本文關(guān)鍵詞：鐵氧化物富氫還原動(dòng)力學(xué)研究　出處：《北京科技大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 氫還原 鐵氧化物 結(jié)構(gòu)演變 燒結(jié)

【摘要】：隨著全球?qū)O：溫室氣體排放的限制越來(lái)越嚴(yán)格,冶金工作者們重新開始重視氫還原方面的研究。然而要實(shí)現(xiàn)氫還原在冶金中的實(shí)際應(yīng)用,需要進(jìn)一步全面了解氫還原的反應(yīng)特征和控制方法。目前為止,雖然鐵氧化物氫還原已有許多研究,但對(duì)某些特殊行為,如反應(yīng)速率隨溫度的升高異常下降仍沒有確切解釋。此外,高溫下產(chǎn)物易粘結(jié)、富氫還原低溫易析碳、還原氣體利用率低、廉價(jià)氫氣的大規(guī)模制備等問題仍然存在,需要人們?nèi)ソ鉀Q。本文從氫還原動(dòng)力學(xué)及產(chǎn)物結(jié)構(gòu)變化的角度,對(duì)上述部分問題加以研究,分析不同還原條件對(duì)其的影響。使用熱重分析法對(duì)Fe_2O_3粉體、Fe304粉體、FeO粉體和薄片狀FeO在等溫和非等溫條件下的靜態(tài)還原過程進(jìn)行了研究,考察了溫度、還原氣體成分、分壓、恒溫時(shí)間等因素對(duì)還原動(dòng)力學(xué)和反應(yīng)機(jī)理的影響。結(jié)合掃描電鏡和XRD檢測(cè),對(duì)不同還原條件下速率、還原分?jǐn)?shù)變化及產(chǎn)物燒結(jié)現(xiàn)象進(jìn)行了分析,主要結(jié)論如下。Fe_2O_3粉體和Fe304粉體在還原過程中均有反常溫度效應(yīng)出現(xiàn),反應(yīng)速率隨溫度升高而減小,速率異常變化與FeO→Fe階段的還原有關(guān)。Fe_2O_3粉體873K以上還原過程中Fe3O4→FeO與FeO→Fe是同步進(jìn)行的。純氫中出現(xiàn)少量CO可使速率發(fā)生較大下降。溫度低于1173K的保溫過程不影響還原前后的反應(yīng)速率和產(chǎn)物燒結(jié),燒結(jié)只發(fā)生在還原過程中。FeO粉體在933-1073K還原過程中現(xiàn)了反常的溫度效應(yīng),產(chǎn)物燒結(jié)和致密化現(xiàn)象是主要原因。H_2-Ar等溫還原研究表明,在973 K-1023 K,氫氣含量的增加使得最終還原度降低。產(chǎn)物結(jié)構(gòu)分析顯示,氫氣含量增加使得新生鐵相粘結(jié)加劇,阻礙反應(yīng)氣擴(kuò)散。H_2-CO等溫還原研究表明,873K和973K還原中存在明顯的析碳反應(yīng)。873K,30%H_2+70%CO條件下最易發(fā)生析碳反應(yīng),高溫還原可有效避免其發(fā)生。
[Abstract]:With the global CO: to limit greenhouse gas emissions more and more strict, the metallurgy workers begin to attach importance to the hydrogen reduction of the hydrogen reduction. However in order to realize the practical application in metallurgy, the need for further comprehensive understanding of reaction characteristics and control methods of hydrogen reduction. So far, although there have been many studies on reduction of iron oxide, but for some special behavior, such as the reaction rate increases with the increase of temperature anomaly decline still did not explain exactly. In addition, the product is easily under high temperature bonding, hydrogen rich reducing carbon reduction gas at low temperature, low utilization rate, large cheap hydrogen gas production still exists, need to be solved. In this paper, angle reduction kinetics and product the structure changes from hydrogen, to study on the part of the problem, analysis of the influence of different conditions on the reduction. Using the thermogravimetric analysis of Fe_2O_3 powder, Fe304 powder, FeO powder and Slice FeO in static conditions under isothermal and non isothermal reduction process was studied, the effects of temperature, reducing gas composition, pressure, temperature and other factors on the impact of time reduction kinetics and reaction mechanism. Combined with scanning electron microscopy and XRD assay of different reduction conditions rate, reducing fraction and product sintering phenomenon has carried on the analysis, the main conclusions are as follows.Fe_2O_3 powder and Fe304 powder were in the reduction process of abnormal temperature effect, the reaction rate decreases with the increase of the temperature, the above reduction of.Fe_2O_3 powder 873K and FeO, Fe abnormal rate of change stage of the reduction process of Fe3O4, FeO and FeO, Fe is synchronized with the pure. In a small amount of CO can make the hydrogen rate greatly decreased. The temperature is lower than the thermal process of 1173K does not affect the reaction rate and product reduction before and after sintering, the sintering occurs only in the reduction process of.FeO powder in 9 In the process of the 33-1073K reduction effect of temperature anomalous, product sintering and densification phenomenon is the main reason of.H_2-Ar isothermal reduction studies show that in 973 K-1023 K, increasing the hydrogen content of the final reduction degree decreased. The analysis shows that the product structure, increase the content of hydrogen bond makes the new iron phase intensifies, hinder the reaction gas diffusion.H_2-CO isothermal reduction research show that 873K and 973K have obvious reduction of carbon precipitation reaction of.873K, the most prone to carbon deposition reaction under 30%H_2+70%CO conditions, high temperature reduction can be effectively avoided.

【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TF511

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 楊兆祥;段振瀛;;含氟高爐型爐渣中堿金屬還原動(dòng)力學(xué)的研究[J];鋼鐵;1981年09期

2 鄭修貴;;鐵礦石流態(tài)化氣體還原動(dòng)力學(xué)參數(shù)計(jì)算[J];化工冶金;1980年01期

3 劉^，

本文編號(hào)：1367746