Chemical process calculations

Paradigm Shifts

Process intensification is a paradigm shift in the chemical engineering industry, as it means that we can begin to look at chemical processing not from the point of view of incremental improvement, instead from the point of view of transformative improvement.  These are built around the principle of doing things in a single modular unit where everything is built on one platform.  It is a change in the way we think of the process as a completely integrated one from raw material to final product instead of sequential steps.  This enables us to think about things in a broader context.

Why did we not do this before?

Actually, we were doing parts of the process before, but what stopped us was the technology.  In the last couple of decades there have been a number of enabling technologies that have allowed this change to happen, such as, things like being able to meter materials at very small volumes, enhanced process control and additive manufacturing.  These are all enabling technological advances that allow us to think about process improvement today in a different way than we could in the past. 

So what would that mean for our process? 

Well, instead of using large seven-foot diameter type vessels, we could use and process multiple smaller vessels.  One of the advantages of much smaller vessels is that they can each be designed to be customized for a particular process step. Each of those vessels can be optimized for the process conditions of that process step, which means things such as temperature, the intensity of the mixing, running it under pressure, running it with recirculation, etc.  Therefore, rather than having one single large vessel that is tied up for a long period of time, you can have these three very small vessels and would equal or exceed the same volume. Typically, they would be on a single platform that you could move around with ease.

What this means is that industrial setting economics dictate everything: the major considerations for system design, the vessel size, the impeller design, the size of motor, shaft design and gearbox, which were mentioned before.  If we applied the concepts of process intensification, using a continuous multiple vessel system and similar assumptions, the net present value would increase by a factor of 10.  In addition to this, the capital investment in the continuous system would be about 30 percent less than when using the larger semi-reactor.   Therefore, you can reach a much higher production volume at a much lower cost. Furthermore, you can reduce the heating and cooling time, which are common with batch operations.

In Conclusion

Dynamic viscosity changes are quite difficult to model and are most certainly very difficult to model in a continuous computation.  Therefore, what needs to be done is a discrete approach, which is basically to provide guidance in the design (from a design point of view, a small vessel is much easier to handle) and selection of equipment.

Certainly, understanding the system rheology is important for interpreting the models. VisiMix gives you the ability to answer the question of what is the best way to design your system – both for higher viscosity worst cases or the low viscosity cases.

VisiMix leverages a short training time and focuses on results.  It really helps inexperienced users to circumnavigate the typical programming challenges, as when using other simulation program, it becomes a substantial part of the problem rather than the solution.  VisiMix allows facilities to focus on novel processing, using process intensification concepts. VisiMix allows fast learning, really quick screening and guidance to the less experienced engineers.

This is how you generate value in industrial setting.

How could VisiMix help a new engineer?

When you encounter different kinds of problems, the first thing you usually do is grab a book, and look up the correlations, then grab a slide or calculator and actually do those calculations by hand, which would typically take a fair amount of time, especially if you did don’t do them regularly – Now you can play with the data directly in VisiMix.
Chemical process calculations
How Can VisiMix help with gas liquid mixing problems?

It is a little difficult to gauge the accuracy of the results for gas liquid mixing because you typically do not have any real data in the industrial sector, but our clients have given us feedback and reported to us that they are getting quick directional solutions.  For example, one of our clients had a specific problem where they had a new system that they were starting up with very large 50,000 gallon reactors. It turned out that the design of the mix of the system, which was done by one of the major suppliers, was not the correct design because the information given to them on the system was not accurate. So VisiMix actually helped in improving the operation of an existing system. It turned out that the solution was to increase the flow of nitrogen through a purge ring.

This article is based on Cliff Kowall lecture on VisiMix Forum. 

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.