GEA looks at Computational Fluid Dynamics (CFD) and explains how it can provide more accurate costing, achieve greater accuracy in design, provide better process insight and significantly reduce risk for customers of spray dryers for food ingredients, starch and proteins.
Computational Fluid Dynamics, in the context of spray drying for food ingredients, starch and proteins, is a proven technique to establish how products behave during drying, on a computer - before you get down to the hands-on engineering.
CFD is hardly unique in industry. Many sectors, such as aerospace and the automotive industries, use CFD as an integral part of their product development processes. But when it comes to the spray drying of food ingredients, starch and proteins, there are other variables that are at the center of everything: the customer and product.
Stig Skalshøj Christensen is a sales engineer with GEA. He said that every customer and every product is different. “Customers are working with different raw materials and are often looking to achieve subtly different outcomes. If we are to give those customers the confidence they need to choose our technology, we need to make sure we really understand them, their products and what they are aiming for.”
Kristian M. Ingvorsen, is Head of CFD at GEA. He summed up the benefits of the process for customers. "First of all, all testing is done on a computer, not on site,” he explained. “When done on site, testing is difficult and expensive. Computer simulations provide a low cost, zero risk testing environment. Secondly, modeling provides deep process insight, allowing you to get detailed understanding of how changes in different input parameters impact the process as a whole. This is clearly superior to the traditional trial and error approach, where a lot is left to speculation."
Asian soya protein plant
Stig Skalshøj Christensen gave an example of a soya protein plant in Asia. The company was already running large spray dryers but wanted to double its capacity. To do this it preferred to use just one large dryer however such a large machine had not been used before for this application. It was necessary to find out if it could be done and, if so, what would be the specific design characteristics of the dryer that would allow it to operate efficiently and provide the quality of final product required by the customer.
“Our CFD team were able to use data from a large dryer running a similar product, feed that into the computer model, then increase the size and capacity of the chamber to see how it behaved. Only when they had proved that it was technically possible to build the dryer did we present it to the customer. The customer accepted our proposal and the project is currently underway. Having just one dryer will save the customer a great deal of money in capital purchase, installation and building costs. This would have been far too risky without the benefit of CFD and the customer would probably have compromised with two dryers that would have been more expensive and less efficient.”
Keeping it small
It’s quite possible for the calculation to go the other way. Perhaps a customer believes it needs a dryer of a certain size but, through CFD, GEA engineers can demonstrate clearly that it will be possible to achieve the same result with a smaller machine. “Again, this will save them money, not just on the dryer but also on the installation, building work and long-term running costs,” said Stig. “The smaller the dryer the better, as long as it can do the job.”
The real skill
Lars Voigt is Head of Engineering Data and Tools Management at GEA. He said that it is important to work as a team with colleagues to combine the knowledge that exists of the customer and the application to feed in the most accurate data possible to what he calls, the Virtual Test Bench. GEA has standardized the reports that come from the Virtual Test Bench to speed up the process and help Lars to provide useful information that can be used to make critical decisions.
“This is where the skill comes in,” he said. “We are experts in making modelling assumptions and adapting the models so we can make fast, reliable decisions. We interpret the data from the CFD system to show how a piece of equipment can be customized for an individual customer. It’s about converting data into knowledge. What’s more, we need to do it quickly.”
Time is money
And by quickly, Lars means very quickly. “Because we use trusted ways of operating and have the back up of our experienced team, we can often produce conclusions inside two weeks where our competitors, who might need to conduct a research project, would take two years or more.” Speed is also important when troubleshooting. This could involve running simulations to see why deposits are accumulating in a dryer and, more importantly, what adjustments need to be made to solve the problem.
But there are other, longer-term uses for CFD. Product research and development is a continual process at GEA and much of it is reliant on CFD analysis to drive product evolution and new product development. But, according to Lars, this takes on secondary importance when presented with an urgent challenge. “Our projects always follow the timeline of our customers, internal or external.”
The practical benefits
So, CFD, when combined with GEA’s engineering expertise, can be a powerful tool. It can be used to reduce costs; to quickly assess the consequences of design variations in products; to provide early insight into the design process and avoid the need for physical testing; to give developers a visual flow of information from any point on the system that would be impossible using sensors or gauges; allows designers to model any set of conditions to test differential flow and heat transfer processes; and gives designers the freedom to experiment, sometimes pushing parameters to the extreme.
The GEA factor
GEA has over 50 years of experience in process engineering for the food ingredients sector which is reflected in the number of operating plants worldwide and the unrivalled knowledge of the company’s process technologists.
Stig Skalshøj Christensen believes that CFD, combined with this long experience and extensive product and process knowledge, is both unique in the industry and helpful in giving customers confidence that GEA solutions are robust. “The software in itself is not enough,” he said. “It’s the vision, expertise and experience of the team behind each project that matters. Customers need to know that we are not just relying on what the computer tells us, but that we are using technology to apply our experience in a practical way. I believe that GEA can do this better and faster than anyone else, especially when it comes to these very large dryers that require our particular skills.”
Every customer wants to know that spray drying plants are designed specifically for their application and are working at an optimum level. In the old days, this inevitably meant an element of compromise, of playing it safe. Today, through CFD modeling, it’s possible to push those boundaries much further, giving customers a commercial edge in a competitive market and allowing them to develop new products safely, quickly and inexpensively.