Hg Removal — [MRCS] Mercury Re-Emission Control System
The Purpose of the MRCS is to inhibit re-emission of mercury from the wet FGD [WFGD] liquor and thereby increase the total mercury captured and retained in the FGD system. Mercury re-emission can occur when soluble Hg+2 reacts via various mechanisms in the wet FGD liquor and is reduced to insoluble Hg, which then re-enters the gas phase and is emitted with the FGD outlet flue gas. The MRCS will inject an additive such as Powered Activated Carbon (PAC) into the WFGD slurry to absorb and sequester oxidized mercury before it can be reduced to the elemental form and re-emitted.
This modular process is based on the incorporation of the Vacucam® Ejector Mixer Slurry Process to provide the most efficient dust free mixing of the hydrophobic PAC product with water.
Two process options are available to meet any plant capacity and provide the most efficient use of plant logistics. All processes provide for dry material storage and conditioned feed to the slurry process. The Vacucam® Ejector Mixer Slurry Process is capable of delivering slurry with up to 10% solids to one or multiple scrubbers. A single system can produce ample slurry into storage tank(s) and a second unit would be provided for stand-by.
Option 1: PAC Storage | Single Pass PAC Slurry / Delivery Process | Injection Control
The skidded, packaged, single pass slurry process module is located underneath the silo discharge. It conveys PAC power directly from the batch weigh hopper with Air-Cone® discharge, slurries the PAC with water and discharges the slurry into a day tank. The finished slurry is pumped from the day tank to one or multiple injection points on a controlled basis. Slurry batches are produced on demand to maintain a setpoint level in the day tank.
Process Flow Schematics –Multiple Injection Control for Single Scrubber
Option 2: PAC Storage | Single Pass PAC Slurry | Direct Batch Slurry to Multiple Scrubbers
The skidded, packaged, single pass slurry process module is located underneath the silo discharge. It conveys PAC powder directly from the batch weigh hopper with Air-Cone® discharge and slurries the PAC with water. The finished slurry is pumped from the in-line slurry tank directly to one or multiple scrubbers. A level transmitter controls the VFD on the transfer pump to enable slurry batches to be produced on demand.
Process Flow Schematics –Injection Control for Multiple Scrubbers
Utilizing the VACUCAM® Ejector Mixer Slurry Process for producing PAC slurries offers major benefits for FGD in Power Plants that cannot be achieved with traditional mechanical mixers. The Systems are typically designed for single pass or batch processing of up to 10% solids. The VACUCAM® Ejector Mixer units represent the heart of the process, providing major benefits for PAC slurries feed to scrubbers.
- No Moving Parts
- no mechanical conveyors
- no pneumatic conveyors
- Low Maintenance
- Low Energy
- Efficient Dispersion and Mixing for high yeld process reaction
- Total Dust Control
- Rapid Start/Stop w/high capacity for total automation of slurry feed.
- Provide System Redundancy within one system. One system can support redundancy for second scrubber.