LEAD-TRIM OPERATION EXPLAINED
ADSORPTION PROCESS
In a Lead-Trim Process Design (also sometimes called “Lead-Guard” or “Lead-Lag” Operation) There are two adsorber vessels, or Beds “A” and “B.” The beds are connected with a flow manifold requiring a 6-valve sequence that makes it possible to operate flow through:
(1) First Bed A, then Bed B
(2) Either bed alone
(3) First Bed B, then Bed A.
PROCESS STEP |
Fluid Flow Sequence |
INITIAL OPERATION |
A then B |
DURING CHANGE-OUT of A |
B alone (A is off line) |
AFTER CHANGE-OUT of A |
B then A |
DURING CHANGE-OUT of B |
A alone (B is off line) |
AFTER CHANGE-OUT of B |
A then B |
The sequence repeats.
The system never has to shut down to change out an adsorber.
WHY SERIES-FLOW OPERATION?
THE BENEFIT
In all adsorption systems, there is a mass transfer front, or zone (MTZ) in the adsorber. The length of this front depends on many variables, such as: type of contaminant being removed, viscosity, pressure, & temperature of the process fluid being treated, & the characteristics of the adsorbent itself. Often, the MTZ takes up a large portion of the adsorbent bed. The portion of adsorbent behind the MTZ is used to 100% of its equilibrium loading for the contaminant, according to the adsorption isotherm. The portion of adsorbent in the MTZ is used to only ~ 50% of its equilibrium capacity for the contaminant. With Lead-Trim Operation, this 50% loaded MTZ can be pushed out of the Lead Bed into the Trim Bed, allowing the Lead bed to reach 100% of its adsorption potential for removing the contaminant. The Trim bed then becomes the next Lead Bed.
BENEFITS of Lead-Trim Operation include:
(1) REDUCES COSTS for time-averaged adsorbent purchase & disposal Running the Lead Bed to full saturation with contaminant means it lasts longer.
(2) BEST PURITY Treated Fluid: the Trim bed is only lightly loaded with contaminant.
(3) FASTER APPROVAL: Environ. regulators like Lead-Trim: minimizes potential leakage.
(4) CONTINUOUS OPERATION: No unscheduled shut-down to change-out a bed.
CAUTION:
Wet activated carbon removes oxygen from air. Thus, an asphyxiation hazard exists inside enclosed spaces containing activated carbon. Use appropriate safety precautions when entering vessels or other enclosed spaces containing activated carbon.
MERSORB® mercury adsorbent is a trademark of Nucon International, Inc. (NUCON®) for impregnated activated carbons used to remove mercury from gases and liquids. Information presented herein is believed to be accurate and reliable but does not provide any guarantee or warrantee by NUCON® or by Selective Adsorption Associates, Inc.
AntiMercure® is a Registered Trademark of Selective Adsorption Associates, Inc. for its Process for removing mercury from water. AntiMercure® is a Trademark of Selective Adsorption Associates, Inc. for its Systems for removing mercury from water.
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