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991.
992.
在φ476 mm的鼓泡塔内,以0.1~1 m·s-1的高气速,利用Pavlov管测量塔内不同位置液相轴向速度,通过能谱分析发现,在空间区域上采用该方法测得的速度时间序列可分为含能尺度区和惯性子区,再借助7尺度Daubechie2小波分析的方法实现湍流量化指标如局部间歇性测度、间歇指数、尺度能量、涡旋尺寸等的评估.实验结果表明,高频和低频尺度下LIM峰分布表明湍流相干结构和大涡旋与小涡旋串级结构的存在.各小波尺度能量的比较说明,气速增大,高频和低频尺度的能量均增大,其中,含能尺度区间的能量占总能量的97%以上.不同尺度涡旋尺寸的计算证实了接近于塔内径最大涡旋的存在.进一步分析表明,塔壁处的涡旋尺寸约为塔中心处的2倍,含能尺度区间的涡旋尺寸为0.03~0.35 m,气速对涡旋尺寸的影响可以忽略.湍流量化指标的分析有助于揭示湍流中的隐含结构以及高气速下鼓泡塔内湍流流动规律. 相似文献
993.
994.
A suite of density-differentiated macerals from several coals was analysed by Fourier transform infrared spectroscopy to obtain information on the nature and magnitude of the variations exhibited by the various maceral fractions. The most characteristic change between maceral groups was the variation in aliphatic hydrogen content, with exinite ? vitrinite ? inertinite. Since the separation technique (density gradient centrifugation) generally provided a number of fractions within a maceral group region, some of these were also analysed. In a series of density fractions from a low rank vitrinite, it was found that the aliphatic hydrogen content decreased as the density increased. The inertinites also exhibited a decrease in aliphatic hydrogen. The inertinite C—O bands had extinction coefficients different from those of vitrinites or exinites. The data suggest that quite profound variations in organic structure as determined by FT-i.r. spectroscopy can exist within a maceral group, so that for the most critical work on coals it is necessary to take this into account. 相似文献
995.
The relations between coke yields and the volatile matter content of 30 individual and 30 blended coals were investigated. Coke yields and deposited carbon related to volatile matter content can be expressed in the following equations: CY (%) = 97.89?0.86 VMch+VMc; and DC (%)= ?2.24+0.16 VMch; where: CY=real coke yield; VMch = volatile matter content of charging coal; VMc=volatile matter content of coke, and in the case of <2%; DC = deposited carbon. The test results show excellent correlation with practice. 相似文献
996.
Isao Mochida Hideichi Matsuoka Yozo Korai Hiroshi Fujitsu Kenjiro Takeshita 《Fuel》1982,61(7):587-594
Using low-rank coals, the modifying activities of some petroleum, coal tar and aromatic hydrocarbon additives have been examined to find procedures for their utilization in the preparation of blast furnace coke. Petroleum pitch, especially after hydrogenation, exhibited excellent modifying activity even with non-fusible coals. In contrast, the activity of coal tar was very limited with such coals. The napththenic component, revealed by n.m.r. of the additives, appears to be important in the co-carbonization by inducing fusibility and anisotropic development in such coals. Co-carbonization to recover the dehydrogenated additives was attempted. However, there was no development of the anisotropy in the resultant coke by dissolution of the coal particles although the coal particles were firmly fixed in the matrix. Acid-refluxing treatment of non-fusible coals was found to enhance their modification susceptibility, indicating that some of the acid-soluble mineral matter is important in the thermal depolymerization or fusion process of the coal. 相似文献
997.
The Mössbauer effect has been used to study the transformations of FeS2 in four different coals: IL No. 6, Ky , Blacksville No. 2, and Powhatan No. 5. The transformations of FeS2 in the coals were studied in an inert atmosphere. It was observed that the pyrrhotites formed from FeS2 have a considerable reduction in the isomer shift at 440 °C as compared to the values obtained in the absence of coal. This effect is associated with the interaction of the pyrrhotites with the coal constituents at high temperatures. There is also a significant line-broadening at 440 °C. This broadening is due either to vacancy motion in the iron sulphides and/or to motional broadening due to particle motion in the coal-derived liquids. The percentage conversion of pyrite to pyrrhotite depends markedly on time as well as type of coal. The weathering of the coal has a detrimental effect on the rate of conversion of pyrite to pyrrhotite. The ferrous sulphate layers covering the pyrite particles hinder the removal of sulphur from that surface. The major factor affecting the ratio is the total amount of sulphur available for H2S formation. Partial H2S pressure is the crucial quantity controlling the stoichiometry of the pyrrhotites. Hence, a high percentage of H2S in the reactor at high temperature will assure the formation of pyrrhotites with a high number of metal vacancies. 相似文献
998.
57Fe Mössbauer spectroscopy has been used to characterize the iron-bearing minerals present in some British Columbia coals. The minerals observed in a range of samples include pyrite/marcasite, siderite, jarosite, rozenite or melanterite, and Fe2+ -bearing clay minerals such as illite. The presence of jarosite is confirmed through the magnetic hyperfine interaction observed at 4.2 K. The absence of magnetic ordering at 4.2 K for the ferrous sulphate component indicates the presence of rozenite, FeS04 · 4H20, or melanterite, FeS04 · 7H20, rather than szomolnokite, FeS04 · H20 or FeS04. The effects of ashing on two of the coals is also studied. 相似文献
999.
Bituminous coal samples from 84 distinct sources were analysed by conventional British Standards (BS) methods for phosphorus, sulphur, chlorine, ash and the ash-forming elements (calcium, silicon, aluminium, iron, sodium, magnesium, potassium, titanium and manganese). In most cases four determinations were made per element per source. Samples were crushed to ?212 μm (72 BS mesh) and pressed into aluminium cups at 20 t in?2 (309 MPa) without binder or backing. Two pellets from each sample were analysed by wave-length dispersive X-ray fluorescence techniques, using a spectrometer equipped with a rhodium rube; the X-ray count took 60 s. The X-ray results were calibrated against the conventional results using multiple regression. The accuracy obtained was comparable with routine ‘wet chemical’ techniques. The X-ray technique is suitable for the routine determination of large numbers of samples. 相似文献
1000.