Combustion products toxicity risk assessment in an offshore installation

Products of a hydrocarbon fire accident have both chronic and acute health effects. They cause respiratory issues to lung cancer. While fire is the most frequent phenomenon among the offshore accidents, predicting the contaminants’ concentration and their behavior are key issues. Safety measures design, such as ventilation and emergency routes based only on predicted contaminants’ concentration seems not to be the best approach. In a combustion process, various harmful substances are produced and their concentration cannot be added. The time duration that any individual spends in different locations of an offshore installation also varies significantly. A risk-based approach considers the duration a person is exposed to contaminants at various locations and also evaluates the hazardous impacts. A risk-based approach has also an additivity characteristic which helps to assess overall risk.Through the current study, an approach is proposed to be used for risk assessment of combustion products dispersion phenomenon in a confined or semi-confined facility. Considering CO, NO₂ and CH₄ as the contaminants of concern, the dispersion of the substances over the layout of the facility after a LNG fire is modeled. Considering different exposure times for three major parts of the facility including the processing area, office area and the accommodation module, the risk contours of CO, NO₂ and CH₄ over the entire facility are developed. The additivity characteristic of the risk-based approach was used to calculate the overall risk. The proposed approach helps to better design safety measures to minimize the impacts and effective emergency evacuation planning.     

多介质潜流人工湿地的水动力过程模拟

水动力过程是湿地净化功能发挥的重要机制之一.根据脉冲示踪试验,获得潜流人工湿地的水力停留时间分布曲线.针对其"多峰"现象,利用数学软件MATLAB7.0分别将对数正态分布、对流扩散模型以及考虑延迟的连续完全混合反应器模型时脉冲示踪试验数据进行叠加模拟,同时利用多流弥散模型拟合分析,结果表明:叠加模型和多流弥散模型均能较...     

厌氧污泥性质对超声破解效率的影响

超声破解是污泥溶胞-隐性生长处理的一种重要前处理手段,破解效果受到超声条件及污泥性质的影响。以厌氧污泥破解后溶解性化学需氧量的增加值和污泥溶出破解率为评价指标,通过不同性质的厌氧污泥超声破解实验,探讨不同的污泥性质对厌氧污泥破解效果的影响,为厌氧污泥的下一步隐性生长处理提供良好条件。控制在超声频率为20kHz,超声声能密度1.2 W/mL,超声辐照时间20 min的条件下进行破解实验,实验结果表明,污泥的初始温度、pH值和污泥浓度等参数对厌氧污泥破解效率影响较大。     

Effects of Strength and Position of Pollutant Source on Pollutant Dispersion Within an Urban Street Canyon

A two-dimensional numerical model for simulating airflow and pollutant dispersion inside an urban street canyon was first developed using the FLUENT code, and then it was validated against a wind tunnel experiment. Then the effects of strength and position of pollutant sources on pollutant dispersion within an urban street canyon were investigated numerically. The numerical results showed that the dimensionless pollutant concentrations within the urban street canyon were independent from the source strength. The results also revealed that the pollutant distributions inside the urban street canyon with a two-lane road were influenced significantly by the positions of the two sources: 1) the closer the two sources were to the street center of the canyon, the lower the pollutant concentrations on the leeward wall and at the human respiration level in the leeward footpath became; 2) the pollutant concentrations on the windward wall and at the human respiration level in the windward footpath were not sensitive to the locations of the two sources as long as the source on the windward lane was situated outside the small recirculation zone at the bottom corner of the canyon windward wall; 3) the pollutant concentrations on the lower parts of the windward and leeward walls as well as in the two footpaths increased greatly when the two sources were moved from outside into the small recirculation zones.     

多硼酸盐的分散作用及其对碳酸钙沉淀的影响

采用静态电导率法,研究了不同温度及硼浓度条件下,硼砂和合成的五水合五硼酸钠（SPP）对碳酸钙临界过饱和度值的影响,并利用多晶X射线衍射仪、扫描电子显微镜和能谱仪对碳酸钙沉淀进行表征。结果表明,硼砂和SPP具有分散作用,硼含量越高,分散作用越好。随着温度升高（20~70℃）,硼砂和SPP的分散作用均降低,但SPP更具有耐温性。进一步研究发现,硼砂和SPP能够捕获Ca2+,导致沉淀量减少,同时能够降低碳酸钙结晶度,但是不改变碳酸钙的晶型和成分。SPP的分散作用更明显,导致沉淀中出现球状和盘状结构。这可能是由于SPP溶液中[B5O6（OH）4]-阴离子特殊的三维骨架结构更易捕获Ca2+,阻止沉淀晶粒的生成。研究结果可为高效多硼酸盐分散剂的研发提供依据。     

海底管道泄漏油气扩散规律数值仿真与对比分析

为研究海底原油与天然气单相泄漏扩散规律的差异性,合理制定应急响应策略,减小事故损失,针对海底管道失效所致的原油与天然气泄漏问题,基于计算流体动力学CFD方法,建立海底油气管道泄漏事故后果预测与评估模型,对特定事故场景下的海底原油与天然气泄漏扩散过程进行模拟与分析,从泄漏扩散过程、工况因素影响、泄漏后果及应对策略4个方面对比原油与天然气的泄漏扩散特性。结果表明:相同工况下,海底原油与天然气在泄漏速率、扩散时间、扩散形态及水平最大扩散距离方面存在显著差别;与天然气相比,原油泄漏扩散行为对工况因素具有更高的敏感性;原油泄漏会引发严重的环境灾害,天然气泄漏则会影响海上结构物的稳定性及引发火灾爆炸事故,据此需合理制定具有针对性的应对策略。     

粉尘密度对20 L球罐内粉尘分散规律影响

为分析不同粉尘因密度的差异对20 L球形爆炸装置球罐内粉尘分散过程流场变量变化和点火延迟时间的影响,利用CFD数值模拟的方法,研究了3种不同密度的粉尘在球罐分散过程中湍流动能、流场速度、粉尘浓度3种流场变量在球心处的变化规律。研究结果表明:在其他条件一致的情况下,粉尘密度越小,湍流动能的峰值越小,粉尘云浓度和流场速度的峰值则越大;粉尘密度对湍流动能的增值速率没有影响,而粉尘密度越小,流场速度和粉尘浓度的增值速率越快,粉尘浓度衰减至稳定值的时间也越短。表明粉尘密度越小,点火延迟时间也越小,因此,建议铝粉点火延迟时间在50~60 ms之间,锆粉和锌粉在60~80 ms之间。     

基质固相分散萃取—气相色谱法测定土壤中有机氯农药含量

建立了一种基质固相分散萃取—气相色谱法测定土壤中8种有机氯农药含量的方法,优选了固相分散剂及其用量、洗脱溶剂以及土壤样品与分散剂的质量比。实验结果表明,在弗罗里硅土作为分散剂、正己烷和丙酮（体积比为1∶1）为洗脱溶剂、土壤样品与分散剂的质量比为1∶3的优化条件下,8种有机氯农药在50~250 μg/kg范围内表现出良好的线性关系,相关系数大于0.99,加标回收率为60.3%~94.3%,相对标准偏差为6.83%~8.95%。实际土壤质控样测试结果显示,本方法的测试结果在标准值的不确定度范围内,可满足土壤中有机氯农药残留的检测分析。     

恒定横流底部多孔排放近区污水稀释扩散效果因素研究

借助于人工模型试验，分析了恒定横流底部多孔排放时扩散器设计参数（射流角度、射流速度、喷口个数）、上升管间距）及环境参数（环境水深、环境流速）对污水近区稀释扩散效果的影响，实验结果表明，除了环境条件对污水稀释扩散效果影响明显之外，扩散器设计参数对污水的近区稀释扩散也有显著的影响，针对白龙港排放口水域，喷口射流角度宜控制在１０°左右，喷口个数取１６个     

SBR工艺城市污水处理厂微生物气溶胶逸散特征

在采用SBR工艺的某污水处理厂设置采样点,研究各污水处理工艺段微生物气溶胶的逸散特征.结果表明,各工艺段均有细菌气溶胶逸散,浓度为82～1 525 CFU·m~(-3),粗格栅、生化池和污泥脱水间为主要逸散源.各工艺段检测到的细菌气溶胶主要菌属为Cyanobacteria,其它丰度较高的菌属有Aeromonas、Peptostreptococcaceae、Moraxellaceae、Chroococcidiopsis、Sphingomonas、Arcobacter及Acinetobacter等,其中Aeromonas、Arcobacter、Acinetobacter及Sphingomonas为潜在致病菌.微生物气溶胶的浓度和丰度沿垂直方向和水平方向减少.适宜的温度和相对湿度利于微生物气溶胶在空气中保持活性(P 0. 01),风速则与微生物气溶胶的逸散呈负相关(P 0. 05).污水处理过程产生的微生物气溶胶的暴露风险较小(HQ 1),但是污染物的累积会增加人体的暴露风险.生物除臭反应器在处理臭味气体的同时还可以有效削减微生物气溶胶.