以PTFE为基布的混织滤料过滤性能及其在燃煤电厂的应用

滤料是袋式除尘器和电袋复合除尘器的核心,通过对目前常用的两种PTFE混织滤料材质结构、加工工艺及适用条件进行的对比分析,并列举了其在燃煤电厂中的应用效果,阐明了混织滤料的优良过滤性能,适用于烟气温度高、粉尘排放要求较高、工况变化大的燃煤电厂。     

袋式除尘器滤料过滤性能研究

滤料是袋式除尘器的重要部件,滤料的过滤性能对除尘器的运行阻力及烟尘排放浓度有着直接影响。聚苯硫醚（PPS）、聚四氟乙烯（PTFE）和聚亚酰胺（P84）是袋式除尘器常用的几种滤料,对其进行了常温过滤性能测试。测试结果表明,即使采用相同的纤维,不同滤料厂家的产品性能也存在较大的差异。     

覆膜滤料与常规滤料的性能测试及比较

随着污染物排放标准的日趋严格，覆膜滤料以其优良的过滤性能引起了人们的关注。针对覆膜滤料的过滤机理、过滤效率、过滤阻力、过滤风速等性能指标的研究现状进行了分析，并与常规针刺毡滤料进行了比较，指出了覆膜滤料的一些主要性能优势，以供实际选用时参考。     

曝气生物滤池中滤料的应用研究进展

介绍了曝气生物滤池的工作原理和生物滤料的性能;重点综述了无机滤料的分类、滤料的改性和复合陶粒生物滤料的应用情况,并对双层滤料工艺进行了讨论;指出今后应加强生物膜在滤料上的生存特征及适应性的研究,以便寻求能改善滤料性能的新工艺和方法。     

国外动态

在1980年,“化学处理”Vaaler奖比赛中,Huyck公司生产的袋滤器用玻璃纤维针毡滤料,赢得了荣誉奖。这种滤料的特点是过滤负荷大,强度高,并可在260℃下进行过滤操作。玻璃纤维针毡滤料,实质上是一种把直径3.8微米的Beta玻璃纤维,针刺到全玻璃纤维底布上的网状过滤介质。为了提高这种滤料的挠性和耐酸性,采用特别的树脂进行处理。     

改性核桃壳滤料对油田含油污水的过滤效果

采用亚硫酸氢镁蒸煮法对核桃壳滤料进行亲水改性,考察了改性核桃壳滤料对油田含油污水的过滤、反洗效果,探讨了改性前后核桃壳滤料的过滤过程及乳化油捕集机理。实验结果表明:在蒸煮温度为95℃、蒸煮时间为5 h、w(MgHSO_3)为5%的条件下,核桃壳滤料接触角由改性前的117.1°降至62.4°;分4批次过滤含油污水,改性核桃壳滤料的平均出水含油量为32.3 mg/L,平均油去除率为78.5%,平均浊度为7.7 NTU,平均浊度去除率为89.7%;改性核桃壳滤料的反洗效果显著改善,反洗水含油量由520 mg/L提高到840 mg/L,核桃壳滤料增重率由4.3%下降到0.2%。     

国外动态

袋滤器用针毡滤料Envir.Scien.&Tech.,13[12],1472—5(1979).针毡滤料是三维空间的过滤介质,纤维杂乱无章地排列,其空隙度均匀。针毡滤料可高效地捕集亚微级粉尘粒     

燃煤电厂对过滤材料的要求及其解决方案

随着燃煤电厂烟尘排放标准的日益严格,发展袋式除尘器改成为必然趋势。通过对我国燃煤电厂烟气成分和工况条件的分析,提出了采用新型PPS复合滤料及改进的玻璃纤维覆膜滤料的方案可以满足燃煤电厂袋式除尘器所需滤料的要求。     

TiO2-PTFE光催化膜的制备及性能

以聚四氟乙烯（PTFE）乳液和纳米TiO2粉末为原料,采用无水乙醇为溶剂,经辊压后与不锈钢网结合,制备了多孔固定化TiO2-PTFE光催化膜。膜性能研究结果表明,m（TiO2）：m（PTFE）=4时,光催化反应处理质量浓度为20mg／L的苯甲酸溶液,2h内TOC去除率高达81．3％。通过扫描电子显微镜观察,TiO2-PTFE光催化膜表面平整,且孔隙分布均匀。TiO2最佳负载量为15mg／cm2。在优化反应条件下同悬浮态TiO2光催化反应体系相比,TiO2-PTFE光催化膜对光源有更高的利用率,表现出更佳的催化活性。     

热喷涂防腐涂层在生物质锅炉中的研究进展

简要介绍了常用热喷涂技术,基于对热喷涂防腐涂层在燃煤锅炉防腐工作中的研究进展,进一步分析了热喷涂涂层在生物质锅炉防腐中的现状,介绍了金属涂层中的NiCrTiFe系列涂层、陶瓷涂层及金属陶瓷复合涂层、纳米涂层等现有技术比较成熟的涂层,对热喷涂防腐涂层的发展趋势进行了展望。     

Preliminary Study of Non-woven Composite: Effect of Needle Punching and Kenaf Fiber Loadings on Non-woven Thermoplastic Composites Prepared From Kenaf and Polypropylene Fiber

Non-woven composites were produced using kenaf (bast) fiber and polypropylene (PP) fiber. The effects of needle punching process, number of needle and kenaf fiber loadings on the properties of non-woven composite were studied. The aspect ratio of kenaf fiber was also measured in this study. The aspect ratio of most of kenaf fiber used was in the range of 200–400. The results indicated that the mechanical strength of the non-woven composite was significantly influenced by the percentage of kenaf fiber. This may due to the evenly mixed kenaf and PP fibers during carding process prior to the mechanical interlocking by needle punching process. The tensile strength, modulus and toughness were enhanced with the incorporation of carded and needle punched fibers. The number of needle used in needle punching process had a significant effect on the strength of the composite. This was evident in SEM micrograph where composite prepared from carded to needle punched non-woven web showed better wettability as compared to composite prepared from carded non-woven web only. However, no significant difference was observed in water absorption and thickness swelling tests for composites prepared with different number of needles.     

Release Characteristics of Nutrients from Polymer-coated Compound Controlled Release Fertilizers

Reliable information regarding release characteristics of nutrients from a polymer-coated controlled release fertilizer (CRF) is essential for beneficial agronomic and environmental results. Significant knowledge regarding nitrogen release from polymer-coated urea was gained while the information regarding the release of the different nutrients contained in polymer-coated compound N–P–K CRF remains limited. An experiment in which major factors affecting the differential release of nutrients from two coated compound CRF was performed in free water, water saturated sand and sand at field capacity. In general, nitrate release was the fastest, followed by ammonium and potassium whereas phosphate was significantly slower, with a rate of linear release in free water 45–70% slower than that of nitrate. Little differences were obtained for the lag periods of nitrate, ammonium and potassium release (2–10 days) under the experimental conditions, whereas for P they were one order of magnitude larger. The main factor slowing the release was assumed to be the lower solubility of ions with P being the least soluble. Release into free water was, expectedly, somewhat faster than that into saturated sand and significantly faster as compared to sand at field capacity and particularly so for P. Raising the temperature from 20 °C to 40 °C increased the rate of linear release of the different nutrients. The energy of activation, EA_rel, estimated for the linear release, of the different nutrients, was narrow ranging between 37 to 46 (KJ mol⁻¹) whereas the mean values obtained for the two CRF, differing by 50% in coating thickness, was non-significant. However, EA_rel was significantly different in different media. The complex effect of temperature on the lag period and nutrient interactions during release deserve further investigation.     

Synthesis of a block copolymer of poly(3-hydroxybutyrate) and poly(ethylene glycol) and its application to biodegradable polymer blends

A block copolymer {P[(R,S)-HB-b-EG]} of atactic poly[(R,S)-3-hydroxybutyrate] {P[(R,S)-HB]} and poly(ethylene glycol) (PEG) was prepared by the ring-opening polymerization of -butyrolactone in the presence of a macroinitiator (PEG/ZnEt₂/H₂O) which had been produced by the reaction of ,-dihydroxy PEG ( _n=3000) with ZnEt₂/H₂O (1/0.6) catalyst. The block copolymer ( _n=10,500, _w/ _n=1.2) was an A-B-A triblock copolymer comprising atactic P[(R,S)-HB] (A) and PEG (B) segments. The miscibility, physical properties, and biodegradability of binary blends of microbial poly[(R)-3-hydroxybutyrate] {P[(R)-HB]} with the block copolymer P[(R,S)-HB-b-EG] has been studied. The glass-transition temperature (T _g) data showed that the P[(R)-HB]/P[(R,S)-HB-b-EG] blend was miscible in the amorphous state. The P[(R)-HB] film became flexible and tough by means of blending with P[(R,S)-HB-b-EG] block copolymer. The enzymatic degradation of blend films was carried out at 37°C and pH 7.4 in a 0.1M phosphate solution of an extracellular PHB depolymerase fromAlcaligenes faecalis. The enzymatic degradation took place solely on the surface of the blend films.     

清洗液和阻垢剂对疏水膜接触角的影响

研究了采用不同pH的酸、碱清洗液及阻垢剂溶液静态浸泡对聚偏氟乙烯(PVDF)和聚四氟乙烯(PTFE)疏水平板膜接触角的影响.实验结果表明:随pH 2.5盐酸和pH2.0草酸浸泡PVDF膜和PTFE膜时间的延长,两种疏水膜的接触角均小幅度减小,说明酸性清洗液对两种疏水膜性能的影响较小;随pH11.5NaOH溶液浸泡膜时间...     

Fe3O4-PTFE电极制备条件和双阴极电-Fenton反应条件的优化

制备了Fe₃O₄-聚四氟乙烯（PTFE）电极,优化了原料配比和焙烧温度。对比了Fe₃O₄-PTFE单阴极和Fe₃O₄-PTFE与乙炔碳黑-PTFE电极并联双阴极体系对模拟Rhb染料废水的处理效果。实验结果表明：在m（Fe₃O₄）∶m（PTFE）=3.0∶2.5、焙烧温度为300 ℃的条件下制备Fe₃O₄-PTFE电极,采用阴极电-Fenton法降解模拟Rhb废水的效果最佳,电解反应120 min时Rhb降解率达86.91%;Fe₃O₄-PTFE电极与乙炔碳黑-PTFE电极并联作为双阴极电解Rhb废水时,最佳电压为6 V,最佳初始废水pH为3,在此条件下电解反应120 min时Rhb降解率达91.65%。     

石化综合污水生化处理中有机污染物的分析

运用GC-MS、紫外光谱及三维荧光光谱扫描技术考察了石化污水处理厂“水解酸化—厌氧处理—好氧处理”工艺的各单元出水中有机污染物的变化情况。总进水中检出84种主要有机污染物,主要含有烃类27种,酚类5种,醛、酯、醇和酮类化合物共24种,胺类4种,腈、有机酸及其他杂环化合物14种,另有10种物质未定性;该工艺的COD累积去除率达87.66%, 64种有机污染物被完全去除,17种有机污染物去除率可达90%以上,接触氧化池出水中主要含杂环化合物和少量醛、醇、酯类化合物。     

The use of the removable thin film coating technique as an alternative to traditional decontamination methods to mitigate and abate hazardous particulates

This article summarizes a study that evaluated a new decontamination technique for the mitigation and abatement of hazardous dust and particulates. Traditional decontamination methods are time‐consuming, expensive, can create airborne hazards, and do not always bring the concentration of the contaminant to acceptable levels. The use of the removable thin film coating will increase efficiency, will not generate airborne hazards, will decrease costs, and, with one application, will bring the hazardous dust concentrations to acceptable levels. Qualitative tests demonstrated that the removable thin film coating reduced the amount of visible luminescent dust (a surrogate for hazardous dust) from various surfaces. It also indicated that wherever there were minute scratches, the coating did not remove all of the dust. However, the qualitative tests showed that this decontamination method worked well as a preventative method, protecting clean areas from becoming contaminated when exposed to the luminescent dust. Further investigation was conducted using a scanning electron microscope (SEM) and carbon dust. Overall, the SEM experiment demonstrated that there was a statistically significant (p = 0.00007) removal of carbon dust (less than 10 μm in size) from surfaces with crevasses larger than 3 μm. The SEM also revealed that there were some limitations where there were large clusters of carbon dust; in these instances, the coating would tear and remain on the sample surface. One method to resolve this limitation involved adding Kevlar^TM fibers to the removable thin film coating. It was thought that this would increase the strength of the coating and eliminate the coating from tearing when removing large clusters of a contaminant. Unfortunately, this did not alleviate the issue. The use of an engineered textile, saturated with the coating, appeared to eliminate the problem with the coating not being able to remove the contaminant from the minute surface scratches and improved the removal process of the coating. © 2008 Wiley Periodicals, Inc.     

石墨毡电极预处理模拟邻甲酚废水

采用聚丙烯腈基石墨毡电极,以NaCl为电解质,在恒流电解的条件下,对质量浓度为1 000 mg/L、COD=3 672 mg/L的模拟邻甲酚废水进行预处理。研究了电解时间、初始废水pH、NaCl加入量、电流密度对邻甲酚去除率的影响,考察了废水的COD变化,并探讨了反应机理。实验结果表明：石墨毡电极具有较好的导电性、吸附性,对邻甲酚具有较好的电化学氧化性能;常温常压下,初始废水pH为6~7、电流密度为90 A/m2、向300 mL废水中加入0.5 g NaCl时,经4 h电解,邻甲酚的去除率达到97.1%,COD的去除率达到47.3%;处理后废水的BOD5/COD由0.04提高至0.33,可不经稀释直接进行生物处理。