Scale down — scale up of batch—semi batch ops using VisiMix Software

Moshe Bentolila, Sales and Customer Support, VisiMix Software and Roberto Novoa, Sales and Customer Support, VisiMix Software show a method for ‘Scale Down – Scale Up of Batch – Semi Batch’ operations built under hydrodynamics study of the mixing procedure in the reactor system

Chemical production is a result of several chemical reactions and purification steps. Purification steps and processes yield are a direct function of the level of understanding of the reaction system. Reaction quality results have a tremendous impact in separation technology.

Chemical production is frequently performed on stirred vessels that are operated at batch or semi-batch configuration. The choice process configuration is determined at the development stage of the project. Therefore, if the chemical reaction and mixing are not well understood, wrong selections will be adopted in the process development.

Once the process (chemical, biological or physical) is known well, a common situation during the process transfer from lab to production or from site to site is the gap between the old and new results. If the hydrodynamics knowledge is integrated with the chemical phenomena, it will be possible to set up small and automatic equipment to prove the relationship between mixing and chemistry. In this way, it may be the first time that the process will be evaluated at large scale similar conditions. The main advantage of the methodology is the combination of neither realistic conditions in small equipment and of course catching the main normal gaps between the lab and the production results. The combination of equipment and calculation decrease drastically the experiments work required to solve any topic like scale-up or even improve process that running regularly in the large scale. (Bentolila 2011).

The company’s goal is to develop a method, based on calculated parameters that will run properly in the first trial on a new scale or site, similar to the successful results in the lab or in the old facility.

The main parameters changed are the hydrodynamics of the system. If the company is able to identify and control these parameters, it will be able to achieve the available and optimal solution.

Proposed method

Process development at the chemical industry (pharmaceutical, API, food, fine chemicals, biotechnology among others) is performed in small glass reactors. From this lab small glass reactors experience is common to obtain kinetic constants and mixing effects. Akiti [2005] demonstrated the dissimilarity of these reactors since a small glass reactor is not an ideal reactor. Good data for scale up is obtained from the combination of the experimental data with the computation facilities. One of the first authors that thought about this concept was Eng. Berty. In his paper he explained how the computation tools are more developed and the equipment and sensors are more exact. In this way he presented in his paper the follow flow chart, Figure1 and confirmed by Basu [1999] and Ka Ming Ng [2003].

The basic principle (Figure 1) is to collect data from bench scale equipment, exploit the data by designing commercial-scale process configuration (not for construction but for detailed critical analysis) using mathematical and computation knowledge. After few loops of bench scale experiments and design calculations it will be possible to scale up the designed plant to pilot plant facilities and confirm the hybrid model-experimental data at plant facilities conditions. After the last critical step it will be possible to perform fine tuning and design the commercial process.

Typical flow path for process development in companies are presented in the follow flow chart, Figure 2.

In this pathway, a vast disconnection has been found between all the required knowledge to develop the process, including the communication between different departments in the company.

Flow charts for the best organisation of scale up activities were presented for different authors. Normally, all of them wrote in industrial journals. The common factor is to try to intensify the number of experiment requires for achieving a good knowledge of the process. Lastly, the scale-down concept is used in order to characterise the process in small scales.

The main question is how after having a good understanding of the scale-down study, the authors continue to have a gap between lab results, pilot result and production results in the process. A well set up of lab equipment, based on the intrinsic change in the scale up activities will focus the best set of experiments to avoid this gap. Based on the Figure 1, the advised flow chart was despoiled in a completed method that contains the follow steps:

• Chemistry or biological mechanism of the process
• Design the future feasibility according to the business company plan
• Calculate by different simulations tools how will be the process in the commercial scale.
• Set the lab equipment in the possible scale that will provide the most approximate conditions that in the commercial production scale.
• Optimise the process based in the possible range work available in the commercial step
• Use the medium scale to verify your model.

The company considers VisiMix the better simulation tool to estimate hydrodynamics characteristic parameters for batch and semi-batch process. Hence, the proposed method, that take into account upper six steps is like in general view which is shown in Figure 3.

Thus Visimix is not just mixing, but the entire spectrum of mixing related phenomena

Visimix represents the next generation of chemical engineering software. The mathematical models incorporated in Visimix creates a single system which allows for performing several steps of simulation.

VisiMix is chosen one of 2014’s 20 most promising chemical technology solution provider that help customers in the chemical industry to optimise their technology investments and deploy new capabilities.

For more information on VisiMix simulation software please contact Skytech systems Pvt Ltd, Thane at 022 – 41533326 Or Email us at ankur.pandey @skytechindia,com