本文選題：油頁巖　切入點(diǎn)：計(jì)算流體力學(xué)　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：油頁巖作為一種“非常規(guī)油氣資源”,是本世紀(jì)重要的接替能源之一,因儲量豐富受到全球的廣泛關(guān)注。但由于油頁巖孔隙發(fā)達(dá)、含水量高的特點(diǎn),在干餾過程中常出現(xiàn)很多不利于生產(chǎn)的問題,所以,在油頁巖熱裂解前必須對其進(jìn)行干燥脫水處理。而氣流干燥因其處理量大、設(shè)備簡單、投資低等優(yōu)點(diǎn)在干燥處理中有著廣泛應(yīng)用。本文采用了流體動(dòng)力學(xué)模擬新技術(shù),對油頁巖的氣流干燥過程進(jìn)行了模擬研究,揭示了干燥過程中各種流場的詳細(xì)分布情況和變化趨勢,同時(shí),通過Fluent軟件中的用戶自定義(user defined functions)功能對軟件中的物理模型進(jìn)行二次開發(fā),創(chuàng)建了更符合油頁巖氣流干燥過程的傳熱、傳質(zhì)計(jì)算模型。對模擬結(jié)果進(jìn)行系統(tǒng)分析的同時(shí),還分別進(jìn)行了冷態(tài)下的中試實(shí)驗(yàn)和熱態(tài)下的實(shí)驗(yàn)室實(shí)驗(yàn),將氣流管動(dòng)力學(xué)模擬、氣流干燥過程熱力學(xué)模擬的模擬結(jié)果分別和實(shí)驗(yàn)結(jié)果進(jìn)行對比,模擬結(jié)果和實(shí)驗(yàn)數(shù)據(jù)吻合較好,證明了模擬結(jié)果的可靠性和自建模型的正確性。對氣流干燥管的動(dòng)力學(xué)模擬和實(shí)驗(yàn)研究表明：對料氣質(zhì)量比非常低的稀相輸送狀態(tài)而言,可認(rèn)為顆粒之間沒有相互干擾和影響,所以應(yīng)使用歐拉-拉格朗日算法來模擬顆粒的運(yùn)動(dòng)特性,即Fluent當(dāng)中的離散相模型(DPM);將進(jìn)氣方式改為兩側(cè)進(jìn)氣,或者在氣流管底部增加傾斜角度合適的倒錐形縮孔,均可明顯改善單側(cè)進(jìn)氣時(shí)易出現(xiàn)的偏流現(xiàn)象,但縮孔結(jié)構(gòu)也會(huì)大幅增加設(shè)備的局部壓力損失。對氣流干燥管的熱力學(xué)模擬和實(shí)驗(yàn)研究表明：氣流干燥過程對應(yīng)兩階段干燥動(dòng)力學(xué)模型(two-stage drying kinetics model)中的第一個(gè)階段,也進(jìn)一步證明了氣流干燥過程中的水分蒸發(fā)主要發(fā)生在恒速干燥階段；油頁巖氣流干燥過程中,計(jì)算傳熱系數(shù)的Nu～Re的經(jīng)驗(yàn)關(guān)聯(lián)式為J.Baeyens經(jīng)驗(yàn)關(guān)聯(lián)式：Nu=0.15Rep。用該關(guān)聯(lián)式計(jì)算得到的模擬結(jié)果與實(shí)驗(yàn)結(jié)果的相對誤差如下：氣相出口溫度(℃)的相對誤差為-2.9%；物料最終溫度(℃)的相對誤差為-8.9%；氣相出口濕度的相對誤差為35%；平均傳熱系數(shù)的相對誤差為-2.8%。
[Abstract]:Oil shale, as a kind of "unconventional oil and gas resource", is one of the important alternative energy sources in this century, and has attracted worldwide attention because of its rich reserves. However, because of the developed porosity and high water content of oil shale, In the process of distillation, there are many problems which are not conducive to production. Therefore, the oil shale must be dried and dehydrated before it is pyrolyzed, and the airflow drying process is simple because of its large amount of treatment and simple equipment. The advantages of low investment are widely used in drying treatment. In this paper, a new hydrodynamic simulation technique is used to simulate the flow drying process of oil shale. The detailed distribution and variation trend of various flow fields in the drying process are revealed. At the same time, the physical models in the software are redeveloped through the user-defined user defined functionsfunction in the Fluent software. A model of heat and mass transfer is established, which is more consistent with the process of oil shale airflow drying. While the simulation results are systematically analyzed, pilot experiments under cold state and laboratory experiments in hot state are carried out, and the dynamics of airflow tube is simulated. The simulation results of the thermodynamic simulation of airflow drying process are compared with the experimental results, and the simulation results are in good agreement with the experimental data. It is proved that the reliability of the simulation results and the correctness of the self-built model. The dynamic simulation and experimental study of the airflow drying pipe show that there is no interference and influence between the particles for the rare-phase transport state with very low mass ratio of solid to gas. Therefore, the Euler-Lagrangian algorithm should be used to simulate the motion characteristics of the particles, that is, the discrete phase model in Fluent; the intake mode should be changed to two sides of air intake, or an inverted conical shrinkage hole with a suitable tilt angle should be added to the bottom of the airflow pipe. All of them can obviously improve the phenomenon of bias which is easy to appear in the air intake on one side. However, the shrinkage pore structure also increases the local pressure loss of the equipment. The thermodynamic simulation and experimental study on the airflow drying tube show that the gas drying process corresponds to the first stage of the two-stage drying kinetics model. It is further proved that the evaporation of water in the process of airflow drying mainly takes place in the stage of constant speed drying, while in the process of gas flow drying of oil shale, The empirical correlation formula of Nu~Re for calculating heat transfer coefficient is J. Baeyens empirical correlation formula: 0.15 Rep. the relative error between the simulated and experimental results calculated by this correlation formula is as follows: the relative error of gas phase exit temperature (鈩，

本文編號：1569391