Residue Transport and Dumping Modern Residue Transport and Dump Systems for Power Plants
Modern residue removal systems allow for a reliable, economic, and environmentally friendly transport of the huge volumes to be handled in large-scale coal fired power plants. Here in particular, tube conveyors in conjunction with shiftable conveyors and mobile spreaders offer reliable solutions.
Large coal fired power plants are seen as fast and reliable solutions to the raising energy demand of fast growing economies. With plant capacities often up to 4000 MW not only the continuous supply of fuel in the right quality and quantity becomes a challenge. Also, the reliable, economical and environmentally friendly residue transport and disposal calls for new solutions to cope with the large material volumes produced. Continuous transport and dumping systems are often the preferred choice. Reliable solutions can be offered by combining proven technologies from bulk materials handling such as curved or tube conveyors with dumping technologies from open pit mining. Examples of residue handling systems in Bulgaria, South Africa and Russia are compared, highlighting the flexibility of such systems.
600 million Indians in the dark, power shortages in South Africa lifting Platinum prices, the appetite for power seems to be insatiable in many regions of the world (Fig. 1). Despite on-going discussions on greenhouse gas emissions new giant coal fired power plants are often the short term answer to power shortages.
The topic is reflected in a plan to build at least ten Ultra Mega Power Plants in India, the construction of the first plants being on its way, or in the current construction of the new Kusile and Medupi (each approx. 4800 MW) power plants of Escom in South Africa.
On the other side, existing power plants in Eastern Europe are upgraded or replaced to meet the growing power demand and new economic and environmental standards in this region. The first dry ash handling system will be installed in Russia in the existing 3800 MW power plant Reftinskaya of Eenel OGK-5 near Yekaterinburg, replacing an outdated hydraulic system. The high ash coal for this power plant is sourced mainly from the Ekibastus coal mines in Kazakhstan, with a combined capacity of approx. 40 million tonnes per year one of the largest coal mines in the world.
Another good example for the replacement of old technology by a most modern plant is Maritsa Iztok-1, the first large-scale power plant built in Bulgaria since 1990 and the cleanest coal fired plant in Bulgaria, meeting the environmental standards of the world-bank. The power station belongs to the 3000 MW Maritsa Iztok complex located in south-central Bulgaria, one of the largest power plant complexes in South Eastern Europe, covering about 40 per cent of Bulgaria’s power consumption. It is located in the Thracian plain about 100 km from the Black Sea, In 2006, the AES corporation started the construction of the two 335 MW units.
A challenge to all these plants is not only the continuous supply of quality fuel but also the reliable and environmentally friendly removal of the process residues. With old technologies the ash was often transported by trains to the waste dump or pumped as wet ash to hydraulic dumps. The latter, being huge settlings ponds, often posed a burden to the environment, not acceptable any more today. Main characteristics of the three systems analysed are shown in Table 1.