燃煤电厂飞灰PM_(2.5)中Cu、Zn等重金属物质

选取国内四个焚烧不同煤种的发电厂机组中的飞灰作为研究对象,通过粒度分析仪筛选出了粒径低于2.5、2.5～10、10～30μm共三种粒径下的灰样,对4个电厂飞灰迚行了质量分布频率的分析以及痕量元素富集规律的研究,结果表明:PM2.5的质量频率均在10%以下,2.5μm dp10μm的质量频率占比在40%～50%、dp10μm颗粒的质量频率占比在50%左右;燃煤电厂所产生颗粒的真密度与粒径大小密切有关,颗粒真密度随粒径增大而减小,随粒径减小而增大;燃煤电厂所产生的痕量元素(重金属物质)存在形态较为稳定,其存在形式与燃烧方式和煤的种类无关;燃煤电厂所产生的飞灰中各元素的富集系数大致均为随粒径增大而减小,尤其以Cu表现最为明显。     

煤中主要矿物质在Shell气化炉内的转化过程探究

对飞灰和渣的成分进行分析,发现矿物质中的Al、Fe、Ca元素向渣中富集, K、Na、Si元素向飞灰中富集。进一步分析不同粒径下的飞灰和渣,发现粒径越小的飞灰,元素富集程度越高,主要是煤中的矿物质在气化炉内的转化过程中产生了SiO,并在高温下挥发,并吸附了其他挥发矿物,形成了粒径6.5μm以下的颗粒。通过分析其他粒径的灰渣灰成分,推导了矿物质在气化炉中的转化过程。     

城市垃圾焚烧飞灰物化特性动态分析

以某一垃圾焚烧电厂2017年内不同时期产生的焚烧飞灰为研究对象,对其进行较系统性、动态的物化特性分析。结果表明:焚烧飞灰粉体白度约46、密度约1.88 g/cm~3、颗粒的粒径D50、D90分别约为25μm与76μm。粉体颗粒无固定的形态结构,其中可见针状结构、板片结构与方柱状颗粒。焚烧飞灰中存在氯化钾(KCl)、氯化钠(NaCl)、氧化钙(CaO)、碳酸钙(CaCO_3)等,其主体元素含量分布特征为钙(Ca)>氯(Cl)>钠(Na)>钾(K)>硅(Si)>锌(Zn),同时垃圾焚烧飞灰中含多种重金属元素,且重金属在所检样品中的量化顺序是铅(Pb)>铜(Cu)>铬(Cr)>镉(Cd)。本课题工作可为垃圾焚烧飞灰固废的多元化、绿色化、资源化的利用提供积极的技术支撑与理论指导。     

煤粉炉掺烧生活垃圾对灰渣特性的影响研究

利用小试规模煤粉炉,研究掺烧不同比例生活垃圾对燃煤灰渣特性的影响,主要包括飞灰元素组成、飞灰粒径分布、飞灰形貌、灰熔点和结渣特性等影响变化研究。结果表明,随着生活垃圾掺烧比例的增加,灰分中Ca、Fe、Cl和S元素含量增加,Al、Mg、K、Na、Ti和Si含量降低,飞灰球形颗粒分布减少,层状堆积结构增多;灰渣熔融特征温度呈平缓下降趋势,但变化范围小于2%,影响较小;掺烧量为25%时,飞灰表面发现少量褐色大颗粒。总之,生活垃圾掺烧对燃煤灰渣特性影响很小,该结果为实际煤粉炉开展掺烧生活垃圾试验提供了一定理论基础。     

煤粉炉掺烧生活垃圾对灰渣特性的影响研究

利用小试规模煤粉炉,研究掺烧不同比例生活垃圾对燃煤灰渣特性的影响,主要包括飞灰元素组成、飞灰粒径分布、飞灰形貌、灰熔点和结渣特性等影响变化研究。结果表明,随着生活垃圾掺烧比例的增加,灰分中Ca、Fe、Cl和S元素含量增加,Al、Mg、K、Na、Ti和Si含量降低,飞灰球形颗粒分布减少,层状堆积结构增多;灰渣熔融特征温度呈平缓下降趋势,但变化范围小于2%,影响较小;掺烧量为25%时,飞灰表面发现少量褐色大颗粒。总之,生活垃圾掺烧对燃煤灰渣特性影响很小,该结果为实际煤粉炉开展掺烧生活垃圾试验提供了一定理论基础。     

淮南电厂煤燃烧过程中微量元素的迁移性研究

采用ICP-AES和HG-AFS法分析平圩电厂和田家庵电厂的飞灰和灰渣中微量元素含量,发现不同粒径的燃煤副产品中化学元素成分基本相同.但是,大多数微量元素的含量随粒径的减小而出现增加趋势.燃烧过程中微量元素的迁移规律与元素本身的地球化学性质、元素在煤中的存在形态以及电厂的燃煤设备等有关.对煤燃烧过程中微量元素的挥发程度和迁移规律进行了讨论和总结.     

燃煤电厂脱硫粉煤灰单颗粒研究及元素组成

研究电厂脱硫粉煤灰以粒径在3～45μm的颗粒为主,数量占80%以上,并多是表面光滑的球形微珠,主要的矿物成分是莫来石和石英,它的排放因子达到了2.45 kg/t。脱硫粉煤灰的元素组成选取了Mn、Zn、Cr、Cu、Pb、Ni、Cd七种元素,其中Mn在脱硫粉煤灰中的含量最高,但Mn元素的相对富集因子则小于Zn元素的相对富集因子,说明元素含量高其相对富集因子不一定大,还需要考虑电厂燃烧的煤种中的元素含量,从而来确定元素的富集行为。     

城市生活垃圾焚烧飞灰重金属在磁性作用中浸出行为

对城市生活垃圾焚烧飞灰进行了物理化学特性分析,研究了飞灰在不同浸取液pH值、不同磁场强度条件下的重金属浸出行为。实验结果表明:根据我国危险废物浸出毒性鉴别标准,飞灰属于危险废物;飞灰是晶体矿和非晶体矿的混合物;飞灰是由许多形态不规则,结构疏松的玻璃质颗粒组成的,平均粒径为22.15μm;磁场强度为0.1T,pH=4时,飞灰中被浸出的Pb含量最多;磁场强度为0.1T,pH=2时,飞灰中被浸出的Cr含量最多。因此可以通过调控磁场强度和浸取液pH值,高效回收飞灰中的重金属,实现资源化利用,减少环境污染和危害人类健康的风险。     

新疆油田采出水中固体悬浮颗粒结构和性能研究

多种表征手段结合,研究了新疆油田矿场采出水中固体悬浮颗粒的结构及理化性质,实验结果表明:该矿场采出水中固体悬浮颗粒含量小于80 mg/L,粒径较大颗粒(10μm)占总颗粒的85%以上;加入絮凝剂聚氯化铝后,大量颗粒发生沉降,粒径较大颗粒(10μm)占总颗粒的95%以上,而粒径较小颗粒含量不足5 mg/L;不同粒径分布区间颗粒的Zeta电位不同,较小粒径颗粒(5μm)的Zeta电位较高,溶液状态较为稳定;加入絮凝剂后,Zeta电位降低,导致较小粒径颗粒易于发生沉降;结合电感耦合等离子体发射光谱、X射线荧光及元素分析,可知该固体悬浮颗粒中含有8种非金属元素和22种金属元素,元素C、O、Ca含量最高,加入絮凝剂后,元素Al和一些二价金属元素含量增高;X射线衍射表征技术表明颗粒主要以碳酸钙的方解石和文石以及卤化物形态存在。     

微波消解—FAAS法测定城市生活垃圾焚烧飞灰中的重金属元素含量

城市生活垃圾焚烧飞灰中重金属污染是一个严重的城市环境污染问题,飞灰中都含有哪些重金属污染?本文通过采用微波消解—火焰原子吸收光谱法,对城市生活垃圾焚烧飞灰中主要危害污染物重金属铅、铬、镉,镍、铜、铁等重金属含量进行测定.方法检出限范围为0.001~0.023μg/m L,方法加标回收率98.5%~106.2%,可满足于飞灰样品中重金属元素的分析。     

Trace metal emissions from the Estonian oil shale fired power plant

Emission levels of selected trace metals from the Estonian oil shale fired power plant were studied. The plant is the largest single power plant in Estonia with an electricity production capacity of 1170 MW_e (1995). Trace metals were sampled from the flue gases by a manual method incorporating a two-fraction particle sampling and subsequent absorption of the gaseous fraction. The analyses were principally performed with ICP-MS techniques. The trace metal contents of Estonian oil shale were found to be in the same order of magnitude as of coal on average. The high total particle concentrations in the flue gases of the studied oil shale plant contribute, however, to clearly higher total trace metal emission levels compared to modern coal fired power plants. Although the old electrostatic precipitators in the plant have been partly replaced by state-of-the-art electrostatic precipitators, the majority of the boilers are currently equipped with the old precipitators. The results of the study show remarkably high concentrations of toxic heavy metals in the flue gases (e.g., Pb, Zn, Mn and As: >200 μg/m³ each) and clear accumulation of Pb, Cd, Zn, Tl and As on the fly ash. Additionally, significant portions of some heavy metals (e.g., Hg, Cd, As and Pb) were found in the absorption liquids of the sampling line, indicating the presence of either vaporous metal species or metals condensed on very small particles in the flue gases. The experimental results were interpreted by theoretical modeling using Global Equilibrium Analysis. The modeling could reasonably well explain the experimental results, especially the enrichment of certain trace metals in the fly ash as a result of volatilization/condensation phenomenon.     

电渗析法分离医疗垃圾焚烧飞灰浸出液中重金属

采用电渗析法分离医疗垃圾焚烧飞灰浸出液中重金属,考察了电流密度、液固比、处理时间等参数对重金属移除的影响,并分析了电渗析处理对飞灰特性、重金属形态及其浸出毒性的影响. 结果表明,电流密度0.8 mA/cm2、液固比10(w)和处理时间14 d条件下飞灰浸出液中重金属分离效果最好,11.1% Pb, 42.3% Zn, 56.7% Cd, 38.7% Cu, 7.5% Cr被移除,飞灰中大量NaCl被移除,氯含量从20.43%降低到0.78%,热灼减率从11.1%升高到34.3%,可溶态和碳酸盐态重金属含量降低,飞灰基质减少及不可溶态重金属存在导致残灰中重金属含量增加,Pb和Cd浸出浓度仍超过生活垃圾填埋场的阈值.     

Quality characteristics of Greek fly ashes and potential uses

The main characteristics of fly ash from Greek coal-fired boilers are presented in this paper in relation to its exploitation potential. Both fuel and fly ash samples were collected and analyzed according to the ASTM Standards. Apart from the typical analyses (proximate, ultimate, ash analysis and calorific value), an ICP-AES spectrometer was used for the analysis of heavy metals in the ash. Experimental measurements in order to determine the radioactivity content of raw fuel and the fly ash were carried out as well. A representative fly ash sample from Ptolemais power plant was evaluated and tested as filler in Self-Compacting Concrete (SCC).     

景德镇电厂粉煤灰的理化性质分析与表征

粉煤灰是烧煤发电后产生的一种工业废渣。本文采用Mastersizer2000型激光粒度分析仪、DSC/TG、XRD与SEM等测试手段,对景德镇电厂粉煤灰的理化性质进行了分析和表征。结果表明:景德镇电厂粉煤灰是由平均粒径大小为31.5μm的细微颗粒组成,粒度主要分布在1～100μm;其化学成分主要为SiO2、A12O3与Fe2O3,三者总含量高达84.4%,其次是MgO、K2O、CaO、Na2O;其物相成分主要有石英、莫来石、赤铁矿与玻璃相。     

Analysis of fly ash heavy metal content and disposal in three thermal power plants in India

The study investigates the heavy metal content of fly ash and bottom ash from three major power plants in North India, using flame atomic absorption spectrometry. It also studies the prevalent disposal methods used at these sites. The ashes were analysed for the presence of Cr, Mn, Pb, Zn, Cu, Ni and Co and detectable levels of all were found in both fly ash and bottom ash. The concentrations of Cr and Zn were highest while Co concentration was less. The wet disposal method is used in two of the power plants (site 1 and site 3). Neither of the sites uses ash pond lining in the construction of the ash ponds, hence leaching of the heavy metals is possible. Site 2 has adopted 100% dry disposal system which allows better utilization but incurs additional costs. Better management practices, increased utilization and proper disposal practices need to be undertaken to minimize the adverse environmental impact.     

Production of glass from coal fly ash

The coal fly ash from a Chinese thermal power plant was vitrified after the addition of ∼10 wt% Na₂O. The glass products have suitable viscosity at 1200 °C and displayed a good chemical durability. The heavy metals of Pb, Zn, Cr and Mn were successfully immobilized into the glass as determined by the toxicity characteristic leaching procedure method. Results indicate an interesting potential for the coal fly ash recycling to produce useful materials.     

A study of trace element behavior in two modern coal-fired power plants I. Development and optimization of trace element analysis using reference materials

Analytical methods for solid samples taken from a coal-fired power plant were developed and optimized in order to facilitate a comprehensive series of measurement campaigns aimed at trace metal balance determinations in various coal-fired power plants. Commercial reference materials with certified trace element contents were used as model samples. A procedure which had been previously developed for the analysis of fly ash was found to give good recoveries in the case of both coal fly ash and coal in a two-laboratory intercomparison. This procedure was based on microwave digestion in a mixture of HNO₃ and HF in closed vessels. The digestion of samples of dolomitized limestone and gypsum rock was found to be successful under similar conditions but using a mixture of HNO₃, HCl and HF, although the precision of the determination was not as good as in the case of coal and coal fly ash. The digestion procedures developed and tested in this work can be recommended as simple and uniform methods in the analysis of power plant samples for a number of trace elements, exclusive Hg.     

不同粒径城市垃圾焚烧飞灰中重金属形态分析

城市生活垃圾焚烧处理过程中所含重金属会集中在垃圾焚烧飞灰中排出,且含量较高,因此若要安全处置垃圾焚烧飞灰必须要对其特性进行研究。不同粒径垃圾焚烧飞灰中重金属的含量不完全相同,呈现出一定的变化趋势。重金属的各种形态对其在环境中的迁移和转化也会产生一定的影响。通过分析不同粒径垃圾焚烧飞灰的重金属形态进行研究,可为其安全处理处置提供参考。     

陕西省大型燃煤电厂铅污染防控分析研究

目的根据煤燃烧后产物中铅的迁移分布形态而提出防控重点。方法基于陕西省内大型燃煤电厂排放污染物中的铅排放进行监测分析,通过实验统计数据和现有文献资料。结果飞灰、炉中铅含量高于原煤,说明在燃烧过程中,铅在飞灰、炉渣中进一步富集,且从飞灰与渣中含量比值可知,铅更易于在飞灰中富集。结论对于我省燃煤电厂铅的防控,应主要控制炉渣及飞灰,按相关法律及技术规范的要求进行存放及处置,可以控制其对周围环境的影响。     

六盘水发耳电厂粉煤灰精细化资源综合利用研究

发耳电厂年排灰量3×106 t,排出的粉煤灰直接堆放,利用率为零,对环境造成严重污染。该电厂粉煤灰具有硅含量高、铁含量高、烧失量大、粒度不均匀、质量差、难以利用,但含有铝、钛、镓等有用金属的特点,具有较高的利用价值,需要对其中的硅、铝、铁、钛、镓、锗回收利用,本文对发耳电厂粉煤灰精细化资源综合利用进行了初步研究。