Untersuchungen zur Alkalireinigung bei der Zirkulierenden Druckaufgeladenen Wirbelschichtfeuerung der 2. Generation zur Minimierung des Risikos für Heissgaskorrosion

A necessary prerequisite for the implementation of 2 nd Generation Circulating Pressurized Fluidized-Bed Combustion (2 nd -Gen.-CPFBC) is the decrease of the alkali concentration in the hot flue gas to values compatible with the gas turbine blading (<<1 ppm). Thermodynamic calculations and laboratory experiments reveal that alumosiliceous sorbent materials with an Al 2 O 3 /SiO 2 ratio of about 0.17 have the highest potential to fulfil these demands. Up to 20 Mol-% of alkali oxides can be bound in these alumosilicates by the formation of albite and orthoclase. Laboratory experiments with a flow channel reactor coupled with a High Pressure Mass Spectrometer (HPMS) related to the sorption kinetics show that the alkali concentration in the hot flue gas can be reduced to values much lower than 100 ppb by suitable alumosilicates. Thermodynamic calculations based on the experimental results were used to estimate the risk of high temperature corrosion of the turbine blading of a CPFBC-2 nd -Gen. The calculations show that there is only a theoretical risk of hot corrosion in a small temperature range using lignite mainly depending on the sulphur content of the coal.