In order to meet emerging market expectations for lowering cost of energy for molten salt technologies, Aalborg CSP has developed a new configuration of its steam generation systems. The SGS4 configuration is reusing the proven components with a new arrangement, allowing it to maintain key operational benefits from the former design, such as fast start-up, guaranteed leakage-free operation and low maintenance requirements.

To meet large-scale concentrated solar power (CSP) plants’ critical requirements for high availability, the optimized SGS4 system is developed as shell-and-tube type with header-and-coil equipment complying with ASME and TEMA standards. The most significant feature of the optimized SGS4 technology is that it allows the shell-and-tube design to have molten salt on the shell side of all components while maintaining the option to use natural circulation for optimal and stable operation. This translates into up to €4 million saving[1] on auxiliary equipment for the steam generation system as well as lower operation and maintenance costs for two main reasons:

1. Firstly, the natural circulation in the evaporator unit eliminates the use of circulation pumps and the initial investment costs associated with it. Without the need to use circulation pumps, the electricity consumption and the risk for operational failures are greatly reduced.
2. Secondly, the components (evaporator, superheater, reheater, economizer) are placed in an elevated layout, contributing to automatic venting and achieving easy draining as the molten salt flows by gravity alone. Therefore, there is less need for venting and drain valves, enabling the customers to save on supporting equipment that they would normally have to purchase. The reduced amount of valves also makes operation and maintenance of the plant easier, especially in typical cases, such as molten salt crystallization, when cleaning of multiple valves becomes a costly burden.

To increase cost-competitveness of the system itself, the SGS4 configuration allows smaller material thickness owing to an upgrade in the placement of tube bundles and pipes. While the basic component design is the same as the previous editions, decrease in the material thickness reduces the weight of the equipment significantly and lowers CAPEX of the system by 10%.