本文選題：氣流分級　切入點：兩相流　出處：《中國海洋大學(xué)》2015年碩士論文

【摘要】：隨著超細(xì)粉體技術(shù)的發(fā)展,現(xiàn)代工業(yè)對于碳化硅等磨料的粒徑要求越來越小、粒度分布也越來越窄,對于分級設(shè)備性能的要求也越來越高。FL450型氣流分級機作為常用的碳化硅顆粒的分級機設(shè)備,弄清其工作原理,操作參數(shù)、設(shè)備結(jié)構(gòu)參數(shù)、物料及介質(zhì)性質(zhì)以及設(shè)備放大效應(yīng)對氣流分級機分級效果的影響規(guī)律,對分級機結(jié)構(gòu)和操作條件的優(yōu)化,提高設(shè)備的分級效率具有重要意義。本文采用數(shù)值模擬的方法,利用Fluent軟件研究對FLA50型氣流分級機分級碳化硅的過程就行研究分析。通過采用離散相模型模擬氣流分級機內(nèi)部的氣固兩相流,使用隨機軌道模型模擬不同粒徑顆粒在分級機內(nèi)的運動軌跡。利用構(gòu)建好的氣流分級機模型,模擬了不同轉(zhuǎn)速和風(fēng)量、不同葉輪結(jié)構(gòu)和導(dǎo)流錐結(jié)構(gòu)、不同密度材料對分級機內(nèi)部流場的速度分布的影響以及對分級過程的影響,利用其對分級結(jié)果的影響規(guī)律,根據(jù)生產(chǎn)要求對現(xiàn)有分級操作做出合理的優(yōu)化設(shè)計。得到結(jié)論如下：(1)使用離散相模型和隨機軌道模型描述氣流分級機的分級過程是可行的。(2)本文在忽略顆粒間相互作用的情況下,研究不同粒徑顆粒在分級機內(nèi)部的分級過程,顆粒分級時依然出現(xiàn)了“魚鉤效應(yīng)”,說明“魚鉤效應(yīng)”的出現(xiàn)與顆粒在分級過程的中受力情況有關(guān),需要進一步去研究。本文不支持“魚鉤效應(yīng)”由分級過程中顆粒間的團聚造成這一結(jié)論。(3)固定風(fēng)量調(diào)整分級葉輪轉(zhuǎn)速,在適當(dāng)范圍提高轉(zhuǎn)速能夠使得分級產(chǎn)品的集中度和收率變高而不影響產(chǎn)品分級效果。當(dāng)轉(zhuǎn)速超出適當(dāng)范圍時,產(chǎn)品分割粒徑d50會下降,分級效果變差；固定分級葉輪轉(zhuǎn)速調(diào)整風(fēng)量,改變風(fēng)量嚴(yán)重影響產(chǎn)品收率。(4)過少的葉片數(shù)量和過厚的葉片都會使得分級過程的分級效果變差甚至沒有分級效果。在保證分級效果的前提下,使用葉片數(shù)量72片,厚度4mm的分級葉輪較原來的生產(chǎn)過程使用的葉輪產(chǎn)品回收率高；導(dǎo)流錐直徑對分級結(jié)果影響較大,存在一個最優(yōu)直徑使得分級效果最好。(5)不同密度的物料的在分級機內(nèi)的分級效果是不一樣的,密度為2300kg/m3～4000kg/m3間的物料,密度越大分級效果越好,密度越小分級效果越差。(6)當(dāng)介質(zhì)溫度由15℃升高到145℃時,會增加大顆粒穿過分級葉輪的比例,不利于分級。(7)分級設(shè)備放大會導(dǎo)致分級產(chǎn)品的收率降低,對分級產(chǎn)品的影響較小。
[Abstract]:With the development of superfine powder technology, modern industry for silicon carbide abrasive particle size smaller, narrower grain size distribution, for the classification of equipment performance requirements are increasingly high.FL450 type air classifier as silicon carbide particles commonly used classifier equipment, understand its working principle, operation parameters, equipment structure parameters. Materials and media properties and influence effect on the amplification equipment air classifier classification efficiency, optimization of classifier structure and operating conditions, has important significance to improve the classification efficiency of the equipment. By using numerical simulation method, this research, by using the Fluent software of FLA50 type air classifier classification of silicon carbide on air classifier simulation analysis. The gas-solid two-phase flow by using the discrete phase model, using stochastic trajectory model of particles with different diameters in the classifier The trajectory. Using air classifier model constructed, simulation of different speed and air volume, different impeller structure and guide cone structure, the influence of different material density on the internal flow field of the velocity distribution of the classifier and the influence on the classification process, using its influence to the classification results, according to the production requirements to make reasonable design of the existing grading operation. The conclusions are as follows: (1) classification process using the discrete phase model and the stochastic model to describe the air classifier is feasible. (2) in this paper, ignoring the interaction between particles, the classification process of particles with different diameters in the classifier internal, particle classification still appears the "fish hook effect" that, "fish hook effect" and the stress in the particle grading process, it needs further studies. This paper does not support the "hook effect" by classification In the process of agglomeration of particles caused by this conclusion. (3) fixed air volume adjustment speed to improve the speed of impeller, the concentration and yield of high grade product change without affecting the product classification effect in the appropriate range. When the speed exceeds the proper range, product cut size D50 will decline, grading effect becomes worse; fixed grading impeller speed adjust the air volume, air volume change seriously affect the yield of the product. (4) leaf number and leaf thickness is too small will make the classification effect of classification process variation or no classification effect. Under the premise of ensuring the classification effect, blade number is 72, the recovery of impeller product grading impeller with the thickness of 4mm is the original production process using high rate; guide cone diameter on the classification results are affected, there is an optimal diameter makes the classification best. (5) materials of different density in classifier classification The effect is not the same, the density is 2300kg/m3 ~ 4000kg/m3, the material density is better classification effect, the smaller the density classification effect is worse. (6) when the medium temperature increased from 15 degrees to 145 degrees, will increase the proportion of large particles through the impeller, is not conducive to the classification (7) classification equipment. Amplification leads to graded product yield reduced, less impact on the classification of the product.

【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ051.8

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