EVALUATING MATS OPTIONS WITH FIELD DEMONSTRATIONS

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1 EVALUATING MATS OPTIONS WITH FIELD DEMONSTRATIONS Robert L. Huston,* Sheila H. Glesmann and Joseph M. Wong ADA Carbon Solutions, LLC, 1460 West Canal Court Suite 100, Littleton, CO Noah D. Meeks Southern Company, 600 North 18th Street, Birmingham, AL ABSTRACT In planning for compliance with EPA s Mercury and Air Toxics Standard (MATS), there are many options and implications to consider. Comparison between technologies is best achieved through field testing. The multitude of testing programs and field data available today have led to improved strategic thinking and planning. Several key philosophies are synthesized in a few Guiding Principles that enable a clearer path to compliance planning and execution. As one of the Principles, getting a handle on balance-of-plant and multipollutant interactions is critical to success. One area is ash utilization, which recent improvements in activated carbons and lower injection rates have improved. Past testing has also shown that mercury control performance degrades with SO 3 present, through injection or native high sulfur coal. Tests using newly developed powdered activated carbons (Generation 2 and 3 PACs) have shown that performance is significantly improved over conventional PACs and that dry sorbent injection (DSI) for acid gas control impacts this. In certain applications, a marked effect is seen with interactions between DSI and ACI, which are both necessary for successful MATS compliance. These correlations are presented, and the implications for compliance planning discussed. INTRODUCTION EPA s Mercury and Air Toxics Standards (MATS) compliance dates are coming up, and coal-fired power plants affected by the rule are actively pursuing emissions solutions that fulfill realistic compliance strategies. With deadlines for compliance in 2015 and 2016 (for units that obtain a one-year delay), time is getting short for major procurement decisions, resulting in less time for testing and selection of options/alternatives. As the thought process is driven forward by strategic planning, the priority of full plant integration, including all existing processes, and fully considering impacts and interferences, has become the driver behind compliance planning decisions. Once the rule takes effect, mercury limits will have to be met on a 30-day rolling average at 1.2 lb/tbtu for most coals (4 lb/tbtu for low-rank lignite coal). Considerations in addition to mercury capture, such as multi-pollutant effects, co-benefits of control devices, economics of alternatives, impacts to other equipment and process modifications need to be quantified and measured. The goal is to anticipate and minimize adverse impacts, preserving the vital and primary purpose of the power generator and its major equipment, while not compromising the ability to comply and produce at desired levels. A holistic view of the power plant system is needed to effectively manage the many compliance activities that power plants face. Improved test data and availability, deeper understanding of the underlying science, and practical experience have driven better integration options. Synthesizing many of these learnings and gaining a better understanding of mercury control options are challenges that EGUs are facing. It helps to have a paradigm, or Guiding Principles to address these issues constructively. In this paper we describe a set of Guiding Principles that put some of these decisions in context and enable better planning. ACI Systems that are installed and operated to meet MATS timing will then be optimized over time to reduce sorbent consumption or switch to next-generation advanced PACs that provide improved reliability, removal and/or controllability to the specific emissions target. Since each power plant has some unique characteristics, where operational history will inform results, operators will drive customization and optimization once compliance becomes routine. A specific example of optimization based on operating experience was observed during testing at Southern Company s Plants Barry, McIntosh and Smith using DSI and ACI together. Results demonstrate the need for testing and for real-world operating experience to understand the interactions of different emissions controls and 1-Huston

2 the balance-of-plant impacts. Some of these learnings will not occur until after MATS is in place. But, test programs are extremely valuable in making informed decisions. EXPERIMENTAL APPROACH The approach in this paper is a synthesis of regulatory and compliance planning information, test program insights, laboratory and field tests and technical expertise into a set of Guiding Principles that provide a framework for MATS strategy development. Test data from several test campaigns out of over 65 full plant tests are used to support and exemplify certain key points. Powdered Activated Carbons are significantly improving for mercury capture applicability. Instead of the earlier approach of applying activated carbon designed for water treatment to flue gas treatment applications, now the PAC industry is developing Generation 2 and 3 PACs that improve performance specific to mercury capture in coal-fired flue gases. Niche applications are addressed with specialty products that work well in a range of challenging environments, but currently with little operational history. ADA Carbon Solutions approach in new product development is to fail safe, meaning to perform on a mercury capture basis at least as well as our baseline/generation 1 products as we introduce new products to customers niche applications. This new product development approach has been very effective in developing the collaborations needed to get demonstration products out to the field and show that they work in the real application with all its nuances. Products that preserve mercury capture effectiveness while addressing balance-of-plant impacts are our goal as an effective supplier. As we develop new tools to predict performance and prove the ability to fail safe, prototyping of new products and scaling them for field demonstration are rapidly proceeding. But power plants face a much more complex picture than PAC injection, as a very complex regulatory environment that includes all environmental media exists. 1 Critical concerns regarding reliability of supply, seasonal performance and supply factors, quality, predictability and flexibility to utilize newly developed, improved products while minimizing balance-of-plant effects still exist. Even for units that have very high native mercury capture, the mechanism of this capture should be examined to understand if it is sustainable over time, with fuel switching, with APC interactions and with future planned retrofits, or if a backup system may be needed. Many test programs have been conducted, and real-world compliance has been achieved in the past several years. Combining this wealth of information with the scientific approach that ADA Carbon Solutions embodies yields several principles that drive the thought process for mercury compliance planning. Laboratory testing that demonstrates foam stability has been conducted by modifying a standard procedure. 2 examining foam stability over a longer period of time, various sorbents can be compared and key concerns about timing of concrete utilization can be addressed. By RESULTS AND DISCUSSION The Guiding Principles 1. Scientific Approach Use science to understand your mercury capture and any other effects. For example: Contact, Conversion and Capture must occur to remove mercury from the system. Each of these mechanisms must occur to a high degree of efficiency. The mercury must come in contact with a collecting media to remove it from the power plant system, even though the mercury is in a very dilute concentration (ppb levels). The statistical probability of contact with the mercury is very low. This step of Contact is also essential for overall mercury capture to be effective. Elemental mercury has low reactivity and is not readily captured by PACs. But oxidized mercury has enhanced reactivity and can be captured. This change in state from elemental to oxidized mercury is Conversion. And finally, for long term removal of mercury from the environment, the diffusion and sequestration of mercury into the structure of the activated carbon must occur. This third mechanism is Capture. Ensuring that mercury is irreversibly captured is a key attribute that is often not accomplished. All 2-Huston

3 three mechanisms must occur in as little as half a second up to a few seconds to achieve rapid and effective mercury capture. With this framework in mind, any individual plant configuration can be evaluated for the potential and reliability of mercury capture. Coal composition, halogen additives, halogenated sorbents and SCR efficiency are a few of the variables that affect Conversion. Sorbent type, location and injection/distribution systems and/or scrubber design and chemistry can affect Contact. Capture and subsequent removal from the system can be the biggest challenge. Where do you want the mercury to end up? This is where a holistic view is key to success. Ensuring that Capture occurs effectively and securely is the third key to successful long-term operation. Changes to the system can affect mercury capture to improve or degrade it. But with the key scientific principles of Contact, Conversion, and Capture, an initial analysis can be done to understand the mercury capture mechanisms and assess their reliability. For example, in the event that an SCR that usually provides Conversion is in bypass mode or if the oxidation catalyst layer is spent or partially deactivated, an alternative is to utilize a halogenated PAC to achieve Conversion. In the event that any one of the three mechanisms fails due to process conditions, mercury capture will be compromised. But, these are issues that can be addressed and designed into the compliance plan once the mechanisms are well enough understood on a scientific basis. It is also critical that each of these three mechanisms occurs at the highest possible efficiency. For example, if the air pollution control (APC) train is 90% efficient in each of Contact, Conversion, and Capture, the overall mercury control is only 0.9*0.9*0.9 = 73%. This level of control is in many instances not sufficient for continuous compliance. 2. Single-phase approach simplifies or eliminates downstream interactions move it upstream Mercury material balances across the APC train are challenging to measure and close and speak towards the specificity and complexity of the air pollution equipment. Therefore, a reliable description of where the mercury resides in the system is not universal. We know that mercury enters with the solid coal, and when heated in the boiler, partitions predominately into the flue gas, with some mercury in the particulate phase, including the bottom ash. The bulk, however, is conveyed through the flue gas phase and carried by entrained solid fly ash to the precipitator (ESP) or baghouse. Assuming that the flue gas is kept above its dew point, then mercury control can be focused in a single point in the process. But if this does not happen, or does not happen securely, the mercury continues downstream. As the mercury is carried downstream towards the stack, it faces a greater multitude of factors that challenge its collection. For example, many power plants use a wet scrubber for acid gas control. Mercury from the flue gas upon entering the scrubber is cooled, contacts with the aqueous spray and solid slurry and is accumulated in the scrubber reservoir. The mercury partitions into three phases: the liquid (water) and solid (gypsum) phases and some of it remain with the gas phase (flue gas). The addition of lime, air and scrubber control additives further compounds the chemistry and phase distribution thus creating uncontrolled operating conditions that impede good mercury capture. In a case study presented in 2012, CPS Energy with URS reported that their wet scrubber had several limitations and potential adverse impacts when used for mercury control. Native control was inadequate to meet current and future standards. Enhancement of mercury control in the scrubber using calcium bromide was effective but carried the risk of increased blowdown from bromine buildup in the scrubber, and possibly re-emissions. Steady state operation was not achieved and a full evaluation of scrubber impacts would take a longer test program. Overall, activated carbon injection with a halogenated PAC was most cost-effective and kept the mercury control within the baghouse, avoiding scrubber impacts. 3 For more efficient and predictable mercury capture, we recommend focusing on maximizing the mercury capture as early in the APC train as feasible and ideally driving high control efficiency in the flue gas phase, namely capture from the flue gas directly to the solid phase, where it can be captured securely and removed from the system by an ESP or baghouse. 3-Huston

4 3. Active control rather than passive Power plant operators, whether at the plant or in management, are well-served by having an engineering control within their APC processes that they can dial up rapidly to obtain increased mercury control or back off on when overcontrolling. APCs, such as the SCR, once installed have a fixed performance for oxidizing mercury, but over time this mercury Conversion performance will degrade without a lever for the operator to adjust to compensate. Similarly, the wet scrubber is a very large and expensive control system with a large inventory of liquid slurry, chemical constituents and accumulated contaminants. Control parameters for mercury control are variable or inconsistent for different scrubber systems, and instantaneous control is for the most part unavailable. ADA Carbon Solutions newer Generation 2 and 3 PACs are ideally suited to fine-tuning mercury control in the region of interest near the compliance level. These PACs are designed to deliver high reactivity and diffusion to facilitate rapid Contact, Conversion and Capture. The steep capture curve of FastPAC Premium enables tight compliance management through responsive control a relatively small adjustment in PAC injection rate has a corresponding large change in mercury capture Retain and preserve original purpose of equipment Power generation is the primary purpose and should not be threatened by an unreliable solution for compliance. Back-end scrubbers are large systems designed for purpose, to control acid gases. Adjusting these systems to address mercury capture can have collateral effects that impede the original purpose of the design, resulting in a preference for removal of mercury upstream of the wet scrubber, as described above. Backend equipment can also be impacted adversely by free bromine, a subject of an ongoing EPRI study that has also identified a tendency for selenium to move from the fly ash to the scrubber when bromide addition is used. 5 Section 45 has led to many plants using bromide additives to the coal for mercury capture. There is a wide range of effectiveness of this approach. The integration of the full plant for co-capture of mercury has tremendous value in efficiency of operation, but each facility must evaluate its options in order to determine the impacts and decide on its most economic approach. 5. Minimize balance-of-plant and other emission interactions Potential adverse balance-of-plant (BOP) impacts of a plant s MATS compliance strategy that should be considered and evaluated include corrosion of air preheaters, scrubbers or other downstream equipment from injection of halogens, pressure drop or equipment plugging issues, opacity, and ash utilization. Emission interactions for scrubbers include impacts to the overall acid gas control performance, concentrations of bromide, mercury and selenium, and buildup in effluent and/or gypsum products. Where DSI is used for a variety of reasons, compatibility between DSI and ACI is a consideration for which mechanisms are not yet fully understood. It is challenging to obtain a good mercury mass balance in general and even tougher at sites with complex APC equipment, but if the objective is to obtain stable long-term control it is important to understand where the mercury and any additives used to obtain compliance are going. Ash Utilization An added benefit to lower PAC consumption with newer products such as FastPAC Premium is that PAC use is optimized and balance of plant issues are reduced. For example, there has been much hype concerning concrete compatible PACs. A recent study presented by Lafarge cites that all sorbents have an adverse impact on Air Entrainment Agents (AEA) usage and stability and fly ash consistency. 6 The true remedy is to use Generation 2 and 3 PACs that are highly efficient for mercury capture, thus minimizing PAC injection requirements and having less impact on fly ash variability. Figure 1 shows the impact of PAC on the AEA requirements over time for a concrete mix with 20% fly ash replacement and at an equivalent to approximately 3 lb/mmacf PAC injection rate. Criteria for good concrete production include low initial AEA dosage and stable AEA requirement over time, which can be represented by 4-Huston

5 degree of Foam Stability. Foam Stability can be quantified by the concrete mix s AEA requirement to maintain targeted foam content over time. Competitive Generation 1 carbons represented in the top curve of the chart typically show high initial AEA dosage compared to the baseline fly ash without PAC in the bottom curve. Additionally, the AEA requirement continues to increase over time, requiring about a 50% increase in AEA dosing (17 to 25 drops) through 120 minutes after the initial dosage. This Foam Stability behavior would indicate that the concrete mix would be out of specification, as AEA addition after the initial dosage is not feasible in practice. Our Generation 2 FastPAC Premium offers a 50% lower initial AEA dosage compared to Generation 1 PACs and attains a stable AEA requirement after minutes. After this initial time period, the AEA requirement is stable through 120 minutes. Drops of Air Entrainment Agent (50µL=1drop) Time (Minutes) Competitor 1 ADA FastPAC Premium Baseline Figure 1. Air entrainment agent drops required for stable foam under baseline and two sorbent blend conditions. Figure 2 shows that at lower equivalent PAC injection rates of 1 or 2 lb/mmacf, the initial AEA dosage is significantly lowered and Foam Stability is more favorably affected. ADA Carbon Solutions Generation 3 FastPAC Premium can achieve low injection rates in some applications that bring the levels down to this range (or even lower). This is significant because the ratio to baseline is another key parameter for ash marketers. Thus, PAC features of low injection rates for mercury capture, low initial AEA dosage and stable AEA requirement over time contribute greatly to beneficial fly ash use in ACI systems. 5-Huston

6 Drops of AEA (50µL=1drop) FastPAC Premium 3lbs/MMacf FastPAC Premium 2lbs/MMacf FastPAC Premium 1lbs/MMacf Fly Ash Only Time (mins) Figure 2. Reduction in air entraining agent required for foam stability with reduction in PAC. Figure 3 depicts test results from a PRB-fired unit with ACI upstream of a baghouse. This chart shows that Generation 1 products can be efficient in certain applications. The control system was effective at maintaining >80% capture, and improved injection levels could likely be obtained over time, since there is no degradation in control at the lower end. FastPAC Premium improved on the injection rate by about 25% and enabled the ash to be sold for concrete use. For legibility, this data is not shown on the chart. Mercury Capture across Baghouse, % PowerPAC Premium 550 Megawatt Unit PRB Coal o APH, ACI, Baghouse o CEMS feedback control ACI Injection lb/mmacf Figure 3. PowerPAC Premium test results using a CEMS feedback loop to an ACI system on a 550 MW PRB coal-fired plant with a baghouse. 6-Huston

7 Impacts of DSI and PAC While DSI can be used in small amounts to enhance mercury sorption by protecting the carbon from SO 3, recent industry experience has shown that excessive DSI may be a detriment to mercury sorption. Unlike ACI, which is exclusively used for mercury control in power plant applications, there are a number of uses for DSI besides enhanced mercury control. However, these applications of DSI may cause negative BOP and cross-media impacts. Appropriate minimization and management of DSI are keys to maintaining both effective mercury control as well as plant operations. Dry sorbent injection includes the use of any alkaline or alkaline earth material injected for the neutralization of acid in the flue gas. Although denoted sorbents, these are actually reactants which are selected due to their chemical properties of reaction, not a high surface area or porosity for sorption. The most commonly used dry sorbents are hydrated lime (calcium hydroxide), baking soda (sodium bicarbonate), and trona (a mineral form of baking soda and soda ash). These chemical bases react with acid gases or acid mists to form neutral compounds. DSI is often used to neutralize SO 3, a trace compound that has extensive negative impacts on the power plant operation. SO 3 interferes with mercury removal by conventional PACs, creates a blue plume at the stack, reacts with ammonia slip from the SCR to form ammonium bisulfate (causing plugging) on the air pre-heater and degrades fabric filters (particularly if the baghouse is operating below the SO 3 dewpoint). With the MATS rule, DSI may be used on units without wet flue gas desulfurization (WFGD) to neutralize HCl for compliance. For plants that have SO 2 limits but no WFGD, large amounts of DSI are sometimes used. Finally, DSI may be used to control acidic selenium in the flue gas, before it requires treatment in the WFGD wastewater, or before the selenium can interfere with amine absorption in a carbon capture process. Recent data from Southern Company plants demonstrate the enhanced mercury removal from DSI, as it neutralizes SO 3. For an eastern bituminous fuel emitting about 1,000 ppm SO 2, the SO 3 level is estimated to be about 10 ppm, which is high enough to severely impact mercury removal. Injecting PAC at 100 lb/hr without DSI provided less than 10% mercury control, but injecting it with 1,000 lb/hr DSI provided about 90% control. 7 All the chloride had not been neutralized; at the stack the HCl concentration was still greater than lb/mbtu. However, recent data from Southern Company plants demonstrate the potential negative effect of DSI on mercury removal. These plants were test burning Powder River Basin subbituminous fuel or Colombian bituminous fuel, and the figures show mercury removal data with various ACI rates. For Colombian bituminous fuel (Figure 4), the mercury emissions with no DSI and 250 lb/hr ACI, were about 0.5 lbhg/tbtu. The emissions doubled with the same ACI and ~4,000 lb/hr hydrated lime injection. With 4,000 lb/hr trona injection, the mercury emissions had quadrupled. (Though this injection was not needed to achieve MATS HCl limit, the DSI was injected as part of a separate effort on SO 2 emissions at this particular plant.) Also seen on Figure 4, when the ACI rate was increased to 350 lb/hr, MATS levels were met and hydrated lime DSI had a slight positive effect on mercury control. With PRB fuel, the same effect was seen with 1,000 lb/hr DSI. With 100 lb/hr ACI, the mercury emissions were well below the MATS limit (Figure 5), but with addition of hydrated lime the emissions doubled, and tripled with the addition of trona. The effect is most clearly seen in a day by day breakdown of the emissions Figure 6 shows the decreasing mercury emissions when the ACI is turned on, then the subsequent increase in mercury emissions when DSI is started simultaneous with the ACI. A different plant (Figure 7) did not have the same effect when only injecting 500 lb/hr DSI, suggesting that the effect is related to the amount of DSI. Taken together, these observations are consistent with wider industry experience in recent months and support a few general observations. While the mechanisms of mercury emissions increase are not fully known, the effect arises from both lime and trona. This suggests a potential inhibition of the conversion step in mercury removal, as the DSI neutralizes chlorides needed in mercury oxidation (conversion) for efficient removal. However, the effect is consistently greater with trona than with hydrated lime, and it has been proposed that the trona catalyzes the formation of NO 2, which is hypothesized to negatively impact the ACI efficiency in much the same way as SO 3. The effect is correlated with the amount of DSI and the context of its application. The data 7-Huston

8 also suggest that the negative impact on mercury control efficiency can be overcome by increasing PAC injection rates. An alternative is to examine SO 3 -tolerant PACs, enabling minimization of DSI while retaining mercury capture. 7 Besides impacting mercury control efficiency, DSI may have cross-media impacts. These are dependent upon plant configuration as well as DSI type, and can be generally grouped into two categories if collected with the fly ash. The two broad categories are solids handling effects and ash sluice water effects, and the effects in both categories are strongly influenced by the physicochemical properties of the calcium and sodium. Calcium compounds are less water-soluble than sodium compounds; therefore, Ca-rich ash is more suited as a cement additive. Also Ca-rich salts leach less and are more physically stable in landfill applications. The more covalent nature of calcium salts renders it more resistive; therefore, calcium generally has more negative effects on electrostatic precipitation efficiency than sodium. In ash sluice water, the lower solubility of calcium causes less ph increase than sodium, but the neutralization of Ca-rich sluice water is more difficult than that of Na-rich sluice water. Depending upon the reasons for DSI usage, there may be alternatives. Whether these are prudent depends on the specific plant context and cross-media impacts that are actually present. If the usage of DSI is for enhanced mercury control through SO 3 neutralization, a potential alternative is the use of SO 3 -tolerant mercury sorbent or alternative mercury removal technology. If the purpose is SO 3 neutralization other than for enhanced mercury control, HCl neutralization or SO 2 neutralization, real-time monitoring of those pollutants could help minimize cost of negative impacts associated with excess DSI. More expensive alternatives in these scenarios would be fuel switching or the installation of wet FGD. For potential future applications of DSI in acidic selenium neutralization, alternatives could include development of real-time Se monitors to minimize DSI, implementation of Se sorbents, fuel switching, wet ESP technology or utilization of wet scrubbers for Sespecific control. Figure 4. Mercury emissions at 250 lb/h ACI increase with addition of 4,000 lb/h DSI on Colombian fuel. 8-Huston

9 Figure 5. Mercury emissions increase at 100 lb/h ACI with 1,000 lb/h DSI on PRB fuel. Figure 6. Hourly mercury emission rates show that ACI reduces the emission rate, which is increased with simultaneous ACI/DSI. 9-Huston

10 Figure 7. Mercury emissions are not consistently affected by 500 lb/h DSI on PRB fuel. CONCLUSIONS There is a need to synthesize a great deal of scientific understanding, actual test data, integration of various emissions controls and balance-of-plant issues in order to form a coherent, effective and long-lasting MATS compliance strategy for a given facility. This paper outlines a few Guiding Principles to assist with developing a specific plan and if needed, contingency plans for a given site. Contingency planning is needed in the event that inadequate understanding of the process or real test data can be achieved or if fuel or air pollution control switches are implemented. BOP issues, including ash utilization and interactions between DSI and ACI, are important considerations in detailed planning. A good plan will outline a clear roadmap to assess existing APC train effectiveness and establish the best combination of process options. In summary, we recommend the following: Scientific approach. Utilize the fundamentals to understand what is happening in your system and when interpreting test data. Contact of the mercury with a collection medium, Conversion of the mercury to an oxidized form, and Capture of the mercury for removal from the power plant each need to take place. Many phenomena in mercury control can be explained by understanding and applying these mechanisms. The Generation 2 and 3 sorbents FastPAC Premium and FastPAC Premium-80 are designed to achieve these three mechanisms in a highly cost-effective manner. Move it upstream to a single control point. Removal of mercury in a specific, controlled manner upstream of a particulate collector contains the conversion, contact and capture in a well-defined area of the power plant that can be well controlled. 10-Huston

11 Active control. The ability to turn a dial and obtain improved mercury control is a valuable tool for operators. They also want to be able to dial it down as improved technology makes PAC more efficient or co-control is more effective under certain operating conditions. The more flexibility the plant plans to have in terms of fuel supply, SCR in or out of service (or degradation) and load variability, the more essential it is to have an active control knob. Retain the original purpose of APC systems. First and foremost, the compliance method must be very reliable to preserve the power plant s primary purpose of power generation. Scrubbers and other large backend systems are built-for-purpose as criteria pollutant controls. Trace species such as mercury, bromine and selenium can buildup concentration in scrubbers when bromide addition is relied upon in combination with a wet scrubber, and mercury control may not be reliable over time using a passive control device. Utilizing ACI upstream of a particulate collector minimizes downstream impacts and retains the primary purpose of APC systems. Protection of downstream equipment for its primary use may also be needed for selenium control for future carbon capture systems, as described above under Impacts of DSI and PAC. Minimize Balance-of-Plant impacts. Ash utilization options are improved using newer sorbents with their lower injection rates and characteristics specific to improved foam stability. DSI is needed for a variety of reasons, but it can have cross-media impacts on ash utilization, particulate collection, and ash sluice water. Minimizing DSI helps to reduce these effects, which can be done by utilizing SO 3 -tolerant PAC such as FastPAC Premium- 80. In field testing of DSI in combination with ACI, trends indicated that DSI was helpful to ACI mercury capture up to a certain level. This level was seen to retain some HCl at the stack, indicating that the flue gas still had ability to oxidize or convert the mercury. Once DSI was increased beyond this level, mercury capture was impeded in this limited testing. This was not a full optimization of ACI and DSI interactions, but rather underscores the importance of obtaining adequate test data and applying the scientific fundamentals to its interpretation. In this case, there is an indication of inhibition of the conversion mechanism that bears consideration when interpreting future test data. REFERENCES 1 Kinsman, J., Electric Generation Environmental Issues, A2.1 at EUEC Conference, Jan W.R. Grace Technical Bulletin TB-0202, The Foam Index Test: A Rapid Indicator of Relative AEA Demand, Blythe, G., J. Bissell and L. Labatt, Optimization of Mercury Control on a New 800-MW PRB- Fired Power Plant, Paper No. 84, 2012 MEGA Symposium. 4 Huston, R., Activated Carbon Performance in Emission Systems, Track C at EUEC Conference, Feb Dombrowski, K., K. Arambasick, R. Chang, C. Tyree, Balance of Plant Effects of Bromine Addition for Mercury Control, Paper No. 93, 2012 MEGA Symposium. 6 Kline, J. and A. Delagrave, Sorbent Testing in the Lab and Field, C.7.6 at EUEC Conference, Jan Looney, B., Meeks, N., Cecil, J., Huston, R., Wong, J. and Johnson, E. Advanced Activated Carbons for Efficient Mercury Removal, C.1.4 at EUEC Conference, Jan Huston