单层开采的圆形定压边界两层油藏压力动态分析

为更好地分析具有越流的多层油藏的压力动态，采用有效井径的概念，在半透壁模型的基础上建立了圆形定压边界、两层越流油藏单层开采时的渗流数学模型。通过拉氏变换得到了拉氏空间中以Bessel函数表示的精确解。数值反演计算结果表明，单层开采的两层油藏与全部打开的两层油藏的压力动态基本相同，都表现为3个阶段：早期是介于两个渗透层之间的均质流动；中间为过渡段，导数曲线出现下凹特征；晚期表现为整个油藏的均质特征。随着边界距离的增加，压力导数值趋近于0．5。半透率越大过渡段出现得越早。导数曲线下凹程度越小；储容比越大导数曲线峰值越小，导数曲线下凹程度越小；随着两层渗透率比值变小。过渡段变短，导数曲线下凹程度变小。图1参9     

横流环境中两孔热水浮射流数值模拟研究

为了达到热废水排放过程中热水快速稀释的目的,采用Fluent中Realizable k-ε模型基于SIMPLEC算法,研究了热射流过程中,射流孔间距、初始流速对射流流场、温度场的影响规律。研究表明:随着射流孔间距的增大,第1孔射流对第2孔射流影响程度逐渐减弱且第2孔射流的弯曲程度随之增加;射流与横流作用促使反向涡对的产生,加快了热水与环境水体的掺混度,横断面温度场出现"肾形"分布;当相对孔间距相同时,随着射流初始流速的增加,第1、2孔射流温度衰减速率随之增大;射流初始流速相同时,射流孔间距的增加对第1孔射流轴线温度稀释度影响较小,对第2孔射流的轴线温度稀释度影响相对复杂;S/D=2时,增大热射流的初始流速,为本研究中热水快速稀释的最优方案。     

气固错流移动颗粒床过滤器压降特性研究

研究了错流移动颗粒床过滤器操作压降与过滤介质特性、表现过滤气速、颗粒层移动速度和床层粉尘沉积量之间的关系。结果表明，无粉尘沉积时，床层压降可以用Ergun方程计算。颗粒层移动速度的变化并不会造成床层压降的显著变化。除尘过程中，床层内粉尘沉积量随气体中粉尘浓度的增大、颗粒层移动速度的减小而增加，同时将导致床层压降的显著增大。错流移动床除尘操作压降可以用带修正项的Ergun方程计算，其修正项为比沉积率和颗粒层空欧率的函数。在实验数据范围内，该方程的计算结果与实验数据最大偏差小于15％。     

同心环管圆孔射流流动特性的数值模拟

采用标准的k-ε模型及混合有限分析法对均匀横流条件下三维受限同心环管中单孔和双孔的横向紊动射流流动进行数值模拟.分别得到单圆孔不同流速比下的射流轨迹线与数学表达式、双圆孔不同间距下的速度场.结果显示：射流比越大,射流深度越深,射流越不容易发生弯曲;射流横断面上速度最大值的偏离程度随横流距离的增加而增大,但增大率越来越小;双孔射流孔间距影响射流轨迹线,由于前一个射流的遮挡作用,后面射流更不容易发生弯曲.     

微滤提纯莲心碱操作条件对膜阻力影响的实验研究

采用十字流微滤方法分离莲子心醇提液中的莲心碱和叶绿素，考察了不同操作条件下微滤过程中各种过滤阻力的大小及其构成情况，分析了影响莲心碱和叶绿素微滤的主要因素，并提出降低膜污染、提高膜过滤速率的改进措施．     

非均匀降膜式气液交叉流除尘系统运行能耗数值分析

气液交叉流(GLCA)除尘系统通过分布板形成阵列液柱群以捕获工业尾气中的颗粒物,尾气颗粒脱除率随液柱群阵列单元排数的增加而增大,但系统运行能耗较高且主要集中于循环水耗.为降低循环液量及运行能耗,提出仅在对颗粒捕获起主要作用的迎风面布膜的非均匀降膜阵列以代替原液柱阵列.采用大涡模拟(LES)和离散相模型(DPM)分别对不...     

超滤陶瓷膜深度处理造纸废水的实验研究

针对当前造纸废水水质特点及深度处理工艺,提出采用超滤陶瓷膜绿色节能工艺对造纸废水开展深度处理实验研究。结果表明,陶瓷膜的最佳工作条件为:跨膜压差0. 2 MPa、进膜流量1000 L/h,在该条件下造纸废水的固体悬浮物(SS)去除率大于94. 5%,化学需氧量(CODCr)去除率大于76. 2%,色度去除率高于72. 3%,水质达到了《制浆造纸工业水污染物排放标准》(GB 3544-2008)要求;膜清洗再生实验结果表明经过反循环化学清洗后超滤陶瓷膜通量可以恢复至90%以上。     

Effectiveness of Cross-Flow Microfiltration for Removal of Microorganisms Associated with Unpasteurized Liquid Egg White from Process Plant

ABSTRACT:  Thermal preservation is used by the egg industry to ensure the microbiological safety of liquid egg white (LEW); however, it does not eliminate all microorganisms and impairs some of the delicate functional properties of LEW. In this study, a pilot-scale cross-flow microfiltration (MF) process was designed to remove the natural microflora present in commercial LEW, obtained from a local egg-breaking plant, while maintaining the nutritional and functional properties of the LEW. LEW, containing approximately 10^{6 ± 1.7} colony forming units (CFU) per milliliter of total aerobic bacteria, was microfiltered using a ceramic membrane with a nominal pore size of 1.4 μm, at a cross-flow velocity of 6 m/s. To facilitate MF, LEW was screened, homogenized, and then diluted (1 : 2, w/w) with distilled water containing 0.5% sodium chloride. Homogenized LEW was found to have a threefold lower viscosity than unhomogenized LEW. Influence of MF temperature (25 and 40 °C) and pH (6 and 9) on permeate flux, transmission of egg white nutrients across the membrane, and microbial removal efficiency were evaluated. The pH had a significantly greater influence on permeate flux than temperature. Permeate flux increased by almost 148% when pH of LEW was adjusted from pH 9 to pH 6 at 40 °C. Influence of temperature on permeate flux, at a constant pH, however, was found to be inconclusive. Microbial removal efficiency was at least 5 log₁₀ CFU/mL. Total protein and SDS-PAGE analysis indicated that this MF process did not alter the protein composition of the permeate, compared to that of the feed LEW, and that the foaming properties of LEW were retained in the postfiltered samples.     

Application of microfiltration to egg white depleted in ovomucin

Summary An attempt was made to reduce the microbial load of unpasteurized fresh egg white by using cross-flow microfiltration and a Tetra-Laval bactocatch installation. Cross-flow tangential microfiltration of liquid fresh egg white was not feasible as there was irreversible membrane clogging within a few minutes of operation. As membrane clogging could have been caused by ovomucin, this protein was removed from whole fresh egg white by increasing the salt strength and lowering the pH. Ovomucin-depleted egg white (ODEW) was successfully microfiltered on the same membrane. Compared to fresh egg white, ODEW had lower foaming and viscous properties, and these properties remained unchanged after bactofiltration. The reduction of microbial load was, however, relatively low.