Effect of vibration condition and inter-particle frictions on the packing of uniform spheres

We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores.     

给水泵密封水系统对机组真空的影响

介绍了银川热电厂二期工程投运一年以后,多次出现凝汽器真空缓慢下降的现象。在机组系统严密性试验合格的前提下,经多次观察,发现是给水泵密封水系统漏空气造成的。在采取了一些相应措施后,解决了这个问题。     

Connecting the second exhaust-heat boiler to the operating first one under the conditions of flow circuits of combined-cycle plants with two gas-turbine units and one steam turbine

Problems arising with connecting the second exhaust-heat boiler to the first exhaust-heat boiler under load in the case of flow circuits of combined-cycle plants of type PGU-450 are considered. Similar problems exist for two-boiler single-turbine units of type PGU-325 and for two-boiler single-turbine units of traditional steampower plants with an output of 200–300 MW upon connection of the second furnace of a two-furnace boiler to the operating first furnace. Analysis of the temperature-induced stressed state and of the cyclic strength of thick-walled elements of the steam-water conduit of PGU-450 and of two-furnace boilers of two-boiler single-turbine units with an output of 200–300 MW (the check valve, the inlet header of the water economizer) is used for determining the steam temperature differences in the high-pressure conduits to the steam turbine and the order of connection of the second exhaust-heat boiler to the operating fist one. Modes of enabling a two-boiler single-turbine unit of a combined-cycle plant, which are most “rigid” from the standpoint of thermal strength, are determined. __________ Translated from élektricheskie Stantsii, No. 2, February 2006, pp. 11–17.     

氧化铝熟料单筒冷却机节能技术改造

本对影响氧化铝熟料单筒冷却机冷却效率的因素进行了分析，并提出了相应的节能技术改造措施，取得了明显的节能效益。     

芳烃抽提装置技术改造

由于中国石化锦西石化分公司600kt／a连续重整装置的建设，芳烃抽提装置的原料由原来的脱戊烷油变为Ce组分。为此，对抽余油水洗塔和芳烃分离部分的苯塔塔盘，以及苯塔塔顶和塔底抽出部分进行了改造，更换部分机泵和增加变频泵，并将常规仪表改为DCS控制。改造后装置实现一次开车成功，生产出合格产品。抽余油中总芳烃含量小于0．1％，苯回收率达到99%以上。     

VRDS装置常压分馏塔系统的问题分析

胜利炼油厂重油加氢 (VRDS)装置的常压分馏塔为填料塔 ,2 0 0 1年检修开工后该系统出现异常 ,经过查找分析 ,确定轻烃 /产品减压渣油换热器和柴油汽提塔重沸器内漏是装置异常的主要原因     

催化重整装置的扩能改造

介绍湛江东兴炼油厂的重整装置由200kt／a扩能至300kt／a中有关催化重整反应动力学模拟计算软件的应用、反应工艺技术的改造、装置标定的情况。结合装置实际情况，采用两段装填、两段混氢技术提升了装置的技术水平。标定结果表明，改造后的装置达到了预期目的。     

变频器的现状与发展动向

本文从开关元件、调制策略、控制保护、主电路拓扑及智能化五个方面，综述了变频器的现状与发展动向。     

某铅锌矿选矿尾矿综合利用试验研究

针对选矿尾矿的特性，采用高选择性的3ACH捕收剂、F—1抑制剂，回收了绢云母含量分别达96％和64％以上的一、二级绢云母产品。经应用试验表明：绢云母一级品在橡胶中的补强性能基本达到了沉淀法白炭黑水平，二级品也全面超过硅铝炭黑的补强性能。     

40kg试验焦炉的研制

文章介绍了40kg试验焦炉，分析和比较了试验焦炉与生产焦炉的差异，指出它们之间的模拟条件是炭化室宽度、煤料堆密度、炼焦速度和单向传热。