1321 - Office of Legacy Management - U.S. Department of Energy

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FDF Subcontract No. 98SCOoooO1
IT Project No. 773481
Desaiption ofoperatioa & process
Issue Date: 2/13/98 Rev. B
pump (P-5002). Entrained water from the venturi is removed from the off-gas in the mist
eliminator and drains to the venturi sump (T-5001). Excess scrubbing water is purged fiom the
venturi sump and pumped to the oil/water separator.
Off-gas from the mist eliminator flows into the wet electrostatic precipitator (WESP) (S-5005)
for the removpl of residual particulate. A small stream of water is continuously sprayed into the
off-gas as it enters the WESP. Water and particulate collected in the WESP are drained to the
venturi sump and pumped to the oiVwater separator.
The off-gas from the WESP is slightly reheated in the electrically heated off-gas reheater
(E-5004) in order to prevent any condensation in the HEPA filters or carbon hrber. The
induced-draft fan (B-5001) is used to pull the off-gases through the system from the dryer
through the WESP, keeping the entire system under negative pressure so that any leakage is into
the system. The HEPA filters are mounted in parallel with only one being used at a time, with
the other on standby or being replaced as necessary. The HEPA filters remove particulate greater
than 0.3 microns that may have passed through the WESP. The carbon adsorber (S-5006)
removes organic vapors which have not been condensed and removed by the other gas cleaning
system components. The clean off-gas from the system is released to the atmosphere through the
vent stack (X-5001). Point Source Emission estimates are discussed in the Point Source
Emission section of this design package.
An optional Thermal Oxidizer (F-5001) is shown in parallel configuration with the carbon bed
and may be operated in lieu of the carbon bed in the event that volatile organic compound (VOC)
concentrations cause rapid exhaustion of the carbon bed. The Thermal Oxidizer provides an
effective means for the treatment of VOCs in the gas stream.
The condensed and purged liquids from the GCS are directed through the oiYwater separator
shown on PFD D-70- 10-00 1. The water fraction will be routed to the WTS influent tank for
pretreatment prior to discharge to the BSL and the AWWT system. The oil fraction will be
handled in the following manner. If the characteristics of the oil fraction do not meet CDF WAC,
it will be turned over to FDF for subsequent handling and disposal. Otherwise, the oil fraction
will be utilized for dust suppression at the dryer discharge conveyor, or blended directly back
into the waste for disposal along with the other pit waste at the CDF.
KN/39S7/WPRAP/E2E2.W-20-98(909 myDl/NE
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