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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: |
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| Lower operating expense through: |
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Reduced liquid/gas ratio in wet scrubbers |
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Less power consumption by slurry pumps |
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Reduced limestone consumption |
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Consumption of less expensive coal |
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| Reduced maintenance costs through: |
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Reduced scaling |
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Reduced plugging |
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Reduced exit gas corrosion |
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| Flexibility to over-scrub |
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Accumulation of additional SO2 credits for use or sale |
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Allows for flexibility in fuel selection |
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| Improved ability to handle swings in inlet SO2 |
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| Increased generating capacity (when previously limited by scrubber performance) |
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| Reduced capital investment through: |
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Equipment downsizing for new scrubbers |
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Reduced investment in scrubber retrofits |
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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 DBA additive. The increased SO2 scrubbing efficiency using DBA translates 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 DBA addition (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 DBA additive 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*. |
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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. |
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| Case studies of Plant Testing |
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More than twenty years of commercial experience has demonstrated that INVISTA Dibasic 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 DBA is usually to run a test to determine the scrubber performance as a function of DBA concentration in the scrubber.
For information on testing INVISTA Dibasic Acid in a wet limestone scrubber, please refer to the document below. If interested, we are available to assist your facility with a trial to allow you to further realize the benefits provided by INVISTA DBA. Our technical experts can assist with planning the trial, analytical measurements and discussion of results. In addition, a custom INVISTA test 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.
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 Testing INVISTA Dibasic Acid (DBA) in Wet Scrubbers.pdf (187 kb)
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| Flue Gas Desulfurization Brochure |
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| For more detailed information about the use of INVISTA DBA in 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”. |
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