Hydrodynamics of shallow,conical spouted beds

Experiments were conducted with shallow beds, in the presence of atomizing air injected into the base, under the following conditions: Particles — urea, sulphur coated urea, polyethylene, polyformaldehyde and polystyrene; particle diameters (d_p) – 2.1 to 2.8 mm; cone angle – 60°; cylindrical bed diameter (D) – 0.24 and 0.45 m; bed height (H) – 0.24 to 0.40 m; orifice diameter (d_i) – 21 to 35 mm; main spouting air (Q_s) ≤ 37 L(actual)/s; atomizing air (Q_a) ≤ 0.87 L(actual)/s. The minimum spouting velocity is well represented by: U_ms = 13.5 (2gH)^0.5 (d_p/D')^1.17 (D'_i/D')^0.372 (H/D')^?0.148 [(τ_p - τ)/τ]^0.289 where D' and D'_i denote the modified column and orifice diameter, respectively. Q_a, which affects D'_i, significantly influenced the air velocity in the spout, but not the pressure profiles in the annulus. Morgan and Littman's (1980) correlation could be adapted to predict the experimental pressure profiles in the annulus.     

两种煤气化方式的比较

对两种气化工艺(Lurgi和GSP)从气化方法、煤种、进料要求、气化炉构造及国产化、生产能力、气化炉开车、废水处理方面进行了比较。通过比较,GSP气化比Lurgi气化具有气化煤种更广泛、煤种适应性更强、气化炉构造简单、维修量小、生产能力大、开车快、废水量少且处理系统简单的优点,Lurgi气化比GSP气化具有简单的进料要求、高的设备国产化率、低的氧气消耗、运行业绩较多的优点。为选择气化方式时提供参考。     

典型煤气化技术概述

我国煤炭资源丰富,能源消费以煤炭为主。煤炭气化是煤高效洁净利用的关键技术。分别对固定床、流化床及气流床气化工艺进行了简介,列举了典型的煤气化技术,分析了各自的工艺特点,并对其应用现状进行了综述。     

SOME ASPECTS OF THEORETICAL COMPARISON OF FISCHER-TROPSCH REACTORS

The reactor systems used for the Fischer-Tropsch synthesis, fixed bed, fluidized bed and slurry bed, are compared on the basis of space time yield (STY) and level of conversion obtainable under the same set of feed and operating conditions. The slurry bed and fluidized bed reactor were compared on the basis of a first order reaction model. The performance of these two reactors was found to be comparable at low values of WHSV, but at higher values of WHSV, the fluidized bed reactor gave higher conversions and STY. A power law kinetic expression was used to compare the performance of the slurry bed and fixed bed reactors. Higher conversions and STY were obtained from the fixed bed with varying WHSV. This may be due to the omission of the intra and inter phase mass transfer resistances in the modelling of the fixed bed reactor.     

3万t/a苯胺流化床反应器的设计

介绍了3万t/a苯胺流化床反应器整体结构,重点介绍了设备直径、高度的确定,内构件设计和分离段旋风分离器的设计,此设备已成功应用到生产中并稳定运行多年。     

各类煤气化炉的特点与适应性分析

分析综述了已经实现工业化生产的各类煤气化炉的特点,煤种适应性,各自的煤气质量和应用领域,工业化放大的不同特点,气化效率的不同,对环境的不同影响等。可为计划上马煤化工项目的用户选择气化技术提供参考。     

国外渣油加氢技术研究进展

随着原油劣质化趋势的加剧及环保法规的日益严格,渣油加氢技术已成为炼厂提高轻油收率的关键技术。本文针对目前主要的渣油加氢技术,比较了固定床、沸腾床、悬浮床、移动床四大类型渣油加氢技术的优势和不足,重点分析了国外主要的渣油加氢技术的研究进展,探讨了未来的发展趋势。固定床加氢技术最成熟,在可预见的未来仍将占据渣油加氢的主导地位;沸腾床加氢技术日趋成熟,代表未来渣油加氢的发展方向;移动床加氢技术暂不作为渣油加氢的有效手段;悬浮床加氢技术尚未实现工业化应用,正在建设多套工业装置,具有良好的发展前景。渣油加氢技术与其他重油加工工艺进行优化集成,将会显著提高炼厂的经济效益。     

费托合成反应器应用研究进展及展望

费托合成反应是强放热的气液固三相反应,为有效移热及提高目标产物产率,应加强费托合成反应器的研发,系统介绍了工业上几种费托合成反应器的特点、应用规模等,论述了近几年已经或有望进行工业化应用的几种费托合成反应器,如固定床反应器、流化床反应器、浆态床反应器等,并比较了各类反应器的优劣,最后对费托合成反应器的选型和发展提出了建议和展望。固定床反应器技术成熟,产品容易分离,催化剂损失少,但是移热效果较差;浆态床反应器,反应物混合均匀,移热效果好,但产品固液分离较为困难;流化床反应器可以在高温下运行,生产高价值的轻烃产物,但催化剂消耗较大。研究认为,如果目标产品是以分子质量较大的柴油和石蜡为主,建议选择浆态床反应器;如果目标产品是生产烯烃等化学品,建议选择固定流化床反应器。     

渣油加氢技术应用现状及发展前景

渣油加氢技术是实现渣油清洁高效转化的关键技术,正逐渐成为炼厂主要的渣油加工技术手段。本文详细介绍了渣油加氢技术在应对石油需求量不断增加、原油重劣质化趋势加剧、环保法规日益严格、加工利用非常规石油资源等诸多挑战方面的重要性和紧迫性;重点分析了渣油固定床加氢处理技术、沸腾床加氢裂化技术和悬浮床加氢裂化技术的发展现状及未来趋势。渣油固定床加氢处理与催化裂化组合技术将是中长期内发展的重点技术,沸腾床加氢裂化技术需解决装置投资大、操作复杂等问题,悬浮床加氢裂化技术具有独特的优势,推广应用前景看好。     

The internally circulating fluidized bed (ICFB): A novel solution to gas bypassing in spouted beds

The bypassing of a portion of the inlet spout gas to the annular region of spouted and spout-fluid beds can have a critical effect on processes requiring accurate control of the spout gas residence time even when a draft tube is utilized. A modification to the spout-fluid bed with draft tube called the Internally Circulating Fluidized Bed or ICFB is proposed which eliminates this bypassing problem. Experiments were conducted on a cold 20 cm diameter semi-cylindrical unit to define the operational characteristics of the ICFB with particular emphasis on the gas and solids flow behavior. The solids and gas flow rates in the unit were successfully related by a published correlation which was developed for the cocurrent flow of gases and solids through orifices.     

海藻生物质颗粒流化床燃烧试验研究

在小型流化床试验台上研究了海藻颗粒(条浒苔与马尾藻)的流化床燃烧。海藻在流化床内的挥发分析出燃烧时间都在1 min左右。条浒苔颗粒在流化床中燃烧先进行脱水和挥发分的燃烧,接着发生焦炭燃烧,其燃烧过程符合缩核模型,炭核由外向内逐层燃烧,而灰层半径几乎不变。但马尾藻颗粒由于挥发分的大量快速释放而迅速膨胀破碎成屑。另外通过对条浒苔颗粒及不同燃烧时间后收集的焦炭颗粒剖面的SEM扫描电镜观察,发现随着燃烧的进行,颗粒内孔隙增大,微孔表面粗糙。进一步详细研究了两种海藻颗粒(条浒苔与马尾藻)在流化床内单次投料下的燃烧。随着床温的升高,条浒苔释放NO_x相对浓度增加,CO相对浓度减少。而马尾藻释放气体中SO₂与NO_x含量相对条浒苔有所增加;随着床温的升高,CO相对浓度减少。床温的升高使得床内传热速率加快,两种海藻挥发分的析出提前,燃尽时间缩短。风速、床高的升高使得两种海藻燃烧容易,燃尽时间缩短。     

The heat transfer coefficient between a particle and a bed (packed or fluidised) of much larger particles

The heat transfer coefficient has been measured for a heated phosphor-bronze sphere (diam. 2.0, 3.0 or 5.56 mm) added to a bed of larger particles, through which air at room temperature was passed. The bronze heat transfer sphere was attached to a very thin, flexible thermocouple and was heated in a flame to before being immersed in the bed. The cooling of the bronze sphere enabled the heat transfer coefficient, h, to be measured for a variety of U/U_mf, as well as diameters of both the particles in the bed and the heat transfer sphere. It was found that before the onset of fluidisation, h rose with U, but h reached a constant value for U?U_mf. These measurements indicate that in this situation (of a relatively small particle in a bed of larger particles) all the heat transfer is between the hot bronze sphere and the gas flowing over it. Consequently, a Nusselt number, based on the thermal conductivity of the gas, is easy to define and for U?U_mf (i.e. a packed bed), Nu is given by

     

Study of the Drying Kinetics in Thin Layer: Fixed and Moving Bed

Abstract

Drying kinetics of soybean seeds were investigated in the fixed bed (which is normally used) and in the moving bed with cross flow, both being run under thin-layer conditions. The analysis of the available data followed the diffusive model approach with re-parameterization. Special attention has been given to the nonlinearity inherent in the database in order to evaluate the statistical properties of the least squares estimator. The results showed that the effective diffusivity of the moving bed is 24 to 44% higher than that of the fixed bed.     

Study of the Drying Kinetics in Thin Layer: Fixed and Moving Bed

Drying kinetics of soybean seeds were investigated in the fixed bed (which is normally used) and in the moving bed with cross flow, both being run under thin-layer conditions. The analysis of the available data followed the diffusive model approach with re-parameterization. Special attention has been given to the nonlinearity inherent in the database in order to evaluate the statistical properties of the least squares estimator. The results showed that the effective diffusivity of the moving bed is 24 to 44% higher than that of the fixed bed.     

Fluid dynamics of a fluidized-moving bed (flumov)

The fluid dynamics and other features of a gas-solid contactor based on a combination of FLUidized and MOVing beds (flumov) were studied. The fluidized zone is below the moving one; the mov/flu diameter ratio ranges between 2 and 3. The two zones are joined by means of a conical part and no mechanical elements are used between the bottom of the moving bed and the top of the fluidized bed. The gas is fed at the bottom of the fluidized bed; the solid is fed at the top of the moving bed and, consequently, it moves in countercurrent to the gas and in a continuous mode. The adequate regime is reached when a stable vault between the bottom of the moving bed and the top of the fluidized bed is formed and maintained. The solid circulation from the moving to the fluidized bed is controlled by injecting air pulses from the bottom of the moving bed, at different points of the conical zone. The study comprises the influence of both the contactor geometry and the solid type on the pressure drop profiles and the general flumov performance. The angle of the conical device joining the two zones is an important geometrical parameter and, in the range studied, the flumov performance does not depend on the tested solid size and type.     

Improved design and optimization models for the fixed bed adsorption of acid dye and zinc ions from effluents

The bed depth service time (BDST) design model, which accounts for the change of bed adsorption capacity with service time, has been modified to expand its application and overcome the limiting assumptions of the original BDST analysis. Column experiments were undertaken to test the new model for two adsorption systems, namely zinc ion–bone char and Acid Blue 80 dye‐activated carbon. It was found that the percentage of saturation capacity could be correlated using a square‐root dependence on the service time and this correlation was incorporated into the original BDST analysis to replace the total sorption capacity term, giving the model a much wider application to real systems. The empty bed residence time optimization approach was modified using the same time‐dependent capacity expression and was successfully applied to the metal ion–bone char and the dye‐activated carbon system with the use of equilibrium saturated bed capacity. These modifications to the BDST design model and the EBRT optimization model will give more accurate scale‐up data for the design of large‐scale column adsorption systems. © 2002 Society of Chemical Industry     

A general model for pressure drop prediction across a rotating packed bed

Although rotating beds show promise for intensified separations, the fundamentals of their hydrodynamics are still poorly understood. In many operating conditions, pressure drop in an irrigated bed can be considerably lower than that across a dry bed. Previously published correlations don’t provide good prediction of these phenomena. In this research, a semi-empirical correlation is developed to predict the pressure drop across the rotating packed beds. The results show the agreement of predicted pressure drop with the experimental data is acceptable. This model can also predict the pressure drop unexpected phenomena of higher pressure drop in dry beds than in wet beds.     

氧化还原树脂去除脱盐水溶解氧的试验

采用凝胶型阴、阳离子氧化还原树脂和大孔型阴、阳离子氧化还原树脂对去除脱盐水中的溶解氧进行了试验。结果表明:在不同温度和流化床、顺流床、浮动床3种运行方式下,脱盐水分别通过凝胶型氧化还原阳离子交换树脂和大孔氧化还原阳离子交换树脂后,其含氧量均不超过20μg/L,符合发电机内冷水的用水要求;脱盐水通过2种氧化还原阴离子交换树脂后其含氧量均超过60μg/L,不宜用作除氧树脂。     

加压热煤气脱硫工艺研究

介绍了加压热煤气脱硫“北京煤化－ＳＭＯＶＥＮ”工艺以及工艺研究试验的主要结果。热煤气脱硫小型连续试验装置投入稳定运行，取得了较好的结果，试验验证了ＳＭＯＶＥＮ工艺的技术合理性和操作可行性，为其工艺放大研究打下良好基础。     

浅谈煤气化技术进展及选择

阐述了研究和开发煤气化技术的重要意义，详细介绍了目前国内外主流煤气化技术的进展及应用，比较了各种煤气化技术的优缺点，并对如何选择煤气化技术提出了自己的看法。