Eskom’s new Kusile Power Station in Witbank, Mpumalanga, is set to benefit from the energy-efficiency of IWC’s patented glass fibre reinforced plastic (GRP) fan stacks, four of which have been manufactured for one of the station’s mechanical induced-draft cooling towers.  

By incorporating the flared-diffuser design, which has a slightly tapered exit cone and a well-rounded inlet bell, these GRP fan stacks reduce the amount of energy needed to power the 9.15m axial fan, resulting in significant energy saving when compared to conventional fan stacks.  

Comments Roger Rusch, CEO of IWC, “The flared fan stack design significantly reduces velocity pressure at the exit of the fan stack when compared to that of the throat (the ring in which the fan operates). Since the quantity of air is the same throughout the fan stack, the recovery of velocity pressure is converted into static pressure “regain", which lowers the total pressure requirements of the fan, thereby reducing its overall power consumption compared to conventional unflared fan stacks.  

The fibreglass fan stacks will also deliver the added benefit of exceptional corrosion resistance, excellent impact-and-dent resistance, and easy maintenance, ensuring long-lasting performance.”

The fan stacks, which took 12 weeks to manufacture at IWC’s facility in Isando, Gauteng, measure 10.74m in base diameter, 9.23m in cylindrical diameter, 10m in flared diameter and 5m in height. It will now take IWC approximately four weeks to install the fan stacks on site.  

In 2012, Eskom awarded IWC the contract to supply two, four-cell mechanical induced-draft concrete cooling towers for the Kusile Power Station. The latest fan stacks are for the second cooling tower, with IWC having already completed installation of the fan stacks in the first cooling tower. IWC has provided the same fan stacks on the auxiliary plant cooling towers for ESKOM’s Medupi Power station.

These cooling towers are part of the Kusile Power Station’s auxiliary cooling system and supply cooling water primarily for the turbine and boiler plant auxiliaries as well as compressor cooling and certain other items of the plant. Each of the cooling towers is designed for a flow rate of 16 000m³/h and has a heat rejection of 126 MW.  

The Kusile Power Station is scheduled to commence commercial operations in the second half of 2017. The power station will comprise six units, each rated at an 800 MW installed capacity for a total capacity of 4 800 MW. Once completed, Kusile will be the fourth-largest coal-fired power station in the world.