本文選題：MTO + 放大��； 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)》2017年碩士論文

【摘要】：新興的甲醇制烯烴(MTO)工藝可實現(xiàn)甲醇到低碳烯烴的轉(zhuǎn)化過程。因為甲醇可方便地從煤和天然氣中獲得,因此MTO工藝架起了煤化工和石油化工之間的橋梁,有望在不久的將來成為生成低碳烯烴的主要路線。目前,MTO工藝已實現(xiàn)商業(yè)化運行,而相關(guān)的化學(xué)反應(yīng)工程的基礎(chǔ)研究很少報道,特別是反應(yīng)器的放大仍然依賴于經(jīng)驗和逐級放大實驗,缺乏可靠的理論指導(dǎo)。傳統(tǒng)的反應(yīng)器放大準(zhǔn)則主要關(guān)注放大過程中的流動參數(shù)的相似性,而忽略了流動和反應(yīng)的雙向耦合,因此無法有效指導(dǎo)實際放大過程。近年來,隨著計算流體力學(xué)(CFD)技術(shù)和多相流理論的迅速發(fā)展,特別是介尺度理論的興起,采用CFD模擬研究反應(yīng)器的放大過程將有助于深刻理解反應(yīng)器中流動和反應(yīng)及其耦合行為隨著反應(yīng)器放大的變化規(guī)律,有望縮短傳統(tǒng)的基于實驗的反應(yīng)器放大進程。然而,反應(yīng)器的放大勢必涉及操作流域的一系列改變(如從鼓泡流域到湍動流域的變化)以及隨之帶來的對停留時間、反應(yīng)行為等的影響,這給CFD模擬帶來新的挑戰(zhàn):1)反應(yīng)器放大過程中涉及流域轉(zhuǎn)變,不同流域存在不同的流動結(jié)構(gòu),如鼓泡床中的"氣泡"和快速床中的"顆粒團聚物",在不同流域中選擇合適的曳力本構(gòu)關(guān)系是個非常關(guān)鍵的問題;2)受限于計算量,在CFD模擬中,一般采用集總模型描述反應(yīng)動力學(xué)。而集總反應(yīng)動力學(xué)模型通�；谛⌒土骰矊嶒�,過濾了外部流場變化帶來的影響,它是否適用于操作在不同流域的大規(guī)模反應(yīng)器的模擬需要深入探索和驗證;3)工業(yè)MTO反應(yīng)器尺寸大且顆粒停留時間長,Lu等[1]人提出的全混流(CSTR)模型用作CFD模擬的初值預(yù)測從而加速反應(yīng)模擬的方式是否也適用于工業(yè)反應(yīng)器的加速模擬,還需進一步研究。針對上述挑戰(zhàn),本文圍繞MTO反應(yīng)器的放大過程開展了一系列研究。論文第一章介紹MTO工藝的發(fā)展現(xiàn)狀、工藝特點、各種模擬方法、以及已開展的模擬工作。在此基礎(chǔ)上,引出本文的研究內(nèi)容。論文第二章以大連化學(xué)物理研究所開發(fā)的MTO工藝(DMTO)的放大過程為切入點,開展不同尺度的DMTO反應(yīng)器的放大模擬研究。其中,流動模型采用雙流體模型(TFM),曳力模型根據(jù)不同反應(yīng)器的操作狀態(tài)(如鼓泡和湍動狀態(tài)),分別采用了 EMMS/bubbling模型和最新開發(fā)的二步法模型,反應(yīng)動力學(xué)采用了平行反應(yīng)的七集總模型。在此基礎(chǔ)上,分析了流動和反應(yīng)行為隨著反應(yīng)器放大的變化情況,進一步考察了反應(yīng)動力學(xué)模型對模擬結(jié)果的影響。研究表明,上述模擬方法可準(zhǔn)確預(yù)測不同尺度反應(yīng)器內(nèi)的流場分布和甲醇轉(zhuǎn)化率,但對主要產(chǎn)物(乙烯和丙烯)的預(yù)測,則隨著反應(yīng)器的放大而逐漸偏離實驗�？紤]產(chǎn)物轉(zhuǎn)化反應(yīng)的交叉動力學(xué)模型代替平行反應(yīng)模型,依然無法改善對反應(yīng)產(chǎn)物的預(yù)測。由于產(chǎn)物的選擇性與催化劑的焦炭含量密切相關(guān),而基于TFM的模擬無法區(qū)分同一固相中的顆粒差異,從而不足以準(zhǔn)確預(yù)測催化劑顆粒的焦炭含量分布。為在模擬中考慮焦炭含量分布的影響,論文第三章提出采用群體平衡模型(PBM)來描述由焦炭含量確定的催化劑顆粒分布情況。先由全混流反應(yīng)器模型估算顆粒停留時間分布,結(jié)合焦炭的生成速率方程,計算得到焦炭含量分布,作為TFM耦合PBM模擬的初始值,采用離散法求解PBM中的焦炭含量的分布密度函數(shù)。在此基礎(chǔ)上,對DMTO示范反應(yīng)器進行了二維模擬。研究表明,上述方法能夠有效地預(yù)測焦炭含量分布,顯著提高模擬對主要產(chǎn)物選擇性的預(yù)測。論文最后對全文進行了總結(jié),并對未來如何完善流化床反應(yīng)器的放大模擬工作進行了展望。
[Abstract]:The new methanol to olefin (MTO) process can realize the conversion process of methanol to low carbon olefin. Because methanol can be easily obtained from coal and natural gas, the MTO process has erected a bridge between coal chemical and petrochemical industry. It is expected to become the main route of producing low carbon olefin in the near future. At present, the MTO process has been commercialized. The basic research of the related chemical reaction engineering is rarely reported. Especially, the amplification of the reactor is still dependent on the experience and the step by step amplification experiment and lack of reliable theoretical guidance. The traditional reactor amplification criterion mainly focuses on the similarity of the flow parameters in the amplification process, but neglects the two-way coupling of the flow and reaction, so there is no one. In recent years, with the rapid development of the computational fluid dynamics (CFD) and multiphase flow theory, especially the rise of the mesoscale theory, the CFD simulation of the amplification process of the reactor will help to understand the flow and reaction in the reactor and its coupling behavior with the amplification of the reactor in recent years. It is expected to shorten the traditional experiment based reactor amplification process. However, the amplification of the reactor is bound to involve a series of changes in the operation of the basin, such as the change from the bubbling basin to the turbulent River Basin, and the consequent effects on the residence time, reaction behavior, etc. this brings new challenges to the CFD model: 1) the amplification process of the reactor involves the amplification process of the reactor. There are different flow structures in different basins, such as "bubbles" in bubbling beds and "particle aggregation" in fast beds. Choosing appropriate drag constitutive relations in different basins is a key problem; 2) limited to the amount of calculation, in CFD simulation, the lumped model is generally used to describe the reaction dynamics. The model is usually based on the small fluidized bed experiment, filtering the influence of the change of the external flow field. Whether it is suitable for the simulation of large-scale reactor operating in different basins needs deep exploration and verification; 3) the size of the industrial MTO reactor and the long time of the particle residence, the Lu and other [1] people's total mixed flow (CSTR) model are used as the initial of the CFD simulation. For the above challenge, a series of studies have been carried out on the amplification process of the MTO reactor. The first chapter introduces the development of the MTO process, the process characteristics, the various simulation methods, and the simulation that has been carried out. On the basis of this, the second chapter in the second chapter takes the amplification process of the MTO process (DMTO) developed by Dalian Institute of Chemical Physics as the breakthrough point to carry out the magnification simulation study of the different scales of the DMTO reactor. Such as bubble and turbulent state, the EMMS/bubbling model and the newly developed two step model were used respectively, and the reaction kinetics adopted the seven lumped model of parallel reaction. On this basis, the effect of the flow and reaction behavior with the change of reactor magnification was analyzed, and the effect of the reaction kinetic model on the simulation results was further examined. The results show that the simulation method can accurately predict the flow field distribution and the conversion rate of methanol in different scale reactors, but the prediction of the main products (ethylene and propylene) is gradually deviated from the experiment with the amplification of the reactor. Because the selectivity of the product is closely related to the coke content of the catalyst, the TFM based simulation can not distinguish the particle difference in the same solid phase, so that the coke content distribution of the catalyst particles is not accurately predicted. In order to consider the influence of the coke content distribution in the simulation, the third chapter of the paper proposes the use of the group equilibrium model. Type (PBM) is used to describe the distribution of catalyst particles determined by coke content. The distribution of particle residence time is estimated by the model of total mixed flow reactor, and the distribution of coke content is calculated with the formation rate equation of coke. As the initial value of TFM coupling PBM simulation, the distribution density function of coke content in PBM is solved by dispersion method. On this basis, the two dimensional simulation of the DMTO model reactor has been carried out. The study shows that the above method can effectively predict the distribution of coke content and significantly improve the prediction of the selectivity of the main products. Finally, the paper is summarized and the future improvement of the amplification and Simulation of the fluidized bed reactor is prospected.
【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ221.21;TQ018

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本文編號：1960157