Power Recovery Turbines in Mines
About 18% of the electricity demand in South Africa comes from the mining industry. Exploitation of minerals such as gold and platinum from deep mines require large volumes of cooling water as temperatures in the working areas can exceed 40°C. To reduce the temperature, cooling water from a central refrigeration plant at the surface is brought down to depths of about 3,000 m. The warmed water is then pumped up to the refrigeration plant for re-cooling, a process which requires about 14% of the overall electricity demand of the mine. Energy costs and friction losses can be partly compensated for by the installation of power recovery turbines. ANDRITZ HYDRO has already installed more than 50 underground energy recovery turbines with a total capacity of over 80 MW in various mines in South Africa.
Autumn 2016 saw the Preliminary Acceptance Certificate (PAC) signed for the new hydropower plant Stortemelk. Developed for the customer Stortemelk Hydro (RF) (Pty) Ltd. by Renewable Energy Holdings (REH), Stortemelk is located near the town of Clarens in the Free State Province. Aurecon, South Africa provided the engineering, procurement, and construction management services for the implementation of the project.
The scope of supply for ANDRITZ HYDRO comprised the complete electro-mechanical equipment, including one 4.4 MW vertical shaft compact axial turbine (CAT) with a runner diameter of 2,350 mm, the synchronous generator (with consortium partner), the complete control and SCADA-system, and the MV switchgear. During the commissioning phase, the strict South African grid code describing the required behavior of a connected generator during system disturbances was also successfully implemented. The new power station will produce about 25 GWh of renewable energy per year.