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991.
煤炭地下气化反应动力学特性的研究 总被引:6,自引:3,他引:3
煤炭地下气化过程中,高温的碳与二氧化碳和水蒸气发生的非均相反应决定了出口煤气的组分和热值。鉴于此,在煤焦与CO2和H2O(g)反应活性实验的基础上,研究了唐山刘庄煤焦与CO2和H2O(g)气化反应的动力学特性,确定了其化反应的速率表达式,得出其反应活化能分别为140.41kJ/mol和171.53kJ/mol。实验结果表明,还原带温度在1000℃-1100℃时,CO2具有较高的还原主;温度达1000℃时,H2O(g)分解可视为不可逆反应,且生成CO的反应速率明显大于生成CO2的反应速率,出口煤气组成中CO的浓度为CO2的7倍多,在上述工作的基础上,建立了“收缩反应核”模型,并分析了多相化学反应速度与温度的关系。 相似文献
992.
The mineral matter associated with coal undergoes various transformations during the coal gasification process. Optimisation of the gasification process is necessary in the coal to liquids technology. The principle aim of this investigation was to determine the changes that the Fe-containing minerals and mineral associations undergo during gasification of coal. Due to the complexity of the counter-current coal-gas process used, a gasifier dissection was undertaken on one of the Sasol gasifiers. Detailed characterisation profiles of various properties of the coal were undertaken after a commercial-scale gasifier was shutdown for routine maintenance of which the Mössbauer spectroscopy technique will be described here. Representative samples from the gasifier were extracted after sufficient cooling was done to allow the safe turn-out of the gasifier. In the coal samples that entered the gasifier, pyrite was the abundant Fe-containing mineral, whilst the pyrite changed gradually to form, in conjunction with the SiO2 and Al2O3 present in the coal, a Fe-containing glass and hematite at the bottom, or ash grate of the gasifier. 相似文献
993.
994.
燃煤过程中As,Se的挥发行为的研究 总被引:2,自引:0,他引:2
本文首先运用热平衡分析法对不同气氛下三种煤样的燃烧系统中As,Se物质的分布及含量进行了预报,并以此来指导实验方案的设计,最后,进行相应的实验研究,来探究燃煤过程中As,Se的挥发行为特性。从研究结果我们可以得出: (1)As,Se的挥发量都随着温度的升高而增加,并且Se的挥发百分比要比As要大。(2)在氮气气氛下,As挥发量大幅提升的现象发生在600-900℃这一温度范围,而Se的大量挥发现象比As要早,大约在200-600℃的温度范围内。 (3)氧化性气氛有助于As,Se在更低的温度下的挥发。 (4)SO2在某一温度范围内对于两种痕量元素的挥发有微弱的促进作用。 相似文献
995.
Acoustic analysis of the speaking voice after thyroidectomy 总被引:1,自引:0,他引:1
Voices of 47 female patients were analyzed before and after thyroidectomy, with preservation of the recurrent and superior laryngeal nerves and normal vocal fold motility during the observation period. A mean decrease of the speaking fundamental frequency (SFF) of 12 Hz was found on day 4; in 8 patients the postoperative vocal pitch was more than 2 semitones lower. The distance between the highest and lowest F0 during speaking was diminished (speech was more monotone) and the vocal jitter was elevated. In the frequency spectrum, there was a diminished prominence of the harmonics. The other spectral parameters (as the slope of the spectrum and the H1/H2 ratio) were unchanged. All changes had disappeared the fifteenth day, except for a lower SFF (>2 semitones) in 2 cases. It is concluded that after normal dissection of the laryngeal nerves, and in the absence of vocal fold paresis, other reasons for voice changes immediately after thyroidectomy remain: alterations in the neck muscles, in the laryngeal mucosa, and in the patient's general condition. Although the effects seem limited and of short duration, knowledge of them is helpful when informing the patient before thyroid surgery. 相似文献
996.
997.
Progresses of coal liquefaction catalysts in Japan 总被引:2,自引:0,他引:2
Isao Mochida Kinya Sakanishi Nobuo Suzuki Masaaki Sakurai Yutaka Tsukui Takao Kaneko 《Catalysis Surveys from Japan》1998,2(1):17-30
Research and development of catalysts and their performances for coal liquefaction are reviewed, enphasizing the contribution of recent 20 years from Japan. A variety of iron based catalysts were extensively examined to define the pyrrhotite as the active species produced in the liquefaction process. Synthetic pyrite, synthesized hydroxy ferric oxide, finely ground pyrite and limonite have been applied in the process development of coal liquefaction. Iron impregnation onto coal particles using waste water was examined also in a continuous-flow reactor. Finer particles were found to reduce significantly the amount of the catalyst to obtain the same oil yield. Usefulness of such catalysts is proved in the continuous operation of a large scale pilot plant. Iron, iron–nickel, and iron–molybdenum sulfides were found to be active catalysts when they are supported on nano-particles of carbon. Catalysts for recovery and repeated use and for selective aromatic ring opening are under current research. 相似文献
998.
煤微观结构的X射线衍射原子分布函数分析 总被引:2,自引:0,他引:2
采用在非晶态结构研究中应用的X射线衍射原子分布函数法测试了四种不同煤化程度煤的碳原子平均径向分布,求出了碳原子间距、配位数、芳香度、聚合度和短程有序畴等结构信息,并与文献值进行了以比。结果表明,煤的碳原子间距及对应的配位数介于石墨和金刚石对应的数值之间,随着煤化程度的增加,芳香胺、聚合度和短程有序畴增大,煤的石墨化程度增加。 相似文献
999.
本文将贴体坐标用于具有复杂形状的船型体煤粉燃烧器的三维流场数值模拟中,建立了在贴体坐标下的总体质量校正方程。计算结果令人满意。同时,对存在的问题作了进一步讨论。 相似文献
1000.
波浪与风载的共同作用下,海上风电机组平台存在多自由度运动,同时伴随着海上复杂的风况,其气动特性变化较为复杂。以NREL5MW风电机组为研究对象,在风剪切来流下,依据波浪和风载的作用规律,研究平台纵摇和纵荡运动对机组气动特性和绕流场细节的影响。结果表明:平台运动会造成风电机组气动性能的周期性波动,而风剪切作用使得风电机组平均发电量降低并加剧功率和推力的波动。风剪切会增大纵摇运动过程中展向截面的法向载荷幅值且波动加剧,但会降低与功率输出有关的切向受力;风剪切作用推迟了纵荡运动过程中展向截面法向和切向载荷峰值出现时刻,加剧载荷的波动。外叶展截面的法向和切向力系数曲线出现平台,加剧了叶片疲劳载荷,减小了功率输出。 相似文献