Granular loads

Fig. 4.3. A rotary drum dryer, kiln, incinerator, or furnace transports granular loads left to right) by gravity and rotation, counterflow to the burner gases and induced air. Parallel flow orco-current flow (fig. 1.10) can be used with some load materials and processes.

Herreshoff multilevel furnace = a vertical cylindrical furnace with many circular hearths attached to a central vertical drive shaft, and with plows to move granular load material across each hearth to expose all particles to furnace gases and to cause them to eventually drop to the next hearth level. Burners fire horizontally below and between the hearths. Used for drying sewage sludge, and for drying and pyrolizing ores. 

Most commercial adsorbents for gas-phase appHcations are employed in the form of pellets, beads, or other granular shapes, typically about 1.5 to 3.2 mm in diameter. Most commonly, these adsorbents are packed into fixed beds through which the gaseous feed mixtures are passed. Normally, the process is conducted in a cycHc manner. When the capacity of the bed is exhausted, the feed flow is stopped to terminate the loading step of the process, the bed is treated to remove the adsorbed molecules in a separate regeneration step, and the cycle is then repeated. 

Granular catalyst resin loaded in corrugated sheet casings Dimethyl acetals of formaldehyde Zhang et al., Chinese Patent 1,065,412 (1992)... 

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

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. 

The filter application is typically applied to handling streams containing less than 100 to 200 mg/Liter suspended solids, depending on the required effluent level. Increased-suspended solids loading reduces the need for frequent backwashing. The suspended solids concentration of the filtered liquid depends on the particle size distribution, but typically, granular media filters are capable of producing a... 

Granular bed filters are used in porcelain enameling wastewater treatment to remove residual solids from clarifier effluent (sedimentation effluent or flotation effluent). Filtration polishes the effluent and reduces suspended solids and insoluble precipitated metals to very low levels. Fine sand and coal are media commonly utilized in granular bed filtration. The filter is backwashed after becoming loaded with solids and the backwash is returned to the treatment plant influent for removal of solids in the clarification step.10-12... 

The activated carbon is often chosen as granular carrier and is referred to as granular activated carbon (GAC) or biological activated carbon (BAC). This support is characterized by a strong propensity to adsorb the dyes and is a good candidate for biofilm formation, because of its natural organic matrix. The marked propensity to adsorb dyes contributes to increase the tolerance to shock loadings. In fact, under transient conditions the free surface of the AC acts as a temporary buffer for the dye, which is eventually released as dye disappears. 

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. 

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