阳极焙烧的烟气净化技术分析

阳极焙烧过程中产生大量的含有沥青焦油、粉尘、二氧化硫、氟化物等有害烟气,严重污染环境.考虑到投资、运行和维护等,目前国内大部分企业的焙烧烟气治理采用电捕干法净化技术,但电捕干法净化系统由于着火、腐蚀、电捕除尘器极板和料斗清灰困难等问题不能实现长周期连续运行.而且电捕干法净化系统对氟的治理效果不好存在工艺缺陷.本文以焙烧烟气的电捕干法净化工艺为基础,提出电捕干法净化系统存在问题的解决方法,并提出焙烧烟气综合治理的优化工艺,改善电捕干法净化系统的工艺缺陷.     

电解铝工业烟气干法除氟过程的吸附机理

七十年代以来,世界铝工业界广泛应用干法除氟技术,大大简化了烟气净化回收流程,湿法洗涤效率低于干法,只有85～95％,而干法可以达到98～99％。而且氟的回收是直接的。目前,工业上采用的干法除氟系统有流化     

高压干法水下焊接装备与技术的发展

介绍了国内外高压干法水下焊接模拟实验装置和高压干法水下焊接维修作业装备系统的发展现状,重点论述了高压下对焊接电孤行为的研究情况,包括环境压力对焊接电弧形态、稳定性、电弧电压特性、电弧电流密度、电弧温度场等的影响及变化规律.指出了高压干法水下焊接技术的发展方向及我国研究高压干法水下焊接技术的必要性.     

非常温作用下水玻璃旧砂的干法再生性研究

干法再生水玻璃旧砂工艺,设备简单、成本低、二次污染少,但再生砂的脱膜率低、质量不高。如果再生前将水玻璃旧砂进行非常温处理(加热或冰冻)可以提高再生脱膜率,改善再生砂的性能。本文测试了普通干法再生、"加热-干法"再生和"冰冻-干法"再生的脱膜率,对比了几种循环再生砂的再粘结强度、可使用时间和残留强度。试验结果表明:普通干法再生的脱膜率为5%～10%,320℃"加热-干法"再生的脱膜率为20%～25%,-40℃"冰冻-干法"再生的脱膜率为35%～40%;而320℃"加热-干法"再生砂的再粘结强度和可使用时间最大,-40℃"冰冻-干法"再生砂的残留强度最低、溃散性最好。这一研究结果为改进水玻璃旧砂再生工艺、改善水玻璃再生砂性能等提供了有意义的新方法。     

基于电液比例阀的干法辊压造粒机工作特性研究

普通电磁阀控制的干法造粒机工作过程中挤压辊常常出现偏斜和振动,对粉料成型质量产生严重影响。采用电液比例控制技术对干法辊压造粒机液压系统进行改造,通过分析挤压辊咬入角受力平衡方程,提出影响挤压辊工作特性的主要因素是粉体物料与挤压辊表面的摩擦因数。将AMESim软件与ADAMS软件相结合,针对改造前和改造后的干法造粒机搭建机液联合仿真模型,对比分析干法辊压造粒机工作特性随摩擦因数变化规律。仿真结果表明：与改造前干法辊压造粒机工作特性相比,改造后的干法辊压造粒机其液压缸无杆腔压力,挤压辊位移、速度、加速度、角速度、角加速度等曲线变化更加平稳,且增大粉体物料与挤压辊表面的动摩擦因数,可明显改善干法辊压造粒机运动的平稳性。     

空气重介流化床干法选煤成套设备

本文着重介绍了空气重介流化床干法选煤技术的理论依据和关键技术及其相应的解决方法,介绍了空气重介流化床干法选煤成套设备的主要技术参数,简述了空气重介流化床干法选煤技术的发展状况及前景。     

焙烧烟气双干法净化运行维护实践

本文分析了国内某炭素厂双干法净化系统运行中存在的问题。通过对净化系统设备改良、日常维护、优化人员点检操作管理，解决了双干法净化系统稳定连续运行的技术问题，降低了设备运行维护成本，对使用双干法净化系统的企业有可借鉴之处。     

高炉煤气干法除尘PCS7控制系统介绍

高炉干法除尘是在高温条件下进行的煤气净化技术,与湿法除尘相比,干法除尘可简化工艺系统,具有占地面少,无二次环境污染,无需对污水进行处理,生产运行费用低,合理利用煤气余热,提高煤气热效率,可配套建设高炉顶压发电设备。根据目前国内中、小型高炉已具有成功的生产运行经验以及干法除尘的优势等,本设计采用高炉煤气干法除尘工艺系统进行煤气精除尘。     

高压干法水下焊接技术发展现状

随着海洋石油和天然气工业的发展，海洋工程日益向深海挺进，发展水下焊接技术刻不容缓。高压干法水下焊接以其焊接质量高、接头性能好等优点越来越受到重视。概括介绍了国内外高压干法水下焊接模拟实验装置和高压干法水下焊接维修作业系统的发展现状，重点论述了高压下对电弧行为的研究情况，包括环境压力对焊接电弧形态、稳定性、电弧电压特性、电弧电流密度、电弧温度的影响及变化规律。指出了高压干法水下焊接技术的发展方向及我国研究高压干法水下焊接技术的必要性。     

车载式干法除尘装煤车

文章阐述了炼焦设备装煤车的装煤工艺、结构，开发车载式干法除尘装煤车的意义以及车载式干法除尘装煤车的除尘工艺。     

局部干法环境下GMAW横向焊接熔滴过渡特性

提出了一种水下结构件局部干法横向焊接方法,该方法通过对排水罩结构进行设计,使高压气体在排水的同时在排水罩内部形成向上流动的风场,利用风场对熔池的吹袭作用来抑制熔池下淌. 采用高速摄像技术研究了在侧向风场作用下GMAW焊的熔滴过渡特性. 结果表明,在短路过渡状态下,由于受到侧向风场的影响,更容易发生B型短路过渡. 在滴状过渡时,由于熔滴体积较大,侧向风场的支托作用不明显,熔滴沿焊丝倾斜向下过渡到熔池中. 在射流过渡时,侧向风场对电弧的影响较小,使熔滴略微向上偏斜,有助于减小熔池下淌程度,获得较好的焊缝成形质量. 研究结果对于水下结构件横向焊接质量控制有一定的参考价值.     

生阳极制造工艺流程改进的分析与探讨

本文通过对炭阳极生产中生阳极制造工序方案的分析,提出对生阳极制造工序的某些工艺流程进行改进的设想。主要着重于中碎筛分系统、干物料粒度的粒级及种级、配料仓容积大小等方面的改进,以便达到简化生阳极制造工序流程、减少使用设备、降低厂房高度的目的。     

Uphill quenching of aluminium: a process overview

Abstract

Uphill quenching is a relatively little known process to reduce quenching stresses in heat treatable aluminium alloys. This process involves solutionising of the alloy followed by cold water quenching then immediately cooling in either dry ice or liquid nitrogen which is followed by reheating, most often in either boiling water or by blasting with high pressure steam and then the last step in this process is tempering. Residual stress reduction of >90% has been reported. An overview of uphill quenching methodology is provided here.     

Dynamic effects during a high-speed sinter-forging process

The paper reports on an investigation into the various technological aspects of a high-speed sinter-forging process. Experiments were conducted and measurements were made in the development of barrelling, strain variations at the free surface and densilication during dry and lubricated high-speed cold forging of sintered copper powder discs. The relationship between the frictional stress at the interface and other process variables is discussed and an analysis is given for the calculation of pressure distribution and die load by the solution of the equations of equilibrium taking barrelling into consideration for axial symmetry and plane strain sinter-forging conditions. Results are discussed critically to illustrate the interaction of various processing parameters involved during high-speed sinter-forging process and are presented graphically.     

Hydrogen entry into steel during atmospheric corrosion process

Hydrogen entry and permeation into iron were measured by an electrochemical method during atmospheric corrosion reaction. The hydrogen permeation was enhanced on passive films because the hydrogen adsorption increased by the hydrogen evolution mechanism which is different from that on a bear iron surface. The permeation rate during a wet and dry corrosion cycle showed a maximum in the drying process depending upon the surface pH and the corrosion potential. The pollutant such as Na₂SO₃ which decreases the pH and the corrosion potential causes an increase in the permeation rate. The mechanism of the change in the permeation rate during the wet and dry cycles is explained by the polarization diagram of the electrode covered by thin water layer.     

The friction modeling of different tribological interfaces in extrusion process

Friction and lubrication are of great importance in many important metal forming processes such as sheet metal forming, forging and extrusion. With the products being more complex, it may utilize different lubrication medium in different tool/workpiece interface in which the metal flow could be controlled more effectively. While there is a substantial body of published research on friction modeling in metal forming processes, there has been relatively little work on forming process in which different tribological interfaces such as lubricant/grease, lubricant/dry and dry/grease are existed. The objective of this research is to investigate the friction distribution in combined forward and backward extrusion process. A realistic model of friction is developed to determine the friction coefficient of lubricated tool/workpiece interface. The friction coefficient of the other interface in which grease or different lubricant may applied is then determined by a coupled FEM and experiment investigation. Both the simulation and experimental data will be presented.     

350kA预焙槽干法无效应启动

详细介绍了350kA干法无效应启动,装炉物料的准备、以及焙烧时间、焙烧升温速度、阳极分布,侧壁钢棒温度等技术条件的控制和分析。     

Improvement of dry EDM process characteristics using artificial soft computing methodologies

Dry electrical discharge machining (EDM) is an environmentally-friendly alternative of die-sinking EDM process, which it uses gaseous medium instead of liquid as a dielectric. Due to contribution of too many parameters in this process, selection of optimal parameters to increase the process performances is a really crucial concern. In this work, a predictive model based on back-propagation neural network has been applied to correlate the inputs and outputs of dry EDM process. Herein, the inputs were gap voltage, pulse current, pulse on time, duty factor, air intake pressure and rotational speed of tool, and also the main outputs were material removal rate (MRR) and surface roughness (SR). Firstly a back-propagation (BP) and radial basis function neural network have been developed based on data generated from literature [Saha and Choudhary Int J Mach Tools Manuf 49:297?C308 (2009)]. Then, the accuracy of proposed models has been checked by their values of error percent via testing data. Hereafter, the most accurate model was served as an objective function to optimize the process using artificial bee colony (ABC) algorithm. In optimization stage, firstly a single objective optimization was fulfilled to determine the optimal factors related to each output separately. Then a multi-objective optimization was implemented to calculate the best solutions in the case of higher MRR and lower SR simultaneously. Results indicated that the predictive model can estimate the dry EDM process precisely, and also the ABC algorithm could find the optimal solution sets logically.     

Cutting conditions for finish turning process aiming: the use of dry cutting

To avoid the use of cutting fluids in machining operations is one goal that has been searched for by many people in industrial companies, due to ecological and human health problems caused by the cutting fluid. However, cutting fluids still provide a longer tool life for many machining operations. This is the case of the turning operation of steel using coated carbide inserts. Therefore, the objective of this work is to find cutting conditions more suitable for dry cutting, i.e., conditions which make tool life in dry cutting, closer to that obtained with cutting with fluid, without damaging the workpiece surface roughness and without increasing cutting power consumed by the process. To reach these goals several finish turning experiments were carried out, varying cutting speed, feed and tool nose radius, with and without the use of cutting fluid. The main conclusion of this work was that to remove the fluid from a finish turning process, without harming tool life and cutting time and improving surface roughness and power consumed, it is necessary to increase feed and tool nose radius and decrease cutting speed.     

陶瓷刚玉磨料行星磨干法造粒研究

本文对陶瓷刚玉磨料干凝胶颗粒进行形状控制的造粒工艺进行了研究,对影响造粒的主要参数进行了讨论.采用扫描电子显微镜(SEM)对磨料的颗粒形貌进行了观察,采用筛分法对磨料的粒度分布进行了测定.研究结果表明:合适的料球比既能使干凝胶颗粒受到磨介的充分作用,又能避免过粉碎;磨介形状和大小的级配对颗粒形状的控制有着重要影响;合理的球磨转速使磨介对干凝胶颗粒的作用得到充分的发挥;通过对造粒工艺参数的适当选择,获得了粒度分布范围集中的等积形陶瓷刚玉干凝胶颗粒粉料.