Reliable solar steam generation in long-term operation
Practical example: Kean Soft Drinks in Limassol, Cyprus
Reliable solar steam generation in long-term operation
Solar steam for fruit juice factory in Cyprus
View of the fruit juice factory Kean Softdrinks in Limassol, Cyprus. Since 2018 the parabolic trough collector field has supplied steam for pasteurization and inflation of plastic bottles.
The long-term operation of the concentrating collectors in Limassol, Cyprus, has shown that this technology can reliably supply steam even in dusty environments and near the sea. Only regular cleaning of the mirrors is required to ensure continuously high performance.
Demonstrating reliability of concentrating collectors
The parabolic trough system at Kean Softdrinks is a showcase project for the long-term reliability of concentrating technology. The plant heats the thermal oil to a temperature range of 285 to 330 degrees Celsius. The thermal oil of the type Helisol XA is then used in a steam drum to produce steam which is fed into the factory’s steam network operating at around 184 degrees Celsius. The valve between the steam drum and the factory’s steam network, which is supplied by fossil-fueled boilers, remains continuously open whenever the pressure in the steam drum is sufficient to allow injection into the client’s energy grid.
Parabolic trough collector row at Kean Softdrinks
One of the two parabolic trough collector rows at Kean Softdrinks in Cyprus.
The steam is used for two processes: pasteurization of juice and inflating plastic bottles. To save on transport costs, the bottles are transported compressed and then inflated on site using hot air.
Another important component of the plant is the integrated concrete thermal energy storage system, which consists of two modules and reaches temperatures of up to 380 degrees Celsius. The storage unit and the steam drum are compactly housed in shipping containers. The integration of the thermal storage unit allows for more flexible steam generation. This is because after sunset, the factory can only be supplied with steam from the storage facility.
Schema of the solar process heat plant at the juice factory Kean Softdrinks
Schema of the solar process heat plant at the juice factory Kean Softdrinks in Limassol, Cyprus.
The two parabolic troughs rows are located just a few hundred metres from the sea and are therefore continuously exposed to salty air. In addition, summers in Cyprus are often rainless and therefore very dusty. Therefore, the mirrors of the parabolic trough have to be cleaned regularly.
In 2024, the factory operated for juice production on 190 days. The site benefits from a high annual direct solar irradiation of 1,949 Kilowatt-hours per square metre, of which 868 Kilowatt-hours per square metre were available in the collector plane for solar steam generation during the factory’s operating hours.
As part of the ProSolNetz project, the operational data of the solar process heat system for the year 2024 were analysed. The analysis shows a specific annual yield of 370 Kilowatt-hours per square metre per year, corresponding to a system efficiency of 42.6 percent based on the available irradiation of 868 Kilowatt-hours per square metre. With more regular cleaning at ten-day intervals and a minor adjustment of the control settings an improvement to 420 Kilowatt-hours per square metre per year and an system efficiency of 48.4 percent can be expected.
Contact
Dr.-Ing. Eckhard Lüpfert
Head of Concentrating Solar Technologies Department
