental effect on bitumen recovery and controlled air addition is beneficial for recovery. The liberation of bitumen from sand grains has been found to proceed faster than air attachment and bitumen recovery, making the flotation the ratelimiting step in the extraction process. The potential benefit of staged air injection into hydrotransport pipelines as a possible process aid is discussed.     

Accelerated deactivation of medium-temperature lignite coke

Efforts are made to eliminate the self-heating and self-ignition of medium-temperature coke produced from Kansk-Achinsk brown coal (lignite) in a fluidized bed via “Termokoks-KS” technology. The optimal conditions of accelerated coke deactivation are found. The deactivation process is based on the low-temperature oxidation of coke by the surrounding air. Deactivation may be greatly accelerated at temperatures close to the critical temperature at which ignition occurs for samples of the given material.     

Kinetics of the thermo-oxidative and thermal cracking reactions of Athabasca bitumen

The thermo-oxidative and thermal cracking reactions of Athabasca bitumen were examined qualitatively and quantitatively using differential thermal analysis (DTA). Reaction kinetics of low temperature oxidation (LTO) and high temperature cracking (HTC) were determined. The rate of the LTO reaction was found to be first order with respect to oxygen concentration. The activation energy and the Arrhenius pre-exponential factor were 64 MJ kg^?1 mol^?1 and 10^5.4 s^?1, respectively. The effects of atmosphere, pressure, heating rate and support material on the thermal reactions of bitumen were studied. In general, it was found that partial pressures of oxygen > 10% O₂ favoured exothermic oxidation reactions. High pressure increased the rates of LTO and HTC as well as the exothermicity of these reactions. A major contribution of this study to thermal in-situ processes is that heating rate can be used effectively to control the extent of low temperature oxidation and hence fuel availability during in-situ combustion. Low linear heating rates (2.8 °C min^?1) favoured low temperature oxidative addition and fission reactions. The reaction products readily formed coke and combusted upon heating. High linear heating rates (24.5 °C min ^?1) led to rapid oxidation reactions in the high temperature zone; the high temperature and the energy released during oxidation appeared to promote combustion. Finally, when sand was used as the support material there appeared to be a catalytic effect in both LTO and HTC reactions.     

Viscous characteristics of a Utah tar sand bitumen

The viscous behaviour of an extracted tar sand bitumen has been experimentally examined and the results summarized in this Paper. The material studied was from the Asphalt Ridge, Utah area. The viscosity of the bitumen has been determined as a function of temperature (293–422 K), toluene (solvent) content (0–10%), composition (0–14.6% asphaltenes), oxidation and shear history. In all cases studied, the Arrhenius plots were significantly non-linear at temperatures s> 373 K, with viscous behaviour becoming less sensitive to toluene content with increasing temperature. Low temperature behaviour was strongly dependent on toluene content. The presence of asphaltenes in the bitumen was shown to be a strong viscosity enhancer. Oxidation and shear history were also shown to measurably increase the bitumen viscosity.     

Crack Healing by Thermal Treatment in Float Glass: The Effect of Tin

The evolution of radial cracks generated by Vickers indentation on “tin side” of float glass is analyzed when heat treated at 620°C under various atmospheres and results are compared with a previous similar study performed on the “air side” of the same glass. Results evidence that the presence and the oxidation state of tin ions has a strong influence on crack morphological changes. If the oxidation state of tin remains quasi unchanged during the heat treatment, the mechanism responsible of the crack evolution is the spheroidization and there is no strong difference between the crack morphological changes observed on the “air” and “tin side” in this case. For oxidative atmospheres, contrary to what is observed on the “air side”, no crack spheroidization occurs. The cracks stay quasi unchanged for dry air or close for humid air. Increase of the viscosity at the top surface due to Sn oxidation is proposed to explain this spheroidization impediment. It is also shown that in these two cases, there is an efficient blunting and healing of the cracks, as 4‐point bending tests indicate a significant sample strengthening with thermal treatment.     

Impact of cooling method and incoming sheet quality on final part surface quality in thick sheet paint film thermoformed parts

Thick sheet, “dry paint” film parts were thermoformed using different cooling methods and sheet temperatures to determine whether these two parameters had a direct effect on the surface quality of the final part. Although some thermoformers have claimed that applying chilled air after forming “dry paint” film parts improves the gloss of the parts, the data from this study showed that application of chilled air did not have an effect on either the parts' initial gloss or their gloss after time‐dependent hazing. The critical factor in maintaining surface quality in these parts was the maximum temperature reached by the “dry paint” film during heating. In addition, analysis of the data taken on the sheet prior to forming versus that taken on the part after forming demonstrated the importance of validating the surface quality of the as‐received sheet prior to conducting process versus appearance experiments. On the basis of these findings, a recommendation is made for incoming sheet surface quality levels for both process development studies and production applications. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

饮用水中隐孢子虫与贾第虫的危害及其去除灭活研究

本文在介绍"两虫"即贾第虫和隐孢子虫的生态、危害及传播的基础上,综述了常规水处理工艺、膜法及组合工艺对"两虫"去除效果;分析了各种消毒剂和消毒方法灭活的优缺点,提出多种方法协同灭活将成为水消毒技术研究和开发的一个发展方向。预处理、絮凝、沉淀、澄清和过滤等常规水处理单元不能有效去除两虫,难以保证饮用水安全;膜过滤法两虫去除效率高,但大规模应用困难较大。而常规的氯消毒剂灭活两虫的效果不佳,臭氧对两虫的灭活效果优于氯和二氧化氯;UV能有效灭活两虫,但穿透力弱,UV灯管寿命短,运行费用高;US灭活两虫,能耗比较高。单一的消毒剂灭活两虫效果欠佳,采用多种消毒剂(方法)联合使用,通过协同作用,可达到较高的灭活率。     

Coking of athabasca bitumen: effect of oxidation and sand

The effect of low temperature oxidation on the ultimate coke residue from Athabasca bitumen was examined quantitatively for extents of oxidation up to 100 mg O₂/g bitumen. The residue yield was found to increase linearly with extent of oxidation. When sand was introduced during the oxidation or pyrolysis processes, a smaller increase in coke yield was observed.     

Ultrasound-assisted convective drying of apples at different process conditions

ABSTRACT

The aim of this article was to study the influence of drying parameters like air temperature and velocity on the effectiveness of convective (CV) and ultrasound-assisted convective drying. The apple samples were used as the testing material by drying at air temperatures of 313 and 323?K and three different air velocities: 2, 3, and 4?m/s. The drying kinetics, the quality of dried products, and the energy consumption in each drying process were analyzed. The model of drying elaborated by authors was performed to estimate numerically the effect of ultrasound enhancement of convective drying. It was found that application of ultrasound significantly accelerates the CV drying, mainly due to “vibration effect,” and the values of drying parameters like air temperature and velocity affect the drying effectiveness in a different way.     

Two‐step consecutive reaction model and kinetic parameters relevant to the decomposition of Chinese forest fuels

Decomposition of some Chinese forest fuels has been studied by means of nonisothermal thermogravimetric analysis in oxidative and inert atmosphere at low heating rates. A comparison between thermogravimetric curves obtained in air and nitrogen shows that the existence of oxygen enhances the decomposition rate and changes the mechanisms of thermal degradation. After the water evaporation, two well‐defined decomposition stages have been observed in thermogravimetric curves obtained in air, which correspond to oxidative degradation of main components and oxidation of char formed. A kinetic model named “two‐step consecutive reaction model” is developed to describe the thermal degradation process of these materials in air, and there is a good agreement between the experimental and calculated thermogravimetric and derivative thermogravimetric curves. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 571–576, 2006