The ash balance and the extent of carbonate decomposition (ECD) for circulating fluidised-bed (CFB) boilers depending on oil shale lower heating value (8.5 and 11.1 MJ/kg) were analysed. As for the ash balance, ash mass flow rates (kg/s) for each ash separation port were determined. In calculations the ECD methodology developed at the Department of Thermal Engineering (DTE) on the basis of ash composition was used. Changes in the boiler ash balance occurred when firing oil shale of different quality. Additionally, the reduction of the CO2 emission by 7% and of the total ash mass flow by 23% was obtained when firing upgraded oil shale instead of low-grade oil shale.
1. Hotta, A., Parkkonen, R., Hiltunen, M., Arro, H., Loosaar, J., Parve, T., Pihu, T., Prikk, A., Tiikma, T. Experience of Estonian oil shale combustion based on CFB technology at Narva Power Plants // Oil Shale. 2005. Vol. 22, No. 4S. P. 381–397.
2. EVS-EN 12952-15:2003, Water-tube boilers and auxiliary installations – Part 15: Acceptance tests.
3. Ots, A. Oil Shale Fuel Combustion. – Tallinn, 2006, 833 p.
4. Arro, H., Prikk, A., Pihu, T. Calculation of CO2 emission from CFB boilers of oil shale power plants // Oil Shale. 2006. Vol. 23, No. 4. P. 356–365.
