中亚造山带中的燃烧变质事件及其年代学研究

Combustion metamorphic(pyrometamorphic)complexes produced by prehistoric natural coal fires are widespread inCentral Asia,namely at the interfaces between mountain systems and the flanking sedimentary basins.Large-scale and prolonged firesaccompanied the initial orogenic stages as unweathered coal-bearing formations became exposed into the aeration zone.Pyrometamorphic rocks are comparable to sanidinite facies rocks in formation conditions and in alteration of sedimentary material but,unlike these,their protolith underwent different melting degrees to produce either ferrous basic paralavas or glazed clinkers.The phasecomposition of the newly-formed melted rocks are favorable for~(40)Ar/~(39)Ar dating of combustion metamorphic events which are coeval tothe onset of the main stage of recent orogenic events.We suggest a new algorithm providing correct ~(40)Ar/~(39)Ar dating ofpyrometamorphic rocks followed by well-grounded geological interpretation.We studied pyrometamorphic rocks in the western Salairzone of the Kuznetsk coal basin where combustion metamorphism under temperatures above 1000℃acted upon large volumes of coal-bearing sediments.Samples of paralavas were dated by the step heating ~(40)Ar/~(39)Ar method checked against internal(plateau andisochrone ages)and external("criterions of couple")mineralogical criterions,and against preliminary dating from geological andstratigraphic evidence.As a result,we distinguished two groups of dates for combustion metamorphic events.The first one(1.2±0.4Ma)is drawn towards the west boundary of Prokopyevsk-Kiselevsk block of Salair zone,while the second one(0.2±0.3Ma)isconfined to its east boundary.The former ages represent rocks in the western edge of the Prokopievsk-Kiselevsk block of the Salair zoneand the latter ages correspond to those in its eastern edge.The dates record the time when the fault boundaries of the blocks wererejuvenated during recent activity and the block accreted to the Salair orogenic area as a piedmont step.These are the first absolute agesobtained for the onset of uplift of the northern edge of the Ahai-Sayan area,the key event of its neotectonic history.The suggestedapproach to the choice of objects,classification of rocks,and interpretation of~(40)Ar/~(39)Ar data is universal and can be practiced in anyarea subjected to combustion metamorphism.     

燃烧加热污染空气对超燃冲压发动机性能影响研究

针对燃烧加热地面试验设备存在的工质污染问题,采用数值模拟方法研究了燃烧加热污染空气对氢燃料超燃冲压发动机性能的影响。以飞行马赫数Ma=6.5,当量油气比ER=0.6为计算基准状态,分别对纯净空气和污染空气来流下氢燃料超燃冲压发动机的整机流场和性能进行了对比计算分析。燃烧化学反应模拟采用了改进的H₂/O₂七组分八方程模型,湍流模型为标准的 k-ε模型,并采用直连式燃烧室试验数据进行了数值方法的验证。研究结果表明:(1)相对于纯净空气来流,污染空气来流下的超燃冲压发动机推力和比冲均有所下降。(2)采用酒精燃烧加热器的前提下,来流参数匹配静温、静压、马赫数时,发动机性能与纯净空气来流下的结果最为接近,而匹配总温、总压、马赫数时相差最大。(3)来流参数匹配总焓、静压、马赫数的前提下,采用氢燃烧加热器时发动机性能与纯净空气来流下的结果最为接近,而采用甲烷燃烧加热器时相差最大。      

Photocatalytic Activity of Combustion Synthesized Nanocrystalline CeAlO3

The photocatalytic activity of combustion synthesized nanocrystalline CeAlO₃ was determined for the degradation of four anionic and four cationic dyes. The perovskite oxide showed high‐photocatalytic activity and a complete degradation of all the dyes was possible within 2 h. The photocatalytic activity of the compound was comparable with the activity of the commercial Degussa P‐25 TiO₂ catalyst. The degradation of dyes was found to follow first order kinetics and the first order degradation rate constants were determined.     

The interaction between multiple high pressure combustion gas jets and water in a water-filled vessel

A static experimental system based on the background of the underwater gun firing process is designed to simulate the expansion of conical-distributed multiple gas jets in a water-filled vessel. The gas is generated from the gunpowder combustion and injected into water through five orifices on a mock bullet. A high-speed digital camera is taken in experiment to record such expansion and the Euler-Euler multiphase model is utilized in simulation to describe the gas-liquid flow. Results show that the contraction of Taylor cavity in liquid and the gas-liquid entrainment both affect the shock structure in gas. The expansion zone near the orifice shrinks and the gas speed downs when the central gas jet has a contraction, but lateral jets have no contractions due to the obstruction from the wall. The contraction has a greater impact on the shock structure than the gas-liquid entrainment and occurs earlier under a higher injection pressure.     

New directions in black carbon organic geochemistry

In the past 30 years, the field of black carbon (BC) research has expanded broadly, stretching from its traditional core in the atmospheric sciences into oceanography, soil science, and even anthropology. Results produced in this period of expansion have been exciting: BC has been detected in many important geochemical pools, and interesting new research directions open as we learn about the role of this byproduct of biomass burning in the carbon cycle. Especially important research directions will be the quantification of BC loss processes (both biotic and abiotic), measurement of BC decomposition products in environmentally relevant reservoirs, and exploration of the interactions between BC and its host organo-mineral matrix, including the role of BC in pedogenesis.However, along with exciting results, we have also seen apparent discrepancies between BC studies. These discrepancies occur at least in part because of a lack of a common language, common methods, and a common model of BC. This paper lays out the framework many BC researchers use to understand the role of BC in the carbon cycle, discussing the ‘combustion continuum’ BC model and the methodological continuum that this model implies.     

Geology and characterisation of the Pecket coal deposit, Magellan Region, Chile

The geology, petrography and chemical variation of the Pecket coal sequence, Magellan Region (52°57′S, 71°10′W), the only Chilean coal used for electricity generation on a large scale, has been studied in order to predict their combustion behaviour, especially in coal blends. The depositional environment of formation of the coal seams was a swamp rarely exposed to subaerial conditions and was associated with the development of the folded foreland of the Magellan basin during the Tertiary (Oligo–Miocene). The general tectonic regime of the collision of the Antarctic and South American plates is reflected by a system of joints with 40°N–50°W strike. The maceral composition of all six seams studied indicates high contents of vitrinite (>90%), minor content of liptinite (4.7%) and inertinite (<2%). Occurrence of tonstein horizons altered to kaolinite indicates a distal volcanism during peat accumulation. Coal rank varies between lignite and subbituminous (Ro=0.28–0.42%) with an average dry basis calorific value of 5450 kcal/kg, 17 wt.% moisture, 41 wt.% volatile matter, and sulphur content below 0.5 wt.%. The mineral matter (LTA) associated with the coal shows a dominance of kaolinite with quartz, smectite, and minor basanite. SiO₂/Al₂O₃ and Fe₂O₃/CaO ratios of the ashes diminish towards the lower seams. With respect to the utilisation of Pecket coals in combustion, base/acid ratios (B/A) and silica ratios (SR) indicate potential fouling for seams 1, 2, 5, and 6i, with high fouling indexes (Rf) for seams 2 and 5. Pecket coal is excellent for blend combustion due to its low sulphur content.     

Maceral/ microlithotype partitioning with particle size of pulverized coal: Examples from power plants burning Central Appalachian and Illinois basin coals

Pulverized coals from eleven power plants burning Central Appalachian coal blends and eight power plants burning Illinois Basin coal blends were studied in order to assess the petrographic nature of industrial-scale coal grinding. All coals were high volatile bituminous. Coals were wet screened at 100 (150 μ), 200 (75 μ), 325 (about 40 μ), and 500 (about 25 μ) mesh. Petrographic analysis of the whole coals and size fractions consisted of a combined maceral and microlithotype analysis. Microlithotype analysis, in particular, provides a reasonable approximation of the whole-particle composition at the scale of utility coal pulverization. In the size fractions, duroclarite, the most abundant trimaceral microlithotype, is most abundant in the coarsest fraction and least abundant in the finest fraction. Vitrite, the most abundant monomaceral microlithotype, exhibits the opposite trend. Duroclarite becomes more enriched in vitrinite towards the finer sizes. The partitioning of microlithotypes and the partitioning of macerals within the microlithotypes is indicative of the relative brittle nature of vitrite compared to the hard-to-grind trimaceral microlithotypes. Increased vitrinite in duroclarite is an indication that the microlithotype within the particular size fraction is more brittle than relatively vitrinite-depleted duroclarite in coarser fractions. The relative grindability of microlithotypes will, in turn, impact combustion efficiency.     

鄂尔多斯盆地北部地区延安组煤层自燃烧变产物及其特征

煤层自燃是世界范围内普遍存在的一种地质现象,但针对煤层自燃形成的产物尚缺乏系统研究。我国鄂尔多斯盆地北部地区延安组煤层在地史时期普遍发生自燃,研究中主要针对该地区的煤层自燃烧变产物的特征进行系统分析。结果表明,煤层烧变产物包括烧变残留煤、煤灰、烧变岩三类,其纵向和横向剖面上具有明显的分带规律,对其岩石物理学、地球化学等特征分析显示较原岩(煤、泥岩、砂岩)发生了不同程度的变化,可将其看成一类特殊的变质岩类。     

甘氨酸-硝酸盐燃烧法制备Ca0.3Sr0.7TiO3介电质材料

采用甘氨酸-硝酸盐燃烧法,以硝酸锶、硝酸钙、钛酸丁酯和甘氨酸为原料合成了Ca0·3Sr0·7TiO3陶瓷粉体。对影响粉体特性的两个主要因素pH值和原料配比进行了讨论。XRD结果表明,所得粉体结晶好,纯度高。用所得粉体经1420℃烧结成瓷,介电频率特性测试结果表明,介电常数随频率单调递减,50kHz到10MHz范围内,介电常数基本稳定在140~150之间。介电损耗随着频率的增大先减小后增大,最小介电损耗在1MHz下为0·0243。