我国冷冻机组水冷器污垢经济损失研究

通过有无自动清洗技术的对比试验和实际测试，结合献统计数据，对冷冻机组水冷器污垢引起的效率损失作出评估。在此基础上根据《中国机械工业年鉴》数据，从宏观上逐项分析评估水垢造成我国冷冻机组水冷器的设备费，运行水费和运行电费三方面的损失，总计达到每年20亿元以上。因此，在水冷器中大力推广自动清洗技术具有十分重要的经济意义。     

冷冻机立式水冷器污垢的塑料螺旋齿管自动清洗技术研究

冷冻机组立式水冷器的水垢损失每年高达十多亿元。依据其特低流速的特点，研究成功具有在线、连续自动清洗功能的塑料螺旋齿管技术。其原理是由冷凝管与螺旋齿管形成螺旋流道，使冷却水作快速螺旋线流动，其反作用给螺旋齿管形成较强的自转力矩。通过理论分析和多种结构参数的试验研究表明：污垢清洗能力强；自转力矩与冷却水流量二次方正比，较大的内管直径、较小的螺旋角有利于力矩强化，其中力矩最优化的螺旋齿管的力矩强化能达到塑料扭带的241％，可以在0．4m／s以上的流速下可靠应用；传热系数平均提高50％；制造简单。虽然螺旋齿管的阻力大，但是立式水冷器的落差很大。位能充裕，因此，具有很好的工程应用价值．     

轴承旋流强化的管内污垢自动清洗扭带技术

冷饮与速冻工业的水冷器大多为列管式结构。实际运行的管内冷却水流速一般为0．5～1．0m／s，易结垢，效率低。通过强化理论分析和结构设计的优化试验，研究成功了旋流轴承强化塑料扭带自动清洗技术，能够使现有光滑扭带的清洗力矩成倍增加；可以使水冷管长度为2m、4m、6m的水冷器对管内冷却水的流速要求由原先的1m／s以上，分别下降至0．4m／s、0．5m／s、0．6m／s，从而使多数水冷器可以直接应用管内污垢自转塑料扭带自动清洗技术，并且流体的阻力不大，结构简单，便于推广应用。     

水冷器管内污垢自动清洗扭带及旋流轴承强化

冷饮与速冻工业的水冷器大多为列管式传热设备。实际运行的管内冷却水流速一般在0．5—1．0m／s范围，容易结水垢，效率低下。本文研究的旋流轴承强化的塑料扭带技术，可以在1．0m／s以下流速的管内实行自动清洗防垢，又冷却强化，并且流体阻力不大，结构简单，推广应用价值较高。     

水冷器管污垢自动清洗扭带及其旋流轴承强化

工业中使用的水冷器大多为列管式传热设备。实际运行的管内冷却水流速一般在0．5～0．8m／s范围，容易结水垢．效率低下。本文研究的旋流轴承强化的塑料扭带技术．可以在1．0m／s以下较低流速的管内实行自动清洗防垢，又强化冷却，并且流体阻力不大，结构简单，推广应用价值较高。     

国内外消息

用冷冻设备制取高温水、蒸气的方法 大家知道,食品加工厂都有冷冻设备和锅炉,但从来锅炉和冷冻机之间没有热量联系,冷冻机的废热从来就用冷却塔散发在空气和水中。如果把这些热量回收,输送到锅炉里.不仅能够大幅度地节约能源,而且锅炉的加热时间也将缩短,使用的台数也可以减少。     

盐矿电厂真空冷凝器的纽带自动清洗技术研究

本文简要介绍了污垢对电厂冷凝器真空度和出力的严重影响，叙述了自转塑料纽带的污垢自动清洗原理，模拟试验证明自转纽带的清洗除垢能力强，足以满足传热设备的清洗防垢要求。以电厂汽轮机的凝汽器污垢清洗为例，定量分析了不同厚度污垢对传热系数的影响幅度，举例计算采用自转塑料纽带清洗技术可以创造的高效益。     

炭黑急冷器中异形波纹管的承载能力与补偿性能研究

炭黑急冷器中,烟气温度与冷却水温度相差非常大,导致设备中存在很大的热膨胀差。若设备中的热膨胀差过大且未得到良好的热补偿,则设备有可能无法正常运行甚至遭到破坏。针对这种现象,在炭黑急冷器中设置异形(Ω形)波纹管。文中以Ω形波纹管为研究对象,取波纹管中独立的关键参数,运用ANSYS软件对不同结构参数进行数值模拟分析,得到了波纹管结构参数对承载能力和补偿性能的影响规律,并为合理选择波纹管结构参数提供了指导。     

处理无机盐污垢的方法

制浆造纸工厂设备产生无机盐污垢会增加操作费用，延长停机时间和增加设备维修次数。美国农林部林产品实验室科技人员提供了几种消除这种无机盐污垢的方法。在蒸煮器、二氧化氯漂白段、碱抽提段和绿液、白液粗滤器都会形成无机盐污垢，包括石灰垢，碳酸钙、草酸钙和硫酸钡结的污垢，在所有这些情况下，明确无机盐污垢形成的基本原理，将有助于消除或减少结垢，通过控制操作条件例如pH值，可消除碳酸钙结垢。[第一段]     

微生物污垢的生长模型与受力分析

换热设备表面形成的微生物污垢严重影响了换热效率和系统安全。为了减少微生物污垢,需要研究微生物污垢的生长机理和受力特性。该文采用3维细胞自动机模型,对微生物污垢进行了生长模拟,并模拟了混合菌种的相互抑制。针对微生物污垢形状多样的特点,提出了形状因子的概念,分析了形状因子与受力的关系。该文细胞自动机模型采用了换热设备的代表性菌种——枯草芽孢杆菌和鳗鱼气单胞菌。采用该模型模拟两种菌种的生长机理和相互抑制,结果发现换热设备抑垢应侧重于枯草芽孢杆菌。该文提出的形状因子能较好量化污垢形状,有效地描述了3种典型污垢形状。形状因子简化了污垢形状与受力的关联分析,有助于不同形状污垢的对比。     

FOULING MODELS FOR HEAT EXCHANGERS IN DAIRY PROCESSING: A REVIEW

Fouling is a common food industry‐wide issue during thermal treatment using heat exchangers. It directly contributes toward increased energy costs in operation and maintenance, production losses and energy and water losses because of the repetitive cleaning operation, i.e., every 5–10 h in fluid food industry. There has been a considerable amount of work on modeling of the fouling process as well as the hydrodynamic and thermodynamic performances of heat exchangers. A variety of different fouling kinetics exists depending upon food components, types of heat exchangers and operating conditions. The available information on existing fouling models is summarized in terms of fouling mechanisms, dynamic performances of heat exchangers and integrated fouling dynamics. This review provides the basis for developing a vision of further research for understanding, quantifying and minimizing fouling of food materials in heat exchangers.     

A critical review on surface modifications mitigating dairy fouling

Thermal treatments performed in food processing industries generate fouling. This fouling deposit impairs heat transfer mechanism by creating a thermal resistance, thus leading to regular shutdown of the processes. Therefore, periodic and harsh cleaning-in-place (CIP) procedures are implemented. This CIP involves the use of chemicals and high amounts of water, thus increasing environmental burden. It has been estimated that 80% of production costs are owed to dairy fouling deposit. Since the 1970s, different types of surface modifications have been performed either to prevent fouling deposition (anti-fouling) or to facilitate removal (fouling-release). This review points out the impacts of surface modification on type A dairy fouling and on cleaning behaviors under batch and continuous flow conditions. Both types of anti-fouling and fouling-release coatings are reported as well as the different techniques used to modify stainless steel surface. Finally, methods for testing and characterising the effectiveness of coatings in mitigating dairy fouling are discussed.     

凝汽器阻垢除垢的意义及方法探讨

在热力发电厂中凝汽器结垢是一种普遍现象,当垢结积到一定程度后,使凝汽器换热情况减弱,造成汽轮机经济运行受损,增加运行成本,因此,在许多电厂都采用了不同的方法进行阻垢除垢,同时也花费了不少的财力物力。本文对目前一些热力发电厂采用的阻垢除垢的方法进行比较探讨。     

Unified membrane fouling index for low pressure membrane filtration of natural waters: principles and methodology

Membrane filtration is considered an important technology that can contribute to the sustainability of water supplies. However, its continued development necessitates the establishment of proper techniques for the assessment of membrane fouling. Unified Membrane Fouling Index (UMFI) was developed in this study in order to quantify and assess the fouling of low-pressure membranes (LPM) observed at various scales of water treatment. The foundation of UMFI is a revised Hermia model applied to both constant pressure and constant flux filtration. The adoption of UMFI makes it possible to simplify and standardize the bench-scale testing of membrane fouling potential by directly using the commercial LPM of interest. This approach can overcome a major challenge to fouling assessment, i.e., the membrane-specificity of fouling potential, which has not been wholly addressed by existing fouling indices. The fundamentals of UMFI are presented in this paper, together with the methodology for bench-scale testing. The application of UMFI to the assessment of the fouling of a LPM by a natural surface water is also discussed. Good agreement between bench-scale UMFI and pilot-scale UMFI was found, suggesting the validity of this new scientific concept for environmental applications.     

菜籽蛋白超滤液反冲对超滤膜污染的控制研究

超滤是制备植物油料蛋白的先进工艺技术，但膜的污染问题严重影响超滤技术的推广应用。本文在研究了菜籽蛋白水溶液在中空纤维超滤装置中的超滤行为之后，研究了膜面透过液反冲对膜污染的控制作用。实验结果表明：菜籽蛋白水溶液的超滤浓缩速率随时间延长而下降；对工作中的超滤膜进行定期间歇反冲（反冲时间20s、反冲频率为1次／15min、反冲压差为0．2MPa），是控制膜污染程度的有效措施，这样可以使超滤膜的透水速率恢复90％以上。     

Effect of coagulation on the size of MF and UF membrane foulants

Microfiltration (MF) and ultrafiltration (UF) have become common water treatment technologies for the removal of particles from natural waters. Many water utilities are now integrating MF/UF with other treatment processes to provide treatment for nonparticulate contaminants. Research is needed to understand the impact that other processes have on MF/UF performance. This study was conducted to investigate the interactions between water quality, coagulation, and membrane fouling. The study examined the fouling of MF/UF membranes by natural waters with and without coagulation by specific fractions of constituents in natural water, separated by size. This research found thatthe component of natural organic matter (NOM) smaller than 100 kDa contributes relatively little to fouling during filtration of either raw or coagulated water. The fraction between 1 microm and 100 kDa contributes a significant portion of the fouling. After coagulation pretreatment, fouling due to various size fractions in the feedwater can change.     

Environmental costs of freshwater eutrophication in England and Wales

Eutrophication has many known consequences, but there are few data on the environmental and health costs. We developed a new framework of cost categories that assess both social and ecological damage costs and policy response costs. These findings indicate the severe effects of nutrient enrichment and eutrophication on many sectors of the economy. We estimate the damage costs of freshwater eutrophication in England and Wales to be $105-160 million yr(-1) (pound 75.0-114.3 m). The policy response costs are a measure of how much is being spent to address this damage, and these amount to $77 million yr(-1) pound 54.8 m). The damage costs are dominated by seven items each with costs of $15 million yr(-1) or more: reduced value of waterfront dwellings, drinking water treatment costs for nitrogen removal, reduced recreational and amenity value of water bodies, drinking water treatment costs for removal of algal toxins and decomposition products, reduced value of nonpolluted atmosphere, negative ecological effects on biota, and net economic losses from the tourist industry. In common with other environmental problems, it would represent net value (or cost reduction) if damage was prevented at source. A variety of effective economic, regulatory, and administrative policy instruments are available for internalizing these costs.     

Ultrafiltration fouling of amylose solution: Behavior, characterization and mechanism

Applications of ultrafiltration membrane often deal with feed streams containing amylose starch. This paper describes a detailed investigation of amylose fouling during ultrafiltration. Commercial membranes made of polysulfone and fluoro polymer were used. Both adsorptive and ultrafiltration fouling were investigated. Experiments using different membrane characteristics, feed concentrations and trans-membrane pressures were carried out. The resulting fouling was characterized by water flux and contact angle measurements and was visualized by scanning electron microscopy (SEM). The results suggest that solute adsorption has occurred as noticed by significant water flux reductions as well as changes in membrane characteristics. Further, both reversible and irreversible fouling have occurred during ultrafiltration with irreversible fouling was more dominant. Apparently, cake layer formation initiated by either adsorption due to hydrophobic–hydrophobic interactions or pore blocking is the dominant fouling mechanism. However, pore narrowing instead of pore blocking was also observed for the membrane having large and relative uniform pore structure or for the ultrafiltration using low trans-membrane pressure or low solute concentration. Membrane autopsy using SEM confirmed the formation of solute layer on the membrane surface.     

菜籽蛋白水溶液的超滤行为及在线控制膜污染的研究

研究了菜籽蛋白水溶液在中空纤维超滤膜膜管中的超滤行为，探讨了菜籽蛋白对超滤膜的污染机理，设计安装了反冲装置，摸索出了可在线控制膜污染的最佳反冲工艺参数。实验结果表明：菜籽蛋白水溶液的超滤浓缩速率随时间延长而下降，当超滤时间接近15min时，膜面上会形成凝胶层“二次膜”；对工作中的超滤膜每隔15min就用0．2MPa的压差反冲20s，可使透水速率恢复94％以上。