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Under the condition of keeping the utilization of pulverized coal in BF, through relaxing the coal particle size properly to save power consumption, to lower flour milling costs and to improve coal mill production, the purpose of reducing ironmaking cost can be achieved. Size composition and combustion characteristic of pulverized coal injected into BF at Nansteel were analyzed under laboratory condition, and the feasibility of relaxing particle size was discussed. Industrial practice was carried out at Nansteel and the percentage of pulverized coal with its particle size less than 74??m was reduced from 73. 43% to 59. 47 %, meanwhile, the ratio of larger than 355??m was kept. Under the condition of keeping the BF production stability and anterograde and raw material and fuel unchanged, it can be found that before and after relaxing the coal practicle size, pulverized coal utilization basically keep the same. During bituminous coal and anthracite mixed blowing, the proportion of less than 74??m can be reduced, there is no need to control the proportion to 80%, then the production of coal mill will be increased, and energy consumption of pulverizing will also be decreased.     

KMnO4��ȼ��¯�紵ú�۵Ļ���

KMnO4 is a kind of pulverized coal combustion improver which is suited for the blast furnace. Mn7+(CO-)7 weakened bridge adhesion of carbon structural units and changed lattice structures, activation energy of pulverized coal was lowered and burn rate was accelerated. The unburned coal, which was investigated by the method of XRD and SEM, was collected through simulating combustion conditions of blast furnace. The results show that: microcrystalline parameters of unburned coal is increased, height and diameter of aromatic slices will increase 0??0013 and 0??0366nm respectively as KMnO4 joined; particles size of unburned coal powder can be reduced 2??62??m by adding KMnO4.     

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The coal- based direct reduction- magnetic separation was adopted to deal with the high phosphorus oolitic hematite after the mineral composition and structure of this ore were identified by XRD and SEM, and the factors which effected the process were studied and analyzed. The results show that the optimum process condition is temperature of 1250??, time of 30min, carbon/oxygen ratio of 1. 8 and basicity of 0. 8, under this condition , the magnetic concentrate yield is 47. 68%, concentrate grade is 86. 51%, recovery rate of iron is 92. 94%, phosphorus content is 0. 18% and metallization rate is 92. 56%, the recovery rate of phosphorus of tailing is 92. 88%.     

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The high- temperature pyrolysis of pulverized coal injection in blast furnace was simulated by arc plasma pyrolysis equipment. The pyrolysis solid- phase residue was analyzed by XRD and IR. The effect of MgO on coal pyrolysis rate and its combustion mechanism were investigated. The results show that the addition of MgO in the mixed coal can improve the thermal decomposition of coal. When the addition of MgO content is 8. 01mass%, the pyrolysis rate of pulverized coal reaches 62. 17% which increases by nearly 15% compared with the raw coal pyrolysis rate of 47. 51%. So the addition of MgO has obvious catalytic effect on the thermal decomposition of mixed pulverized coal. With the addition of MgO, the stacking height of aroma flakes and the condensation degree of aromatic carbocycles are improved. MgO can promote the decarburization reaction of pulverized coal to break the network of aromatic hydrocarbons??resulting in small molecular oxygen- containing groups to promote decomposition and combustion.     

催化剂对煤粉燃烧特性的影响及动力学研究

 采用热分析技术,研究了CaO、Fe2O3、MgO和MnO2 4种催化剂对精煤和瘦煤燃烧特性的影响,以及非等温燃烧条件下,催化剂对燃烧反应动力学参数的影响。研究表明：当加入量为1%时,4种催化剂都能降低精煤和瘦煤的初始燃烧温度,其中CaO对煤粉的催化助燃效果最为显著。同为过渡金属氧化物,当加入量小于2%时,MnO2降低两种煤粉初始燃烧温度的效果要好于Fe2O3;当加入量为2%时,MnO2降低两种煤粉初始燃烧温度的作用减弱,比Fe2O3的作用?睿尤胧菝菏匝保孟窒笥任飨浴?种催化剂都能降低精煤和瘦煤在第1反应阶段的活化能,其中CaO表现出的助燃效果最好;在第2反应阶段,CaO对精煤的催化燃烧作用最好,而4种催化剂对瘦煤的催化燃烧作用不明显。     

Combustion Property and Kinetic Modeling of Pulverized Coal Based on Non-isothermal Thermogravimetric Analysis

Non-isothermal combustion kinetics of two kinds of low volatile pulverized coals （HL coal and RU coal） were investigated by thermogravimetrie analysis. The results show that the combustibility of HL coal was better than that of RU coal, and with increasing heating rate, ignition and burnout characteristics of pulverized coal were improved. The volume model （VM）, the random pore model （RPM）, and the new model （NEWM） in which the whole combustion process is considered to be the overlapping process of volatile combustion and coal char combustion, were used to fit with the experimental data. The comparison of these three fitted results indicated that the combustion process of coal could be simulated by the NEWM with highest precision. When calculated by the NEWM, the activation energies of volatile combustion and coal char combustion are 130.5 and 95.7 kJ · mol^-1 for HL coal, respectively, while they are 114.5 and 147.6 kJ ·mol^-1 for RU coal, respectively.     

Mechanism of Effect of Microwave Modification on Pulverized Coal Combustion Properties

The mechanism of microwave modification on facilitating the combustion properties of pulverized coal(PC)was investigated.Experimental researches on granularity and functional group as well as combustion properties of PC before and after modification were carried out.Micromorphology observation indicated that the size of PC particles was relatively small,which was in accordance with the results of granularity analysis of PC.FT-IR(Fourier-transform infrared)spectra of two PCs indicated that the proportion of the functional groups with high activity increased after microwave irradiation.Furthermore,no valid effect of microwave was found on carbon matrix except small variations in PC particle size,which only led to subtle improvement in combustion of residual coke.Activation energies of Yungang and Yangquan PCs in temperature zone between 450-650℃ were reduced by 12.00%and 10.13%,respectively,which meant that microwave modification might effectively facilitate the combustion properties of PC.Nevertheless,decrease in activation energies of residual cokes was 3.56%and 3.67%respectively,which was subtle and can be regarded as the result of smaller particle size produced by microwave irradiation.     

煤粉富氧燃烧特性及动力学分析

 利用热分析法研究了富氧条件下高炉喷吹煤粉的燃烧特性。结果表明,富氧气氛可以改善煤粉燃烧特性,使煤粉着火点、失重峰提前,失重峰值增大,燃尽温度降低,综合燃烧特性指数明显提高,燃烧特性得到改善。当氧的体积分数小于40%时,煤粉燃烧特性改善幅度较大;氧的体积分数大于40%时,煤粉燃烧特性改善趋势变缓。同时采用非等温模型Flynn-Wall-Ozawa(FWO)对富氧之后煤粉燃烧过程进行动力学分析,当氧的体积分数由21%增加到100%,煤粉燃烧活化能从95. 15kJ·mol-1增加到169. 99kJ·mol-1。     

提高预热煤粉燃烧率的机制

 以邯郸钢铁公司2种高炉喷吹用煤粉作为原料,用马弗炉进行预热,测定不同温度预热后的失重率和燃烧率,并采用扫描电镜（SEM）观察预热后煤粉表面结构的变化。试验结果表明,烟煤150℃预热时的失重率为512%,且随着预热温度升高,煤粉的失重率增加,预热温度300℃时失重率可达到17.24%。无烟煤预热后失重率变化不大,预热温度为300℃时失重率仅为5.66%。预热后煤粉燃烧率明显升高。300℃预热条件下的烟煤燃烧率为89.74%,相对于原煤提高了15.67%,无烟煤燃烧率为85.19%,相对于原煤提高了24.80%。预热后煤粉表面结构发生了明显变化,层状和孔隙结构增加,从而提高了煤粉的燃烧率,为提高预热煤粉的燃烧率提供了理论基础。     

Investigation on Pulverized Coal Combustion Behavior by Non-Isothermic Integral Thermogravimetry Method

 The combustion process of pulverized coal was investigated by non-isothermic integral thermogravimetry. The thermogravimetry curves were fitted by the Coats-Redferm approximation function, and kinetic parameters and characteristic temperatures were obtained. The optimal mixing ratio and particle size can be ascertained. The characteristic temperature of pulverized coal can be obtained from the thermogravimetry curve, and the combustion of coal can be divided into homogeneous and heterogeneous combustion according to the differential thermal analysis curve. The activation energy of a single type of coal ranking from low to high is as follows: bituminous coal, meager-lean coal, and anthracite. In the first mixing method, with more low-price meager-lean coal B replacing high-price anthracite A, the activation energy slightly decreases; with more bituminous coal replacing meager-lean coal, total tendency makes a declining of activation. In the later mixing method, with an increase in particle size, a declining activation energy can be seen in total tendency.     

基于二维数值模拟的煤粉燃烧性能的研究

运用数值模拟的方法,建立燃烧炉内煤粉燃烧过程的二维数学模型,对两种混煤粉和新钢高炉现用喷吹煤粉在燃烧炉内的燃烧特性进行了模拟,分别得到了两种混煤及新钢高炉喷吹煤粉在燃烧炉内燃烧形成的温度场和焦炭分布规律。结果表明：两种混煤的燃烧性能明显好于新钢高炉喷吹煤粉。采用热重法测得3种煤的燃烧率和与CO2的反应性,得出了与模拟结...     

O_2/CO_2气氛下煤粉燃烧特性模拟研究

针对煤粉燃烧器燃烧工况,采用Fluent软件,探索辐射模型、气氛和煤粉粒径对煤粉燃烧过程的影响及污染物生成情况。结果表明:采用DO+WSGG模型时,煤粉的燃烧温度有所降低;跟空气气氛相比O_2/CO_2气氛下煤粉的燃烧温度降低,NO的量也降低;氧浓度增大,煤粉燃烧的温度峰值增加;随着超细煤粉混合比的增加,燃烧高温区而向前移。     

Gas-Particle Flow and Combustion Characteristics of Pulverized Coal Injection in Blast Furnace Raceway

The two-dimensional steady-state discrete phase mathematical model is developed to analyze gas-particle flow and combustion characteristics of coal particles,as well as components concentration and temperature distribution of coal gas in the process of pulverized coal injection of blast furnace raceway.The results show that a great deal of coal gas discharges on the top of raceway away from the tuyere,and the residence time of coal particles in the region of blowpipe and tuyere is 20 ms or so and 50 ms when it reaches raceway boundary.The pressure is the highest at the bottom of raceway and the maximal temperature is about 2423 K.The char combustion is mainly carried out in the raceway and the maximum of char burn-out rate attains 3×10-4 kg/s.     

高炉采用氧煤燃烧器后回旋区煤粉燃烧过程的数值模拟

针对高炉风口前回旋区内氧煤燃烧器喷入煤粉燃烧的过程，应用数值模拟方法对氧煤燃烧器在不同喷煤粉量和氧浓度条件下的燃烧过程进行了计算机数值模拟。结果表明，高炉风口产生的回旋区流场及温度场有利于煤粉的燃烧，而氧浓度大则有利于煤粉较早着火及较高的燃烬率。