African Fusion June 2015

Above: Afrox’s CSP solutions have been supplied to the Bokpoort parabolic trough plant, which requires 20 000 km of pressure piping to be welded, along with the support structures for a solar field consisting of 588 600 m² of mirrors. Above right: Afrox’s modular and portable skid-based container system consists of a series of containerised bulk LPG storage tanks along with all of the evaporators necessary to supply the fuel for the initial salt melt. Centre right: The Bokpoort CSP plant has a molten salt storage system to provide over nine hours of generation capacity after sunset or during cloudy weather. Right: Onsite pipe welding is done using the TIG process for root runs followed by fill and capping passes using low hydrogen MMA electrodes. toprevent thehot salt fromreactingwith moisture and atmospheric gases. “Afrox has developed a custom-designednitro- gen storage and reticulation network to provide the inert atmosphere necessary for the salt storage tanks, the expansion tanks and the high temperature fluid boiler. The system comprises an on-site nitrogen production system, using pres- sure swing absorption technology (PSA), backed up by a high-pressure liquid nitrogen storage and supply system,” says Pieterse. Afrox’s parent, the LindeGroup Engi- neering division, is supplying the on-site nitrogen generating facility, while the cryogenic storage facility and custom designed nitrogen reticulation system has been installed by Afrox. A long-term nitrogen supply agreement between Afrox and Bokpoort CSP has been con- cluded to ensure an uninterrupted and reliable nitrogen supply to the project. Bulk liquid supply is ideal for ap- plications where flexibility is required or uneven demand patterns are preva-

lent. Once the demand at the CSP plant has been established, however, on-site nitrogen generation or a combination of bulk and on-site supply are options that can be considered. Through the Bokpoort CSP project, Afrox has demonstrated its ability to design and deliver reliable systems and services for both the construction and operation phases of CSP projects. “Our supply network covers almost every region in South Africa, but it becomes increasingly less cost effective as the distance from a source increases. We have already opened a branch in Up- pington and are in the final stages of planning for a branch in Katu to support this growing industry,” reveals Afrox’s Pi- eterse. “When you consider that several of coal fired plants may be adding CSP systems to improve their efficiencies, we anticipate up to 22 CSP plants being built by 2030. “And Afrox is well positioned to sup-

In order to ‘blanket’ the thermal storage medium, Afrox has developed a custom-designed nitrogen storage and reticulation network comprising a pressure swing absorption (PSA) nitrogen generation system backed up by a high-pressure liquid nitrogen storage and supply system.

port this futurepotential. Basedonan in- depthunderstandingoftherequirements and challenges during the construction phase of CSP projects, along with our knowledge of the ongoing operating and maintenance needs, we have developed a comprehensiveCSPsolutions offering,” Pieterse concludes.

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June 2015

AFRICAN FUSION