双腔齿辊式破碎机改为环锤破碎机的实践

在破碎设备中,有多种破碎机,有不同的优缺点,应根据锅炉类型选择合适的破碎设备。针对原双腔齿辊破碎机不能满足设计要求、维护成本高的事实,在大修期间将齿辊破碎机改造成环锤式破碎机,结果表明,该设备运行稳定,功耗极大降低,破碎机维护和备件更换成本极大降低,卸料粒度减小,达到了很好的改造效果。     

自制块煤破碎机的粉尘回收装置

1概况 烧煤粉的锅炉，燃料煤一般经两级破碎。第一级是粗破碎，把粒度大的煤块破碎成小于30mm的煤块；第二级是磨粉，把燃煤磨成粉状，然后鼓风吹进锅炉燃烧室进行燃烧。     

细环锤式破碎机改造

1问题的提出 山东恒通化工股份有限公司热电厂输煤系统采用一级破碎装置——细环锤式破碎机。在正常情况下，2套输煤系统1开1备，上煤量和上煤颗粒度完全满足循环流化床锅炉的需要。自从2003年下半年以来，进厂煤质量较差，煤中矸石杂质较多，细环锤式破碎机的出料粒度不理想，部分入炉煤颗粒度过大，不仅加重了锅炉受热面磨损，还容易造成燃烧不充分，容易结焦和堵塞冷渣器冷渣通道，严重影响了锅炉机组的正常运行。     

燃料破碎—干燥—气力分选系统及其在褐煤蜡生产中的应用

<正> 目前,国内在制备颗粒煤(粒径≤8mm)的系统中多采用常规机械破碎筛分方式。主要设备为反击式破碎机和振动筛。实验表明,这样的系统存在以下问题: (1)机械筛分装置运行不可靠,受力部件易断裂、脱焊; (2)筛网磨损较严重。筛网损坏后常使大粒径煤块漏网,因此难以连续稳定地供应粒度合格(一般要求≤8mm)的颗粒煤; (3)燃料表面水分较高时,湿煤易粘附在振动筛网表面、破碎机击板及系统各部,严重影响着系统出力和运行; (4)破碎机板锤及反击板磨损钢耗较高;     

辊式筛分给料机在砂岩破碎系统中的应用

原砂岩破碎系统采用颚式破碎机加圆锥破碎机组合方式，在对大块砂岩破碎时，砂岩中含细料、沙土，水分大时，经常发生堵圆锥破碎机的情况，严重影响砂岩破碎系统的台时产量和砂岩破碎系统的正常运行。在物料进圆锥破碎机之前增加辊式筛分给料机，将符合粒度要求的物料筛出，以减轻圆锥破碎机的负荷，并避免水分大的物料堵塞圆锥破碎机，提高砂岩破碎系统的稳定性。     

循环流化床锅炉输运系统设计

介绍了燃料制备及冷却除渣系统 ,该系统为循环流化床锅炉提供了合格的燃料并连续自动地排除灰渣 ,确保了锅炉安全稳定的运行     

煤破碎工艺的改进

我厂煤的破碎是一台PETh500ｘ400颚式破碎机，最大进料粒度为210mm，出料口凋节范围20—80mm，生产能力为5～20t／h，其工艺布置如图1所示。煤破碎存在的主要问题是：煤的水分大或有杂物时，破碎机会发生堵塞；当煤中存在大块时，破碎机可能被卡死，大块煤卡在破碎口下不去；为     

筛分布料一体破碎机在循环流化床锅炉碎煤的应用

分析了循环流化床锅炉对燃煤粒度的要求,介绍了目前市场上各主流破碎机的结构特点、工作原理、主要优缺点等,结合具体项目燃煤筛分破碎系统的设计方案,阐述了筛分布料一体破碎机的技术特点及优势,认为该设备满足了循环流化床锅炉进煤粒度均匀且系统不堵煤、运行稳定的要求。     

硅破碎技术的比较研究

介绍了料层破碎和单颗粒破碎工艺，比较了颚式破碎机和反击破碎机的技术性能和实践效果，认为在硅制粉现行工艺上，反击破碎机的粉碎效果优于颚式破碎机。     

应用层压理论设计高效PC破碎机

针对国内破碎产品粒度偏大，严重影响磨机处理能力的问题，用生产实例说明，应用层压理论研制的PC破碎机不仅能降低破碎产品粒度、提高磨机的处理能力，而且还能减少电耗、降低成本和增加效益。简述了层压理论的原理；介绍了PC破碎机的设计原理、结构特点及优点技术性能优良的PC破碎机，已成为众多厂矿为实现“多辞少磨”目标而选用的理想破碎机。     

鼓泡破泡一体化高效精馏塔盘流动特性与CFD模拟

就痕量精馏中塔板传质效率低、需强化气液传质的问题,研究者提出了新型鼓泡破泡一体化高效精馏塔盘,通过在筛板上泡沫层高度范围内设置一层破泡装置,打破大气泡,减小气泡体积,强制界面进行更新,从而提高传质效率。采用双欧拉模型分别对鼓泡破泡一体化塔盘和筛板进行了气液流场的数值模拟,并对模型进行了验证。对比两种塔板的计算结果可以看出：在相同操作条件下,破泡装置将大气泡破裂成无数小气泡,使高气含率区域面积较普通筛板进一步增大,且气含率梯度变化更均匀;增加破泡装置后,在相同气速条件下气泡上升速度下降,气体在液层中的滞留时间延长,使鼓泡层高度增加,可显著提高传质效率,且降低了气体雾沫夹带量;破泡装置还明显改善了气相的纵向分布,气含率由塔板底部向上逐渐增大且存在明显分界;破泡装置附近湍动较剧烈,气泡破碎喷出的气体会进一步撕裂液膜,气体破碎作用会抑制气泡聚并,促进界面的快速更新更有利于传质过程的进行。研究结果可对工业塔板设计和优化提供指导。     

A novel technique for particle tracking in cold 2-dimensional fluidized beds—simulating fuel dispersion

This paper presents a novel technique for particle tracking in 2-dimensional fluidized beds operated under ambient conditions. The method is applied to study the mixing mechanisms of fuel particles in fluidized beds and is based on tracking a phosphorescent tracer particle by means of video recording with subsequent digital image analysis. From this, concentration, velocity and dispersion fields of the tracer particle can be obtained with high accuracy. Although the method is restricted to 2-dimensional, it can be applied under flow conditions qualitatively resembling a fluidized-bed combustor. Thus, the experiments cover ranges of bed heights, gas velocities and fuel-to-bed material density and size ratios typical for fluidized-bed combustors. Also, several fluidization regimes (bubbling, turbulent, circulating and pneumatic) are included in the runs.A pattern found in all runs is that the mixing pattern of the tracer (fuel) solids is structured in horizontally aligned vortexes induced by the bubble flow. The main bubble paths always give a low concentration of tracer solids and with the tracer moving upwards, while the downflow of tracer particles in the dense bottom bed is found to take place in zones with low bubble density and at the sidewalls. The amount of bed material (bed height) has a strong influence on the bottom bed dynamics (development and coalescence of bubbles) and, consequently, on the solids mixing process. Local dispersion coefficients reach maximum values around the locations of bubble eruptions, while, in the presence of a dense bottom bed, an increase in fluidization velocity or amount of bed material enhances dispersion. Dispersion is found to be larger in the vertical than in the horizontal direction, confirming the critical character of lateral fuel dispersion in fluidized-bed combustors of large cross section.     

The role of fuel reactivity in fluidized-bed combustion

This paper reports the use of the two-phase bubbling fluidized-bed model for calculations of the conditions in fluidized-bed combustors. The model takes account of the sequential steps of oxygen transport from bubble to dense phases, transport through the dense phase, and finally reaction with the fuel particle. At 1200 K, for practical conditions of pressure, fluidizing velocity, particle size, bed voidage and bubble size, fuel reactivity was sufficiently high, and bubble-to-dense phase transport sufficiently rapid, to ensure that neither of these steps had a notable rate-controlling effect. Transport through the dense phase was of most influence. However, some effect of reactivity was shown at 1000 K, and a strong effect occurred at 800 K. The model proved to be markedly sensitive to the carbon concentration in the bed, bubble size, and particle size.     

流化床-化学气相沉积技术在先进核燃料制备中的应用进展

流化床-化学气相沉积（FB-CVD）技术是化工流化床技术和材料化学气相沉积制备技术的交叉耦合,兼有流化床处理量大、传热快、温度均匀以及化学气相沉积温度调节范围广、产物丰富多样等优点,其在先进核燃料制备中有着重要的应用,但随着先进核燃料“质”和“量”的不断发展要求,现有的FB-CVD技术有许多方面亟待完善。本文回顾了作者课题组利用流化床-化学气相沉积在高温气冷堆TRISO核燃料颗粒、先进核燃料包覆颗粒、核燃料示踪颗粒、基体SiC纳米颗粒、SiC@Al₂O₃复合纳米颗粒等方面的研究进展,阐述了基本方法、实验过程和典型研究结果,并分析了流化床-化学气相沉积过程中遇到的实际问题。指出了FB-CVD技术未来发展方向,主要涉及反应器规模化放大和连续性生产、孔口沉积消除及温区控制、粉体制备中的纳米颗粒连续收集、新型反应器及工艺设计等方面,具体包括高密度颗粒稳定流化放大准则、床层局部温区控制以及分区流化床结构设计等。     

Single bubble eruptions in gas fluidized beds

The motion of the solids thrown above the bed surface by single bubble eruptions was studied using a high speed video system. Data on the motion of the bubble and emulsion phases are presented as functions of bubble size, type of bed material, fluidizing velocity and bed depth. When plotted in dimensionless form, the trajectories of the tops of the bulge layer, bubble and wake can be condensed into three universal curves which represent the trajectories for these points for the entire range of bed materials, bubble sizes, fluidization velocities and bed depths tested. There appeared to be no significant effect of excess air, bubble size or bed depth on the dimensionless heights reached by the wake and bulge materials. In all cases the bulge material was ejected to a greater height above the bed than the wake.     

流化床中气泡的汇合长大和床层膨胀

根据文中提出的沿单位床层高度气泡平均直径的长大与气泡在水平面内的平均分开程度成比例的简化模型和已有的大量实验数据,获得了气泡沿床高长大的计算方程 本文还根据两相邻生成的初始气泡的垂直中心距与初始气泡直径成正比的简化模型及已有的实验数据,提出了初始气泡直径D_B_0的计算方程 基于上述获得的方程式以及假定鼓泡流化床的床层膨胀纯因气泡存在所造成,本文还导得了自由鼓泡流化床膨胀高度的计算式     

Assessment of gas-particle flow models for pseudo-2D fluidized bed applications

The aim of this work is to provide more insight into the general modeling criteria for simulating pseudo-2D bubbling fluidized beds. For this purpose, two experimental-based problems are studied. First, a fluidized bed with a high-speed central jet problem is analyzed. A qualitative study of the first bubble indicates that the bubble shape prediction is highly sensitive to the frictional model adopted. The most accurate results in terms of bubble shape and detachment time are given by a frictional model that relates the strain-rate fluctuations with the granular temperature. Second, a uniformly fluidized bed problem in bubbling regime is considered. For this case, the drag models and boundary conditions for the particulate phase are investigated. Time-averaged solid phase velocity profiles are compared with the results of the literature where it is found that no-slip conditions (or partial slip with a high specularity coefficient) are more appropriate than slip conditions at the walls for these regimes. Regarding the drag force, although none of the models presented could match the experimental velocity predictions for low gas velocities at the lower region of the bed, the Di Felice model produces the most accurate results for the whole range of regimes considered.     

气泡在颗粒床层表面的生成脱离行为

试验研究了气泡在颗粒床层表面的生成脱离过程及其行为特性,利用高速摄像技术揭示了进气管管径、颗粒床层高度、颗粒粒径等因素对气泡脱离直径及其生成周期的影响规律,对比分析了颗粒床层表面和进气管管口的气泡生成脱离行为差异。研究结果表明：在1500～3000μm粒径范围的床层表面所生成气泡的初始形态相对更扁小,气泡也更快向扁平状演变;颗粒粒径的增大使得进气流量对气泡形态的影响减弱;管径和颗粒床层高度的增大可以有效促进气泡脱离直径的增长,但延缓了气泡的生成脱离,增加了气泡的生成周期;颗粒粒径对气泡生成周期的影响随着进气流量的增大而逐渐减弱;气泡在颗粒床层表面和管口的生成脱离行为存在显著差异,相比之下,150～300μm粒径范围的颗粒床层对气泡的生成脱离具有更明显的阻碍作用,其表面所生成气泡的脱离直径和生成周期相对较大。     

MODEL FOR PREDICTING THE LATERAL DISPERSION COEFFICIENT OF SOLIDS IN GAS-SOLIDS FLUIDIZED BEDS

The lateral mixing of solids in a gas-solids fluidized bed is very complicated.It can be caused by:(a)bubble movement through the bed,(b)bubble burst at the bed surface,and(c)gross particle circulation in thebed.However,experiments show that the major factors effected the lateral mixing of solids are the bubblemovement through the bed and the bubble burst at the bed surface.Thus a model with two mixing re-gions,i.e.mixing in bubble rising region and mixing in bubble breaking region,was proposed.Based on thismodel,an equation for predicting the lateral dispersion coefficient of solids in gas-solids fluidized beds wasderived without any adjustable parameter.The calculated values by this equation are well comparable withthe observed data including the present work and the other investigations.