Storage of bituminous coals under argon

Two bituminous coals, crushed to < 0.32 cm ($\text{1}\text{8}$ in), have been stored for 455 days under argon at room temperature and examined for indications of oxidation. The only changes noted over this time were a 20–30% reduction in maximum fluidity from the Gieseler plastometer test for both coals, and conversion of 5% of the pyrite to iron oxyhydroxide in one coal. Although minor, these changes do indicate that more stringent conditions are necessary to minimize oxidation during long-term storage (>2 years).     

Formation of carbonaceous cenospheres during fluidized-bed combustion of bituminous coals

The discovery of cenospheres in fly ash from fluidized-bed combustors is reported and differences between the fluidized bed and more conventional combustors which are likely to affect cenosphere formation are indicated. Morphological studies and qualitative chemical analyses obtained by electron microscopy/energy dispersive X-ray specttometry (SEM/EDS) techniques show differences in composition between the ‘window’ areas of cenospheres and their ‘skeletons’.     

Action of nickel catalyst during steam gasification of bituminous and brown coals

Steam gasification of a bituminous coal and a brown coal has been carried out in the presence of a nickel catalyst. The action of catalyst particles during gasification was investigated by comparing a series of scanning electron microscope (SEM) photographs taken at stages throughout the experiment. Finely dispersed catalysts with an average diameter of <10 nm were observed upon devolatilization. During the steam gasification of bituminous coal, the carbon substrate around the catalyst was gasified. At higher catalyst loadings considerable catalyst agglomeration occurred and was associated with a decrease in effectiveness of the catalyst. On the other hand, catalyst particles remaining well-dispersed in brown coal after 80 wt% char conversion maintained an extraordinarily high activity.     

Universal size distribution of run-of-mine bituminous coals in the Eastern USA

The economic and environmental penalties resulting from the breakage of coal into fines makes it desirable to understand the breakage mechanism. This could lead to the ability to predict and perhaps minimize the generation of fines. Since breakage begins at the mine, data on size distribution of channel samples hand cut from the mine face of 159 mines in the US Appalachian range and reported by the Bureau of Mines were re-evaluated. Regression analysis to determine Rosin-Rammler constants showed the composite of all 159 coals to have a slope of 0.86 with a correlation coefficient of 0.934. The mean slope for all the coals was 0.876 with a standard deviation of < 10%. However, the Rosin-Rammler intercept showed wider variation. Other data show similar results within each group for 20 UK coals, 4 continuous-mined US coals and 4 conventional-mined US coals. However, each group differed in slope from each other. This suggests there may be a common property for similar coals within a given region, although the actual Rosin-Rammler slope is affected by the mining technique. The nature of this relationship is not understood.     

Carbonization of coals to produce anisotropic cokes.: 4. Improving co-carbonization behaviour of bituminous and subbituminous coals with pitch by pretreatment coals to remove cations

Several de-ashing pretreatments of selected coals have been examined to establish simple and effective procedures to improve, in terms of anisotropic development, the co-carbonization behaviour of the coals with pitches. Refluxing pretreatments of the coals in 1N HCI containing methanol and in boiling water containing EDTA-2Na (EDTA-2Na/coal = 7/100 byweight) improve the co-carbonization behaviour of Witbank, Miller, Taiheiyo and Wandoan coals, all of which, in their original, untreated form, are modified in terms of anisotropic development only very slightly in co-carbonizations with A240 petroleum pitch. Pretreatment of coals of very low rank appears to be ineffective in co-carbonizations with A240; however, co-carbonization with hydrogenated A240 shows that the pretreatments are effective. Analyses and FT-i.r. spectroscopy of mineral matter suggest that improved behaviour due to the pretreatment is related to the removal of divalent cations and to the modification of the oxygen functionality of the coals.     

Hydrogasification of bituminous and brown coals at 1273 K: Action of a nickel catalyst

Hydrogasification of a bituminous and a brown coal was carried out at 1273 K in the presence of nickel catalyst. The action of the catalyst during gasification was investigated using a scanning electron microscope. Contrary to what is found with steam gasification, most of the catalyst particles were spherical, due to the higher temperature. Some particles made pits and disappeared into the char matrix and others agglomerated with each other increasing the diameter of the particles significantly. Although the action of the catalyst on a brown coal was essentially similar to that on a bituminous coal, the catalyst was more homogeneously distributed over the char surface from the brown coal.     

Carbonization of coals to produce anisotropic cokes: 3. Evaluation of low-rank bituminous and subbituminous coals by single and co-carbonizations with pitch

Single carbonizations and co-carbonizations of 17 low-rank bituminous and subbituminous coals have been studied to evaluate their suitability as sources of blast furnace coke in terms of pore-wall profile and anisotropic development within the cokes. Co-carbonizations suggest the possible use of low-rank coals which from single carbonizations would not have been considered suitable. To evaluate semi-quantitatively the coke quality, two structural characteristics of the cokes produced by single and co-carbonizations are graded on a scale of 1 to 5. Overall assessments for each coal are plotted against the atomic H/C and 0/C ratios of the original coals. Although there are a few exceptions, coals with similar assessments are located in the same region of the plot, indicating that, to a first approximation, the H/C and 0/C ratios are suitable indicators of the single and co-carbonization properties of a coal. The presence of cations in the coal appears to be an additional factor influencing the carbonization properties and may explain the exceptional behaviour of some coals. Removal of these cations by pretreatment of the coals improves the carbonization properties.     

Macerals in bituminous coals and the coking process: 2. Coal mass properties and coke mechanical properties

Bituminous coals produced in the Ostrava-Karviná coal basin show considerable variation in their maceral composition, vitrinite reflectance and fluidity. There is a close association of the latter with the $\text{H}\text{O}$ atomic ratio expressing the different chemico-structural properties of vitrinites of lower coalification. These properties of the coal mass all influence the coke mechanical properties; moreover the $\text{H}\text{O}{}_{\mathrm{at}}$ parameter is of principal importance to the course of the coking process. Laboratory, pilot-plant and full-scale experiments show that coals rich in inertinite may give cokes of suitable mechanical properties, providing the $\text{H}\text{O}{}_{\mathrm{at}}$, ratio and the bulk density are high enough. It should be noted, however, that these coals contain finely dispersed inertinite in the vitrinite mass and this may have a positive effect on the coke mechanical properties.     

The mode of occurrence of chlorine in high volatile bituminous coals from the Asturian Central coalfield

The occurrence of chlorine in two high volatile bituminous coals from the Asturian Central coalfield, with a chlorine content about 0.1 wt % has been discussed. The methodology used is based on obtaining the chlorine distribution in different densimetric fractions in gravimetric solutions free of chlorides. It allows the separation of elements that could be bonded to chlorine to study their likely association. Additional information has been obtained by carrying out studies on the solubility in water, and the relation of chlorine with alkaline and alkaline-earth elements. Direct evidence of the presence of chlorine and its chemical association has been gained by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). From the results it may be concluded that in the coals studied chlorine is mainly localized in the coal matrix associated to organic matter.     

Macerals in bituminous coals and the coking process: Part 1: Effect of basic coal properties on the process of thermal degradation

Bituminous coals produced in the Ostrava—Karviná coal basin show considerable variation in their maceral composition and rank. In order to explain the significance of the petrographic composition, structure and chemical parameters in coal degradation processes, a large number of coal samples was investigated. From the relationships obtained, the behaviour of macerals during these processes is discussed. It is found that isometamorphic vitrinites are characterized by a distinctive behaviour affected to a first approximation by the atomic ratios C/H and C/O. Inertinite, despite its occasional significantly higher volatile matter, does not yield an appreciable amount of fused material.     

硫磺储存设施的设计及危险防控

硫磺是制酸原料之一,属易燃固体,且粉尘极易发生爆炸,硫磺的储存需充分考虑其危险性。随着硫磺制酸装置的大型化,硫磺储存设施的规模也逐渐扩大,危险防控压力剧增。以硫磺的物性数据为基础,结合实例介绍了硫磺储存设施设计方法,以及针对火灾和粉尘爆炸所采取的危险防控设施,为大型硫磺堆场设计工作提供可供借鉴的思路和原则。     

Dust cloud explosion characteristics and mechanisms in MgH2-based hydrogen storage materials

The mechanisms involved in premixed magnesium and hydrogen hybrid and synthetic MgH₂ dust cloud explosions were investigated. The results revealed that trace amounts of H₂ in Mg explosions can markedly increase explosion severity. Furthermore, H₂ addition can weaken the influence of oxygen deficiency on Mg explosion. Moreover, the explosion intensity of synthetic MgH₂ was far stronger than that of premixed Mg/H₂ mixture or Mg alone because the vacancy defects in Mg and H atoms can form after dehydrogenation of MgH₂, which caused that Mg and H₂ are prone to oxidation and nitrification in air atmosphere at a low temperature, thereby promoting the explosion. This demonstrates that the explosion risk of MgH₂ (even other H₂ storage materials) is related to its H₂ storage capacity and dehydrogenation temperature. Therefore, for H₂ storage materials, the better H₂ storage performances can exhibit higher explosion risks.     

Differences in the behaviour of US bituminous and subbituminous coals during short contact time liquefaction

The short contact time (SCT) liquefaction of Belle Ayr subbituminous coal has been compared with that of Illinois No. 6 and Pittsburgh seam bituminous coals. Each bituminous coal was highly solubilized (90 wt%, daf coal) in 3–4 min at 450 °C and 13–16 MPa hydrogen pressure. More than 80 wt% of each coal was converted to solvent-refined coal (SRC, pyridine-soluble residuum), with only small quantities of distillate oil and C₁–C₄ gas being formed. A longer reaction (up to 30 min) gave only a small increase in total conversion, but gas and distillate yields increased significantly. Iron sulphides did not appear to catalyse coal solubilization. By contrast, only 65 wt% of the Belle Ayr coal dissolved rapidly in SCT liquefaction and pyrite addition catalysed the conversion of the remaining insoluble organic matter (IOM). With an equivalent amount of pyrite present the Belle Ayr coal also gave more C₁–C₄ gas and substantially more distillate in SCT liquefaction than the bituminous coals. These differences in product distributions obtained from bituminous and subbituminous coals in SCT liquefaction can be rationalized on the basis of differences in the structures of the starting coals. However, the origin of high IOM yields with the Belle Ayr coal remains unclear.     

液化石油气储罐区火灾爆炸危险性评价

采用火灾爆炸危险指数评价法,对液化石油气储罐区火灾爆炸事故的危险性进行定量安全评价.根据某炼油厂在役的液化石油气球罐的数据,计算了火灾爆炸指数和考虑了防火防爆措施后的安全措施补偿系数,并估算了发生爆炸可能影响的范围和所造成的损失,提出评价结论及相应的安全对策.     

Structural differences in the tars and chars from the pyrolysis of coals of different rank in hydrogen and in nitrogen

Two British coals—Linby high-volatile bituminous and Abernant anthracite — and an Australian brown coal were pyrolysed at 575 °C in hydrogen or nitrogen at 0.1, 5 and 30 MPa in an inclined, single-stage reactor. Hydrogen pressures of ? 5 MPa led to increased yields of tars which were more aromatic than those produced in nitrogen. The high-volatile bituminous coal fused under all conditions, whereas the anthracite and brown coal fused and agglomerated only in hydrogen at 30 MPa.     

碳纳米管储氢性能的研究进展

介绍了单壁碳纳米管和多壁碳纳米管对氢气的吸附实验和模拟计算研究进展;综述了该领域的最新研究成果;讨论了碳纳米管储氢性能的可行性和应用前景。     

提高水泥厂用烟煤氢含量计算值精度的方法

本文根据水泥厂用烟煤多为配煤的特点,以公司进厂烟煤数据为基础,参照经典经验公式,利用Excel数据分析工具建立数学模型,推导出适合公司的烟煤氢含量计算公式,对实测值与按经典经验公式和新推导公式的计算值进行统计对比,并进行置信分析,确定出新的推导公式满足计算精度要求,从而提高了氢含量计算值的准确度。     

Measurement of true specific heats of bituminous coals of different rank,and of a high-temperature coke,in the temperature range 30–350 °C

The true specific heats of four bituminous coals from the Ruhr district with volatile matter ranging between 9 and 37 wt% and of a high-temperature coke were measured with an adiabatic metal calorimeter. The precision of the equipment was checked by measurements on pure nickel, with the result that the experimental values were found to differ by <1% from the adequately accurate average values given in the literature. The results of this study and the scrutiny of all obtainable systematic specific heat measurements of bituminous coals lead to the conclusion that, contrary to the opinion given in the literature, the specific heats do not increase rectilinearly with the volatile matter. The relation of the specific heats of the coals investigated to volatile matter and temperature can be explained by the chemical composition and structure of the coals. The specific heats calculated from the distribution of the elements carbon, hydrogen and oxygen in the structural groups of bituminous coals correspond well to the experimental values. The procedure is more promising than that using only the results of immediate analysis without taking into account chemical composition and structure. In the initial stage of pyrolysis, variations from a monotonic increase are observed and semiquantitative considerations on this are given. The effect of temperature on the specific heats of coals is compared with that on other physical quantities and explained.     

水平管道内障碍物对气体爆炸压力影响的研究

随着煤矿机械化生产水平的提升,煤矿巷道内机械设备已经其它固定设备的增多,在瓦斯爆炸的传播过程中障碍物的影响研究越来越被人们所重视。本论文利用管道式气体爆炸测试装置,分别在光环管道内和放有障碍物的水平管道内充入当量浓度的甲烷气体对其爆炸过程进行了较深入的实验研究。结果表明：随着障碍物的阻塞率增大,管道内气体爆炸的最大爆炸...     

Dependence of carbon dioxide sorption on the petrographic composition of bituminous coals from the Czech part of the Upper Silesian Basin, Czech Republic

The effect of the rank and of the maceral composition of bituminous coal on carbon dioxide sorption capacity was studied on the basis of samples from two coal mines (Darkov, ?SM) from the Czech part of the Upper Silesian Basin. The samples from the two mines cover a small but very significant section of coalification within the transition zone between high-volatile bituminous A coal and medium-volatile bituminous coal, where porosity and sorption properties pass through their minima. The coal porous system was characterized by the micropore volume evaluated using the sorption isotherm of carbon dioxide and the volumes of meso-, macro- and coarse pores were determined by high-pressure mercury porosimetry. The micropore fraction in the coal porous system ranged between 53% and 75%. It was particularly high in coals with high vitrinite content, namely collotelinite, and also in coals with high inertinite content. The carbon dioxide sorption capacity was determined from the carbon dioxide sorption isotherms measured using a gravimetric sorption analyzer at 298 K until a relative pressure of 0.015 p/p_s, and was interpreted by characteristic parameters of the Dubinin and Langmuir equations. It was found that the adsorbed amount of CO₂ in the ?SM coal increases with the content of vitrinite and collotelinite, whereas no increase or only a slight increase was observed for the Darkov coal. The tendency of adsorption capacity to depend on maceral composition, and also to some extent on coalification, observed for the ?SM coal, may be related to higher microporosity due to the coalification process or oxidative processes leading to the formation of pseudovitrinite.