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The ultrafine coal water slurry (CWS) with the particle size of 1-10 μm, ash content of 1-2%, solid concentration of 50% is a promising substitute fuel for diesel oil. The effects of pore fractal structures of three ultrafine CWSs on their rheological behaviors and combustion dynamics were studied in this paper. When the pore fractal dimensions of Yanzhou, Huainan and Shenhua ultrafine CWSs increase, their apparent viscosities all increase and the increase extents gradually enlarge with decreasing shear rates, while their ignition temperatures and apparent activation energies all decrease. For example, when the pore fractal dimension of Yanzhou coal increases from 2.31 to 2.43, the CWS apparent viscosity at a low shear rate of 12 s−1 increases from 75 mPa s to 2400 mPa s, and that at a high shear rate of 100 s−1 increases from 80 mPa s to 820 mPa s. Meanwhile, the ignition temperature of Yanzhou CWS decreases from 445 °C to 417 °C at a heating rate of 12.5 °C/min, and the apparent activation energy decreases from 104 kJ/mol to 32 kJ/mol. 相似文献
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Upgraded brown coal water mixture (UBCWM) preparation by using an Indonesian upgraded coal produced by upgraded brown coal (UBC) process, was carried out to study the effect of dispersing and stabilizing additives on rheological behavior of the UBCWM. Three kinds of anionic dispersing additives, naphthalene sulfonic formaldehyde condensate (NSF), poly (meth) acrylate (PMA) and poly styrene sulfonic acid (PSS) and three kinds of stabilizing additives, carboxyl methyl cellulose (CMC), rhansam gum (S-194) and gellan gum (S-60) were used in this study. Results indicate that the addition of NSF 0.3 wt.% together with S-194 0.01 wt.% is effective in preparing UBCWM with good slurryability and stability, based on its rheological characteristics with the apparent viscosity at shear rate of 100 s− 1 and yield stress at zero point of shear rate. The rheological behavior of all of the UBCWM that prepared, exhibits non-Newtonian Bingham plastic. From the economical point of view, the price of S-194 is expensive. On the other hand, CMC is cheap and abundant. Therefore, the addition of CMC 0.01 wt.% together with NSF 0.3 wt.% is also effective in preparing UBCWM with good fluidity and stability. 相似文献
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周从文 《化学工业与工程技术》2013,34(4):31-33
以某煤制烯烃项目为例,介绍了GE水煤浆气化炉生产工艺的磨煤和级配流程,对棒式磨煤机配置和选择进行了分析和讨论,得出科学的选择方案,对类似工程项目的建设有指导意义。 相似文献
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在浆体流动试验系统上采用不同管径的直管考察了水焦浆的流变特性以及壁面滑移效应对水焦浆流动特性的影响。采用Tikhonov 正则化方法确定了水焦浆的真实流变特性和壁面滑移特性。结果表明:浓度为59.8%的水焦浆随剪切速率增大呈现由伪塑性流体到胀塑性流体的转变,浓度增加,水焦浆变为单一的胀塑性流体,当浓度达到63.4%时,水焦浆表现为由胀塑性流体到伪塑性流体的转变;水焦浆的流变特性对滑移速度的变化趋势具有较大影响,滑移速度在水焦浆为胀塑性流体时随剪切应力增加呈加速增加,水焦浆为伪塑性流体时滑移速度随剪切应力的增长速率变化不明显;滑移贡献率的变化趋势迟滞于流变特性曲线。 相似文献
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将安徽的煤种G煤灰和煤种S煤灰分别与神府煤灰进行混合,对混合灰的熔点进行了研究。通过实验,发现随着煤种G煤灰的比例增加,混合灰的DT、ST和FT先降低,然后提高。而混合灰中煤种S煤灰的比例越高,混合灰的DT、ST和FT越高。同时实验表明,混合灰的熔点并不随混合灰中G煤灰或者S煤灰含量的提高成正比地提高。 相似文献
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Performance characteristics of cement grouts made with various combinations of high-range water reducer and cellulose-based viscosity modifier 总被引:8,自引:0,他引:8
Cellulose-based viscosity-modifying admixtures (VMA) are used to increase the viscosity of cement-based systems, hence, reducing the risk of material separation during handling and transport and thereafter until the onset of hardening. To ensure proper fluidity such admixtures are incorporated along with high-range water reducers (HRWRs). The ability of the VMA to ensure the required rheological properties depends on the type and interaction with the incorporated HRWR. Good understanding of such interaction is essential to ensure adequate performance. Limited knowledge is available on the effect of cellulose-based VMA and HRWR on physico-chemical characteristics and cement hydration.
The performance of grouts made with 0.40 water/cement (w/c) ratio containing a liquid-based cellulose material was investigated for mixtures made with polynaphtalene sulfonate (PNS) and polymelamine sulfonate (PMS) HRWR. The grouts are tested for fluidity, rheological properties, stability, setting and rate of hydration. The grouts were also tested for strength and pore-size distribution, and microstructural characteristics.
This paper summarizes the results of the study regarding the influence of the type and dosage of HRWR on key characteristics of grouts made with the cellulose-based VMA. 相似文献
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通过对石圪台选煤厂煤泥水浓度和粒度组成的分析,发现煤泥水中高灰细泥含量较高,为煤泥水处理带来困难。通过现场药剂和自配药剂的絮凝沉降试验以及药耗分析对比,找出影响煤泥水处理的关键因素,并提出了相应的改进措施。 相似文献
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利用居里点裂解仪对水煤浆和原煤粉进行中速热解。介绍了居里点裂解仪的工作原理,计算了2种样品在实验中的热解动力学参数和升温速率,对比分析2种样品中速热解时的反应特性。结果表明,水煤浆的活化能为16.362 kJ/mol,大于原煤粉的活化能12.691 kJ/mol,但升温速率比原煤粉小,分别为617 K/s和834 K/s。实验还发现水煤浆因为其中水分的影响,其挥发分的热解有明显的滞后,但热解曲线的斜率比原煤粉大,说明水煤浆在经过热力储备阶段达到热解的活化能后其热解速率比原煤粉要快,最终的产量也稍高。 相似文献
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针对中国储量丰富的低阶煤难以制备高浓度水煤浆的问题,介绍了国内先进的低阶煤制浆技术。制备高品质低阶煤水煤浆,应结合煤质特性,选择适宜的磨矿技术、提质改性工艺、配煤技术或添加剂,制备符合工业化应用的高性能低阶煤水煤浆。同时指出,低阶煤制备水煤浆技术是适合中国国情的洁净煤技术,是目前国内对低阶煤合理利用的一条新途径,低阶煤水煤浆的研究和发展为解决中国环境污染问题和能源合理利用问题提供了广阔的前景。针对目前中国低阶煤水煤浆的发展状况,对中国低阶煤制备水煤浆技术发展前景进行了展望。 相似文献
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为了考察复配分散剂对不同煤化程度煤的成浆性能的影响,以木质素磺酸钠与萘磺酸钠复配分散剂对山西王坡煤(WP)、淮北朱仙庄煤(ZXZ)、内蒙古上湾煤(SW)3种不同煤化程度的煤样进行了制浆试验。结果表明:复配分散剂对上湾煤样所成浆的流动性和稳定性产生较大影响,但成浆浓度不高;对较高煤化程度煤样的成浆性提高效果明显,选用3号分散剂王坡煤的成浆浓度达到最大66.8%;朱仙庄煤选用4号分散剂可以制成流动性和稳定性较好的煤浆,其煤浆浓度达67.0%。木质素磺酸钠及萘磺酸复配分散剂的协同作用对不同煤化程度煤样成浆性的影响与煤的结构有关,此复配分散剂对煤化程度较高煤的成浆性提高较有利。 相似文献
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描述了中国水煤浆燃烧技术的发展历程和现状,并对水煤浆燃烧技术的关键设备进行介绍和分析,最后分析了水煤浆燃烧技术未来的发展方向。 相似文献
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利用神华、兖州和淮南3种煤制备了精细水煤浆,并对精细煤粉颗粒的粒度分布与表面分形特征、精细水煤浆的流变特性和不同升温速率下的燃烧特性进行了研究。结果表明随着精细煤粉的表面分形维数增大,其比表面积增大,粒度、孔径均相应减小,相同浓度下的精细浆的表观黏度值上升,精细水煤浆的着火温度和燃烧反应活化能降低。其中表观黏度值以淮南精细浆与兖州精细浆增加较多,在100 s-1下都增加了740 mPa·s。着火温度和燃烧反应活化能都以淮南精细浆降低最多,其着火温度降低了41.36℃,燃烧反应活化能降低了77.71 kJ·kmol-1。 相似文献