Industrial gases market leader Afrox has been awarded a long-term contract to supply high-purity nitrogen, and liquid petroleum gas (LPG), to the (US) $565m Bokpoort CSP Project.

Located approximately 125km south-east of Upington, the Bokpoort CSP will boast a 50mWe generating capacity with nine hours of thermal storage once it is fully commissioned by the end of 2015.

Afrox business manager for bulk ASU gases, Carte Lubbe explains that the company is supplying Bokpoort CSP with a fully-customised turnkey solution unique to the local market. He says, “LPG will be used by the CSP during the start-up phase for melting of salts for the Thermal Energy Storage system, whereby the transfer medium is heated to the point that it transforms from a solid state into a molten state.”

The substantial amount of LPG is, however, only required during the heating phase of the project. As a result, Afrox has designed an innovative modular supply system that will be installed and can be dismantled and removed from site within days, thereby ensuring minimal project disruption.

Following the heating of the molten salts, a blanketing system is required in order to minimise the risks due to flammable products, as well as minimising the emissions to the atmosphere and to avoid the deterioration of process fluids. For this reason, the plant will include a nitrogen network that will provide an inert atmosphere to the salt storage tanks, the expansion tanks and the high temperature fluid boiler.

Lubbe reveals that the company has been working together with Bokpoort CSP to develop a nitrogen supply system to meet its specific needs. “As a result of the critical need for nitrogen, special care was taken to ensure that all aspects of demand and supply had been considered. The nitrogen supply system comprises an on-site nitrogen production system, backed up by a high pressure liquid nitrogen storage and supply system,” he said.

The on-site nitrogen generating facility is supplied by Afrox’s parent, the Linde Group Engineering division, while the cryogenic storage facility and custom designed nitrogen reticulation system is supplied by Afrox. A long-term nitrogen supply agreement between Afrox and Bokpoort CSP has been concluded, ensuring an uninterrupted and reliable nitrogen supply to the project.

Lubbe indicates that due to the location of Bokpoort CSP, Afrox is able to supply the back-up liquid nitrogen via road from several of its regional operations across South Africa, thus providing even more security in supply.

In addition to using LPG and nitrogen supplied by Afrox, the Bokpoort CSP also made use of the company’s extended product range of welding gases, hard goods and consumables during the construction stages. “Afrox has provided a comprehensive and holistic solution to Bokpoort CSP, which will lead to a long-term and mutually-beneficial partnership,” Lubbe concludes.

Afrox is well positioned to support potential future CSP projects with a total solutions offering, having gained an in-depth understanding of the specific requirements, as well as challenges faced by various role players and stakeholders throughout the execution of CSP projects and eventually by the operating entity.