大型合成氨第一废热锅炉逆循环分析

针对合成氨装置凯洛格流程中第一废热锅炉可能产生逆循环的情况,对锅炉水循环原理及循环判断进行详细的分析,并提出生产中避免产生逆循环的操作要点,以便进一步指导工艺操作。     

大型合成氨装置第一废热锅炉逆循环分析

针对合成氨装置凯洛格流程中第一废热锅炉可能产生逆循环的情况,对锅炉水循环原理及循环判断进行详细地分析,并提出避免产生逆循环的操作要点。     

刺刀式废热锅炉逆循环的原因与措施

探讨刺刀式废热锅炉逆循环的原因,提出相应的解决措施。     

导致循环流化床锅炉高温结焦的原因与处理措施分析

在社会经济飞速发展的今天，循环流化床锅炉在很短时间内发展迅速，这是因为它具有一系列的优势，比如效率很高，污染较低等等。但是通过长期的实践研究发现，在新型循环流化床锅炉运行过程中，会出现结焦的事故，需要引起人们的重视。本文简要介绍了循环流化床锅炉高温结焦产生的原因，然后结合这些原因提出了相应的处理预防措施，希望可以提供一些有价值的参考意见。     

35t／h煤粉锅炉改循环流化床锅炉的研究

介绍了一台35t/h煤粉锅炉改循环流化床锅炉的设计与运行。改造后的循环流化床锅炉不能达到40t/h的额定蒸发量，而且操作性能稳定、煤种适应性广、负荷调节范围大，达到了节能降耗和降低生产成本的目的。     

循环流化床锅炉结焦原因、处理对策及防护措施

随着我国工业的不断发展,对循环流床锅炉的使用越来越多,其具有燃烧效率高、操作方便的优点。在循环流化床锅炉的使用过程中,经常会发生锅炉结焦的现象,不仅影响锅炉的燃烧效率,还降低了锅炉的使用寿命,容易让锅炉发生各种故障。     

循环流化床锅炉安装检修质量对部件磨损的影响以及应对措施探讨

电厂生产过程中锅炉的安全性十分关键,尤其循环流化床锅炉在使用中由于锅炉内燃料粒径不能满足要求,造成内部水冷壁等部件出现磨损现象,从而造成锅炉设备的使用寿命受到影响。对循环流化床锅炉安装检修质量进行分析,提出造成部件磨损现象产生的成因,针对性的提出应对策略,有助于提高循环流化床锅炉在电厂的高效稳定的运行。     

循环流化床内固体颗粒对受热面的磨损及降磨措施

<正> 一、概述循环流化床锅炉中,固体颗粒对受热面的磨损是一个十分重要的问题。目前国外投运的循环流化床锅炉,由于设计不合理,有些锅炉产生了非常严重的磨损,大大降低了锅炉的运行安全性。因为在高循环倍率的循环流化床锅炉中,特别是在其固体颗粒循环回路中,固体颗粒浓度很高,如果不采取措施,会带来严重的磨损。在对循环流化床锅炉进行研究开发的同时,我们也对循环流化床内的受热面磨损以及防磨措施进行了研究。本文报告的是这方面的部分研究结果。     

煤粉炉和循环流化床锅炉飞灰特性对其汞吸附能力的影响

通过分析两台容量相近的循环流化床锅炉和煤粉锅炉飞灰样品的粒径分布、表面结构特性、未燃尽碳含量、反应性和汞含量，探究两种类型锅炉飞灰特性差异及其与飞灰汞吸附能力的关系。结果表明：循环流化床和煤粉锅炉尾端除尘设备排灰口飞灰汞的含量分别为1584.0 ng/g和503.7 ng/g，其原因与飞灰粒径、未燃尽碳含量和表面特性相关。对于循环流化床锅炉，飞灰中汞含量随其粒径和反应性温度的减小而增加，随未燃尽碳含量增加而增加，且与比表面积和吸附量呈正相关关系。对于煤粉锅炉，粒径为75～53 μm的飞灰对汞吸附能力较强，未燃尽碳含量明显小于循环流化床所产生飞灰的含量，飞灰比表面积随粒径变化不大，由此导致煤粉锅炉除尘设备排灰口所取样品对汞的吸附能力远低于循环流化床锅炉相对应位置飞灰对汞的吸附能力。     

循环流化床锅炉运行控制及故障处理

介绍循环流化床锅炉的点火操作，运行中的温度控制，水冷壁管，省煤器等部位发生磨损的原因和处理方法。     

低流量下等高差自然循环系统倒流现象实验研究

自然循环系统由于具有固有安全性而被广泛应用于核电站中。等高差自然循环系统是一种特殊的系统,其加热段与水箱之间是通过上下水平段连接。在低流量条件下,这类自然循环系统会发生水箱冷水倒流至上水平段的现象,目前对该现象的研究并不常见。对等高度差自然循环系统的上水平段倒流特性进行了可视化实验研究。实验结果表明,上水平段倒流长度随流量的增加而减小,随着加热段出口流体与倒流流体温差的增大而增加。研究发现,上水平段倒流现象主要受加热段出口流体惯性力和与倒流流体形成的浮升力共同影响,并且倒流现象的发生可以通过Richardson数来判定。     

塔板上流型变化对板效率影响的计算传质学

利用能够描述塔板上气液两相错流过程的流体力学模型,建立了同时模拟气液两相流动与传质过程的数学模型;通过对气液两相传质方程和流体力学模型方程的联立求解,计算得到了塔板上液相速度分布和气液两相浓度分布的数值解,考察了气相完全混合和气相部分混合两种条件下塔板上的气液两相浓度分布,同时考察了气相完全混合时流型变化对塔板效率的影响.     

Liquid flow circulating within an unbaffled vessel agitated with an unsteady forward–reverse rotating impeller

Liquid‐phase mixing is a common operation, often performed in vessels using mechanically rotating impellers. To enhance axial mixing the vessels are generally equipped with baffles; however, in industries where cleaning the vessel interior is a major concern, i.e. food and pharmaceuticals, and crystallization, where baffles can disturb particle growth, unbaffled vessels are preferred. One method of agitation in unbaffled vessels is an impeller that periodically changes either the direction or rate of rotation: so‐called unsteady rotation. For use in an enhanced agitation vessel, an agitation technology using an unsteady forward–reverse rotating impeller in an unbaffled vessel was investigated. Such unsteady agitation is expected to enhance mixing. However, knowledge of the liquid flows in such an apparatus remains elusive. Thus an aim of this work was to characterize the circulation flow in such a system. Circulation by a disk turbine impeller with six flat blades was studied through examination of tracer particle trajectories. Images showing flow patterns with the forward–reverse rotating impeller resembled those obtained with a unidirectionally rotating impeller in a baffled vessel. The pattern was characterized by a circulation loop whose pathway exits from the impeller rotational region and returns to that region past the wall and bottom of the vessel. Time‐series particle tracking velocimetry (PTV) images obtained during one forward–reverse rotation of the impeller showed that the flow near the vessel wall reduced the periodic fluctuation downstream and that a flow that was almost independent of time was induced near the vessel bottom. For the flow from the bottom to the impeller, unsteadiness was provided by proximity to the impeller. Based on the intensity distribution of the unsteady flow produced by this type of forward–reverse rotating impeller within the vessel, the unsteady flow was shown to have the potential to reach the region near the vessel wall. Copyright © 2010 Society of Chemical Industry     

Solid circulation and gas bypassing in an internally circulating fluidized bed with an orifice-type draft Tube

The effects of orifice diameter in the draft tube, particle size, gas velocities and bed height on the circulation rate of solids and gas bypassing between the draft tube and annulus have been determined in an internally circulating fluidized bed (i.d., 0.3 m ; height, 2.5 m) with an orifice-type draft tube. A conical shape gas separator has been employed above the draft tube to facilitate the separation of gases from the two beds. The circulation rate of solids and the quantity of gas bypass from the annulus to draft tube show their minimums when the static bed height is around the bottom of the separator. The circulation rate of solids increases with an increase in orifice diameter in the draft tube. At fixed aeration to the annulus, gas bypassing from the draft tube to annulus sections decreases, whereas reverse gas bypassing from the annulus to the draft tube increases with increasing the inlet gas velocity to the draft tube. The obtained solids circulation rate has been correlated by a relationship developed for the cocurrent flow of gas and solid through the orifice.     

Reverse osmosis with dynamically formed membranes from water-soluble polymers

Membranes were dynamically formed from poly(acrylic acid), poly(1-methyl-2-vinylpyridinium iodide), and methylcellulose on a Millipore filter. The effects of the conditions of membrane formation on reverse osmosis performances and the membrane structure were investigated. The primary factors that affect membrane performance were ascertained to be the kind and concentration of salts and the pH of the preparing solutions, the concentration and the polymerization degree of the membrane materials, the pore size of filters, and the pressure and circulation velocity during membrane formation. Two types of dynamically formed membranes, the membranes inside the filter and the membranes on the filter, were distinguished.     

贯通式潜孔锤在露天矿山地下采空区探查中的应用

针对洛钼集团三道庄露天钼矿区地下采空区钻孔勘探所面临的施工难题.提出利用贯通式潜孔锤与双壁钻杆组成的外平式钻具实施反循环钻进成孔工艺钻穿由塌陷或爆破崩落作用形成的复杂地层进而达到勘探下覆采空区的目的.现场工实践证明这种新方法行之有效.为其他露天矿山复杂地层下的空区钻孔勘探提供了借鉴.     

Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward–reverse rotating impeller

For an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller whose rotation proceeds with repeated acceleration, deceleration, and stop–reverse processes, liquid flow was studied through visualisation and measurement using particle tracking velocimetry (PTV). A disk turbine impeller with six flat blades was used with varied height settings. The impeller clearance and its forward–reverse rotation cycle characterised the impeller region flow: the radially outward flow in the deceleration process for the larger clearance relative to the vessel diameter of 1/3, and the axially downward flow in the acceleration process for the smaller clearance relative to the vessel diameter of 1/8. The flow patterns within the vessel resulting from the impeller's larger and smaller clearances were outlined, respectively, by double loops and a single loop of circulation, resembling the pattern produced by unidirectionally rotating turbine‐type impellers. The discharge flow was revealed to contain a comparable level of periodic circumferential velocity component, irrespective of the impeller clearance.     

我国磷化工现状及发展趋势分析

我国磷化工行业具有资源丰富、掌握部分核心技术、市场前景好的特点,将成为磷化工主要出口国。磷化工发展中存在资源利用率低,资源市场呈逆向分布,产业层次不高,面临能源、环保、外贸政策限制等问题。今后发展应构建磷化工循环经济产业链,产品向精细化、专用化方向发展,提高产业集中度,注意技术创新。     

聚苯胺修饰电极对甲醇的电催化氧化研究

应用电化学方法制备了Pt/PAn/GC电极,优化了苯胺在玻碳电极上的聚合条件,并对其进行了表征.结果表明,铂微粒在聚苯胺膜电极上具有很高的分散度,电极具有很大的比表面积,Pt/PAn/GC电极对甲醇电氧化的催化活性明显高于Pt/GC电极和Pt电极,在该电极上甲醇正向扫描和反向扫描时的氧化峰电流为58.68mA/cm2和50.00mA/cm2,为Pt/GC电极的1.6倍和1.7倍,为Pt电极的3.0倍和3.1倍,从而有效地提高了铂的催化活性,并得到在玻碳电极上聚合苯胺的最佳条件为扫描速度50mV/s,扫描上限1.2V.