Granular carbonization

Pulsed beds of ac tivated carbon are used in water and wastewater treatment systems. The adsorber tank is usually a vertical cylindrical pressure vessel, with fluid distributors at top and bottom, similar to the arrangement of an ion exchanger. The column is filled with granular carbon. Fluid flow is upward, and carbon is intermittently dis-... 

The plot in Fig. 13 shows the bleed emissions that were measured after a 24 hour soak. Two eanisters were tested, one loaded with a wood granular carbon with a mean particle diameter of 1.27 mm, the second with a wood pellet carbon with a mean particle diameter of 2.10 mm. Both carbon samples had equal BWC of 11.4 g/lOOml. Although both earbons had the same BWC, the larger pellet earbon had lower bleed emissions. These diffusion results are expected in light of Pick s Law. 

Monolithic carbons may also be manufactured in finished form fi om PVDC as has been done by Quinn [18]. The porosity and density compare favourably with those of conventional granular carbons and the Sutcliffe Speakmann monoliths but the manufacturing process is not easy to scale up from the laboratory to commercial levels. The properties, (including K and n from the D-A equation) are compared in Table 3 below, taken from Critoph [4]. 

To increase rates of adsorption and decrease the time necessary to complete the isotherm, it is recommended that the granular carbon be pulverized so that 95 wt % will pass through a 325-mesh screen. Such pulverization does not significantly increase the surface area. The increase in the surface area, in most cases, is less than 1 percent, as the vast majority of surface area is contributed by the pore walls rather than by the external surface of the carbon particles. 

The performance of two or more carbons in the same application can be compared by examining their isotherms. Usually, granular carbon with the higher 3)/m value would be preferred for an application. 

Of particular note we found improved selectivity with certain extiuded carbon supports versus granular carbons, graphitic carbons, metal oxides (titaiua and zircoitia), and carbon treated with zircoiua. Data shown in Figures 34.6 and 34.7 were generated in batch experiments using Ni/Re as catalytic metals. In Figure 34.6a,... 

Millions of gallons per day Suspended solids Granular carbon Not including pH adjustment eNot including brine disposal. 

Catalyst Charge was 40ml (18.31 g) of a 2.5%Rh2.5%Re/Engelhard 95% CTC granular carbon support (20X50 mesh particle size)... 

Intimate mixtures with carbon or phosphorus may ignite or explode [1]. Other readily oxidisable materials (probably antimony, arsenic, boron, sulfur, selenium) also form explosive mixtures [2], Use of finely powdered carbon, rather than the granular carbon specified for a reagent, mixed with sodium peroxide caused an explosion [3],... 

The pressure drop of a one liter canister during an ORVR event was studied. Canisters were filled with a pelletized carbon with a mean particle diameter of 2.1 mm and a coal granular carbon with a mean diameter of 1.3 mm. During the canister loading of 50 grams/min the canister with the 2.1 mm pellet had a pressure drop that increased from 0.35 to 0.55 kPa (1.4 to 2.2 inches of water). The granular carbon experienced a pressure drop of 0.98 to 1.5 kPa (3.9 to 6.0 inches of water) under the same conditions. 

Canister working capacity was studied for a 1.27 mm mean diameter granular versus 2.1 mm mean diameter pellet carbons of equal BWC. Under the ORVR loading conditions the granular carbon had a 6-12% higher GWC. However, the high pressure drop of the granular carbon would make it very difficult to use in an ORVR system. 

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