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。     

高炉内煤粉燃烧速度场的数值模拟

文章利用商业软件FLUENT,采用有限体积法建立了高炉内回旋区煤粉燃烧三维数学模型。在不同煤比和不同富氧率下,分析研究了煤粉燃烧过程的速度场、颗粒轨迹。模拟结果表明:采用动量方程、标准双方程湍流模型、离散相模型对高炉回旋区煤粉运动过程进行数值模拟,结果是合理的、可信的。喷煤量对煤粉颗粒运动过程气体的运动速度影响比较明显,对漩涡内的气体速度影响不是很明显。煤粉颗粒运动过程气体的运动速度随着富氧率的增加而有所增加,卷入漩涡的煤粉颗粒并不是随着富氧率的增加而增加。只有卷入漩涡的颗粒越多,越有利于煤粉的燃烧。富氧率对煤粉燃烧过程的有利影响随着富氧率的增加出现拐点,表明富氧率应该维持在一个合适的水平,并不是越高越好。     

An Improved Model for Char Combustion in Blast Furnace Pulverized Coal Injection

An improved char combustion model has been presented, taking additional consideration of the influence of the finite‐rate heterogeneous reduction and oxidation. Explicit algebraic expressions for the overall rate of combustion, the surface temperature of the particle, and the gas temperature at the flame sheet are given in the model. The transition between various limiting combustion conditions was analysed using the improved model. A Fourier Transform Infrared spectroscopy (FTIR) system was established to measure the particle temperatures. Rational agreement was achieved between the predictions and the data from the present work and the literatures. Compared with the single‐film model, the predictions of particle temperature by the improved model were in much better agreement with those predicted by the rigid continuous‐film model, while the calculation time for the improved model is 100,000 times faster than that using the continuous‐film model. It is shown that the present model could not only be integrated easily into comprehensive computing codes for industrial pulverized coal flame, but also considers most of the physico‐chemical processes involved and is then accurate enough for engineering applications.     

煤粉预热喷吹技术在高炉喷吹工艺中的应用

煤粉预热喷吹有利于减轻喷煤对热风的冷却效应、加速煤粉的燃烧过程而提高煤粉利用率。通过对潞安煤制成的喷吹煤粉样在不同预热温度下燃烧率测定,研究煤粉预热对其燃烧性影响规律。预热可以提高煤粉的燃烧率,并且随着预热温度的提高燃烧率不断升高。钢厂采用热风炉废烟气的余热,对高炉喷吹煤粉进行预热到150～200 ℃后喷吹,吨铁可以提高喷煤量10 kg,明显降低焦比和燃料比,有显著的经济效益和社会效益。     

Cold Model of Coal Gas Component Concentration Distribution in Blast Furnace Raceway

Primary distribution of coal gas in blast furnace raceway has an important effect on blast furnace ironmak-ing process. The coal gas component concentration distribution was studied experimentally using a three-dimensional cold model. The results showed that CH_4 concentration diminishes along with the height increasing on vertical sec-tion of raceway, and the concentration is the highest in the bottom of raceway. CH_4 concentration increases gradually along the raceway depth with the lowest concentration value in front of the tuyere. The distribution of CH_4 concen-tration has different characteristics in different raceway zones.     

Pulverized Coal Combustion of Nitrogen Free Blast Furnace

 The efficiency of coal combustion is an important factor for the blast furnace process. The influence of low xO/xC on coal combustion performance under nitrogen free blast furnace condition was researched through the self-developed pulverized coal burning device. The results show that the coal combustion rate reduces with xO/xC decreasing, and the combustion rate of bituminous coal is higher than that of anthracite. The coal combustion rate ascends with the rise of volatile matter, but when volatile matter of pulverized coal is more than 18%, the combustion rates will not increase correspondingly. Small amount of CaCO3 and CO2 additions can promote coal combustion, and the effect of CaCO3 is more apparent, which can increase the pulverized coal combustion rate by 15%-18% or so.     

Cold Model Study of Coal Gas Component Concentration Distribution in Blast Furnace Raceway

 Primary distribution of coal gas in blast furnace raceway has an important effect on combustion of coke and pulverized coal injection, as well as whole ironmaking process. According to practical production parameters of No. 5 blast furnace in Chongqing iron &; steel Co. LTD, the theoretical calculation model recommended by Nomura is adopted to determine penetration depth, height and width of raceway. Three-dimensional cold model of blast furnace raceway is established. Coal gas component concentration distribution of vertical section and cross section in blast furnace raceway is simulated using natural gas.     

Numerical Analysis of Pulverized Coal Combustion inside Tuyere and Raceway

The process of pulverized coal combustion inside the tuyere and raceway plays a very important role in the performance of a blast furnace. A three‐dimensional multiphase CFD model using Eulerian approach has been developed to simulate the coal devolatilization and combustion process inside tuyere and raceway. The velocity field, temperature distribution, and combustion characteristics have been determined in details and the effect of tuyere diameter on the pulverized coal combustion process has been predicted. Numerical results show that the pulverized coal combustion process displays different characteristics when the tuyere diameter changes. For a bigger diameter tuyere, there is more coal devolatilization, and combustion occurs inside the tuyere, which results in a better combustion condition compared to smaller tuyere diameters. The gas temperature distributions inside the raceway are dependent on the tuyure diameter; the temperature for the large size tuyere is higher than that of the small one. The coal burnout changes from 85.3% to 60.0% when the tuyere diameter reduces from 0.165m to 0.146 m.     

高炉喷吹用煤粉的燃烧性能研究

利用自制的燃烧试验装置研究了高炉喷吹煤粉成分和粒度对燃烧性能的影响,结果表明: 煤粉的成分对燃烧性具有较大影响,灰分升高燃尽性变差,挥发分升高燃尽性变好;煤粉的粒度对燃烧性也具有很大影响,粒度越小,燃烧速度越快,虽然粒度＜0071 mm的煤粉燃尽时间最短,但与0071~010 mm 和010~020 mm粒度级别之间的差别并不是很大,粒度＞020 mm时燃尽时间明显延长,020 mm是明显的分界点。     

梅山2号高炉大喷吹实践

梅山2号高炉开炉后通过采取提高原燃料质量,优化高炉操作,提高风温,选择合适的鼓风动能和富氧率等措施,控制煤气流合理分布,使高炉喷煤量达到150kg/t。     

煤粉在直吹管内燃烧行为的数值模拟

 建立了直吹管内气固流动、传热和煤粉燃烧的数学模型,基于实际高炉工艺参数,借助商业软件通过数值模拟的方法研究了直吹管内的气体成分和温度变化,并重点考察了煤粉粒径、鼓风含氧量和鼓风温度等操作参数对煤粉燃尽率的影响。研究结果表明：减小粒径、增加含氧量、提高鼓风温度都可以使煤粉在直吹管内的燃尽率得到提高。煤粉在直吹管内的燃烧行为以挥发分的脱除为主,该过程对温度敏感,而对氧气浓度不敏感。这一结论与前人在回旋区内得到的模拟结果相反。因此在研究变量对喷吹煤粉燃尽率的影响时,模拟区域应同时包含直吹管和回旋区。     

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...     

基于机器视觉的风口回旋区温度检测算法

 应用机器视觉理论，引用微元积分思想建立了辐射图像信息与高炉风口回旋区二维温度场梯度分布的关系模型，并针对CCD非接触测量回旋区温度过程中因温度过高易出现CCD输出过饱和电流问题，提出了大于CCD噪声总量和防止饱和电流输出的快门时间控制模型。通过小型煤气燃烧实验和高炉风口现场实验表明：该温度检测算法正确，快门控制模型能有效地防止图像出现“白炽”现象，提高了温度测量峰值。     

喷吹煤Y在首钢高炉的应用

通过对Y煤的基础性能研究,完成了其用于首钢高炉的可行性评价。与首钢现用A煤相比,Y煤的灰分接近、发热值高、理论置换比高、挥发分略低、硫分略高、可磨性指数相同一致、燃烧性略高。分析认为,Y煤使用后有利于降低燃料比。2009年9月在首钢炼铁厂某高炉进行配喷Y煤的工业试验,Y煤最高配比为35%,试验期间高炉顺行状况良好,校正置换比由0.80升高至0.83,高炉煤粉利用率较高,达到99%以上,并取得了良好的经济效益。     

O2/CO2气氛下煤粉燃烧数值模拟

采用CFD技术对不同气氛下煤粉燃烧过程进行了研究。用Fluent软件模拟不同工况下煤粉燃烧,获得煤粉燃烧的一些基础性参数,为实际应用提供相应的指导;建立包括气相湍流流动、气固之间传热、煤挥发分析以及燃烧等过程在内的三维数学模型;将不同气氛下煤粉燃烧的特性进行对比,研究气氛变化对燃烧的影响规律。     

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。     

我国高炉喷煤技术的发展

论述了我国高炉喷吹煤粉技术的发展过程,分析了提高高炉喷煤比的措施,通过提高焦炭质量、改善鼓风质量、采用氧煤喷吹、混合喷吹等技术和工艺措施可有效提高喷煤比。同时指出,研究回旋区条件下煤粉的燃烧过程,开发高效喷煤助燃剂,最大限度地提高煤粉在风口区域的燃烧率和喷煤置换比,是当前喷煤技术攻关的课题。     

高炉喷煤新技术--两段式喷吹工艺

通过二维冷态模型模拟了各种高炉操作条件对炉内积粉分布和料柱压差变化的影响。为了有效降低料柱压差，提高喷煤量，提出两段式喷吹煤粉新工艺，针对该工艺从理论上加以论证，并且通过冷态模拟试验进行验证。结果表明，两段式的喷吹方法有利于煤粉均匀分布，减缓了由于喷煤造成的空隙度下降，减轻了局部过量积娄，降低了高炉全压差，是一种有效地提高粉煤喷吹量的新技术。     

莱钢高炉喷吹煤粉利用率研究

测定了不同高炉炉尘中碳含量及矿物组成,分析了不同煤比对高炉炉尘中碳质量分数和未消耗煤粉比例的影响,确定了莱钢4座高炉在不同喷煤比时高炉炉尘中未消耗煤粉量、焦炭量和煤粉在高炉内的利用率。结果表明,取样高炉炉尘(重力灰和布袋灰)中1#炉碳含量最高,都在50%左右;2#高炉重力灰和布袋灰中最低,含量在分别在20%~30%和10%~15%;炉尘中未消耗焦炭以镶嵌结构为主,布袋灰中未消耗焦炭与煤粉面积比例远低于炉尘;高炉喷吹煤粉利用率达到98.17%以上。随着喷煤比增加,高炉吨铁炉尘量、未消耗碳呈现增加的趋势。高炉操作应根据原料条件合理控制喷吹煤比,降低炉尘碳含量。