Energy Conversion and Management: X (Jan 2024)
Prototype plant for indirect low-pressure steam generation with Fresnel solar collectors: Sizing and commissioning tests
Abstract
Concentrating solar Fresnel technology is a promising option for renewable solar heat generation in industrial processes. There are many sectors with medium and low-temperature heat demand in which water could be used as a heat transfer fluid (HTF), without the drawbacks of thermal oils in indirect steam generation systems. However, this technology is not widely used and there is limited experience in its design, control, and management. This justifies the significance of this work, in which a Fresnel collector solar plant for low-pressure indirect steam generation was dimensioned and adapted to the constraints imposed by its location in a real industry. Water is used as primary fluid, and the steam generator is a kettle reboiler. A simplified method based on the incidence angle modifier (IAM) was developed and applied to estimate the expected efficiency and power, and to size the plant accordingly. This method proved to be valid for predicting the behavior of the system, although it overestimated the power output. Further analysis is needed in order to improve the results. The main components of the system, the variables and control parameters were described. Several commissioning tests were carried out to verify the methodology used for the plant sizing, to analyze its performance, and to optimize the value of different control parameters. The minimum global radiation required to start the system was defined as 200 W/m2 during a minimum time of 300 s. This radiation level prevented start-ups during hours when the expected energy generation was lower than the energy consumption. It was also observed that decreasing the frequency of kettle water refilling reduced its negative impact on the steam generation process. This solar plant will be useful for future research involving tests under different working conditions, modeling, system optimization, and analysis of energy and steam production or soiling influence.
