溶损反应动力学对焦炭溶损后强度的影响

为了分析溶损反应动力学行为对焦炭反应后强度的影响,在1 050℃～1 300℃的范围内,对三种典型焦炭进行了等温溶损反应实验.当焦炭的溶损失重率为25%时停止反应,通过I型转鼓检测焦炭的溶损后强度.结果表明,不同反应性的焦炭发生最严重的劣化梯度反应时的温度不同,高反应性焦炭为1 100℃左右,低于其他两种焦炭.虽然高反应性焦炭发生最严重的劣化梯度反应后的强度很低,但改变反应温度使反应速率加快或减慢都能使高反应性焦炭的反应后强度显著地提高.     

不同配比碱金属化合物对焦炭反应性的影响

通过将一定粒度焦炭浸入不同配比碱金属化合物（K2CO3＋Na2CO3）溶液的方法在实验室制得焦样,用热重天平对焦样进行了焦炭反应性实验及SEM扫描电镜和能谱分析。研究结果表明,不同配比碱金属K、Na复合催化剂催化效果不同,K2CO3对焦炭溶损反应的催化作用贡献较大,焦炭溶损反应主要催化作用时间为前10min,浸碱焦炭试样中K、Na含量随碱溶液中K、Na含量增加而增加。     

碳溶反应温度对高反应性焦炭热态性能的影响

以钢渣为催化剂添加至焦煤中制备高反应性焦炭,研究碳溶反应温度对焦炭热态性能的影响及焦炭反应后的结构变化。结果表明,添加钢渣后,焦炭的反应性提高;随着碳溶反应温度的升高,焦炭的反应性呈线性增加,而反应后强度先缓慢降低然后迅速劣化;焦炭反应后的比表面积先增大而后减小。     

典型碱金属、碱土金属对不同变质程度煤焦溶损反应的催化作用

试验研究发现,添加碱金属、碱土金属对低变质程度煤焦反应性的催化作用小于焦煤等中等变质程度煤焦反应性。它们对焦炭溶损反应的催化作用顺序为：K〉Na〉Ca〉Mg,且随着添加量的增加,催化作用越强。随反应时间和典型金属添加量的增加,以及温度的升高,焦炭转化率越大。     

焦炭反应性及反应后热性质及其检测方法

通过焦炭反应性(CRI)和反应后强度(CSR)在模拟高炉内焦炭热性质中存在问题的分析,提出了CRI和反应后热性质(PRTP)及其检测方法,指标包括溶损反应开始温度、溶损速率、等溶损率后强度、反应后热处理性和热处理后强度. 7种高炉用焦炭的CRI和CSR及CRI-PRTP的实验研究和分析显示,几种焦炭的反应初始温度有较大差别,最大相差44℃. 焦炭D的CSR为74.1,但较高的CSR主要是其低CRI造成的,用等溶损率后强度能够更好地评定焦炭抵抗溶损劣化的能力. 焦炭A的溶损-热处理后与等溶损率后强度相比,降低幅度达到了7.1%. 研究证明,用CRI-PRTP评定焦炭热性质可行.     

焦炭反应性与反应后强度的关系及其影响因素探讨

为了很好地预测焦炭在高炉中的反应行为,对大量的焦炭进行了检测及数据的分析,说明焦炭反应性与反应后强度之间有良好的负相关性;对焦炭冷态强度与热态性能之间进行了对比,建议焦化企业在保证焦炭的冷态强度合格的同时,更要关注焦炭的热态性能指标;对影响焦炭反应性与反应后强度的反应温度、碱金属、钝化剂等因素进行了试验,指出在生产中应严格控制高炉操作温度,并在按国标方法测定时,加入一定浓度的碱类,以模拟高炉生产的实际过程。提出熄焦时采用一定浓度的硼砂溶液喷洒焦炭,可改善焦炭的热性能。     

碱土金属Ca的添加方式对焦炭溶损反应的影响

采用前置法和后置法制备添加碱土金属Ca的焦炭.考察不同反应温度下,CO_2对焦炭溶损行为的影响,并运用比表面积测定仪、X射线衍射仪和扫描电子显微镜表征焦炭的微观结构.结果表明:添加碱土金属Ca可以提高焦炭的反应性.当温度达到1 200℃时,后置法焦炭的反应性和反应后强度均高于前置法焦炭的反应性和反应后强度.用随机孔模型模拟了焦炭溶损反应动力学过程,后置法制备的焦炭溶损反应活化能较前置法制备的焦炭溶损反应活化能低.添加碱土金属后的焦炭微晶结构有序性、微晶尺寸和反应前后的比表面积均发生变化.     

捣固焦与顶装焦在高炉内行为的对比分析

从密度、气孔率、反应性和微观结构等方面对捣固焦和顶装焦进行对比分析可知,捣固焦具有较高的显密度和显气孔率;碱金属对焦炭溶损反应起催化作用,碱金属对捣固焦的催化作用大于顶装焦。     

影响焦炭热态性质的因素探讨

对皖北17种煤样进行了性质分析及40kg小焦炉炼焦试验,结果表明,灰分中的碱性氧化物对焦炭的溶损反应起着正催化作用,其含量越大,焦炭的反应性越大;挥发分含量在20%～24%、镜质组反射率在1.3～1.8之间的煤,焦炭的反应性和反应后强度较好;硫的存在能抑制焦炭的CO2反应性,随着硫含量的增高,焦炭的反应后强度有所提高.建立的预测模型具有一定的可靠性与稳定性.     

氧化铁对焦炭溶损反应的影响

在井式硅钼棒电炉中对焦炭溶损反应性进行研究,考察了反应条件(CO₂流量、反应时间)并重点研究负载氧化铁对焦炭溶损反应性的影响;通过扫描电子显微镜(SEM)和电子能谱(EDS)对反应前后负载氧化铁的焦炭进行分析,探究氧化铁负载方式对焦炭溶损反应影响差异的原因,并进一步分析比较其影响机理。结果表明:焦炭溶损反应性随CO₂流量和反应时间的增加而增大;以吸附法和添加法负载氧化铁对焦炭溶损反应均有促进作用,氧化铁吸附负载量存在一个饱和点(1%),超过该点后氧化铁吸附负载量对焦炭溶损反应性影响甚微;吸附法负载氧化铁对焦炭溶损反应性的影响大于添加法。SEM分析表明:添加法的部分铁氧化物被焦炭气孔壁基质包裹而无法发挥作用,吸附法的氧化铁均匀分布在焦炭表面使其能提供更多有效催化活性中心;且添加氧化铁时铁氧化物参与成焦,影响焦炭结构从而对焦炭溶损反应产生影响,吸附氧化铁则是影响焦炭溶损反应的催化作用,两种负载方式下氧化铁的影响机理不同。     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

几种针状焦性能对比

针状焦分石油系和煤系两大类,这主要取决于针状焦的原料来源。在同一系列中由于原料不同和工艺条件不同 ,针状焦的各自性能也不相同。针状焦是生产超高功率石墨电极和高功率石墨电极的主要原料 ,针状焦的性能对石墨电极的质量有至关重要的影响。所以对针状焦性能以及其对石墨电极质量影响的研究十分必要的。以下是常用的几种进口针状焦和国产针状焦的性能对比。１原料性能分析对比原料试样包括４种针状焦 ,其中两种为进口针状焦：三菱针状焦和新日化针状焦;另两种为国产针状焦：鞍山针状焦和锦州针状焦。其中除锦州针状焦是石油系针状焦外…     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。