本文選題：同心雙軸攪拌器 + 粘稠體系�。� 參考：《浙江大學(xué)》2015年碩士論文

【摘要】：氣液攪拌反應(yīng)器廣泛應(yīng)用于化工、食品、化妝品加工、生物化學(xué)、污水處理、聚合等過程工業(yè)中。對攪拌器的氣液分散和混合性能進(jìn)行研究,對于深入理解氣液分散、混合以及放大機(jī)理,進(jìn)而指導(dǎo)工業(yè)生產(chǎn)具有很大的幫助。文獻(xiàn)中已有大量關(guān)于攪拌器氣液分散和混合特性的研究,但仍存在很多不足之處：首先,研究體系大多為水／低粘液體-空氣體系,而實際工業(yè)生產(chǎn)中體系的物性復(fù)雜的多,粘度較大或者為非牛頓流體等；其次,研究對象幾乎全為單軸攪拌器,而且粘稠體系下局部參數(shù)的實驗測量也很是欠缺。因此,對同心雙軸攪拌器在粘稠體系下的氣液分散和混合特性進(jìn)行系統(tǒng)研究很有必要。本文創(chuàng)新設(shè)計了適用于同心雙軸氣液攪拌的新型框式外槳和新型進(jìn)氣系統(tǒng)。實驗過程中,在比較了同心雙軸攪拌器和單軸攪拌器氣液分散特性優(yōu)劣的基礎(chǔ)上,系統(tǒng)研究了操作條件(轉(zhuǎn)速、通氣量、內(nèi)外槳的轉(zhuǎn)動模式)、槳型組合(三種槳型組合：框式外槳+Rushton/SBT-6/PBT-6)、不同粘度(最大粘度0.3Pa·s)對同心雙軸攪拌器在粘稠體系下氣液分散和混合特性的影響。本文還采用計算流體力學(xué)(CFD)方法,對三種槳型組合同心雙軸攪拌器在粘稠體系下(最大粘度0.8Pa·s)的氣液分散和混合特性進(jìn)行了研究,得到了宏觀流場、局部氣含率、局部氣泡尺寸、剪切速率等信息,并進(jìn)行分析,很好的驗證和補(bǔ)充了實驗研究的內(nèi)容,對深入理解氣液分散和混合機(jī)理起到了很好的幫助作用。結(jié)果發(fā)現(xiàn)：a)反向轉(zhuǎn)動模式下的雙軸攪拌器相對單軸攪拌器氣液分散性能優(yōu)勢明顯；b)相同條件下,三種槳型組合中,框式外槳和Rushton槳的組合氣液分散和混合特性最好。并且,內(nèi)外槳反向轉(zhuǎn)動模式優(yōu)于同向轉(zhuǎn)動；c)一定范圍內(nèi),粘度增大,整體氣含率增大,但粘度的增大對整釜內(nèi)氣液分散的均勻性有不利的影響,導(dǎo)致近壁區(qū)局部氣含率下降；d)一定條件下,轉(zhuǎn)速越大,氣液分散性能越好,整體氣含率和局部氣含率均越大；e)通氣量對整體參數(shù)和局部參數(shù)的影響相對較復(fù)雜。雖然,一定轉(zhuǎn)速下,通氣量越大,槳葉背部形成的氣穴結(jié)構(gòu)越大,攪拌槳的泵送能力越差,越不利于氣泡在釜內(nèi)的均勻分散。但是,當(dāng)轉(zhuǎn)速保持在泛點轉(zhuǎn)速之上時,增大通氣量,氣液分散狀態(tài)仍較好,整體氣含率和局部氣含率均有一定程度的提高。模擬得到的結(jié)果和實驗值對比發(fā)現(xiàn),總體來說,模擬值和實驗值吻合良好,并且,模擬結(jié)果對解釋實驗現(xiàn)象和加深對氣液分散和混合機(jī)理的理解幫助很大。
[Abstract]:Gas-liquid stirrers are widely used in the process of chemical industry, food, cosmetic processing, biochemistry, sewage treatment, polymerization and other process industries. The study of the gas-liquid dispersion and mixing performance of the agitator is very helpful for understanding the gas and liquid dispersion, mixing and amplification mechanism, and then refers to the industrial production. In the study of the gas and liquid dispersion and mixing characteristics of the agitator, there are still a lot of shortcomings. First, most of the research systems are water / low viscosity liquid air system, and in actual industrial production, the system has more complex physical properties, larger viscosity or non Newtonian fluid. Secondly, the research object is almost all the uniaxial agitator, and the viscous body is almost all. Therefore, it is necessary to systematically study the gas-liquid dispersion and mixing characteristics of the concentric biaxial agitator in the viscous system. A new type of frame propeller and a new type of inlet system suitable for the concentric biaxial gas-liquid agitation are innovated and designed in this paper. In the experiment, the concentric double shaft agitation is compared. On the basis of the advantages and disadvantages of the gas-liquid dispersion characteristics of the mixer and the uniaxial agitator, the operating conditions (rotational speed, ventilation volume, and the rotation mode of the inner and outer paddles), the combination of the paddle type (three types of paddle combinations: the frame type outer paddle +Rushton/SBT-6/PBT-6), and the different viscosity (maximum viscosity 0.3Pa s) of the concentric biaxial agitator in the viscous system and the dispersion and mixing of gas and liquid under the viscous system are systematically studied. This paper also uses computational fluid dynamics (CFD) method to study the gas-liquid dispersion and mixing characteristics of three types of propeller type combined concentric biaxial agitators in a viscous system (maximum viscosity 0.8Pa s). The macroscopic flow field, local gas holdup, local bubble size, shear rate and other information are obtained, and the analysis is a good verification. And supplemented the content of the experimental study, it is a good help to understand the mechanism of gas and liquid dispersion and mixing. Results: a) the gas-liquid dispersion performance of the dual axis agitator under the reverse rotation mode is obvious; b) under the same condition, the combined gas-liquid of the frame type and the Rushton paddles in the three type of propeller combinations. The characteristics of dispersion and mixing are best. Moreover, the reverse rotation mode of the inner and outer paddles is superior to the same direction rotation; c) in a certain range, the viscosity increases and the holistic gas holdup increases, but the increase of the viscosity has an adverse effect on the uniformity of the gas and liquid dispersion in the whole kettle, resulting in the decrease of the local gas holdup in the near wall region; under certain conditions, the greater the rotational speed and the dispersion performance of the gas and liquid. The better, the greater the gas holdup and the local gas holdup, the greater the overall gas holdup and the local gas holdup, the more complex the influence of the E) on the overall and local parameters. Although the larger the ventilation volume is, the greater the aeration, the greater the cavitation structure of the blade back, the worse the pumping capacity of the agitator, the more unfavorable to the uniform dispersion of the bubbles in the kettle. When the speed is above the point, the volume of aeration is increased, the dispersion state of the gas and liquid is still better, the overall gas holdup and the local gas holdup are improved to a certain extent. The simulated results are in good agreement with the experimental values compared with the experimental values. The simulation results can explain the experimental phenomena and deepen the dispersion and mixing mechanism of the gas and liquid. Understanding is very helpful.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ051.72

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本文編號：1968552