Mercury Control in North America Using Powdered Activated Carbon (PAC)

Transcription

1 Mercury Control in North America Using Powdered Activated Carbon (PAC) Mercury Emissions from Coal (MEC 12) 2 March 2017 Sheila Glesmann ADA Carbon Solutions, LLC 1

2 Outline U.S. Compliance Trends Continued Optimization State of ADA Carbon Solutions PAC advancements Synergies of controls together Anticipating future needs for change Coal flexibility, load cycling Water and ash management - intersections with air pollution control choices Conducting useful testing and demonstrations 2

3 ADA Carbon Solutions, LLC ADA Carbon Solutions is committed to flue gas mercury control. We manufacture powdered activated carbons and continuously drive improvement through science using our in-house R & D and collaboration Headquartered in Littleton CO and operating three facilities in Louisiana Since 2008 have built significant market share in the North American mercury control market Personnel experience in coal-fired mercury measurement and control goes back to 1990 s technology development for EPRI, DOE, utilities The decades of power plant mercury control experience is invaluable for evaluating and applying technology efficiently 3

4 Mercury Control Applications under MATS EPA s AMPD (Air Markets Program Database) provides data on compliance technologies On Sep 30 (downloaded Feb 2017) 324 coal-fired units reported an hourly mercury emission value midday. About 220 of these have a mercury-specific technology listed. Activated Carbon Injection (ACI) is the BACT and MACT technology Over 70 GW documented by DOE s Energy Information Agency from 2014-April 2016; understates magnitude Many coal-fired plants were already using ACI under state rules, permits, and consent decrees ICAC documented >135 GW (over 300 units) as of late 2014 EPA s AMPD shows over 200 units reporting ACI as part of strategy; database is incomplete 4

5 AMPD-Reported Mercury Control under MATS Additives In EPA s AMPD there is no distinction between coal additives (e.g. halogens on coal) and/or scrubber additives (e.g. sulfides or PAC) All wet scrubber additives require oxidation of mercury upstream of scrubber, this can be accomplished through native halogens in coal or halide additives, and/or through SCR About 80 units list additives as part of strategy Other technologies include catalyst (10 units), non-pac sorbents (2 units), sodium-based (4 units), regenerative activated carbon (1 unit); many list multiple technologies 5

6 Safe PAC Material Handling The Good News PAC has been safely handled at industrial sites for decades in water treatment and in the past 20 years for flue gas injection. To many utilities however, it is a new material. It is distinct from coal because our manufacturing process drives off volatiles and moisture, making it less susceptible to fire and explosion risk than pulverized coal. With knowledge of the proper handling it can continue to be a safe part of the industrial work environment. Some of the startup guidelines are connected to material handling safety. Education on the Safety Data Sheet (SDS) of the material, Personnel Protective Equipment (PPE) required, housekeeping/cleanup, and measurements available is recommended. For more details on safe PAC handling, refer to our handouts, product information and technical experts. Also ICAC White Paper is available on Safe Sorbent Handling 6

7 Relative Performance, all units # 7

8 Relative Performance of Lignite Units # 8

9 Optimization Over Time We have come a long way since early 2000 s PAC injection rates of 5-20 lb/mmacf and today, rates have dropped dramatically Plants have found ways to reduce sorbent use or do intermittent injection through improved distribution and Cobenefits Suppliers have advanced the technology to reduce sorbent consumption and address more-challenging applications: SO 3 -tolerant PACs and/or DSI for SO 3 management Higher temperature compatible PACs Sodium reagent interferences addressed Reduction in PAC usage as shown in case studies 9

10 Benefits of Optimization PAC is not the only cost Load cycling operation in a competitive power price environment has driven a laser focus on costs Lowest cost of compliance is key to success Compliance has to consider air, water, solids utilization/storage Lower PAC injection rates through improved products and finetuning process controls/feedback have led to Continued utilization of ash; improved foam stability; good strength properties Less impact from halogens / oxidation Learning curve on ability to manage the chemistry Reinforcement of key principle of removing mercury all at once with minimal balance-of-plant effect 10

11 PAC Innovations to Adapt to the Evolving Performance Landscape Traditional PAC Products Adapted for Mercury Removal Gen 1 Adaptation Power PAC TM Power PAC Premium TM Step-change Improvement in Hg Removal Efficiency Gen 2 Innovation Power PAC Premium Plus TM FastPAC TM Platform Resolving Specialized Emission Requirements Gen 3 Collaborative Specialization Concrete Compatible Acid/SO 3 Tolerant Trona Compatible High-Temperature Baghouse Optimized WFGD Optimized GEN 1 PACs developed in the mid-2000s are no longer the industry performance standard... it s new Gen 4 and Gen 5 carbons Optimization & Holistic Solutions Gen 4 & 5+ Balance of Plant & Multi-contaminant Specialization Corrosion Coal Combustion Residual (solids) & Effluent Limitations Guidelines (liquid)impacts Fate of contaminants (Br, Hg, Se, As, etc.) By-product sales 11

12 Emission Rate (lb/tbtu) Active Engineering Controls with Generation 2 PACs Steep, Rapid Capture Low Hg Residual & Secure Capture > 200 MW EGU PRB coal fired Emission Configuration: Econ-ACI-APH-ESP-Stack Gen 1 PowerPAC Premium Hg CEMS 1.0 GEN 2 FastPAC TM Premium -60% Emission Standard 1.2 lb/tbtu Lbs Activated Carbon / MMacf Gen 2 PACs can reduce carbon usage by 50% and Improved Hg Removal to >95% 12

13 Developmental Work Laboratory Results Our lab Dynamic Mercury Index (DMI) test provides rapid PAC Hg removal performance comparisons. Our patent-pending Gen 4 & 5 FastPAC series PACs have significantly enhanced Hg removal performance compared to standard Gen 1 PACs like PowerPAC Premium. # 13

14 Hg Emissions Full-Scale Testing of Advanced Gen 4 FastPAC Platinum PRB: Econ-SCR-DSI-APH-ACI-ESP-Stack Gen 4 FastPAC Platinum Target Emission Rate ~40% reduction in PAC Usage Gen 2 FastPAC Premium ACI Rate Our Gen 4 FastPAC Platinum reduced PAC usage by 38% compared to our Gen 2 FastPAC Premium in a sodium DSI system. # 14

15 SO 3 Tolerant PACs Provide a Dramatic Improvement in PAC Performance Hg Total µg/dscm ppm SO Native Removal FastPAC Platinum Plus With SO 3 Tolerance FastPAC Platinum Plus Without SO 3 Tolerance Operating Target ~40% Reduction in ACI Rate PAC Rate, lb/mmacf Our Gen 5 FastPAC Platinum Plus with SO 3 tolerant features reduced PAC injection rate by 43% over over a similar PAC without SO 3 tolerant features. # 15

16 Stable Capture without Re-emission of Mercury Mercury re-emission from wet scrubbers is well documented Southern Company - EPRI/URS paper #57 from 2014 MEGA describes oxidized Hg being reduced to elemental in the wet scrubber and re-emitting Stack Hg exceeds inlet Hg under changing process conditions Good example of Contact-Conversion-Capture not succeeding The same concept applies to other temporary capture techniques Fly ash LOI capture of Hg can result in re-emission or leaching; oxidation without stable capture does not achieve control goals Activated carbon injection can be used in flue gas or slurried into a scrubber Scrubber additives include sulfides that precipitate mercury Removal from the system is also key; these solids need to be separable Good results have been reported with either PAC or sulfides in scrubbers catch is that injecting halogens throughout the boiler and process has collateral effects 16

17 Field Test at Salt River Project Navajo Generating Station SRP Navajo Unit 3 tested over a 4.5 month period Several technologies had been evaluated These results are using ADA-CS PowerPAC WS Three 750 MW units Western bituminous coal Low sulfur coal Two wet FGD absorbers/unit Hg µg/g CaBr 2 injection Activated carbon injection in wet FGD in slurry form using STEAG technology Technology was selected 17

18 1.2 lb Hg/TBTU compliance level was achieved No CaBr 2 & No PAC Met 30-Day Rolling Average for MATS Compliance with Calcium Bromide Treatment on Coal and PowerPAC WS in Wet FGD (A&WMA MEGA Symposium 2014 Paper #90) 18

19 Key PAC Benefits for Wet FGD (LSFO) Applications No bulk chemistry/orp impacts: For low ORP scrubbers, PAC does not impact ORP as do sulfide additives, and this removes the risk of overshooting and impacting gypsum quality For scrubbers that do not monitor ORP, ORP and ph do not impact PAC s effectiveness Gypsum Preservation: In work by Southern Company and URS/AECOM, successful separation of PAC from gypsum was achieved by tuning hydrocyclones. Marketing the gypsum for wallboard or agricultural use have proven effective Low dosage for effective control: Southern Company tests showed that PowerPAC shifted the liquid phase Hg to the solid phase (95%) at ppm PAC addition 19

20 Mercury Compliance While Avoiding Halogen/Oxidation-Driven Corrosion BOP Issues We have taken a fundamental scientific approach to examine each of pores, surfaces and particles to optimize mercury capture based on specific flue gas requirements Use of laboratory tools and full-scale test feedback loop to drive Contact, Conversion and Capture while tuning mercury removal to minimize reagent consumption and BOP impacts Some common takeaways: o o o o o Use a low-volatility halogen salt (e.g. Sodium Bromide NaBr) Use a halogen concentration that assures effective and efficient Hg oxidation but is not in excess to cause BOP issues Design PACs so that the halogen is at the surface of the PAC particle to maximize accessibility to the gas phase Hg and to insure efficient halogen utilization and apply in a way that it is also less water extractable Use advanced Gen 4 and 5 PACs that require less consumption to reduce overall halogen levels in your emission system Evaluate next-generation non- or low-halogen PAC technologies 20

21 Intersections with Water and Solids Mercury can be partitioned in the gas, liquid, or solid phase and subsequently concentrated and sequestered by control technologies, but not destroyed; similar to Se and As - all key water and waste (RCRA) metals Philosophy of active control (a control knob ) Mechanistic approach to ensure completion of Contact Conversion Capture CaBr 2 injection on coal has been shown to increase the scrubber liquor Se content, increasing water treatment system loading Secure capture needed to ensure ash and effluent streams are not adversely affected Reduced Hg and potentially Se loading to scrubber is beneficial for future water discharge technologies get them out as early as possible! Ash and other byproducts have value and utilization is increasing 21

22 Criticality of Testing Programs How do the options impact your plant? Establish performance ranges for design input (define variables: coal type or quality, loads, evaluating test methods, etc) Get the measurements right cross check methods Planning so the right things are measured - BOP Duration of test or demonstration is key to ability to extrapolate Good white paper on testing published by the Institute of Clean Air Companies (ICAC) in 2013: Conducting a Successful Mercury Control Demonstration Test at a Coal-Fired Power Boiler at 22

23 Resistivity Guidelines Provided by Robert Mastropietro of Nol-Tec Lodge Cottrell 23

24 Provided by Robert Mastropietro of Nol-Tec Lodge Cottrell 24

25 Native Control is the First Step Example of native control: SCR, ESP and wet scrubber Pros: No reagent use except SCR ammonia or urea SCR provides oxidation Wet scrubber captures oxidized mercury 25

26 Native Control has Limitations Example of native control:scr, ESP and wet scrubber Cons: SCR oxidation/conversion of Hg may be inconsistent as catalyst ages; no control knob to turn/passive control Insufficient oxidation results in pass-through of elemental Hg Wet scrubber is a large sink for mercury but may not be stable as process conditions vary : re-emission risk Cycling up scrubber concentrations to reduce effluent flow is limited by halogen content Ash and unburned carbon have a loose hold on mercury captured in ESP; is it stable? 26

27 Management and Technology Synergies Example of native control: SCR, ESP and wet scrubber Management: May be able to manage ORP and ph of scrubber liquor to minimize re-emissions (challenging) Understanding the fate of emissions in each individual system and trace metals fate requires informed testing Water effluent management: stability of stream flow and concentration into effluent treatment/bio system is crucial 27

28 Guiding Principles Remember scientific principles for Conversion Contact Capture and obtain accurate mass balances where achievable to confirm fate of trace species Assess the stability of those species and the process streams Engage active rather than passive controls Revisit compliance strategies as appropriate when new requirements or operating conditions develop (water discharge control, new coal, etc.) Remove the Hg upstream as far as possible to minimize entropy and utilize scrubber for primary purpose: acid gas control Always evaluate Balance-of-Plant impacts such as ash utilization, corrosion, scrubber chemistry, etc. Testing is critical to demonstrate results and effects 28

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30 Integrating the APC System to Maximize Native and Co-benefit Hg Capture Technology solutions need to be cost effective for Hg control and favorable to balance-of-plant considerations. Coal Pretreatment Combustion Oxidation Dry Sorbent Injection Sorbent Injection Wet Scrubber Additives Post Scrubber Treatments Integrate technology options and actively manage mercury control. Maximize native capture of mercury. 30

31 Mercury Inventory and Projected Impact of MATS 31

32 References/Resources Power Engineering article Nov 2016 MATS and Beyond: The Role of Technology Choices in Present and Future MATS Compliance Available in pdf format for download at Power Magazine articles March 2014 The Role of Activated Carbon in a Comprehensive MATS Strategy April 2015 The State of U.S. Mercury Control in Response to MATS Conducting a Successful Mercury Control Demonstration Test at a Coal-Fired Power Boiler Process Implementation Guidance for Powdered Sorbents at Electric Generating Units MEGA Symposium papers 2014 and 2016 available upon request Aug 2014 Field Demonstration of Advanced Activated Carbon for Mercury Control in Wet FGD Aug 2016 MATS Problem Solving: Advancing SO 3 -Tolerant Activated Carbons Through Pilot Demonstration World of Coal Ash (WOCA) paper April 2015 Evaluating Impacts of Ash Quality of Powdered Activated Carbon for Mercury Control DOE Energy Information Agency snapshot of MATS retrofits from 2014-April 2016: # 32

33 Thank You and Questions? Sheila Glesmann SVP Environmental and External Affairs Joe Wong Chief Technology Officer 33