There is a fundamental difference between the mixing of chemicals and the mixing process. The mixing of chemicals refers to the selection of chemicals we want to use in order to generate a desired end product. Indeed, our final product depends on the physical properties of the final material, the starting materials that we’re using, and the chemical or physical connection between them. in the manufacturing of creams, lotions, and many other final products that are in liquid phase.

When we’re talking about mixing simulation, we’re talking about how the mixing operation needs to be applied to our materials and the ideal conditions needed to achieve an excellent interaction.

To provide the ideal conditions, we must consider the potential properties of the input and resultant materials.
Mixing simulation addresses conditions such as hemodynamics, mixing parameters, shear rate, the energy of dissipation, and the many mixing parameters related to flow dynamics. If the materials are not compatible, then they will not generate the formulation, Hence, the selection of materials comes from your company’s knowledge regarding each of the materials you are using, why you’re using these materials, and their added value in the formulation. Now you are able to achieve the best environment to realize the potential interaction between the compatible materials that you are using.

So, take care on this very thin and important difference, where you know the compatibility between materials, and we know the environment we need to provide to the materials to manifest the interaction in a good way.

Element Mixer Simulator

By consequence of the questions people ask about how we can simulate chemical reactions, we
have an excellent question about mixing that everyone in the industry is asking. When I meet
professional people in the industry and discuss the sophisticated unit operation of mixing in the
industry, the question that eventually arises is, What is the best way to mix chemicals? Or, what
is the optimal number of mixings for chemicals in the process? The answer that I provide is that
we don’t know; we never know. And the reason we never know is that mixing is not in itself
something that we can generate some generic answers about.

Mixing is a tool. We use mixing to manufacture materials. So, our goal in the industry is to
manufacture materials. When we manufacture materials, we put some of them in a vessel and
we start to steer them under some conditions that we find in the laboratory or in previous
studies in literature. And we need to succeed. What is success when it comes to these
activities? It’s being able to generate a material, a product that will be of good quality and
doesn’t have problems in operation. It’s being able to generate a level of productivity that will
be good enough that the product of this process generates money for the company.
So, this mindset gives us the best way to mix chemicals. Now, it is opposite our normal thinking
because when we think about mixing, the ingrained idea we usually have is that mixing is high
homogeneity, high shear rate, fast velocity. And all of this is true when the mixing is the goal. If
my goal is to have mixing, to understand the mixing, then all the aforementioned criteria are
okay. But when we go to the industry, our main goal is the process, the product, and the mixing
becomes only a tool, a very important tool. The tool should be adapted to the process. So, we
need to provide the process, the environment that is required to generate a good process,
meaning of fit, good productivity, no problems in operation, and acceptable quality according
to the specifications for every step.

So, when we talk about what is the best way to mix chemicals, we need to disconnect between
good mixing and a good process; they are not similar. Good mixing is the capability to generate
the conditions to have a good process. This is described by the purity quality in operation, and
not only with homogeneity, high shear rate, and velocity. Now, once we have achieved this
disconnection between good mixing and process, we will discover that sometimes, when we try to solve our problems by increasing the mixing, we generate worse results. Why? Because we
did not have in mind the concept that when we accelerate the mixing, we accelerate the
malfunction for our process. And we have many examples of this. For instance, a company may
increase the velocity, and as a function of this increased velocity, the distribution of one of the
materials may get better in the tank. But because it gets better, the company may accelerate a
secondary reaction or secondary phenomenon that reduces the quality of the material and put
it outside of the spec. Only when we see good mixing and a good process as separate entities
can we understand that we need to reduce velocity and reduce homogeneity. Otherwise, we
may end up in the situation with the accelerated mixing and the secondary phenomenon that
generates the impurities or the site reaction. The mindset we need is exactly the opposite of
what we have deeply ingrained in our minds.

Once we discard the old mindset, we start to discover solutions we’d never thought of before.
We recognize that high-velocity homogeneity may not be the best process. High-velocity
homogeneity may describe the mixing well, but when the mixing is not the goal and only the
tool, our goal should be the process. And even if the mixing is non-homogeneous and not high
velocity, it’s generating a better result for the process, and this view is what we should adopt.
So, in conclusion, what is the best way to mix chemicals? In the industry, the answer is to
establish the conditions needed to generate good quality according to the specification of the
product at every step, in order to ensure good productivity and avoid problems in the
operation.

Typical questions coming from chemical mixing simulation

what is required in chemical mixing simulation?

So, if we have a simulation package that are doing mass balance and energy balance. If we have a package of software that are doing simulation of different kinds of unit operations by collecting the empirical correlations that are known in the chemical engineering and by solving the mass balance and energy balance in different kinds of operations, why do we need this kind of simulation? We are covering all well from the typical packets are in the market. And the answer is that, all the packets that we mentioned are taking in consideration in one hand, that hydrodynamics is not a function. So, we will have no deviation because we have different kinds of mixing into the tank, like all the solutions coming from the mass balance and heat balance in the equipment, these kinds of software are not taking into consideration the deviation we can get because the hydrodynamic is different into in the tank and of course, generate different interactions between the materials that will generate different results in quality operation and productivity. And on the other hand, if we use packages that are solving by correlations. Normally the correlations are very thin, so the scope of work and the range of work that these kinds of correlation are valid, normally are not fitting our real equipment. And we continue to get deviations, and we are not well using the fundamentals of integral consideration of chemical mechanism hydrodynamic and physical environment by mixing that we need to take in consideration in order to progress to get realistic results.

So, the chemical mixing simulation is required because it is part, a very critical part of our capabilities to provide the process, the environment that will be good for the process to progress and generate the result that we are expecting to have. So, this is the reason that we need chemical mixing simulation as a critical part of the knowledge of the process. It is like we are not taking into consideration part of the knowledge required to progress. So, this is possible, we’re calculating it with a very deep knowledge about the physical phenomena that happened into the tank that will influence directly the results in quality, purity and operation of the result of the process in my equipment.

Is there commercial software for chemical reaction in flow dynamic environment?

Yes, there are many software that you can find; 99% of them are based on computational fluid dynamics, that is the solution of the differential equation of the momentum balance of the flow, by finite elements. It is very known, it’s very popular, it’s very known in the Academy. Students are studying this kind of solutions. The problem is that the solutions are very very theoretical, they are not taking consideration the phenomena that happen into the specific equipment like sterile vessel, and by consequence of it, the results are very very pure in comparison to a real life, and they are not catching the typical problems or performance that the mixing is happening into the tank.

In order to solve this gap between the theory and the practical life, we have VisiMix. VisiMix is a software that is a semi-empirical software. In one hand, it will solve the momentum balance to know the velocity of the flow. In the second hand, in order to be representative and relevant, we have correlations that are taking in consideration the very deeply scientific part of the flow dynamics into sterile vessels, we are calculating the flow generated by different kinds of equipments, and we generate a complete model and theory that are helping us to include it into the momentum balance and to solve the momentum balance to know the velocity of the flow into the tank. And this is the base of any mixing calculation and any flow calculation.

So, if you want to know what is the energy of dissipation, power per volume, shear rate, mixing times, when we calculate in VisiMix, we get these results that are the base of the mixing into tank, but this way, it will change the mass transfer, the mass transfer coefficient, the heat transfer coefficient, the bubble size, the solid distribution, the real rate of reaction, any normal parameter that we assume pure mixing or only theory, we will get result, but they’re very far from the realistic result that we get into a tank, and for this we need to generate some kind of connection between the real life of the equipment that we get with our correlation and how to include in the general model of momentum balance in different levels.

So, VisiMix this is doing it, not only in the flow, even if the unit operations are more than this, the new release, we’re talking about what is the direct influence of the mixing in today’s reaction results, when we take in consideration equipment that is perfect mixing equipment, so the maximum capability of mixing we can get into the equipment in the realistic point of view, and when we are taking in consideration more than these, are realistic equipment.

So, the meaning of this, what happens when we are not taking into consideration that molecules are in from one to the other one, because we have a maximum level of a fluid elements that below the size is not possible to reach, because it is a physical life lag. We are not able to mix molecules, we’re not able to mix fluid elements that will have a minimum quantity of material into these fluids elements that are interacting. So, when we are including this limitation into our reaction rate, we get realistic results, it may be the first time in all over the world that we release this kind of study, and translate it directly in a simulation package, and generating many many explanations about why we have so different results between the lab and the production in realistic reaction times, in purity, and in purity resolved by side reactions and more.

So, if you’re talking about practical mixing calculations for the industry, you can look in for VIsiMix in the web search, and you will find a lot of information about how to include mixing into your considerations to be sure that your results will be relevant, reproducible and representative.

What if we have a gap between the element mixer simulator and chemical mixer simulator?

The answer is that the element mixer simulator is a technique used in the Western world in order to calculate results from nonlinear differential equations with numerical methods. In the Western part of the world, computer hardware has advanced to a very high velocity, resulting in many nonlinear differential equations being solved by numerical methods in a simple way. And the way that we transfer between differential equations to equations that are possible to solve by the computer is by defining the differentiation of any function like finite elements.

So, the finite element is what happens at the end of the element, meaning what happens at the beginning of the element and the gap between them. This technique is typically well known and used in the Western part of the world. When we go to the Eastern part of the world, which VisiMix is becoming available to, the method is different. The method is to better understand the physical phenomena and try to reproduce these physical phenomena with physical models that are adapted to the geometry and operation of the equipment—in our case, the Sterile vessel. This is a cylindric equipment with some internal agitator that moves with a motor, giving movement to the flow and generating the mixing.

So, these are the two main differences. To summarize the first method, the one in the Western part of the world: we use more of a mathematical solution. In the Eastern part of the world, the solution is to delve more deeply in understanding the physical phenomena and trying to replace this physical knowledge with models that support what happens in the tank.