卷烟膨胀烟丝生产线冷端CO_2泵装置的优化改进

为解决干冰膨胀烟丝生产线冷端液体工艺泵因机械密封长期超压和气缚现象造成损坏发生CO2泄漏而导致紧急停机抢修的问题,对干冰膨胀线冷端工艺罐系统进行了优化改进。在工艺泵吸口前管路引一根气相平衡管至工艺罐顶部,当泵吸口前管路有CO2液体时,输送管路内气化的CO2气体通过气相平衡管线释放回工艺罐内,不会进入工艺泵体内。应用结果表明,工艺泵内的憋压和气缚现象消失了,机械密封受到保护。改造前机械密封平均一个季度更换一次,改造后机械密封使用5年未损毁,达到保护干冰膨胀线冷端工艺泵机械密封的目的。     

外浮顶罐充氮管网设计及有效性试验验证

为了预防外浮顶罐密封圈雷击火灾,提出在密封圈内充入氮气的保护方法.将安全含氧量作为充氮的惰化目标,对外浮顶罐充氮管网进行设计,并通过试验来验证充氮管网的有效性.试验得到了充氮流量、进出气孔数量及管径与有效充氮时间的关系.若以142 m3/h的流量对容量为10×104 m3的外浮顶罐密封圈内充氮,则46.5 min内可以达到充氮惰化目标.雷电预警时间为60 ～ 90 min的条件下,充氮时间小于预警时间,表明所设计的管网是有效的.     

航天器总装事故原因事件重要度分析

为解决传统安全性定量分析方法不能描述航天器总装这一复杂人-机-环系统的失效数据波动性和非严格逻辑关系的问题,结合生产实际,采用问卷调查的方法找出影响总装事故的风险因素,即导致事故的事件发生可能性、输入事件对输出事件的影响程度等。在验证调查数据的有效性之后,应用基于模糊数的模糊因果图(FCD),计算某航天器与支架车连接作业的事故风险可能性。提出原因事件重要度的计算方法。通过计算发现,人员注意力和发动机保护罩作用是导致发动机损伤的关键事件。与模糊事故树(FFT)、贝叶斯网络(BN)重要度计算结果对比表明,模糊重要度计算结果能反映事故发生可能性对原因事件发生可能性值的增减的敏感度。     

Surface modification of polypropylene non-woven fibers with TiO2 nanoparticles via layer-by-layer self assembly method: Preparation and photocatalytic activity

Polypropylene (PP) meltblown fibers were coated with titanium dioxide (TiO₂) nanoparticles using layer-by-layer (LbL) deposition technique. The fibers were first modified with 3 layers of poly(4-styrenesulfonic acid) (PSS) and poly(diallyl-dimethylammonium chloride) (PDADMAC) to improve the anchoring of the TiO₂ nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic TiO₂ nanoparticles to construct TiO₂/PDADMAC bilayer in the LbL fashion. The number of deposited TiO₂/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust TiO₂ loading. The LbL technique showed higher TiO₂ loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue (MB). Results showed that the TiO₂ modified fibers exhibited excellent photocatalytic activity efficiency similar to that of TiO₂ powder dispersed in solution. The deposition of TiO₂ 3 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr. TiO₂-LbL constructions also preserved TiO₂ adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of TiO₂ particles from the substrate outer surface. However, even in the third cycle, the TiO₂ modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.     

大吨位预应力锚具组装件锚固性能足尺试验

广州西塔节点层系采用大直径体外预应力拉索直接对钢管柱施加楼层平面内方向的体外预应力.选取3根φ7×199的预应力锚具组装件进行了50次周期荷载试验及静载锚同性能足尺试验.采用两台YC-1350型液压千斤顶同步顶推箱梁对预应力试验索进行张拉,测定拉索的周期载荷性能、静载锚同性能、拉伸弹性模量以及极限拉力时的总应变和锚杯与锚板间相对位移,考核锚具拉伸时锚固情况、拉伸过程及卸载后锚具的变形情况.结果表明,经过50次循环加载后试验索均无断丝,破断荷载超过12151kN,其他各项指标也均符合要求,因而能保证广州西塔体外预应力设计的安全性.     

Trends of perfluorochemicals in Greenland ringed seals and polar bears: Indications of shifts to decreasing trends

Time-series of perfluorinated alkylated substances (PFASs) in East Greenland polar bears and East and West Greenland ringed seals were updated in order to deduce whether a response to the major reduction in perfluoroalkyl production in the early 2000s had occurred. Previous studies had documented an exponential increase of perfluorooctane sulphonate (PFOS) in liver tissue from both species. In the present study, PFOS was still the far most dominant compound constituting 92% (West Greenland ringed seals), 88% (East Greenland ringed seals) and 85% (East Greenland polar bears). The PFOS concentrations increased up to 2006 with doubling times of approximately 6 years for the ringed seal populations and 14 years in case of polar bears. Since then a rapid decrease has occurred with clearing half-lives of approximately 1, 2 and 4 years, respectively. In polar bears perfluorohexane sulphonate (PFHxS) and perfluorooctane sulphonamide (PFOSA) also showed decreasing trends in recent years as do perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnA). For the West Greenland ringed seal population perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), PFDA and PFUnA peaked in the mid 2000s, whereas PFNA, PFDA and PFUnA in the East Greenland population have been stable or increasing in recent years. The peak of PFASs in Greenland ringed seals and polar bears occurred at a later time than in Canadian seals and polar bears and considerably later than observed in seal species from more southern latitudes. We suggest that this could be explained by the distance to emission hot-spots and differences in long-range transport to the Arctic.     

电子封装行业职业有害因素的辨识与分析

从电子封装行业工艺入手,依据国家颁布的职业有害因素分类目录及职业有害因素致病模型,针对电子封装行业插入式(DIP)及表面贴装(QFP/SOIC)制造工艺使用的材料、设备、条件、人员作业特点,对行业内具有共性的职业有害因素进行分析,对工艺过程中存在的职业有害因素作出辨识,并提出把硅粉尘、铅、氩气、高温、环氧树脂、氢氧化钾、噪声、酸雾、重复性静态作业、重复性动态作业等有害因素作为防控重点,为电子封装行业职业有害因素的危害量化评价及其防控措施制定提供了科学依据。     

泵设备机械密封泄漏事故防范技术探讨

分析了多起石化行业因果设备机械密封泄漏引发的重大火灾事故原因,研究表明:机械密封泄漏的诱发因素多是泵轴承严重故障后,机械密封过度磨损导致密封失效,使高温油料泄漏。为有效防范机械密封泄漏事故,提出防范措施:一是要加强泵轴承的监测,及时发现泵轴承存在的问题,避免泵轴承长期带病运行;二是要加强机泵组的联锁控制,当轴承出现严重故障后,能使机泵组及时停车,避免机械密封过度磨损导致泄漏。     

浮顶储罐弹簧式机械密封装置雷击危险性分析

针对大型浮顶储罐经常采用的弹性机械密封装置进行雷击危险性的理论分析和实验验证,明确此类弹性机械密封在雷击发生时存在的安全隐患,提出了建议措施,为大型浮顶储罐防雷击安全运行提供指导意义。     

渤海海域船舶防污设备铅封的可行性

从船舶排污口确认、船舶防污设备铅封要求和方法等方面，介绍说明渤海海域船舶防污设备铅封的可行性。