中国直接液化油煤浆及液化残渣流变特性研究进展

在煤直接液化工艺中,油煤浆和液化残渣的流变特性参数是工艺设计的重要基础数据之一。本文总结了我国液化油煤浆在常压常温、常压升温和加压升温条件下流变特性的研究进展和相应的流变模型,介绍了溶剂的性质、煤在溶剂中的溶胀、煤的热溶产物或初始液化反应产物等对煤浆体系黏度变化的影响,对开展我国液化油煤浆和液化残渣的流变特性研究,具有一定的指导意义。     

油煤浆黏温特性研究进展

煤直接液化技术是缓解石油供需矛盾、实现煤炭清洁高效利用的重要技术途径之一,油煤浆的黏温特性对其配制、输送、加压、预热及反应性能具有重要影响。本文从油煤浆黏温特性的变化规律、研究方法、变化机理、影响因素等方面的研究进展进行了综述。在升温过程中,油煤浆流变特性表现为非牛顿流体,具有剪切稀化特性;高温高压下黏度测定方法主要有4种;分析黏温特性变化机理：煤浆制备和升温阶段黏度变化主要由溶胀作用导致,高温阶段主要由煤裂解产生沥青质（尤其是前沥青烯）导致;从溶剂、煤的性质（煤阶、显微组分及粒径分布）、剪切速率、油煤浆浓度、催化剂和氢分压等方面分析了油煤浆黏温特性的影响因素。最后指出了未来油煤浆黏温特性的研究方向,为我国煤直接液化技术的进一步发展提供参考。     

分级研磨工艺制高浓度油煤浆的试验研究

以内蒙古吉林郭勒地区的褐煤为试验原料,分别采用直接液化常规的油煤浆制备工艺和分级研磨制浆工艺进行成浆性试验,并对试验得到的油煤浆的粘温特性进行对比研究。结果表明：与常规制浆工艺相比,分级研磨制浆工艺可使油煤浆浓度提高4%,且煤浆的流变性和稳定性均有明显改善;油煤浆的粘度随温度的升高呈现出先降低后升高的趋势,分级研磨工艺制得的油煤浆发生明显溶胀作用的温度较常规工艺高20℃。     

油煤浆中溶剂的黏度与油煤浆黏度关系的研究

安庆芳烃萃取油是理想的煤液化起始溶剂的原料,常压,100℃以下用德国Haake旋转黏度仪测定了不同加氢次数安庆芳烃萃取油的黏度,神华煤液化循环溶剂的黏度及其相对应的干煤浓度为45%的煤浆黏度变化,提供了油煤浆中溶剂的黏度与油煤浆黏度关系的一种方法。     

煤直接液化中煤浆黏度变化研究进展

在煤直接液化中,煤浆黏度变化是一个十分重要的工艺性问题,至今尚未得到充分研究．在升温过程中,由于煤与循环油之间的相互作用,煤浆黏度会发生明显变化,甚至出现一至两次突变．对煤浆在高温高压下黏度变化研究方法,各种因素如温度、煤阶、催化剂、剪切速率和油煤比等的影响及有关机理以及预测黏度变化的模型等作了概述和讨论,对进一步开展这一方面的研究和煤直接液化技术的工业开发有一定参考价值．     

新疆黑山煤直接液化性能研究

神华集团有限责任公司为实施新疆煤炭转化战略,对位于新疆自治区吐鲁番州托克逊县的黑山煤进行了煤直接加氢液化研究,分别在0.5 L的高压釜和0.12 t/d的连续装置上进行了直接液化实验.结果表明,黑山煤具有良好的液化性能和优异的成浆性能,在可输送的黏度范围内可制得浓度高达50%的油煤浆,且能长周期稳定运转并取得较高的油收率和较低的气产率.高浓度煤浆的稳定输送特性可大大提高煤液化反应器的处理能力.     

煤直接液化工艺中煤浆黏温特性变化机理的研究进展

煤直接液化过程中煤浆黏度的变化严重影响设备的正常运行,油煤浆的黏温特性是煤直接液化工艺设计与开发的重要参数。对国外直接液化条件下油煤浆黏温性能变化机理的研究进行了综述,介绍了溶胀作用及沥青烯、前沥青烯等煤衍生物的非共价键作用等多种形成机理,并对进一步深入研究提出了几点看法。     

煤浆性能及其稳定性影响因素研究述评

论述了在煤直接液化过程中，煤、溶剂、催化剂、温度、压力以及混合方式等因素对煤浆性能的影响规律．并对进一步深入研究提出了几点建议。     

重质油组成与结构对油煤浆流变性能的影响

新疆低阶煤和重质油资源丰富,具有广阔的煤油共液化工业前景,但重质油自身流动性差,极大地限制了煤油共液化的发展。为认识重质油组成结构对油煤浆流变性能的影响,选取5种性质差异明显的重质油和2种工业循环溶剂油,探究其与上湾煤形成的油煤浆流变性能变化规律,在此基础上通过预加氢调控减压渣油的组成结构,分析重质油组成、结构与流变性能,获得重质油组成结构对油煤浆流变性能的影响规律。结果表明,重质油本身是牛顿流体,加入煤粉后转变为假塑性流体,呈现剪切稀化特征;重质油中胶质和沥青质组分含量越高,形成油煤浆的黏度越高,体系内部的触变结构越丰富,非牛顿流体特征越明显。减压渣油稠油预加氢后,形成油煤浆的黏度显著降低,其中,380℃下预加氢2 h后制成的油煤浆黏度在135℃时降至451 mPa·s,同时油煤浆的触变特性也明显减弱。预加氢促使减压渣油中的长链断裂为短链烃,胶质和沥青质组分转化为饱和分与芳香分,从而抑制胶团的生成,降低油煤浆黏度。其中,380℃下预加氢2 h后胶质含量较未处理减少约21%,重均分子量降至1 594 Da,芳香环β位的H含量增加约20%。     

中温煤焦油与新疆黑山煤共处理的研究

在0.5L搅拌式高压釜上开展了中温煤焦油与新疆黑山煤共处理的实验研究,考察了中温煤焦油添加量对新疆黑山煤制浆性能和液化结果的影响,探索中温煤焦油加工利用新途径.结果表明,添加中温煤焦油增加了油煤浆输送时的黏度,在油煤浆浓度为42%时,中温煤焦油添加量不高于18%.与新疆黑山煤单独液化相比,中温煤焦油与新疆黑山煤共处理具有氢耗、气产率、转化率和油产率高的特点;添加适量的中温煤焦油对新疆黑山煤液化具有正协同效应,添加量大于20%时反而对煤转化不利;最佳添加量为5%,与煤单独处理的结果相比,转化率高1.6%,油产率高1.1%;添加量大于20%时,油收率下降.因此,添加适量的中温煤焦油与新疆黑山煤共处理,既可提高煤的转化率和油收率,又可加工利用中温煤焦油,提高煤直接液化的经济效益.     

油煤浆表观黏度测定方法研究

为建立油煤浆表观黏度测定标准,实现油煤浆表观黏度的准确测量,研究了多种煤液化油煤浆在不同条件下的流变行为,考察了剪切速率、测量温度、样品放置时间、读数开始时间等因素对油煤浆表观黏度测值的影响,并确定了油煤浆表观黏度测定方法的精密度。结果表明:测定油煤浆表观黏度的最佳条件为:剪切速率100 s-1,测量温度60℃,油煤浆取样后应立即进行黏度测定,启动旋转黏度计后,第11 min开始记录读数,每隔10 s记录一次,共计30次,以测定结果的平均值为样品黏度值,修约到整数位报出。规定油煤浆表观黏度测定方法的重复性限r=0.13η100 s-1-4.30,由于试验仪器条件的限制,未对再现性做出说明。     

煤直接液化条件下神华煤煤浆粘度的测定

为研究煤直接液化条件下煤浆的粘度变化,利用剪应力分解法测量了神华煤煤浆在250～450℃的温度范围内的粘度,发现在340℃以前粘度总体呈下降趋势,340℃以后粘度开始上升,并在380℃出现峰值,而后粘度又逐渐下降。对升温速率的影响做了简单分析,发现升温速率变大,出现粘度峰的温度增高。     

Moisture readsorption and low temperature oxidation characteristics of upgraded low rank coal

This study investigated the behavior of upgraded low rank coal produced by a coal-oil slurry dewatering process regarding moisture readsorption, low temperature oxidation, and spontaneous combustion. The upgraded low rank coal had higher heating values than raw coal. It also showed lower moisture readsorption than raw coal and had less susceptibility to low temperature oxidation and spontaneous combustion. This seemed to result from the coating of the asphalt on the surface of the coal, which covered fine pores and suppressed the active functional groups from reacting with moisture and oxygen in the air. The increasing upgrading pressure negatively affected the moisture readsorption, low temperature oxidation, and spontaneous combustion.     

Flotation of Fine Gold Particles by the Assistance of Coal-Oil Agglomerates

This paper describes the use of coal-oil agglomerates in flotation to increase the gold recovery from an ore containing fine gold particles. The effects of operating parameters on gold flotation recovery such as oil type, particle size of agglomerating material, agglomerate/ore and oil/ore ratios were investigated. The studies showed that petroleum oils are more effective than vegetable oils in oil agglomeration of Kozlu coal and coal-oil assisted gold flotation. Gold recovery can be increased using a higher amount of agglomerates in the process; however, gold grade of the flotation concentrates is reduced significantly. The use of bridging oil at high concentrations in the agglomeration process provides high-grade gold concentrates, but lower recoveries. The utilization of coarser coal particles in the coal-oil agglomeration stage leads to higher selectivity and recovery values for gold particles.     

油煤浆输送管道弯管部位流场的数值模拟与磨损预测

针对煤液化工业中油煤浆管道,利用fluent软件对7种不同管径,8种弯径比的弯管部位的流场进行了模拟计算,得到在湍流状态下管内速度场分布。通过二次开发将磨损模型嵌入到Fluent软件中,实现了对弯管部位的磨损预测。数值计算结果表明,弯径比不同,弯管的磨损区域与磨损量有较大差异;同一管径时,随着弯径比增大,最大磨损量减小。考虑到管路经济性,弯径比取4—6是比较适宜的。     

Grinding of coal-oil slurries with the szego mill

Grinding of coal in fuel oil for coal-oil mixtures (COM) preparation is simpler and may give better slurry properties than dry grinding followed by dispersion in oil. A 42 weight percent slurry of 600–840 μm particles of Pittsburgh coal in #2, #4, and #6 fuel oils has been ground with the novel Szego mill. Particle size distributions at different residence times are reported down to a 10 μm median size, together with energy consumption data. Low mill hold-ups and high rotational speeds enhanced the rate of grinding.     

Single droplet combustion of coal-oil/methanol/water mixtures

Single droplet combustion of coal-oil/methanol/water mixtures was investigated. A microexplosion occured during the gas-phase combustion period of emulsified fuels and caused secondary atomization of fuel droplets. The microexplosion during the combustion of a coal-oil/methanol/water mixture was the most violent of all the sample fuels and its apparent overall burning rate coefficient was maintained at the highest value over the range of ambient air temperatures used, 850–1000 °C. It was concluded that an appropriate addition of water and/or methanol could improve the combustion characteristics of coal/oil mixtures. The apparent overall burning rate coefficient of a methanol/coal/oil mixture was 2–3 times higher than that of a coal/oil mixture. However, that of a water/coal/oil mixture was 2–10 times higher than that of a coal/oil mixture.     

粉体粒度对神府煤制备高性能水煤浆的影响

神府煤内水含量高、氧碳比高,不利于湿法气化制备高性能水煤浆。选择神府同一矿区的原煤、洗煤,通过干磨湿配制浆,并对煤浆性能进行分析。结果表明,煤的可磨指数HGI与磨矿时间共同决定粉体的粒度分布,粉体粒度与煤浆的流动性及稳定性直接相关,磨矿过程应尽可能使粉体粒度偏细。粒度〉0.20 mm的粉体主要影响煤浆的稳定性,较多的大颗粒会因重力沉降作用导致煤浆性能变差;粒度〈0.076 mm的粉体主要影响煤浆的流动性,合适的质量比配能与大颗粒形成双级或多级级配。SFR、SFX制浆性能较好时粒度〈0.076 mm的粉体分别占45%、50%。     

Characterization of coal—oil mixtures by a pseudo diffusivity parameter

For the use of coal—oil mixtures as combustion fuels stable maintenance of the solid—liquid suspension is vital and for this reason the settling properties of these mixtures were studied with a system of ultrasonic sensors. The sedimentation theory of Smiles, which relies on unsteady state diffusion analogies, was applied successfully to the coal-oil mixtures and pseudo diffusion coefficients were determined.