淮钢—Praxair电弧炉二次燃烧技术

1　淮钢 Ｐｒａｘａｉｒ二次燃烧系统在电弧炉没有采用二次燃烧技术前 ,炉气中的ＣＯ数量约为 15 %～ 2 0 % ,其中约有 60 %～70 %未经炉内燃烧而直接进入除尘系统 ,并在除尘系统的水冷套管处同野风混合而燃烧。不但浪费能源 ,且给尘降室的使用和维护及除尘装置的温度控制带来难度。如何充分利用这部分能源 ,优化炉后废气 ,让ＣＯ尽可能在炉内燃烧生成ＣＯ2 ,并使反应生成的热量被传至炉料或溶池 ,是二次燃烧技术的关键[1] 。淮钢电弧炉实施的二次燃烧技术是由淮钢和美国Ｐｒａｘａｉｒ公司合作完成的。淮钢 Ｐｒａｘａｉｒ二次燃烧系统包…     

Pyrelance氧枪系统在50tUHP电弧炉上的应用

抚顺特殊钢公司于 1 992年从德国克虏伯公司引进 50ｔ超高功率电弧炉 (表 1、表 2 ) ,实现了一次热试成功。随着 1 998年大方坯连铸机投产(表 3 ) ,如何实现多炉连浇 ,提高钢水收得率 ,便成为研究的重要课题。现代电弧炉大都采用下列技术 :废钢预热 ;利用化学能 (二次燃烧技术 ) ;外加能源 ;氧燃烧嘴 ;偏心底出钢 ;碳氧喷枪 ;冶炼过程计算机自动控制 ;直接导电电极臂 ;长弧泡沫渣操作等[1,2 ] 。抚钢 50ｔＵＨＰ电弧炉 ,除氧燃烧嘴和碳氧喷枪技术外 ,其他技术都已采用。目前电弧炉冶炼时间约88ｍｉｎ ,连铸只实现三连浇。为实现多炉连浇 ,抚…     

电弧炉用废钢预热技术

为了提高电炉炼钢的生产率并降低其生产成本,已进行了大量有效的工艺和设备改善,如高功率化、大容量化富氧操作;采用氧燃烧咀和EBT(偏心炉底出钢)技术;进行炉外精炼及采用DC(直流)电弧炉等.而近几年,如何减少电炉排出的废热,特别是利用其高温废气预热废钢则成了重点.下面简介当今多种主要的废钢预热技术.     

电弧炉炼钢中碳氧二次燃烧的影响因素和应用

电弧炉炼钢时，废气与熔池和渣子接触，CO气体的温度接近钢水温度，整个过程基本由反应动力学条件控制，凭借吹氧可以在熔池上方进行二次燃烧。1台60t电弧炉2000多炉的二次燃烧的应用结果表明，当吹入氧气操作得当，二次燃烧对水冷炉壁、炉顶、电极寿命、3角区耐火材料寿命、金属烧损率均无影响，氧耗增加7．93m^3/t，电耗降低38kWh/t，冶炼周期可稳定缩短4min。     

K-ES工艺——降低电耗的高生产率电弧炉炼钢法

为有效地在电弧炉中使用化学能,进一步提高生产率和降低成本,Klockner Contrecting and Technologie公司(KCT)将OBM、K-OBM和KMS转炉技术的原理应用于电弧炉炼钢,采用了以下三种技术: (1)主要能量由煤或焦炭来提供,并吹氧以达到高效燃烧; (2)炉内采用二次燃烧技术,使释放的热量达到最大; (3)用炉底风嘴吹惰性气体或氧气来搅拌熔池,以加快熔清速度、改善金属/渣平衡和控制熔体中气体含量。     

Consteel电弧炉炼钢用碳氧枪水模型冷态试验和应用

通过冷态水模型试验 ,改进了西宁特钢引进的Consteel碳氧枪技术 ,确定了喷头倾角25° ,氧枪进入工作位后与炉底水平面保持 35°～ 50°夹角等技术参数。该项改进的技术改善了电弧炉内钢液温度场和流场 ,减少炉底和炉门局部侵蚀 ,加强钢水液面的旋转。应用结果表明 ,每只氧枪炼钢的炉数达到486炉 ,电弧炉炉壳寿命提高28炉 ,每炉钢冶炼时间缩短8 min。     

热风炉内氧—燃料燃烧——减少30%CO_2排放的基础

"无焰"氧—燃料燃烧是一项成形技术,已在钢包预热和加热炉上应用。在应用过程中发现,该项技术可以节省约50%的燃料,同时也可以减少CO2排放。将部分无焰氧—燃料燃烧原理应用到高炉热风炉是一种新的尝试。与传统燃烧方式相比,该技术可使操作成本大幅降低,这是源于其有效的废热回收,以及采用"热"的富氧烟气循环来替代"冷"空气。由于用二氧化碳替代了不辐射的氮分子,增强了炉内的热量传递。氧—燃料燃烧概念的一个重要推论就是烟道烟气中CO2的体积分数大约可提升40%~50%,且质量流量变为原来的两倍。该项技术容易实现低成本碳捕获,而且如果实现碳封存,那么就有可能减少整个炼钢流程中大约30%的碳足迹。     

中国大型电弧炉发展概况

介绍了中国近１０年大型电弧炉的建设概况,重点介绍直流电弧炉、新型废钢预热电弧炉以及氧燃烧嘴、二次燃烧等技术在国内的发展现状以及存在的问题。     

Consteel电炉二次燃烧控制技术

以宁夏电投钢铁有限公司引进Consteel电炉为例,结合Consteel电炉工艺特点以及废钢在电炉中熔化和精炼时发生的化学反应阐述了Consteel电炉二次燃烧原理。Consteel电炉二次燃烧控制系统由操作站和PLC柜组成。以Simatic S7-400 CPU414-2 DP控制器为核心,基于Profibus网络和工业以太网进行数据通信。PLC控制程序采用Simatic Step 7编写,实现了预热段首端二次燃烧调节挡板控制、主烟道调节挡板控制、动态密封风机速度控制等功能。监控软件采用SCADA软件,可以输入与二次燃烧控制有关的设定值并显示监控数据。实际应用表明Consteel电炉二次燃烧具有节能降耗优势。     

电弧炉操作的改进——用电子计算机系统控制

1.引言近代电弧炉炼钢技术,在各方面有所改进和发展,趋向于较大的电弧炉和超高功率、采用吹氧和预热烧嘴、炉外精炼和连铸、利用废气加热废钢的预热设备等等。在日本,许多工厂采用自动熔化控制系统、如大同钢铁公司在电弧炉上采用ARMS—Ⅰ控制系统来合理使用电能。目前,在这些控制系统中,尚有个别操作技术还有待建立。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.