Solar power plants with thermal energy storage using molten salt

The latest development in Solar Power Plants is the storage of „thermal heat“, by using solar salts.

The solar energy is caught by parabolic mirrors, reflected and focused on a central receiver tube, in which a heat transfer fluid (HTF), Therminol VP1, Dowtherm A, or equivalent, circulates in a closed loop. The HTF is heated by the solar radiation up to 393°C (740°F), produces superheated steam in a shell and tube heat exchanger train and comes back to the solar radiation receivers at 293°C (560°F). To extend the operation beyond sunshine hours, a thermal energy storage system, consisting of 2 molten salt storage tanks is integrated into the solar plant. The solar energy collected by the solar field during the day is partly used for thermal storage, i.e. charging of one tank at approx. 384°C (723°F).

To discharge this heat when required, the salt is pumped from the hot storage tank, through a shell and tube heat exchanger train, to the cold storage tank and will be cooled down to approx. 292°C (558°F).

In this configuration, the HTF coming from the solar field at 393°C (740°F) is diverted to the heat exchangers, where its thermal energy passes to the salt flow arriving from the cold tank. The salt is heated up and stored in the hot tank. When required, the charging process is reversed and salt from the hot tank is pumped to the same heat exchangers, where the salt returns its thermal energy to the cold HTF.

Bertrams Heatec has the expertise and more than 60 years experience in dealing with molten salt

Experience means the theoretical expertise, improved by the lessons learned during commissioning, including feedback of end users during operation of their plant(s).

The design of the system and equipment must consider experience with salt, i.e. salt creeps, freezes, dissolves graphite, salt has a high density, salt ages when in contact with oxygen, even low impurities and possible insoluble have to be considered (corrosion, abrasion).

Furthermore, an adequate preheating and heat tracing of salt wetted parts (equipment, piping) is required, the pipe routing and piping engineering is not „standard“, the entire system should be drainable by gravity, etc.

What can Bertrams Heatec offer you?

• Design, manufacturing and supply of the complete TES (Thermal Energy Storage) system, including performance guarantees
• Design, manufacturing and supply of the Initial Nitrate Melting system, including supply and handling of the nitrates
• Design, manufacturing and supply of the HTF (Heat Transfer Fluid) back-up heating system, including performance guarantees
• Erection supervision worldwide
• Commissioning and after sales service worldwide

Pictures

Please click to enlarge the images.