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Study of Formcoke with Shenfu Char as Raw Material

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Tutor: GongZhiJian
School: Shandong University of Science and Technology
Course: Chemical processes
Keywords: Char,Formcoke,Binders,Coke oven
CLC: TQ522.1
Type: Master's thesis
Year:  2011
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Abstract:
The coal resource in our country is rich, but is distributed unenvenly, especially for the coking coal which can be used for coking. In order to ensure high coke quality,50% high quality coke coal must be added. Owing to small particle size, the char produced in the pyrolysis of Shen fu coal was not used properly. It would be of great importance to make the char into formcoke, because the ratio of coking coal could be reduced, and the source of coking coal could be expanded.In our study, when char produced in the pyrolysis of Shen fu coal was used as the raw material and coal pitch was used as the binder, the influence of molding process, pretreatment process and carbonizing process on the quality of formcoke was discussed. Morever, the bonding effect of the modified coal pitch, coal tar and the modified coal tar was studied.It was found that the particle size proportion of the char, the molding pressure and the molding temperature of formcoke had an important effect on the compressive strength. The results showed that when choosing char produced in the pyrolysis of Shen fu coal as the raw material, it was best to set the particle size distribution as follows,25%¡«15% of 0.9¡«0.45mm and 55%¡«65% of<0.45mm. When using coal pitch as the binder, the compressive strength of formcoke produced at 100¡æwithout addition of H2O was 3¡«5 times larger than that of formcoke produced at room temperature with adding H2O. Meanwhile, from the study on molding pressure of formcoke, we could see it was not the larger the better, the optimizum in this study was 19.4MPa.The amount and types of the binder was one of the key factors which affect the compressive strength. The results showed that the maximum compressive strength could be obtained either when the addition of coal tar was 21%, or when the addition of modified tar was 19%, and it could also be got either when the addition of pitch was 17%, or when the addition of modified pitch was 15%. The results showed that although the amount of modified binder was decreased, the compressive strength increased. The largest compressive strength of formcoke produced by using modified tar as the binder was 7.555MPa.From the thermogravimetric analysis of char and binders, we could know their thermal characteristics. It was revealed that in the whole analytical process, the weight loss of char was not more than 9%, and the residual weight at N2 atmosphere than that without N2 atmosphere. When the temperature was above 600¡æ, thermal decomposition and polycondensation reaction of the binders tended to stop gradually, and the losing weight was close to 0. The residual weight of the modified pitch was about 5% higher than that of the pitch. The weight loss of the coal tar reached 85%.The pretreatment process had great effects on compressive strength. In this article, the influence of air flow, pretreatment temperature and pretreatment time on the formcoke qulity was studied, and the optimum pretreatment conditions were fixed.The study on carbonization revealed that the heating rate, the final temperature of carbonization and the time for keeping the final temperature had great effect on the compressive strength. However, if the heating rate was very fast, the formcoke would generate fissure, and the compressive pressure would drop. With the rising of the final temperature of carbonization, the compressive pressure increased. Keeping the final temperature for a certain time was of benefit to enhance the compressive pressure of formcoke.According to the result of the experiment, a coke oven with the type of double-layer heel tap charing room was designed. This oven could improve a technical selection owing to its¡¯ reasonable thermal efficiency, good quality of formed coke and it is environmentally friendly.
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