板式换热器黏液形成菌与CaCO3混合污垢实验

为了探究黏液形成菌（SFB）与CaCO₃混合污垢在板式换热器（PHEs）中的成垢规律,对不同浓度的CaCO₃与黏液形成菌混合进行了实验研究。结果表明：混合污垢中,黏液形成菌微生物污垢占成垢的主要地位。微生物污垢的热阻渐近值最大,混合污垢的热阻渐近值介于微生物污垢的热阻渐近值和CaCO₃污垢热阻渐近值之间,CaCO₃污垢热阻渐近值最小。这不同于以往得到的混合污垢之间相互促进的结论,说明CaCO₃对黏液形成菌存在抑制作用。维持其他条件不变,随着CaCO₃浓度的增大,混合污垢热阻值随之减小。反之,随着黏液形成菌浓度的增大,混合污垢热阻值随之增大。     

聚偏氟乙烯超滤膜亲水改性研究进展

膜污染会缩短超滤膜的使用寿命,增加由于水力清洗、化学清洗以及膜组件更换而产生的费用。为减少运行成本,有必要对膜污染加以控制。膜污染与原水中污染物的性质和膜本身的性质密切相关。亲水性膜具有水通量高、抗污染性能好的特点,因而提高超滤膜的亲水性是提高膜的水通量和控制膜污染的重要方法之一。简要介绍了具有良好化学稳定性、耐辐射性、耐热性的聚偏氟乙烯膜的表面亲水改性和共混亲水改性的研究进展,指出通过不同的改性方式,聚偏氟乙烯膜都能够实现亲水性的增强。     

电磁场对循环冷却水微生物污垢及水质参数的影响

基于污垢热阻监测实验台,考察了电磁场作用下换热器微生物污垢形成过程典型水质参数的变化,并用灰色关联分析法探讨了水质参数与污垢热阻的关联性。结果表明:在电磁场作用下,细菌数、污垢热阻、浊度较未加磁的对照组低,而p H、电导率较未加磁的对照组高。灰色关联分析显示水质参数与污垢的形成密切相关,其中,浊度对污垢热阻影响最为显著。     

Exploration of alternative models for the aging of fouling deposits

The effect of fouling in heat‐transfer devices (HTDs) is complicated by aging of the fouling deposits. Aging is, like deposition, often sensitive to temperature, so that heat transfer, deposition, and aging are coupled phenomena. Ishiyama et al. (AIChE J. 2010;56:531–545) presented a distributed model of the aging of deposits formed by chemical reaction fouling and illustrated its effect on thermal and hydraulic performance of a HTD operating in the turbulent flow regime. Two‐layer models, simpler than the distributed model, are explored. The deposit is considered to consist of two layers, fresh and aged; this simple picture is shown to be sufficient to interpret thermal and hydraulic aspects of deposit aging when HTDs are operated at constant heat flux (as reflecting laboratory experiments) but not in cases where the constant wall temperature approximation is more realistic. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Impact of deposit ageing on thermal fouling: Lumped parameter model

The thermal and hydraulic performance of heat exchangers can be seriously impaired by the formation of fouling deposits on the heat transfer surfaces. The thermal effect of fouling can be complicated when the deposit is subject to ageing, represented here as a change in deposit thermal conductivity (but not thickness) over time. In this article, we revisit the ageing concept for crude oil fouling proposed by Nelson (Refiner Nat Gas Manufacturer. 1934;13:271–276, 292–298), using a numerical model incorporating first order kinetics to generate quantitative comparisons of different ageing rates. Results are reported for lumped parameter systems (which also simulate point measurement methods commonly used in laboratory testing) that demonstrate that ageing can have a substantial influence on the rate of heat transfer and hence on the surface temperature and rate of fouling. Rapid ageing (compared with the rate of deposition) does not pose problems, but slow ageing, or the use of constant heat fluxes in experiments, can lead to modified thermal fouling behavior. It is concluded that deposit ageing dynamics should be considered alongside deposition rate dynamics when interpreting experimental fouling data and when modeling fouling behavior in support of heat exchanger design or operation. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

水质参数与板式换热器结垢的关联

采用在线监测和手工分析相结合的方法,突出研究了天然循环冷却水（松花江水）中铁离子、细菌总数、pH值、溶解氧、浊度、电导率等水质参数与板式换热器内冷却水污垢热阻的关系。结果表明：板式换热器冷却水污垢热阻值比TEMA标准值小,且不存在诱导期;pH值和溶解氧影响铁腐蚀速率和细菌总数的变化,而浊度和电导率的变化又受细菌总数的影响;它们在运行初始阶段对结垢特性影响较大,而后进入平缓期。混合污垢间存在协同效应,减小溶解氧和细菌总数的含量可以起到抑制结垢的目的。     

污垢热阻实时预测模型校正与应用

针对热阻法污垢热阻预测模型在操作条件变化较大时存在很大的原理误差,不能用于污垢实时监测的问题,提出了一种对热阻法污垢热阻预测模型的校正方法。实验研究表明,校正模型原理误差小于3.5%。并针对热学法污垢热阻测量误差与结垢程度有关的特点,推导了测量误差计算式,提出测量误差实时跟踪的测量方法,依据误差值判断测量结果的有效性,提高对高污垢热阻阶段监测结果的可靠性。应用于煤油冷却器的实时监测,表明测量可靠。     

微纳米气泡控制膜污染研究进展

膜污染是阻碍膜分离技术大规模推广应用的主要问题之一,膜污染控制技术一直都是膜科学领域的研究热点.其中,基于气液两相流的膜污染防控技术已经得到了诸多研究和广泛应用.微纳米气泡因其不同于普通大气泡的独特物理化学性质,近年来在各个领域被广泛关注,而微纳米气泡控制膜污染的研究也日益活跃.文中综述了气液两相流控制膜污染技术的相关...     

Fouling Detection in an Optically Accessible Microstructured Heat Exchanger

The application of highly effective microstructured devices in continuous production and industrial environments is frequently prone to fouling. A new method is presented to characterize fouling in these microstructures. Thermal fouling of aqueous solutions containing whey protein were used as a test system. Different fouling effects could be observed and distinguished. Integral fouling indicators, such as thermal fouling resistance and pressure drop, as conventional criteria for the occurrence of fouling were compared with direct local optical observation. Low thermal fouling resistances could be detected.     

稠油开采污水蒸发结垢过程传热传质计算方法

蒸发器是一种根据热法脱盐原理,利用稠油热采地面系统废热驱动,实现污水脱盐软化,进而回用锅炉实现水资源循环利用的装置。但是,由于油田污水水质的特殊性,使得其极易在蒸发器表面发生结垢行为。通过对污水水质分析,得出其结垢类型主要为碳酸钙垢。建立了碳酸钙垢在强制对流传热和过冷流动沸腾情况下于换热表面结垢的传热传质模型,计算了污水在蒸发过程中析晶污垢形成的数量,得出了与实验数据符合较好的计算模型。对稠油污水在蒸发器中的结垢情况可以进行较好的预测,并对安全生产和设备高效利用有一定参考价值。     

Development and evaluation of vipertex enhanced heat transfer tubes for use in fouling conditions

Heat transfer enhancement is important in the development of high performance thermal systems. Some enhanced tubes that are currently on the market are vulnerable to fouling. Economic and technical problems associated with fouling in process systems have been previously discussed in literature; however, they still require additional examination. Parameters that influence fouling include: surface geometry, surface temperature, surface material/finish, fluid dynamics, flow velocity and fluid properties. Vipertex? enhanced surfaces are optimized process surfaces that increase heat transfer through a combination of factors that include: increasing fluid turbulence, secondary flow development, disruption of the thermal boundary layer and increasing the heat transfer surface area. Vipertubes? that have been exposed to a fouling environment produce more heat transfer than smooth tubes exposed to the same fouling conditions; additionally there was less total fouling over a given time period. The reduction in the rate of fouling is the result of secondary flow patterns that form as a result of the patented Vipertex surface design. These secondary flows circulate near the tube surface and clean it; slowing down the buildup of materials. Vipertex EHT series tubes enhance heat transfer (even under fouling conditions), minimize operating costs and recover more energy than smooth tubes under the same conditions. These surfaces provide an opportunity to advance the design of various heat transfer products.     

高频电磁场抑垢效果的实验研究

用高频电磁法进行换热设备的抑垢处理,具有应用方便、投资小、无污染等优点,是一种极具发展前景的应用技术。但有效评价高频电磁场在线抑垢效果的策略及手段还很欠缺。基于污垢热阻值的在线监测技术,通过自主研发的在线监测评价实验系统采集和处理模拟换热器中研究管段的流体出入口温度、流速和壁温,得到加磁处理与未加磁处理的污垢热阻变化趋势以及加磁处理的抑垢率。同时测量和分析了溶液电导率的变化,完成了高频电磁场的抑垢效果的客观评价,并取得了良好的预期结果。     

A study of autoxidation reaction fouling in heat exchangers

The mechanism of autoxidation reaction fouling in single phase liquid heat transfer under turbulent flow conditions was studied using model solutions of indene in lube oil recirculated through a tubular fouling probe which permitted both thermal and mass deposition measurements. The fouling rate was initially constant, and then accelerated as polyperoxide gums reached their solubility limit. Deposit composition and morphology in the tubular device are compared with results obtained in an annular probe with a short heated length. The initial fouling data collected over surface temperatures of 180?255°C and flow velocities of 0.5–2.6 m/s (Re = 3000 ? 16000) gave reasonable agreement with a boundary layer reaction model.     

Polymer adsorption on multicomponent surfaces with relevance to membrane fouling

Block copolymer thin films that include low surface energy domains are analyzed as a possible way to overcome the problem of membrane fouling by proteins and other natural organic matter. A model is presented that accounts for both fouling due to chemical interactions between the solute and surface and due to convective deposition. Guidelines for the formation of novel membranes with improved fouling-resistant properties are suggested based on comparison of the relative permeate flux decline due to fouling on different model copolymer membranes. In general, it is observed that copolymer films having small and dispersed polymer blocks that interact unfavorably with the fouling species show an overall decrease in fouling and increase in permeate flux compared with the homopolymer films.     

Performance of two heat transfer fouling probes for various fluids

The predictions of two commonly used fouling monitoring devices, namely a heated rod in an annulus and a coiled wire in cross-flow are compared. As fouling fluids, heptane with dissolved styrene (to simulate chemical reaction fouling), heptane with suspended particles (to simulate particulate fouling) and Kraft pulp black liquor (where both the above fouling mechanisms may occur) have been used.     

水质工况对硫酸钙污垢特性的影响

实验研究了水质工况对硫酸钙污垢特性的影响,在管内流速、入口温度、工质浓度、化学方程式和阴离子浓度5个方面分别研究氯离子和硝酸根离子对硫酸钙结垢特性的影响。结果表明,阴离子对硫酸钙污垢的形成有一定的促进作用,但这种促进作用受实验管段流速的影响,流速越大,促进作用越小,与管段入口温度和工质浓度没有明显关系。电镜观察结果显示,含有大量硝酸根离子的硫酸钙溶液在不锈钢圆管内结垢致密且厚重,工质溶液以条状和块状混晶析出硫酸钙晶体,晶体紧密的聚集。含有大量氯离子的硫酸钙溶液在不锈钢圆管内结垢疏松且均匀,工质溶液以条状析出硫酸钙晶体,晶体间没有明显的聚集现象。     

强制对流传热的换热表面结垢特性实验研究

An experimental study was conducted to investigate the fouling process of calcium carbonate on the heat transfer surface, during forced convective heat transfer. The dynamic monitoring apparatus of fouling resistance was set up for the present experiments. The fouling behavio（s were examined under different factors including fluid velocity, hardness,alkalinity, solution temperature, and wall temperature. Asymptotic fouling curves varying with time were obtained. The fouling rate and asymptotic fouling resistance increased and the induction periods were shortened with the fluid velocity decreasing, hardness andalkalinity increasing, and solution temperature and heat transfer surface temperature increasing. Thecomponents of fouling that formed on the heat transfer surface included crystallization fouling and particulate fouling. The thermal performance parameter of fouling,ρfhf, varied from 380 to 2600 kg·W·（m^4·K）^-1, increasing with growing velocity and decreasing solution temperature, hardness or alkalinity. Furthermore, the thermal conductivity of fouling, λf, varied from 1.7 to 2.2 W·（m·K）^-1 .     

超滤集成工艺对西北村镇窖水处理的应用研究

研究了以超滤为核心,流程为颗粒活性炭-纳米金属簇-超滤-紫外线的集成净水工艺对原水中浊度、CODMn、氨氮的去除,进行了不同原水浊度下超滤的膜污染成因分析和化学清洗试验。结果表明,集成工艺出水浊度稳定在1 NTU以下,对CODMn和氨氮的平均去除率为29.86%和50.95%。出水水质达到了现行GB 5749-2006的要求。在短时间内较高浊度的进水对超滤膜不会造成不可逆的膜污染,但在持续较高浊度进水条件下膜阻力会快速提高并最终造成膜污染。对原水中的有机物和浊度进行更有效的预处理能减缓膜污染的进程,膜污染发生后进行有针对性的化学清洗能有效的恢复膜通量。