Large storage tanks may require mixing to achieve homogeneity of
contents for several
reasons: prior to sampling for mass balance purposes, for blending in
reagents, for suspending
settled solids for removal, or for use as a feed tank to a process.
At Oak Ridge National
Laboratory, mixed waste evaporator concentrates are stored in
∼190-m3 (50 000-gal) horizontal
tanks, about 3.7 m (12 ft) in diameter and 18 m (60 ft) in length.
This tank configuration has
the advantage of permitting transport by truck and therefore
fabrication in the shop rather
than in the field. A survey of the literature revealed no
information on mixing large storage
tanks with length-to-diameter ratios greater than 2. Jet mixing
experiments were carried out
in two model tanks: a 0.87-m3 (230-gal) Plexiglas tank
that was ∼1/6 linear scale of the
actual
waste tanks and a 95-m3 (25 000-gal) tank that was about
2/3 linear scale of the actual
waste
tanks. Mixing times were measured by the use of a sodium chloride
tracer and several
conductivity probes distributed throughout the tanks. Several jet
sizes and configurations were
tested. In the 0.87-m3 tank, jet diameters of 0.016,
0.022, and 0.041 m (0.62, 0.87, and 1.61 in.)
were used. In the 95-m3 tank, jet diameters of 0.035
and 0.049 m (1.38 and 1.93 in.) were used.
One-directional and two-directional jets were tested in both
tanks. Mixing times for each tank
were correlated with the jet Reynolds number and for the two tank sizes
using the recirculation
time for the developed jet.
Nitroeen oxide removal efficiencies of up to 97% were obtained in tests using
R. M. COUNCEcolumns-packed with Intalox saddles. These studies were conducted at atmospheric pressure with water as the scrub solution and nitrogen oxide feed concentrations of up to 10%. A mathematical model based on mass-transfer, kinetic, and equilibrium data is presented; calculated removal efficiencies using this model agree Consolidated Fuel Reprocessing Program Oak Ridge National Laboratory Oak Ridge, TN 37830 very well with ihe experimental data. and J. J. PERONA
SCOPEExperiments were conducted to evaluate the aqueous absorption of NO, at atmospheric pressure and 298 K in towers packed with 6 and 13-mm Intalox saddles. The feed NO, partial pressure was varied from 0.01 to 0.10 atm; the scrub liquor was
Sodium triacetoxyborohydride (STAB) is a common reducing agent with potency that degrades over time and is not uniformly assigned. A simple assay based on an aldehyde reduction has been developed to determine the active borohydride content of this reagent. The HPLC assay yield of a salicylaldehyde reduction has been shown to accurately determine this potency and has been validated against the H 2 evolution method as well as yields obtained from a reductive amination. The use of these assay data to adjust the STAB charge as well to optimize a reductive amination has been demonstrated.
A mathematical model was developed for a sieve-plate column utilizing kinetic and equilibrium constants from the literature. The model adequately represents the effects of gas and liquid flow rates and feed gas composition on conversion as determined experimentally in a three-plate column. The concentration of HNOz in the scrubber liquid was shown to affect conversion strongly.
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