Mixing Parameters for Successful Scale-Up: Key Lessons for Engineers

The process that is required to transfer our project from lab to the production scale is controlled by the interaction between the materials that we have in our tank. This interaction between the materials is controlled by the environment we are providing them to interact in. Different kinds of equipment and different kinds of flow direction and energies will generate completely different kinds of interaction between the materials. 

So, the mixing function and role in this process to transfer our process from lab to the production scale is directly affected by the environment we are providing to our materials to interact between them, progress in the process, and generate the product that we are looking for. 

The Multi-Dimensional Nature of Mixing

Because mixing is a multi-dimensional phenomenon, we need to take into consideration multi-variables simultaneously. We must look at variables that are describing the local mixing, as well as the interaction between the fluid elements and the molecules we have in the tank. Different zones in the tank will have different energies and different capabilities to generate connections between fluid elements. As engineers, we need to provide the power and direction of the flow that will be good enough to generate the exact result that we are looking for. 

When the process is a reaction, a crystallization, an emulsification, a formulation, or a fermentation, different kinds of mixing parameters will influence the process, depending heavily on the specific process itself: 

• Processes Controlled by Molecular Interaction: If the process is more controlled by the interaction between the molecules, we are talking about local mixing. In these cases, the micro mixing time and the eddy size will be the main important parameters to evaluate. 
• Processes Controlled by Blending and Formulation: When we talk about blending or formulation, and the level of this formulation is about the order of magnitude or 99% of homogeneity, we're talking about macro mixing time. In this scenario, we are talking about flow, circulation flow into the tank, heat release, and how to take the heat release from the tank to fix the temperature and the temperature required for the process. 

The Main Important Lesson for Every Engineer

If we talk about what is the main important lesson for every engineer, it is to understand that the mixing is the tool we need to provide the conditions that will be good for my process. 

What is good for my process? It means generating an acceptable purity, achieving as high as possible productivity, and completely avoiding problems in the operation. This means avoiding critical operational problems such as: 

• Foaming at the surface of the liquid phase. 
• Plugging the bottom of the tank with solids due to materials being poorly distributed. 
• Having no capability to release the heat from the tank and from the process, which disrupts temperature control. 

The key lesson is to understand that mixing is the tool, and it is the main and only reason that because of the change of the size of the equipment, we will have deviations in quality, purity, and operation. This happens because we are normally keeping the procedure and the quality of the raw materials completely fixed at this distance and at this step. We normally succeed in the laboratory step, because if we didn't succeed there, we would not go to the next scale-up step in the first place. Attempting scale-up without evaluating these shifts is dangerous, and the risk to the operation is incredibly high.

Managing Your Scale-Up for Total Success

The point is that when we know what are the mixing parameters that are controlling the process in all the levels, and we truly understand the influence of these parameters in different kinds of processes, we will be able to manage our scale-up in a way that will be completely successful. 

What is a successful scale-up? It will provide me enough knowledge about what is the range of work of mixing that will be good at any step, at any equipment, and in any scenario that we will have in the company. This operational knowledge becomes vital because we are frequently transferring the process to other sites where the geometries and the agitators are completely different, or we are managing the process in the same plant with other equipment, even if it is with the same size vessel. 

Once we know what is the pure hydrodynamic and what is required for the chemical system, we will try to find this exact hydrodynamics in different pieces of equipment. Of course, it is true that not in all equipment will we be able to generate the exact conditions that are required. However, by utilizing mathematical tools, it will be good enough to know how to detect maybe a safe zone of operation that will be possible and will generate acceptable results for the plant. 

Ultimately, by understanding these parameters, we will be able not only to do the scale-up successfully, but also to design our equipment. In this way, we are able to design exactly what is required because we know what is the flow, and we come with the background of the chemical affinity of the material that is required to progress with the process in a good way. 

Optimize Your Chemical Systems

Don't let changing tank geometries introduce unneeded risks to your product's purity and operation. Learn more about fluid behaviors by reviewing our guide on What are the processes of mixing? or explore how our Industrial Process Simulation Software accurately maps out local mixing energies. You can also review specific mathematical tools optimized for your media viscosity, such as VisiMix Turbulent and VisiMix Laminar.

Ready to see how VisiMix calculates macro and micro mixing parameters for your specific equipment? We invite you to download our free demo today and start calculating the exact hydrodynamics your process needs to succeed.