| 摘要 |
A method and an apparatus for cleaning sulphurdioxide-containing gas, such as flue gas, are disclosed. In the method, the sulphur-dioxide-containing gas (1) is treated in a scrubber (2) with a washing liquid (3) which is circulated in a primary circuit (5). From the primary circuit (5), a partial flow is drawn off through a conduit (11) to a secondary circuit (12) for regeneration by means of the so-called indirect lime method. The invention is distinguished by a cooling circuit (25) which is connected to the secondary circuit (12) and in which a partial amount of washing liquid drawn off from the secondary circuit is treated by cooling in a cooling tank (27) to a temperature below 30 DEG C, preferably below 5 DEG C, for the precipitation of sodium sulphate. After the separation of precipitated sodium sulphate, the washing liquid is further treated in a tank (32) for the precipitation of more sulphate by the addition of a calcium-ion source (33), preferably consisting of calcium carbonate sludge from the secondary circuit (12). After the separation of precipitated calcium sulphate, the treated liquid now having a reduced sulphate content below about 300 mg/l is drawn off from the cooling circuit (25). <IMAGE> |
