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氧化铝回转窑熟料烧结过程影响参数研究 总被引:2,自引:2,他引:0
易正明 《有色金属(冶炼部分)》2011,(11):34-37
在对氧化铝熟料烧结过程进行分析的基础上,结合煤粉燃烧、物料热解、窑壁散热和窑内传热传质方程,建立了回转窑熟料烧结传热综合数学模型。在此基础上,利用现场实际参数,应用数值计算方法对模型进行计算求解,得到了氧化铝回转窑内气体和物料的轴向温度分布,并分析了熟料烧结过程中空气消耗系数和掺煤量等主要参数对窑内温度分布的影响,提出了相应的操作参数,为实现回转窑的操作优化和自动控制提供了可靠的依据,有利于实现回转窑生产的节能降耗。 相似文献
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在分析氧化铝回转窑传热过程的基础上,运用多相流理论对回转窑内横截面物料流动与传热过程进行数值模拟,研究了不同工况下横截面上的温度分布及流动情况。结果表明,截面上物料温度主要受气体及窑壁传热影响,物料颗粒越小,其内部温度上升越快,流动带起的物料高度也越低,但截面上物料内部温度分布基本趋于一致,并可忽略截面温差。 相似文献
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为了直观地得到某预热窑内烟气、物料的温度分布和气体流动状态,从而调整实际生产中预热窑的进气量、入口烟气速度及烟气出口压力等参数,采用数值模拟的方法建立了工业尺度的矿热炉炉顶预热窑三维模型,并用多孔介质模型和双温度方程研究窑内的温度场变化.研究结果表明:高温气体穿过进气梁上的进气孔时最大速度为45.27 m/s,与实测值44.6 m/s相差1.51%;气体入口附近形成近椭圆形的高温区域,出口附近的气体温度低于400 K,气体的热量利用率高;预热15,30,60 min时固体物料的最高温度分别为585.13,697.09,765.08 K;预热60 min时,预热窑底部出口的物料温度范围为524.8~762.29 K,实际生产中预热窑出口处物料最高温度在450~550℃范围内,符合预热窑实际工况. 相似文献
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在对钒钛磁铁矿焙烧回转窑的传热过程及物料运动行为进行研究的基础上,建立了钒钛磁铁矿焙烧回转窑温度分布数学模型。并应用数值计算方法对该模型进行求解,得到了中试回转窑内物料和烟气沿轴向的温度分布。结果表明:物料在刚进入回转窑时被迅速加热,随后升温速率减慢;当烟气温度较低时,对流换热系数为20 W/(m·K)左右,为辐射换热2倍;随着烟气温度升高,辐射换热成为主要机制,在窑尾处可达对流换热10倍左右;对于中试回转窑,数值计算模型与实验结果误差最高为50 K,具有较高的准确性,可指导生产中回转窑设备的优化。 相似文献
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Fabrice Patisson Etienne Lebas François Hanrot Denis Ablitzer Jean-Leon Houzelot 《Metallurgical and Materials Transactions B》2000,31(2):391-402
In order to simulate coal pyrolysis in a rotary kiln in the steady-state regime, a mathematical model has been developed which
calculates the temperature profiles in the charge, the gas, and the furnace walls, together with the gas composition and the
degree of removal of volatile species. The model takes into account the principal physicochemical and thermal phenomena involved,
including the complex movements of the charge; the gas flow; heat transfer between the charge, the gas phase, and the furnace
walls; drying and pyrolysis of the coal; the cracking of tars; the combustion of volatile species; and the combustion and
extinction of the coke. The data necessary for the model were obtained by specific experiments or from the literature. The
model has been validated by comparing its predictions to measurements performed on an industrial rotary kiln. The model has
been used to study the influence of operating parameters such as the furnace rotation speed, in order to optimize the process.
It is shown how a modification to the extinction zone leads to an increase in coke yield of 0.75 pct. 相似文献
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Based on conduction, convection and radiation heat transfer among the flue gas, kiln wall, and the pellet bed material, and on the basis of the coal combustion and analysis of reaction heat of pellet induration in the rotary kiln, the temperature field model of rotary kiln was established. Using visual studio net, matlab and open source computer vision library as development tools, combining with the ActiveX data objects database technology, the temperature field simulation system for rotary kiln of iron ore oxidized pellet production was developed. Temperature distribution of pellet and flue gas in rotary kiln was dynamically displayed. 相似文献
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回转窑预还原-氧煤燃烧熔分炼铁工艺直接使用宽粒级的粉矿入炉,炉料颗粒经回转窑内煤气逆流换热和预还原后,通过沉降管到达氧煤燃烧熔分炉。为避免沉降区域内炉料颗粒冲刷炉壁、壁面堆积及气固传热不均现象,实现颗粒沉降与传热过程的耦合控制,最大限度降低炉料与熔池温度差,保证熔池熔炼稳定,达到良好的冶炼效果,利用计算流体力学-离散单元法(CFD-DEM)研究氧煤燃烧熔分炉熔池上部区域煤气流速和炉料粒径对炉料颗粒在逆流煤气作用下的沉降轨迹与传热行为的影响。数值模拟结果表明,随着煤气流速增大,炉料颗粒的沉降速度减小,煤气对小粒径炉料颗粒的作用尤为明显。煤气流速为1 m/s时,每种粒径的炉料颗粒沉降效果良好;煤气流速为2 m/s时,粒径为1.0、1.5、2.0 mm的炉料颗粒沉降效果相对较好;煤气流速为3 m/s时,粒径为1.5、2.0 mm的炉料颗粒能够顺利沉降。针对炉料颗粒传热行为,煤气流速越大,炉料粒径越小,则炉料颗粒的传热效果越好。综合炉料传热与沉降行为,粒径为1.0 mm左右的炉料颗粒在煤气流速为1和2 m/s作用下,炉料颗粒的沉降速度和传热情况均良好。 相似文献
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《钢铁冶炼》2013,40(5):348-354
AbstractThe influence of post-combustion, heat transfer efficiency, and the degree of metallisation is studied with regard to coal saving and export gas in the COREX process using a thermochemical model. An increase in post-combustion ratio decreases the coal rate and the amount of reduction gas, which influences the achievable degree of metallisation, when no additional reduction gas is added to the system. Further post-combustion with oxygen generates a higher temperature than that with air at all post-combustion ratios. A higher heat transfer rate is necessary to keep the temperature of the gas within the refractoriness limits of the lining material. It is asserted that the post-combustion ratio, the degree of metallisation, and the medium for post-combustion must be adjusted according to the refractoriness of the lining material of the melter–gasifier, the efficiency of heat transfer mechanisms from the post-combustion zone to the bath, the gas handling efficiency, and the thermal energy requirement of the surplus gas, when considering the use of post-combustion in the COREX process. 相似文献
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Regenerative heat transfer in rotary kilns 总被引:6,自引:0,他引:6
J. P. Gorog T. N. Adams J. K. Brimacombe 《Metallurgical and Materials Transactions B》1982,13(2):153-163
A mathematical model has been developed to determine the temperature distribution in the wall of a rotary kiln. The model,
which incorporates a detailed formulation of the radiative and convective heat-transfer coefficients in a kiln, has been employed
to examine the effect of different kiln variables on both the regenerative and the overall heat transfer to the solids. The
variables include rotational speed, pct loading, temperature of gas and solids, emissivity of wall and solids, convective
heattransfer coefficients at the exposed and covered wall, and thermal diffusivity of the wall. The model shows that the regenerative
heat flow is most important in the cold end of a rotary kiln, but that generally the temperature distribution and heat flows
are largely independent of these variables. Owing to this insensitivity it has been possible to simplify the model with the
aid of a resistive analog. Calculations are presented indicating that both the shell loss and total heat flow to the bed may
be estimated to within 5 pct using this simplified model. 相似文献
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Fabrice Patisson Etienne Lebas François Hanrot Denis Ablitzer Jean-Leon Houzelot 《Metallurgical and Materials Transactions B》2000,31(2):381-390
A mathematical model is presented which describes the pyrolysis of a single grain of coal and is designed to be incorporated
into an overall model simulating the rotary kiln coal pyrolysis process. The grain model takes into account the principal
physical phenomena occurring during the conversion of coal to coke, namely, heat transfer toward and within the grain, drying
of the coal, and the evolution of volatile species. Particular care has been taken in the determination of the thermophysical
and kinetic parameters necessary for the model. Thus, the drying kinetics for Lorraine coal were measured by thermogravimetry.
The kinetics of pyrolysis were determined by both thermogravimetry and gasphase chromatography, in order to separately monitor
the evolution of the nine gaseous species considered. The true specific heat and the thermal conductivity of the solid were
also measured as a function of temperature. The numerical model, based on the finite-volume method, calculates the temperature,
composition, and mass flow rates for the different gases evolved at each point in the grain at any instant of time. The model
was, finally, validated by comparing the calculated and measured values of the overall conversion of the pyrolysis reaction
and the temperature at the center of the grain. 相似文献
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分析了山铝煤粉制备工艺流程中存在的问题,利用熟料窑窑头余热代替燃烧炉作为烘干煤粉的热源,对原工艺流程进行优化.以较少投入获得良好经济和环保效益,并对新工艺流程进行了阐述. 相似文献