影响煤样准确制备的因素分析

从制样人员、制样设备、制样设施环境、制样缩分方法选择以及样品均匀程度等方面分析了影响煤样准确制备的因素,并提出了相应解决的途径和方法。     

影响煤粘结指数测定准确性的因素

为了提高煤粘结指数测定的准确度,本文考察了制样时间、制样粒度、焦化温度、焦化时间、灰分、样品制备后保留时间等因素影响。探讨了不同试验条件下同一煤样粘结指数测定结果的差异。试验结果表明,以上各因素在不同条件下对测定结果的准确性影响较大。     

适用于煤矿井下加砂压裂的压裂液性能研究

目前煤矿普遍采取井下清水压裂后抽排瓦斯,但是压后裂缝难免重新闭合,为了提高瓦斯抽排效果,采用加砂压裂。优选适用于煤矿井下加砂压裂的清洁压裂液,评价其携砂、防膨、破胶与伤害性能力等。该压裂液体系煤心伤害率为19.62%,支撑剂在压裂液中基本不沉降,表现出优异的高携砂、低伤害性能,适用于低排量、高砂比的煤矿井下加砂压裂施工。     

煤炭采制样常见问题分析及对策

煤炭采制样过程中常见问题主要有对采制样岗位的重视程度低,未按标准采制样,人工采制样工具及设备规格不统一,机械化采制样有混样现象等。针对上述问题,从采样和制样两方面提出了相应的对策。煤堆采样的子样点应按煤堆顶、腰、底分布,一般可按1∶3∶5的比例布点;火车顶部和汽车采样时,尽量采用机械化采样,按照"均匀布点,使每一部分煤均有机会被采出"的原则布置子样点;煤流采样时一般根据煤流量大小,以1次或分2～3次横截煤流断面采取一个子样,输送带采样应尽可能安装输送带机械化采样器。制备分析煤样时,对全水分超过10%以上的煤样,要进行初干燥;制备全水分煤样时首选水分损失最小的方法;制好的煤样应装入密闭玻璃瓶保存。加强采制化管理,规范采制样操作对于提高煤质分析准确性,保障优质原料煤供应具有重要意义。     

氢氧化钠水解小麦秸秆制备型煤黏结剂的研究

为改善型煤燃烧性能,提高农作物小麦秸秆利用率,用NaOH降解的小麦秸秆制备了生物质型煤黏结剂。通过正交实验,制备不同实验条件下的型煤黏结剂,并测定所制型煤的抗压强度,得到型煤黏结剂的最佳制备条件:固水比1∶30,Na OH质量分数为4%,反应温度为90℃,恒温水浴中加热4 h,固硫剂添加量为1.0 g。在此条件下制备的黏结剂中添加质量分数2%聚乙烯醇,经过型煤抗压强度测试,结果显示:添加聚乙烯醇后,黏结剂抗压强度提高;所制型煤的灰分7.1%～8.4%,挥发分27.1%～28.4%,黏结指数10.835～11.796,弹筒发热量28.453 MJ/kg～30.589 MJ/kg。     

陕北洁净型煤的煤岩配煤方法研究

为了合理利用陕北当地煤炭资源生产优质型煤,通过煤岩配煤方法,将实验煤样的镜质组反射率分布通过方程转换成类强度指数PSI集合,以标准型煤的PSI为目标求解参配煤的比例,采用MATLAB进行多元线性规划的矩阵计算。利用解多元线性规划的限制条件(归一化、加入煤泥、某个特定的原料含量等)可使所配的洁净型煤满足指标要求。结果表明:在特定的标准下,有的待配煤不适合参与配煤,需要剔除;按归一化原则得到的合成型煤与标准型煤的煤岩指标吻合度较无归一化原则时高;该方法可以实现在指定某种原料及含量时配煤;配煤计算完成后,还可以检验可加和的指标是否满足工业指标要求。     

文摘

型煤技术的新进展Уголвукраны,(8),44(1988) 本文介绍了用德聂伯罗夫斯克煤田的煤制型煤的质量改进工作。用粒径为0～1毫米和3～6毫米的褐煤制型煤时,最佳水份分别为13～14%和26～27%,挤压压力约为100MPa。针对用黑煤和褐煤制型煤进行了研究开发工作。与褐煤制得的型煤相比,用于褐煤、气煤粉和粘结剂混合制得的型煤各种参数较高:热值高30～35%,机械强度高     

浅谈制样过程对烟煤黏结指数的影响

黏结指数是反映烟煤黏结性的重要指标,为了准确测定黏结指数,通过对比试验,从煤的制样和干燥两方面讨论了不同操作方法对黏结指数测定的影响。结果表明,应尽量采用手工的方法或机械多次研磨的方法来制备测定黏结指数所需的煤样,而且样品的干燥不宜在超过规定温度的环境下进行,必须采用标准方式干燥。     

陕北高硫煤筛分浮沉脱除硫及灰分实验研究

煤样取自陕北横山县,该区域的煤具有高氧、低碳、低氢的特征,硫含量较高.选用该区域含硫量最高的CGC煤样人工破碎,样品筛分用标准筛,将煤样分成10个粒级,样品浮沉的重液选用ZnCl2配制,共采用了8个密度级,对10个粒级的煤样进行了实验室小型筛分浮沉实验,分析了不同粒级与不同密度级煤样的硫及灰分分布.通过研究,搞清楚了该区域煤中硫及灰分在不同粒级、不同密度级中的分布规律和脱除难易程度,为脱除方法的选择奠定了坚实的基础.     

炼焦型煤粘结剂的研究

用粒经小于0.2mm的长焰煤、焦粉与焦油按一定比例混合,制得生产冶金焦的型煤粘结剂。配入1^#煤浆粘结剂10%和3^#煤浆粘结剂8%生产型煤,均可得到较高冷强度的型煤。该粘结剂配煤制得的型煤成型率为60%～75%,抗压强度大于100N/个,落下强度大于90%,满足了炼焦型煤生产、运输和装炉过程中的强度要求。     

Ash chemistry and mineralogy of an Indonesian coal during combustion: Part 1 Drop-tube observations

The paper reports a systematic and comprehensive laboratory investigation into the ash chemistry and mineralogical changes undergone by a low-rank Indonesian coal during combustion. Combustion experiments conducted in a drop-tube furnace included ash formation experiments (using cyclone and filter arrangement) under closely controlled conditions in the range of 1200–1400 °C and deposition experiments at a probe temperature of 750 °C. Tests conducted with raw coal, coal/additive mixtures and washed coal indicated significant changes in ash characteristics. Of the ash formation and deposit samples examined, the raw coal + bauxite showed the lowest glass content and high contents of corundum indicating low ash deposition propensities. When compared to the ash formation samples, the deposit samples showed even significantly lower glass contents and were enriched in quartz. With the exception of the raw coal + bauxite sample, all are characterized by high silica and iron and moderate aluminium contents. In contrast, the raw coal + bauxite sample have low silica and much higher alumina contents which is in agreement with XRD observations. QEMSCAN™ results showed that the ash particles are sparsely distributed suggesting lack of a deposit initiation layer. Experimental observations suggest that the use of raw coal with bauxite would appear to offer the best performance with respect to handling ash-related issues. Present findings are of practical significance to power utilities employing Indonesian coal as there is no comprehensive work reported in the literature on ash chemistry and mineralogy of such coals.     

Difference in chemical composition of carbon disulfide-extractable fraction between vitrinite and inertinite from Shenfu-Dongsheng and Pingshuo coals

Vitrinite- and inertinite-rich samples separated from Shenfu-Dongsheng (SD) and Pingshuo (PS) coals were extracted with CS₂ and the extraction solutions were analyzed with GC/MS. The results show that extract yields of the two maceral-rich samples (MRSs) from PS coal are much higher than those from SD coal; for MRSs from the same coal, the yield of vitrinite-rich sample is larger than that of inertinite-rich sample; there is no remarkable difference in chemical composition from the extraction solutions between the two MRSs separated from PS coal, whereas the difference between those separated from SF coal is significant.     

基于投影寻踪的灰色聚类分析在 煤样识别中的应用*

煤炭种类识别是一个非线性灰色系统,鉴于煤样特征指标较多、其意义、量纲不同,且在数量上差异较悬殊,选用了灰色定权聚类评判模型。因指标权重对模型评判结果具有重要影响,采用了投影寻踪法计算出各指标的客观权重,以此求出煤样隶属各灰类即无烟煤、烟煤及褐煤的聚类系数。分析表明用基于投影寻踪算法的灰色定权聚类分析识别煤样种类完全可行。     

煤样破碎、缩分和干燥问题分析

分析了煤样破碎、缩分和干燥的相关问题,并给出了具体的处理方法。对于破碎后的煤样粒度要求,建议某一粒级破碎后的煤样以全部小于该粒度为宜;针对目前2种破碎煤样水分偏倚试验方法存在的问题,提出了新的水分偏倚试验方法。指出缩分后总样质量取决于煤样粒度、煤样品质不均匀性及所要求的制样精密度,分析了总样质量与各影响因素之间的变化关系;阐述了二分器缩分法、九点取样法、堆锥四分法、棋盘法、机械缩分应用中需要注意的问题。最后分析了干燥过程中,采用两步法测定全水分时第一步干燥温度不能高于40℃的原因,并归纳了空气干燥应用原则。     

Study on polypropylene–polyethylene‐based copolymer solidification

In the present work, nonisothermal crystallization is analyzed. Concretely, we study the solidification process of polypropylene–polyethylene‐based copolymers by means of differential scanning calorimetry (DSC). Several samples with different additives are subjected to artificial aging processes. The calculation of the specific surface energy, σ, is in good accordance with the results reported in the references. The artificial aging is responsible for a slight increase of σ values (i.e., increase of 1.6 kJ · m⁻² for sample A and 0.3 kJ · m⁻² for sample B). On the other hand, the σ value of sample B is considerably lower than that of samples A, C, and D (i.e., 17.3 kJ · m⁻² for sample B versus an average value of 23.0 kJ · m⁻² for the other samples). Microstructure analysis was performed by scanning electronic microscopy (SEM). As shown from the analysis, aging only affects superficial zones because no changes in the morphology of the central zone were detected in the different samples. Sample B shows a different behavior; it was less resistant to fracture. From DSC and SEM measurements, we can state the additive influence on the original sample behavior as well as on the solidification process of polypropylene–polyethylene‐based copolymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1269–1274, 2000     

煤样不同密度组分中致渣矿物特性的CCSEM研究

将一种典型的易结渣烟煤分为低（<1.3 g·cm^-3）、中（1.3～1.6 g·cm^-3）、高（>1.6 g·cm^-3）3个密度煤样。利用先进计算机控制扫描电镜（CCSEM）技术对原煤及分密度煤样中的致渣矿物进行了深入研究。结果表明,Na与K在煤中无机矿主要以硅铝酸盐的形式存在;粒径大于22 mm的外在（独立于炭基质）黄铁矿、磁黄铁矿主要分布在高密度煤中;未识别矿物（复杂硅铝酸盐）在高密度煤矿物中所占的比例最小,但其中Fe含量为20%～90%的颗粒所占比例最高;不同密度煤样中,内在（与炭基质结合）矿的硅铝比和碱酸比不同,低密度煤中内在矿的碱酸比最大,结渣倾向最严重,而中密度煤内在矿的碱酸比和硅铝比均小于原煤。     

The effects of coal dust concentrations and particle sizes on the minimum auto‐ignition temperature of a coal dust cloud

Flash fires and explosions in areas containing an enriched combustible dust atmosphere are a major safety concern in industrial processing. An experimental study was conducted to analyse the effects of atmospheric coal dust particle sizes and concentrations on the minimum auto‐ignition temperature (MAIT) of a dust cloud. Two different coal samples from Australian coal mines were used. The coal dust particles were prepared and sized in 3 ranges, of below 74 μm, 74 to 125 μm and 125 to 212 μm, by using a series of sieves and a sieve shaker. A humidifier was used to increase the moisture content of the particles to the required level. All the experiments were conducted in accordance with the ASTM E1491‐06 method in a calibrated Goldbert‐Greenwald furnace. The results from this study indicate that coal dust properties, such as the chemical nature (H/C), concentration, particle size (D₅₀), and moisture content, impact on the MAIT. For coal dust concentrations less than 1000 g.m^?3, the MAIT decreases with increasing coal dust concentrations. On the other hand, for low concentrations of 100 to 15 g.m^?3, the MAIT becomes more reliable for particle size D₅₀ rather than for volatile matters.     

Influence of physical relaxation on chemical stress–relaxation of natural rubber vulcanizates

Networks were prepared in the swollen and dry states to investigate the influence of physical relaxation on chemical stress–relaxation. The stress–relaxation behavior of solution-cured samples was different significantly from that of the samples crosslinked conventionally. The same result was also observed in the number of chain scission for both kinds of samples. On the other hand, the number of chain scission estimated by using the swelling method for samples crosslinked conventionally was in good agreement with that by the chemical stress–relaxation for solution-cured samples. It was found that there is little or no influence of the physical relaxation caused by entanglements, and no effect of dangling chains arising from scission in the equilibrium swelling. The relative change of network chain density determined by means of the swelling method was also consistent with that by sol fraction determination. These results indicate that the swelling method can be used as a measure of a degree of degradation on chemorheology. Taking into account the influence of physical relaxation on chemical stress–relaxation, a new relationship between the relative stress decay and the relative network chain density was experimentally proposed.     

Results of an inter-laboratory comparison of methods for quantitative clay analysis

In a comparison of analytical methods in clay mineralogy, two clay samples (from Hennersdorf and Freydegg) of different clay composition were analyzed by 19 laboratories mainly by XRD. Participants used different methods of pre-treatment, preparation, analysis and evaluation.In spite of the diversity of analytical methods applied, reasonable conformity in quantitative results was obtained for the associated minerals (quartz, calcite and dolomite). On the other hand, qualitative identification of the clay minerals showed considerably stronger divergencies, causing a stronger deviation of quantitative data; analysis of the Freydegg sample proved to have been particularly difficult. The evaluation methods of the different participants were examined to determine whether similar methods provided results that could be more easily compared.In addition, the authors calculated the clay mineral composition according to three different recognized methods, using the same diffractograms and same preparation and measuring conditions. In spite of this, different results were obtained.In the next phase of the programme, an inter-laboratory comparison of methods will be achieved under exactly defined conditions of preparation and analysis.     

Texaco煤气化工艺技术经济指标的评价方法与评价系统设计

目前Texaco煤气化工艺的技术经济指标评价多采用手工作业方式，工作量大而且繁琐。针对这一现状，在分析Texaco煤气化工艺流程的基础上，运用物料衡算、热量衡算方法，获得了Texaco煤气化工艺的碳转化率、冷煤气效率、比煤耗、比氧耗等指标的计算方法。通过具体计算这些评价指标，即可定性、定量地评价整个工艺系统的运行状况。在此基础上，采用VB6．0、Access7．0等开发工具，开发了Texaco煤气化工艺技术经济指标评价系统。该系统支持多用户、多数据库、多报表、多权限，界面友好，操作简单，具有很好的应用前景。