流化床垃圾焚烧炉飞灰沉积实验

在自行搭建的小型流化床积灰试验台上选用流化床垃圾焚烧炉对流管束浮灰,模拟焚烧炉烟气环境下开展飞灰沉积实验。首先分析浮灰理化特性,结果表明：随着粒径增大,浮灰中CaO和SO₃含量逐渐降低,而SiO₂和Al₂O₃的含量逐渐增加;碱金属Na和K以及卤素Cl的含量在粒径较小的浮灰中含量最高。其次重点研究了浮灰粒径、烟气温度和换热管表面温度对飞灰沉积特性的影响规律,结果表明：积灰中主要富含Ca、S、Si和Al等元素,积灰中CaO和SO₃含量比浮灰高,而Al₂O₃和SiO₂含量比浮灰低;积灰量随着烟气温度升高而增加;粒径对灰沉积影响作用显著,大粒径灰颗粒难沉积而小粒径灰粒易沉积;管壁温度在600℃时,积灰量最小。积灰中CaO和SO₃的含量随着管壁温度升高而减少,而难熔Al₂O₃和SiO₂的含量随着管壁温度升高而增加。     

载热体加热炉对流受热面中的烟气流速分析

分别介绍了载热体加热炉对流受热面中的无灰燃料最佳烟气流速,有灰燃料烟气的极限流速,空气预热器中烟气流速和空气流速的选取。     

载热体加热炉对流受热面中的烟气流速分析

从传热强度、流动阻力、燃料灰分、炉管磨损、钢材成本、风机电耗、运行费用等角度分析了载热体加热炉对流受热面中的烟气流速,按照投资和运行费用的总和最少的设计准则,通过优化设计计算,给出最佳烟气流速。     

基于对象的燃煤锅炉对流受热面链式管理模式研究

将锅炉对流受热面系统内的工质、烟气、受热面作为节点对象,并将这些节点对象根据各自流程编号划归为对应的工质链、烟气链、受热面链。整个锅炉对流受热面可模拟由这些包含节点对象的链穿插交互而形成的对象集合。探讨了这种管理模式为锅炉对流受热面计算和设计带来的益处。     

循环流化床锅炉炉内受热面磨损研究

循环流化床（CFB）锅炉炉内受热面的磨损占据了泄漏故障中较大比例,是影响机组安全经济运行的突出问题之一。影响炉内受热面磨损的因素很多,本文主要探讨循环流化床锅炉炉内受热面磨损的影响因素及其对策。     

造纸污泥在流化床中的结团特性和污染排放特性研究

研究了高水分、低热值的造纸污泥在流化床中焚烧的两上重要问题：结团和污染特性。考察了运行床温、污泥水分、给料粒径等因素对污泥结团特性的影响;并对污泥在流化床中的焚烧过程进行分析。测定了不同工况下（变污泥水分、床温、过程空气系统）纯烧污泥时ＳＯ２、ＮＯｘ、ＨＣｌ、Ｃｌ２的排放规律以及灰中重金属的排放。     

循环流化床垃圾炉积灰结焦机理及控制方法

随着我国社会经济的发展和人民物质生活水平的提高,城市生活及工业垃圾越来越多。我国生活垃圾特点所导致的焚烧炉积灰和结焦严重影响焚烧炉的连续运行。因此,必须对垃圾焚烧炉积灰结焦过程机理进行研究。以150 t/h循环流化床垃圾焚烧锅炉为研究对象,通过现场勘查采样、燃料及飞灰成分及特性分析及理论模拟,计算了空气预热器部位可燃物含量,研究了高低温区域积灰结焦的主要原因,最后提出了燃料调整、锅炉运行以及改造设备等方面的控制对策。锅炉发生二次再燃时,整个空气预热器内至少存在约3 t可燃物,同时中心筒内结焦已使筒体内径减少约一半。垃圾等燃料粒径大、密度小,易燃烧不充分,TGA试验可表明,低于300℃时,其分解速率较慢。未燃烧完全的垃圾燃料易在降温过程中形成焦油类有机物,而其在低温区域的黏性是空气预热器部位积灰的主要原因。燃料中的碱金属及碱土金属Na、K、Ca等与Cl、S、O形成的低温共熔体则是中心筒部位结焦的主要原因。中心筒加强筋所产生的速度变化和二次回流都会增加颗粒撞击到壁面的可能性,可能是初期诱发结焦的关键性因素之一。控制对策主要包括:完善现有垃圾燃料的给料系统;加强蒸汽吹灰,在空气预热器部位增加部分脉冲吹灰器;在空气预热器位置增加惰性气体保护系统;控制垃圾燃料的掺烧比例;改变中心筒运行温度和提高烟气流速;添加除焦剂,MgO、Fe2O3粉末或高岭土;保证空气和燃料的良好混合避免在高温过热器以及水冷管束位置形成还原性气氛。     

温度和气氛对高K高S糠醛渣灰分的烧结特性研究

糠醛渣的能源化利用是糠醛产业清洁生产和碳减排的有效途径。然而,现有的直接燃烧利用常面临着因糠醛渣高K引起的灰分烧结严重、高S导致的SO_x排放量大和高水含量导致的燃烧效率低等难题。基于此,在管式炉中考察了单一气氛(N₂、CO₂、O₂)和混合气氛(N₂+H₂O、CO₂+H₂O、O₂+H₂O)中糠醛渣灰在不同温度下的烧结特性,并对灰分颜色、收缩率、微观形貌、矿物质成分和K/S释放等特性进行系统分析。灰分热收缩行为显示,随温度升高,灰样收缩率增加;在单一气氛中添加水蒸气能促进灰分烧结。SEM分析发现,在灰分烧结前,其微观结构在低温下已出现熔融和结渣。XRD分析表明,灰分烧结与低熔点矿物生成紧密相关。单一气氛中,高温下N₂促进钾长石生成;CO₂抑制钾长石生成;O₂促进钙铝黄长石和透辉石生成。在混合气氛中,水蒸气的出现促进多种低熔点钾铝硅酸盐生成,如钾长石和白榴石等。XRF分析显示,随温度升高,灰样中K的固留率(G_K)和S的固留率(G_S)降低;在考察的单一气氛中,高温时,N₂中G_K最低;G_S受气氛的影响较小。在考察的复合气氛中,高温时,G_K受气氛影响较小;G_S受气氛影响严重,特别地,O₂+H₂O气氛中G_S最高,S逸散最少。为抑制糠醛渣灰分烧结和K/S元素逸散到气相中,糠醛渣在流化床燃烧过程中应控制运行温度(低于900℃)、降低气氛中N₂的含量。     

生物质锅炉积灰特性与露点腐蚀

以ND钢为研究对象,选取316 L不锈钢为对比材料,主要研究了65 t·h^-1生物质循环流化床锅炉烟气深度冷却条件下的积灰与露点腐蚀耦合特性。对积灰和腐蚀层进行了XRF、XRD、SEM和EDS分析。实验结果表明：实验管件表面沉积物可分为腐蚀层、耦合层和灰沉积层（NH₄Cl、SiO₂和（NH₄）₂SO₄）。耦合层包含了灰沉积物和金属腐蚀产物,且与灰沉积层黏结紧密易剥落;腐蚀层多为金属的氯化物和氧化物,其厚度随实验进口水温降低而降低,当管壁温低于烟气水露点时,ND钢被腐蚀的程度急剧加重。在实验条件下,ND钢的抗露点腐蚀能力弱于316L不锈钢。     

高钠煤灰烧结特性研究进展

中国新疆准东煤具有储量巨大、开采成本低、挥发分高、硫含量低等特点,是优质的动力用煤。但准东煤钠含量高,燃烧利用时易在受热面上形成烧结性积灰,产生严重的结渣,极大限制了高钠煤的开发利用。因此,要实现高钠煤的清洁高效利用,需充分认识高钠煤灰的烧结特性。总结了高钠煤积灰结渣机理,概述了高钠煤灰烧结机制,探讨了二者之间的内在关联。高钠煤在燃烧过程中,煤中碱金属(主要为钠)释放并以Na_2SO_4、NaCl及Na的形式存在于烟气中,与受热面接触并于其上冷凝形成黏性内白层,内白层捕获飞灰颗粒后反应生成低熔点化合物,其烧结温度降低,使锅炉受热面上发生沾污增强型的"沾污烧结"过程。高钠煤灰的烧结过程包含固相烧结、液相烧结和气相烧结3种方式,对煤灰烧结过程的影响因素包括反应温度、化学组成、煤灰粒径、反应气氛、添加剂种类、锅炉设计和锅炉运行工况等。其中添加剂按氧化物种类可分为碱性氧化物和酸性氧化物,一般情况下碱性氧化物可以降低煤灰烧结温度,酸性氧化物可提高煤灰烧结温度。未来对于提高高钠煤灰烧结温度的研究方向可从新型添加剂出发,找到既能固定烟气中的钠,又能与灰渣中的低熔点含钠矿物质反应生成高熔点化合物的单一或混合成分的添加剂。同时,关于钠蒸气对积灰结渣在微观层面上的动态特性的影响机制也需进一步研究。概述了煤灰烧结温度的测量方法,热导率分析法、压力测量法、热机械分析法、筛分法和压降法,其中压降法是目前为止测量烧结温度较为准确的方法。介绍了上海理工大学碳基燃料洁净转化实验室在高钠煤灰烧结特性方面的研究方向,以期为解决燃用高钠煤锅炉积灰结渣问题提供参考。     

Electrokinetic remediation of bottom ash from municipal solid waste incinerator

The electrokinetic remediation was studied to verify the possibility to reclaim the bottom ash from municipal solid waste incineration (MSWI). In Italy, a production of 1 million tons per year of this kind of residue has been estimated, 90% of which is still landfilled. This work shows the results of four electrokinetic remediation tests for the removal of Pb, Cu, Zn, Cd and chlorides, using an open cell with graphite electrodes and without enhancing agents. The four tests have, respectively, been performed at a constant current density of 0.89, 1.67, 2.04 and 2.48 mA cm⁻², with duration of 42, 68, 47 and 40 h. Heavy metals occur in ashes in various forms, such as exchangeable, adsorbed, precipitated, organically complexed and residual phases. In order to determine the nature of any given system, in terms of specific chemical species and pertaining mobilities, sequential extraction analyses have been performed. The release of pollutants was investigated for treated and untreated ash. After treatment, the concentration of pollutants in the leachate was reduced by 31-83%, better results being obtained for chlorides. Both the low amount of heavy metal extracted and the increase of ash pH during the electrokinetic tests, suggest to use enhancing agents or a cation exchange membrane at the cathode, to prevent the precipitation of metals as hydroxides.     

Characterization of solid residues from municipal solid waste incinerator

In China, the generation of municipal solid waste (MSW) incineration solid residues is expected to increase significantly in the future. Because of ever-increasing generation rates and the concentrations of potentially hazardous heavy metals, which may endanger the ambient environment, these solid residues are of particular concern. Thus, such issues have necessitated the study of the characterization of these solid residues. A detailed characterization of five samples of different type of ashes, collected from two types of MSW incinerators located in Shenzhen (southern China), was carried out in terms of chemical composition, morphology, mineralogy and leaching behavior. Results of chemical analysis and leaching tests suggest that the MSW incineration fly ash must be classified as hazardous waste and should be properly managed. Therefore, the results of this characterization would contribute to the development of adequate waste management strategies.     

垃圾焚烧飞灰处置技术研究进展

系统介绍了垃圾焚烧飞灰处理技术和最新研究成果,阐述了垃圾焚烧飞灰处理技术一般可分为固化/稳定化技术和分离萃取技术两大类。其中固化/稳定化技术主要为水泥固化、热处理、化学药剂稳定化及水热处理技术;分离萃取技术主要为生物/化学提取和超临界流体萃取技术。分析了各项技术的优缺点,认为:水泥固化技术成本低,但增容过大;热处理技术有一定的减容效果,但能耗成本过高;化学药剂稳定化技术稳定化程度高,但较难实现多种重金属的同步固化;生物/化学提取技术反应条件温和,但成本较高;超临界流体萃取技术虽能有效实现重金属的回收利用,但其对设备要求过高;而水热处理技术的反应条件虽对设备有一定要求,但其无害化程度高,而且反应产物可以再利用。最后指出,水热法应该是未来具有较大应用潜力的飞灰处理方法。     

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.     

Thermal treatment of municipal solid waste incinerator fly ash using DC double arc argon plasma

In this study, glassy slag was produced by melting fly ash samples without any additives in a thermal plasma reactor, the core of which was a DC double anode plasma torch. After vitrification, there was an obvious change in the microstructural and the mineralogical characterization, an excellent resistance against leaching of heavy metal ions and a significant decomposition rate (99.95%) of PCDD/Fs in TEQ in the produced slag. These results indicate that the thermal plasma vitrification is an alternative technology with high efficiency and energy to dispose MSWI fly ash.     

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。     

Analysis and optimization of municipal solid waste combustion in a reciprocating incinerator

A mathematical model is presented for the combustion of municipal solid waste in a reciprocating incinerator. The most preferable incinerator is determined by detailed simulation and analysis of different incinerator shapes. Furthermore, the optimal design and operating parameters are obtained by analyzing the injection angle and velocity of the secondary air. Both the results of numerical simulation and practical operation show favorable combustion state, low contaminants emission, and suitability for the combustion characteristics of Chinese municipal waste and the treating requirements. This study provides an important reference for the optimizing design and operation of municipal solid waste incinerator.     

Characterisation of bottom ash from municipal solid waste incineration in Catalonia

Bottom ash from municipal solid waste incinerator plants in Catalonia was characterised to investigate some alternatives for its utilisation and their potential environmental impact. After a detailed chemical and mineralogical characterisation, physical and geotechnical properties were investigated. The study focused on the use of bottom ash as an aggregate substitute in pavement applications. The results show that this material may be successfully used as a compacted material in unbound road sub‐bases. According to Spanish Specifications for road construction, bottom ash complies with the technical requirements for sub‐bases. Data obtained from the leaching test satisfy the limit values established by Catalan Specifications for bottom ash utilisation. The use of bottom ash in the envisaged application should therefore not result in any environmental impact. © 2002 Society of Chemical Industry     

城市固体废弃物治理的应用探讨

对我国城市固体废弃物及其污染现状进行了概述和分析,结合实际情况探讨了有效的治理措施及应用。