基于介尺度PBM模型的生物反应器放大模拟及实验研究

doi:10.11949/0438-1157.20220089

摘要/Abstract

摘要：

对于通气搅拌式工业生物反应器的放大设计而言，精确预测气泡尺寸和体积传质系数非常重要，因此需要建立合适的气泡聚并和破碎模型，以保证反应器的高效操作。以5 L通气搅拌式生物反应器为对象，以气泡尺寸和体积传质系数的实验数据为基准，模拟并考察了两种聚并模型和四种破碎模型对生物反应器内流体流动行为以及传质能力的影响。结果表明，基于介尺度理论的修正聚并模型与考虑黏流剪切的破碎模型组合，所得模拟结果与实验数据吻合最好，这为大型生物反应器的桨型优化提供了模型基础。因为工业化生物发酵通常是在大型生物反应器中进行，搅拌桨型对生物反应器效能至关重要，故本研究在选定最优气泡聚并破碎模型的基础上，通过叶轮末端剪切力相等的放大原则将5 L通气搅拌式工业生物反应器放大到400 m³，同时考察了六斜叶圆盘搅拌桨、非对称式抛物线搅拌桨、布鲁马金式搅拌桨以及六直叶圆盘搅拌桨等桨型组合对气泡破碎能力和气体分散效果的影响，并通过综合对比气含率、体积传质系数等参数，得到400 m³通气搅拌式生物反应器的最优桨型组合。

关键词: 生物反应器, 计算流体力学, 放大设计, 聚并模型, 破碎模型, 优化设计

Abstract:

Accurate prediction of bubble size and volumetric mass transfer coefficient is very important for the scale-up design of aerated-stirred industrial bioreactors, and thus it is necessary to establish a suitable bubble coalescence and breakup model to ensure the efficient operation of the reactor. In this work, taking a 5 L aerated agitated bioreactor as a sample, and based on experimental data of bubble size and volumetric mass transfer coefficient, the effects of two coalescence models and five breakup models on the simulated flow behavior and mass transfer capacity were investigated. The results show that the combined simulation results of the modified coalescence model proposed based on the mesoscale and the breakup model considering viscous shear are in the best agreement with the experimental data, this provides a model basis for the paddle type optimization of large bioreactors. Because industrial bio-fermentation is usually carried out in large bioreactors, where the stirring paddle type is crucial to the bioreactor efficiency, this paper enlarges the 5 L aerated stirred industrial bioreactor to 400 m³ by the principle of equal terminal shearing force of the impeller on the basis of the optimal bubble aggregation and fragmentation model, and the influence of the combination of six-vertical-leaf disk turbine impellers, asymmetric parabolic impellers, Blumarkin impellers and six straight-blade disk turbine impellers on the bubble breaking capacity and gas dispersion effect were discussed. The optimal model combination is further used to optimize the stirring paddle type of a 400 m³ large-scale industrial bioreactor, meanwhile, the optimal combination of 400 m³ aeration-stirred bioreactor is obtained by comprehensively comparing multiple parameters such as gas holdup and volumetric mass transfer coefficient.

Key words: bioreactors, computational fluid dynamics, scale-up design, coalescence model, breakup model, optimal design

中图分类号:

TQ 021.4

万景, 张霖, 樊亚超, 刘勰民, 骆培成, 张锋, 张志炳. 基于介尺度PBM模型的生物反应器放大模拟及实验研究[J]. 化工学报, 2022, 73(6): 2698-2707.

Jing WAN, Lin ZHANG, Yachao FAN, Xiemin LIU, Peicheng LUO, Feng ZHANG, Zhibing ZHANG. Bioreactor scale-up simulation and experimental study based on mesoscale PBM model[J]. CIESC Journal, 2022, 73(6): 2698-2707.

图/表 12

图1 生物反应器实验装置

Fig.1 Bioreactor experimental setup

表1 本文研究的聚并模型详细信息

Table 1 Details of the coalescence model studied in this paper

聚并模型简称	聚并模型
C1	Luo
C2	M_c-Luo

表2 本文研究的破碎模型详细信息

Table 2 Details of the crushing model studied in this paper

破碎模型简称	碰撞频率
B1	ω₁
B2	ω₂+ω₃
B3	ω₂+ω₄
B4	ω₅

图2 网格数量对模拟kLa和d32的影响

Fig.2 Effects of mesh number on simulated kLa and d32

图3 0、200、300、400 r/min的气泡图(a); 不同模型不同转速下的平均直径(b)

Fig.3 Bubble diagrams at 0, 200, 300, and 400 r/min (a); Mean diameter of different models at different speeds (b)

图4 最优模型组合下不同转速的气泡直径分布

Fig.4 Distribution of bubble diameters at different rotational speeds under the optimal model combination

图5 DO值随时间的变化曲线(a)和拟合曲线(b)，不同模型组合在不同转速下的kLa(c)

Fig.5 Variation curve (a) and fitting curve (b) of DO value with time， kLa of different model combinations at different speeds (c)

表3 不同实验次数下kLa随转速的变化情况

Table 3 kLa changes with speed under different number of tests

试验次数	传质系数k_La
试验次数	200 r/min	300 r/min	400 r/min
第一次	0.0155	0.0242	0.0384
第二次	0.0153	0.0237	0.0378
第三次	0.0158	0.0244	0.0387

图6 最优模型组合下不同转速的体积传质系数分布

Fig. 6 Distribution of volumetric mass transfer coefficients at different rotational speeds under the optimal model combination

图7 400 m3生物反应器桨型组合

Fig.7 400 m3 bioreactor paddle type combination

图8 400 m3生物反应器不同桨型气含率分布

Fig.8 Distribution of gas holdup with different paddle types in a 400 m3 bioreactor

图9 400 m3生物反应器kLa分布

Fig.9 kLa distribution of 400 m3 bioreactor

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