自动扶梯倒转原因以及倒转应急处理的措施探究

自动扶梯在各个商场、车站、地铁站的应用越来越多,随之而来的安全事故也在逐渐增多。自动扶梯导致的安全事故类型比较多,自动扶梯的倒转则是众多安全事故中比较主要的一种,所以加强对自动扶梯倒转原因以及倒转的应急处理措施研究具有非常重要的意义。     

电站蒸汽锅炉的改造经验及方案

介绍了将35t/h顺转链条锅炉改成抛煤机倒转链条锅炉并用于发电的改造方案,技术改造后,锅炉蒸发量达到了额定值,热效率提高8%,炉渣含碳量下降到7%以下,每年可节约原煤约6000t,具有较好的经济效益。     

管柱防倒转装置的研制及应用

油田在使用螺杆钻进行钻进作业时,常采用在井口打背钳的方式来防止管柱的倒转,这种方法的缺陷在于其安全性能较低。针对这一问题,设计了一种管柱防倒转装置,在钻进时配合使用该装置,可以有效的制止管柱的倒转。现场应用结果表明,该装置具有结构简单、可重复使用的特点,值得推广。     

钢丝绳锭子导开架中倒转驱动装置的设计

简要介绍了钢丝绳芯输送带平板硫化机生产线中钢丝绳锭子导开架的结构形式,分析了锭子座上钢丝绳工字轮倒转时的特点及转动原理,通过计算倒转驱动减速机所需输出扭矩,从而确定驱动减速机的选型。     

回转窑停车时烧坏快熔保险问题及解决办法

水泥厂的窑中直流传动装置电源,以往常选用北京整流器厂生产的KGSF11-1000安/230伏半控桥整流装置。用该装置存在的问题是在停窑时常烧断快熔保险。我厂在16个月中烧坏81个,这便加大了维修工作量,并消耗大量纯银质的快熔保险,也影响熟料的产、质量。烧坏快熔一般都是发生在停窑产生倒转时,倒转角度越大,速度越快,那几乎无疑要烧坏。其原因是窑倒转时,电动机成为发电机运行状态,产生的电势Ea通过电抗器L、续流     

印橡胶业要求修正倒转关税 削弱中国产品在印优势

印度《金融快报》6月12日报道,包括6 000余家制造企业的印度橡胶行业希望联邦预算修正倒转关税结构,终结中国橡胶制品在印市场享有的不公平竞争优势。全印度橡胶工业协会(AIRIA)表示,印度橡胶业原材料进口关税最高而制成品关税最低,这种倒转关税结构抑制了橡胶行业增长。希望正努力促进制造业复苏的新政府能在预算中解决这种不正常情况。     

降低有底柱分段崩落法损失的途径

锦屏磷矿属前震旦纪海相沉积的变质矿床,矿区主要构造为一北北东向南南西倾没的倒转背斜,有用矿层分布于倒转背斜的两翼。东翼的东山矿区矿石类型为细粒磷块岩,矿体呈透镜状产出,构造较复杂。矿体走向为NE45°～70°,倾向SE,矿体走向长1012米,厚度2～55米,倾角40°～70°,矿石中等稳固,f=6～8。矿体顶盘为云母片岩和大理岩,均为中等稳固,f=6～8。     

罗茨风机出口加装止回平衡阀预防风机停车时倒转

正脱硫罗茨风机停运或紧急停车过程中,由于管道系统出口压力高于进口压力,无法控制可燃气体倒流,风机瞬间发生倒转导致叶轮破碎,极易产生可燃气体泄漏;如果叶轮破碎产生火花就会发生可燃气体着火、爆炸和环境污染,给企业造成巨大经济损失。为使脱硫罗茨风机在开、停机过程中更合理、更安全稳定运行,在风机出口加装止回平衡阀,预防罗茨风机停车时倒转。1罗茨风机止回平衡阀罗茨风机止回平衡阀主要由阀体、舌管、阀板     

柯克亚地区天然气地球化学研究

通过对天然气化学组成、碳同位素组成、非烃同位素组成研究综合分析柯克亚地区天然气成因。结果发现柯克亚地区天然气存在原油裂解气和干酪根裂解气两类裂解气。发现天然气乙烷、丙烷碳同位素倒转和油气碳同位素不符合碳同位素分馏原理的主要原因是干酪根裂解气的混入。     

多功能水泵控制阀应用实例

宝钢集团上海五钢有限公司新水厂供水泵出口阀门改用多功能水泵控制阀,取代原先的微阻缓闭止回阀和电动阀后,解决了水泵停泵时因止回阀关闭不严造成水泵倒转严重的问题,同时开停泵操作简便,停泵时关闭过程平稳,止水严密,消除水锤效果明显。     

Solid–liquid mass transfer characteristics of an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller

To develop an enhanced form of solid‐liquid apparatus, an unbaffled agitated vessel has been constructed, fitted with an agitation system using an impeller whose rotation alternates unsteadily in direction, i.e. a forward‐reverse rotating impeller. In this vessel, solid‐liquid mass transfer was studied using a disc turbine impeller with six flat blades. The effect of impeller rotation rate as an operating variable on the mass transfer coefficient was evaluated experimentally using various geometrical conditions of the apparatus, such as impeller diameter and height, in relation to the impeller power consumption. Mixing of gas above the free surface into the bulk liquid, i.e. surface aeration, which accompanied the solid‐liquid agitation, was also investigated. Comparison of the mass transfer characteristics between this type of vessel and a baffled vessel with a unidirectional rotating impeller underscored the sufficient solid‐liquid contact for prevention of gas mixing in the forward‐reverse rotation mode of the impeller. Copyright © 2008 Society of Chemical Industry     

Effect of inlet particle arrangement on separating property of a cyclone separator

Different arrangements of particles on the inlet section exert different effects on the separation property of a cyclone separator. Sorting classifier with different heights was connected in series with a conventional cyclone, positive rotation cyclone, and reverse rotation cyclone respectively, to investigate the effect of particle arrangement on the separation property and inner flow field. Results indicate that the implementation of a sorting classifier increases the pressure drop and energy consumption of a cyclone separator. The taller the sorting classifier, the larger the flow is. The energy consumption in positive rotation cyclone is closer to that in reverse rotation cyclone. Meanwhile, the tangential velocity in inner flow field is higher and the separating property is enhanced. The reverse rotation cyclone relieves the fishhook effect, whereas the positive rotation cyclone eliminates such effect. The reverse and positive rotation cyclones demonstrate an improved separating property for particles smaller and greater than 1 μm, respectively. Moreover, the reverse rotation cyclone demonstrates superior overall separation, but the positive rotation cyclone demonstrates a greater classification effect than the reverse rotation cyclone.     

Agitation requirements for complete solid suspension in an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller

Background: To develop a new type of solid–liquid apparatus, we have proposed the application of an agitation system with an impeller whose rotation alternates direction unsteadily, i.e., a forward–reverse rotating impeller. For an unbaffled agitated vessel fitted with this system, the suspension of solid particles in a liquid was studied using a disk turbine impeller with six flat blades. Results: The effects of the solid–liquid conditions and geometrical conditions of the apparatus on the minimum rotation rate and the corresponding impeller power consumption were evaluated experimentally for a completely suspended solid. The power consumption for a just suspended solid with this type of vessel was comparable with that for a baffled vessel with a unidirectionally rotating impeller, taking the liquid flow along the vessel bottom into consideration. Conclusion: Empirical relationships to predict the parameters of agitation requirements were found. A comparative investigation demonstrated the usefulness of the forward–reverse rotation mode of the impeller for off‐bottom suspension of solid particles. Copyright © 2007 Society of Chemical Industry     

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.     

长输泵高压变频器突停及处理

以抚鲅成品油管线长输油泵变频器所出现的突停故障为例,介绍了变频器突停后出现的反转故障和不能启动现象,分析了高压变频器在零点控制上的缺陷,并提出解决此类故障的方法。     

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     

圆盘涡轮式搅拌器的搅拌性能比较分析

在椭圆封头搅拌槽中根据行业标准建立了4种圆盘涡轮式搅拌器的几何模型,利用标准k-ε湍流模型和多参考系(MRF)方法,研究了叶片形状、搅拌速度、旋转方向和流型转变对搅拌功率、排出流量、泵出效率和剪切速率的影响。结果表明：叶片形状对功率、排出流量、泵出效率和流型转变的临界安装高度均有影响;径向流条件下,泵出效率排序为圆弧叶(反)>弯叶(正)>箭叶(反)>圆弧叶(正)>平直叶>箭叶(正)>弯叶(反);流型由径向流转变为轴向流后,搅拌功率及径向排出流量均下降。对标准搅拌器的性能评估为工业搅拌设备的选型和设计提供了参考依据。     

静端导电块旋转镀银工艺及设备的研究

采用旋转电镀银的方法进行静端导电块的电镀,研究了旋转镀时的转速、有无反转设置、施镀电流密度、阳极电力线均布套筒(板)设置对镀层厚度均匀性的影响,并采用对比方法对施镀件在不同条件下,不同直径上的镀层的平均厚度、同一直径上镀层厚度的最大差值以及不同直径上镀层平均厚度的差值进行了比较。结果表明,施镀工作电流密度为0.8 A/dm~2、转速为10 r/min,设置阳极电力线均布套筒(板)时,镀层均匀性好,d为70 mm处与d为40 mm处平均镀层厚度相差仅为0.1μm。该阴极旋转镀装置在自动生产线上已成功实现了应用。     

登革病毒反向遗传学技术的研究进展

登革病毒(dengue virus,DENV)是流行于世界范围内的重要虫媒病毒之一,近年来其传播范围的不断扩大给疾病防控带来了极大困难。反向遗传学技术作为一种重要手段,广泛应用于RNA病毒的相关研究,自1991年第1次成功构建DENV感染性克隆以来,明显加速了DENV相关领域的研究。本文总结了DENV反向遗传学技术的构建策略及技术突破,为DENV致病机制研究及疫苗研发提供新思路。     

反向压差危害及防止措施的分析和探讨 零极距电解槽运行问题专题二

分析了零极距电解槽反向压差产生的原因、危害并提出了防止其产生的措施。