朝鲜无烟煤燃烧特性随升温速率的变化及动力学研究

燃烧特性和燃烧反应动力学参数是燃料用于燃烧装置热力计算、设计和数值模拟必不可少的主要数据。利用同步热重分析仪在空气气氛下以升温速率分别为10℃/min, 20℃/min, 30℃/min升温至1 200℃进行了朝鲜无烟煤(KA)燃烧实验,同时与中国无烟煤(CA)进行对比,并计算得到了KA和CA的燃烧特性指数,采用等转化率的Flynn-Wall-Ozawa(FWO)和Kissinger-Akahira-Sunose(KAS)方法估算了反应动力学参数。结果表明：升温速率对KA和CA的着火性能有重要影响,升温速率越快,KA和CA的着火性能指数提高越明显;KA的燃烧特性指数均低于CA的燃烧特性指数,KA的燃烧特性比CA的燃烧特性差,更难燃烧;KA的平均表观活化能为112.13 kJ/mol,明显高于CA的81.51 kJ/mol,从反应动力学上证明了朝鲜无烟煤燃烧特性较差;对于三种升温速率下最适合的反应机理模型,KA的实验数据与理论模型A3/2,R3和A1拟合良好,而CA的实验数据与A3,A2和A3/2模型拟合良好,表示KA和CA一般遵循随机核形成及生长反应机理,KA的反应级数小于CA的反应级...     

福建无烟煤与玉米芯混合燃烧特性研究

采用热分析仪对福建无烟煤和玉米芯的混合燃烧特性进行了研究,结果表明,无烟煤混合玉米芯后,其着火提前,燃烧和燃尽特性得到改善,但随着玉米芯混合比例的增加,无烟煤后期燃烧特性改善并不明显;此外,采用Coats-redfern法计算了无烟煤和玉米芯不同比例混合燃烧的活化能E,计算结果表明,无烟煤混合玉米芯后,其活化能E降低,但活化能的大小与玉米芯的比例大小无明显关系.玉米芯对无烟煤的燃烧主要起引燃作用.     

几种金属化合物对劣质无烟煤燃烧特性的影响

针对水泥生产特点,选择BaCO3,Fe2O3,CaO3和CaO为催化剂,采用热重法对煤粉中掺入催化剂的燃烧特性进行了实验研究,讨论了不同催化剂和催化剂含量对煤粉燃烧特性的影响,实验结果表明,以添加剂质量计,BaCO3的添加量为1%时,催化效果最为明显,试样的着火温度相比原煤降低了22℃,燃烬温度提前了27℃;Fe2O3的添加量为10%时,催化效果最佳,试样的着火温度比原煤降低了17℃,燃烬温度提前了32℃;CaO3和CaO对煤粉燃烧性能的改善作用不显著,且随着添加量的增加,试样的燃烬性变差.     

碳酸盐对高灰分煤粉燃烧的动力学研究

采用非等温热重分析技术对比研究了Na2CO3，BaCO3和CaCO3对高灰分煤粉（灰分〉44％）燃烧反应动力学参数的影响。非等温热重分析以20℃／min的升温速率从室温升到1000℃，动力学参数采用Coats—Redfern方程进行计算．结果表明：与空白煤样对比，掺有碳酸盐的煤样着火温度均有不同程度的降低，而煤样的最大燃烧速率增大且燃烧最大速率出现的温度前移；当煤粉样品中分别掺有3％的Na2CO3，BaCO3和CaCO3时，煤粉燃烧的活化能比纯煤粉分别降低了15．63％，12．39％和14.23％，且指前因子与活化能之间存在着线形关系，其关系为In（А）=0．2783E-12．882。     

汪清油页岩燃烧反应动力学研究

采用Pyris-1TGA热重分析仪测定汪清油页岩不同升温速率(20,50,80,100℃/min)下的一组燃烧TG曲线,根据Popescu提出的一种新的多重扫描法,将不同机理函数式进行线性回归。结果表明,该油页岩燃烧反应符合三维扩散机理,从而确定了该油页岩机理函数的积分式与微分式,获得了活化能与频率因子的值。取转化率为0.1,0.2,…,0.9,将冉全印-叶素温度积分近似式与所求机理函数结合,利用迭代法求出转化率-温度的理论值。结果发现,理论TG曲线与实验曲线吻合较好,表明了所求得的油页岩燃烧机理函数的合理性。     

水泥窑用无烟煤的催化燃烧

与烟煤相比,无烟煤因其燃烧活性较差,一般不被水泥回转窑、予分解窑采用。本实验以ＣａＣＯ３,ＣａＣＯ３＋ＢａＣＯ３,ＣａＣＯ３＋Ｓｒ（ＮＯ３）２,ＣａＣＯ３＋ＢａＣＯ３＋Ｓｒ（ＮＯ３）２＋Ｆｅ２Ｏ３为催化剂,对有代表性的４种无烟煤进行催化燃烧研究。借助燃烧率测定,Ｘ射线衍射及差热分析等研究方法,讨论了无烟煤催化过程中的相关影响因素。研究表明：实验所用催化剂参与了煤燃烧中的化学反应过程,对无烟煤的燃烧     

芦竹燃烧动力学不同反应机理的研究

利用热重分析仪进行了芦竹的燃烧试验,采用Coats-Redfern法分析热重曲线,研究不同升温速率(10,20,30℃/min)对燃烧过程的影响。结果表明,芦竹燃烧过程可分为3个阶段,即水分析出、挥发分析出与燃烧及焦炭表面燃烧三个阶段。主要反应集中在第二和第三反应阶段。随着升温速率的增大,最大失重速率增大,三个阶段向高温方向偏移。挥发分析出与燃烧及焦炭表面燃烧阶段的反应机理均满足随机成核A3模型,挥发分析出及燃烧阶段的活化能平均值为21.49 k J/mol,频率因子变化为1.31×10³3¹.83×101.83×10³min3min^(-1);焦炭表面燃烧阶段的活化能平均值为47.15 k J/mol,频率因子变化为325×10(-1);焦炭表面燃烧阶段的活化能平均值为47.15 k J/mol,频率因子变化为325×10³3⁷4.9×1074.9×10³min3min^(-1)。     

芦竹燃烧动力学不同反应机理的研究

利用热重分析仪进行了芦竹的燃烧试验,采用Coats-Redfern法分析热重曲线,研究不同升温速率(10,20,30℃/min)对燃烧过程的影响。结果表明,芦竹燃烧过程可分为3个阶段,即水分析出、挥发分析出与燃烧及焦炭表面燃烧三个阶段。主要反应集中在第二和第三反应阶段。随着升温速率的增大,最大失重速率增大,三个阶段向高温方向偏移。挥发分析出与燃烧及焦炭表面燃烧阶段的反应机理均满足随机成核A3模型,挥发分析出及燃烧阶段的活化能平均值为21.49 k J/mol,频率因子变化为1.31×10~3~1.83×10~3min~(-1);焦炭表面燃烧阶段的活化能平均值为47.15 k J/mol,频率因子变化为325×10~3~74.9×10~3min~(-1)。     

果壳生物质燃烧特性与动力学分析

为充分利用果壳生物质废弃物,采用热重分析对油茶壳、核桃壳、澳洲坚果壳进行了燃烧实验研究,考察了不同升温速率下3种果壳生物质的燃烧特性及动力学参数。结果表明：3种果壳生物质燃烧特性不同,但燃烧特性参数均随升温速率升高而增大;随着升温速率的增加,着火点、燃尽温度、最大燃烧速率、平均燃烧速率及综合燃烧特性指数提高;10℃/min时,油茶壳、核桃壳、澳洲坚果壳综合燃烧特性指数分别为0.56×10^-7、1.18×10^-7、0.88×10^-7;3种果壳生物质的燃烧反应遵循一级反应动力学模型,相关系数（R²）均达0.93以上,低温阶段活化能为30.40~52.41 kJ/mol,高温阶段活化能为18.49~40.62 kJ/mol,低温阶段活化能均大于高温阶段。     

无烟煤粉燃烧特性及其对燃烧器和分解炉设计的影响

用从不同的试验装置得到的实验数据,分析几种比较典型的低挥发分固体燃料的燃烧特性,并描述了煤粉在不同的燃烧阶段理论模型的进展,最后结合理论和实验数据提出了强化无烟煤粉燃烧过程的基本原理及方法。     

Evaluation of intrinsic kinetic parameters of coal combustion

A method for evaluating the intrinsic kinetic parameters of coal combustion is presented. The method is based on the theory of diffusion and chemical reactions in porous particles. The intrinsic activation energies evaluated for bituminous coal and chars are in the range 137–204 kJ mol^?1.     

无烟煤化学链燃烧过程燃料氮转化释放特性

基于赤铁矿石载氧体,在小型单流化床反应器上,开展煤挥发分和焦炭的化学链燃烧研究,探讨挥发分氮和焦氮在化学链燃烧过程中的转化特性。研究表明:燃料氮释放的中间产物HCN和NH₃与铁矿石载氧体具有较高的化学反应亲和性,易于被载氧体氧化生成N₂和NO。淮北无烟煤挥发分氮转化过程中,NO是唯一的氮氧化物,反应器出口中间产物NH₃的释放份额略高于HCN。在煤焦化学链燃烧还原过程中,部分燃料氮释放的中间产物HCN和NH₃被铁矿石氧化导致少量NO的生成,还原过程中无N₂O的释放;较高的还原反应温度加速了NO的生成。减少进入载氧体氧化再生过程的焦炭量可减少空气反应器NO和N₂O的生成。     

Influence of the secondary air parameters on the combustion conditions of a tunnel kiln

Conclusions The operating effectiveness of the cooling zone has a significant influence on the fuel consumption in a tunnel kiln, which increases with an increase in the temperature level of firing of the refractories. Acceleration of heat exchange in the cooling zone with improvement in its thermal and gas insulation is an important step in reducing the fuel consumption in kilns.With identical effectiveness of the thermal operation of the cooling zone the parameters of the secondary air supplied for combustion do not have a significant influence on the total fuel consumption in the furnace but do determine to a significant degree the operating conditions of its burners.Translated from Ogneupory, No. 3, pp. 41–43, March, 1987.     

铁基载氧体辅助无烟煤焦富氧燃烧动力学分析

流化床铁基载氧体辅助富氧燃烧下传统石英砂床料被铁基载氧体替代,铁基载氧体扩展了传统床料的“热载体”的功能,另承担了“氧载体”的角色,为调节炉内氧分布与煤燃烧过程匹配提供了新思路。本文在热重实验平台探究了10%O₂/90%CO₂气氛下分析纯Fe₂O₃、赤铁矿及钢渣三种铁基载氧体辅助无烟煤焦燃烧特性及动力学。结果表明,相较于纯无烟煤焦燃烧,铁基载氧体辅助燃烧下无烟煤焦的燃烧特性得到显著改善,其中燃烧速率提高29%以上,燃尽温度降低65℃以上,综合燃烧指数提升2倍以上,活化能与指前因子同步增加且表现出“补偿效应”。三种铁基载氧体中分析纯Fe₂O₃对无烟煤焦燃烧特性的改善略优于赤铁矿和钢渣,钢渣可作为流化床铁基载氧体辅助富氧燃烧的床料替代石英砂。     

Heat of combustion of coal: Basic principles and new calculation methods

Stepwise changes in the heat of combustion of Donetsk Basin coal and vitrinites during metamorphism are implied by correlation analysis of a sample including data regarding the composition and properties of bed specimens. On the basis of the relative rates of oxidation processes with the liberation of oxygen-bearing gases and carbon accumulation, as well as the rate of subsequent carbon-ring formation, we note the difference in rate and direction of change in the heat of combustion within three successive intervals: 32–36, 36.3 ± 0.3, and 36–34 MJ/kg. The yield of volatiles may be employed as a predictive parameter in the regression equation for preliminary calculation of the heat of combustion with mean square deviation 0.325 MJ/kg.     

Determining the kinetic parameters of the reactions of propane dehydrogenation over a molybdenum catalyst by mathematical modeling

The process of propane dehydrogenation over a molybdenum catalyst is studied, and the kinetic constants of the chemical reactions are determined. The developed mathematical model made it possible to determine the limiting stage of the entire process, which is one of the industrial methods for producing propylene and hydrogen.     

Fluidized bed combustion of high ash anthracite: Analysis of combustion efficiency and particle size distribution

Fluidized bed combustion of high ash anthracite (HAA) was experimentally studied. The combustor consists of 0.25 m ID bed, and auxiliary equipments for coal feeding, ash removal, lemperature control, etc. Experimental results elucidate main cause of fuel loss to be elutriation of fines (i.e., flyash) containing unburned carbon. However, detailed balances of particle size distribution show majority of carbon in flyash comes from fines contained in the feed instead of attrition of coarse particles. The latter is the main source of flyash for conventional coal. The difference is due to much smaller attrition rate of HAA; feed HAA particles do not shrink much in size by combustion and attrition.     

基于铁基载氧体的无烟煤化学链燃烧过程中硫分布特性

在间歇式固定床反应器上,基于Fe₂O₃/Al₂O₃载氧体,研究了还原阶段反应温度和Fe₂O₃负载量对无烟煤化学链燃烧产物及S元素分布的影响。研究结果表明,含碳气体释放量随反应温度升高而增加,随Fe₂O₃负载量先增加后减少。产物中CO₂比例随反应温度升高先增加后减少,在850℃时达到最高（37.6%）。在实验条件下,未检测到SO₂生成。反应2 h时,载氧体中S元素的富集程度随温度和Fe₂O₃负载量升高而增加;5.5 h时,载氧体中S元素分布比例随温度升高而显著降低。利用SEM分析了载氧体表面微观形态结构。分析表明,Fe₂O₃负载量大于40%会导致载氧体轻微烧结。     

Enhancement of combustion efficiency with mixing ratio during fluidized bed combustion of anthracite and bituminous blended coal

In order to investigate the effect of mixing ratio of bituminous coal to blended coal on the enhancement of combustion efficiency, combustion experiments of blended coal with anthracite and bituminous are done in a laboratory scale fluidized bed combustor (10.8 cm ID and 170 cm height). The gross heating values of anthracite and bituminous coal used in this study are 2,810 cal/g and 6,572 cal/g, respectively. Experimental parameters are fuel feed rate, superficial gas velocity and mixing ratio of bituminous coal to blended coal. The combustion efficiency increases with the mixing ratio of bituminous coal due to the lower unburned carbon losses and higher burning velocity of bituminous coal. The rate of combustion in the combustor was increased with mixing ratio resulted from a higher burning velocity of bituminous coal. The measured combustion efficiency experimentally is about 3.5-12.4% higher than that of the calculated value based on the individual combustion of anthracite and bituminous coal under the same operating conditions. The optimum mixing ratio (MR) of bituminous coal determined is around 0.75 in this study. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.