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下噴式環(huán)流反應器流動特性研究

發(fā)布時間:2018-08-17 16:09
【摘要】:下噴式環(huán)流反應器(Reverse Jet Loop Reactor,簡稱RJLR)借助高速的射流和環(huán)流的相互作用,因而強化了流體的混合效果,提高了傳熱及傳質速率,改善了反應條件,是一種新型的高效多相反應裝置;谄浣Y構簡單、投資廉價、無轉動部件、密封性好及混合傳質傳熱性能好、操作維修以及工業(yè)放大容易等優(yōu)點,下噴式環(huán)流反應器特別適合于液-液、氣-液及氣-液-固等多相反應體系中。在化學化工、生物工程、環(huán)境保護等領域很快得到廣泛應用,具有良好的發(fā)展前景。但由于研究者在研究方法、測試手段、研究內容方面的不系統(tǒng),導致目前對該反應器的放大設計和優(yōu)化缺乏依據(jù),對環(huán)流反應器的操作規(guī)律更是缺乏研究。因此本文對下噴式環(huán)流反應器的流動特性進行了研究,主要的研究內容和結論如下:(1)空氣-水體系為研究對象,實驗研究了下噴式環(huán)流反應器的結構參數(shù)及操作參數(shù)對氣含率ε、吸氣量QG的影響規(guī)律。實驗結果表明,氣含率隨著表觀液速及表觀氣速的增加而增加;氣體吸入量隨著液體流量的增加和噴嘴位置的上升而增加。并根據(jù)實驗結果回歸了氣含率的關聯(lián)式如下:(2)在空氣-水體系下,實驗研究了下噴式環(huán)流反應器的啟動規(guī)律(環(huán)流啟動的最小液體流量弛以及環(huán)流維持的最小液體流量QLd等)。實驗結果表明,隨著噴嘴位置及導流筒直徑的升高,環(huán)流啟動的最小液體流量QLu以及環(huán)流維持的最小液體流量QLd都不斷的升高。隨著導流筒位置的下降,QLu稍微升高,而QLd逐漸降低。在氣體流量較低時(QG1.5m3/h),隨著氣體流量的增加,Qu以及QLd迅速下降,而在氣體流量較高時(QG1.5m3/h),氣體流量的變化對QLu以及QLd影響不大。并利用實驗數(shù)據(jù)對QLu以及QLd進行了關聯(lián),關聯(lián)式如下:(3)將粒子圖像測速法(Particle Image Velocimetry,簡稱PIV)和計算流體動力學(Computational Fluid Dynamics,簡稱CFD)相結合,研究下噴式環(huán)流反應器內部的速度場分布規(guī)律,并將速度的測量值與k-ε湍流模型模擬值進行了對比。結果表明,導流筒內速度呈拋物線分布,隨著噴嘴位置的下降,拋物線圖形越陡,環(huán)隙的速度先降低后升高;隨著噴嘴的速度升高時,反應器內各位置的速度值均升高,實驗和模擬的結果的一致,證明了模型的正確性。(4)將下噴式環(huán)流反應器應用于2,4-二硝基甲苯(2,4-dinitrotoluene,簡稱DNT)催化加氫合成2,4-甲苯二胺(2,4-tolylene diamine,簡稱TDA)反應,對反應器的體積、循環(huán)量以及換熱進行了設計,并與相同反應條件下的攪拌釜式反應器進行了比較。實驗表明,采用下噴式環(huán)流反應器的體積約為攪拌釜式反應器的10%。同時模擬了反應器的體積和換熱器的面積隨著循環(huán)比的變化規(guī)律,最后確定了反應系統(tǒng)的循環(huán)比為80,換熱器面積為355m2。
[Abstract]:Reverse Jet Loop Reactor (RJLR) is a new type of multiphase reactor with high efficiency, which is characterized by its simple structure, low investment, no rotating parts and sealing. Down-jet loop reactor is especially suitable for liquid-liquid, gas-liquid and gas-liquid-solid systems. It has been widely used in chemical, biological engineering, environmental protection and other fields, and has a good development prospect. The unsystematic research methods, testing methods and research contents lead to the lack of basis for the scale-up design and optimization of the reactor, and the lack of research on the operating rules of the loop reactor. The experimental results show that the gas holdup increases with the increase of superficial liquid velocity and superficial gas velocity, and the gas suction increases with the increase of liquid flow rate and nozzle position. According to the experimental results, the correlation of gas holdup was regressed as follows: (2) In the air-water system, the start-up law of the downspout loop reactor (the minimum liquid flow relaxation and the minimum liquid flow QLd maintained by the circulation) was experimentally studied. The minimum liquid flow rate QLu and the minimum liquid flow rate QLd maintained by the circulating current both increase continuously. With the decrease of the position of the guide tube, QLu increases slightly, but QLd decreases gradually. At the lower gas flow rate (QG1.5m3/h), Qu and QLd decrease rapidly with the increase of gas flow rate, but at the higher gas flow rate (QG1.5m3/h), the change of gas flow rate is obvious. Qlu and QLd have little effect. The experimental data are used to correlate Qlu and QLd. The correlations are as follows: (3) The particle image velocimetry (PIV) and computational fluid dynamics (CFD) are combined to study the velocity field distribution in the downspout loop reactor. The measured velocity was compared with the simulated value of k-e turbulence model. The results show that the velocity in the draft tube is parabolic. With the decrease of the nozzle position, the parabolic figure becomes steeper, and the velocity in the annulus first decreases and then rises. (4) The downjet loop reactor was applied to the catalytic hydrogenation of 2,4-dinitrotoluene (DNT) to synthesize 2,4-tolylene diamine (TDA), and the reactor volume, circulating capacity and heat transfer were designed. The experimental results show that the volume of the down-jet loop reactor is about 10% of that of the stirred tank reactor. Simultaneously, the variation of the reactor volume and the area of the heat exchanger with the circulation ratio is simulated. Finally, the circulation ratio of the reaction system is 80 and the area of the heat exchanger is 355m2.
【學位授予單位】:青島科技大學
【學位級別】:碩士
【學位授予年份】:2015
【分類號】:TQ052

【參考文獻】

相關期刊論文 前2條

1 劉亞娟;張金利;;液固下噴自吸環(huán)流反應器流體力學特性[J];化學工業(yè)與工程;2007年03期

2 閆少偉;范輝;于智慧;梁川;李忠;孟凡敬;;二硝基甲苯加氫制甲苯二胺催化劑的研究進展[J];化工進展;2013年02期

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