If you find yourself with any of these questions…

Can I really expect to use my wet FGD to economically and reliably achieve mercury MATS

compliance?

Is there enough time to implement additive-based solutions?

My company has started down the activated-carbon-injection path. Is it too late to consider this

alternate approach?

..then call us now. Yes, you have time.

The additive-based solutions require relatively small and simple capital projects.

A feasibility analysis of an additive-based solution can be done quickly based on your FGD inlet

mercury load, the fraction of the inlet mercury oxidized, properties of the coal, and your

equipment configuration.

With an understanding the multiple steps and the importance of mercury inventories, elemental-

mercury saturation, and the mercury material balance requirements, demonstration trials can be

readily done to confirm the results of the feasibility analysis.

The Three-Step Method for Mercury Emission Control in

Wet Flue Gas Desulfurizers

Babcock and Wilcox Power Generation Group 1970 Glenhurst Drive, NW Lancaster, OH 43130-8181 office: (614) 834-3740 cell: (614) 716-9952 email: sfeeney@babcock.com

TDC, a Genesis Energy Company 8550 United Plaza Blvd Suite 401 Baton Rouge, LA 70809 Customer Service: 1-(800) 422-6274 – 24 hours/day Application Tech Support: (225) 938-9246 email: joe.stuart@genLP.com

Joe Stuart, Director of Commercial Development, TDC, LLC, a Genesis Energy Company

Engineer, manager, and entrepreneur with over 30 years experience developing and

commercializing a broad range of process technologies including sulfide-based

environmental applications as well as isocyanates, urethanes, methacrylates, and

alumina processes and manufacturing technologies. Current responsibilities include

commercialization of applications for sodium hydrosulfide and in particular

commercialization of B&W’s Absorption Plus Hg® technology.

Steve Feeney, Mercury Control Product Line Manager, Babcock and Wilcox Power

Generation Group

Business development manager with over 35 years experience with a worldwide leader in

power generation, boiler cleaning solutions and environmental control. Current

responsibilities include leadership for technologies associated with the capture and

ultimate removal of flue gas mercury, including activated carbon injection and B&W’s

patented Absorption Plus Hg® technology, which uses aqueous sulfide to precipitate

mercury from solution.

Air Quality IX Presentation-Brochure 10.23.2013

Step Process Step General

Techniques Specific Approach

mass transfer of mercury

oxidation halogen addition, SCR

mercury desaturation of the liquid

precipitation, carbon-capture

organic sulfide, inorganic sulfide, activated carbon

mercury removal from the system

water treatment of chloride purge

vendor solutions, bio-treatment, pH-swing precipitation, filtration + other

Mercury Emission Control on Wet Flue Gas Desulfurizers Mercury Re-Emission Suppression

The Path Forward with Re-Emission Suppression

Assumes the observed increase in elemental mercury in the flue gas across the wet FGD is the cause of excess mercury emissions. Therefore, one can reduce mercury emissions by inhibiting this increase across the wet FGD.

Mercury Emission Control on Wet Flue Gas Desulfurizers 3-Steps: Mass Transfer / Desaturation / Removal

The Path Forward with the 3-Step Method Questions, Answers, and Examples

Mercury re-emission suppression technology can only succeed if the

mercury material balance is incidentally satisfied.

1

2

3

Definition of Re-emission:

elemental Hg elemental Hg at stack at scrubber inlet

Objective:

Suppress the re-emission mechanism with additives or adjustments to scrubber chemistry.

>

How do I know the 3-Step Method can work for me?

If you can achieve sufficient oxidation of mercury at the inlet to the scrubber, then it can be absorbed and

removed in the solid and liquid discharges from the scrubber – not in the stack gas.

For example, an operator has 20 # Hg/TBTU at the scrubber inlet and can achieve 95% oxidation. By managing

the soluble mercury inventory in the scrubber to maintain sub-saturated Hg conditions, the operator can expect

to reliably operate near 1 # Hg/TBTU, below the MATS limit of 1.2 #/TBTU on a 30-day average.

But my company has done re-emission and oxidation additive trials which were “inconclusive”. Why is the 3-

Step Method any different?

Removing mercury from flue gas is a multi-step process. Testing one step at a time with oxidizer or re-emission

additives without sufficient understanding of the other step(s) can readily lead to trials generating no useful

information.

FGD additives are too expensive. My company is getting bids on activated carbon injection systems. What are

we missing?

(1) Required chemical dosages are readily overestimated in trials which fail to account for the multi-step

process. The 3-step method allows one to readily establish the minimum dosage rate for reliable operation.

(2) Proprietary additives have been heavily promoted in the industry. Operators have been steered away from

generic additives where they could save 80% or more compared to proprietary products based on the

difficulty of “re-emission suppression”.

(3) The combined effect of high dosages and high unit costs have driven the perceived cost of FGD-additive

systems for mercury removal by as much as a factor of 10 even in systems which are excellent candidates for

low-cost, additive-based solutions.

How does this 3-step method explain what has been previously described as “mercury re-emission”?

Observed “mercury re-emission” is actually just elemental mercury which is stripped from the FGD slurry by flue

gas. Sufficient elemental mercury is stripped from the slurry to satisfy the material balance around the wet FGD at

any point in time. If your wet FGD fails to provide sufficient capacity for mercury to leave the scrubber in a non-

stack-gas stream, then it must leave in the stack gas. The mercury in the stack gas will be mostly elemental

because elemental mercury has both a higher vapor pressure and a lower solubility than oxidized forms of

mercury in the scrubber slurry liquid.