制备硅藻土和珍珠岩助滤剂的科学基础

本文在分析过滤机制和基本过滤方程的基础上,认为影响过滤速度的主要因素是助滤剂的比表面、堆比重和颗粒大小分布。并根据硅藻土和珍珠岩的物理化学性质,讨论了制备助滤剂的科学基础。认为低品位硅藻土和珍珠岩经过适当加工是可以制成合格助滤剂的;而由多孔硅藻土和外形不规则的珍珠岩构成的复合助滤剂,有利于形成“刚性桥架”结构的滤饼层.它的过滤性能可以得到改善。     

SCIENTIFIC BASES FOR PREPARATICN OF DIATOMITE AND PERLITE FLTER-AID

According to the filtration mechanism andfiltration formula, it is considered that thesurface area, bulk density and grain size distri-bution of filter-aid are the main factors affectingthe filtration rate. On the basis of analysing phy-sical and chemical properties of diatomite and per-lite, the scientific bases for preparation of filteraid are discussed. It is possible that the complexfilter aid, which is made up of low grade diatomiteand perlite, is favourable to build-up a fine"steely-bridged structure" for the filter cake, andits filtration performance of beer could be improvedas good as that of commercial filter-aid made fromhigh grade diatomite. The above points have beendemonstrated by the results of laboratorial andindustrial experiments of beer filtration.     

均质石英砂滤料过滤性能的试验研究

均质石英砂滤料是当前国内水厂过滤技术应用的主要填料之一。均质石英砂滤料过滤能较好地克服滤层表面堵塞，充分发挥整个滤床的截污作用，提高过滤效率。本文通过模型试验成果，讨论了均质石英砂滤料的过滤性能和应用效果     

石英砂均质滤料过滤性能的试验研究

石英砂均质滤料是国内水厂过滤技术应用的主要填料之一。石英砂均质过料滤能较好地克服滤料层表面堵塞,更好地发挥整个滤床的截污能力,提高过滤效率。通过模型试验成果,对石英砂均质滤料的过滤性能和应用效果进行了讨论。     

Filtration of fine particles in atmospheric aerosol with electrospinning nanofibers and its size distribution

In this study,the size distribution of atmospheric aerosol in Beijing was monitored by the scanning mobility particle sizer spectrometer and the optical particle sizer.The size of particles in atmospheric aerosol was primarily distributed in the range of less than 1 m.It showed different changes with the mass concentrations of particulate matters with an aerodynamic diameter of 2.5 m(PM2.5)for different sizes of fine particles.The amount of ultrafine particles(less than about 60 nm)decreased while the larger ones(60 nm)increased along with the mass concentration of PM2.5 in atmospheric aerosol.This was because of the formation of the secondary atmospheric aerosol.The polylactic acid(PLA)nanofibers were prepared for filtering the aerosol by electrospinning.PLA nanofiber mats were used as the middle layer to design the composite filter membranes.Atmospheric aerosol was used as dust source in the filtration test.The results showed that the filtration efficiency of the composite filter media increased along with the thickness of nanofiber mats,which was controlled by the collection time during electrospinning.Filtration efficiency can be improved obviously by compositing with a thin layer of nanofibers.     

来沙条件变化对河床形态及推移质运动的影响

摘要：针对山区河流的来沙条件的不确定性导致的河流形态变化的问题,根据J . G. Venditti的系列来沙条件变化水槽试验成果,引入无量纲参数河床结构强度Sp,充分考虑推移质泥沙运动特性,探讨了来沙条件变化对卵石河床形态、推移质输沙率和河床级配的影响。结果表明:在已经粗化的河床上加入细沙会对河床形态、推移质输沙率和河床级配产生影响。加入细沙会造成河床重新出现冲淤变化,底坡变大,冲刷变严重,最终降低河床结构强度Sp;加沙会增大推移质输沙率,其中中值粒径为3mm的细沙运动表现为行进推移质,而中值粒径为8mm的粗沙运动表现为结构推移质;加入细沙后会细化河床,且加入的粒径越小,细化效果越明显,加入中值粒径为3mm的细沙后推移质的中值粒径先减小后增大,与加入中值粒径为8mm的粗沙后推移质的中值粒径先增大后减小相反。     

高温下粉尘在多孔介质中的分布试验研究

使用结构与颗粒层类似的多孔介质模拟颗粒层对高炉粉尘进行除尘,研究一定温度和粉尘浓度条件下,粉尘在多孔介质中横向和纵向2个方向上的分布.验证了过滤式除尘中粉尘初层的形成对除尘效果的重要作用,发现随着温度升高和粉尘浓度的增加,由于粉尘惯性碰撞和拦截效应增大,导致粉尘在多孔介质中纵向和横向的分布呈增加趋势,粉尘的横向弥散半径最大值出现在第三或第四片多孔介质中,且最大值约为气流入口内径的3倍.     

袋式收尘器在粉磨系统中的应用研究

本文按粉磨系统的工况参数对袋式收尘器进行了试验，分析了过滤风速、入口含尘浓度、喷吹压力及脉冲宽度对粉尘负荷压降的影响程度，确定了结构压力损失、再生滤袋压力损失与过滤风速的关系式及粉尘负荷压力损失与过滤风速、入口粉尘浓度的关系式，提出了合理的喷吹制度的参数范围，讨论了应用过程中遇到的问题。     

滤池工作参数对连续式砂滤器处理效果的影响

内循环连续式过滤器是一种新型的一体化水处理设备。利用微絮凝过滤技术,采用体内循环洗砂系统,连续过滤,连续反冲洗。对影响内循环连续式过滤器工作效率的滤池工作参数进行研究,提出设备运行的关键工作参数;滤料粒径0．70－1．00mm、滤层厚度0．6m,滤速＜12m/h,提砂管内气水比9－11,砂循环速率2－4mm/min。     

Comparative filtration and dewatering behavior of vitrinite and inertinite of bituminous coal: Experiment and simulation study

The filtration and dewatering of fine clean coal not only ensure industrial water recycle in coal washing plant, but also reduce the moisture of coal product in order to meet the requirements of combustion or coking industry. Fine clean coal is mainly composed by organic matter, and the property difference of different organic matter determines the filtration and dewatering behavior. In this investigation, vitrinite and inertinite were separated from a clean bituminous coal, and the comparative filtration and dewatering behavior of vitrinite and inertinite were conducted. The results showed that inertinite has lower dewatering rate and higher filter cake moisture than vitrinite. The analysis of filter cake structure showed that inertinite particle is easier to be broken into small particles due to the difference of mechanical properties, thus forming more compact filter cake than vitrinite. The analysis of particle surface properties showed that vitrinite is more hydrophobic than inertinite, which makes water easier drained from filter cake. The simulation study showed that the structure of inertinite is more porous than that of vitrinite,and the interaction between inertinite and water is stronger than that between vitrinite and water. This study provides a theoretical basis for improving coal dewatering by selectively improving coal maceral hydrophobicity.     

Effect of a starch-based filter aid on the dewatering of fine clean coal

The dewatering of fine, flotation cleaned coals from Huaibei and Xuzhou (bituminous) and Yongcheng (anthracite) were studied. The supernatant and filter cake were examined to determine the rate and extent of flocculation and dewatering. A starch-based filter aid was used to increase flocculation and dewatering rates. The filtration constant, K, and compression index, s, of the Yongcheng slurry were measured under various conditions. A designed experiment was performed to determine optimum conditions for dewatering. The results showed that the filter aid enhanced flocculation and coagulation of the fine cleaned coal slurry, enhanced the structure of the filter cake and promoted dewatering of the cake. Moisture content in the cake was reduced to 17% after vacuum filtration.     

小型袋式除尘器研究

为解决散粮装卸输送过程产生的粉尘污染问题，选择小型袋式除尘器为除尘设备进行研究。使用不同滤料对袋式除尘器阻力性能进行实验得出结论，其滤料的选取是关键的一步，在高比负荷、高过滤风速下运行时其壳体阻力仍较一般袋式除尘器小。单相流时采用体积较小的W型滤袋，以工业涤纶208或针刺毡做滤料，袋式除尘器的总阻力较小，且主要来源于壳体阻力。     

柴油机颗粒捕集器内颗粒层不均匀分布的数值研究

针对壁流式柴油机颗粒捕集器捕集颗粒物的工作过程,建立了描述通道内流场和颗粒层分布的一维非稳态模型.通过数值计算,研究了壁面渗透系数不均匀对颗粒层分布和过滤压强的影响.研究结果表明:壁面渗透系数不均匀造成颗粒沉积高度的不均匀,渗透系数大的位置颗粒层沉积高度大.在相同的不均匀偏差条件下,平均壁面渗透系数越低,颗粒层高度的不...     

珍珠岩助滤剂的制备研究

本文讨论了制造助滤剂的科学基础,测定了珍珠岩助滤剂的化学性质和物理结构.研究了助滤剂制造工艺和过滤工艺对啤酒过滤性能的影响,发现容重和粒度分布是珍珠岩助滤剂制造工艺的关键参数.过滤动力学试验及工业啤酒过滤试验表明,开发成功的珍珠岩助滤剂是良好的啤酒助滤剂.     

高效菌培养投加系统中原废水过滤除菌的研究

过滤除菌系统由绝对过滤器和过滤柱构成。绝对过滤器采用微孔滤膜 ;过滤柱中的滤料选用石英砂和陶粒组成的双层滤料。该系统既能有效去除原废水中的杂菌 ,又能最大限度地保留原废水中的细菌营养物质     

均粒石英砂滤料过滤效果的生产性试验与应用

目的将快滤池的传统滤层改造为均粒石英砂滤层,为的是改善滤池的工作性能,提高产水量.方法采用均粒石英砂滤料,粗粒石英砂滤料及常规石英砂滤料进行生产对比试验,研究粒径与过滤周期、滤速、反冲洗强度、反冲洗时间的关系.结果研究表明,均粒滤料与非均粒滤料相比,滤速提高15%以上,过滤周期提高13h以上,反冲洗强度和反冲洗时间变化不大.结论均粒滤料的过滤性能优于非均粒滤料,将常规石英砂滤料更换为平均粒径相同的均粒石英砂滤料,能够延长过滤周期,提高产水量,经济效益明显.     

颗粒物在多孔介质内部沉积以及脱附的研究进展

颗粒捕集器可有效降低颗粒物排放, 其过滤性能和再生时的颗粒排放都与颗粒物在多孔介质表面的沉积和脱附特性密切相关。本文综述国内外近年来颗粒物在单根、双根骨架以及单层和双层过滤片上的沉积以及脱附规律的研究进展, 包括宏观物理特征和微观结构特征, 总结灰沉积特性与颗粒物沉积以及脱附特性的相互影响规律, 提出对柴油机颗粒物在多孔介质表面的沉积以及脱附过程的研究是未来重要的研究方向。这方面的成果可以对过滤介质的结构参数和运行参数进行优化, 同时对过滤性能的预测有重要意义。     

新型纤维滤料过滤特性研究

开发了一种新型的纤维滤料型式———短纤维束滤料 ,对该种滤料的过滤特性进行了试验研究。试验发现 ,短纤维束滤料滤层的孔隙率沿过滤方向由大到小 ,为变孔隙滤层。通过与砂滤进行对比试验 ,结果表明 ,短纤维束过滤器具有滤速高、截污量大、出水水质好、容易反洗等特点 ,具有很高的过滤效能。以此开发的高效纤维过滤器已得到应用     

压滤泥饼调制泥浆及其在砂层渣土改良中的应用研究

为解决泥水平衡盾构施工中压滤泥饼废弃产生的环保问题,提出一种利用压滤泥饼调制泥浆改良砂层渣土的新方法。从泥浆的密度控制、稳定性控制和粘度控制三个方面,开展压滤泥饼调制泥浆试验,从流动性与渗透性角度,确定改良砂层渣土的适宜泥浆掺量。结果表明：压滤泥饼调制的泥浆密度宜在1.29~1.34 g/cm³之间,掺入泥浆质量3%~5%的钠基膨润土,泥浆具有较高的稳定性和粘度。掺入渣土质量6%~10%的调制泥浆,便能达到与使用纯膨润土改良渣土相近的效果,泥浆用量大为减少。所以利用压滤泥饼调制泥浆并运用于砂层渣土改良是可行的,是一个节能环保的新思路。     

过滤工艺中颤蚓的迁移分布规律

中试条件下研究了颤蚓在过滤工艺中的迁移分布规律,并考察了滤速和过滤周期对颤蚓迁移分布的影响,以及反冲洗后滤池中颤蚓的分布情况。结果表明：颤蚓在滤池中沿滤床深度方向的迁移与颤蚓体长和滤料粒径有关,颤蚓体长越小、滤料粒径越大,则迁移幅度越大;滤速是颤蚓迁移的主要动力,滤速的提高会引起下层滤床中颤蚓数量的增加,颤蚓泄露风险加大;过滤周期的延长将促进颤蚓的迁移,适当缩短过滤周期有利于水厂颤蚓泄露风险控制;反冲洗可以实现颤蚓从净水工艺中的彻底去除,反冲洗强度越大,颤蚓的去除效果越好。为有效控制颤蚓泄露风险,滤池滤速和过滤周期宜分别控制在9．4m／h和12h以下,反冲洗强度则控制在25L／s·m^2左右,此时颤蚓去除率为97．7％。