费托合成搅拌釜气含率的冷模实验与CFD模拟
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摘要
为解决费托合成实验室气-液搅拌釜相分散的问题,冷模实验以轻柴油-空气为工作介质模拟费托合成工况。采用化学刻蚀法制备的光纤探针,考察不同表观气速、搅拌转速及气体分布器结构的搅拌釜内气含率分布。同时,采用双流体模型和标准k-ε湍流模型,对搅拌釜流场进行数值模拟。结果表明:局部气含率随表观气速增大而增大、随搅拌转速增大而增大;改进入口气体分布器对气体均匀分布的作用明显;改变釜体结构可以有效地改善釜底物相分散。
A gas-liquid stirred tank reactor is used as the laboratory device to test the Fischer-Tropsch synthesis catalyst. In the tank the flow field is very complex. It makes a problem that the parallelism of the stirred tank reactor is not satisfactory. The optical fiber probe was prepared by chemical etching, and was used to study the local gas holdup of cold model experiment. The cold model experiment mediums were light diesel oil and air. In all these cases, the influence of superficial gas velocity, stirring speed and gas distributor on local gas holdup were investigated. At the same time, the flow field in the stirred tank was simulated by computational fluid dynamics(CFD), which using two-fluid model along with standard k-ε turbulence model. The results show that the local gas holdup will increase with the superficial gas velocity and stirring speed; the change of inlet gas distributor will obviously improve the uniform distribution of gas; and changing the structure of the gas-liquid stirred tank can effectively improve phase dispersion of the tank bottom.
A gas-liquid stirred tank reactor is used as the laboratory device to test the Fischer-Tropsch synthesis catalyst. In the tank the flow field is very complex. It makes a problem that the parallelism of the stirred tank reactor is not satisfactory. The optical fiber probe was prepared by chemical etching, and was used to study the local gas holdup of cold model experiment. The cold model experiment mediums were light diesel oil and air. In all these cases, the influence of superficial gas velocity, stirring speed and gas distributor on local gas holdup were investigated. At the same time, the flow field in the stirred tank was simulated by computational fluid dynamics(CFD), which using two-fluid model along with standard k-ε turbulence model. The results show that the local gas holdup will increase with the superficial gas velocity and stirring speed; the change of inlet gas distributor will obviously improve the uniform distribution of gas; and changing the structure of the gas-liquid stirred tank can effectively improve phase dispersion of the tank bottom.
引文
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[25]Lane G L,Schwarz M P,Evans G M.Numerical modelling of gas-liquid flow in stirred tanks[J].Chem Eng Sci,2005,60(8):2203-2214.
[26]段晓霞.搅拌槽微观混合的数值模拟研究[D].北京:中国科学院过程工程研究所,2017:79-86.
[27]何洲.搅拌器内部流场特征的数值模拟研究[D].上海华东理工大学,2011:36-38.
[2]温晓东,杨勇,相宏伟,等.费托合成铁基催化剂的设计基础:从理论走向实践[J].中国科学:化学,2017,47(11)1298-1311.
[3]许世峰,王斯民,李彩霞,等.F-T合成浆态床反应器的研究进展[J].化工进展,2013,32(s1):1-5.
[4]Alves S S,Maia C I,Vasconcelos J M T,et al.Bubble size in aerated stirred tanks[J].Chem Eng J,2002,89(1):109-117.
[5]Montante G,Horn D,Paglianti A.Gas-liquid flowand bubble size distribution in stirred tanks[J].Chem Eng Sci,2008,63(8):2107-2118.
[6]李良超,王嘉骏,顾雪萍,等.气液搅拌槽内气泡尺寸与局部气含率的CFD模拟[J].浙江大学学报(工学版)2010,44(12):2396-2400.
[7]Montante G,Paglianti A.Gas hold-up distribution and mixing time in gas-liquid stirred tanks[J].Chem Eng J,2015,279:648-658.
[8]Varela S,Martínez M,Delgado J A,et al.Numerical and experimental modelization of the two-phase mixing in a small scale stirred vessel[J].J Ind Eng Chem,2017,60:286-296.
[9]Lane G L,Schwarz M P,Evans G M.Predicting gas-liquid flow in a mechanically stirred tank[J].Appl Math Modell,2002,26(2):223-235.
[10]Wang W J,Mao Z S.Numerical simulation of gas-liquid flow in a stirred tank with a rushton impeller[J].Chin JChem Eng,2002,10(4):385-395.
[11]Cheng D,Feng X,Yang C,et al.Modelling and experimental investigation of micromixing of single-feed semi-batch precipitation in a liquid-liquid stirred reactor[J].Chem Eng J,2016,293(6):291-301.
[12]Boyer C,Duquenne A M,Wild G.Measuring techniques in gas-liquid and gas-liquid-solid reactors[J].J Cheminf,2003,34(7):3185-3215.
[13]何广湘,郭晓燕,杨索和,等.气液鼓泡床反应器中气泡行为光纤探针测量方法[J].北京航空航天大学学报2017,43(2):253-259.
[14]佟立军.机械搅拌槽挡板的研究[J].有色设备,2005,15(3):17-19.
[15]刘源,王炉钢.六直叶圆盘涡轮搅拌器的流动特性研究[J].化工装备技术,2015,36(6):6-8.
[16]杨修文,祝生祥,胡毅.大锥角光纤探针的制备[J].光学与光电技术,2007,5(5):57-60.
[17]郑荣钏,杨瑞昌,沈幼庭.单纤光纤探针测量空泡份额的实验研究[J].工程热物理学报,1997,18(1):99-102.
[18]宋月兰,高正明,李志鹏.多层新型桨搅拌槽内气-液两相流动的实验与数值模拟[J].过程工程学报,2007,7(1)24-28.
[19]崔巍,朱家文,杨志东,等.多级搅拌塔气液体系的轴向混合和气含率[J].化学反应工程与工艺,2009,25(2)116-120.
[20]高娜,包雨云,高正明.多层桨搅拌槽内气-液两相局部气含率研究[J].高校化学工程学报,2011,25(1):11-17.
[21]Botton R,Cosserat D,Charpentier J C.Operating zone and scale up of mechanically stirred gas-liquid reactors[J].Chem Eng Sci,1980,35(1):82-89.
[22]郝惠娣,朱娜,秦佩,等.单层桨气液搅拌釜的气液分散特性[J].石油化工,2014,43(6):669-674.
[23]Sun H,Mao Z S,Yu G.Experimental and numerical study of gas hold-up in surface aerated stirred tanks[J].Chem Eng Sci,2006,61(12):4098-4110.
[24]孙姣,崔绍华,孙泽沾,等.不同挡板絮凝反应器流场的实验研究[J].化工进展,2012,31(8):1700-1706.
[25]Lane G L,Schwarz M P,Evans G M.Numerical modelling of gas-liquid flow in stirred tanks[J].Chem Eng Sci,2005,60(8):2203-2214.
[26]段晓霞.搅拌槽微观混合的数值模拟研究[D].北京:中国科学院过程工程研究所,2017:79-86.
[27]何洲.搅拌器内部流场特征的数值模拟研究[D].上海华东理工大学,2011:36-38.