The fourth configuration of Aalborg CSP's steam generator technology using molten salt as heat transfer fluid (HTF) has been developed based on the exceptional operational experience with the thermal oil steam systems.
Value-adding engineering design
The optimized fourth configuration of Aalborg CSP's steam generation system is developed as shell-and-tube type with Header-Coil equipment complying with ASME and TEMA standards. The most significant feature of this optimized configuration is that it allows all components to have molten salt on the shell side, while maintaining the option of using natural circulation for optimal and stable operation below 140 bar. Furthermore, for the evaporators Aalborg CSP selects a suitable tube material, which can operate with high temperatures sustaining normal blow-down levels during operation. This translates into operational benefits and up to €4 million initial CAPEX saving on auxiliary equipment for the steam generation system designed for a 100MWe reference plant as well as lower operation and maintenance costs for two main reasons:
1. No need for circulation pumps
The natural circulation in the evaporator unit eliminates the use of circulation pumps and the initial investment costs associated with it. Furthermore, the electricity consumption and the risk for operational failures are greatly reduced.
2. Reduced amount of venting and drain valves
The elevated layout contributes to automatic venting and achieves easy draining as the Header-Coil heat exchangers allow the molten salt to flow by gravity alone. Therefore, there is less need for venting and draining valves, enabling the customers to save on auxiliary equipment that would normally be required, which consequently makes operation and maintenance of the plant easier.
Header-Coil no-leakage design
The Header-Coil technology has been optimized to reduce the cost of equipment utilizing the full counter flow principle, which also eliminates leakage risk as the Header-Coil design absorbs thermal stress. The material selection for the evaporator tubes is optimized to avoid stainless steel corrosion cracking as austenitic stainless steel is not recommended - or even prohibited according to ASME - for water-wetted environments. Combined, these component design optimizations reduce the weight of the equipment significantly and lowers CAPEX of the system by more han 10 %.
- Leakage-free design: By eliminating operational mistakes and risk for downtime, productivity and the general payback time of the plant is greatly improved. As a result of excellent performance track records, Aalborg launched a 5-year guarantee against leakages for the new SGS4 steam generation systems.
- Rapid ramp-up of 10 °C/min: The fourth configuration of Aalborg CSP's steam generator technology allow a fast ramp-up every morning and at transient clouds. The rapid start ensures more than 30 minute extra energy production of a 9-hour daily operational time and increase daily revenue accordingly.
The general principle of constructability characterizes the design of our steam generators to minimize installation work on site and the economies associated with it. The molten salt boiler systems are all developed to perfectly fit into the plant layout. They are prepared for direct mounting on site, and interconnection piping is also pre-fabricated to reduce the time spent on installation.
Secured to be delivered
As a Danish company, Aalborg CSP A/S has the advantage of arranging loan guarantee through a Danish state owned export credit agency. The agency insures banks against the potential financial and political risks – thereby securing the loan and delivery of our molten salt steam generation systems without financial obstacles.