本文選題：氣固兩相流動　切入點：顆粒壓力脈動　出處：《東北電力大學》2015年碩士論文　論文類型：學位論文

【摘要】：近些年流化床技術在能源、化工等領域得到了十分廣泛的應用，但是由于流化床內(nèi)氣固兩相流動的復雜性和不確定性，使我們對氣固流化床內(nèi)流體的流動特性還不是完全認識。在流化床的設計和運行中顆粒壓力的脈動是十分重要的參數(shù)，顆粒壓力的特性是流化床內(nèi)其它各種特性的總體反映，而應用試驗方法研究流化床內(nèi)的氣固兩相流動、傳熱傳質(zhì)以及在放大等方面還有很多不足，通過應用fluent數(shù)值模擬的方法輔助試驗很好地解決了這些問題，也可以預測或檢驗實驗的結果，對流化床的應用具有理論指導作用。 本文應用歐拉-歐拉雙流體模型模擬了D類粒子的流態(tài)化過程。通過測定雙支腿流化床在相同布風板開孔率、不同的表觀風速、不同床高以及觀察高度時床內(nèi)顆粒壓力的脈動、顆粒濃度的變化以及雙支腿流化床的翻床現(xiàn)象的產(chǎn)生，對所得的數(shù)據(jù)進行傅里葉變換、小波變換的分析，得出床內(nèi)顆粒壓力的脈動具有低頻特性，顆粒濃度的變化具有寬頻特性，且床內(nèi)顆粒壓力的脈動主要是由床內(nèi)氣泡的生成、合并、破裂及兩側床腿內(nèi)顆粒相互交換造成的，，而雙支腿流化床內(nèi)翻床現(xiàn)象的產(chǎn)生主要是：在運行過程中兩側床內(nèi)顆粒壓力的不同使得床腿內(nèi)的顆粒相互交換，進而導致兩側床內(nèi)顆粒濃度的不同，這是一個正反饋過程，再不進行主動調(diào)節(jié)時，單側床內(nèi)顆粒濃度逐漸增大最后導致翻床。
[Abstract]:In recent years, fluidized bed technology has been widely used in the fields of energy and chemical industry, but because of the complexity and uncertainty of gas-solid two-phase flow in fluidized bed, The particle pressure fluctuation is a very important parameter in the design and operation of the fluidized bed, and the characteristics of the particle pressure is the overall reflection of the other characteristics in the fluidized bed. However, there are still many shortcomings in the study of gas-solid two-phase flow, heat and mass transfer and amplification in fluidized bed by using the experimental method. These problems are well solved by using the fluent numerical simulation method to assist the experiment. The experimental results can also be predicted or tested, which can be used to guide the application of fluidized bed. In this paper, Euler-Euler two-fluid model is used to simulate the fluidization process of D particles. Under different bed height and observed height, the fluctuation of particle pressure, the change of particle concentration, and the phenomenon of turning over bed in a fluidized bed with two legs are produced. The obtained data are analyzed by Fourier transform and wavelet transform. It is concluded that the pulsation of particle pressure in the bed has the characteristics of low frequency, the variation of particle concentration has the characteristic of wide frequency, and the pulsation of particle pressure in the bed is mainly caused by the formation, amalgamation and rupture of the bubbles in the bed, as well as the exchange of particles between the two sides of the bed leg. However, the phenomenon of double leg fluidized bed inversion is mainly caused by the different pressure of particles in both sides of the bed, which makes the particles exchange with each other, which leads to the difference of particle concentration in both sides of the bed, which is a positive feedback process. Without active adjustment, the particle concentration in the single bed increases gradually and finally results in the turning of the bed.
【學位授予單位】：東北電力大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ051.13

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