Power generation, metallurgy, oil refining are just some industries where removal of sulfur dioxide (SO2) from flue gases of industrial combustion is practiced.
Common methods for SO2 removal are:
- Wet scrubbing using a slurry of alkaline sorbent, usually limestone or lime, or seawater to scrub gases;
- Spray-dry scrubbing using similar sorbent slurries;
- Wet sulfuric acid process recovering sulfur in the form of commercial quality sulfuric acid;
- SNOX Flue gas desulfurization removes sulfur dioxide, nitrogen oxides and particulates from flue gases;
- Dry sorbent injection systems that introduce powdered hydrated lime (or other sorbent material) into exhaust ducts to eliminate SO2 and SO3 from process emissions.
SO2 is an acid gas, and, therefore, the typical sorbent slurries or other materials used to remove the SO2 from the flue gases are alkaline. Widespread sorbents used in these processes are limestone slurry and hydrated lime slurry.
In both cases rugged abrasion resistance mixers are required to produce those slurries. Mixtec manufacturers autoclave cured soft natural rubber lined wet end agitators to guarantee many years of low wear service in abrasive environments.
The absorbers downstream may host horizontal or vertical mixers. The harsh environment of an FGD absorber requires special mixer execution. Mixtec designs efficient heavy-duty impellers that deliver high process results preventing gypsum scaling, and resist the corrosion-abrasion media. Rugged mechanical seals are specifically selected for FGD service while the seal shutoff device allows for maintenance of the agitator without interruption of the adsorber operation.
When wet sulfuric acid process is applied, for example in metallurgical smelters, the end product of the process is concentrated sulfuric acid. Usually, the acid is sold, but in some cases, sale it is not economically feasible, for example to high transportation expenses. Then the acid has to be neutralized.
Another neutralization application is acid mine drainage where the acidic mine water is treated with milk of lime. In both cases Mixtec has extensive experience designing both lime milk preparation mixers and neutralization mixers. The picture depicts a large acid mine drainage water treatment plant in Germiston, Gauteng (South Africa), which contains a comprehensive mixing system of 53 specialized Mixtec mixers in special corrosion / abrasion resistant execution.
