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| Powder | Granular | Pellets | Impregnated Carbon |
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Pellet Carbons
The pelletized activated carbons are generally classified according to their diameter:
- 0.8 mm: Silcarbon 0.8supra
- 1.5 mm: Silcarbon SIL-15 extra, SC15,
- 2 mm: Silcarbon SIL20
- 3 mm: Silcarbon SIL-40-3S
- 4 mm: Silcarbon SIL-40, SC-40, SC-44 and FT40spezial
Application Fields:
- 0.8, 1.5 or 2 mm pelletized activated carbon:
· Waste water
· Purification of chemicals
· Air purification (small filter units)
· Aquarium water
· 3 or 4 mm pelletized activated carbon:
· Air and gas purification
Air Purification
In many industrial processes toxic vapors and gases are emitted. Generally these toxic substances should not be emitted. The most frequent toxic substances in waste air are solvents, which are necessary for the production of materials for our daily life. For the separation of the solvents (mostly hydrocarbons, such as chlorinated hydrocarbons and CFCs), activated carbon has proved to be reliable because of its water-repellent character.
Air purification can be classified into waste air purification and solvent recovery according to the quantity and concentration of contaminant in the air. At high concentration, it might be cheaper to recover the solvents from the activated carbon (e.g. by means of steam). But if the toxic substances exist at a very low concentration or in a mixture, which can't be reused, 'one-way' pelletized activated carbons are preferred.
Application Methods
Pelletized activated carbons are applied in fixed bed adsorption units. The contaminated air flows through the stationary carbon layer in one direction (mostly upward). The operating characteristics for air and gas purification can generally be described as follows:
| Flow rate: Contact time: Height of fixed bed: |
0.1 - 0.5 m/sapproximately 0.1 - 0.5 seconds approximately 0.1 - 0.5 seconds at least 0.5 m, mostly 1 - 3 m |
The pressure drop over the filter bed is mainly dependent on the height of the activated carbon in the filter vessel, the size of the particles and the velocity of the incoming air. For a 4 mm pellet the pressure drop is depicted in the diagram below.
