On Thursday 22 September the Annual Drying Symposium of NWGD took place. The theme of the symposium was “Dialogue on Drying Technology”, referring to the current energy crisis but also to the fact that the first live symposium again was held after two years of Corona. In the new Omnia building on the campus of Wageningen University, experts in dewatering and drying from industry, knowledge institutes, and academics came together to talk and inspire each other. More than 100 people came to Wageningen, from all over the Netherlands and abroad, to listen to various speakers talking about innovations in the wonderful world of drying. Already in the early morning, at 9 ‘o clock, Maarten Schutyser, chair of NWGD, opened the symposium.
The first speaker at the symposium was Jean Delaveau, from the company Lyophitech. He told us more about the sleeping beauty of freeze drying. Dynamic freeze-drying is a patented invention developed by Lyophitech that makes it possible to improve heat and mass transfers during operations. The invention has several benefits in comparison to conventional drying technologies: productivity can be improved by 200 to 400%, energy expenses can be reduced by 20 to 40% and less bulk loading and unloading is needed. The technology can be used for the freeze-drying of products with a dry matter content ranging between 10 to 30%. Application examples are drying of bacteria, yeasts, proteins, and polymers. Lyophitech is planning to start with the sales of the equipment for the cosmetic-, food- and pharma sector in 2023.
Drying of dairy
The second speaker up was Thom Huppertz, professor of Dairy Science at Wageningen University and Research (Food Quality and Design group) and researcher at FrieslandCampina who gave a presentation about the processing of dairy products. In general, it can be said that there are three main reasons for dairy processing: food safety, shelf-life extension, and creation of a food matrix. For dairy processing, it’s important that the desired and undesired effects of the processing are well balanced. For food safety, pathogens, spoilage bacteria, and certain enzymes must be inactivated. However, it’s also important that the degradations of vitamins, off-flavour formation, and aggregation of proteins are avoided. To get insight into the effects of processing and to find a good balance, a lot of research is being conducted by FrieslandCampina. This is often done in collaboration with universities. One of the examples of recent research is a study about the effect of protein glycation on lysine availability which was executed in collaboration with Maastricht University.
RaPiD – Creating a better understanding of spray drying
To create a better understanding of spray drying, which is needed for a more sustainable future, and since still, a lot is unknown, Stephan Sneijders from TU Delft gave an insight into his PhD project. By modelling the droplet journey within a spray dryer, better predictions can be made on the outcome. However, modelling this journey seems to be nearly impossible. Therefore, Stephen and his colleagues zoomed in and simulated the viscoelastic droplet collisions that take place during the drying process. Their modelling approach, called RaPiD, revealed the first successful results of Maxwell-like rheological behaviour. The model was capable to predict the viscoelastic behaviour of the colliding droplets.
Networking, posters, and pitches
In between the inspiring talks from industry and academia, there were lots of opportunities for networking and getting to know each other. Besides that, several students were presenting their posters on research they conducted related to drying. The award for the best poster went to Anneloes van Boven (Wageningen University and Research) for her project on Controlling Particle Agglomeration in Spray Drying. Runner up was Sriram Ramanathan (UTwente) who presented his poster about Efficient Spray Drying in a Novel Configuration of Milk Dryer. In addition, three start-up companies were presenting their companies to the audience, to get answers to their drying-related issues: Ojóa, a start-up making fruit-based waters, Time Travelling Milkman, creating dairy-free creamy ingredients and Greencovery, recovering useful compounds from food side streams.
After the lunch break, Dr. Luewton L F Agostinho from Wetsus gave a presentation on Electrohydrodynamic Atomization (EHDA) as a tool in evaporation processes. The usage of the electrospraying technique has various advantages over other techniques, as particles are much smaller, energy efficiency is high and no aggregation occurs. EHDA produces charged droplets and controls the dispersion and size of droplets. Moreover, droplets produced by means of EHDA repel each other, increasing and improving the droplet-to-droplet distance. Controlling the aforementioned distance is of special importance since it results in a reduction of post-spray coagulation, and a decrease of wall deposits, the flying back behaviour as well as near interface vapor saturation. About 40% more evaporation has been observed during drying with EHDA, in comparison to drying where no charge had been applied.
The insect market is projected to grow significantly in the coming years. It is expected that in 2030 the market will reach about 700 kt/year. Jan-Willem Heesakkers, project manager at Bühler Insects, updated us on the possibilities (and challenges) in insect drying. For the processing of insects several drying steps are needed. The three main areas of water removal inside an insect processing plant are the rearing, larvae processing, and residue processing area. For these water removal operations, several types of equipment can be used. For example, for the drying of whole insects, it is possible to use either fluidised bed drying, belt drying, rotary drum drying, or microwave drying. For insect processing companies’ further optimisation of the drying processes is needed. Thereby, it is not only important to realise efficient and sustainable drying processes, but also to guarantee the preservation of the quality and digestibility of the products.
Drying of carbon black
Although you could get the feeling that drying is only a hot topic in the food industry, outside the food world there is even a larger drying world to discover. Gert-Jan Teekman from Hosokawa Micron B.V. showed the importance of drying technology in the carbon black industry. Carbon black is a high-tech material used in many kinds of products such as batteries, automotive, tires, plastics, electronics, dyes, and pigments. Enormous quantities are produced each year, mainly from oil, but carbon black can be recovered from old products as well. To prevent landfill, Hosokawa designed a closed loop system in which carbon-black can be successfully recovered, without the current explosion risks. This is done by a combination of suppression and a pressure shock resistant system, which leads to a negative carbon footprint in the end, a sustainable solution!
Spray drying of eggs
Another interesting presentation was given by Harm ter Stege from Schaffelaarbos, about the feed-grade spray-drying of eggs. Schaffelaarbosis processing left-over eggs from basically everywhere,into feed materials. However, currently they are facing higher costs for gas and electricity, making their processing becoming less profitable. By introducing several adaptations to their production facility, they were already able reducing both gas and electricity use by 15%. This was achieved by the introduction of a desiccant wheel, conditioning of the inlet drying air, pre-heating the egg liquid in a heat exchanger before the final drying step and reusing exhaust air within their complete set-up. Relative small changes made a significant difference for this company and it was inspiring to see the implementation of ongoing improvements in the process industry presented by a young expert.
From wet droplets to sticky particles to dry powder: insights from single droplet measurements
The last presentation of the day was given by Ruud van Ommen from TU Delft. The presentation gave the audience insights in the use of single droplet measurements. After a general introduction about spray drying and agglomeration, the presentation continued to mapping the concentration profile in single drying droplets. For this Optical Coherence Tomography (OCT) was used with TiO2 as tracer particles. Upon placing the tracer particles in the droplets, the liquid movement inside the droplet could be visualised being an indicator of concentration development. Subsequently, the focus shifted to measuring stickiness relevant to agglomeration. Stickiness tests can be divided into two types: static (which tests long-term behaviour during storage) and dynamic (which tests behaviour during production and processing). Lastly, set-ups for studying collisions of drying droplets were evaluated, using the examples of a particle ejector and a falling droplet column. The presentation was finally concluded that further steps in regime mapping of collisions are needed but are also challenging.
For those registered, the day ended with dinner in the Omnia Building. The chefs prepared a three course dinner which aligned with the interest of the NWGD audience: each dish included a special dried ingredient! NWGD can look back at a great symposium at which all members learned a lot from each other and there was ample opportunity for ‘Dialogue on Drying Technology’!
Authors: Jochem van der Tuin, Klaudia Gawronska & Anne Swinkels