Concentrated solar power (CSP) plants around the world rely on Steam Generator Systems (SGS) to exchange the energy between the Heat Transfer Fluid (HTF) (Molten salt or Thermal oil) and water to produce steam that runs the steam turbine to produce electricity.
Pic: Steam generation system linking the solar field with the power block (by Aalborg CSP)
As the picture of steam generation system in CSP plant shows, the technology typically comprises of an economizer, an evaporator, a superheater and two reheaters.
As studies have previously shown, the CAPEX investment of a CSP plant can be divided into:
|energy harvesting section||70%||Engineering, TES, MS system and Solar field|
|electricity producing section||29%||Engineering, Power block and Electric
|Steam generation system||1%||steam producing components|
Though only 1% percentage in the CSP plant investment, Steam Generator Systems play an essential role in linking the energy harvesting and electricity producing sections. If the steam generation system is not working seamlessly, power production is entirely affected technically and economically. When a steam generation system requires repairs, the entire plant is forced to be shut down. The ultimate result is loss of revenue. Therefore it is crucial for the bankability of solar plants to have a steam generator system which is not only performing according to specifications, but also extremely reliable.
Pic: The area of the triangles represent the CAPEX investment in a CSP plant (by Aalborg CSP)
Based on experience from the Aalborg CSP service department in Seville, Spain, it is becoming evident, that the majority of steam generators in CSP plants around the world are having problems with leakages. Leakages originate from the transient loads that characterize a CSP plant due to daily startups and shutdowns. Such technical errors can easily contribute to unwanted technical and economic consequences. When water gets into the heat transfer fluid, cavitation problems in HTF pumps may occur. The leaking steam accumulating in the pipes will require venting every day and the plant may also face water hammer problems during start-ups. When the water becomes contaminated by HTF, equipment and instrumentation are risked to get damaged and the facility can be exposed to fire which may occur in the turbine and power block.
A leakage usually takes 4-5 days to repair. During a repair, a steam generator needs to be drained and cooled down. Throughout this period, the system cannot produce steam for the steam turbine, which results in a massive loss of revenue. A five day repair during the summer months can easily cost up to 2% of the plant’s annual income.
When comparing above technical and economic consequences with the efforts allocated to solar field component improvements, it becomes quite obvious that choosing the right steam generator system is extremely important for a CSP plant.
To highlight these crucial consequences, Aalborg CSP set a new standard in the CSP industry and launched a 5-year “NON-LEAKAGE” guarantee on its boiler equipment that are all developed based on the traditional power boiler principles. This assurance is a result of the excellent performance track records of Aalborg CSP’s header and coil type heat exchangers that have been operating without any leakage failures since their first introduction.
Headquartered in Denmark, Aalborg CSP A/S is a world leading steam generator provider for CSP plants. Since its entry to the CSP market in 2007, Aalborg CSP has been devoting to continuous product optimization efforts and is able to provide products like thermal oil SGS3, molten salt SGS4, oil-salt heat exchanger, molten salt receiver and direct steam receiver for CSP plants, including Spain 5 x 50MW plant, Spain 20MW + 10MW tower plants, India 50MW Godawari & 25MW Gujarat Solar One, China Jinfan Akesai 50MW Molten Salt Parabolic Trough Project and many more demo plants around the world.
Pic: Aalborg CSP steam generation system
As one of the leading emerging CSP markets, China is actively developing the 1st batch 20 pilot CSP projects with total capacity of 1.349GW, and to allocate 5GW CSP capacity by 2020. As one of the most important markets for Aalborg CSP business, Mr. Jens Taggart Pelle, Vice President of Technical Sales of Aalborg suggests, “Reaching low FiT levels touches upon CAPEX, OPEX and performance issues. New markets, however, tend to mistakenly confuse low tariffs with reduced CAPEX levels as they lack operational experience. It is therefore essential that China recognizes long-term cost saving benefits of operational features when selecting technologies that they will commit to for the next 25-years”.
To further share the SGS experience and CSP project improvement suggestions, Mr. Jens Taggart Pelle will speak on the upcoming CSP Focus China 2018 conference on March 22-23 in Beijing, and Aalborg CSP will also showcase their expertise and world-wide projects in the exhibition zone.