燃煤电厂细颗粒物控制技术集成应用及“近零排放”特性

细颗粒物是燃煤电厂污染物控制的难点.三河电厂通过技术集成进行“近零排放”技术攻关,包括采用低低温静电除尘器以提高细颗粒物的除尘效率、利用脱硫除尘一体化技术提高脱硫系统的协同除尘性能、通过湿式静电除尘器实现细颗粒物的深度控制.结果表明:三河电厂通过技术攻关和集成应用后,4台燃煤机组先后实现ρ(烟尘)、ρ(SO₂)和 ρ(NO_x)分别低于GB 13223—2011《火电厂大气污染物排放标准》中天然气燃气轮机组各自排放限值(5、35和50 mg/m3).其中,1～3号机组排放ρ(烟尘)分别为5、3、2 mg/m3,截至2016年3月15日,4号机组ρ(烟尘)连续265 d在1 mg/m3以下.采用低低温静电除尘技术后,4号机组除尘效率由99.86%升至99.89%,同时可凝结颗粒物前驱物SO₃的脱除效率从25.88%升至46.12%;3号机组采用脱硫除尘一体化技术后,100%负荷下协同除尘效率从34.29%升至87.66%以上,全负荷运行下吸收塔出口ρ(烟尘)稳定在3 mg/m3左右;1号、2号、4号机组在100%负荷下湿式静电除尘器除尘效率分别为77.87%、88.82%、83.60%,2号湿式静电除尘器对PM_2.5、PM₁₀和SO₃的脱除效率分别为98.37%、97.31%和42.23%.      

煤电机组烟尘超低排放改造及其技术经济分析

随着烟尘排放标准的提高和煤电机组在重点地区超低排放改造的兴起,湿式电除尘器(WESP)由于其能够显著降低粉尘、液滴等的排放浓度,并同时解决湿法脱硫系统的浆液夹带问题,逐渐成为烟尘超低排放的主要改造方案之一.结合WESP技术原理及其应用现状,以某600 MW煤电机组采用WESP超低排放改造为例进行技术经济分析,结果表明:WESP对烟尘的去除效率能够稳定达到≥75％,在较好的运行工况下烟尘浓度可以控制在10 mg/m3以下;WESP与其他除尘改造方案相比,运行费用最低,在较长的时间内能够显现出最优的经济性.     

湿式静电除尘技术研究及应用

燃煤烟气细颗粒物排放的高效控制是控制雾霾天气的重要手段之一,为此国家颁布了世界上最严格的标准之一:《火电厂大气污染物排放标准》(GB13223-2011),要求火电厂粉尘排放浓度低于30 mg/m3,重点地区低于20 mg/m3。干式静电除尘器由于反电晕和二次扬尘等问题,对亚微米级颗粒物脱除效率较低,难以完全满足新标准的要求。湿式静电除尘技术(WESP)通过水膜清灰方式代替振打清灰,可有效控制湿法脱硫塔后细颗粒物的排放,实现燃煤烟气细颗粒物的深度脱除。该文详细阐述了湿式静电除尘器在粉尘脱除效率、材料润湿、抗腐蚀特性及多种污染物协同脱除等方面的最新研究进展,重点介绍了湿式静电除尘技术在燃煤电厂中的应用现状,并在此基础上对我国湿式静电除尘技术的发展做了总结和展望。     

布袋除尘+湿式电除尘器改造应用

本文是针对350MW燃煤机组烟尘超净排放改造应用实践进行的论述,介绍了原有布袋除尘器的情况以及存在的问题,并围绕布袋除尘器开展改造方案的论证,提出了布袋除尘器加设湿式电除尘器与脱硫系统协同除尘的方案,介绍了湿式静电除尘器原理以及应用于本工程的技术优势。工程改造后通过性能测试满足性能保证值出口粉尘不大于5mg/m~3,同时SO_3的脱除效率为70.5%,满足不小于70%性能要求。布袋除尘器加设湿式电除尘器与脱硫系统协同除尘实现超净排放,取得了显著的环保效益,也为其他机组的改造提供了应用经验。     

燃煤电厂大气污染物“近零排放”技术研究及工程应用

在燃煤电厂实现大气污染物“近零排放”过程中,烟尘控制技术是关键,通过对除尘、脱硫、脱硝等先进环保技术的系统比较,提出了燃煤电厂大气污染物“近零排放”技术路线. 在地处长三角的国华舟山电厂4号机组采用高效低氮燃烧+SCR(选择性催化还原法)脱硝+旋转电极除尘+海水脱硫+湿式静电除尘的技术路线,ρ(烟尘)、ρ(SO₂)、ρ(NO_x)的实际排放值分别为2.46、2.76、19.80 mg/m3;在地处京津冀的国华三河电厂1号机组,采用高效低氮燃烧+SCR脱硝+低温省煤器+静电除尘(高效电源)+湿法脱硫+湿式静电除尘的技术路线,ρ(烟尘)、ρ(SO₂)、ρ(NO_x)的实际排放值分别为5、9、35 mg/m3. 实践表明,立足国情走煤炭清洁高效利用之路,燃煤电厂可以在低成本下实现大气污染物的“近零排放”. 通过对技术路线优化、低浓度污染物在线测量技术及“近零排放”中存在的一些问题进行分析和探讨,提出了燃煤电厂大气污染物控制技术的研究和发展方向. 估算结果表明,如果全国燃煤机组自2015年起采用“近零排放”技术,5 a内烟尘、SO₂、NO_x年均减排率分别可达19.0%、18.9%、18.5%.      

火电厂超低排放及湿式电除尘器的改造探讨

介绍火电厂超低排放必要性及降低污染物排放技术路线,并结合工程实例介绍湿式电除尘器工作原理、布置设计及整体协同设计等内容。通过介绍,使大家进一步了解火电厂超低排放和湿式电除尘器相关内容,希望对以后的工程实施起到一定的借鉴作用。为了改善大气环境质量,国家发改委、环境保护部、国家能源局联合发文要求有条件的企业将原计划2020年完成的超低排放改造任务提前至2017年前完成。湿式电除尘器作为火电厂烟尘排放控制主要设备之一,其项目的实施尤为重要。因地制宜的选取更加符合条件的湿式电除尘器布置,通过整体协同计算,可以优化设计,减小工作量,节约工期和费用,起到节地、节能的作用,取到良好的经济效益,同时还可以提高湿式电除尘器项目的可行性。火电厂烟尘排放控制技术路线采用湿式电除尘器,经济、运营成本及可靠性等方面优势较大,值得大力推广运用。     

松藻矿务局打通一煤矿锅炉脱硫除尘治理效果显著

松藻矿务局打通一煤矿DZL_4-B-W Ⅱ 4t锅炉脱硫除尘治理工程,最近通过有关部门的验收。 该项目采用脱硫效率高,投资少,维护操作简便,占地面积小的SZC型湿式振弦栅脱硫除尘净化器,用锅炉冲渣水作循环水、氢氧化钠作脱硫剂。经綦江县环境监测站监测,二氧化硫排放浓度为114.7mg/m~3,烟尘排放浓度为75.8mg/m~3,林格曼     

电袋复合式除尘在煤矸石电厂中的应用

通过对目前电厂常用除尘技术进行对比分析,以宁夏宁东煤矸石电厂双电双袋除尘器为例,详细列出其设计参数、运行工况、烟尘排放浓度及除尘效率,分析其除尘效果,得出电袋复合式除尘有机地结合了电除尘和袋式除尘的优点,具有耗电量低、治理成本低、适应性强,不受煤种、烟尘特性影响,除尘效率高的优点;煤质较差的煤矸石电厂采用电袋复合式除尘技术烟尘排放浓度可稳定达到50 mg/m3的标准,满足GB 13223—2003《火电厂大气污染物排放标准》要求;但要达到GB 13223—2011《火电厂大气污染物排放标准》烟尘排放浓度低于30 mg/m3的标准,则应进一步优化运行方式,加强设备的管理维护,进一步提高净化效率,方可满足日益严格的环保要求。     

新型组合脱硫除尘工艺的应用研究

采用新型高效的多电场静电消烟凝并除尘器与湿式除尘器串级组成二级除尘系统,可以有效地治理工业锅炉的烟尘,是改造湿法除尘系统、提高除尘脱硫效率的新方法;测定结果同时表明,电除尘器对系统的脱硫无贡献.     

单筒旋风和湿式除尘技术装置

单筒旋风和湿式除尘技术装置是“七五”科技攻关环保项目专题,是由北京市劳保所、北京工业大学和同济大学等单位联合研究成功、秦皇岛市五金工具西分厂生产的除尘技术系列产品。 XOW型旋风除尘器可在4t/h以下层燃锅炉应用烟尘排放浓度可降低25～30％,其中大多是粒径小于10μm的尘粒,具有除尘效率高,钢耗低,阻力适中和制作维护简单等特点,该系统可进行风量与阻力等     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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