| abstract |
Extruded pellets comprising a majority of activated carbon particles and an organic binder provide improved performance when processed through tumbling equipment while the pellets are in their "green" state, i.e., pellets which are fresh off the extruder and contain activated carbon, binder, and water and have not been subjected to any thermal processing (drying). The tumbling action both smoothes the pellets (by closing any cracks and greatly improving appearance) and increases the density of the pellets, e.g., by increasing particle density and reducing voids between the pellets. Improved performance results from an ability to increase the weight of carbon pellets which can be packed into a fixed volume and thereby increase the volumetric working capacity of the bed for adsorbing/desorbing vapors. Another benefit is to greatly reduce the levels of dust associated with the carbon, both the initial dust and the dust of attrition. |