THE INFLUENCE OF PRESSURE ON THE BEHAVIOUR OF OIL SHALE CARBONATES
Tallinn Technical University
Thermal Engineering Department
| The utilization of solid fuels with high carbonate content
in mineral matter has some peculiarities, specially at burning in pressurized conditions. In the
combustion process the sulphur oxides are usually captured by the addition of limestone (CaCO3)
or dolomite (CaMg(CO3)2) into the com-
bustor. In the case when the fuel mineral matter itself contains carbonates, no additional impurities are needed to capture sulphur oxides from flue gas.
The carbon dioxide partial pressure in the flue gas has a significant influence on the fuel mineral matter behaviour and sulphur dioxide capturing mechanism. The CO2 partial pressure in the flue gas has also remarkable influence on the fuel heating value and carbon dioxide emission. Estonian oil shale is a fuel that itself contains a considerable amount of carbonates. Nowadays Estonian oil shale is utilized only in power plants using pulverized firing (PF) technology. Utilization of oil shale as solid fuel with high content of carbonates by pressurized fluidized bed combustion (PFBC) tech-
nology has some advantages.
Burning Estonian oil shale in atmospheric pressure combustors the carbonate decomposition rate is in the range 0.85-0.98. According to the theoretical calculations the carbonate decomposition rate should be much lower burning oil shale in pressurized conditions.
The aim of this paper is to investigate the behaviour of the fuel carbonates in pressurized combus-
tion conditions, experimental determination of the carbonate decomposition rate and its influence on the fuel heating value and carbon dioxide concentration in the flue gas. For these purposes the laboratory pressurized combustion facility was erected in Thermal Engineering Department of Tallinn Technical University.