VisiMix Case Study – Increased Productivity

One of the most important activities for any company that wants to improve day-to-day operations is to increase process productivity. In the chemical industry, many of the processes we deal with are two-phase batch reactions, where one reagent is solid and the second reagent is dissolved in a solvent.

A typical question regarding efficiency in these reactions is how to reduce the operation time in order to increase productivity. If we want to improve production from 1 kg to 2 kg per hour (or per year, etc.), we need to make better use of the volume of the equipment and reduce the time that the reaction or process takes, to manufacture more material over the same period.

One of the companies we have worked with for many years came to us with concerns about their production time. When transferring their process from the lab to the production line, the reaction time increased from around 9 hours to roughly 50 hours. Although the process took a longer time, the operation and product purity remained satisfactory. The company wanted to understand why the reaction time increased so significantly when moving from the lab to production and figure out how to reduce that time. The main question we needed to answer was whether this increase in reaction time was a result of the kinetics of the reaction, or if it was related to the equipment being used.

In this case, the operation was evaluated using VisiMix. The reactor was 25 liters, but the volume used to run the first step of the reaction was only around 10 liters. Through observation of the production and our calculations, we immediately noticed that the vortex depth was greater in production than in the lab, and a layer of solids was forming around the level of the vortex. The vortex was not stable, instead moving up and down, up and down—this type of operation can generate the thin film of solids that was seen on top. The solid was one of the reagents, and the resulting difficulty in incorporating all the solids into the liquid phase led to the long time it was taking to complete the reaction.

The reason for the deep vortex in the production equipment was very clear in our analysis. In the production equipment, only one buffer was used, while complete buffer equipment was used in the lab. We immediately saw that we needed to add another two buffers in production to generate the same hydrodynamics that existed in the lab.

Despite the results of our analysis, management did not accept our recommendation. But for reasons that were perhaps destiny or at least beyond our control, a 25-liter glass equipment used in production broke, giving us another opportunity to once again recommend that another two buffers be added to reduce production time. After purchasing the equipment with three buffers, the reaction time fell from 50 hours to 9 hours. So, this simple modification that was not initially taken into consideration generated an improved reaction time, saving approximately $1.6 million per year. Thanks to the increased manufacturing capacity and a strong market for the popular material, we were able to increase sales. And all of these problems really in the point of view of people that work in simulation and wanting to give a recommendation, it took us not more than one week. So, we calculate, we did it with the understanding of what happened here in two weeks. It’s really important to consider that.

You might ask, “Why didn’t management accept the recommendation? Why wasn’t it taken into consideration?” The answer is simple. Understanding the influence of the mixing process on the reaction time is not so trivial. In our everyday lives, we are always mixing in our kitchens, making cookies or cake, or even stirring our coffee without thinking about it. We assume that mixing is always consistent and successful, but might think, “I don’t know why the cake today was not the same as yesterday or the day before that, even if I used the same ingredients.” Or we might wonder why our coffee is a little different. And that’s the reason.

Mixing is an incredibly important unit operation that we need to understand is happening anyway. It serves as the basis for converting the raw materials into the results we are trying to generate. So, if we know which mixing parameters are important within the production process, we can optimize the reaction and provide the company with the results it is looking for. Because we are working in this field in the company; process chemical engineers and process development people are in charge of answering the question, what will happen with my process in the next step?

Like in this case study, we’ll always share our recommendations with you, emphasizing what needs to be done from a mixing standpoint to ensure that expected productivity and quality will be achieved and that no safety problems will occur in operation.

VisiMix Video

The Influence of Mixing in the Process
New methodology using VisiMix software for the purpose of checking the influence of mixing in the processes.

VisiMix Demo Operation
Learning how to input data into the VisiMix software and get results the will help us understand the influence of mixing in our processes.

Lab Experiments
Learning how to set up the relevant experiments at the lab scale, to develop the processes from an engineering point of view.