旁路放风收集料改性磷石膏作水泥缓凝剂的 试验研究

水泥窑旁路放风收集料对磷石膏改性效果明显,2%～8%旁路放风收集料辅加3%的粉煤灰,与原状磷石膏混合、加水、搅拌和陈化制备得到改性磷石膏。相比原状磷石膏,将其作水泥缓凝剂时,水泥凝结时间可缩短80min以上,并且改性效果随着旁路放风收集料掺量增加而增强,初凝和终凝最高可缩短115min和130min,能有效解决原状磷石膏直接作水泥缓凝剂时,水泥严重缓凝的现象。     

水泥窑旁路放风技术及余热利用简介

为解决原料中钾、钠、氯、硫等元素对水泥窑生产过程造成的不良影响问题,使系统运行稳定,保证产品质量,采用旁路放风系统是目前解决该问题的最有效途径.旁路放风技术不仅拓宽了水泥生产原料的适应性,还可以生产优质水泥,使产品具有更好的市场竞争力.另外,旁路放风系统高温烟气热损失严重,利用现有余热发电技术将排出的高温烟气用于发电,在保证水泥窑正常生产的同时,还能取得一定的经济效益.     

循环流化床式旁路放风系统

针对新型干法窑常用的“风冷型”旁路放风系统成本高，热效率低等问题，本文介绍了一种新颖的“料冷型”循环流化床式旁路放风系统，就其原理及运行效果作了具体说明，对我国研究开发颇有启迪作用。     

旁路放风数学模型与计算程序

随着水泥工业的发展,越来越多的工厂需要采用含高挥发性组分（K2O、NaO、SO3、CI－）低品位的原、燃料煅烧水泥熟料。这样的原、燃料往往会引起预热器系统的结皮、堵塞,影响窑的正常运转,因此,有必要采取旁路放风措施。此外,为了生产低碱水泥,即使挥发性组分对窑的操作未     

增加飞灰处理后旁路放风量的计算和对系统的影响

通过对飞灰及入窑生料化学成分的综合分析,以及对3%、5%、8%和10%四种旁路放风量的模拟计算,确定合理的窑尾烟室旁路放风比例,并分项详细分析了增加旁路放风后对系统的影响。     

也门UCC水泥厂旁路放风系统的设计

<正>笔者于2007年参加了也门UCC 3 000t/d项目EPC总包工程基本方案的设计,当时根据该厂原料化学成分计算得出,生料中Cl-含量偏高,为降低入窑生料Cl-的含量,该线在窑尾设置了旁路放风系统。该工程于2008年初破土动工,2010年3月点火投料,运行不到3个月就达标达产,在正常生产时,旁路放风     

水泥窑旁路放风的设置及其效果

阐述了水泥生产中,影响生产操作及产品质量的主要有害物的去除机制,系统选择的原则及可能的效果及问题,为稳定水泥生产,扩大原燃料利用范围,提高资源的利用率,提高产品质量提供一种有效途径。     

水泥窑旁路放风技术的研究

介绍了水泥生产过程中钾、钠、氯、硫等挥发性物质的循环机理和结皮堵塞现象形成的机理,阐述了解决结皮堵塞现象的旁路放风技术及其在水泥生产过程中应注意的几个问题,同时针对旁路放风废气提出了新的利用途径。     

旁路放风风量的测试计算和理论计算

通过对国外某厂的旁路放风系统的测试,研究了旁路放风的影响,对比了理论公式计算值和实际测试值之间的误差。结果表明,该厂每旁路放风1%的窑尾气体,单位熟料热耗增加8.597kJ/kg左右,旁路放风有效减少了硫、氯和碱的内部循环,并且验证了理论公式的可靠性。     

旁路放风系统的工艺设计

使用氯、硫、碱含量高的原料和燃料,将使系统较易发生结皮和堵塞等故障。旁路放风对于防止预热器系统的结皮和堵塞有比较明显的作用,但旁路放风要损失部分热值,增加系统热耗,应根据原料成分中碱、氯、硫的含量确定是否采用旁路放风,放风量的计算应根据循环富集模型来进行。A工程放风量20%,其旁路气体从靠窑一侧的烟室上部抽出,掺入冷风后,直接进入袋收尘器后排出。A工程在取气点设置了急冷室,由冷风进口、热风进口、混合风出口及室体组成,冷风以涡旋方式与热风充分混合。     

气力输送工艺在煤粉输送中的应用

针对工业煤粉输送技术效率低、不安全等问题,介绍了稀相正压输送、密相正压输送和负压输送3种气力输送工艺的原理和使用现状,研究了密相输送工艺的原理和目前主流的栓流式密相输送技术。分析了稀相正压输送、密相正压输送和负压输送工艺各自的技术特点,并在投资、能耗、环保等方面进行对比。结果表明负压输送输送距离较短,稀相正压输送能量损失大、易发热,而密相正压输送固气比高、能耗低、管道和物料磨损小、噪声低、输送过程不易发热,更适合煤粉输送。     

粉煤灰长距离气力输送系统

0前言太原钢铁有限公司发电厂#1,#2,#7,#8锅炉电除尘系统收集下来的粉煤灰原采用水冲灰湿排系统。因用水量太大,故要求将粉煤灰湿排系统改为干排系统。改造工程由合肥水泥研究设计院承担,我们采用的改造方案为双仓泵气力输送系统;通过正压气力输送系统把收集下来的粉煤灰从发电     

Dense phase vertical pneumatic conveying

Vertical pneumatic conveying was studied in a 3-in. I.D. line, nineteen feet in length. Experiments were performed in both the empty line and in the line containing screen packing. Whereas in the conventional empty line choking occurs as the gas velocity is decreased, stable operation was possible in the screen packed line from the dilute conveying region down through the dense phase conveying region to the fluidizing region. A theoretical treatment proposed by Leung et al. to describe vertical transport of solids by liquids was used to predict the pressure drop/gas velocity relationship reasonably well for the screen packed line. Indications were obtained that the same equations may also be applied to conventional vertical pneumatic conveying in an empty line.     

Minimum transport boundaries for pneumatic conveying of powders

For the reliable design of pneumatic conveying systems, an accurate estimation of the minimum transport boundary is of significant importance. This paper presents results from an effort to establish a unified criterion for scaling-up the unstable boundary for the dense-phase pneumatic conveying of powders. An existing method of representing minimum transport criteria (based on superficial air velocity and solids loading) has been found inadequate for accurately predicting the unstable boundary, especially under diameter scale-up conditions. Using the experimental data from twelve different powders conveyed over a wide range of pipe lengths and diameters, a newly validated improved design procedure has been developed in this study using a Froude number based criterion at the entry to the pipe. The physical significance of Froude number in representing the minimum transport boundary is also discussed.     

Criteria for choking in vertical pneumatic conveying lines

Choking in vertical pneumatic conveying lines is not a clear-cut phenomenon. Different definitions and criteria are available in the literature. They are first reviewed in this paper. A mathematical definition for choking first proposed by the author was refined and presented with additional data. The concept of continuity wave and cluster formation, which were successfully applied to predict the transition between the bubbling and the turbulent fluidization, were then introduced to derive the basic relationship expected at choking. A semi-theoretical equation similar to the Richardson and Zaki equation for particulate fluidization was obtained from the available literature data. Hopefully, this mechanistic approach will eventually lead to a unified theory for choking in vertical pneumatic transport lines.     

Vertical pneumatic conveying of particle plugs

Dense-phase pneumatic conveying of solids offers many advantages over dilute-phase conveying. The lower air velocities, and, consequently, lower particle velocities, result in lower pipe wear and lower particle attrition. This paper describes an experimental program that has been undertaken to study the flow pattern of cohesionless solids in vertical transport and to measure the parameters influencing the pressure drop required to move a single plug of solids. Highspeed photographic techniques have been used to observe the flow pattern of polyethylene particles (diameter ? 3 mm) in the vertical riser section of a circulating unit constructed from pipes with an internal diameter of 50.8 mm. The flow pattern resembles that of square-nosed slugging in a fluidized bed. The solids move up as “plugs” of bulk solids that occupy the entire cross-section of the pipe. Particles are seen to “rain” down from the back of one plug and then to be collected by the front of the next plug. Collecting these particles causes a stress on the plug front which is transmitted by powder mechanics forces axially through the plug and radially to the wall. The pressure drop required to move a single plug of cohesionless solids through the transport pipeline was measured as a function of the plug length, particle properties, pipe diameter, and the frontal stress. The results of these experiments are compared with a theoretical model.     

Analyzing threshold velocities for fluidization and pneumatic conveying

In previous works we have shown that by defining various threshold velocities in terms of the modified Reynolds number as a function of the modified Archimedes number a generalized master-curve can be plotted. Then, using this curve, the ratio between various threshold velocities can be easily determined. However, all the threshold velocities were defined for mono-sized particles. The purpose of this paper is to show how the threshold velocities can be used to design of particle-fluid systems for particle size distribution. The analysis provides practical guides for various engineering scenarios, such as selecting the appropriate fluidization velocity for maximum fluidization and minimum entrainment and determining the conveying velocity in pneumatic systems. In addition, the analysis provides a guide to determine whether the deposited layer of particles at the pipe bottom is stationary or moving, for cases where the superficial velocity is smaller than the saltation velocity.     

气力输送斜槽的设计

气力输送斜槽是一种将物料和空气混合后用压缩空气作为动力输送的装置，它与机械输送方式相比具有结构简单、输送能力大、能耗少等优点，虽然有其局限性，但仍不失为一种非常经济的粉状或颗粒状物料的输送设备。本文对这种设备的结构作了分析，并对一些重要参数作了计算与分析，提出了气力输送斜槽的设计思想，并作出了气力输送斜槽应该在橡胶塑料工作中大力推广应用的结论。     

密相气力输送系统的比较

在建材、冶金、化工等行业中,现广泛应用的稀相气力输送技术,其气流速度高、固气比低,耗气量大,且不适用粒径大和相对体积质量大的物料输送。而低速、低压的密相栓流输送新技术,既可在输送过程中实施对物料的加热、冷却和烘干;且当物料速度减少或粉料流量增大时,具有较高的系统稳定性。目前,国内外已相继开发了多种密相栓流气力输送系统,其成栓方式包括有脉冲气刀式、挤压式和重管式等多种,均各具特点。其中,脉冲气刀栓流输送系统在运行时,输送固气比高、耗气量低,且成栓方式简单、有效,应成为密相气力输送设计时优先考虑的系统。