Pellet Activated Carbon

Extruded Cylindrical Form for Gas Phase Service

SorbiTech Pellet Activated Carbon is the gas phase counterpart of the granular grade used in water duties. SorbiTech manufactures the pellet from a coal or coconut shell precursor that is carbonised, blended with a binder, extruded into 3 mm or 4 mm cylinders, then steam activated at controlled temperature. The result is a developed micro and meso pore network on a surface area of 1050 to 1200 m²/g and a hardness above 95 percent.

The cylinder geometry gives a 30 to 50 percent lower pressure drop than the equivalent granular grade at the same bed length, which is the deciding parameter in gas service where the blower or compressor energy is recurring.

Solvent Recovery and Vapour Treatment

Solvent recovery vents from coating, printing, and chemical processing carry volatile organics at concentrations between 100 and 10,000 mg/m³. The SorbiTech solvent recovery unit passes the vent through a SorbiTech carbon bed that captures the organic, regenerates the carbon with low pressure steam, condenses the recovered solvent, and returns it to the process at a recovery rate of 95 percent or higher.

Vapour recovery units on tank farms, loading racks, and railcar terminals follow the same principle, with the vent of the loading operation routed through twin carbon beds operated out of phase. The recovered hydrocarbon offsets the unit capital within months for high throughput terminals.

Impregnated Grades for Trace Removal

For trace species that simple physical adsorption cannot retain, the carbon is impregnated with a chemical promoter. SorbiTech supplies the standard impregnated grades to SorbiTech specification:

• Potassium hydroxide impregnated for acid gas removal
• Sulphur impregnated for mercury guard beds in natural gas
• Triethylene diamine for radioiodine in nuclear applications
• Potassium iodide for hydrogen sulphide and mercaptan removal
• Phosphoric acid for ammonia removal

Bed Sizing and Service Life

Pellet carbon beds are sized by superficial velocity (typically 0.3 to 0.5 m/s in gas service) and by the contracted breakthrough time. A 1 metre bed depth at 0.4 m/s gives 2 to 5 second contact time, which suffices for most solvent recovery and vapour recovery duties. Service life ranges from 6 to 36 months depending on the contaminant load and the regeneration regime.

Forms and Supply

Manufactured to ISO 9001:2015 as 3 mm or 4 mm pellets, released against a certificate of analysis covering iodine number, hardness, moisture, and ash. Supplied in 25 kg bags or 500 kg big bags as standard media, inside a SorbiTech vapour recovery unit, or with a reactivation programme that holds carbon activity within design limits. Within the SorbiTech Group, pellet carbon is specified for vapour recovery on tank farms and gas phase guard duty; see refinery effluent, the refining sector, and the parent activated carbon family.