The use of fouling factors is mistakenly requested in concentrated solar power (CSP) steam generator technical specifications. This in turn results in up to 30 percent oversized steam generator components, increased material costs and reduced CSP competitiveness. Aalborg CSP has now removed the myth of this technical phenomenon and introduced a 5-year guarantee against fouling in order to encourage the market towards optimised technology development.
Fouling involves a layer of an unwanted insulating material generated on the surface of a component. This can subsequently interfere with the component’s performance and efficiency. With regard to CSP, this can result from overheating the heat transfer fluid, such as thermal oil, in the solar field due to incorrect operational arrangements. The heat transfer fluid can crack, creating an undesired coating within the receiver tube and carrying the risk of sending solid particles with the HTF flow to the rest of the CSP plant.
A fouling factor is often considered when technical specifications for CSP steam generators are made. This can result in up to 30 percent extra material in the equipment design and higher costs. However, fouling in steam generator designs based on traditional boiler materials, such as ASME and EN power boiler standards, is an often mistakenly applied factor. This is because in actuality the HTF is not heated but cooled in the steam system. Secondly, if solid particles accidentally entered the steam generator it would not be an issue for the header and coil type equipment as they apply large tube diameters and spacing which improves the circulation, thereby eliminating the risk of fouling.
“Ever since our first solar steam generators went into operation in 2008, fouling has never been a problem to us” said Svante Bundgaard, CEO of Aalborg CSP. “Even if plant operational mistakes were made and dirt appeared in the system, a normal boiler chemical cleaning would be able to solve the issue. Therefore, oversizing components by up to 30 percent due to a mistakenly identified specification is not reasonable and will only prevent the CSP market from realizing cost optimization in reality.”
Aalborg CSP has dedicated itself to the task of reducing the Levelised Cost Of Energy (LCOE) of CSP plants and has therefore launched a new standard in the CSP industry while also introducing a 5-year guarantee against fouling for the header and coil steam generators. The intention is to encourage the CSP market towards designing technical specifications that encourage optimised technology development instead of following a repeated structure.
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