离子液体[BMIm]BF_4在神华煤溶胀预处理中的应用

采用离子液体1-丁基-3-甲基咪唑四氟硼酸盐([BMIm]BF4)对中国神华煤进行直接液化前的溶胀处理,通过对溶胀度的测定及不同条件下溶胀煤样的直接液化实验,探讨了离子液体[BMIm]BF4在煤溶胀预处理方面的应用.结果表明,离子液体[BMIm]BF4溶胀预处理能破坏煤结构中的弱共价键,使煤的溶胀度获得了显著提高,进而改善了其液化性能,提高了煤的直接液化转化率和油气产率.在溶胀条件方面,随溶胀时间的增加,煤溶胀度和液化转化率提高;而温度对煤溶胀度和液化转化率的影响较复杂,存在一个合适的溶胀温度范围,在此温度之上,溶胀度和液化转化率随温度的升高而降低.而且使用过的[BMIm]BF4可以回收循环使用.     

吡啶与[BMIm]BF_4在煤液化预处理中的应用研究

分别采用吡啶、离子液体1-丁基-3-甲基咪唑四氟硼酸盐([BMIm]BF4)对原煤进行溶胀预处理,在不同溶胀温度和溶胀时间下,试验测试了两种溶剂对溶胀度、抽提率及溶胀煤直接液化等情况,结果表明,[BMIm]BF4在煤炭液化预处理过程中可代替原有溶胀剂吡啶。     

超声波辐射溶胀对煤炭直接液化性能的影响

为探讨超声波辐射溶胀在煤炭直接液化过程中的积极作用,以吡啶为溶胀剂对神华煤进行了超声波辐射条件下的溶剂溶胀处理,通过对溶胀过程中不同溶胀时间煤样的溶胀度与质量损失情况测定以及超声波辐射溶胀煤与自然溶胀煤的液化实验比较,发现超声辐射有助于煤的溶胀作用,煤液化转化率提高了3%~4%.实验表明,超声溶胀能够进一步提高煤催化加氢直接液化的反应性能.     

溶胀对扎赉诺尔褐煤热解及液化性能的影响

研究了用吡啶和四氢呋喃（ＴＨＦ）溶剂对扎赉诺尔褐煤（ＺＬ）溶胀预处理后煤的热重、微分热重的变化及加氢液化反应规律。结果表明：煤经吡啶和ＴＨＦ溶胀预处理后增加了煤的热解失重量及加氢液化反应性,提高了煤的液化总转化率和油气产率;其中吡啶预处理煤的热失重率和液化转化率高于ＴＨＦ预处理煤。用经外光谱对溶胀煤的分析表明,煤溶胀预处理后其大分子结构中氢键发生不同程度的断裂。     

煤溶胀前后溶解度参数变化研究

选择6种性质不同的溶剂作为溶胀剂,对烟煤进行了溶胀预处理。对溶胀前后煤样进行了形貌分析、红外分析及溶解度参数测定,并考察了直接加氢液化效果。结果表明,溶剂溶胀预处理未破坏煤大分子结构,而煤的微观形貌变得疏松。所选6种溶剂中,N,N-二甲基甲酰胺(DMF)与煤二者之间的溶解度参数差值最小,DMF对煤溶胀效果也最好,溶胀度达1.71。同时,6种溶胀煤中,经DMF溶胀煤样(C_(DMF))的溶解度参数值最低,直接液化性能最好。相比于原煤(C_R),C_(DMF)的溶解度参数降低了2.73%,气产率降低了89.71%,液产率和转化率分别提高了27.48%和5.35%。     

神华煤直接液化性能及固体酸催化可行性研究

利用微型压热釜考察了气氛、温度、氢气初压及煤溶剂比等工艺条件对神华煤直接液化转化率和产物分布的影响，结合神华煤的溶剂抽提性能和产物表征，系统地研究了神华煤加氢液化性能，并通过与FeS和FeS＋S等催化剂对比实验，初步探讨了SO2^2-／MxOy型固体酸催化煤加氢液化的可行性．结果表明，神华煤中以非共价键作用结合的小分子化合物含量较低，煤中的羟基主要位于大分子骨架结构中；神华煤具有良好的液化性能，400℃，煤／四氢萘比为1：2，SO4^2-／ZrO2为催化剂时最高转化率达到76．3％，气氛、初压、液化温度及煤溶剂比对液化转化率具有较大影响，较高温度及强的供氢体系有利于提高煤的转化率及油气产率．三种催化剂的催化活性顺序为：FeS〈FeS＋S〈SO4^2-／ZrO2，其中SO4^2-／ZrO2固体酸不仅具有良好的液化转化率，而且油气收率高，值得进一步研究开发．     

循环供氢溶剂在神华煤直接液化工艺中的应用

在神华煤直接液化工艺中,为达到理想的反应深度,煤直接液化反应需要供氢性能良好的循环供氢溶剂、氢气、煤粉及催化剂等原料。其中,经过预加氢处理后的循环溶剂,具有良好的供氢性能,使得煤直接液化反应条件温和。在煤直接液化过程中,溶剂起着溶解煤粒、溶胀分散、稳定自由基、提供和传递转移活性氢、稀释液化产物等作用。当前,提高循环供氢溶剂自身的供氢和传递氢能力是煤直接液化新技术开发的重点之一。     

煤的结构对直接液化反应性影响的分析

系统地分析了煤的组成结构及液化前的预处理对直接液化反应性的影响，包括煤阶、岩相组成、各种矿物质及酸洗脱除、水分及烘干、孔隙性、物理结构及预溶胀、H／C比等，指出不同的工艺条件下它们对直接液化的影响是不同的。     

煤溶胀影响因素及溶胀技术的应用

以煤溶胀机理、溶胀动力学等为基础,综述了溶剂性质、煤阶、氧化、温度、预处理、溶胀时间、水分、煤粉粒度等对煤溶胀的影响。结果发现:溶剂的供电子数目(EDN)、溶剂碱性、溶剂类型对煤的溶胀有不同的影响。煤阶对煤的溶胀影响较大,表现在随着C的增多,溶胀度也在增大,但当C含量大于85%时,溶胀度急剧降低。氧化煤易于溶胀。升高温度和预处理均有利于煤的溶胀。煤粉粒度越小溶胀度越好。脱除煤中的矿物质后有利于提高煤的溶胀度,但增加幅度不大。最后详细介绍了煤溶胀技术在研究煤分子结构、煤热解、煤液化方面的应用。     

几种煤的溶胀动力学研究

测定了不同溶胀时间下胜利煤、H煤和神华煤在九江循环溶剂中的的溶胀度,研究了这三种煤在常压下溶胀动力学行为,胜利煤、神华煤和H煤的平衡溶胀度(溶胀4 h)分别为1.068,1.054和1.162,胜利煤和神华煤约35 min达到溶胀平衡,H煤约20 min即达到溶胀平衡,开发了一种新的溶胀动力学模型--吸附溶胀动力学模型,按二级动力学方程对煤粒的溶胀行为进行描述,并利用文献查得的Suuberg法动力学方程分析可知,胜利煤、H煤和神华煤在九江溶剂中的扩散主要是Case-Ⅱ扩散,经比较可知,吸附溶胀法较Suuberg法能更好地描述煤的溶胀行为.     

Effect of pre-swelling of coal on its solvent extraction and liquefaction properties

Effects of pre-swelling of coal on solvent extraction and liquefaction properties were studied with Shenhua coal. It was found that pre-swelling treatments of the coal in three solvents, i.e., toluene (TOL), N-methyl-2-pyrrolidinone (NMP) and tetralin (THN) increased its extraction yield and liquefaction conversion, and differed the liquefied product distributions. The pre-swollen coals after removing the swelling solvents showed increased conversion in liquefaction compared with that of the swollen coals in the presence of swelling solvents. It was also found that the yields of (oil + gas) in liquefaction of the pre-swollen coals with NMP and TOL dramatically decreased in the presence of swelling solvent. TG and FTIR analyses of the raw coal, the swollen coals and the liquefied products were carried out in order to investigate the mechanism governing the effects of pre-swelling treatment on coal extraction and liquefaction. The results showed that the swelling pre-treatment could disrupt some non-covalent interactions of the coal molecules, relax its network structure and loosened the coal structure. It would thus benefit diffusion of a hydrogen donor solvent into the coal structure during liquefaction, and also enhance the hydrogen donating ability of the hydrogen-rich species derived from the coal.     

Effects of solvent pretreatment and solvent incorporation on coal liquefaction

Yields of short-contact-time liquefaction product can be increased by pretreating the coal-solvent slurry at below normal liquefaction temperatures to permit solvent incorporation and/or swelling of the coal before liquefaction. An external pretreatment and an in situ pretreatment produce similar results. A coal-vehicle adduct was isolated from the pretreated coal and had liquefaction characteristics similar to the original coal. The beneficial effect of the solvent pretreatment is therefore believed to be the result of physical solvent incorporation with the coal, which causes solvent-aided liquefaction, in contrast with the thermal decomposition that can occur if some of the coal reaches liquefaction temperatures before it is contacted by vehicle. Pretreatment allows vehicle to be present (in contact with coal) at the reactive site in order to react with, and cap, coal free radicals.     

冷冻预处理对神府长焰煤萃取率的影响及机理研究

以神府长焰煤为研究对象,对其进行冷冻预处理,然后利用四氢呋喃对煤样进行索氏萃取,研究冷冻预处理的温度和时间对煤样萃取率的影响规律,获得冷冻预处理提高煤样萃取率的最优实验条件。通过分析冷冻预处理前后煤样的孔结构、表面形貌、萃取物的红外光谱和X射线光电子能谱,提出冷冻预处理提高煤样萃取率的机理。结果表明:冷冻预处理提高了煤样的萃取率,最优实验条件为温度-80℃、时间12h;在最优实验条件下,煤样的四氢呋喃萃取率由6.16%增加到7.67%,增加了24.68%;孔结构分析结果表明,与原煤相比,冷冻预处理后煤样的孔容、孔径和比表面积均增加,其中比表面积由6.77m²/g增加至7.21m²/g,增加了6.50%,孔容由0.011 mL/g增加至0.013mL/g,增加了18.18%,孔径由7.30nm增加到7.32nm,增加了0.27%;扫描电镜实验结果表明,与原煤相比,冷冻预处理后样品的表面粗糙度增加;红外光谱及X射线光电子能谱分析结果表明,冷冻预处理增加了萃取物中脂肪烃的含量,含C=C,C=O及C—O键的化合物含量减少。冷冻预处理提高煤样萃取率的机理为:冷冻预处理增大了煤样的孔容,对其进行溶剂萃取,有利于大分子骨架缝隙中独立存在的脂肪族低分子化合物的溶出。     

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。     

Separation of Solids from Coal Liquefaction Products via Countercurrent Solvent Deasphalting

Abstract

Counter-current deasphalting is a key unit operation in the Dow Liquefaction Process. The Dow developed deasphalter removes typically 99.8–99.9% of the ash and 94–95% of the toluene insoluble hydrocarbons from the coal liquefaction product.

The deasphalted oil, after separation from solvent, contains less than 0.05% ash. Deasphalted coal liquefaction product, a low sulfur, low residue, premium synthetic oil, constitutes 40% of the net liquefaction products. The deasphalter residue typically contains 40% ash and up to 25% hydrocarbonaceous coal solids. It has a heating value of approximately 9000 BTU/1b and is produced as a viscous pumpable fluid. These properties are important in the Dow Process where deasphalter residue is gasified to generate the hydrogen for the liquefaction step. The solvent used in the deasphalter is a paraffinic 50–75° light oil cut from the liquefaction unit.

The counter-current deasphalting technology is based on the results from model and batch studies and results from the operation of two different 23 kg/hr continuous deasphalters. Operational parameters which have been studied include: extraction temperature and pressure, solvent to oil ratio, feedrate, coal oil composition and variations in column design.

The mass transfer which occurs during the deasphalting of coal liquefaction product is accompanied by interfacial tension gradients which develop naturally during the extraction process. The resulting interfacial convection (referred to as a Marangoni instability) profoundly enhances the rate of the extraction process and greatly simplifies the design of the extraction column.     

低阶煤预处理技术的研究进展

简述了低阶煤的利用现状及热转换过程中存在的问题,总结了水热预处理、酸预处理、溶剂溶胀、热预处理、氧烷基化及加氢预处理等预处理技术对低阶煤的结构、热解反应性和焦油品质及收率的影响。提出了合适的预处理技术可以降低煤的液化条件,提高煤的热转换效率,改善焦油品质,实现低阶煤的清洁高效利用。     

溶胀煤制备及煤加氢液化性能的研究

在自然和微波条件下,对五彩湾煤进行溶胀处理,进行煤质、电镜、热解、煤的结构-化学指数分类、加氢液化产率和液化残渣热解的分析。实验结果表明:五彩湾煤自然溶胀煤样和微波溶胀煤样的层状和裂纹显著增加,失重量明显增大。煤加氢液化测试结果表明,在氢初压6.0 MPa、溶煤比1.75:1、反应温度450℃和反应时间60 min条件下,气产率由原煤的9.7%,降低到两种溶胀煤均在3.4%左右;油产率由原煤的55.2%,提高到自然溶胀煤的70.1%和微波溶胀煤的74.0%;转化率由原煤的76.8%,增加到自然溶胀煤的82.1%和微波溶胀煤的84.8%。可见,经过溶胀处理,煤加氢液化效果显著。     

常压低温条件下油煤浆黏度变化的研究

在煤直接液化过程中，油煤浆的黏度变化是工艺设计的重要参数之一．进行了常压低温条件下影响油煤浆黏度变化的实验研究，分析了溶剂、煤粒度、煤油比以及外力因素如剪切速率、温度和溶胀等条件对煤浆黏度的影响规律．实验结果表明：煤浆的黏度随溶剂黏度的增大而增大，随煤颗粒粒度增大而减小，随煤油比增大而升高．煤浆的表观黏度随剪切速率的增大而逐渐降低，表现出一定的剪切稀化性，煤颗粒在溶剂中发生溶胀，煤浆体系的黏度由于溶胀而增大．温度对浆体的黏度影响较大，黏度随温度升高而降低，通过对实验数据的数学回归，建立了一定温度范围内黏度随温度变化的定量关系式．