This year’s theme of the NWGD symposium was: ‘Reducing the carbon footprint and energy use in industrial drying processes‘. Chairman Maarten Schutyser opened the symposium and pointed out the extreme weather experienced during summer holidays by many people. It is time for action, reducing energy use and cutting down GHG emissions. It is also fully in line with the mission of NWGD to stimulate development of sustainable dewatering and drying technologies while providing high quality foods. A coherent program with a diverse set of speakers was invited around the theme.
First, Joost Beekman presented on behalf of DSM about the “Process development of CanolaPRO plant protein.” From this presentation we learned about the production of a plant protein ingredient from rapeseed via spray drying for application in the new CanolaPRO product. Using the press cake after producing canola oil, the protein was extracted and evaluated for its functionality. It was found that the proteins were soluble across the full pH range while also showing foaming behaviour. From here the process was scaled up to the pilot plant scale, where dust explosion and stickiness were evaluated to come up with a robust and safe process. With the new protein extract, DSM was able to create the so-called CanolaPRO snack, which was available to taste during the morning break.
The second speaker Artur Pozarlik from the University of Twente presented about his research on viscous independent spray atomization. Most atomisers currently used in the industry are only suitable for low viscous fluids or have high operation costs. Moving to high viscosity feeds is important to save energy during spray drying operations. Artur emphasized the potential of flow blurring atomizers, which exhibit distinct advantages, particularly in atomizing high-viscosity liquids. These atomizers are characterized by their robust design and resilience to variations in mass flow. Subsequently, Pozarlik delved into the comparative analysis of the atomizers, highlighting their ability to achieve higher droplet density, resulting in smaller droplet sizes. Notably, even as the viscosity of the liquid increases, the atomizers show a modest change in droplet diameter in comparison to alternative atomization methods. Additionally, changing the airflow does not significantly impact the droplet size, reaffirming the stability and consistency of this atomization approach.
Sebastien Heymans from the Belgian company Lessine presented about energy saving strategies in rotary drum/flash and combi milling/drying technologies. The main energy needs of these convective dryers are thermal and electrical. For thermal 70-80% of the energy is required for water evaporation, furthermore the energy is lost via the chimney 5-25%, warm surfaces 5-10% and heating of the product 7-12%. Electricity is used by the main fan 50-75%, rotation motor 20-25% and fluidizer 25-50%. The energy used to heat the product can be recovered by transferring the energy from the outgoing product to the incoming air, which can potentially save 5-10% energy. To recover the energy loss at the chimney, indirect heat recovery can be used at a low RH, by placing two heat exchangers at the beginning and end. The outgoing air is cooled and reused to heat the incoming air, resulting in 5-8% energy savings. With a low RH, partial gas recirculation can be used, where part of the outgoing gas is returned and combined with the incoming air. This can provide an energy saving of 5-15%. In addition, process parameters can be optimized to save more energy. The incoming temperature of the gas must be as high as possible while the outgoing temperature is as low as possible. Finally, overdrying products should be avoided, which again also saves energy.
Subsequently, 5 PhD students gave pitches on their PhD projects. The first was Sriram Ramanathan from UT, who discussed his modelling research on radial multizone dryers. Cristine Garcia Llamas from TUe present her research about numerical simulation of droplet breakup during spray atomization. Julia Veser from the WUR introduced her work on drying of high-quality vegetable seeds. Vivekanand Swami from TUe shared his experimental research on spray analysis for spray drying. Finally, Nienke Eijkelboom from the WUR presented her work on single droplet drying for better spray drying.
After the lunch and poster session Jan van Pijkeren from SiccaDania, a subsidiary of the Invex Group, gave a presentation about energy saving options in spray drying. SiccaDania is a company offering advanced processing solutions and equipment for the dairy, food, and pharmaceutical industry. An important expertise is to enhance the efficiency of powder processing. This is pursued for example by development of refined sanitary bag filters and multicyclones, suited for the optimal recovery of powder from exhaust air streams. Jan van Pijkeren explained about innovative designs aimed at recuperating heat from the spray drying process.
Donato Rubinetti presented for EMPA (Switzerland) about “Electrohydrodynamic drying: technology & future applications.” Essentially, electrohydrodynamic works by ionizing the air around a high voltage wire causing the air to move towards a grounded electrode. Although the scale is currently too small for industry use, this novel technique is highly efficient with low energy use and thus lower environmental impact. The researchers are currently looking into scaling up the technique to be used for wind generation and sanitizing air for food processing and cold storage.
Geert Raymaekers from CEE (Belgium) presented about superheated steam drying using heat pump technology to realise a zero carbon dryer in the ceramic industry. Specifically, Geert provided insight into an improved process for drying bricks with superheated steam. In the first part of the project it was determined if superheated steam drying would be the best method to dry the product. If mechanical dewatering is an option or if excess of electricity or residual heat is available then superheated steam may not be the best method. If superheated steam drying is possible, this can provide an energy reduction of 25% over conventional air drying. The bricks are brought into direct contact with the superheated steam resulting in the water evaporation. Part of the water is removed from the system and the rest is heated and recirculated again into the drying process. By creating a hybrid system of superheated steam and a heat pump, energy reduction can be further increased. The combination of the two techniques can further reduce energy consumption by 66%
The final presenters of the day were Violet van Kogelenberg and Nikolas Charamis from Nestlé Nunspeet. This company is primarily engaged in the production of spray-dried infant formula. Nestlé has set ambitious sustainability targets, aiming to reduce its CO2 emissions by 50% by the year 2030 and achieve net-zero emissions by 2050. To accomplish these sustainability objectives, Nestlé has implemented a strategic approach focusing on the efficient utilization of energy resources within their spray drying process. One key initiative involved the harnessing of exhaust air energy, a valuable resource within their manufacturing operations. Specifically, they are repurposing hot air at approximately 85°C as a source to heat the cleaning liquids essential for spray dryer maintenance. Additionally, air within the temperature range of 60°C to 38°C is effectively utilized as a thermal source for the spray dryer air, further optimizing energy usage. Following three years of production and ongoing enhancements, Nestlé’s efforts have resulted in an average recovery of 20% of energy in the overall process.
The last presentation was given by Anneloes van Boven from Wageningen University pitching highlights from Eurorying 2023. This conference was held in Poland and she visited it thanks to winning the poster award during the NWGD 2022 symposium. The NWGD symposium was concluded with a great dinner in the Omnia restaurant.
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Nederlandse werkgroep drogen
De Nederlandse Werkgroep Drogen (NWGD) stimuleert de ontwikkeling en toepassing van duurzame droogtechnologie in Nederland. Sinds 1974 verbindt de NWGD droogexperts in Nederland door thematische excursies, symposia en andere activiteiten.