Experimental Investigations and Modeling of Internal Mixing Effects in Reaction Mixing Pumps
Creators: name: Mayer, Yannick
name: Eberweiser, Simon
name: Bey, Oliver
name: Ashrafmansouri, Seyedeh-Saba
name: von Harbou, Erik
Publisher: name: Zenodo
Year: 2024
Subjects: reaction mixing pump
side channel pump
peripheral pump
fluid dynamical model
mixing
reaction engineering
chemical reactor
multi phase reaction

description: Stirred tank reactors are widely used in various chemical processes due to their mixing properties, which increase mass and heat transfer inside the vessel. Hence their mixing properties these reactors facilitate reactions in multi-phase fluid systems which are widely used in the chemical industry. However, the mixing efficiency of those reactor types is limited by their specific power input typically ranging from 0.1 to 10 W/kg [1].Side channel and peripheral pumps can present a promising alternative to stirred tank reactors. Due to the design of the pumps, only a small fraction of the power input contributes to convey the fluid and to increase the pressure, while the majority of the power input is utilized to generate high internal circulation and thus is dissipated which leads to the overall low pump efficiency [2]. Compared to stirred tank reactors the specific (dissipated) power input is much higher and can reach values of more than 10.000 W/kg. For this reason, these pumps are in principal well suited as reactors for mixing sensitive reactions. This type of reaction occurs when the reaction rates are very fast and the rate of conversion is limited by mixing of the reactants or mass transfer between different phases. Despite the potential benefits of these so-called reaction mixing pumps (RMP), there has been limited research conducted on this specific type of reactor. To use RMPs as chemical reactors, their behavior in terms of conversion, yield and selectivity must be predictable. The internal flows in the RMP are an important factor affecting the behavior of the RMP as a reactor. They determine the time required to dilute the feeds to the composition of the reaction mixture (also known as micromixing) and, in the case of multiphasesystems, the mass transfer between phases. They also directly influence the internal macroscopic concentration profiles within the pump (macromixing). 

These variables in turn determine the local reaction rates. Therefore, we developed a 1D fluid dynamic model of the RMP that describes the internal flows. The model is based on the conservation of angular momentum. This fluid dynamic model, however, requires parameters that describe the friction losses in the pump. These friction parameters are usually initially unknown. In our poster we will show that these parameters can be well estimated from the pump’s characteristic curves. We applied this approach to two different RMPs. Using the parameterized fluid dynamic models, we were able to describe the internal flows in the RMP, in particular, the flow in the side channel and the circulation between the side channel and the impeller channel. These two values characterize the internal cross- and backmixing in the RMP and provide valuable information on howthe RMP behaves as a reactor.

References:[1] Güttel, R., Turek, T., Chemische Reaktionstechnik, 2021[2] Grabow, G., Forschung im Ingenieurwesen, 2002, 67,100-106.