浆态床重油改质技术新进展

浆态床加氢工艺是一种重要的劣质重油/渣油轻质化技术,随着原油的劣质化和产品的清洁化,其重要性凸显,各大石油公司均大力研究和开发。本文重点介绍了典型浆态床加氢工艺(包括Eni公司的EST、Chevron公司的VRSH、UOP公司的UniflexTM等)的技术特征和进展情况。在详细分析浆态床加氢反应机理的基础上,指出了其未来的研究方向:研究重油反应过程的胶体稳定性以控制生焦;开发新型高效催化剂以降低成本;研究浆态床反应器流体力学和传质特性以指导工程放大。     

Review of processes for downhole catalytic upgrading of heavy crude oil

Unlike conventional refinery processing, downhole upgrading involves implementing catalytic processes in oil-bearing geologic formations. In this way impurities contained in heavy crude oil can possibly be left in the ground or easily separated during oil production, providing an improved crude oil feed for refineries. Additionally, value or viability can be added to an otherwise uneconomic or remote heavy oil deposit. In order to successfully produce improved quality oil via a downhole upgrading project, several processing steps are anticipated: placement of catalysts into an appropriate downhole location, mobilization of reactants over the catalyst bed, and creation of processing conditions necessary to achieve a reasonable degree of catalytic upgrading. Each of these steps has been proven by past application; their combination into a unified below-ground process remains problematic. Downhole processing differs from surface processing in that brine, high steam partial pressures and low hydrogen partial pressures need to be accommodated in the downhole setting. There are no reports of significant downhole catalytic upgrading of crude oil, although examples of thermal upgrading are noted. However, available technology should be amenable to conducting a successful process. Upgrading of heavy crude oil at anticipated downhole processing conditions has been successfully proven in the laboratory. Recently published literature with immediate pertinence to the problems of downhole catalytic upgrading is reviewed with the goal of stimulating research and providing directions for future investigations.     

In situ upgrading of bitumen and heavy oils via nanocatalysis

Thermal in situ bitumen production has introduced a different engineering approach compared to conventional oil exploitation. Steam injection for example, allows the development of a relatively confined liquid and gas chamber surrounding and along the length of the production wells. This heated place can be converted into a reactor for upgrading processes founding expectations of extensive reservoir upgrading of unconventional oils reducing the total energy currently required to both exploit the reservoir and surface upgrade the produced bitumen. These could also selectively transform contaminants into harmless products remaining in the reservoir. This article highlights the nanocatalytic in situ upgrading paths that may result in economical and environmentally efficient oil sands exploitation. © 2012 Canadian Society for Chemical Engineering     

The use of coal liquefaction catalysts for coal/oil coprocessing and heavy oil upgrading

The catalytic hydrogenation of heavy oil and mixed coal-heavy oil (coprocessing) systems has been the focus of a recent study at the Federal Energy Technology Center (FETC). The intent of this effort was to extend the use of coal liquefaction technologies to heavy oil upgrading and coprocessing systems. Specifically, new dispersed molybdenum-based catalysts developed at FETC and a novel silica-doped hydrous titanium oxide (HTO : Si)-supported NiMo catalyst developed at Sandia National Laboratories (SNL) were tested in these systems. The results indicate the potential of coal liquefaction catalysts for use in coprocessing and heavy oil upgrading. High conversions of coal–oil mixtures were observed with dispersed catalyst loadings as low as 100 ppm Mo. Similar results were observed in heavy oil systems. Also, the novel NiMo/HTO : Si catalyst was at least as effective as commercially-available supported catalysts (e.g. Amocat 1C) for conversion of high boiling point material to distillable products and aromatics removal.     

Process intensification for heavy oil upgrading using supercritical water

Demand for light hydrocarbons has been steadily increasing in the market with a corresponding decrease in heavy hydrocarbon demand. Therefore, there is a need to develop environmentally friendly and efficient technologies for conversion of heavy molecular weight hydrocarbons. Supercritical fluids (SCF) are attracting increased attention as solvents for green chemistry and among those supercritical water (SCH₂O) is promising for the upgrading of heavy hydrocarbons. Because of a sharp decrease in its dielectric constant, water loses its polarity when brought to the supercritical conditions and its properties starts to resemble the properties of hydrocarbons and becomes an excellent solvent for organic compounds. Moreover, increased ionic product of water leads to an increasing [H₃O⁺] concentration and thus promotes the reactions requiring the addition of an acid. Solvation power enables the extraction of lighter compounds while increased [H₃O⁺] concentration makes the reactive extractions of heavy hydrocarbons possible. As a result of its favorable properties, a wide variety of process intensification studies have been carried out using near critical or SCH₂O such as combined distillation-cracking-fractionation and in some cases even without the utilization of catalysts and/or hydrogen. In this review, recent advances on reactions of hydrocarbons occurring in a SCH₂O environment will be highlighted. Fundamental aspects of these reactions including their thermodynamics and kinetics will be discussed. Experimental and theoretical developments on phase equilibria of relevant water–hydrocarbons systems will be presented.     

沸腾床渣油加氢处理催化剂失活研究

沸腾床催化剂失活主要是由于金属和焦炭沉积导致的,同时在沸腾状态下催化剂的物理和机械性质也发生了改变。使用后的催化剂向小的粒度分布方向偏移;催化剂沉积了大量的金属和焦炭,使催化剂的堆积密度增加,同时导致催化剂的孔结构、酸性质发生了变化。失活催化剂沉积的金属和焦炭在颗粒内外分布均匀,表明催化剂利用率较高。     

稠油地下改质开采技术及发展趋势

稠油作为全球重要的非常规原油资源,是保障我国能源安全、重大工程需求的重要资源。目前常规的热采稠油油藏陆续进入开采后期,高能耗、高污染、高成本问题日趋严重,亟需依靠技术换代实现开发方式升级。稠油地下改质是通过向油藏中注入改质催化剂,使其与稠油发生化学反应,实现稠油地下不可逆降黏并高效采出的一种开采方式,是近十年来最受瞩目的下一代稠油开采技术之一。本文从技术机理、改质催化剂及开采效果影响因素三方面阐述了技术内涵,通过系统调研国内外相关学者和企业的代表性成果,按照催化剂种类、反应温度和降黏效果等进行综合性分类统计,对比了现有矿场试验的开采方式和采油效果,指出制约技术应用的两个关键问题,并展望了技术未来发展方向。     

Kinetic modeling of hydrocracking of heavy oil fractions: A review

An exhaustive review of the scientific literature on kinetic modeling of heavy petroleum fraction hydrocracking is reported in this paper. Kinetic models for hydrocracking of model compounds were not analyzed. The review includes models based on the lumping technique, continuous mixtures, structure oriented lumping, and single event models. Experimental data, reaction networks, main characteristics of kinetic approaches, and kinetic parameter values are also reported. In some cases when detailed experimental data were available, kinetic parameters were re-estimated and some differences were found in comparison with original reported values. One representative model of each kinetic approach was selected, and parameter estimation was done with reported experimental values in order to establish the capability and accuracy in the prediction of conversion and product yields. Advantages and disadvantages of the models are discussed in terms of their capability to predict detailed product composition, difficulty for parameter estimation, dependency of rate coefficient with feed properties, and required experimental data.     

Structure and thermodynamic consistency of heavy oils: A study on the basis of acoustic measurements

The present work propose a methodology combining acoustic, volumetric and calorimetric measurements in order to characterize thermophysical behaviors of heavy oils under conditions similar to those encountered during their production and/or transportation. Ultrasonic velocity measurements were performed in two heavy oils from 283.15 to 373.15 K at pressures up to 20 MPa. Further volumetric measurements, i.e. density, were carried out in the same ranges while heat capacity was determined at the only atmospheric pressure from 300.15 to 373.15 K. Comparisons between direct ultrasonic velocity measurements and calculated speed of sound from its thermodynamic definition which involves both volumetric and calorimetric measurements exhibit a strong divergence below a temperature of 320 K. This difference between the two sets of data means that thermodynamic consistency is not complete, which can mean a singular thermophysical behavior of such fluids.     

Gasification of heavy fuel oils: A thermochemical equilibrium approach

Combustion of heavy fuel oils is a major source of production of particulate emissions and ash, as well as considerable volumes of SO_x and NO_x. Gasification is a technologically advanced and environmentally friendly process of disposing heavy fuel oils by converting them into clean combustible gas products. Thermochemical equilibrium modeling is the basis of an original numerical method implemented in this study to predict the performance of a heavy fuel oil gasifier. The model combines both the chemical and thermodynamic equilibriums of the global gasification reaction in order to predict the final syngas species distribution. Having obtained the composition of the produced syngas, various characteristics of the gasification process can be determined; they include the H₂:CO ratio, process temperature, and heating value of the produced syngas, as well as the cold gas efficiency and carbon conversion efficiency of the process. The influence of the equivalence ratio, oxygen enrichment (the amount of oxygen available in the gasification agent), and pressure on the gasification characteristics is analyzed. The results of simulations are compared with reported experimental measurements through which the numerical model is validated. The detailed investigation performed in the course of this study reveals that the heavy oil gasification is a feasible process that can be utilized to generate a syngas for various industrial applications.     

The study on composition changes of heavy oils during steam stimulation processes

Using the heavy oils obtained from Liaohe oilfields in China, we have conducted the aquathermolysis reaction in laboratory at 240 °C. The results showed that Liaohe heavy oils have been undergoing visbreaking in the process of steam-drive and steam stimulation. After reaction with steam, the viscosity of the heavy oil was reduced by 28-42% and the amount of the saturated and aromatic hydrocarbons increased, while resin and asphaltene decreased. The gas partition chromatography showed that the accumulated amount of carbon numbers increased, after reaction, the accumulated amount of carbon numbers less than C₂₀ are 38.79-53.92%, and before reaction they are 13.30-20.92%. The results provided the basic data for heavy oil recovery by in situ catalytic method in production of heavy oil in oilfields.     

沸腾床渣油加氢技术现状及前景分析

渣油加氢是解决重质劣质原油加工最合理有效的方法,它以其技术成熟、产品收率高、投资回报率高,得到越来越广泛的应用.沸腾床渣油加氢能达到较高的脱杂质率和转化率,并能长周期稳定运转,近年来发展迅速.对其工艺、催化剂和前景等进行介绍和分析,沸腾床渣油加氢符合当前重油深加工的发展需要,能够创造更大的效益.     

A novel model for multi-plant mixed heavy crude oils refinery planning

In this paper, multi-refinery using the same heavy crude oils as raw materials is studied, while a new nonlinear model for mixed heavy crude distillation is proposed. In practical crude distillation operation, the distillate yield and product distribution of distillation units are different due to their various equipment and operating parameters, even the same ratio of raw materials is provided, so different process models for multi-refinery planning is therefore required. For process modeling, the relationships between total yields and mixing ratio of different refineries were determined, which is combined with process simulation using production data. Then, the yields and properties of crude distillation unit (CDU) fractions were calculated with the use of true boiling point (TBP) curves and property curves respectively when the initial cutting temperatures were given. Finally, in order to maximize the economic benefit of distillation, the optimal product distribution and the best mixing ratio of crude oil were calculated under the constraints of different properties of fractions. Comparing to previous models, the proposed model takes the influence of different refinery parameters on production process into account, while avoiding the complex process for determining the cutting points, which is considered more effi-cient and more accurate with respect to heavy crude refinery. Model was successfully verified by a case study, allowing a significant improvement of the refinery profit to be achieved.     

Systematic characterization of petroleum residua based on SFEF

Supercritical fluid extraction and fractionation (SFEF) has been used to separate a variety of petroleum residua and other heavy oils into narrow-cut fractions with total yields up to 75-90%. Any insoluble material, or end-cut, corresponds to the asphaltene fraction in the parent oil. The narrow-cut fractions were analyzed comprehensively and separated into the solubility classes of saturate, aromatic, resin, and asphaltene fractions. The boiling points were measured up to 700 °C and correlations were established with the key factors such as density and molecular weight. This allows extrapolation of boiling points of residue fractions up to 1000 °C. Unlike bulk property measurements, the narrow-cut characterization data show increasing concentrations of key contaminants as the fractions become heavier. The solubility parameter for each narrow-cut fraction was measured using high-pressure fluid phase equilibrium with propane. The corresponding values for the end-cuts were obtained by the conventional precipitation method. The distribution and reactivity of sulfur species were determined by XPS in the bitumen pitch fractions and the corresponding residua produced during thermocracking and hydrocracking. The average structures for the narrow-cuts were constructed from molecular weight and elemental analyses together with FTIR, ¹H-NMR and ¹³C-NMR data. The results were used to develop a generalized feedstock characteristic index, K_R. This index shows good correlation with feedstock hydrocarbon constituents and can be used to assess feedstock reactivity and processability. Downstream refiners can use the narrow-cut data and K_R values for process optimization by either cutting deeper into residua bottoms to increase yield or by selecting the most appropriate process units for the various residue fractions. This information can also be used by upstream operators to determine the economic feasibility of utilizing the end-cut onsite.     

THERMIDOR: A new model for combined simulation of operations and optimization of catalysts in residues hydroprocessing units

Atmospheric or vacuum residues can be upgraded under high hydrogen pressure into valuable distillates and low sulfur fuel oils using several types of hydroprocessing units. Starting from such highly asphaltenic feeds, with the goal to achieve current very low sulfur targets (<0.3%) in fuels for export or subsequent upgrading by catalytic cracking technologies, fixed bed technologies like the HYVAHL process are still the most efficient. This paper discusses some recent developments of HYVAHL, aiming at improved desulfurization levels and operating times. These improvements were helped by the predictions of a newly developed mathematical model called THERmal Monitoring for Isoperformance Desulfurization of Oil Residues (THERMIDOR). This model simulates the HYVAHL process operation along time on stream, taking into account the complex associations of guard bed materials and catalysts including particle size, activity, pore size and shape grading effects. A crucial non trivial achievement in THERMIDOR is the realistic representation of the two main catalyst deactivation mechanisms in residues hydroprocessing: coke and metals deposition. The model shows clearly the synergy between dedicated HDM (“chesnut bur” type, larger mesopores, and macropores) and HDS (higher surface area and activity) catalysts. A very well defined optimum partition of the two catalysts is predicted and found in excellent agreement with the typical optimum determined from pilot plant experiments, and further implemented in commercial plants. The simulation results are successfully compared with representative operational data from a typical HYVAHL plant and reveal new insights on the complex catalyst deactivation phenomena involved in residue hydroprocessing.     

Reburning and burnout simulations of natural gas for heavy oil combustion

Reburning and burnout simulations were carried out through PLUG code of CHEMKIN-III using a reduced mechanism, in order to determine preliminary experimental parameters for achieving maximum NO_x reduction to implement the reburning technology for heavy oil combustion in pilot scale equipments in Brazil. Gas compositions at the entrance of the reburning zone were estimated by the AComb program. Simulations were performed for eight conditions in the usual range of operational parameters for natural gas reburning. The maximum NO reduction (ca. 50%) was reached with 10 and 17.5% of power via natural gas and 1.5 and 3.0% O₂ excess, respectively, at 1273 K. The model predicts 250 ppm of NO, 50 ppm of CO and air mass flows in the range of about 50-130 kg/h for burnout.     

稠油高温相对渗透率实验数据处理方法及软件开发

稠油高温相对渗透率实验数据处理包括水热物性参数计算、实验数据光滑插值、模型求解,这些过程依靠手工计算繁琐,效率低。常规相对渗透率数据处理方法拟合函数单一,适应性差。为此采用了Borland C＋＋编制了稠油蒸汽驱油、湿氮气驱油和热水驱油三种实验条件下的相对渗透率数据处理计算软件,提供了多种数据拟合和处理方法,并且考虑了实验仪器死体积中原油产出非活塞驱、压力滞后、数据波动、数据异常等因素的影响。该软件可以提高高温相渗数据处理的效率和准确性,易于实现数据处理的规范化。     

Catalytic upgrading of biomass-derived oils to transportation fuels and chemicals

This paper provides a review of the catalytic upgrading of biomass-derived oils such as wood pyrolytic oils, plant/vegetable oils and tall oil to transportation fuels and useful chemicals. Both zeolite and hydrotreating type catalysts have been found suitable for upgrading which was usually done in fixed bed reactors. The hydrotreatment of pyrolytic oils at 250-450°C and 15-20 MPa H₂ pressures has been reported to yield up to 55 wt. % of liquid product containing 40-50 wt. % of gasoline range hydrocarbons. In the case of HZSM-5, the upgrading has been carried out at atmospheric pressure and 350-500°C and over 85 wt. % conversions of plant oils and tall oil have been achieved under optimum conditions. Liquid product yields from these oils were up to 70 wt. % of feed which contained 40-50 wt. % aromatic hydrocarbons. With the high pressure pyrolytic oil, pitch conversions of over 75 wt. % have been observed with HZSM-5 using co-feeds such as tetralin. However, there is only scant information available on the kinetic and mechanistic aspects of upgrading of these oils.