石煤与烟煤的混燃特性研究

利用1 MW循环流化床试验台进行了石煤和烟煤的混燃试验,对燃烧过程中炉膛温度、燃烧效率、成灰特性的数据进行了分析,结果表明石煤与烟煤混燃稳定,燃烧效率较高,灰渣的粒度特性有利于灰渣的综合应用,可为石煤的综合利用技术提供依据。     

循环流化床中含钒石煤料球的焙烧特性试验研究

为避免传统提钒工艺所存在的问题,采用循环流化床钙法焙烧工艺,以添加钙基原料的石煤料球为焙烧原料,在热输入功率为1 MW的循环流化床燃烧试验台上进行了含钒石煤焙烧特性试验,研究了燃烧稳定性、燃烧效率、污染物排放特性、燃烧后灰渣特性和灰渣钒浸出特性.结果表明:在以烟煤为助燃燃料的条件下,石煤料球可以在1 MW循环流化床试验台上稳定焙烧运行,且燃烧效率较高;料球中的钙基添加剂有较好的脱硫作用,但对于高硫石煤,要达到国家污染物排放标准,必须采取尾部烟气脱硫措施;焙烧产物以飞灰为主,飞灰中V2O5浸出率接近70%,表明循环流化床对石煤中的钒矿物具有良好的焙烧氧化作用.     

混燃石油焦CFB锅炉汞排放特性研究

为研究烟煤与石油焦混燃的循环流化床锅炉汞的迁移排放特性,采用安大略法(OHM)对机组布袋除尘器(FF)前后和湿法脱硫装置(WFGD)后的烟气进行取样,并同时对入炉燃料、飞灰、脱硫浆液、清洗水、石膏和脱硫废水进行了取样并分析。通过汞的质量平衡核算得到了汞在燃煤副产物中的分配比例以及汞的迁移排放特性。结果表明:飞灰中排放的汞占总汞排放的62.31%,大约30.38%的汞排放到大气中。FF可以高效地脱除颗粒态汞,对总汞的脱除率可达67.36%。WFGD对可溶性的二价汞脱除性能较好,对总汞的脱除率达24.24%。单质汞的排放因子远大于氧化汞,说明电厂大气汞的排放主要以单质汞为主。     

循环流化床中糠醛渣与煤混燃特性的试验研究

在炉膛尺寸为150 mm×150 mm×2 500 mm的循环流化床燃烧试验台上进行糠醛渣与煤的混燃试验,研究其燃烧特性、尾部飞灰及烟气排放特性。研究表明:糠醛渣掺混质量比例为10%-50%的混合燃料在循环流化床中均可稳定燃烧;随着糠醛渣的掺混比例增加,炉膛上部温度升高,尾部飞灰含碳量下降,而颗粒排放浓度升高;随着流化风速增加,炉膛上部温度升高。密相区的温度升高,CO排放浓度下降,SO2、NOx排放浓度上升;糠醛渣的掺混比例增加,CO排放浓度上升,SO2、NOx排放浓度下降。     

循环流化床中石油焦与煤混合燃烧SO2排放特性研究

在一座0．5MW1循环流化床热态试验装置上进行了石油焦与煤混合燃烧试验，研究了烟气中SO2的排放特性．对于石油焦与煤不同燃料配比，不同锅炉运行参数，如过量空气系数、床温、一次风率、Ca／S比等对烟气中SO2排放浓度的影响规律进行了研究．试验表明：对不同配比的燃料，随过量空气系数和一次风率的增大，SO2排放浓度降低；对于床温有一最佳温度，其SO2排放浓度最低；随Ca／S增大，SO2排放浓度降低。     

循环流化床煤燃烧过程中N_2O_NOx的排放研究

在一个循环流化床热态试验台上,研究了煤燃烧过程中氮氧化物（ＮＯｘ和Ｎ２Ｏ）的生成过程,测试了其沿床层高度方向的浓度变化。试验发现,沿炉膛向上,Ｎ２Ｏ浓度不断增加而ＮＯｘ迅速减少,在炉膛出口处Ｎ２Ｏ达到最大值,且排放量远大于ＢＦＢ。作者对其原因进行了分析,同时研究了运行参数对Ｎ２Ｏ及ＮＯｘ排放的影响。     

石煤含钒灰渣精选流化床燃烧锅炉

石煤是国家一种重要的矿产资源。本文在扼要分析石煤燃烧特性、石煤中钒的赋存分布特点和其焙烧转换特征的基础上,简述了石煤含钒灰渣精选流化床燃烧锅炉技术特征和燃用含钒开化石煤所取得的技术指标及其经济社会效益,证明了本研究所开发研制的石煤含钒灰渣精选流化床锅炉是成功的,为有效地综合利用含钒石煤资源开辟了新途径。     

富钒石煤与生物质在CFBC试验台上的混烧实验

针对石煤富钒的特点,利用实验室规模的循环流化床燃烧装置(CFBC),进行了生物质与富钒石煤的混烧实验研究.以期通过富集钒和回收热量达到资源综合利用的目的.实验结果表明:所实验的富钒石煤容易着火,燃烧稳定,燃尽性好,包括与生物质混烧也是如此;经过燃烧后,石煤中的钒大部分转换为五氧化二钒,并在灰渣中富集;石煤颗粒尺度大小、燃烧温度对钒的迁移特性没有显著影响;通过向炉内加入石灰石进行炉内脱硫,当Ca/S摩尔比为3时,烟气中的二氧化硫排放浓度低于国标.     

调整沸腾炉膛结构 改善石煤燃烧

浙江省煤炭资源贫乏,石煤资源相当丰富.随着我国国民经济的迅猛发展,加快了石煤综合利用的步伐.为了充分有效地利用我省石煤资源,六十年代末浙江大学和杭州锅炉厂联合研制成功石煤沸腾锅炉,七十年代初开始批量生产,为石煤资源的综合利用开辟了广阔的前景,目前已发展为产汽、发电、提钒和生产建材的联合产业. 沸腾锅炉是石煤综合利用的关键设备.目前在沸腾锅炉的运行中,普遍还存在着燃     

石油焦燃烧特性研究

石油焦是炼油工艺的副产品,具有低灰分和一定挥发分及高热值的特性,还含有相当多的硫、氮元素和钒、镍等碱金属元素,这些成分在石油焦燃烧时会造成锅炉内腐蚀和污染。在石油焦的利用上,通过燃烧回收热量仍然是主要途径。分别在220t/h煤粉锅炉上和热输入率为0.5MW的循环流化床热态实验装置上进行了石油焦与煤的掺烧实验研究。经过实验对比,认为利用循环流化床技术将石油焦与煤混烧是一种高效、清洁利用石油焦的有效方法。     

煤气化置换燃烧分离CO2模拟分析与研究

基于Aspen plus软件,根据Gibbs自由能最小化原理对煤气化置换燃烧过程进行热力学平衡分析.对徐州烟煤以NiO作为载氧体,研究在常压时燃料反应器温度、水煤比对燃料反应器气体产率和载氧体循环倍率的影响.结果表明燃料反应器温度的降低有利于煤气化产物的氧化;水蒸气用量较少时可得到较高浓度的CO2燃料反应器温度的降低和水蒸气用量的减少将减少载氧体循环倍率.     

Optimization of emissions from fluidized bed combustion of coal,biofuel and waste

Several types of fuel can be burned in a fluidized bed. This paper discusses the impact of low‐ or medium‐volatile fuels (coal) and high‐volatile fuels (biomass and waste) on the emissions of NO, N₂O and other pollutants. It is found that high‐ and low‐volatile fuels behave in different ways, and measures to reduce emissions from coal combustion are not necessarily effective for high‐volatile fuels. This forms a basis for various design options. Copyright © 2002 John Wiley & Sons, Ltd.     

循环流化床锅炉燃烧系统动态特性分析

根据循环流化床锅炉(CFBB)的工作特点以及燃烧系统输入和输出过程变量间的耦合关系,讨论了CFBB的蒸汽压力和床温的动态特性。认为引起蒸汽压力变动的主要原因在于燃料量(内扰)和汽轮机调门的变化(外扰);而影响床温变化的主要因素是给煤量、风量、物料循环量的变动,并从传热和燃烧过程分析了这些因素间的相互耦合关系。这对CFBB燃烧自动控制系统的设计与调试,以及整个控制系统的可靠运行都至关重要。     

A review on devolatilization of coal in fluidized bed

Devolatilization is an important step in fluidized bed combustion and gasification of coal. ‘Devolatilization’ is a general term that signifies the removal of volatile matters from the coal matrix. It is an extremely important step because the combustion of volatile matter can account for 50% of the specific energy of fluidized bed combustion of a high‐volatile coal. Significant insights into the complex physicochemical phenomena that occur during devolatilization have been obtained in the recent years. This review focuses on the devolatilization of coal in an inert gas, air, and oxygen‐enriched air, with emphasis on the effects of the operating parameters (e.g. temperature, heating rate, pressure, and gas velocity) on the yield of volatile matter. Particle size, oxygen content of the fluidizing gas, volatile content of coal and specific heat are some of the other important parameters for the devolatilization of coal. This review also explains the development and application of structural and empirical models. The structural models (e.g. FG‐DVC and CPD models) are fairly complex. However, they can accurately predict the yields of gas and tar. It is observed from the review of the literature that the mechanism of coal devolatilization needs further study. Although the shrinking‐core model can describe the devolatilization in the beginning and toward the end of the process, major deviations are often observed. The economic studies reveal that the capital cost of fluidized bed combustion reduces upon doubling the capacity. Some problems associated with bubbling fluidized bed combustion (e.g. the increase in freeboard temperature) have been explained with the present knowledge of devolatilization. Copyright © 2011 John Wiley & Sons, Ltd.     

The simulation of influence of different coals on the circulating fluidized bed Boiler’s combustion performance

The combustion performance of the boiler largely depends on the coal type. Lots of experimental research shows that different fuels have different combustion characteristics. It is obvious that fuel will change the whole operating performance of Circulating Fluidized Bed Combustion (CFBC). We know even in a pilot-scale running boiler, the measurement of some parameters is difficult and costly. Therefore, we developed the way of simulation to evaluate the combustion performance of Chinese coals in CFB. The simulation results show that, different coals will result in different coal particle diameter and comminution depending on their mineral component and the change will affect the distribution of ash in CFBC system. In a word, the computational results are in accordance with experimental results qualitatively but there are some differences quantitatively.     

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.     

竹园污泥焚烧污染物排放特性的试验研究

选取上海竹园污泥,将原始污泥样品分为全干污泥、均匀干化污泥(含水率10%)和干湿混合污泥(含水率20%,干湿污泥质量比例为10∶3)三种样品,分别送入小型流化床焚烧炉中焚烧。试验研究了全干污泥在750℃、850℃、950℃三个工况下的燃烧特性,并研究了均匀干化污泥和干湿混合污泥在850℃工况下的燃烧特性。研究发现,上海竹园污泥在小型流化床焚烧炉中燃烧时,排放的主要常规污染物包括CO、SO2、NOx、HCl等以及二噁英和Cd、Hg、Pb等重金属。不同燃烧温度和含水率对污染物的排放有一定影响,提高燃烧温度,CO、SO2、NOx、HCl等的排放基本呈现出下降趋势,而烟气中Pb的排放随着温度上升而升高,相同燃烧温度下含水率升高能降低二噁英的排放总量,随着含水率的提高飞灰中重金属含量有所降低,而底渣中重金属含量呈上升趋势。     

Modeling of single coal particle combustion in O2/N2 and O2/CO2 atmospheres under fluidized bed condition

A one-dimensional transient single coal particle combustion model was proposed to investigate the characteristics of single coal particle combustion in both O₂/N₂ and O₂/CO₂ atmospheres under the fluidized bed combustion condition. The model accounted for the fuel devolatilization, moisture evaporation, heterogeneous reaction as well as homogeneous reactions integrated with the heat and mass transfer from the fluidized bed environment to the coal particle. This model was validated by comparing the model prediction with the experimental results in the literature, and a satisfactory agreement between modeling and experiments proved the reliability of the model. The modeling results demonstrated that the carbon conversion rate of a single coal particle (diameter 6 to 8 mm) under fluidized bed conditions (bed temperature 1088 K) in an O₂/CO₂ (30:70) atmosphere was promoted by the gasification reaction, which was considerably greater than that in the O₂/N₂ (30:70) atmosphere. In addition, the surface and center temperatures of the particle evolved similarly, no matter it is under the O₂/N₂ condition or the O₂/CO₂ condition. A further analysis indicated that similar trends of the temperature evolution under different atmospheres were caused by the fact that the strong heat transfer under the fluidized bed condition overwhelmingly dominated the temperature evolution rather than the heat release of the chemical reaction.     

Influence of mineral transformation on emission of particulate matters during coal combustion

Combustion of pulverized coal was studied in a drop tube furnace to understand coal mineral properties with the emission of particulate matters (PM). Experimental conditions were selected as follows: coal particle size was smaller than 63 μm; reaction temperature was 1 100°C, 1 250°C and 1 400°C respectively; oxygen content was 20% and 50% respectively. PM was collected with a 13-stagelow pressure impactor (LPI) having an aerodynamic cut-off diameter ranging from 10.0 μm to 0.03 μm for a size-segregated collection. Such properties as concentration, particle size distribution and elemental composition of PM were investigated. The experimental results indicate that the emitted PM has a bimodal distribution having two peaks around 4.0 μm and 0.1 μm. Increasing temperature leads to the formation of more PM; varied oxygen content leads to much change of emitted PM. PM was also subjected to XRF analysis to quantify the elemental composition. The results show that PM of 0.1 μm is rich in sulfates. Meanwhile, SiO₂ and Al₂O₃ are prevalent in PM of 4.0 μm, which means that the last peak around 4.0 μm is mainly aluminosilicate salts. Translated from Proceedings of the CSEE, 2005, 25(22): 104–108 [译自: 中国电机工程学报]     

石油焦循环化床燃烧技术的应用

石油焦循环流化床燃烧是石油化工企业解决石油焦出路的主要途径。文章介绍了石油焦的燃烧特性和国内外纯浇石油焦循环流化床锅炉及其运行存在的问题，指出了石油焦循环流化床锅炉设计应重点研究的热力参数和关键技术，为石油焦循环流流化床燃烧技术的发展提出了一些合理化的建议。