A simulation study of reduction kinetics for sponge iron production in a rotary hearth furnace

ABSTRACT

A mathematical model has been developed by coupling genetic algorithm (GA) with heat and material balance equations to estimate rate parameters and solid-phase evolution related to the reduction of iron ore-coal composite pellets in a multi-layer bed Rotary hearth Furnace (RHF). The present process involves treating iron ore-coal composite pellets in a crucible over the hearth in RHF. The various solid phases evolved at the end of the process are estimated experimentally, and are used in conjunction with the model to estimate rate parameters. The predicted apparent activation energy for the wustite reduction step is found to be lower than those of the reduction of higher oxides. The thermal efficiency is found to decrease significantly with an increase in the carbon content of the pellet. Thermal efficiency was also found to increase mildly up to three layers. Multilayer bed remains as a potential design parameter to increase thermal efficiency.     

浅谈无缝钢管的壁厚偏差

通过探讨、分析无缝钢管壁厚偏差产生的原因，提出了改善钢管壁厚偏差的一些措施，并结合实际生产，得出了比较满意的结果。     

New rotary valves for pulse-tube refrigerators

In most used rotary valves in GM-type pulse-tube refrigerators the rotor makes heavy mechanical contact with the stator, so the valve is liable to wear, and large torques are needed. In this paper we will describe two types of valves, which have balanced forces on the rotor. In the first valve the rotor and the stator make no mechanical contact. The second type is a contact valve, like the classical valves, but the forces on the rotor are balanced in a different way. Therefore, these valves are less liable to wear, and the torques needed to rotate the valves are small.     

高温对冶金窑窑体的影响

针对冶金回转窑窑体在高温下产生的失效进行数值分析，并在此基础上对冶金窑窑体的设计方法进行修正。     

MICROSTRUCTURE AND FATIGUE PROPERTIES OF A WELDED DUPLEX STAINLESS STEEL

Abstract— In response to the increasing structural applications in duplex steels for welded structures, fatigue behaviour of a SAF 2304 grade duplex stainless steel was investigated, considering both the base metal and GTAW welded joints. Fatigue curves and fatigue limits under rotary bending fatigue were obtained. The study focused attention on the microstructural features of fatigue crack propagation of the two series of experiments, thereby permitting an evaluation of the tortuous crack path of welded joints and the mechanisms related to threshold microstructural barriers.     

VILOFT织物的染整工艺

新型VILOFT粘胶纤维织物具有独特的扁平截面，导湿透气，蓬松保暖。本文探讨该纤维织物的前处理，染色，整理工艺，优化并给出了具体工艺参数，对实际生产有一定的参考价值。     

Design improvements on rotary valve particle feeders used for obtaining suspended airflows

The back repulsion of low density particles, sticking of particles in feeder valve and interlocking and cohesive archs of particles in feeder hopper have been widely observed problems of a conventional rotary valve feeder used for feeding of granular particles into an airflow line. In this study, these problems of the rotary valve feeders were isolated by means of novel modifications to its conventional design. Results of the modifications showed that the modified feeder can be sensitively used to feed granular particles with mass feeding rates ranging between 5±0.15 and 85±0.85 g/s without encountering problems experienced with conventional rotary valves.     

环形转底炉海绵铁生产方法

介绍了国内外环形转炉生产海绵铁方法（Ｆａｓｔｍｅｔ法，Ｉｎｍｅｔｃｏ法和ＣＯＦ－Ｒ）发展状况。分析了此种工艺的工艺特点和热工特点，指出了这种方法与回转窑法，遂道窑法比较具有强大的市场竞争力。     

Ultrasonic-assisted drilling of Inconel 738-LC

Generally in the drilling of modern aviation materials such as nickel and titanium base super alloys, problems frequently occur in terms of burr formation at the cutter exit, tool stress, high heat generation on tool surface as well as low process reliability. A recent and promising method to overcome these technological constraints is the use of ultrasonic assistance, where high-frequency and low-amplitude vibrations are superimposed on the movement of cutting tools. This paper presents the design of an ultrasonically vibrated tool holder and the experimental investigation of ultrasonically assisted drilling of Inconel 738-LC. The circularity, cylindricity, surface roughness and hole oversize of the ultrasonically and conventionally drilled workpieces were measured and compared. The obtained results show that the application of ultrasonic vibration can improve the hole quality considerably. Improvements of up to 60% have been achieved.     

Accu—Roll轧管机组主减速机输出轴联轴器大过盈量装配

介绍了采用油温加热装配工艺,实现Accu-Roll轧管机组主减速机输出轴联轴器大过盈量装配。