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The Role of Dibasic Acid (DBA) in Wet Limestone

Flue Gas Desulfurization

FGD cost and performance are becoming increasingly important as emissions regulations

become more stringent. Long-term operating experience in full-scale limestone scrubbers

has established that organic acid additives can improve scrubbing efficiency, improve

reliability, and reduce operating cost. Organic acid enhanced wet limestone scrubbing is now

the flue-gas desulfurization process of choice for many utilities' retrofit and new scrubbers.

Operators of coal-fired boilers need FGD systems that are reliable, based on proven

technology, and meet environmental regulations at optimal power generation cost. Utilities,

technology vendors, and architectural/engineering firms are discovering that organic acid

additives can improve SO2-removal efficiency and offer a wide range of possible benefits,

including:

Lower operating expense through:

• Reduced liquid/gas ratio in wet scrubbers

• Less power consumption by slurry pumps

• Reduced limestone consumption

• Consumption of less expensive coal

Reduced maintenance costs through:

• Reduced scaling

• Reduced plugging

• Reduced exit gas corrosion

Flexibility to over-scrub

• Accumulation of additional SO2 credits for use or sale

• Allows for flexibility in fuel selection

Improved ability to handle swings in inlet SO2

Increased generating capacity (when previously limited by scrubber performance)

Reduced capital investment through:

• Equipment downsizing for new scrubbers

• Reduced investment in scrubber retrofits

Modeling1 shows that operational and maintenance costs of a wet limestone scrubber can

be reduced by about 2% (about $200,000/year) when using DBA, including the cost of

the DBAadditive. The increased SO2 scrubbing efficiency using DBAtranslates into about a

15% reduction in limestone use, a 1% reduction in steam, a 1% reduction in solid waste

disposal costs, and a reduction of about 17% in power usage. Payback time, based on SO2

credit prices of $200/ton, for the capital required to retrofit an existing wet limestone scrubber

for DBAaddition (storage tank, pump, piping) ranges from 5 months to about two years,

depending on operating strategy (i.e. maintain SO2 efficiency and reduce operating costs vs.

improve SO2 efficiency and profit from emission credits)1.

When installing a new scrubber, a design incorporating DBAadditive can lead to significant

capital cost savings. Modeling shows a capital cost reduction of 3% from reducing the

operational L/G ratio, which reduces the size requirements for tanks and pumps. The

decreased L/G operation allows for design of a smaller scrubber, yielding a 5% cost savings

compared to a wet limestone scrubber without DBA*.

1Modeling based on a 566 Mw boiler using eastern bituminous high-sulfur coal (3% sulfur,

12,720 BTU/lb heating value) and 90% SO2-removal efficiency using NETL Integrated Environmental Control Model (copyright Carnegie-Melon University). Emission credit

information is available from Argus Coal Daily.

* Consult your site’s environmental and engineering experts for permitting issues that may

apply to your facility.

Case studies of Plant Testing More than twenty years of commercial experience has demonstrated that INVISTADibasic Acid (DBA) can reliably and dramatically improce the SO2-removal efficiency of wet limestone

scrubbers. Because each scrubber is unique, the first step toward reaping the benefits of DBAis usually to run a test to determine the scrubber performance as a function of DBA

concentration in the scrubber.

For information on testing INVISTADibasic Acid in a wet limestone scrubber, please refer to

the document below. If interested, we are available to assist your facilitywith a trial to allow

you to further realize the benefits provided by INVISTADBA. Our technical experts can assist with planning the trial, analytical measurements and discussion of results. In addition, a

custom INVISTAtest trailer is now available for on-site plant trails. The tank provides portable

heated storage with controlled feed additional capability and allows for extended testing without the need for permanent facilities.

Testing INVISTADibasic Acid (DBA) in Wet Scrubbers.pdf (187 kb)

Flue Gas Desulfurization Brochure

For more detailed information about the use of INVISTADBAin Flue Gas Desulfurization,

please contact us at (800) 231-0998 and we will be happy to send you a copy of the

brochure “The Role of Organic Acids in Flue Gas Desulfurization”.

The documents are in PDF format and require Adobe Acrobat Reader. If you do not have the Adobe Acrobat Reader, you can get a free programmhere. Adobe Acrobat Reader

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