Following a substantial investment, Afrox recently commissioned an upgrade to its carbon dioxide (CO2) recovery plant in Sasolburg.
Afrox is the country’s leading supplier of food grade CO2, producing the purest refined CO2 in the country. The upgrade has boosted the capacity of its existing CO2 recovery unit in Sasolburg from 150 tonnes per day (tpd) to 250 tpd - significantly increasing Afrox’s total capacity to supply food grade CO2 to several global brands and generally improving security of national supply.
In tandem with this development, Afrox has also boosted its CO2 distribution capacity countrywide. Its CO2 distribution fleet makes use of an intelligent forecasting and scheduling system. By analysing historical consumption patterns and real time information, the system keeps a constant watch on customer stock levels, allowing the company to anticipate needs before they occur and to give customers a seamless supply of this production-critical product.
Food and beverage grade CO2 is achieved through Afrox’s PremierGuard analytical systems, which conduct on-line analysis, batch and lot or tanker analysis to the latest industry standards. Tests include global standard ISBT (International Society of Beverage Technologist) tests.
Afrox sources raw CO2 from refineries and then subjects it to a scrubbing process. The purification process comprises eight discrete forms of refinement to achieve a purity of no less than 99,9%.
First the raw gas is cooled in the pre-cooler unit, then compressed to 22 bar, after which a catalytic oxidation unit removes hydrocarbons. A dehumidifier removes water, after which a dehydrator and activated carbon filter dries it further while removing alcohols and aldehydes. Further purification follows, after which it is cooled once more and the final processes, ammonia compression then liquefaction, are conducted.
The CO2 is then transferred to storage tanks where it is subjected to a batch testing regime before receiving certification. Next, it is pumped into tankers for distribution to Afrox’s bulk customers – most of whom are beverage producers of both soft drinks and alcoholic beverages. Each tanker load is also tested and certified before dispatching.
Bulk CO2 is used in many other industries, including foundries, water purification plants, welding applications, fresh food packaging and storage, food chilling and processing, industrial cleaning, wine making, fire suppression, pest control, rose and tomato growing, dry ice manufacture and ship purging. CO2 is packaged into cylinders at Afrox production sites for applications such as shielding gas for welding, special gas mixtures, medical gases and food packaging.
Donal Mackinnon, Afrox General Manager Tonnage says: “We’ve pulled out all the stops to make sure we remain a reliable source of the cleanest, purest CO2 on the continent. The Sasolburg facility is our most significant source of CO2, centrally located to support the national demand as well as that of neighbouring countries.
“This development is part of a multimillion rand investment programme launched in 2007 to increase capacity and improve the reliability of Afrox’s gas processing plants throughout South Africa. Currently the food and beverage industry, specifically the carbonisation of beverages, dominates the demand for CO2, while pH control for water treatment, shielding gases for welding and other metallurgical processes make up the balance.”
The Afrox team is now in the process of installing equipment that will allow the recovery unit to be remotely monitored by Linde out of Bethlehem in the USA, which is a Linde centre of process excellence for CO2 operations. Mackinnon says the team has adapted the US remote monitoring technology using an on-site analysis process, to ensure that the product remains on spec.
Plans are in the pipeline to increase CO2 storage capacity to further improve security in supply at the site.