Liquefaction of Yallourn brown coal at low pressures and rapid heating rates

Liquefaction of Yallourn brown coal in solvents at high temperature for short contact times and low pressures has been studied. Very high asphaltene yields are achieved with hydrogen-donating solvents (hydrogenated Ashland pitch A240, hydrogenated anthracene oil, and hydrogenated pyrene). For hydrogenated pyrene, yields of almost 90% were obtained during reaction at 450°C for 10 min or at 510°C for 1 min. The average molecular weight of the asphaltene found was 270, with 40 wt% being accounted for by three-and four-ring polynuclear hydrocarbons. The effect of liquefaction temperature, time, and solvents on the asphaltene yield have been examined to clarify the properties required for the solvent under the present conditions used. The behaviour of the asphaltene during pyrolysis and hydrotreatment has also been studied. Some mechanistic aspects of high-temperature, short contact time liquefaction are discussed with regard to the reactivities of the brown coal and the solvents.     

神华上湾煤恒温阶段直接液化反应动力学

为考察神华上湾煤的直接液化性能及反应动力学,以加氢蒽油-洗油混合油作为溶剂、负载型FeOOH作为催化剂,在0.01 t·d^-1煤直接液化连续实验装置上考察了不同反应温度（435~465℃）、不同停留时间（7~110 min）下液化产品组成的演变规律。研究发现,随着煤的裂解及加氢反应的进行,煤及沥青类物质（PAA）收率不断减小,重质液化产物逐步向轻质液化产物转化。当反应温度为455℃、停留时间为90 min时,煤转化率为90.41%（质量分数（,油收率为61.28%（质量分数（。随着反应条件进一步苛刻,油收率下降。基于上湾煤直接液化反应特性及其产物收率变化规律建立了11集总煤直接液化反应动力学候选模型,以BFGS优化算法对实验数据搜索、选优,确定了动力学模型参数。检验结果表明所建立的动力学模型可用于恒温阶段直接液化行为的模拟计算。     

Kinetics of coal liquefaction during heating-up and isothermal stages

Direct liquefaction of Shenhua bituminous coal was carried out in a 500 ml autoclave with iron catalyst and coal liquefaction cycle-oil as solvent at initial hydrogen of 8.0 MPa, residence time of 0–90 min. To investigate the liquefaction kinetics, a model for heating-up and isothermal stages was developed to estimate the rate constants of both stages. In the model, the coal was divided into three parts, easy reactive part, hard reactive part and unreactive part, and four kinetic constants were used to describe the reaction mechanism. The results showed that the model is valid for both heating-up and isothermal stages of liquefaction perfectly. The rate-controlled process for coal liquefaction is the reaction of preasphaltene plus asphaltene (PAA) to oil plus gas (O + G). The upper-limiting conversion of isothermal stage was estimated by the kinetic calculation.     

Study on coal liquefaction characteristics of Chinese coals

The New Energy and Industrial Technology Development Organization (NEDO) has implemented the collaborative research work with China Coal Research Institute (CCRI) on the liquefaction of Chinese coals for about 20 years. A total of 53 runs in a 0.1 t/d bench scale coal liquefaction plant installed at the CCRI were made on 27 kinds of coal selected among coals existing throughout China. The bench plant was operated in a direct hydrogenation (DH) mode and NEDOL mode. In the DH mode, 25 MPa of reaction pressure was employed with decrystallized anthracene oil used as the solvent, while 17 MPa of reaction pressure was employed and hydrogenated solvent was used in the NEDOL mode. This study confirmed that the NEDOL mode, which uses comparatively mild in liquefaction conditions, can liquefy each coal with the high oil yield more efficiently, and is capable of liquefying about 60% of inertinite in high inertinite coals.     

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

The liquefaction kinetics of Powhatan No.5 mine coal (Pittsburgh Seam) in the presence of SRC-II recycle solvent at short contact times (<10 min) and temperature and pressure ranges of 573–723 K and 10.3–13.8 MPa is examined in a well-mixed reactor. In the initial stages of liquefaction, while overall coal conversion (tetrahydrofuran solubles) increases with temperature, oil (pentane solubles) is lost with an increase in temperature. An increase in solvent-to-coal ratio results in an increase of conversion. The initial coal particle size distribution, total pressure, and nature of gas phase (nitrogen or hydrogen) have no significant effect on the production of any of the product of liquefaction for contact times up to 10 min. A lumped kinetic model is presented to describe the product distribution.     

煤直接液化制油技术研究现状及展望

煤直接液化制油技术是促进煤炭清洁高效利用、缓解石油供需矛盾、保障我国能源安全的重要途径。为全面了解煤液化反应机理、动力学、催化剂及工艺的全过程,促进煤直接液化技术基础研究的快速进步和新工艺的开发,笔者综述了国内外在煤加氢液化反应机理、反应动力学、催化剂以及液化工艺方面取得的研究成果,重点介绍了德国IGOR、日本NEDOL和我国的神华煤液化工艺,分析了这些典型煤液化工艺的开发历程和特点;指明了煤直接液化制油技术发展趋势。煤的加氢液化反应是自由基反应机理,是一系列顺序反应和平行反应的综合结果,包含煤的热解、自由基加氢、脱杂原子和缩合反应等,总体上以顺序反应为主。借助同位素示踪、原位实时检测、等离子体技术以及微波快速加热技术等现代分析方法和试验手段,重点研究自由基的产生速率、活性氢产生速率及定量传递机理,有助于深入认识和精准阐明煤加氢液化反应机理。各国学者利用不同的研究方法,针对不同煤种、催化剂、工艺条件和供氢溶剂等,建立了各种各样的动力学模型。动力学模型从单组分到双组分和多组分,从连续反应、平行反应到复杂的网络反应,从最初的一步反应到后来较为合理的多段反应,模型越来越复杂,越来越接近工业应用。根据反应阶段不同进行分段处理的多组分"集总"反应动力学模型将是今后煤加氢液化反应动力学发展的主要方向。借助先进分析手段及科学的处理方法,建立真正揭示不同条件下煤液化动力学规律的通用型动力学模型是未来的发展趋势。借助纳米合成、等离子体等高新技术,调控组分配伍、降低催化剂粒径、优化制备方法是制备高活性催化剂的有效手段。强化系统合理配置和优化集成,重视煤的温和液化和分级转化,优化产品结构,发展直接液化-间接液化耦合技术是煤直接液化未来的发展趋势。     

煤直接液化低分油加氢脱硫脱氮反应动力学研究

为了进一步了解煤直接液化油中硫氮化合物的形态和性质,采用石油研究中的先进分析手段GC-PFPD和GC-NCD,对煤直接液化低分油进行了分析,获得了详细的硫氮化合物组成含量。结果发现:煤直接液化低分油中含有大量的杂环化合物,S主要以苯并噻吩类和二苯并噻吩类化合物存在,N主要以五元环化合物形式存在。在高压釜中进行了催化剂添加量和不同温度条件下的加氢实验,对总硫总氮的加氢反应动力学进行了研究。通过计算得到了高压釜煤液化油加氢脱硫反应的一级反应动力学模型,且通过模型计算的S含量与反应实测的S含量相对误差仅为7.8%;对实验得到的震荡式高压釜中煤液化油加氢脱氮反应的一级反应动力学模型进行验证,发现相对误差也仅为0.97%。     

Petroleum heavy oil mixtures as a source of hydrogen in the liquefaction of Cerrejon coal

Petroleum heavy oil and anthracene oil were used as hydrogen donor solvents in a coal liquefaction test. A positive synergistic effect was obtained when mixed (petroleum heavy oil; anthracene oil) solvent was employed. The temperature of maximum conversion was also lower for this mixed solvent than for any of the solvents alone. It is shown from the ¹ H n.m.r. spectral data that petroleum heavy oil acts as a hydrogen donor to anthracene oil resulting in hydroaromatic derivatives. These hydroaromatic species donate hydrogen to the coal fragments. The ¹ H n.m.r. spectral data allow monitoring of the temperature at which the petroleum heavy oils have maximum donor capacity and consequently the temperature for coal liquefaction in this process.     

神华煤液化反应初期动力学研究

为研究神华煤反应初期动力学行为,在容积180 m L搅拌高压釜中,使用循环溶剂为供氢溶剂,利用"863"催化剂进行煤直接液化反应。采用传统的集总反应动力学模型,将原料煤分为快反应组分,慢反应组分和惰性组分3部分,并计算各级反应动力学活化能。结果表明:快反应煤向油、气和沥青烯组分(PAA)转化的总反应活化能为279.74 k J/mol,慢反应煤向PAA转化的活化能为57.80k J/mol。在开始的4 min内,煤的转化率及PAA的产率由于煤的热解而迅速增加;在后续4~15 min时,转化率增加缓慢,PAA产率基本稳定,并开始降低,表现出了典型的中间产物的特性。当煤的转化率超过55%时,在氢自由基的生成上,溶解氢将发挥重大作用。     

煤直接液化性能的影响因素浅析

发展煤直接液化技术是我国缓解石油供需矛盾和保障能源安全的一个较好的战略选择,但影响煤直接液化性能的因素很多,对这些影响因素进行阐述分析是该技术进一步发展的关键。本文首先在反应原料方面,主要综述了煤的煤化程度、官能团、显微组分和无机矿物质,催化剂的种类、特点、作用、添加量和研究热点,溶剂的种类、作用和研究现状,反应气氛的种类和作用,并指出：煤化程度适中、镜质组含量较高、灰分较低的煤更适宜作为直接液化原料;煤粉担载的原位合成高分散铁基催化剂性能较好,并且经过了工业装置的验证;含有较多部分氢化稠环芳香烃的物料适宜作为煤直接液化溶剂;氢气提供活性氢的机理及其他廉价气体替代氢气气氛还需进一步研究。然后在工艺条件方面,主要分析讨论了反应温度、反应压力、煤浆浓度、进料空速和气液比高低的影响,认为需综合考虑较高的油收率和装置处理量及装置的平稳运行,选择适当的工艺条件。最后指出这些工作将为煤直接液化技术的完善提供一定的参考,我国的煤直接液化产业也将取得良好的发展前景。     

Characteristic diagrams of coal-derived liquids: the correlation between aromaticity and atomic HC ratios

Characteristic diagrams, which are very useful in studies of the reaction pathways in coal liquefaction processes and to characterize coal-derived materials, are presented. Using model compounds, aromatic carbon fraction, f_a, and aromatic proton fraction, f_aH, are plotted against atomic $\text{H}\text{C}$ ratio. The experimental results of an anthracene oil and its hydrogenated oils are plotted on these diagrams, and the usage and the validity of the charts are verified.     

煤间接液化合成油技术研究现状及展望

发展煤炭间接液化技术是缓解我国油品短缺和促进煤炭清洁利用的有效途径。笔者综述了早期经典的费托合成机理如碳化物机理、CO插入机理、中间体缩聚机理,以及近期提出的C2活性物种机理、稀烃再吸附的碳化物理论、网络反应机理等,并指出各机理的合理性和局限性;论述了费托合成反应动力学模型如CO消耗速率动力学模型和详细动力学模型的特点和研究进展。CO消耗动力学模型不考虑碳链增长过程,可很好地预测CO转化率。详细动力学模型含有反应物消耗速率和产物分布信息,其可靠性依据费托合成反应机理。综述了工业上常用的铁基催化剂和钴基催化剂的特点以及在相变、催化机理等方面的研究进展,讨论了新型费托合成催化剂如复合型催化剂、多元金属催化剂和新型载体催化剂的研发进展;介绍了国内外煤间接液化工艺的发展历程,分析了工业化应用中存在的问题和改进方向,重点论述了我国山西煤化所和兖矿集团开发的煤间接液化工艺的特点和工艺流程。最后对未来费托合成反应机理、反应动力学、催化剂及煤间接液化工艺的研究重点和发展方向进行了展望。     

Model for the coal hydrogenation process and its applications

A coal hydrogenation model has been formulated which incorporates both chemical and microscopic experimental data. In this generalized model, carbonization and hydrogenation are viewed as concurrent processes in the liquefaction of coal. Insufficient hydrogen availability, rapid heating rates and long reaction times at elevated temperatures can promote carbonization reactions. The model describes in detail the reaction pathways involved in the hydrogenation of both inertinite and vitrinite. When vitrinite is hydrogenated in the presence of a hydrogen donor solvent, a plastic material called vitroplast is formed. The vitroplast is either converted to liquid and gaseous products when hydrogen availability is high or becomes mesophase and then semicoke when hydrogen availability is low. Even under favourable hydrogenation conditions, the major reaction pathway in the hydrogenation of inertinite is one of initial mild carbonization followed by hydrogenation. It is evident that the difference in hydrogenation behaviour between vitrinite and inertinite is due, in part, to the ability of the hydrogen donor solvent to penetrate vitrinite but not inertinite particles. The hydrogenation model is useful for explaining various phenomena that occur during hydrogenation, such as the formation of mesophase and semicoke, and the blockage of reactors and preheaters.     

胜利褐煤液化初期反应动力学研究

为研究胜利褐煤在初始阶段的煤液化反应动力学,在可快速升降温的微型高压釜中对胜利褐煤进行了加氢液化反应,得到了反应初期煤液化参数,并对胜利褐煤加氢液化反应初期的动力学行为进行分析。结果表明,虽然反应器升温速度较快,但到达反应温度时,仍有一定量的煤发生了转化,在反应温度440℃、反应时间为0时转化率达到28.12%;在较低温度下,胜利褐煤只发生了部分热解反应,反应后期几乎不再转化,在380℃、反应10 min后转化率已达28%,后续基本不变;随着反应温度的升高,反应转化率、油水产率、气产率等指标增大,反应前10 min增速较快,10~25 min时反应速率减缓,主要是沥青烯组分作为中间产物不断向油转化,速率较低。     

Liquefaction of subbituminous coals with a basic nitrogenous model process solvent

Liquefaction reactions in a tubing-bomb reactor have been carried out as a function of coal, coal sampling source, reaction time, atmosphere, temperature, coal pre-treatment, SRC post-treatment and process solvent. Pyridine as well as toluene conversions ranging from 70 to > 90 wt% involving both eastern bituminous and western subbituminous coals are obtained. 1,2,3,4-Tetrahydroquinoline (THQ) has been extensively used as a process solvent under optimized liquefaction conditions of 2:1 solvent: coal, 7.5 MPa H₂, 691 K and 30 min reaction time. Comparisons of THQ with other model process solvents such as methylnaphthalene and tetralin are described. Liquefaction product yield for conversion of subbituminous coal is markedly decreased when surface water is removed from the coal by drying in vacuo at room temperature prior to liquefaction. The effect of mixing THQ with Wilsonville hydrogenated process solvent in the liquefaction of Wyodak and Indiana V coals is described.     

蒽油加氢转化为轻质燃料油技术研究

综述了煤焦油加氢技术的现状,通过原料分析确定了蒽油加氢的工艺路线。对加氢精制催化剂和加氢改质催化剂进行了选择确定,并考察了反应温度对加氢精制产物的影响及对改质效果的影响,确定了其工艺条件。经此过程,使约97%的蒽油转化为清洁燃料油,其中石脑油馏分收率3.9%,柴油馏分收率93.0%,十六烷值为37.0,加氢改质后质量较仅加氢精制柴油馏分得到大幅提高。     

Evidence for trace element forms of titanium and manganese in coal liquefaction extract solutions

The trace element contents of the insoluble portions of a filtered coal extract solution treated with pentane, toluene and THF were determined using atomic absorption spectroscopy (a.a.s.) and atomic emission spectroscopy (a.e.s.). In all cases a large proportion of the trace elements were found in the insoluble portion, but there were no significant differences between the individual trace elements. Further experiments were carried out in which TiO₂, MnCO₃ and low temperature ash were added to normal digestions of coal in hydrogenated anthracene oil (HAO), and were also digested in HAO only. The filter cakes produced in the latter experiments were redigested in fresh HAO a second and third time. The results strongly indicate that Ti passes through the filtration stage of the liquefaction process as finely-divided mineral matter. Mn, however, undergoes some change during the process which enables it to pass through the filtration stage.     

Approach for promoting liquid yield in direct liquefaction of Shenhua coal

Single and multi-stage liquefaction of Shenhua (SH) bituminous coal and re-liquefaction of its liquefaction residue (SHLR) were carried out in an autoclave reactor to investigate the essential approach for promoting oil yield and conversion in SH coal direct liquefaction (SHDL). The multi-stage liquefaction includes pretreatment, keeping the reactor at 250 °C for 40 min before heating up to the reaction temperature, and two-stage liquefaction processes consisting of low temperature stage, 400 °C, and high temperature stage, 460 °C. The results show that the pretreatment has slight effect on oil yield and conversion of SHDL, especially for liquefaction at 460 °C. There is a positive function of two-stage liquefaction in shortening reaction time at high temperature. Increasing ratio of solvent to SHLR can promote the oil yield and abate reaction condition in SHLR re-liquefaction, that is, it can promote the conversion from preasphaltene and asphaltene to oil. The primary factor to inhibit coal liquefaction is the consumption of hydrogen free radical (H·) from solvent or H₂ and condensation of free radicals from coal pyrolysis after a period of reaction. So the essential approach for increasing oil yield and conversion of SHDL is to provide enough H· to stabilize the free radicals from coal pyrolysis.     

The quantitative analysis of coal processing solvents by combined g.c.-m.s.

The application of combined g.c.-m.s. with automated data processing to the rapid analysis of coal solvents has been described. An analytical method, using commercially available data processing routines, has been developed for the automatic quantitative analysis of specific aromatic and hydroaromatic compounds in coal processing solvents. To demonstrate the use of this technique, raw anthracene oil was hydrogenated under different conditions and the resulting hydrogenated anthracene oils were analysed. The results showed correlations between the hydrogen content and the absolute concentrations of specific compounds in the samples.     

WTW车用煤基燃料的经济性与环保性研究

为了研究WTW车用燃料的经济性与环保性,利用GREET模型对煤间接液化合成油、煤直接液化合成油、煤制天然气和整体煤气化联合循环发电IGCC 4种煤基燃料进行WTW计算,并对比分析了4种燃料在WTW各个阶段的能耗和CO2排放量。结果表明：4种煤基燃料的能耗由大到小为煤制天然气〉煤间接液化合成油〉煤直接液化合成油〉IGCC,其中煤间接液化合成油、煤直接液化合成油及煤制天然气的能耗都约为传统柴油或汽油的2倍,IGCC的总能耗是传统汽油的3/5左右;CO2排放排序为：煤间接液化合成油〉煤制天然气〉煤直接液化合成油〉IGCC,其中煤间接液化合成油、煤直接液化合成油和煤制天然气的CO2排放量都为传统柴油或汽油的1.6～3.1倍,IGCC的CO2排放量是传统汽油的7/10左右;煤间接、直接液化合成油和煤制天然气都有一定的市场竞争力,IGCC成本较高,且高于传统发电成本。