Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering Transport Technology
P.A.F. Witvliet Behandeling van steenkool: open opslag versus opslag in mammoetsilo's Masters thesis, Report 97.3.TT.4886, Transport Engineering and Logistics.
The world-wide use of coal has increased significantly over the past two decades. The international trade in thermal coal has increased from 40 million tons in 1978 to 245 million tons in 1995. This rise is mainly caused by an increasing number of power plants using coal as fuel for the heat-production. At this moment most power plants use open storage systems for the storage of coal. Systems with stockpiles storing one quality as well as blending systems for different qualities are used. Blending is applied to meet boiler specifications, environmental regulations and economical demands. The quality of the coal also has impact on the quality of residual products like gypsum and fly-ash.
The main disadvantage of open storage are the dust emissions. A possible solution to meet more stringent environmental demands is closed storage of coal in mammoth silo's. Besides eliminating the dust emissions from the stockpile the silo has other advantages. There are good possibilities for online blending and calorific and mass losses caused by the self-heating of coal are reduced. There is no negative influence of weather conditions on the quality of the coal and the use of land is a factor 2 to 3 less than for open storage systems with comparable storage capacity.
The mammoth silo is an attractive option for power plants needing storage capacity for one to two weeks of operation (max. 1100.000 tons). The main competing alternative in this case is the circular blending system. For larger storage capacities the combination of closed active storage with open passive storage is an attractive storage system in economical as well as in environmental respect.
Reports on Transport Engineering and Logistics (in Dutch)
