Behavior of Oil and Gas from Deepwater Blowouts

This paper presents a detailed analysis of different deepwater blowout scenarios using the Clarkson deepwater oil and gas model (CDOG). In CDOG, hydrate formation, hydrate decomposition, gas dissolution, nonideal behavior of gas, and possible gas separation from the main plume due to strong cross-currents, are integrated with the jet/plume hydrodynamics and thermodynamics. CDOG takes into account unsteady-state three-dimensional variation of ambient currents and density stratification. Detailed comparisons between CDOG simulations and deepspill field experiments have been published. The model is used to simulate 30 deepwater blowout scenarios based on realistic cases and the results are analyzed in this paper. The scenarios demonstrate the differences in plume behavior due to different ambient conditions, different types of gas, possible hydrate formation, and variations in gas-to-oil ratio. Some key findings of these analyses follow. Oil droplet sizes affect the oil surfacing time significantly. For oil-only blowouts, the ambient conditions do not affect the oil surfacing time significantly, but the location and the size of the slick are affected. For oil and gas mixes, the surfacing time is not sensitive to the type of gas in the mix, but is somewhat dependent on the ambient conditions. In none of the cases simulated here, did free gas reach the water surface. While changing the release temperature had only an insignificant effect on the model results, changing oil type or gas-to-oil ratio did affect the model results. The analyses are useful to engineers/scientists and administrators.     

Characterization of the Flocculation Process from the Evolution of Particle Size Distributions

A flocculator-imaging system was developed to characterize the dynamics of particle size distribution (PSD) during flocculation. The system consisted of a flocculator coupled with an external flow-through cell for observation and photography, a microscopic charge-coupled device video recorder with backlighting, and an image analyzer. This nonintrusive side-stream setup was used to record the evolution of the PSD to determine the flocculation dynamics of three types of particle systems: Clean kaolin, kaolin coated with natural organic matter (NOM), and the kaolin/NOM system after ozonation. In addition to the PSD measurement, the ζ potential, NOM reduction, and turbidity removal after the jar test of flocculation and sedimentation were determined for the particle systems at various alum dosages. The results of the ζ-potential analysis and the PSD measurement indicated that flocculation takes place rapidly to form highly porous aggregates when the particle surface charge is fully neutralized. The adsorption of NOM on the particle surface stabilized the particles considerably, and thus hindered the flocculation process. Sweep flocculation using a much higher alum dosage was an effective means of process enhancement for the removal of particulates and associated organic matter. Ozonation of the kaolin/NOM solution, however, did not appear to have any positive effect on particle destabilization and flocculation. It is argued that ozonation produced more acidic functional groups in the NOM on kaolin, which increased the surface charge density and hence the stability of the particles in softer water.     

Size Distributions and Light Scattering Features of Minerogenic Particles in a Stream during Runoff Events

Inorganic (minerogenic) particles received from streams during runoff events cause undesirable increases in turbidity (Tn; i.e., the light scattering coefficient, b) in many lakes and reservoirs. Quantification of particle inputs in the context of turbidity impacts and representative light scattering calculations (submodel), the necessary components in the development of a mechanistic multiple particle class model to simulate these impacts, are described for Schoharie Creek, N.Y. Light scattering attributes of minerogenic particles, including number concentration (N), size distribution (PSD), composition, and projected area per unit volume (PAVm), are quantified for three runoff events through analyses by scanning electron microscopy interfaced with automated X-ray microanalysis and image analysis (SAX). The combined credibility of the light scattering submodel and SAX to represent the light scattering features of minerogenic particles is depicted by the consistency of calculated scattering efficiencies with theory and the strength of the reported Tn-PAVm relationship. Particles in the size range of 2–10?μm were responsible for b and Tn in the stream, with greater contributions by the larger particles of this range at elevated stream flows. Empirical relationships are developed to predict N and PSD from Tn or stream flow.     

Bubble Sizes, Breakup, and Coalescence in Deepwater Gas/Oil Plumes

Bubble size distribution (BSD) plays a major role in transport and fate of gas or oil released in deepwater. However, no reliable method is available to estimate gas or oil BSD after a deepwater spill. Breakup and coalescence have been identified as key processes controlling BSDs in turbulent jets. The present work introduces bubble breakup and coalescence processes for deepwater gas or oil spill models. A population balance equation representing bubble volumes is used to model the evolution of bubble sizes caused by breakup and coalescence. Existing theories for bubble breakup and coalescence rates in bubble columns are adopted to deepwater plumes. The advantage of the present model is that the BSD is generated as a result of breakup and coalescence; and therefore, a predefined BSD is no longer necessary for simulations. The comparison of model-computed results with laboratory and field data shows a good agreement. Scenario simulations show that the seed diameter given to start computations affects only for a short distance from the release point. Simulations also show that bubble breakup and coalescence is important only during the early stages of the plume where turbulence is dominant. The importance of accounting for gas bubble breakup and coalescence in estimation of gas dissolution is also demonstrated.     

Hydrophobicity and Molecular Size Distribution of Unknown TOX in Drinking Water

The analysis of total organic halogen (TOX) in drinking water indicates that a substantial amount of the halogenated compounds cannot be accounted for by known specific disinfection by-products (DBPs). The primary aim of this research was to characterize the hydrophobicity and molecular size distribution of the unknown halogenated DBPs using XAD resins and ultrafiltration membranes. The impact of membrane rejection on the size analysis of unknown TOX was also investigated using chlorinated fulvic acid. Six finished waters from different locations and treatment processes were collected and fractionated into various hydrophobicity and molecular size groups. The results showed that most unknown TOX was in the size range between 0.5?kDa and 10?kDa, but it could have a wide spectrum of hydrophobicities. Simple ultrafiltration was not always reliable as a characterization tool, as it was shown to reject a significant fraction of DBPs with molecular weight (MW) lower than the membrane cutoffs. Flushing with deionized water was effective in removing these low MW compounds from the ultrafiltration cell. A significant reduction in the apparent size of unknown TOX resulted when low MW DBPs were flushed out of the cell (comparing with classic parallel ultrafiltration). Coagulation of fulvic acid also significantly reduced the apparent size of unknown TOX formed by chlorine.     

Modeling Uncoupled Solute Transport in Natural Organic Matter Size Fractionation by Ultrafiltration

Physicochemical separation of organic macrosolutes and colloidal particles is routinely required during the analysis of natural, waste, and process waters derived from aquatic and terrestrial environmental samples. This study was conducted to demonstrate the utility of a two-parameter nonlinear permeation coefficient model (PCM) in describing the uncoupled transport of solutes in dilute heterogeneous solutions subjected to batch ultrafiltration (UF). The PCM was used in conjunction with natural organic matter (NOM) permeate data for a natural water and six hydrophobic and hydrophilic subfractions to determine permeation coefficients p and NOM concentrations Cr0 with apparent molecular weight less than membrane specific cutoff values of moderately hydrophilic YC/YM series Amicon? UF membranes. Experimentally measured permeation coefficients p determined for the whole water were found to correlate well with composite permeation coefficients p? calculated using a mass-fraction weighted average of individual NOM subfraction permeation coefficient values. Correlation of experimentally measured and calculated permeation coefficient values (p and p?) indicated that the PCM can adequately describe uncoupled transport of chemically distinct solute fractions during batch UF of heterogeneous dilute solutions.     

铝酸钠(钾)溶液种分过程的粒度研究

采用间歇式反应器,研究了52 5℃,COH-=5 16mol/L,αk分别为1 45、1 55、1 65的纯铝酸钠和铝酸钾溶液种分过程的晶体粒度分布(PSD)规律。结果表明,在相同的分解条件下,铝酸钠和铝酸钾溶液中晶体的粒度分布随时间的变化有一定差异。铝酸钠溶液PSD曲线的主粒度峰的位置总在铝酸钾溶液的上方;最显著的差异是在分解16h后,铝酸钾溶液的PSD曲线在10～44 774μm处有一个显著的突起峰,而铝酸钠溶液则没有。不同αk的铝酸钠和铝酸钾溶液,这种粒度分布随时间变化的差异相似。     

真空气雾化参数对粉末粒度及形貌的影响研究

对雾化压力、雾化气体温度等雾化参数对粉末粒度、形貌的影响进行了研究。试验结果表明,雾化压力在2.3~3.2MPa范围内对粉末粒度影响不大,当雾化压力超过3.5MPa时,粉末粒度开始变细小。雾化气体温度对粉末粒度影响最大,较高的雾化气体温度有利于获得较细小的粉末。     

Particle Size Distribution in Highway Runoff

Particles in highway runoff contain various sorbed pollutants, and many best management practices (BMPs) are selected for particle removal efficiency, which makes particle size distribution a crucial BMP design parameter. Particles between 2 and 1,000?μm in diameter were quantified for three rainfall events during the 2002–2003 rainy season at three highway sites in west Los Angeles. Rainfall, runoff flow rate, and a large suite of water quality parameters were also measured. An experimental protocol was developed for bottle cleaning, sample storage, and mixing that provided repeatable results. Particle aggregation occurred which required samples to be analyzed in less than 6?h; the concentration of small particles decreased with a corresponding increase in the concentration of larger particles in stored samples. The particle concentration decreased as the storm progressed and the number of large particles decreased more rapidly than the total number of particles. Particles demonstrated a strong first flush. On average, 40% of the particles were discharged in the first 20% of the runoff volume.     

库尔特激光粒度分布仪在测定钽铌复合物粒度分布中的应用

文章介绍了应用库尔特激光粒度分布仪测定钽铌复合物粒度分布的方法。钽铌复合物颗粒均匀分散在二次去离子水中,以一定的流速通过激光束。衍射光经透镜被光电探测器接收转化为电信号,由此测出颗粒的粒度分布,并讨论了应用中的经验。该方法容易建立,精密度高,能够给出多种粒度分布结果以及参数,非常适合生产过程中的应用。     

Role of Slip Velocity in the Behavior of Stratified Multiphase Plumes

This paper presents direct measurements of multiphase plumes in stratification and correlates characteristic plume properties with the nondimensional slip velocity UN. UN is defined as the ratio of the bubble slip velocity us to a characteristic plume fluid rise velocity (BN)1/4; B is the total kinematic buoyancy flux, and N is the buoyancy frequency. UN is derived by dimensional analysis and is compared to other nondimensional parameters for multiphase plumes in the literature. To investigate correlations of the nondimensional numbers with plume properties, laboratory experiments were conducted in linear stratification using dispersed phases of air, oil, and glass beads (creating an inverted plume). A new type of plume behavior is identified, called Type 1*, in which the horizontal motion in the first detrainment event disperses the relatively weak bubbles, creating a diffuse bubble plume that forms out of the intrusion. Measurements from these and previous experiments for type behavior, trap height, and intrusion layer flux are presented. Measurements are also presented for the new parameters peel height, mass fraction of passive tracer peeled, and bubble spreading ratio. The results show that correlations with the single parameter UN, which replaces other two-parameter models, are successful.     

采用电解+激光粒度分析仪检测钢中的夹杂物

 采用电解中型试样+激光粒度分析仪的方法,测定了钢中粒径为1~100μm夹杂物的尺寸分布,填补了粒径为20~80μm夹杂物尺寸测定的空白。发现IF钢粒径为1~100μm的夹杂物中SiO2类夹杂物所占比例较高,并且正常坯夹杂物中粒径大于30μm的夹杂物所占的比例可达4. 25%,这对冷轧板的表面质量存在极大的威胁。     

选矿流程考察中各粒级产率准确性的验算方法

针对选厂考察过程中选矿产品粒级产率出现偏差,难以确定样品数据准确性等问题,提供了一种简便且实用的验算方法,可通过产品各粒级产率的分布关系,从而确定样品数据的准确性及其对应的产率,为选矿技术人员用于查找工艺考察数据误差来源,判断日常工艺流程考察中数据的准确性提供了依据。     

Dynamic Characteristics of Particle Size Distribution in Highway Runoff: Implications for Settling Tank Design

To understand the characteristics of particle size distribution (PSD) in highway runoff and to facilitate designing best management practices, PSD (2–1,000?μm) was monitored in seven rainfall events in the 2002–2003 rainy season at three highway sites in west Los Angeles. Most of the particles in number were less than 30?μm in diameter and more than 90% were less than 10?μm. Particle number concentration decreased rapidly to 6?mm of accumulated rainfall and then declined more slowly throughout the storm. Particle number concentration was correlated with total suspended solids (TSS) and turbidity. Grab sample particle median diameter increased with increasing TSS. A two-compartment settling tank was evaluated using the measured PSD and was effective in removing both small and large particles. Capturing and retaining the first 20% of the runoff volume on seasonal average can remove 40% of the total particulate load based on calculated particle mass. Using literature data for metal concentrations sorbed to particles, this size holding compartment coupled with a similar size continuous flow clarifier can achieve 65–90% removal for the metals investigated.     

Stability of the Dividing Distribution Function Method for ParticleSize Distribution Analysis in Small Angle X－Ray Scattering

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Distribution of Particulate-Bound Metals for Source Area Snow in the Lake Tahoe Watershed

The porous matrix and long residence time of snow in traffic corridors can result in the accretion of particulate matter (PM) and metals. This temporary repository contributes PM-based and dissolved metals to surrounding environs during snowmelt. This study focused on distribution and settling of PM-based metals (Al, As, Cd, Cr, Cu, Fe, Pb, and Zn) in snow. Snow was sampled from six sites during four winter seasons. PM-based metals are examined herein as a function of PM granulometry, specifically particle-size distributions (PSDs) and PM surface area. Cumulative metal mass distributions across each PSD are modeled as gamma functions. Results indicate Al (15 g/kg) and Fe (4.2 g/kg) are the highest PM-based concentrations; Cd (0.18 mg/kg) and As (4.9 mg/kg) are the lowest. The PM size (d50?m) associated with the median metal mass ranges from 179 to 542?μm. The constitutive gamma results are integrated with Hazen’s settling algorithm to model PM-bound metal separation for a sedimentation basin at a local snow storage site. Flows are modeled in the storm water management model (SWMM) from snowmelt and historical rainfall time series. Results indicate that Type I sedimentation is capable of separating the sediment fraction (>75?μm) and majority of metal mass. While the basin is effective at separation of coarser PM-based metals, additional practices such as pavement and drainage appurtenance cleaning, as well as adsorptive-filtration can further manage suspended PM and metals, as well as dissolved metals.     

Particle Image Velocimetry Measurements of the Mean Flow Characteristics in a Bubble Plume

A direct measurement method for the velocity field in multiphase flows using the particle image velocimetry (PIV) and particle tracking velocimetry (PTV) methods is developed to study the flow characteristics of an unbounded bubble plume in quiescent, unstratified ambient conditions. A single camera is used to obtain images containing both bubbles and fluid tracer particles. Using gray-scale thresholding, phase-separated images of the bubbles are produced, and bubble velocities are obtained from these images using the standard PTV method. Regular PIV is applied to the mixed fluid images, and bubble vectors are removed using a velocity threshold and vector median filter that is calibrated to the PTV result. From the separate velocity fields, the time-averaged flow characteristics of a bubble plume are studied. Gaussian velocity profiles match the entrained fluid velocity, and top-hat velocity profiles match the bubble velocity. Time-averaged values are also presented of velocity, plume width, entrained fluid volume flux, and void fraction as a function of height. From these data, the entrainment coefficient for the entrained ambient fluid is calculated and lies between 0.08 near the plume source and 0.05 in the upper reaches. The results for the entrainment coefficient, together with those from the literature, are correlated to a nondimensional velocity, given by the ratio of the bubble slip velocity us to a characteristic velocity in the plume (B/z)1/3, where B = kinematic buoyancy flux and z is the height above the source.