垃圾焚烧中抑制二噁英二次生成的方法探讨

根据生活垃圾焚烧技术中二噁英的生成机理,余热锅炉的烟气在低温区急冷可以避免二噁英在低温区的再次合成,但是目前的余热锅炉烟气低温区急冷的不可行,提出从垃圾焚烧系统设计上进行烟气的急冷,抑制二噁英低温区二次生成的新方法。     

不同原料垃圾类型焚烧二噁英特征分布

采用同位素稀释高分辨气相色谱-高分辨质谱法,对烟气中二噁英进行提取、净化和HRGC/HRMS分析,对样品中4～8氯取代的二噁英取得定量结果,通过对生活垃圾焚烧和医疗废物垃圾焚烧产生的二噁英的浓度的同系物分布和毒性当量浓度的不同单体对PCDD/Fs的贡献,可以分析垃圾焚烧产生的二噁英的来源是否单一来源或是混合源,还得出将2478-PeCDF作为二噁英的指示物的结论是可行的。     

FORMATION MECHANISMS AND CONTROL STRATEGIES FOR DIOXINS IN INCINERATION PROCESS OF MUNICIPAL SOLID WASTES

Dioxins, which are of the most toxic materials on the earth, are principal emitted from waste incineration process. The molecular structures, toxicity parameters, such as toxicity equivalency factor, tolerable daily intake and physic-chemical properties of dioxins are briefly summarized. Three formation mechanisms of dioxins in waste incineration process, namely as de novo synthesis, mechanisms involving small organic molecular as precursors and homogenous gas phase reaction mechanism are alto reviewed. The influencing factors for dioxins formation during waste incineration process are also discussed. Three major methods for reducing dioxins emission from waste incineration process are discussed based upon the formation mechanisms and influencing factors. A new waste incineration process with low dioxins emission and low hydrogen chloride corrosion has been proposed based on multi- stage unit operation principal according to formation mechanisms of dioxins and potential production location in waste incinerators.     

Stand der Emissionsmeßtechnik im Abgas der Rückstandsverbrennung

State of the art of emission measuring techniques in the flue gas of waste incineration plants. It is necessary to critically consider measuring techniques in the light of new requirements for waste incinerators (17th ordinance dating from Dec. 1990). Selected examples are concerned with the primary components of flue gas: particulate matter and trace metals, organics with total carbon content, and important groups such as organochlorine compounds (e.g. dioxins/furans) and inorganic chlorides (such as hydrogen chlorine). The evaluation concludes by considering manual techniques as well as monitoring systems and measures for quality assurance. Finally, an account of recent developments in the monitoring of ammonia and mercury is presented.     

Emissions monitoring during coal waste wood co-combustion in an industrial steam boiler

Co-combustion tests were performed in a 13.8 MW_th industrial steam boiler, using Greek lignite from Ptolemais reserve, natural waste wood, MDF residues and power poles. Fuel blends were prepared by mixing single waste wood components with lignite in various concentrations. Oxygen concentration and emissions of CO, SO₂ and NO_x were continuously monitored, during the co-combustion tests. Gaseous and particulate samples were collected and analysed for heavy metals, dioxins and furans according to standard methods. The results showed that co-combustion is technically feasible provided that agglomeration problems could be confronted. Low emissions of toxic pollutants were obtained during the co-combustion tests, below the legislative limit values. The lowest values of dioxins and furans were observed during combustion of fuel blends containing MDF, possibly due to inhibition by some nitrogenous components in MDF. No direct correlation was found between emitted PCDD/F and metal compounds, especially copper. Among the measured metals in the flue gases, zinc was the most prominent, while iron was mainly observed in the solid ash samples.     

危险废物焚烧的烟气污染物的控制和净化探讨

危险废物焚烧产生的烟气包括卤化物、硫的氧化物、氮氧化物、重金属、二恶英等。如何处理这些危险废物焚烧产物,达到欧盟EU/2000/76/EC排放标准是本项目的关键。     

飞灰粒径对二恶英降解效率的影响

低温热脱氯工艺是垃圾焚烧炉飞灰中二恶英分解的一种常见技术,一方面可以实现对大部分二恶英同系物地高效脱除,但是另一方面也容易产生额外的二恶英。为了克服该技术的不足,进一步提高降解效率,本文将低温热脱氯工艺与TiO2/MoS2复合催化剂光催化降解技术相结合,研究在两者共同作用下,飞灰粒径对二恶英降解效率的影响。     

Dioxine – Eine Aufgabe für die Umwelttechnik

Dioxins – Task for Environmental Engineering Two decades of the environmental history of dioxins, i.e. of PCCDs and PCDFs, are examined, with the main emphasis being placed on developments in Germany. After a brief consideration of the important, environmentally relevant properties of dioxins, interest is focussed on the course of the Seveso incident of 1976. The environmental effects of dioxins observed in Seveso received global publicity. In the following years our knowledge of the analysis and toxicology of this group of substances greatly improved and the production of dioxins in the aromatics sector of the chemical industry was drastically reduced. In the 1980s, discussions concentrated on the formation of dioxins in waste incineration. The results obtained during this period led to the present situation in which waste incineration is no longer a significant source of dioxin emission in Germany. The greatest known source of dioxins in Germany is in the metallurgical industry. By the year 2000 this dioxin source will also have been largely eliminated.     

垃圾焚烧飞灰处理技术现状与展望

城市垃圾焚烧飞灰是含有大量重金属和二噁英的危险废物,若不妥善处置,将对人类健康和生活环境造成严重影响。目前常用的垃圾焚烧飞灰处理处置方法,综合分析了其特点和优缺点,并指出飞灰烧制陶粒技术和利用UASB和EGSB装置回收重金属技术可同时实现无害化、减量化和资源化,是飞灰处理技术的发展方向。     

Development of an innovative 3-stage steady-bed gasifier for municipal solid waste and biomass

Gasification of biomass, municipal solid waste, waste-derived fuels and residues has been lately gaining in attractiveness as an alternative thermal treatment method to produce power and heat. Presented in this paper is a new, recently patented, 3-stage gasification scheme, designed for all aforementioned types of fuels and for producing a synthesis gas free of tar and dioxins. The proposed 3-stage gasification scheme comprises of three stages: i) pyrolysis, ii) combustion and iii) gasification. The proposed 3-stage gasification scheme is valid for municipal solid waste and any type of biomass despite differences in chemical composition. The innovation of this 3-stage gasification scheme is based on the fact that the transition between normal and reverse operation and vice versa is achieved only by the proper rotation settings of four air blowers, thus creating a new model of gaseous flow management between the three aforementioned stages. The presented model can achieve a safe industrial-scale operation while producing a gas free of harmful components. The proposed gasification model is validated as suitable for small-to-medium scale capacities, achieving an overall electrical efficiency of 30% and minimum environmental impacts well below all existing thresholds, including those set by the Directive 2000/76/EC on solid waste incineration.     

二恶英分解蜂窝催化剂的研制

以二氧化钛为载体,以五氧化二矾和氧化钨为活性组分,辅以多种助剂,挤制成型制备出蜂窝催化剂。所制的蜂窝催化剂轴向压碎强度≥100 N,磨耗≤3%,节距（4～7） mm,壁厚（1.0～1.2） mm,收缩率≤2%,容重(0.5～0.7) g·cm^-3,几何表面积≥500 m²·m^-3,催化活性≥90%。将该催化剂用于净化垃圾焚烧废气二恶英,具有系统压降小、催化活性高和使用寿命长等特点。     

危险废物无害化焚烧处理技术探析

介绍了危险废物焚烧处理过程中产生的主要污染物如二噁英类有机污染物、酸性气体、飞灰、重金属颗粒等,阐述了各种污染物的防治措施,提出了污染物的控制途径,从而实现对危险废物的无害化处理,避免二次污染的发生。     

Use of municipal solid waste incineration fly ash in concrete

With a view of reducing the quantities to be landfilled, the Solvay Company has been working on the development of a new physicochemical treatment for municipal solid waste incineration (MSWI) fly ashes: the Revasol process. This process allows reducing the soluble fraction, fixing heavy metals and eliminating dioxins. This article reports on the characteristics of a treated ash and on its use in concrete. For the latter point, three characteristics were chosen: the compressive strength and the durability of the hardened concrete and its behavior to leaching. From mechanical and durable points of view, the ash incorporated in the concrete behaves like ordinary sand. The leaching tests carried out on the concrete confirm that the process makes it possible to obtain materials without major risks for the environment. Also, these results as a whole suggest that the use of waste in concrete constitutes a potential means of adding value.     

1.5 MW循环流化床锅炉内煤与垃圾混烧的烟气特性

通过对1.5 MW循环流化床锅炉内煤与垃圾混烧产生的烟气中的CO、HCl、SO₂、NO_x、H₂O、二噁英等成分进行在线监测,发现原煤燃烧排放的CO浓度要高于添加垃圾后排放的CO浓度,随垃圾加入比例的增大,不完全燃烧份额增加,相应的CO排放值逐渐提高。由于原煤含硫量远高于垃圾含硫量,因此随着垃圾加入比例的增大,烟气中的SO₂浓度有所降低。烟气中HCl浓度随着垃圾加入比例的增大几乎呈直线增加。而烟气中NO_x浓度则呈现出含量下降的趋势,这证明循环流化床锅炉可以抑制NO_x总量的生成,但N₂O的排放浓度会有所增加。此外,随着垃圾加入比例的增大,烟气中的H₂O和二噁英含量也有所增加,成为该工艺实际应用过程中需要考虑的问题。     

城市垃圾焚烧飞灰中重金属形态及生物有效性研究

随着集中焚烧法逐渐成为我国城市生活垃圾处理的主要方式,焚烧飞灰的安全处置与利用也成为学者普遍关注的问题。由于在填埋过程中受到各种环境要素的影响,垃圾焚烧飞灰中的重金属有可能会发生迁移和转化,重金属形态、毒性也会随之变化。本文对不同粒径城市垃圾焚烧飞灰中重金属的总量、形态及生物有效性进行了研究,为其在安全填埋及资源化利用过程中预测重金属的环境风险提供参考。     

城市生活垃圾成分及其波动对水泥窑的影响分析

就水泥窑处置生活垃圾时,垃圾灰渣成分及其波动对熟料质量的影响进行了分析研究,结果表明:生活垃圾焚烧产生的灰渣可以作为水泥替代原料;垃圾灰渣作为替代原料会带入一些干扰元素,为保证垃圾处置量及熟料质量,需要对垃圾进行均化等处理。     

城市垃圾焚烧飞灰处理技术及其在水泥生产中资源化利用

分析了城市垃圾处理技术的现状和发展趋势;介绍了城市垃圾焚烧飞灰处理技术的发展和资源化利用的紧迫性;阐述了水泥生产中资源化利用垃圾焚烧飞灰的可行性和前景;回顾了国内外水泥生产协同处理固体废物技术的发展历程,并提出了目前亟需解决的一些关键技术。在广泛研究的基础上,明确指出了水泥生产中资源化利用垃圾焚烧飞灰是实现焚烧飞灰资源化利用和无害化处理的重要途径。     

二噁英在垃圾焚烧过程中的产生与控制

介绍了二噁英在焚烧过程中的产生机理及对环境的危害,提出了垃圾焚烧过程中二噁英的有效控制方法。     

Von der Schadstoffquelle zur Schadstoffsenke – neue Konzepte der Müllverbrennung

From pollutant source to pollutant sink – Novel concepts of solid incineration. Until a few years ago, solid waste incineration plants were considered to be major sources of pollutant emission. Meanwhile, by enhancing the effectiveness of combustion and by integration of modern flue gas cleaning techniques, solid waste incineration now leads with regard to emission reducing engineering measures. Harmful effects on the environment no longer originate in the stacks of these plants. Recently, pollutants enriched in flue gas cleaning products have caused disposal problems. These problems can be solved by concentrating the harmful inorganic constituents, above all mercury and cadmium, to a still higher level through wet chemical extraction and removal of the resulting concentrate from the process. Organic pollutants can be conveniently destroyed by thermal treatment. Despite all the objections there are good chances of using solid waste incineration as a pollutant sink and hence as a tool helping to protect our environment.     

城市垃圾焚烧发电污染物处理技术

城市垃圾焚烧发电以其具有明显的减量化、无菌化、资源化等优点,近年来得到了较广泛的应用。然而,垃圾焚烧后产生的酸性气体、二噁英、灰渣及废水等,如果处理处置不慎就会对环境产生二次污染。文章概述了酸性气体、二噁英、灰渣及废水等垃圾焚烧二次污染物的形成机理,并详细介绍了控制垃圾焚烧所产生二次污染物的方法与措施。