不同粒级煤在振动流化床中分层行为的研究

发布时间：2018-05-16 22:44

本文选题：振动流化床 + 加重质　；参考：《中国矿业大学》2015年硕士论文

【摘要】：日益严峻的环境问题要求煤的洗选必须大力加强,而目前水资源匮乏的局势又制约着传统湿法选煤的发展,因此,亟需高效的干法分选技术,空气重介质流化床选煤工艺已经被证明可以有效分选+6mm粒级煤,E值为0.05-0.08,但对于粒度小于6mm粒级的细粒煤,传统流化床不能满足分选要求,将振动能量引入流化床可显著提高流化床均匀稳定性和对细粒煤的分选效果。本论文搭建了间歇式振动流化床分选系统,通过绘制流化曲线的方法研究了在不同振动强度和不同加重质的情况下的流化床的流化特性,研究证明,振动能量的引入能显著减小最小流化气速,降低压力波动,增加床层稳定性;磁铁矿粉中加入石英砂作为混合加重质时,最小流化速度和压降随着石英砂质量比的增大而减小。在对6-3mm粒级煤做单因素探索试验的基础上,利用Design-expert软件响应曲面法中的Box-Behnken分析方法分别对6-3mm,3-2mm,2-1mm,1-0.5mm四个粒级做三因素三水平正交试验,研究指出,分选效果随粒度的减小而变差,对于6-3mm粒级煤,在保证精煤灰分低于4.65%的情况下,可燃体回收率高达86%;对于1-0.5mm粒级煤,在保证精煤灰分低于18%的情况下,可使可燃体回收率维持在70%左右。通过将四个粒级煤按质量比等量混合研究振动流化床对混合粒级煤的分选效果,由试验结果可知,振动床对3-2mm,2-1mm,1-0.5mm三个粒级的分选效果优于分级入选,说明6-3mm粒级煤的存在可以提高振动流化床对3-0.5mm粒级煤的分选效果。在磁铁矿粉中加入不同质量的石英砂作为混合加重质时,研究了振动流化床对2-1mm粒级煤的分选效果,结果为当磁铁矿粉与石英砂质量比值为2:0.3时分选效果最佳,此时精煤灰分8.47%,可燃体回收率91.86%,因此在磁铁矿粉中掺入定量的石英砂可提高振动流化床对细粒级煤的分选效果。通过混合加重质流化床对四个粒级煤的分选浮沉试验确定了每个粒级的E值,分选结果显示振动流化床对6-3mm,3-2mm,2-1mm,1-0.5mm四个粒级煤分选的E值分别为:0.090,0.127,0137,0.270 g/cm3。
[Abstract]:The increasingly severe environmental problems require that the washing and separation of coal must be greatly strengthened, and the current situation of water resources shortage restricts the development of traditional wet coal preparation. Therefore, it is urgent to develop efficient dry separation technology. It has been proved that the air heavy medium fluidized bed coal preparation process can effectively separate the 6mm granular coal with E value of 0.05-0.08, but the traditional fluidized bed can not meet the separation requirements for the fine coal with particle size smaller than 6mm. The uniform stability of fluidized bed and the separation effect of fine coal can be improved by introducing vibration energy into fluidized bed. In this paper, an intermittent vibrating fluidized bed separation system is built. The fluidization characteristics of fluidized bed with different vibration intensity and different aggravation are studied by drawing fluidization curve. The introduction of vibration energy can significantly reduce the minimum fluidized gas velocity, reduce the pressure fluctuation, and increase the stability of the bed, and the minimum fluidization velocity and pressure drop decrease with the increase of the mass ratio of quartz sand when the quartz sand is added into the magnetite powder as the mixed admixture. On the basis of the single factor exploration test of 6-3mm grained coal, using the Box-Behnken analysis method of Design-expert software response surface method, three factors and three levels orthogonal tests were made on four grain grades of 6-3mm / 3-2mm / 2-1mm / (1-0.5mm) respectively. It is pointed out that the separation effect becomes worse with the decrease of particle size. For 6-3mm grained coal, the recovery rate of combustible coal is as high as 86% when the ash content of clean coal is less than 4.65%, and 70% for 1-0.5mm coal with ash content less than 18%. The separation effect of vibrating fluidized bed on mixed coal is studied by mixing the four grained coals in the same quantity according to mass ratio. From the experimental results, it can be seen that the separation effect of vibrating bed on 3-2mm / 2-1mm / 1-0.5mm is better than that of classifying. It shows that the existence of 6-3mm granular coal can improve the separation efficiency of 3-0.5mm granular coal by vibrating fluidized bed. The separation effect of 2-1mm grained coal by vibrating fluidized bed was studied when different quality quartz sand was added to magnetite powder as mixed weight. The results showed that the separation effect was the best when the mass ratio of magnetite powder to quartz sand was 2: 0.3. The ash content of clean coal is 8.47 and the recovery rate of combustible coal is 91.86. Therefore, adding quantitative quartz sand into magnetite powder can improve the separation effect of fine coal in vibrating fluidized bed. The E value of each particle level was determined by flotation and subsidence test of mixed aggravation fluidized bed for four grained coals. The separation results showed that the E value of vibrating fluidized bed for 6-3mm / 3-2mm / 2-1mm / (1-0.5mm) separation of four grained coals was: 1 / 0.090 / 0.127 / 0137/ 0.270 g / cm ~ (3), respectively.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD94

【参考文献】