本文關鍵詞： 多相流反應器 容積傳質系數(shù) 傳質模型 熱態(tài) 多層槳　出處：《北京化工大學》2015年博士論文　論文類型：學位論文

【摘要】：多相攪拌反應器被廣泛應用于生物化工、石油化工、礦物化工、精細化工及環(huán)境工程等行業(yè),為生物發(fā)酵、石油冶煉、選礦工程、制藥、污水處理等多種過程工業(yè)中涉及到的催化加氫、鹵化和氧化等反應提供一個較為均一的濃度場和能量分布場。在這些反應中,物料應充分接觸和混合以避免反應過程中局部反應物濃度過高或過低而引起的反應過快或中止。在快速反應中,傳質速率常常成為控制步驟,傳質性能直接影響產(chǎn)品質量和產(chǎn)量,是評價、設計和優(yōu)化攪拌反應器的一個重要參數(shù)。目前反應器內(nèi)傳質特性的研究還主要集中在常溫下,導致在進行反應器放大和設計時只能借鑒常溫研究結果和規(guī)律。本實驗室己開展的熱態(tài)操作條件下流體力學性能的研究表明熱態(tài)和常溫的規(guī)律有較大差別,這就不可避免地導致使用常溫下研究規(guī)律做指導的設計和放大與實際的熱態(tài)生產(chǎn)過程產(chǎn)生偏差。為了更好地指導實際生產(chǎn)中反應器的設計和放大,本文研究了熱態(tài)操作條件下不同體系的傳質性能。首先在以亞硫酸鈉溶液為液相的非凝并體系中,使用由六直葉半橢圓管葉渦輪槳(HEDT)和兩層上提操作方式的四寬葉翼形槳(WHU)組成的三層組合槳,通過亞硫酸鈉氧化法研究了熱態(tài)操作條件下(50-80℃)非凝并體系中的容積傳質系數(shù)(KLa)。結果表明,KLa隨著單位功耗、表觀氣速和溫度的增大而增大。定量得出表示KLa與單位功耗、表觀氣速和溫度關系的關聯(lián)式,關聯(lián)式中溫度、單位功耗和氣速的指數(shù)依次變小,這說明在非凝并體系中升高溫度可以明顯增大KLa,增大單位功耗比增大表觀氣速更利于提高KLa。在以水為液相的凝并體系中,研究了熱態(tài)操作條件下氣-液兩相體系中的氣液分散和傳質性能及加入玻璃珠的氣-液-固三相體系中的通氣攪拌功率及傳質性能。結果表明,氣-液兩相體系中,氣含率(sG)隨溫度升高而明顯降低,KLa受溫度的影響很小。依實驗數(shù)據(jù)關聯(lián)得不同溫度下的氣含率和KLa與溫度、功率和表觀氣速的經(jīng)驗關聯(lián)式。對比關聯(lián)式中的指數(shù)可以看出,溫度、表觀氣速和功耗對氣含率的影響依次減小,對KLa的影響依次增大。功耗對KLa的影響指數(shù)分別是表觀氣速和溫度對KLa影響指數(shù)的2倍和4倍。在氣-液-固三相體系中,固體顆粒的加入改變了溫度對KLa的影響規(guī)律,KLa隨著溫度的升高而增大。同時溫度的變化也影響固相濃度對KLa的影響,在常溫(25℃)下,KLa隨著CV的增加而減小,但隨著溫度的升高,這種減小的幅度減慢；在54℃,CV對KLa幾乎沒影響；在80℃,KLa隨著Cv的增大甚至有些增加；但整體而言,在40-80℃間,KLa隨著Cv的變化幅度基本在10%以內(nèi)。為了滿足工業(yè)用槳的多樣性,本文還研究了多種三層組合槳在不同操作條件下的傳質性能。使用槳型為HEDT,拋物線形葉片渦輪槳(PDT),WH和三葉翼形槳(CBY)。研究表明,通氣量較低時各種組合槳的kLa差別不大,但通氣量較大時差別明顯。表觀氣速較高時(uG=0.016-0.039 m·s-1), PDT+2WHD傳質效果最好,而HEDT+2WHU傳質效果最差。在相同功耗下,高轉速和大槳葉投影橫截面積的槳型組合利于傳質。得到了不同槳型的功率準數(shù)和傳質系數(shù)的關聯(lián)式。通過多變量分析方法得到了適用于高溫操作條件下凝并體系和非凝并體系的kLa模型kL模型。建立在小渦模型的基礎之上的kL模型,可以用來描述高溫下kL變化規(guī)律。高溫凝并體系下,kL模型中DL的指數(shù)與小渦模型中的指數(shù)0.5相近,但單位能量耗散率的指數(shù)卻由1/4減小為1/6,這是因為溫度的升高削弱了功耗對kL的影響。非凝并體系下的kL模型中擴散系數(shù)的指數(shù)明顯高于凝并體系。通過理論模型計算和分析了影響容積傳質系數(shù)的氣含率、氣泡尺寸、溶氧擴散系數(shù)、液相傳質系數(shù)和相界面積在不同溫度的變化關系,通過模型的理論計算值與實驗值的對比,驗證了模型的準確性。
[Abstract]:Multiphase stirred reactor is widely used in chemical, petrochemical, mineral chemical, fine chemical and environmental engineering industry, bio fermentation, petroleum refining, mineral processing engineering, pharmacy, sewage treatment and other industrial processes involved in the catalytic hydrogenation of halogenated and oxidation reaction to provide a more uniform the concentration field and energy distribution. In these reactions, the material should be fully contacted and mixed to avoid local reaction in the process of concentration is too high or too low and cause a rapid reaction or suspension. In fast reaction, the mass transfer rate usually is the controlling step, mass transfer performance affects the product quality and yield, is the direct evaluation. One of the most important parameters for the design and optimization of stirred reactors. The mass transfer characteristics of the reactor is mainly concentrated in the normal temperature, resulting in the design and reference only research reactor at ambient temperature The fruit and regularity. Hydrodynamic performance of the thermal operating conditions of the laboratory has been carried out under the show has a larger difference between the hot and normal rules, which inevitably leads to guide design and enlarge thermal production process and the deviation of the use of room temperature. In order to guide the actual production design and scale-up in the reactor better, this paper studied the mass transfer performance of different thermal system operating conditions. In the first phase of non coagulation system in sulfite solution, used by six straight blade turbine propeller semi elliptical tube (HEDT) and the two layer on mode of operation of the four wide blade hydrofoil impeller (WHU) three layer paddle, by oxidation of sodium sulfite on the thermal operating conditions (50-80 C) volumetric mass transfer coefficient and non condensate in the system (KLa). The results show that KLa with unit power consumption, increase of superficial gas velocity and temperature The quantitative increase. KLa and unit power consumption, table correlation of gas velocity and temperature, the temperature in the correlation unit, power consumption and speed index are smaller, indicating that the temperature in the non coagulation system can significantly increase KLa, increase the unit power consumption than the increase of superficial gas velocity is more conducive to improve KLa. with water as the liquid phase of the coagulation system, researched the thermal operating conditions of gas - liquid two-phase gas-liquid dispersion and mass transfer in the system of ventilation performance and adding glass beads of gas liquid solid three-phase system of stirring power and mass transfer performance. The results show that the gas-liquid two-phase system, gas containing rate (sG) decreased with the increase of temperature, KLa little affected by temperature. According to correlation of experimental data under different temperature of gas holdup and KLa correlations with temperature, power and superficial gas velocity. The contrast in the correlation index can be seen, temperature, superficial gas velocity Power and influence on gas holdup decreases, the impact on KLa power consumption increases. The influence of KLa index are superficial gas velocity and temperature effect on the KLa index of 2 times and 4 times. In the gas liquid solid system, solid particles could change the effect of temperature on KLa the KLa increases with the increase of temperature. At the same time, the temperature change can also influence the solid concentration of KLa, at room temperature (25 C), KLa decreases with the increase of CV, but with the increase of temperature, the decrease slowed; at 54 degrees, CV almost has no effect on KLa in 80; C, KLa increased with the increase of Cv and even some; but on the whole, at 40-80 DEG C, KLa with the range of Cv is less than 10%. In order to meet with the diversity of oar industry, this paper also studies the various mass transfer performance of three layer composite impellers under different operating conditions. The use of paddle type HEDT. Parabolic Linear blade turbine impeller (PDT), WH and trefoil hydrofoil impellers (CBY). The results show that kLa little difference in various combinations of propeller ventilation volume is low, but the difference is obvious. A large amount of ventilation at higher superficial gas velocity (uG=0.016-0.039 m s-1), the best PDT+2WHD HEDT+ 2WHU and the effect of mass transfer, mass transfer the difference in the same power consumption, impeller combination of high speed and high projected blade cross-sectional area for mass transfer. The correlation of different power paddle type number and mass transfer coefficient are obtained. The kLa model kL model is suitable for high temperature operation and coagulation system and coagulation system by multi variable analysis method. KL model based on small vortex model, can be used to describe the change rule of kL under high temperature. High temperature coagulation system, kL model, DL index and the index of 0.5 small vortex model is similar, but the unit energy dissipation rate index has decreased from 1/4 to 1/6, This is because the temperature weakens the impact on power of kL. KL model of non coagulation under the system of diffusion coefficient index was significantly higher than that of coagulation system. Through the theoretical model and the analysis of the impact of the volumetric mass transfer coefficient of gas holdup, bubble size, oxygen diffusion coefficient, liquid phase mass transfer coefficient and interfacial area changes in different temperature. The calculated values were compared with experimental values, to verify the accuracy of the model.

【學位授予單位】：北京化工大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ021.4

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