Northam Platinum’s Booysendal Mine
GENERGY: 30-kL Solar system with 192 m2 flat plate collector
TOTAL M2 Panels 192
Tank Storage 30,000
Year Commisioned 2012
Tank Construction Mild Steel, Vertical
High / Low- Pressure Storage High Pressure
Litre / m2 156
Energy Savings / Annum kWh 548,000
SHORT DESCRIPTION OF THE SYSTEM
Every mineral processing facility knows that a rand saved on overheads is a rand gained towards the sustainability of the facility. Traditional methods of water heating, such as electrical resistance heating, have been used for years in the South African market with great success and reliability. With the rise in energy costs in South Africa over the last few years, consumers have become more innovative in their approach to energy efficiency and renewable energy.
Fortunately for Northam Platinum their management team has established those improvements on the energy efficiency of their facility is a fantastic way of reducing overall operational costs. Thus, when Genergy was given the opportunity to partner with Northam Platinum on the newly built Booysendal Division, we jumped at the opportunity. The opportunity allowed Genergy to design, supply, install and commission an energy efficient hot water system making use of solar thermal technology as the primary source with electrical resistance heating as a secondary source.
“Projects like this are an investment in the future of sustainable mineral processing”
The energy efficient hot water system at the change house of the facility was designed to accommodate up to 1000 users per day over two 12 hours shifts. This equated to 60 000 litres of hot water at 60°C per day. From the 60 000 litres of hot water used per day approximately 15% is used in the nearby laundry for washing. The project was implemented in 2 phases, the first phase accommodating 500 users and the remainder of the users over a duration of 5 years.
Ample roof space was available for the implementation of solar thermal technology and a boiler room was specifically designed to house the hot water storage vessels.
CHARACTERISTIC’S OF THE SYSTEM
A total of 96 flat plate solar thermal collectors, each covering an area of 2m², were installed at a tilt angle of 28° to ensure optimal year round performance of the solar thermal system. The orientation of the building was North West which allowed for maximum afternoon solar yield. The collectors were installed in 4 banks of 6 in series and 4 in parallel on the Tichelman’s reticulation principle to ensure uniform pressure and temperature of the solar collector array. Two inline circulating pumps, controlled by a temperature differential solar controller, ensured the optimal flow rate of the fluid conduit inside the closed loop. The fluid conduit exists of a 60% water and 40% food grade glycol mixture to prevent freezing and overheating of the closed loop. Expansion tanks were used to accommodate expansion and retraction of the fluid inside the closed loop. The internal heat exchangers fixed inside the hot water storage vessel were made of a corrugated flexible metal hose to increase surface area and promote better heat transfer to the water inside the vessel.
The hot water storage vessels had a combined storage capacity of 30 000 litres, each one being 15 000 litre. The electrical resistance backup heating capacity of vessel is rated at 90kW to ensure sufficient hot water recovery between usage peaks even when no solar radiation is available. The vessels and all associated pipework is lagged and cladded to reduce heat losses in storage and reticulation.
A reduction of 60-70% in the energy used for water heating is achieved, thus a reduction in operational cost of the facility. Work load of the electrical resistance heaters are reduced ensuring longer lifespan and reduced maintenance/replacement cost 60-70% reduction in carbon emissions when compared to electrical resistance heating
A payback period of less than 5 years and an effective lifespan in excess of 10 years & resulting increased value of the facility.
Tel: +27 86 115 9159
Address: 3 Alabaster Road, Baakens Valley, Port Elizabeth