天然气中汞及其化合物的检测系统与分析方法研究＊

准确测定天然气中汞及其化合物的采样方法和分析技术成为近年来一个重要的研究内容。文章对该项技术进行了实验研究，并依据研发的实验装置建立了相应分析方法。实验表明：甲基汞加标回收率为87.5％～92.2％；乙基汞加标回收率为86.5％～92.0％，采用该套检测系统可以对天然气中汞及其化合物进行有效的分离和定量分析。     

带SCR脱硝的燃煤锅炉汞排放状态及控制

使用符合美国Ontario-Hydro方法(OH法)标准的测汞设备,对某一电力集团某台安装了选择性催化还原烟气脱硝装置(SCR)的660MW燃煤机组锅炉进行了汞排放状态及控制的试验研究。结果表明:燃煤发电机组安装了SCR后,原煤中的汞主要被电除尘下的灰吸附,占77.65%,另外12.72%的汞在脱硫产物中,最后有9.6%的汞以烟气形式排放,而底渣中的汞含量非常少。     

汞晕带内汞元素在土壤环境中分布规律的研究

以国内典型汞矿开采区作为研究试点,通过对汞晕带内土壤中汞元素的含量及存在形式的采样实测,分析了汞晕带内汞元素在土壤中的分布规律,为汞晕带内人居健康的保证以及土壤环境修复提供了基础资料。     

大连湾表层沉积物中汞的赋存形态与生物可利用性研究

为了解大连湾沉积物中汞的赋存形态和生物可利用性,对大连湾表层沉积物中总汞(THg)和甲基汞(Me Hg)的含量进行了分析,并采用选择连续提取法对表层沉积物中汞的赋存形态进行了研究,探讨了沉积物中汞的赋存形态与甲基汞的关系。结果表明:大连湾表层沉积物中总汞和甲基汞的平均含量分别为95.1、0.71 ng/g,甲基汞占总汞的比例(甲基化率)为0.76%,与自然背景值相比,沉积物中总汞含量明显受到了人类活动的影响;大连湾表层沉积物中各赋存形态汞比例的平均值由小至大依次为水溶态汞(Hg-w)(3%)<胃酸溶解态汞(Hg-h)(10%)<硫化物结合态汞(Hg-s)(24%)<有机结合态汞(Hg-o)(31%)<强络合态汞(Hg-e)(32%),Hg-e、Hg-o和Hg-s为主要存在形态;沉积物中Hg-w、Hg-h和Hg-o与甲基化率呈正相关,显示Hg-w、Hg-h和Hg-o具有较高的生物可利用性。研究表明,采用选择连续提取法进行沉积物中汞赋存形态的研究,对了解沉积物中汞的生物可利用性具有较好的指示意义。     

大连湾表层沉积物中汞的赋存形态与生物可利用性研究

为了解大连湾沉积物中汞的赋存形态和生物可利用性,对大连湾表层沉积物中总汞(THg)和甲基汞(Me Hg)的含量进行了分析,并采用选择连续提取法对表层沉积物中汞的赋存形态进行了研究,探讨了沉积物中汞的赋存形态与甲基汞的关系。结果表明:大连湾表层沉积物中总汞和甲基汞的平均含量分别为95.1、0.71 ng/g,甲基汞占总汞的比例(甲基化率)为0.76%,与自然背景值相比,沉积物中总汞含量明显受到了人类活动的影响;大连湾表层沉积物中各赋存形态汞比例的平均值由小至大依次为水溶态汞(Hg-w)(3%)<胃酸溶解态汞(Hg-h)(10%)<硫化物结合态汞(Hg-s)(24%)<有机结合态汞(Hg-o)(31%)<强络合态汞(Hg-e)(32%),Hg-e、Hg-o和Hg-s为主要存在形态;沉积物中Hg-w、Hg-h和Hg-o与甲基化率呈正相关,显示Hg-w、Hg-h和Hg-o具有较高的生物可利用性。研究表明,采用选择连续提取法进行沉积物中汞赋存形态的研究,对了解沉积物中汞的生物可利用性具有较好的指示意义。     

燃煤电站烟气脱汞方法研究进展

由于汞对人体健康和生态环境的危害极大,近年来,燃煤电站汞污染问题受到广泛关注。虽然已开发出了大量的脱汞方法,但由于技术和成本问题,这些脱汞方法都没有被大规模推广使用,因此,开发高效低成本的脱汞方法势在必行。基于上述原因,论文对燃煤电站烟气脱汞方法进行了详细阐述。     

易燃液体燃烧烟气在空间不同位置的沉积规律

在搭建的试验房间顶部及墙壁上布置一系列采样板,模拟火灾现场中易燃液体燃烧烟气的蔓延和吸附情况,然后定量提取采样板上吸附的烟尘,并利用GC/MS进行定量成分分析,根据采样板上烟气特征成分的含量,确定易燃液体燃烧烟气在不同空间位置的沉积规律,从而确定火场勘查中物证提取的最佳位置。试验结果表明,火源上部正对火源处为最佳提取位置,同时还可提取墙角处,以及距火源最近的壁面和顶面交汇处的烟尘。     

钢铁企业中低温烟气余热用于制冷的研究

总结和分析了我国钢铁企业中、低温烟气余热回收利用情况.采用(火用)分析方法确定了不同温度烟气余热的合理利用方式,对利用烟气直接驱动的制冷机组提出了改进方法,以提高其热力系数和能源利用(火用)效率.介绍了热风炉烟气余热梯级利用方案,将烟气先用于制冷,再用于预热助燃空气和煤气.     

贵州大方县土壤重金属含量及环境质量评价

结合贵州1∶5万响水等6幅岩溶石山区域地质调查项目,对黔北大方地区不同地层区A层土壤进行采样分析,探讨土壤重金属砷、铬、铅、汞含量及其环境意义。研究区碳酸盐岩地层区土壤中砷、铬、铅、汞含量相对较高,碎屑盐岩地层区土壤中砷、铬、铅、汞含量低;碳酸盐岩地层土壤中砷含量超标明显,铅、铬、汞含量与背景值基本一致。按照国家土壤综合质量评价四级标准,研究区土壤以轻度污染为主。     

易燃液体燃烧烟气沉积物环境时效性研究

设计了一个燃烧收集装置,模拟火灾现场中易燃液体燃烧的烟气蔓延和沉积特点,使易燃液体在装置中燃烧产生烟气,平行定量收集后制备成标准烟气样品,在不同时间及温度条件下放置后,利用GC/MS进行成分分析,以此确定易燃液体火灾烟气沉积物是否存在时效性。实验结果表明,型号对汽油燃烧后生成的成分影响不大,但用量和燃烧时间会造成一定影响;采样位置不同,烟气中各成分比例有很大差别;是否加水对烟尘成分没有明显影响;时间越长,温度越高,成分变化越明显。     

Evaluation on speciation and removal efficiencies of mercury from municipal solid waste incinerators in Taiwan

Two large-scale municipal solid waste incinerators (MWIs) located in Taiwan were selected for conducting flue gas sampling to determine the chemical speciation of mercury by both USEPA Method 29 and Ontario Hydro Method (OHM). In addition, the emission characteristics and removal efficiencies of mercury were evaluated via isokinetic sampling of flue gas upstream and downstream of APCDs. Results indicated that the average removal efficiencies of Hg for MWI-A and MWI-B were 29.56 and 44.70%, respectively. In terms of mercury speciation by USEPA Method 29 and Ontario Hydro Method (OHM), oxidized mercury (Hg2+), in the flue gas was predominant at the inlet of APCD for both incinerators. Less than 30% of mercury in the flue gas existed in the elemental form (Hg0) at APCD inlet. Mercury emitted from the stack also predominated as a form of Hg2+ in MWI-A. Approximately 90% of total mercury emission from the stack existed in the form of Hg2+ for MWI-A. Due to the higher removal efficiency of soluble mercury (Hg2+) in wet scrubber, less total Hg was actually emitted from MWI-B than MWI-A. Regarding the removal efficiency of Hg0 in the flue gas, the APCDs of MWI-A (DSI + FF) had a higher removal efficiency than that of MWI-B (ESP + WS) possibly due to the reduction of Hg2+ which occurred in the wet scrubber.     

Mercury emissions from selected stationary combustion sources in Korea

Mercury emissions from various stationary combustion sources such as coal-fired power plants, oil-fired power plants, industrial utility oil boilers, iron manufacturing plants, and industrial waste incinerators, were measured. The US EPA (Environmental protection agency) method 101A and the Ontario hydro method were used to sample the mercury containing combustion flue gases, at the inlet of the air pollution control devices (APCDs) and at the stack. Collected samples of both gaseous and particulate forms were then analyzed using CVAA (cold vapor atomic absorption) type analyzer. Measurement results from the coal-fired power plant showed percentages of elemental mercury (Hg0) as high as 31.4% and as low as 9.5%. However, the content of Hg0 was in the range of 1.3-3.7% from the industrial waste incinerator. Differences in mercury speciation from various stationary combustion sources are believed to be coming from: (1) difference in the fuel types; (2) difference in the major flue gas compositions (ex. HCl and SOx); and (3) difference in the types of air pollution control devices (APCDs). When the measurement results obtained using different sampling methods were compared, the Ontario Hydro Method gave a slightly higher mercury concentration measurement than that of the US EPA Method 101A.     

Total arsenic, lead, cadmium, copper, and zinc in some salt rivers in the northern Andes of Antofagasta, Chile

Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.     

Mercury emissions from coal-fired power stations: The current state of the art in the Netherlands

About 30% of the electricity produced in the Netherlands is generated by coal, all of which is imported. At the same time, the co-combustion of biomass is becoming increasingly important. For the last 25 years, the fate of the elements/trace elements in general and of mercury in particular has been studied in great detail. It appears that on average 50% of the mercury is removed in the ESP (particulate control) and 50% of the remainder is removed in the flue gas desulphurization (FGD), resulting in a total mercury removal of 75%. If a high dust selective catalytic reduction (SCR for NO(x) reduction) is present, the total removal can be up to 90%. The results indicate that on average the removal of mercury during the co-combustion of biomass is similar to that found for full coal-firing. The conclusion is that a modern coal-fired power station with the above-mentioned flue gas cleaning equipment also removes mercury up to 90%. These cleaning devices are being installed to reduce the emission of particulates, sulphur dioxide and nitrogen oxides. This means that mercury abatement can be increased while meeting the EU regulation for SO(2) and NO(x). The application of Best Available Technique (BAT) for coal-fired installations by 1-1-2008 will lead to a further increase in the construction and operation of FGD and DeNO(x) installations.     

燃气热水器优化设计的探讨

探讨了燃气热水器设计热负荷的确定、热平衡分析、换热计算以及烟气动力计算,讨论了燃气热水器的优化设计,对部分设计参数提出了推荐值。     

Atmospheric mercury deposition in Guizhou, China

The atmospheric deposition of mercury including total gas phase mercury (TGM), gas phase divalent mercury (Hg2+), and gas phase monomethyl mercury (MMHg) was investigated. Samples were collected from central cities and nature reserve areas across the province. Techniques and equipment including moss bags, KCl-coated denuder and GARDIS-1A portable mercury vapor analyzer were employed for sample collection and analysis. The reliability of techniques and analytical methods used for the project was evaluated. The deposition of atmospheric mercury was reported in species in this important mercury polluted province for the first time. The spatial and temporal variability of mercury emissions were investigated and reported. Contribution of coal mercury emissions to the atmosphere mercury deposition of the province was also investigated.     

中小型锅炉烟气脱硫的技术探讨

分析了大气污染中SO2的来源，论述了脱硫的分类及现状，结合我国中小型锅炉介绍了两类烟气脱硫技术，提出发展中小型锅炉脱硫技术的方向及几点建议。     

大型火电机组取消脱硫旁路烟道对配电方式的影响

随着环保要求的提高,国家环保机构要求大型火电厂烟气净化装置尽量不设旁路烟道。为响应国家政策,现阶段大型火电机组烟气基本采用无旁路烟道的设计方案。论文主要描述取消旁路烟道后对脱硫配电方式的影响。     

直燃机烟气余热回收经济与节能性分析

直燃机排烟温度过高,不利于节能,在烟道上加设余热回收装置。对烟气余热回收量及烟道阻力进行了计算,分析了烟气余热回收的经济性和节能性。烟气余热回收系统不仅降低了直燃机排烟温度,还提高了夏季直燃机的一次能源利用率。     

天然气供暖方式与天然气的高效利用

本文分析了天然气供暖方式及其特点,探讨了天然气高效利用的途径、烟气热能利用的技术关键、天然气利用设备的发展趋势及既有天然气锅炉房改造方案。