宁东能源化工基地固体废物中汞含量分布及对环境影响

通过分析宁东能源化工基地各大燃煤电厂以及煤化工厂固体废物样品,研究了固体废物中的汞分布规律及环境影响。结果表明:汞易在脱硫石膏、粉煤灰和气化粗渣中富集,汞浓度分别为0.16、0.24、0.15 mg/kg,而炉渣和气化细渣中的汞含量则相对较低,分别为0.05、0.03 mg/kg。通过化学组成及汞含量数据分析发现,出现这种情况的原因与汞本身易挥发的性质和固体废物的物化性质有关。此外,通过固体废物浸出毒性实验发现,脱硫石膏、粉煤灰、气化粗渣的浸出汞浓度小于浓度限值(0.1 mg/L),而气化细渣因锅炉回用,不参与填埋,汞又不易在炉渣中富集,故总体上宁东能源化工基地的固体废物无汞环境污染倾向。     

基于燃煤电厂超低排放的汞分布特性研究

为掌握超低排放改造后烟气处理装置对汞分布的影响,选择6台有代表性的超低排放火电机组进行现场测试。通过对火电机组入炉煤、炉渣、飞灰、脱硫石膏、末端烟气等样品的测试,得出不同燃烧产物中汞的分布:底渣和湿除出水的汞含量极微;电除尘底灰中的汞所占比重相对较大,平均汞含量占燃烧产物中总汞的比例可达57.97%。依据质量平衡原理,计算出不同超低排放改造工艺路线对汞的协同脱除效率为87.26%~95.60%,并分析了不同污染控制设备对汞排放的影响。     

燃煤电厂周边大气重金属污染特征及来源解析

为探究燃煤电厂周边大气环境中重金属的污染特征与来源,对广东某山区燃煤电厂周边地区环境和污染源的重金属进行测定,分析其污染特征,采用因子分析法和Pb同位素示踪法对环境中的重金属进行来源解析。结果表明,研究区域室内积尘中重金属浓度水平明显高于土壤重金属,污染空间分布与当地气象条件相关。环境空气TSP中重金属主要来自2个污染源,Cd、Pb、As主要来自电厂燃煤,Ca、Mn、Al、Mg主要来自土壤扬尘。TSP、降尘、积尘样品所含的Pb均与电厂采集的煤、炉渣、粉煤灰样品所含的Pb具有同源性,与其他污染源同源性不明显,说明研究区域大气中Pb污染主要来自电厂燃烧所排放的烟尘,其他污染源影响不大。     

南京燃煤电厂烟气中汞的排放调查

对南京市8家国控污染源13台（套）燃煤锅炉进行监测，结果表明，燃煤电厂烟气中汞主要以气相部分汞形态存在，其排放值均达标，为0．16～15．9μg／m3，均远低于标准限值；煤质中汞含量与电厂烟气中汞浓度变化曲线的趋势是大致相似，相关系数为0．91；燃煤电厂机组容量、发电负荷越大，汞平均排放因子呈变小趋势；静电除尘器、湿法脱硫和选择性催化还原法的净化配置对汞的脱除效率最高，达到95．4％。     

火电厂执行大气污染物排放新标准的达标研究

新标准《火电厂大气污染物排放标准》(GB 13223—2011)中现役机组排放限值于2014年7月1日正式执行,与旧标准《火电厂大气污染物排放标准》(GB 13223—2003)相比排放限值大幅趋严,且增加了燃煤电厂汞排放限值。选取具有代表性的电厂锅炉进行手工和在线监测,结果表明,燃煤机组需有高效除尘器和脱硝设施才可稳定达标;燃油机组无法达到标准限值要求,未来应逐步淘汰或改用清洁能源;天然气机组二氧化硫和氮氧化物可以达到该标准要求。建议对燃煤电厂锅炉低负荷下脱硝设施的运行、低浓度下烟尘测定的准确性以及汞排放监测进一步研究。     

燃煤工业锅炉烟气除尘及花岗岩水膜除水器

简要介绍了燃煤工业锅炉排放烟尘的主要参数，除尘技术状况及白银铝厂锅炉烟尘除尘器改为花岗岩水膜除尘器后的应用实效。     

燃煤电厂煤中汞含量对烟气中汞排放水平的影响

对江苏省9家燃煤电厂入炉煤中ω（汞）及烟气中ρ（汞）进行了测试，结果表明，9家燃煤电厂入炉煤中ω（汞）为54．5～297 ng／g，平均值为139 ng／g，低于我国煤中ω（汞）的平均值（220 ng／g）。燃煤电厂排放烟气中ρ（汞）为0．08～16．97μg／m^3，远低于《火电厂大气污染物排放标准》（GB 13223－2011）汞及其化合物标准限值（30μg／m^3）。通过对燃煤电厂入炉煤中ω（汞）与最终排放的烟气中ρ（汞）进行分析，两者之间有一定的相关性。     

浅析城市建成区燃煤锅炉整治的可行性——以镇江市区为例

工业锅炉排放的烟尘和二氧化硫分别占全国总排放量的41.6%和22.2%。主要是因为其燃料在锅炉内燃烧过程中除放出大量热量外,还会产生大量的烟尘。烟尘由气体和固体两部分组成。气体部分主要有二氧化碳、一氧化碳、水蒸气、氮气、氧气、氧化氮、二氧化硫和硫化氢等,固体部分主要是飞灰和炭黑,这是雾霾天气的成因之一。本文以镇江市燃煤锅炉整治为例,浅析城市建成区燃煤锅炉整治的可行性。     

略论小城镇冬季供暖燃煤锅炉的节能减排

小城镇冬季燃煤锅炉能耗高、烟尘排放量大,原因在于锅炉本身燃烧设备技术简陋、司炉工操作技术水平低和锅炉运行时的不合理配风。环保部门在燃煤锅炉运行管理中,只重视烟尘是否达标排放,而忽视了对除尘器下灰处置的监督管理。本文提出了促进锅炉经济运行节能的措施以及使除尘器正常运行进而减少烟尘排放量的措施。     

循环流化床燃煤电厂铅的迁移特性

选取2家燃煤电厂3台循环流化床机组进行现场监测,在不同负荷条件下,采集并分析燃煤、烟气、飞灰、炉渣等样品的Pb含量,通过物料平衡核算,对循环流化床机组各环节Pb的迁移特性进行研究。结果表明:机组负荷变化对烟气、飞灰、炉渣的Pb含量影响不大,烟气Pb排放质量浓度均在2μg/m~3以下。电袋复合除尘处理后,烟气中颗粒态Pb的浓度总体低于气(溶胶)态Pb的浓度。Pb在炉渣和飞灰中均有富集,平均富集因子分别为2.16和3.02。飞灰较炉渣对Pb具有更强的富集能力,布袋灰中Pb含量略高于电除尘灰。循环流化床锅炉燃烧后Pb分布在飞灰、炉渣和外排烟气中的比例分别为62.49%、37.49%和0.02%,Pb释放率低于煤粉炉,在Pb污染控制方面更具优势。除尘过程对烟气中Pb的影响主要表现为飞灰对Pb的吸附和除尘器对飞灰的分离脱除,尤以后者为主。由于烟气中气(溶胶)态Pb所占的比例很低,Pb基本吸附在飞灰上,除尘效率的高低直接决定了Pb的去除效果。     

石河子燃煤电厂重金属排放研究

选取石河子市典型燃煤电厂,对其燃煤烟气重金属排放浓度及飞灰、底渣、脱硫石膏重金属的富集进行定量分析。结果表明,烟气中各重金属排放浓度从高到低依次为Zn、Ni、Cr、Pb、Cu、Hg、Co、Cd、As。各重金属元素在飞灰中的富集程度较高,除Hg、Cd、Ni外,其他重金属元素在飞灰的富集因均值均大于5。其中,As在飞灰的富集因子均值为5.76。研究结果可为石河子重金属污染控制提供基础数据。     

Monitoring the species of arsenic, chromium and nickel in milled coal, bottom ash and fly ash from a pulverized coal-fired power plant in western Canada

The concentration of As, Cr and Ni and their speciation (As3+;5+, Cr3+;6+ and Ni0;2+) in milled coal, bottom ash and ash collected by electrostatic precipitator (ESP) from a coal fired-power plant in western Canada were determined using HGAAS, ICP-AES and XANES. The chemical fractionation of these elements was also determined by a sequential leaching procedure, using deionized water, NH4OAC and HCI as extracting agents. The leachate was analyzed by ICP-AES. Arsenic in the milled coal is mostly associated with organic matter, and 67% of this arsenic is removed by ammonium acetate. This element is totally removed from milled coal after extraction with HCI. Arsenic occurs in both the As3+ and the As5+ oxidation states in the milled coal, while virtually all (>90%) of the arsenic in bottom ash and fly ash appears to be in the less toxic arsenate (As5+) form. Both Ni and Cr in the milled coal are extracted by HCI, indicating that water can mobilize Ni and Cr in an acidic environment. The chromium is leached by water from fly ash as a result of the high pH of the water, which is induced during the leaching. Ammonium acetate removes Ni from bottom ash through an ion exchange process. Chromium in milled coal is present entirely as Cr3+, which is an essential human trace nutrient. The Cr speciation in bottom ash is a more accentuated version of the milled coal and consists mostly of the Cr3+ species. Chromium in fly ash is mostly Cr3+, with significant contamination by stainless-steel from the installation itself.     

燃煤电厂石膏雨污染排放实测

对上海市8台燃煤机组开展了石膏雨和相关污染物排放监测,考察部分燃煤电厂石膏雨排放对周边居民生活和电厂生产造成的影响。结果表明,采用GGH并加热到一定温度,同时对除雾器进行优化的机组烟尘和可凝结颗粒物浓度均较低,石膏雨沉降和液滴均未检出,无冷凝回流液;虽然装有湿式电除尘器和GGH的机组石膏雨沉降未检出,但液滴浓度较高;仅装有湿式电除尘器的2台机组中1台检出石膏雨沉降;对照机组石膏雨沉降和液滴浓度均较高。建议电厂提升排烟温度,同时采取措施消除烟气中石膏夹带,彻底消除石膏雨,在标准制定时应充分考虑目前燃煤电厂多种污染物排放情况及其对环境的影响,尤其是石膏雨和可凝结颗粒物,制定相应的监测方法和评价体系,将其纳入火电厂排放标准中。     

Speciation and mass-balance of mercury from pulverized coal fired power plants burning western Canadian subbituminous coals

This report summarizes the results of a study carried out on six pulverized coal-fired power plants in western Canada burning subbituminous coal for the mass-balance and speciation of mercury. The main objectives of this study were to: determine the total gaseous mercury (TGM) emitted from stacks of power plants using the Ontario Hydro method; identify the speciation of emitted mercury such as metallic (Hg(0)) and gaseous elemental (GEM) mercury; and perform mass-balance calculations of mercury for milled-coal, bottom ash, electrostatic precipitators (ESP) fly ash and stack-emitted mercury based on three tests. Sampling of mercury was carried out using the Ontario Hydro method and mercury was determined using the USEPA method 7473 by cold vapor atomic absorption (CVAAS). The sample collection efficiencies confirmed that both oxidized and the elemental mercury had been successfully sampled at all power plants. The total gaseous mercury emitted (TGM) is 6.95-15.66 g h(-1) and is mostly in gaseous elemental mercury (GEM, Hg(0)) form. The gaseous elemental mercury is emitted at a rate of 6.59-12.62 g h(-1). Reactive gaseous mercury (RGM, Hg(2+)) is emitted at a rate of 0.34-3.68 g h(-1). The rate of emission of particulate mercury (Hg(p)) is low and is in the range 0.005-0.076 g h(-1). The range of mass-balances for each power plant is more similar to the variability in measured mercury emissions, than to the coal and ash analyses or process data. The mass-balance calculations for the six power plants, performed on results of the three tests at each power plant, are between 86% and 123%, which is acceptable and within the range 70-130%. The variation in mass-balance of mercury for the six power plants is mostly related to the variability of coal feed rate.     

Speciation of nickel in Canadian subbituminous and bituminous feed coals, and their ash by-products

The nickel species in the feed coals and ash by-products from seven Canadian power plants (including one with a fluidized bed combuster) burning local subbituminous and bituminous coals with sulfur contents ranging from 0.22 to 3.6% have been examined using nickel XANES spectroscopy. XANES spectroscopy of Ni in coal and coal derived ash is complicated by a poor signal : noise ratio due to fluorescence of the much more abundant iron in the coal. Nevertheless, it has proved possible to show that the Ni environment in coals varies from largely oxidic species to mixtures of Ni-containing oxide and sulfide species. The nickel in one oxidized coal appears to be present as nickel sulfate. Nickel in all bottom and fly ash samples examined appears also to be present largely in oxygen anion environments. With the exception of one fly ash sample, for which the Ni exhibited spectral features similar to those for Ni(2+) in spinel or oxide phases, the nickel in the bottom and fly ash samples appears to exist largely as Ni(2+) in environments similar to those reported for Ni in silicate glasses. The data obtained indicate that the presence of potentially carcinogenic nickel sulfides in ash by-products from combustion of these coals is unlikely.     

典型钢铁企业汞排放水平及排放特征研究

以某典型钢铁企业为研究对象,测定企业废气、废水、固废汞排放水平,并分析汞排放特征。研究表明,球团、烧结、高炉工艺废气排口烟尘中汞排放浓度和排放速率明显低于烟气;汞主要以气态形式排放,烧结工艺排口废气汞最高浓度分别是其他2个排口的7倍和3倍。球团、烧结、高炉、电炉四工艺环节中,烧结汞排放速率占四工艺汞排放速率总和的87%。半干法脱硫、氨法脱硫、石灰石石膏脱硫对废气中汞的去除效率分别为90.0%、78.7%和29.9%。企业废水排放未检出汞,脱硫产生固废汞含量明显高于除尘产生固废汞含量,脱硫灰汞含量是脱硫石膏的15倍。     

Influence of mercury from fly ash on cattle reared nearby thermal power plant

Cattle grazing nearby coal-fired power stations are exposed to fly ash. The present investigation aims to assess the environmental and health impacts of fly ash containing mercury emitted from thermal power plant. The health effect of fly ash were studied using 20 lactating cattle reared within a 5-km radius of s thermal power plant for the possible effect of fly ash such as the alterations in hematological and biochemical parameters of blood, milk, and urine. Results indicated that the hemoglobin levels (6.65?±?0.40?g/dl) were significantly reduced in all the exposed animals. Biochemical parameters viz., blood urea nitrogen (27.35?±?1.19?mg/dl), serum glutamate oxaloacetate transaminase (43.39?±?3.08?IU/l), albumin, and creatinine were found to be increased, whereas serum glutamate pyruvic transaminase (29.26?±?2.02) and Ca²⁺ were observed to be statistically insignificant in exposed animals. Mercury concentrations estimated in the blood, milk, and urine of exposed (n?=?20) and control (n?=?20) animals were 7.41?±?0.86, 4.75?±?0.57, 2.08?±?0.18, and 1.05?±?0.07, 0.54?±?0.03, 0.20?±?0.02?μg/kg, respectively. The significant increase (P?<?0.01) in the levels of mercury in blood, milk, and urine of exposed animals in comparison to control indicated that the alterations of biochemical parameters in exposed cattle could be due to their long term exposure to fly ash mercury which may have direct or indirect impact on human populations via food chain.     

Investigation into the relationship between major and minor element contents and particle size and leachability of boron in fly ash from coal fuel thermal power plants

A basic investigation of boron in discharged fly ash by coal fuel thermal power plants in several worldwide locations was carried out. Eight kinds of fly ash sample were prepared from eight coal fuel thermal power plants. Two of the fly ash samples were used to examine the relationship between the concentration of boron in fly ash and the particle size. When the particle size of fly ash is smaller, there is a possibility that it will be released into the air and spread over a wide area in the environment. However, it has become apparent that fly ash of smaller particle size has a higher concentration of boron and a higher enrichment factor. In other fly ash samples, the boron contents were examined and leaching tests were carried out. There is acidic fly ash as well as alkaline fly ash that contains larger amounts of acidic or basic salts. On alkaline fly ash, when the concentration of boron bound to Fe-Mn oxide is low; it has become apparent that leaching boron is increased in a solution with lower pH of approximately 4 which is nearly the pH of acid rain.