基于死端过滤的微滤过程定流量控制

本文针对处理行业中应用广泛的基于死端过滤微滤过程 ,利用模糊控制和 PD控制 ,探讨了这类设备的定流量控制问题。实际中取得了较好的控制性能。     

陶瓷膜构型对错流微滤酵母悬浮液性能的影响

采用3种构型的陶瓷微滤膜元件对酵母悬浮液进行错流过滤实验,考察陶瓷膜元件的构型对于其错流过滤性能的影响。结果表明:减小陶瓷膜元件的通道直径可以提高料液在膜表面的剪切力,有助于提高过滤稳定通量和临界压力,在3 m/s膜面流速、0.1 MPa跨膜压差条件下,单管、19通道、55通道的稳定通量分别为96、128、196 L/(m2.h);在3 m/s膜面流速条件下,3种陶瓷膜元件的临界压力分别约为0.15、0.2、0.2 MPa。另外,减小通道直径还可以减小滤饼层的比阻,有利于降低过滤阻力;与提高膜面流速来增大过滤通量的方法相比,减小陶瓷膜的通道直径具有能耗较小的优点。     

操作条件对微滤膜通量的影响

在自制的搅拌死端微滤膜装置上,研究了不同搅拌速率（400、600,800,1000和1200r／min）、不同温度（20、25,30、40和50℃）、不同操作压力（0．04、0．06、0．08、0．10、0．12和0．14MPa）和不同浓度的酵母悬浮液（0．1、0,25、0．5、1、2和3叽）对膜通量的影响,并利用多元线性回归模型,在标准化影响因子分析法的基础上进一步研究和分析了操作条件对膜通量的影响程度。研究结果表明：在压力为0．04～0．10MPa范围内,搅拌速率（∞）、温度（r）、操作压力（P）、浓度（G）对膜通量都具有显著的影响,各操作条件对膜通量的影响程度的大小顺序为：搅拌速率〉温度〉压力〉浓度,且各自所占的比例分别为64．9％、14．4％、12．9％和7．8％,同时通过多元线性回归得到了膜通量与不同操作条件间的回归方程为：J=-1．804×10^-7＋3．149×10^-5p＋3．526×10^-7-2．573×10^-6C＋1.388×10^-8ω,从而为搅拌死端微滤过程的优化提供了依据。     

悬浮液体系错流微滤过程研究

对悬浮液体系的错流微滤（ＣＦＭＦ）过程进行理论分析和实验研究，探讨了料液类别、浓度、循环流速及操作时间、压力等参数对ＣＦＭＦ性能的影响。建立了稳态ＣＦＭＦ过程的简化组合模型，对过程的计算具有现实意义。     

超声强化多通道陶瓷膜微滤超细TiO2悬浮液

针对超声强化膜分离过程能耗高的问题,提出并设计了一种新型超声强化膜分离操作方式,并进行了超声强化陶瓷膜微滤超细TiO₂颗粒悬浮液的研究。考察了超声场参数、操作时间及溶液环境对多通道陶瓷膜微滤过程的影响规律,并分析了此操作方式强化陶瓷膜微滤颗粒悬浮体系的机理。结果表明,该操作方式能够获得较高膜通量恢复率及平均膜通量,同时超声能量消耗减小了90.0%以上;降低超声频率及提高功率,有利于膜通量恢复,在超声参数45 kHz和0.33 W·cm^-2条件下,膜通量恢复到初始值的94.0%;控制超声辐射时间0.167 min,微滤时间8 min时,平均膜通量提高了61.5%;降低悬浮液颗粒浓度及提高料液温度都有利于超声场强化陶瓷膜微滤过程。     

颗粒粒径和膜孔径对陶瓷膜微滤微米级颗粒悬浮液的影响

通过测定颗粒悬浮液通过陶瓷微滤膜时的参透通量及污染阻力,确定了陶瓷膜处理微米级颗粒悬浮液时,颗粒粒径和膜孔径对微滤过程的影响和膜污染机理,获得了微米级颗粒悬浮液微滤过程中膜孔径的选择方法。     

活性炭吸附甲基橙模拟废水预测模型研究

分别采用BP人工神经网络算法及多元线性回归法,以实验所得的36组数据为样本,建立了以吸附时间、活性炭投加量及甲基橙废水浓度为输入变量,以活性炭吸附处理后甲基橙溶液的吸光度为输出变量的吸附预测模型,并进行了两模型预测效果的对比。结果表明,BP神经网络模型获得了比多元线性回归更好的拟合预测效果。使用BP神经网络模型可以实现同时考虑三个操作因素条件下活性炭吸附特性的预测,而且预测结果与实验数据吻合度较高,其预测样本最大和最小相对偏差分别为2.92%和0.029%,残差绝对值小于0.050 5。     

硅藻土微滤复合膜的制备工艺研究

本文以α-Al2O3微滤膜为载体,采用浸渍法在其上涂覆一层硅藻土制备硅藻土微滤复合膜,重点探讨了复合膜的制备工艺。实验表明,该硅藻土复合膜在低温下煅烧,可在反冲洗下将硅藻土剥离,从而实现载体膜的重复使用。     

气液两相流在炭膜微滤钛白悬浮液中的应用研究

采用平均孔径为1.0μm的管状多孔炭膜实验研究了炭膜微滤钛白悬浮液的过程中引入气体形成两相流的强化微滤过程.实验结果表明,在温度20℃、跨膜雎差0.04～0.16 MPa、料液流速0.85～1.56 m·s-1、气体流速0.29～2.02 m·S-1、悬浮液浓度0.1～1.0 g·L-1时,通入气体形成的气-液两相流可以大大强化微滤过程.两相流相对于单相流的最大稳定渗透通量可提高62%,而且达到稳定通量的时间也相应缩短.实验发现,在相同操作条件下膜组件竖直放置比水平放置时稳定渗透通量增加了12%;弹状流是有利的强化流型:两相流条件下随着跨膜压差的增加,稳定通量快速增加,在压力0.11 MPa 时通量达到最大值,然后随压力增加,渗透通量缓慢下降.     

动态过滤的过滤比阻研究

从理论分析入手，讨论了影响滤饼比阻大小的因素，并结合因次分析法得出动态过滤条件下比阻的准数关联式。结合实验数据，推导出本实验条件下立得粉的滤饼比阻关联式。     

Modeling of fouling in cross-flow microfiltration of suspensions

Cross-flow filtration of fine suspensions through microsieves occurs in microprocessing. The interaction of particles with surfaces in microenvironments has been extensively studied, but predominantly in monolayers and not with an eye to microfiltration. Here, we introduce a microfiltration model that pertains to particles that might be seen as fine in a macroscopic environment, but are large enough to intrude significantly into the shear layer of a microchannel. Thus, particle accumulation upon the sieve couples the steady-state filtrate flux and the suspension flow through the microchannel that feeds the sieve. We envision and create a stable, stationary multilayer of particles whose thickness is shear-limited and we identify and verify the structure and parameters that limit steady filtration in this environment. At first, a packed bed of particles forms, growing into and regulated by the micro channel's shear flow. A critical shear stress is shown to determine the thickness of the bed, seen as a stationary and stable multilayer of particles through which filtration may occur. As the bed thickens, at the expense of channel area for suspension flow, surface shear stress increases until no further particle adherence is possible. We built a simple example using hard noninteracting polymer microspheres and conducted cross-flow filtration experiments over Aquamarijn™ microsieves (uniform pore size of 0.8 μm). We observed a steady cake-layer thickness and because of the simple geometry afforded by uniform spheres, we could approximate the force balance, cake resistance, and filtration rate from first principles. The good fit of our data to the proposed mechanism lays a firm basis for the semiquantitative analysis of the behavior of more complex suspensions. © 2018 American Institute of Chemical Engineers AIChE J, 65: 207–213, 2019     

多元线性回归优化聚偏氟乙烯/乙酸纤维素共混微滤膜成膜因素

首先分别以纯水通量、平均泡点压力减最大泡点压力、纯水通量加最大泡点压力减平均泡点压力作为考察PVDF/CA共混微滤膜的性能指标,设计了9因素4水平的正交实验表L₃₂(4⁹)并进行实验,其次采用标准化系数矩阵的多元线性回归模型对实验数据进行处理。结果表明：当以纯水通量为目标函数时,共混比、固含量、添加剂含量、凝胶浴温度是影响因子;当以平均泡点压力减最大泡点压力为目标函数时,固含量是影响因子;当以纯水通量加最大泡点压力减平均泡点压力为目标函数时,固含量是影响因子。结合环境扫描电镜照片对实验结果的综合分析后确定,当共混比、固含量、添加剂含量和凝胶浴温度分别为4∶1、12%、2%～3%和30～35℃时,即可制得性能较好的PVDF/CA微滤膜。     

Effect of addition of amino acids on microfiltration behavior of a microorganism slurry

The effect of the addition of amino acids on the microfiltration behavior of Escherichia coli (E coli) and Corynebacterium glutamicum (C glutamicum) slurry was examined using a dead‐end microfilter. It was found that the average specific filtration resistance, α_av, of a slurry of microorganisms increased markedly by adding amino acids. Amino acid concentration ranged from 110 to 876 mol m^?3. However the same concentration of ammonium chloride did not increase α_av. The cells were found to disperse in the presence of lysine, and this caused an increase in α_av. In the case of kaolin slurry, α_av was not affected by adding amino acids. Copyright © 2004 Society of Chemical Industry     

Characteristics of microfiltration of suspensions with inter‐fiber two‐phase flow

Injecting air into hollow fibers and tubular membranes has been proved to be effective in order to control flux decline caused by concentration polarization and particle deposition. This paper presents a study of the characteristics of filtration with inter‐fiber two‐phase flow. The enhancement of flux by bubbling, the effect of the total superficial velocity and gas and liquid velocities, the effect of fiber spacing and orientation, and the concept of critical flux were investigated. A specially designed crossflow hollow fiber cell connected to a light microscope and video‐camera system has been used to monitor particle deposition on the fibers. The results showed that injecting air could enhance the permeate flux and control the deposition of particles on the membrane fibers. Changes in the hydrodynamics of two‐phase flow considerably affected the filtration resistance caused by reversible fouling but was ineffective for the resistance caused by irreversible fouling. The extent of deposition was mainly controlled by the flux level in the range of wall shear rates examined. A critical flux of about 10 dm³ m⁻² h⁻¹ was identified through direct observation of particle deposition on fibers. This value correlated with the flux at which the irreversible fouling became negligible. These results should be significant for optimizing the operation of submerged membrane bioreactor wastewater systems in which bubbling is used as a hydrodynamic technique to improve the performance of the membrane process. © 2000 Society of Chemical Industry     

Limiting flux in microfiltration of colloidal suspensions by focusing on hydrodynamic forces in viscous sublayer

Cross‐flow microfiltration tests were performed on colloidal suspensions under turbulence conditions. By changing the particle diameter, flow rate, and channel height in the membrane housing to measure limiting fluxes, the influence of each parameter on the limiting flux was assessed from the viewpoint of hydrodynamic forces exerted on a particle in the viscous sublayer. In analyzing all the data taken, the particle Reynolds number calculated from the limiting flux is proportional to the 1.5 power of that calculated from the flow rate at the boundary between the viscous sublayer and the intermediate layer. This fact indicates that the limiting flux can be determined in situations where the drag force exerted by the flux is balanced by the lift force in the viscous sublayer. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1760–1765, 2018     

基于BP神经网络的焦炭质量预测

分析了配煤炼焦中影响焦炭质量指标的各种因素及传统焦炭质量的预测方法。以天津天铁焦化厂的配合煤及生产焦炭的各项实际数据为基础,在MATLAB环境下,进行了基于BP神经网络对焦炭质量预测的方法研究。实验结果显示:3种网络的误差基本相同,范围在2%～0.05%,以中间层为15个神经元的略好,满足焦炭质量的预测要求。     

Experimental study on the enhancement of yeast microfiltration with gas sparging

Gas‐sparged microfiltration experiments with baker's yeast suspensions were performed using a 0.15 µm PCI multi‐tubular membrane module. The permeate flux and the enhancement from gas sparging were measured over the following operational parameter ranges: yeast suspension concentration 0.01–10% (wt), transmembrane pressure 0.5–4.0 bar, liquid crossflow velocity 0.36–1.8 ms^?1, gas superficial velocity 0.18–1.02 ms^?1. It was demonstrated that injecting air to create a gas–liquid two‐phase crossflow operation can significantly increase the permeate flux. The observed enhancement, resulting from injecting a relatively small amount of gas with a superficial velocity of 0.18 ms^?1, ranges from 10% when fouling is insignificant to 135% when fouling tendency is severe. Controlled pulse injection leads to further increase in permeate flux. Examining the dependence of permeate flux on transmembrane pressure, it is clearly demonstrated that the injection of gas will elevate the value of the limiting flux. There is also evidence to show that the value of critical flux is increased when gas injection is applied. Further quantitative analysis will be performed in our future work. © 2001 Society of Chemical Industry     

汽车活塞销表面纳米复合镀层的制备及耐磨性预测

在汽车发动机活塞销表面制备Ni-ZrO_2纳米复合镀层,以期提高活塞销表面的耐磨性。通过正交试验,得到影响纳米复合镀层磨损量的因素主次顺序,并在正交试验基础上建立BP神经网络模型,对纳米复合镀层的磨损量进行预测,进而评价其耐磨性。研究表明:BP神经网络模型能用于预测纳米复合镀层的磨损量,磨损量的预测值与实验值具有较高的拟合度。通过正交试验与运用BP神经网络模型优化的最佳参数组合相同,采用最佳参数组合制备的纳米复合镀层的磨损量较低(仅为4.26mg),其耐磨性良好。