As it was mentioned above, the SE6S may be divided into the two subsystems; the first one is the parabolic trough collectors field. In this field a fraction of the normal beam radiation is converted into useful energy to be used to heat the working fluid (thermal oil) from 304°C to 390°C. The second subsystem is the power block consisting of a conventional plant operating with a Rankine Cycle and capable of generating 80 MW. Both subsystems are interconnected with heat exchangers where the hot fluid is employed for steam generation at 100 bar and 371°C which in turn will be used to produce useful work in the turbine.
The basic components of the solar field are the parabolic trough collectors, which consist of three elements: a) The parabolic trough mirrors which concentrate part of the incoming solar beam radiation; b) the absorber pipe, covered with a high absorptance film, and c) a glass envelope around the absorber. This cover minimizes the convective losses from the absorber to the environment (Because of the vacuum existing in the annular space, these losses can be neglected). Additional information about the parabolic trough collectors assembly is given by Kearney and others (1989).
The inlet working fluid is distributed across 142 loops formed by 6 serial solar concentrators. The outlet fluid is then directed to the heat exchangers to generate the steam pa:the required conditions.
The power block consists of a steam turbine that works at high and low pressure. In this turbine three extractions are made; the first one goes to the open heater, and the other two are directed to closed heaters with drains cascaded backward. The main flow leaving the turbine goes to the condenser where it is mixed with the steam arriving from the closed heaters. The condensate liquid is pumped across the closed heaters to be mixed with the first extraction in the open heater. The final product is pumped to the steam generator (heat exchanger) where it receives the useful energy from the solar field thus obtaining a superheated steam at 100 bar and 371°C.
