Effect of particle size on lignite devolatilization in a fixed-bed reactor

A fixed-bed coal gasification reactor was set up which specifically simulated the devolatilization zone in a gasifier. Samples (100 g) of lignite coal in three size ranges; ?2+1 mm, ?3+2 mm and ?4+3 mm, were devolatilized in the temperature range 350–550 °C with a steam-oxygen mixture, at 1 atm. The effect of these operating variables on tar yield and composition, melting point, viscosity, specific gravity, and molecular weight distribution was determined. A first-order reaction model was fitted to the experimentally observed total loss in weight of the lignite.     

Kinetics and reaction mechanism of catalytic oxidation of low concentrations of hydrogen sulfide in natural gas over activated carbon

The kinetics of the hydrogen sulfide oxidation process, producing mostly sulfur and water, was studied using 0.25 to 1.0 g Hydrodarco activated carbon catalyst and varying the O₂/H₂S ratio (molar basis) in the feed gas between 0.5 to 0.6 in the temperature, and pressure ranges from 125 to 200°C and 225 to 780 kPa. SO₂ was obtained as an undesirable by-product during H₂S oxidation reaction or as a product during regeneration of the catalyst. The feed gas contained 0.9 — 1.3 mol% H₂S with approximately 80 mol% CH_4. In this paper, the factors affecting the H₂S conversion and SO₂ formation are presented. The rate expressions for (a) H₂S conversion and (b) SO₂ formation were developed from the Langmuir-Hinshelwood surface control reaction model. The experimental data were well correlated by the rate equations. Also, the rate parameters were evaluated and correlated with temperature. The activation energies for H₂S oxidation and SO₂ production reactions were calculated to be 34.2 and 62.5 kJ/mol, respectively. Partial pressures of oxygen and H₂S were found to influence H₂S conversion whereas, the presence of water in the feed gas up to 10.5 mol% did not affect H₂S conversion significantly. Heats of adsorption for various species on the active sites were calculated. SO₂ production was, as expected, enhanced at higher temperature, and its rate was much smaller than the oxidation rate of H₂S under the reaction conditions used.     

块煤焦固定层造气中氮改小氮流程的实践

中氮改小氮是当前的热点，改造后的实际效果却从未见到过有说服力的报道。本文对我公司造气系统中氮改小氮流程的实践进行了定性和定量评价，意为未改者提供改造依据，为已改者提供进一步完善的思路。     

液固体系固定床吸附器流出曲线预测模型──活性炭吸附水中酚的研究

建立了液固体系的固定床吸附预测模型,并用正交配置法获得了模型方程的数值解,实验测定了苯酚在活性炭上的静态和动态吸附数据,采用Marquadt法优化固定床吸附流出曲线数据,得到了不同浓度条件下的表面扩散系数及其变化规律,并据此预测了其他操作条件下的穿透曲线,预测曲线与实验结果相符甚好．     

Comparative Evaluation of Nanoporous Hydrocracking Catalysts in Fixed-Bed and Swing-Batch Reaction Systems

Abstract

A comparison of the results using Ni-W and Ni-Mo loaded catalysts with desulfurized vacuum gas oil shows that both the fixed-bed reaction and swing-batch reaction systems can be used efficiently for the catalysts evaluation. The results from a fixed-bed reaction showed that Cat-2 catalyst was more active than both Cat-1 and Cat-3, while the hydrodesulfurization (HDS) activity of Cat-3 catalyst was slightly better than that of Cat-1 and Cat-2. In the swing-batch reaction, Cat-1 and Cat-2 showed higher activity as compared to Cat-3 and Cat-4 catalysts. NiW loaded catalysts were found more active than NiMo loaded catalysts. HDS and cracking activities in the swing-batch reactor were found lower as compared to the fixed-bed reactor, probably due to recombination reactions involving sulfur and other cracked molecules.     

固定床“一步法”连续合成对乙酰氨基酚的研究

:采用钯炭颗粒催化剂 ,研究了固定床“一步法”连续合成对乙酰氨基酚的工艺条件。在催化剂重 0 .50 g,对硝基酚质量分数 5.0 % ,醋酐与对硝基酚的摩尔比为 1 .2～ 1 .4,液时空速 0 .50～ 3.0 0 /h,氢压 1 .0～ 1 .4MPa,反应温度 1 60～ 1 80°C等条件下 ,对硝基酚转化率 1 0 0 % ,成品对乙酰氨基酚选择性达 95.0 %以上。     

丙烯醇催化氨化合成3-甲基吡啶催化剂的制备及性能

采用浸渍法制备了一系列H-ZSM-5分子筛负载过渡金属锌催化剂,在固定床反应器上考察了这些催化剂对丙烯醇催化氨化合成3-甲基吡啶的催化性能。通过对H-ZSM-5的硅铝比、锌负载量对催化剂催化性能影响的考察,发现硅铝比为80、锌负载量为12%时得到的催化剂Zn₁₂/H-ZSM-5（80）的催化性能最佳。在常压、反应温度420℃、氨醇摩尔比3：1、空速300 h^-1条件下,丙烯醇在该催化剂上的转化率和3-甲基吡啶的选择性分别达到97.8%和37.9%。利用X射线衍射（XRD）、X射线光电子能谱（XPS）以及吡啶吸附红外对催化剂进行了表征,结果表明,Zn₁₂/H-ZSM-5（80）上负载的Zn²⁺为L酸;在丙烯醇生成3-甲基吡啶的反应过程中催化剂的脱氢活性物种为氧化锌,而加成和环合反应则主要是由催化剂中的L酸催化实现的。     

不同温度区间内污泥热解气固相产物特征

对城市污水污泥（简称污泥）进行工业分析和热重分析,考察污泥的基本组成和热重特性;采用气相色谱（GC）检测了不同热解温度区间内污泥热解生成的气体产物成分,并利用SEM和BET分别分析了不同热解终温下裂解炭的形貌特征和比表面积。结果表明：污泥热解可以分为水分析出阶段、挥发分析出阶段和焦炭化阶段;不同热解温度区间内污泥热解气体产物的组成有很大差别,热解温度350℃后H₂在热解气中的含量快速增加,CH₄含量在350～450℃时达到最大值,而CO主要在热解温度为350～750℃时生成,CO₂含量随着热解温度的增加迅速下降;随着热解终温的不断升高,裂解炭结构变得越来越疏松,比表面积也随之增大,750℃达到最大值55 m²·g^-1。     

甲缩醛氧化制甲醛固定床单管试验

在固定床单管反应器内进行了甲缩醛氧化制甲醛的试验研究，在接近工业规模反应操作条件下，获得了８８％左右的甲醛收率。为确定工业化流程、工艺操作条件、建立数学模型和进行放大设计提供了依据。     

混合无烟煤固定床常压空气气化特性

分析了朝鲜两种无烟煤及其混合煤的煤质特性,在内径100 mm固定床中进行了3种不同空气鼓风强度的常压气化特性试验,总结出朝鲜混合煤的常压固定床气化特性。