Dl. Tomasko et al., PILOT-SCALE STUDY AND DESIGN OF A GRANULAR ACTIVATED CARBON REGENERATION PROCESS USING SUPERCRITICAL FLUIDS, Environmental progress, 12(3), 1993, pp. 208-217
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Categorie Soggetti
Environmental Sciences","Engineering, Civil","Engineering, Chemical
A technology which has great potential for environmental control and w
aste remediation is contaminant removal and separation with supercriti
cal fluids (SCF's) or supercritical fluid extraction (SFE). Pressure t
uning of solvent power allows SCF processes to adapt to a wide variety
of small batch oriented separations typified by environmental cleanup
operations. The ability of supercritical CO2 to extract model contami
nant compounds from GAC and subsequently drop out most of the contamin
ant in a liquid phase has been investigated in a pilot scale apparatus
. Typical desorption profiles indicate an 85% removal of the compound
from the carbon which allows for reuse. The desorption results have be
en interpreted with a generalized desorption-mass transfer model. The
results of the pilot plant studies have been applied to the design of
a fixed-site GAC regeneration unit consisting of a three-element desor
ber with two-stage flash separation. Optimization of the process cente
rs around minimizing the cost of recycling the SCF through an efficien
t recompression scheme and cycle configuration in the desorber unit. A
n economic evaluation shows a processing cost of 10.6cent/lb (23cent/k
g) GAC which compares favorably with thermal regeneration and incinera
tion. This non-destructive process allows re-use of the GAC while main
taining a high adsorbate capacity, which reduces carbon replacement co
sts and significantly decreases the need for carbon disposal by landfi
ll or incineration.