Establishment of Aqueous Film Forming Foam extinguishing agent minimum supply intensity model based on experimental method

In recent years, serious fire and explosion accident in petrochemical storage tanks have taken place frequently. Therefore, increasing the firefighting force in petrochemical parks is particularly important. The ambition of the paper is mainly studying the supply intensity of Aqueous Film Forming Foam (AFFF) extinguishing agent. Fire extinguishing agent demand calculation method that can be capable of matching fire scale is established by carrying out series of fire extinguishing experiments. 6% AFFF is chosen to carry out three groups of experiments respectively: fire extinguishing agent fluidity determination, series groups of small size simulation oil pool fire and 177 square meters of large oil pool fire extinguishing experiment. The situation of fire extinguishing on fuel surface of AFFF can be explored through experimental means under cold and hot conditions. The data obtained from experiments prove a higher conformity between covering process and covering model under the cold condition. The model can predict the cold coverage of AFFF effectively. After unifying the supply flow from each experiment, the statistics can be fitted and come to the minimum supply intensity algorithm of AFFF against the target storage tank specifications. The algorithm is used to estimate the minimum supply intensity when extinguishing full liquid surface fire. This model also can be used as reference for petrochemical fire protection.     

Seismic risk assessment of liquid overtopping in a steel storage tank equipped with a single deck floating roof

Major earthquakes have demonstrated that Natech events can be triggered by liquid overtopping in liquid storage tanks equipped with floating roofs. Thus, research on the dynamic behaviour of steel storage tanks with floating roofs is still required. In this paper, the seismic risk against liquid overtopping in a real steel storage tank with a floating roof was analysed using a simplified model that was validated by a refined finite element model based on the arbitrary Lagrangian-Eulerian approach. The simplified model utilizes the Lagrangian of a floating roof-fluid system and is capable of providing a response history of the floating roof. It was demonstrated that it could predict the maximum vertical displacement very accurately, while some differences were observed in the response history of vertical displacement. The computational time for a single response history analysis based on the simplified model amounted to a few minutes, which is significantly less demanding compared to hours required for response history analysis in the case of the refined FE model. The simplified model is thus appropriate for the seismic fragility analysis considering the overtopping limit state. It is shown that the fragility curves are significantly affected by the liquid filling level. The risk for liquid overtopping is quite high in the case of a full tank. However, by considering the variation of filling level during the year, the overtopping risk was observed reduced by approximately 30%. Alternatively, the approximate fragility analysis for the liquid overtopping can be performed by utilizing the Eurocode formula for the vertical displacement of liquid. This approach is straightforward, but the formula does not account for the higher mode effects, which may result in overestimated seismic intensity causing overtopping, as discussed in the paper.     

新疆某石化企业周边土壤中多环芳烃调查与评价

本文以新疆某石化企业周边土壤作为调查对象,分析其中16种多环芳烃的含量,分析结果表明,该石化企业周边土壤中多环芳烃的含量处于安全水平。     

A/O摇动床工艺处理石化废水的研究

针对国内许多石油化工废水处理工艺中氨氮降解效果差的问题,采用新型Biofringe填料设计一体化A/O摇动床工艺,对反应器处理石化废水的效果和运行参数进行了实验。结果表明:在水力停留时间为20.8h,回流比为3.5h,COD的去除率可以达到90%以上,NH3-N的去除率可以达到95%以上,TN的去除率可以达到70%以上。通过1年多的小试,反应器具有动力消耗低,抗冲击能力强,操作稳定等特点,为进一步在石油化工废水处理中的应用提供了实验依据。     

惠州大亚湾石化区综合污水处理厂技改尝试

为提高污水处理效果,降低运行成本,惠州大亚湾石化区综合污水处理厂针对实际来水状况,对原有工艺进行一系列工艺技术改造,改造后工艺系统运行良好,出水水质较高,达到广东省《水污染物排放限值》(DB4426-2001)第二时段一级标准。惠州大亚湾石化区综合污水处理厂的小水量技术改造表明:通过有效的技术改造和调整技术管理措施,可提高污水处理率、减少环境污染、降低生产成本、减少资源浪费。     

反渗透膜法海水淡化技术在大连石化公司的应用

大连石化公司采用反渗透膜法海水淡化工艺为生产装置提供淡水资源,其用水取自炼化装置冷却换热后的海水,不额外增加海水的取用量,降低了成本。装置采用常规预处理加三级反渗透膜分离技术,同时配备了能量回收装置,将反渗透高压"浓水"的能量转换到低压的原海水中,使得能耗大大降低。文章介绍了该工艺的流程及其技术特点,该装置节能、节水,其产品水质量达到甚至超过了中压锅炉补给水的要求。工程运行稳定,对沿海同类企业有借鉴意义。     

大庆石化公司化工三厂中水回用探讨

中水回用是企业普遍采用的节水减排方式之一。大庆石化公司化工三厂中水回用装置采用目前国内较为先进的工艺,中水主要经过曝气生物滤池、水处理生化系统、臭氧尾气回收处理——预臭氧化系统、二氧化氯发生系统等单元的处理得以回用。装置投用后满负荷生产每年可减排污水约80多万吨,减排COD约80t。文章针对存在的问题进行了分析并提出了对策措施。     

劳动力外流与农村公共事务治理

新世纪以来,伴随着劳动力的大规模外流,农村公共事务治理呈现出集体经济困难、人居环境恶化和农田水利废弛等各个方面全面衰败的景象。灌溉作为农村典型的公共事务,对于从微观层面揭示劳动力大规模外流与农村公共事务治理衰败之间的因果关系具有代表性意义。关于劳动力流动对农村公共事务治理的影响,在已有的实证研究文献中鲜有讨论。本文基于2014年清华大学中国农村研究院对全国21个省份的调查数据,建立二元logistic回归模型,对1 507个农户的灌溉行为进行计量分析,发现农户家庭劳动力外流对农户参与集体灌溉具有显著的负面影响。这表明,在快速城镇化的过程中,劳动力外流为经济增长做出贡献的同时,也弱化了农村集体行动能力,对农村公共事务治理产生了显著负面影响。同时,计量结果表明:平原地区、水资源自然条件一般的村庄、耕地位于灌渠的中游、农户的承包地经营面积较大、农户的承包地块数较多、灌溉对农户家庭收入的重要性较大以及村庄对私自挖渠取水有惩罚措施等变量对农户参与集体灌溉有显著的正面影响;村庄位于城市郊区、地区经济发展水平较高和灌溉缺水历史等变量对农户参与集体灌溉有显著的负面影响;用水户协会的有无对农户是否参与集体灌溉没有显著的影响,原因是中国农村大多数用水户协会是行政力量推动下的产物,实际作用并不明显。上述结果表明:近20年来的大规模劳动力流动为中国经济高速增长做出贡献的同时,给农村公共事务的治理带来显著的不利影响。研究大规模劳动力流动背景下的农村公共事务挑战及其应对,具有重要的理论价值和实践意义,应作为未来重要的学术方向。由于农村劳动力外流是难以逆转的发展趋势,如何培育新的历史条件下的合作资源,实现农村社会有效的集体行动机制,是未来扭转农村公共事务治理衰败的关键。     

Determinants on Rural-Urban Labor Migration in China： Empirical Analysis on the Effect of Rural Cooperate Medical Insurance based on Cross-Sectional and Longitudinal Data

This paper studies factors influencing rural-urban labor migration in China,particularly the implementation of rural cooperative medical insurance(RCMI) in the year 2003.With the support of data analysis from the year 2000,2004 and 2006,clear linear correlations are found between gender,income,health condition and rural-urban labor flow,whereas the impact of education and employment status are more complicated.More importantly,results from regression show that the establishment of RCMI in countryside of China not only inhibits rural residents from seeking employment outside the village,but also pulls back rural people who have already worked in cities.When regional dimension is concerned,the pure composite effect of RCMI on rural labor flow is less significant in coastal areas with better economic performance and medical service.     

污泥停留时间对污泥减量化的影响

污泥停留时间不但决定系统剩余污泥的排放量,还直接影响到污泥的絮凝沉降性能及活性等。由实验可知:污泥停留时间延长,可导致微生物缺乏营养,减少污泥产生量;从而导致SVI升高,污泥负荷降低。因此,延长污泥停留时间减少剩余污泥量,可以节省尿素和KH2PO4投入量,从经济上节省运行成本。