【摘要】：超聲反應(yīng)器是實(shí)現(xiàn)聲化學(xué)反應(yīng)及進(jìn)行聲化學(xué)研究的關(guān)鍵設(shè)備,是指在超聲波的作用下進(jìn)行聲化學(xué)反應(yīng)的系統(tǒng)。超聲反應(yīng)器具有操作簡單,性能穩(wěn)定優(yōu)良和效率高等特點(diǎn),其應(yīng)用研究和開發(fā)日益受到人們的重視。本文以實(shí)驗(yàn)室的發(fā)明專利樣機(jī)——連續(xù)式多頻超聲反應(yīng)槽作為反應(yīng)容器,以純凈水及酸化油體系為研究對象,探究超聲反應(yīng)器中聲場特性隨超聲頻率及組合、超聲功率、流體中固含量的變化規(guī)律及其在反應(yīng)器中的分布規(guī)律,旨在探究超聲反應(yīng)器中聲場分布規(guī)律對最佳反應(yīng)條件、聲化學(xué)產(chǎn)率的重要影響,并為推動聲化學(xué)技術(shù)由實(shí)驗(yàn)室規(guī)模向工業(yè)化應(yīng)用提供指導(dǎo)。本論文主要工作及研究結(jié)果如下：(1)通過超聲波聲強(qiáng)測定儀對超聲反應(yīng)器的聲場分布進(jìn)行了測定,發(fā)現(xiàn)：長度寬度方向、軸向及平面處的聲場有相似的分布規(guī)律,除換能器輻射面和器壁附近聲強(qiáng)值較高外,總體聲場分布均勻；流體流量(0-40L/h)和溫差變化(25-40℃)對聲場分布影響較��；反應(yīng)器形狀、換能器安裝位置及超聲功率對聲場分布影響較大：靠近換能器輻射面的聲強(qiáng)值較高,換能器輸入功率增加時聲強(qiáng)值也相應(yīng)的明顯變化；比較酸化油和純水兩種介質(zhì)在連續(xù)超聲反應(yīng)器中同等實(shí)驗(yàn)條件下的聲能分布規(guī)律,發(fā)現(xiàn)油體中聲強(qiáng)衰減較大,這是油的粘滯系數(shù)較高所致,但整體聲場分布規(guī)律與水介質(zhì)中的相似。(2)在水體系中加入細(xì)小固體顆粒(活性炭),并維持在懸浮狀態(tài)下,聲強(qiáng)變化幅度縮小為7%(未加微細(xì)顆粒時變化幅度高達(dá)40%),可以明顯改善聲場分布均勻性。對活性炭顆粒粒徑和添加量進(jìn)行了考察,35kHz的反應(yīng)器的測試結(jié)果表明：最佳顆粒粒徑為200目(75μm),添加量為1.25kg/m3。在該條件下測定聲強(qiáng)分布,發(fā)現(xiàn)之前輻射面附近和壁面處聲壓值不穩(wěn)定的現(xiàn)象已不存在,其與超聲的協(xié)同作用達(dá)到最佳值；聲強(qiáng)隨輸入功率的變化更具規(guī)律性,這使得功率對超聲反應(yīng)器的作用更容易控制,為進(jìn)一步改善傳質(zhì)反應(yīng)提供了一定的措施。(3)以高酸值酸化油為原料進(jìn)行生物柴油連續(xù)制備實(shí)驗(yàn),得知在多頻超聲作用(15-25-35-40kHz),各輸入功率200W條件下(醇油比6：1、催化劑(KOH)用量1.2%(質(zhì)量分?jǐn)?shù))、反應(yīng)時間54min、溫度為室溫等條件均相同),生物柴油產(chǎn)率(95.34%)較無超聲輻射下產(chǎn)率(52.18%)提高了43.16%；較單頻輻射(15kHz)時產(chǎn)率(87.95%)提高了7.39%,進(jìn)一步驗(yàn)證了聲強(qiáng)大小和聲場分布均勻性對強(qiáng)化傳質(zhì)的重要性。(4)通過對超聲場中的空化氣泡運(yùn)動方程進(jìn)行數(shù)值模擬,發(fā)現(xiàn)：隨超聲頻率增大,空化泡半徑變化幅度減小,空化泡達(dá)到最大半徑所需時間明顯變長,空化效應(yīng)減弱；隨聲強(qiáng)的增大,空化效應(yīng)增強(qiáng)；粘度較大的流體對空化泡運(yùn)動的阻尼作用更為明顯,可通過增加輸入功率的方式達(dá)到預(yù)定的聲強(qiáng)或空化效果。本文研究結(jié)果表明,超聲反應(yīng)器內(nèi)聲強(qiáng)大小及其分布均勻性對強(qiáng)化傳質(zhì)過程意義重大。通過具體的生物柴油連續(xù)制備實(shí)驗(yàn)對所做聲場分布描述進(jìn)行了驗(yàn)證,并對超聲場中空化泡的運(yùn)動進(jìn)行了相關(guān)的數(shù)值模擬,這些研究都為聲化學(xué)反應(yīng)器的性能優(yōu)化提供了理論依據(jù)和技術(shù)參考。
[Abstract]:Ultrasonic reactor is the key equipment for the realization of sonochemical reaction and sonochemical research. It refers to the sound chemical reaction system under the action of ultrasonic wave. The ultrasonic reactor has the characteristics of simple operation, good performance stability and high efficiency. The application research and development of the ultrasonic reactor is paid more and more attention. This paper is based on the invention patent of the laboratory. The prototype, a continuous multi frequency ultrasonic reaction tank as a reaction vessel, takes pure water and acidified oil as the research object, and explores the characteristics of sound field in the ultrasonic reactor with ultrasonic frequency and combination, ultrasonic power, the law of the change of solid content in the fluid and the distribution rules in the reactor. The aim is to explore the distribution law of sound field in the ultrasonic reactor. The important influence of the optimum reaction conditions and the sound chemical yield is provided to promote the application of the acoustic chemistry technology from the laboratory scale to the industrial application. The main work and research results of this paper are as follows: (1) the sound field distribution of the ultrasonic reactor is measured by the ultrasonic intensity measuring instrument, and the direction of length, the axis and the plane are found. The sound field has a similar distribution law. The sound field distribution is uniform except the high acoustic intensity near the transducer and the wall of the transducer. The fluid flow (0-40L/h) and temperature difference (25-40 degrees) have little influence on the distribution of sound field; the shape of the reactor, the installation position of the transducer and the ultrasonic power have great influence on the distribution of sound field: near the transducer radiation The sound intensity of the surface is higher and the intensity of the transducer is increased. The sound energy distribution under the same experimental conditions in the acidified oil and the two kinds of pure water in the continuous ultrasonic reactor shows that the sound intensity attenuates greatly in the oil body, which is the result of the higher viscosity of the oil, but the distribution law of the whole sound field and the water. The similarity in the medium. (2) adding fine solid particles (active carbon) in the water system and maintaining the sound intensity in the suspension state, the amplitude of the sound intensity is reduced to 7% (when the change amplitude is up to 40% without fine particles), and the distribution uniformity of the sound field can be improved obviously. The particle size and addition of activated carbon particles are investigated and the test results of the 35kHz reactor are tested. The results show that the optimum particle size is 200 mesh (75 mu m) and the addition amount of 1.25kg/m3. is used to determine the sound intensity distribution under this condition. The phenomenon that the acoustic pressure is unstable near the surface of the radiation surface and the wall surface has not existed, and the synergistic effect of the acoustic intensity is the best. The sound intensity is more regular with the change of the input power, which makes the power to ultrasonic inverse. The function of the stress is easier to control and provides some measures to further improve the mass transfer reaction. (3) a continuous preparation experiment of biodiesel is carried out with high acid value acidified oil as raw material. It is known that under the multi frequency ultrasonic action (15-25-35-40kHz) and the input power of 200W (alcohol oil ratio 6:1, catalyst (KOH) dosage 1.2% (mass fraction), reaction time 54mi) N, with the same temperature as room temperature, the yield of biodiesel (95.34%) increased by 43.16% compared with that without ultrasonic radiation (52.18%), and the yield (87.95%) increased by 7.39% compared with single frequency radiation (15kHz). The importance of the sound intensity and the uniformity of sound field distribution to the mass transfer was further verified. (4) through the cavitation bubble movement in the ultrasonic field The numerical simulation of the equation shows that as the ultrasonic frequency increases, the radius of cavitation bubble decreases, the time required for the cavitation bubble to reach the maximum radius is obviously longer, the cavitation effect decreases, and the cavitation effect increases with the increase of sound intensity, and the damping effect of the fluid with larger viscosity is more obvious, and the input power can be increased by increasing the input power. The results show that the sound intensity and distribution uniformity in the ultrasonic reactor are of great significance to the enhancement of mass transfer process. The description of the sound field distribution is verified by the continuous preparation experiment of biodiesel, and the motion of the hollow bubble in the ultrasonic field is related. These studies provide theoretical basis and technical reference for the performance optimization of sonochemical reactors.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ052;O644.3

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 王雙維;馮若;史群;;小尺度混響場中超聲化學(xué)效應(yīng)的研究[J];自然科學(xué)進(jìn)展;1992年03期

，

本文編號：2145444