钢水脱气用真空泵系统的选择

干式机械真空泵(MVP)在钢水脱气工艺中的应用在过去10年间取得了巨大进展,但主要局限在炉容小于150t;推广到更大炉容的工作正在进行中。因为有蒸汽来源,蒸汽喷射真空泵(SVP)主要用于联合钢厂150～350t的大炉容。除了投资和运行成本方面的考虑,所有真空工艺和设备类型都能够不受限制地使用任何类型的现代真空泵系统。这2种系统都能够满足全部的冶金要求。由于MVP系统的运行成本明显降低,所以有必要重新审视在减少漏气、使用保护气体和降低泵组与冶金反应罐间压力损失等方面的努力。这2种系统的能效都得到了提高,但MVP的能源优势更为明显。在对真空泵系统进行比较时,应当只考虑总成本,包括为满足排放限制和安全标准的要求而必须付出的成本以及反应罐内的压力。此外,还应当重新考虑除尘系统的类型和使用,因为它们能够通过减少清理次数、节省用水、减少淤泥处理、降低SVP系统的设计抽气能力来显著降低成本。在同基于体积流量的MVP比较前,需要利用一个特殊的系数对SVP的质量流进行修正。根据所选泵需要的工作压力,MVP系统能够以明显低于SVP系统的质量流在反应罐达到同样的性能。     

钢水真空脱气处理的成本结构

 在很宽的钢水质量范围内对包括钢包炉和多种真空处理在内的二次冶金工艺的成本进行了分析,并对两种常用的真空泵系统进行了比较。干式机械真空泵在最多360t的整个钢水质量范围内都具有明显的成本优势,节约的幅度随工艺而变化,具体同能源(无论何种形式)的供应和设备的产能有关。通过快速抽真空缩短处理的周期时间,降低了钢水的过热需要,从而降低了生产成本,提高了产能,改善了质量。     

Change of Inclusion Characteristics during Vacuum Degassing of Tool Steel

The inclusion characteristics were studied during vacuum degassing by interrupting the operation at five different times after the start of operation. Slag and steel samples were collected and thereafter assessed with respect to steel and slag composition, total oxygen content, size distribution of inclusions and chemical composition of inclusions. The main conclusion is that the number of inclusions in the different size classes as well as the total oxygen content seem to reach a minimum value after around ten minutes of vacuum degassing. Furthermore, it seems to be a consistent trend that, during vacuum degassing, the top slag influences the inclusion composition.     

薄板厂210t RH脱气工艺研究

通过在薄板厂宽厚板铸机生产钢种的工业性试验,得出:在RH真空度不大于0.27 kPa,环吹氩流量在1 200～1 500 L/min范围,高真空时间在10 min以后,钢中w[H]可以达到2×10-6以下,而且在高真空时间为16 min时,钢中w[H]、w[O]和w[N]平均分别为1.6×10-6、13.2×10-6和41×10-6。     

Effect of Top Slag Composition on Inclusion Characteristics during Vacuum Degassing of Tool Steel

The focus of the study was to investigate the effect of the chemical composition of the top slag on the inclusion chemical composition during vacuum treatment of a plastic mould tool steel. Sampling was done before and after vacuum degassing. The chemical composition of the inclusions was determined by using SEM combined with EDX. The results showed that several inclusion compositions were found before vacuum degassing, while only one main composition of inclusions was present after vacuum degassing. Furthermore, the composition of the top slag was found to have a great influence on the composition of the inclusions found in samples taken after vacuum degassing. The present study also shows that the vacuum degassing effectively reduces the number of inclusions in steel. Finally, the thermodynamic calculations of the activities using Wagner's equation were found to predict a lower oxygen activity value than the calculations made using the Thermo‐Calc software.     

炼钢真空脱气系统泄漏的控制

阐述了炼钢真空脱气系统由于联接环节多,工作环境恶劣等种种原因导致泄漏激境,并指出应从设计、制造、安装调试和投产使用各个环节控制和减少泄漏的产生。     

真空脱气对粉末冶金Ti2AlNb合金力学性能的影响

采用无坩埚感应熔炼超声气体雾化法制备了成分为Ti-22Al-24Nb-0. 5Mo(原子分数,x/%)的预合金粉末,并对预合金粉末的化学成分、表面状态及流动性等进行了表征。通过包套热等静压工艺制备了粉末冶金Ti2AlNb合金,研究了真空脱气对粉末冶金Ti2AlNb合金力学性能的影响。结果表明,超声气体雾化法制备的Ti2AlNb合金粉末化学成分批次稳定性好;从粉末填充的工艺性能方面考虑,热等静压成形应选取粒度小于250μm以下的全粒度分布预合金粉末;真空脱气处理可减少粉末冶金Ti2AlNb合金的孔隙缺陷,提升合金拉伸性能的稳定性和高温持久寿命。     

VD真空精炼技术与装备的发展现状

介绍了VD真空精炼技术的发展现状,指出VD功能多元化应是今后发展的主要趋势,提出重点研究开发氧脱碳（碳脱氧）、深脱硫、深脱气技术是实现VD功能多元化的关键。在此基础上,介绍了高效化生产装备和干式机械泵系统应用于VD真空精炼的情况,指出干式机械泵系统应用于真空精炼是一种可行的选择。     

环流式真空脱气装置的钢水混合与循环

通过实测数据及理论参数建立了ＲＨ环流和主要影响因素间的应用关系,计算结果与工业试验数据相吻合。定量分析了顶吹方法对ＲＨ环流过程钢包所获得的单位搅拌功率的影响。结果表明,顶吹氧射流对钢包混匀时间和循环流量的作用可以忽略。