Innovations in algae thermal processing

The customer’s challenge: How to safely transport algae and cool algal oil without affecting its quality

A world-leading company in lactic acids (and derivatives), emulsifiers, enzymes, minerals, vitamins and algae ingredients, challenged Dinnissen to come up with a way to homogeneously cool algae oil.

The problem is that when algae are stored, they begin to fester, and the algae become thermally unstable. As a result, self-combustion can occur. This makes it dangerous to transport them. This was also the problem of Dinnissen's customer, who had an algae production plant, but could not transport the algae. Therefore, they built a production line in which the algae are dissolved in oil. Dissolving algae in oil requires heat. The algae are heated and dried with roller dryers, after which it must be cooled again. Dinnissen's expertise was called upon for this process. After several test cycles in-house with pneumatic and mechanical conveying and cooling methods, Dinnissen found the solution: direct and indirect mechanical cooling inside their continuous mixing units.

How does the -direct and indirect- cooling process of algal oil work?

During the heating process the product absorbs a lot of heat. To homogeneously cool the algal oil without causing de-mixing of the product, an inventive cooling system was developed. A key element of this cooling process is that the product is gently mixed continuously during cooling. This results in a consistent, homogeneous output without segregation or decomposition of the product. Even when there are differences in (grain) size, the products are cooled homogeneously, thanks to the continuous mechanical mixing and cooling process. This is an advantage over cooling with conventional cooling methods using fluid beds, where differences in grain size lead to deviations in product temperature.

This cooling system combines indirect cooling with water on the system’s casing, with direct cooling on the product with air. In the direct cooling, a closed loop system is used that circulates the same air. Therefore, continuous conditioning of outside air is not needed. However, to prevent recontamination, it's critical that clean and conditioned air is used for cooling. To provide the required clean air for the drying process, a high-efficiency particulate air (HEPA) filtration system is used. This multi-stage -from coarse, to medium, to fine- and closed-loop filtration system guarantees that only clean air enters the mixer, and that it remains clean throughout the entire process.

This combination of direct and indirect cooling;

• results in extremely effective and efficient heat transfer;
• and allows for a very compact design of the processing unit.