混合垃圾燃烧特性的实验研究

针对我国目前垃圾焚烧以烧原生垃圾为主的特点，以热重分析和流化床燃烧实验台为主要研究手段，对于混合垃圾的燃烧特性展开深入研究并将二者的试验数据进行了对比。认为：混合垃圾在热重分析仪中的燃烧特性可以用单组分物质的叠加来表示，而混合的垃圾在流化床中燃烧时，用简单的单组分叠加来表示不很合理。图3表5参5     

SO2 emission characteristics and BP neural networks prediction in MSW/coal co-fired fluidized beds

The SO₂ emission characteristics of typical MSW components and their mixtures have been investigated in a Φ150mm fluidized bed. Some influencing factors of SO₂ emission in MSW fluidized bed incinerator were found out in this study. The SO₂ emission is increasing with the growth of the bed temperature, and it is rising with the increasing oxygen concentration at furnace exit. When the weight percentage of auxiliary coal is being raised, the conversion rate of S to SO₂ is largely going up. The SO₂ emission decreases if the desulfurizing agent (CaCO₃) is added during the incineration process, but the desulfurizing efficiency is weakened with the enhancement of the bed temperature. The fuel moisture content has a slight effect on the SO₂ emission. Based on these experimental results, a 12×6×1 three-layer BP neural networks prediction model of SO₂ emission in MSW/coal co-fired fluidized bed incinerator was built. The prediction results of this model give good agreement with the experimental results, which indicates that the model has relatively high accuracy and good generalization ability. It was found that BP neural network is an effectual method used to predict the SO₂ emission of MSW/coal co-fired fluidized bed incinerator.     

燃烧高水分低热值燃料的内旋流流化床燃烧技术研究

内旋流型流化床炉利用非均匀布风产生高温气－固两相旋流，使燃料在炉内运动、相互碰撞、干燥、破碎、燃烧，并可通过改变布风控制燃料加热与挥发份析出速率、燃烧温度与热负荷，适合多种高水分劣质煤及城市垃圾的洁净燃烧，是一种高效低污染流化床燃烧技术。本文研究该型燃烧器床内空气运动、燃烧、传热及排放规律，发展新型清洁燃烧技术。     

城市垃圾典型组分流化床燃烧特性的试验研究

在电加热流化床炉中研究了典型垃圾可着火组分挥发份析出及焦炭燃烧特性，并考察了水份、床温等因素对燃烧的影响，同时还研究了垃圾中高水份组分的焚烧特点。研究表明：聚合物类份的析出可加速焦碳的燃烧；生物质类废弃物焦碳的表观燃烧速率随直径的增大而减小；高水份组分焚烧时间与等效表面积-体积直径成正比。研究结果可为了解垃圾焚烧特性提供基础数据。图11表l参7     

A particulate model of solid waste incineration in a fluidized bed combining combustion and heavy metal vaporization

This study aims to develop a particulate model combining solid waste particle combustion and heavy metal vaporization from burning particles during MSW incineration in a fluidized bed. The original approach for this model combines an asymptotic combustion model for the carbonaceous solid combustion and a shrinking core model to describe the heavy metal vaporization. A parametric study is presented. The global metal vaporization process is strongly influenced by temperature. Internal mass transfer controls the metal vaporization rate at low temperatures. At high temperatures, the chemical reactions associated with particle combustion control the metal vaporization rate. A comparison between the simulation results and experimental data obtained with a laboratory-scale fluid bed incinerator and Cd-spiked particles shows that the heavy metal vaporization is correctly predicted by the model. The predictions are better at higher temperatures because of the temperature gradient inside the particle. Future development of the model will take this into account.     

Co-firing of Thai lignite and municipal solid waste (MSW) in a fluidised bed: Effect of MSW moisture content

Co-firing investigation of a high-moisture-content municipal solid waste (MSW) with Thai lignite have been performed in a laboratory-scale fluidised bed to study the effects of MSW moisture content on the combustion and emission characteristics of major gaseous pollutants. In this study the comparison of 35%- and 60%-moisture MSWs were tested. The results show that the bed temperature in the case of 35%-moisture content is higher than for in case of 60%-moisture content due to the difference of physical properties of the fuel. The combustion efficiency for the case of 35%-moisture MSW is higher than that for 60%-moisture MSW due to higher bed temperature at lower waste moisture content. The synergistic effect of the co-firing of lignite with MSW reduces the emission of CO leading to increase in combustion efficiency. CO concentration for the case of 35%-moisture content is generally lower, and is much less sensitive to the level of excess air. Both the concentration values of SO₂ and the fuel-S converted are lower for lower moisture content waste, particularly at high mass fraction of waste. The fuel mixture with low-moisture in waste gives higher fuel-N conversion to NO whereas the fuel-N conversion to N₂O is higher for higher moisture content waste, particularly at high excess air.     

Description,applications and numerical modelling of bubbling fluidized bed combustion in waste-to-energy plants

The use of the fluidized bed combustor (FBC) has increased. It began in the 20th century as coal combustion and gasification, which then developed into catalytic reactions. Only recently, the application field has been extended to the incineration of biomass and pre-treated waste, for either power generation or waste disposal. The success of fluidized bed combustion is due to high combustion efficiency, great flexibility when it comes to the heating value of the fuel and reduction in pollutants emitted with the flue gas.     

Characteristics of co-combustion and kinetic study on hydrothermally treated municipal solid waste with different rank coals: A thermogravimetric analysis

This study presents an investigation on the influence of hydrothermally treated municipal solid waste (MSW) on the co-combustion characteristics with different rank coals, i.e. Indian, Indonesian and Australian coals. MSW blends of 10%, 20%, 30% and 50% (wt.%) with different rank coals were tested in a thermogravimetric analyser (TGA) in the temperature range from ambient to 700 °C under the heating rate of 10 °C/min. Combustion characteristics such as volatile release, ignition and burnout were studied for the blend fuel. Different ignition behavior was observed depending on the blends composition and the coal rank. The result of this work indicates that the blending of MSW improves devolatization properties of coal. But it was found that the co-combustion characteristics of MSW and coal blend cannot be predicted only from the pyrolytic and or devolatization phenomena as the other factors such as the coal quality also plays a vital role in deciding the blends co-combustion characteristics. The TGA combustion profiles showed that the combustion characteristics of blends followed those of parent fuels in both an additive and non-additive manners. These experimental results help to understand and predict the behavior of coal and MSW blends in practical applications.     

Development of a low-temperature two-stage fluidized bed incinerator for controlling heavy-metal emission in flue gases

This study develops a low-temperature two-stage fluidized bed system for treating municipal solid waste. This new system can decrease the emission of heavy metals, has low construction costs, and can save energy owing to its lower operating temperature. To confirm the treatment efficiency of this system, the combustion efficiency and heavy-metal emission were determined. An artificial waste containing heavy metals (chromium, lead, and cadmium) was used in this study. The tested parameters included first-stage temperature and system gas velocity. Results obtained using a thermogravimetric analyzer with a differential scanning calorimeter indicated that the first-stage temperature should be controlled to at least 400 °C. Although, a large amount of carbon monoxide was emitted after the first stage, it was efficiently consumed in the second. Loss of the ignition values of ash residues were between 0.005% and 0.166%, and they exhibited a negative correlation with temperature and gas velocity. Furthermore, the emission concentration of heavy metals in the two-stage system was lower than that of the traditional one-stage fluidized bed system. The heavy-metal emissions can be decreased by between 16% and 82% using the low-temperature operating process, silica sand adsorption, and the filtration of the secondary stage.     

循环流化床煤与生活垃圾混烧过程中HCL的排放

在０．２ＭＷｔｈ循环流化床上进行垃圾与煤混烧实验．测量ＨＣｌ排放浓度,探讨城市生活垃圾掺烧比率和床层温度对ＨＣｌ排放浓度的影响．实验结果显示,在混烧过程中,随垃圾加入量的增加。ＨＣｌ排放量增加,温度对ＨＣｌ排放浓度的影响很小。垃圾中Ｃａ／（Ｓ＋０．５Ｃｌ）摩尔比对ＨＣｌ自脱除有影响．采用三相流态化垃圾净化系统时,ＨＣｌ在尾气净化系统中的脱除效率高于８０％。     

内旋流流化床垃圾焚烧炉及其研究中的测量技术

内旋流流化床具有燃烧迅速、温度均匀、排放清洁、燃烧过程可控等特点,是一种适合于焚烧城市生活垃圾及其它特种燃料的炉型。包括内旋流流化床锅炉在内的许多流化床锅炉的床料颗粒空隙率小,光线不能穿透;并且颗粒的尺寸大,动量高,其环境难以满足通常测量手段的基本要求。尤其在颗粒相和气相速度场以及其相互作用规律研究上缺乏理想的测量手段。本文介绍了力学研究所建造的内旋流流化床炉,总结了在进行内旋流流化床垃圾焚烧炉试验过程中所采用的部分测量方案     

Energy from municipal solid waste: A comparison with coal combustion technology

The conversion of municipal solid waste (MSW) to energy can conserve more valuable fuels and improve the environment by lessening the amount of waste that must be landfilled and by conserving energy and natural resources. The importance of utilizing MSW was recognized in the 1991 U.S. National Energy Strategy, which sought to “support the conversion of municipal solid waste to energy.” One route to utilizing the energy value of MSW is to burn it in a steam power plant to generate electricity. Coal has long been the predominant source of energy for electricity production in the U.S.; therefore, a considerable science and technology base related to coal combustion and emissions control can be, and has been, applied with substantial benefit to MSW combustion. This paper compares the combustion of coal and MSW in terms of fuel characteristics, combustion technology, emissions, and ash utilization/disposal. Co-combustion of coal and MSW is also discussed. MSW issues that can be addressed by research and development are provided.The major environmental issues that designers of MSW combustion systems have had to address are emissions of trace organic compounds, particularly polychlorinated dioxins and furans, and trace elements such as mercury, lead, and cadmium. Emission of trace organics is generally the result of a poorly designed and/or operated combustion system; modern MSW systems use good combustion practices that destroy organic compounds during the combustion process. Proper control of air/fuel mixing and temperature, and avoidance of “quench” zones in the furnace, help to ensure that potentially harmful organics are not emitted. Computer codes and other design and troubleshooting tools that were developed for coal combustion systems have been applied to improve the performance of waste-to-energy systems.Trace element emissions from both coal and MSW combustion result primarily from vaporization of elements during the combustion process. Most of the trace elements that are vaporized condense on fly ash as the combustion products cool downstream of the furnace and can be effectively controlled by using an efficient particulate removal device. However, volatile elements, particularly mercury, are emitted as a vapor. Several mechanisms are available to capture mercury vapor and some are in use. The development of satisfactory control technology for mercury is a topic currently of high interest in coal burning.The potential for leaching of trace elements and organics from MSW residues after disposal raises issues about the classification and management of ash. Results of laboratory leaching tests, especially for lead and cadmium, have not been consistently supported by field experience. Careful interpretation of the available test protocols is needed to make sure that residues are properly managed.Because of the large scale of coal-fired boilers for electricity production, co-firing of MSW with coal in such boilers could consume large quantities of waste. Several short-term demonstrations have shown that co-firing is feasible. The issues involved in co-firing are emissions of trace elements, trace organics, and acid gases; boiler slagging and fouling; and long-term effects, such as corrosion and erosion of boiler tubes.Areas where research and development has contributed to improved MSW combustion include (a) the formation mechanisms of polychlorinated dioxins/furans, especially low-temperature, catalytic mechanisms, (b) methods of combustion air distribution in incinerators that result in better combustion and reduced emission of organic compounds, (c) the use of gas reburning to control NOx and reduce emission of organic compounds, (d) practical methods for removing organic compounds and mercury from MSW flue gas, (e) the performance of electrostatic precipitators in removing MSW fly ash, particularly when co-firing MSW and coal in existing coal-fired boilers, and (f) burning MSW in fluidized beds or of pulverizing refuse-derived fuel and firing it in suspension-fired, pulverized coal boilers.     

循环流化床中木屑与煤混烧特性的试验研究

在自行研制的炉膛尺寸为150 mm×150 mm×2 500mm的小型循环流化床上进行木屑与煤的混烧试验,研究其燃烧特性及污染物排放特性。结果表明:木屑与煤质量比为1∶3、1∶5和1∶7的混合物能在循环流化床中稳定燃烧;随着木屑混合比例的增加,燃烧高温区往上移动,炉膛温度分布曲线呈"抛物线"型;随密相区温度升高,NOx体积分数增加。在相同流化风速下,随木屑混合比例增加,CO体积分数增大,SO2、NOx体积分数则降低。     

燃煤循环流化床模型与试验研究

利用循环流化床内气－固两相流动等基础方面的研究成果,根据本文床内气固浓－淡流动模型,建立适用不同结构参数的循环流化床燃烧模型,考虑了床内气体、固体颗粒的返混、循环过程,以及煤燃烧、ＮＯ的生成和分解、颗粒磨损等因素。在循环流化床燃烧试验台上进行实验研究,模型仿真结果和实验数据吻合良好,表明气固两相浓－淡流动模型所建立的循环流化床燃烧系统模型可以正确地模拟循环流化床的燃烧过程。     

Theoretical performance analysis of the multi‐stage gas–solid fluidized bed air preheater

The multi‐stage fluidized bed can be used to preheat the combustion air by recovering the waste heat from the exhaust gas from industrial furnaces. The dilute‐phase fluidized bed may be formed to exclude the excessive pressure drop across the multi‐stage fluidized bed. But, in this case, the solid particles do not reach to the thermal equilibrium due to relatively short residence time in each layer of fluidized bed. In this study, a theoretical analysis on the dilute phase multistage fluidized bed heat exchanger was performed. A parameter related to the degree of thermal equilibrium between gas and solid particles at the dilute‐phase fluidized beds was derived. Using this parameter, a relatively simple expression was obtained for the thermal efficiencies of the multi‐stage fluidized bed heat exchanger and air preheater. Copyright © 2001 John Wiley & Sons, Ltd.     

内旋流流化床燃烧系统设计研究

根据垃圾的热值和物理成分分析,结合流化床布风的冷态实验结果,对内旋流流化床燃烧系统进行了研究,设计出热态试验装置并成功地进行了生活垃圾焚烧试验。     

金华城市生活垃圾焚烧发电可行性研究

通过对金华市区垃圾产量和处理现状调研表明,金华市城区城市生活垃圾的日产量在450t／d以上．并以15％的年增长速度增长。随着城市化进程的加快,原有的垃圾填埋场即将饱和,而新的垃圾填埋场选址困难,垃圾焚烧处理是一条比较可行的无害化、资源化的减客手段。以煤作为辅助燃料,提高入炉垃圾的热值,进行清洁焚烧发电是可行的。因此,采用流化床焚烧发电技术,结合浙江八达金华热电有限公司的原有设备和人员,垃圾焚烧后发电供热,实现变废为宝、资源综合利用的目标。     

城市生活垃圾循环流化床处理技术的研究进展

简要分析了国内外采用分类回收及综合利用、卫生填埋、堆肥和一般焚烧方法处理城市生活垃圾的不足之处以及采用循环流化床燃烧技术的优越性,重点介绍了国内外采用循环流化床燃烧装置焚烧城市生活垃圾的研究和应用现状,并对城市生活垃圾循环流化床气化熔融焚烧处理技术进行了简单介绍,指出了目前存在的问题及努力的方向．     

The influence of alkaline catalysts on combustion of coal particles

With increasingly stringent environmental limitations, it is essential to develop and study low-emission combustion techniques such as fluidized bed combustion. In this work, an experimental work was carried out to study the influence of minerals on combustion characteristics of Tabas coal in a one-stage fluidized bed. The results showed that the alkaline minerals have a significant influence on the combustion behavior of coal particles, especially at higher temperatures. It was also found that the residence time has a significant role in both the higher thermal energy and char conversion, due to a considerable increase in the rate of reactions especially at the beginning of the process.     

典型生活垃圾流化床焚烧炉PCDD／Fs的生成与排放控制

为了评估生活垃圾流化床焚烧炉的运行条件对PCDD／Fs生成与排放的影响,在不同燃烧温度和活性炭喷射条件下,分别对4个不同处置能力的典型流化床焚烧炉系统不同点位的PCDD／Fs进行了采样分析和研究．结果表明：尽管燃烧温度对PCDD／Fs的生成影响很大,但并不是影响二嗯英最终排放的主要原因,烟气流经净化设备时PCDD／Fs的低温异相生成反应是二嗯英超标排放的主要原因．布袋除尘器的使用年限对PCDD／Fs的排放控制有重要影响,新安装的布袋除尘器能够很好地控制PCDD／Fs的排放,较旧的布袋除尘器由于“记忆效应”,其PCDD／Fs的脱除能力较弱,甚至会产生负的脱除效率．