The solar field is a modular system of solar collector loops connected in parallel by means of insulated pipes. Each loop is a set of 4 Solar Collector Assemblies (SCAs), each consisting of 12 Solar Collector Elements (SCEs) with 12-metre-long and roughly 6-metre-wide parabolic mirrors. Cold Heat Transfer Fluid (HTF), flows from the HTF pumping area into a cold HTF header that distributes it to parallel loops of SCAs in the solar field. The HTF flows through the absorber tubes on its way from the cold to the hot header pipe. It is heated in the loop and enters the hot header that returns the hot HTF from all loops to the power block area. In normal operation the HTF enters the solar field at about 290°C and leaves it at about 390°C.
The SCAs collect heat via a trough of mirrors of parabolic geometry. The mirrors focus the Sun´s Direct Normal Irradiation (DNI) onto a line of Heat Collection Elements (HCEs) placed in the mirrors’ focal line. Every collector unit has its own solar sensors and hydraulic drives, which allows the mirrors to track the position of the sun from East to West.
COLLECTORS: PARABOLIC MIRRORS AND ABSORTION PIPES
Mirrors and absorption pipes are precisely mounted on steel support structures which, taken together, form the collectors. The metal support structure is anchored in the ground using a steel pylon. Computers in the control room are used to monitor the power plant’s collectors. Information from each individual collector unit is transmitted during this process and orientation during sunrise and sunset is carried out automatically. The metal structure, mirror elements, and absorber pipe all together form a high-precision device.
Parabolic mirrors |
Absorber tubes |
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| The parabolic mirrors are the optical key components to maximize the concentration, optical performance and durability of the collector. They follow the course of the sun and concentrate the incident solar radiation focusing it onto an absorber pipe in the focal line of the collector.
These reflectors elements are made from extremely transparent, silver-coated glass mounting on ceramics material with a high level of mechanical strength. |
These tubes absorb the solar radiation reflected by the mirrors and transfer the solar energy into a heat transfer medium located in the pipe.
The construction allows maximum absorption of solar radiation and simultaneously minimizes the reflex radiation of heat from the metal pipe. An absorber tube is four-meter long and composed of a multi-layered stainless-steel pipe. The steel pipe is surrounded by a vacuum-isolated concentric borosilicate glass cladding tube with anti-reflex coating. |